Brief Report of GENCO Thermal Power Station 3 Muzaffargarrh (Internship Report MNSUET Multan)

Contents Chapter 1 Power Resources and Power Plants .......................... ....................................... .......................... .................... ....... 1-16

1.

Introduction .......................... ........................................ ........................... ........................... ........................... .......................... ........................ ........... 1-16 1.1. Objectives ......................... ....................................... ........................... .......................... ........................... ........................... .......................... ............. 1-16

2.

Sources of Energy – Fuels .......................... ....................................... .......................... ........................... ........................... ............... .. 1-16 1.2. Types of Fuels ......................... ...................................... ........................... ........................... .......................... .......................... .................... ....... 1-17 1.3. Fossil fuels ............................... ............................................ ........................... ........................... .......................... ........................... .................... ...... 1-17 1.4. Coal .......................... ........................................ ........................... ........................... ........................... .......................... .......................... ...................... ......... 1-17 1.5. Hydroelectric ........................... ........................................ ........................... ........................... .......................... .......................... .................... ....... 1-18 1.6. Types of Hydroelectric Power Plants ................. .............................. .......................... .......................... .................... ....... 1-18 1.7. Micro-Scale .......................... ........................................ ........................... ........................... ........................... .......................... ...................... ......... 1-18 1.8. Small-Scale ......................... ....................................... ........................... ........................... ........................... .......................... ........................ ........... 1-18 1.9. Run-of-the-River .......................... ....................................... .......................... .......................... ........................... ........................... ............... .. 1-19 1.10. Problems with Hydroelectric Power ......................... ....................................... ........................... ........................ ........... 1-19 1.11. Advantages and Disadvantages .......................... ....................................... .......................... ........................... .................. .... 1-19 1.12. Solar ......................... ....................................... ........................... ........................... ........................... .......................... ........................... .................... ...... 1-20 1.13. Problems with Solar Power .............................. ........................................... .......................... ........................... .................... ...... 1-20 1.14. Advantages and Disadvantages ............................ ......................................... ........................... ........................... ............... .. 1-21 1.15. Wind ........................... ........................................ ........................... ........................... .......................... .......................... ........................... .................. .... 1-21 1.16. Problems ......................... ....................................... ........................... .......................... ........................... ........................... .......................... ............. 1-21 1.17. Advantages and Disadvantages ............................ ......................................... ........................... ........................... ............... .. 1-21 1.18. Geothermal ......................... ....................................... ........................... ........................... ........................... .......................... ...................... ......... 1-22 1.19. Advantages and Disadvantages ............................ ......................................... ........................... ........................... ............... .. 1-22 1.20. Ocean Energy .......................... ........................................ ........................... .......................... .......................... ........................... .................. .... 1-23 1.21. Tidal Energy .......................... ....................................... ........................... ........................... .......................... .......................... .................... ....... 1-23 1.22. Wave Energy ......................... ...................................... ........................... ........................... .......................... .......................... .................... ....... 1-23 1.23. Nuclear Energy ................................... ................................................. ........................... .......................... .......................... .................... ....... 1-23 1.24. Nuclear Fission ...................................... ................................................... .......................... .......................... ........................... .................. .... 1-24 1.25. Nuclear Fusion ....................... .................................... ........................... ........................... .......................... .......................... .................... ....... 1-24 1.26. Classification of Power Plants .......................... ....................................... .......................... ........................... .................... ...... 1-24 1.27. By Fuel ......................... ....................................... ........................... .......................... .......................... ........................... ........................... ............... .. 1-25 1.28. By Prime Mover ...................................... ................................................... .......................... ........................... ........................... ............... .. 1-25 1.29. Steam Turbine Power Station .................. ............................... .......................... ........................... ........................... ............... .. 1-25 1.30. Gas Turbine Power Station .......................... ........................................ ........................... ........................... ........................ .......... 1-26

1.31. Pollution................................. Pollution.............................................. ........................... ........................... .......................... ........................... .................... ...... 1-27 1.32. Global Warming ...................................... ................................................... .......................... ........................... ........................... ............... .. 1-27 1.33. The Advent of Fossil Fuels.......................... ........................................ ........................... ........................... ........................ .......... 1-27 1.34. How Do Fossil Fuels and Biomass Pollute? Pollu te? ................................. .............................................. ................. .... 1-27 1.35. Other Polluting Poll uting Byproducts of Fossil Fuel and Biomass Bio mass Burning ............... ................. .. 1-28 1.36. The Spectrum of Pollution ......................... ...................................... ........................... ........................... .......................... ............. 1-28 Chapter 2 GENCO Thermal Power Station 3 ..................... ................................... ........................... ........................ ........... 2-29

2.1. Thermal Power Station ............................ ......................................... .......................... .......................... ........................... .................. .... 2-29 2.2. Thermal Power Station Muzaffargarh ........................... ........................................ .......................... ...................... ......... 2-29 2.3. Phase - 1 (Units 1, 2 & 3) .......................... ....................................... .......................... ........................... ........................... ............... .. 2-30 2.4. Main Building .......................... ....................................... ........................... ........................... .......................... .......................... .................... ....... 2-30 2.5. Combined Auxiliary Building .............................. ........................................... .......................... ........................... .................. .... 2-30 2.6. Fuel & Oil Facilities ................................ ............................................. .......................... .......................... ........................... .................. .... 2-31 2.7. Hydraulic Structures ................................ ............................................. .......................... .......................... ........................... .................. .... 2-31 2.8. Startup Boiler .................... .................................. ........................... .......................... ........................... ........................... .......................... ............. 2-31 2.9. Electrical Section ............................ ......................................... .......................... ........................... ........................... .......................... ............. 2-31 2.10. Phase-II (Units 5 & 6) .................................... ................................................. .......................... .......................... ...................... ......... 2-31 2.11. Overview .......................... ........................................ ........................... ........................... ........................... .......................... ........................ ........... 2-31 2.12. Boiler .......................... ....................................... ........................... ........................... .......................... .......................... ........................... .................. .... 2-32 2.13. Water Tube Type .......................... ....................................... .......................... ........................... ........................... .......................... ............. 2-32 2.14. Parameter of Boiler......................... ...................................... ........................... ........................... .......................... ........................ ........... 2-32 2.15. Main Parts of Boiler ......................... ....................................... ........................... .......................... .......................... ...................... ......... 2-35 2.16. Forced Draft Fan........................... ........................................ .......................... ........................... ........................... .......................... ............. 2-35 2.17. Induced Draft Fan (IDF) .......................... ....................................... .......................... ........................... ........................... ............... .. 2-36 2.18. Gas Recirculation Fan (GRCF) .......................... ....................................... .......................... ........................... .................. .... 2-37 2.19. Cooling Towers: ........................... ........................................ .......................... ........................... ........................... .......................... ............. 2-37 2.20. Cooling Water Pump ................................. .............................................. ........................... ........................... .......................... ............. 2-38 2.21. Condensate Water Pump ......................... ...................................... .......................... ........................... ........................... ............... .. 2-38 2.22. Air Preheater ...................... ................................... .......................... .......................... ........................... ........................... ........................ ........... 2-39 2.23. Economizers .......................... ....................................... ........................... ........................... .......................... .......................... .................... ....... 2-39 2.24. Boiler Protection ......................... ...................................... .......................... .......................... ........................... ........................... ............... .. 2-40 2.25. Thermal Power Cycle ............................ ......................................... .......................... .......................... ........................... .................. .... 2-41 Chapter 3 Steam Turbines ............... ............................ .......................... .......................... ........................... ........................... ........................ ........... 3-42

3.

Introduction .......................... ........................................ ........................... ........................... ........................... .......................... ........................ ........... 3-42 3.1. Rating & Design Data .......................... ........................................ ........................... .......................... .......................... .................... ....... 3-42

3.2. Description of Steam Cycle ......................... ...................................... ........................... ........................... .......................... ............. 3-43 3.3. Process Diagram of Turbine Steam Cycle ..................................... ................................................... .................. .... 3-44 3.4. Classification of Steam Turbines.............................. Turbines............................................ ........................... .......................... ............. 3-46 3.5. Type of Steam Flow ......................... ...................................... ........................... ........................... .......................... ........................ ........... 3-47 3.6. Axial Flow .......................... ........................................ ........................... ........................... ........................... .......................... ........................ ........... 3-47 3.7. Reverse Flow ........................... ........................................ ........................... ........................... .......................... .......................... .................... ....... 3-47 3.8. Way of Energy Conversion & Types of Blading ....................... ..................................... ...................... ........ 3-48 3.9. Impulse Blades .......................... ........................................ ........................... .......................... .......................... ........................... .................. .... 3-48 3.10. Reaction Blades ..................................... .................................................. .......................... .......................... ........................... .................. .... 3-48 3.11. Impulse Stage .......................... ........................................ ........................... .......................... .......................... ........................... .................. .... 3-48 3.12. Reaction Stage .................................... .................................................. ........................... .......................... .......................... .................... ....... 3-49 3.13. Way of Compounding ........................... ........................................ .......................... .......................... ........................... .................. .... 3-50 3.14. Compounding of Impulse Turbine Tu rbine ................................ ............................................. .......................... .................... ....... 3-50 3.15. Pressure Compounding Impulse Turbine ...................... ................................... .......................... .................... ....... 3-50 3.16. Velocity Compounded Impulse Turbine ......................... ...................................... ........................... .................. .... 3-51 3.17. Pressure-Velocity Pressure-Velocit y Compounded Co mpounded Impulse Turbine .......................... ....................................... ............... .. 3-51 3.18. Curtis Stage......................... Stage....................................... ........................... ........................... ........................... .......................... ...................... ......... 3-52 3.19. Cylinder arrangement ......................... ....................................... ........................... .......................... .......................... .................... ....... 3-52 3.20. Single cylinder construction or Single Flow Turbine. ................................... ................................... 3-53 3.21. Tandem construction or Compound Flow Turbine ............................. ........................................ ........... 3-53 3.22. Cylinder Arrangement Tandem construction .................... .................................. ........................... ............... .. 3-53 3.23. Tandem Cross-Compounding Turbine ................... ................................. ........................... .......................... ............. 3-54 3.24. Number of Stages ......................... ...................................... .......................... ........................... ........................... .......................... ............. 3-54 3.25. Exhaust Conditions ......................... ...................................... ........................... ........................... .......................... ........................ ........... 3-55 3.26. Condensing ......................... ....................................... ........................... ........................... ........................... .......................... ...................... ......... 3-55 3.27. Extraction............................... Extraction............................................ ........................... ........................... .......................... ........................... .................... ...... 3-55 3.28. Back-Pressure .......................... ........................................ ........................... .......................... .......................... ........................... .................. .... 3-55 3.29. Detailed Detail ed view vi ew of the steam s team extraction .................................. ............................................... .......................... ............. 3-56 3.30. Turbine Losses ....................... .................................... ........................... ........................... .......................... .......................... .................... ....... 3-57 3.31. Rankine Cycle ......................... ....................................... ........................... .......................... .......................... ........................... .................. .... 3-57 ................................. ....... 3-58 3.32. Steam Turbine Components and Relative Equipment’s.......................... 3.33. Turbine Supervisory Instrumentation (TSI) ................ ............................. .......................... ...................... ......... 3-65 3.34. TSI Benefits ............................. ........................................... ........................... .......................... .......................... ........................... .................. .... 3-66 3.35. Principles of Governing ........................... ........................................ .......................... ........................... ........................... ............... .. 3-67 3.36. Steam Turbine Speed Control .......................... ....................................... .......................... ........................... .................... ...... 3-67

3.37. D-EHC (Digital Electro-Hydraulic Control System) ..................................... 3-68 3.38. Main Steam Stop Valve .................................................................................. 3-68 3.39. Control Valves (Cv) ....................................................................................... 3-69 3.40. Intercept Valves .............................................................................................. 3-69 3.41. Combined Reheat Valves (CRV) ................................................................... 3-70 3.42. Turbine Turning Gear ..................................................................................... 3-70 3.43. Water induction .............................................................................................. 3-71 3.44. Atmospheric Relief Diaphragm ...................................................................... 3-73 3.45. Turbine Lube Oil System ............................................................................... 3-73 3.46. Turbine Gland Sealing .................................................................................... 3-74 3.47. Condenser ....................................................................................................... 3-74 3.48. Specification of Condenser............................................................................. 3-74 3.49. Gland Steam Condenser ................................................................................. 3-74 3.50. Vacuum System .............................................................................................. 3-75 3.51. Vacuum Breaker ............................................................................................. 3-75 3.52. Components of a Turbine Lubricating Oil System ........................................ 3-75 3.53. Turbine Protections ........................................................................................ 3-75 3.54. Steam Turbine Troubleshooting ..................................................................... 3-76 Chapter 4 Furnace Oil Decanting ................................................................................ 4-80

4.

Decanting Section .............................................................................................. 4-80 4.1. Oil Testing Lab: ................................................................................................ 4-80 4.2. Fuel Flow Cycle ............................................................................................... 4-81 4.3. Storage of Fuel ................................................................................................. 4-81 4.4. Specifications of Furnace Oil Storage Tanks ................................................... 4-82 4.5. Recirculation Pump .......................................................................................... 4-82 4.6. Purpose of RC Pumps ....................................................................................... 4-82 4.7. First Lift Pump ................................................................................................. 4-83 4.8. Second Lift Pump ............................................................................................. 4-83

Chapter 5 Boiler Section ............................................................................................... 5-85

5.

What is Boiler?................................................................................................... 5-85 5.1. Components of Boiler Drum ............................................................................ 5-85 5.2. Boiler Systems .................................................................................................. 5-85 5.3. Boiler Specification .......................................................................................... 5-86 5.4. Mini Boiler ....................................................................................................... 5-86 5.5. Mini Boiler Specification ................................................................................. 5-86

5.6. Construction of Boiler ...................................................................................... 5-87 5.7. Super Heaters .................................................................................................... 5-88 5.8. Steam Reheaters ............................................................................................... 5-89 5.9. Furnace ............................................................................................................. 5-90 5.10. Why Furnace is Important? ............................................................................ 5-92 5.11. Types of Furnace ............................................................................................ 5-92 5.12. Furnace Draft .................................................................................................. 5-92 5.13. Natural Draft ................................................................................................... 5-92 5.14. Mechanical Draft ............................................................................................ 5-92 5.15. What could we do when the Unit is to be running at minimum load? ........... 5-93 5.16. Gas Recirculation Fan (G.R.C Fan) ............................................................... 5-93 5.17. Advantages of G.R.C Fan ............................................................................... 5-93 5.18. Boiler Soot Blower System ............................................................................ 5-93 5.19. Super Heater Soot Blower System ................................................................. 5-93 5.20. R.A.H Soot Blower System ............................................................................ 5-93 5.21. Economizer Shot Blasting .............................................................................. 5-93 5.22. Flue Gas Cycle ............................................................................................... 5-94 5.23. Furnace Safeguard Supervisory System (FSSS) ............................................ 5-95 5.24. Burners............................................................................................................ 5-95 5.25. Components of Burner ................................................................................... 5-96 5.26. Combustion Air .............................................................................................. 5-96 5.27. Combustion Air Cycle Description ................................................................ 5-97 5.28. What is R.A.H and which purpose it is used? ................................................ 5-97 5.29. Economizer ..................................................................................................... 5-98 Chapter 6 Cooling Tower Section ................................................................................ 6-99

6.

What is Cooling Tower? .................................................................................... 6-99 6.1. Classification of Cooling Tower ...................................................................... 6-99 6.2. Cooling Tower Section of GENCO-III ............................................................ 6-99 6.3. Condensate Water Cycle ................................................................................ 6-100

Chapter 7 Electrical Section ....................................................................................... 7-102

7.

Generator .......................................................................................................... 7-102 7.1. Working Principle .......................................................................................... 7-102 7.2. Synchronous Generator .................................................................................. 7-103 7.3. Some problems with slip rings and brushes. .................................................. 7-104 7.4. The Speed of Rotation of a Synchronous Generator ...................................... 7-104

7.5. Excitation of Generator .................................................................................. 7-105 7.6. Separately Excited Generator ......................................................................... 7-105 7.7. Self-Excited Generator ................................................................................... 7-105 7.8. Synchronous Generator in TPS ...................................................................... 7-105 7.9. Exciter generator ............................................................................................ 7-105 7.10. Cooling System of Turbo Generator ............................................................ 7-106 7.11. Stator cooling ................................................................................................ 7-106 7.12. Rotor Cooling ............................................................................................... 7-106 7.13. Protections of Generator ............................................................................... 7-107 7.14. Longitudinal differential current protection ................................................. 7-107 7.15. Lateral differential current protection .......................................................... 7-107 7.16. Earth fault protection of stator winding ....................................................... 7-107 7.17. Differential protection of the unit ................................................................. 7-107 7.18. Negative sequence current protection .......................................................... 7-107 7.19. Over current protection against overloading of generator............................ 7-107 7.20. External symmetrical short circuit protection .............................................. 7-107 7.21. Protection against asynchronous mode, when excitation loss ...................... 7-107 7.22. Protection of generator rotor against overloading ........................................ 7-108 7.23. Earth fault protection in one point of excitation circuit ............................... 7-108 7.24. Protection against voltage increase at generator at idle operation ............... 7-108 7.25. Zero sequence current protection ................................................................. 7-108 7.26. Differential protection of the exciter ............................................................ 7-108 7.27. Over current protection of exciter against external short circuit .................. 7-108 7.28. Switch Yard .................................................................................................. 7-108 7.29. Circuit Breaker ............................................................................................. 7-109 7.30. The Necessary Capabilities of Breaker: ....................................................... 7-109 Chapter 8 Water Treatment Section ......................................................................... 8-111

8.1. Hydrogen Plant ............................................................................................... 8-111 8.2. DC Power Supply ........................................................................................... 8-112 8.3. Electrolyzer..................................................................................................... 8-112 8.4. Separating Column ......................................................................................... 8-112 8.5. Gas Scrubber................................................................................................... 8-112 8.6. Dryer ............................................................................................................... 8-112 8.7. Receiver Tanks ............................................................................................... 8-112 8.8. Demineralization plant ................................................................................... 8-112

8.9. Mechanical Clarifier filters............................................................................. 8-113 8.10. Cation filter ................................................................................................... 8-113 8.11. Decarbonized exhaust ................................................................................... 8-113 8.12. Anion filter ................................................................................................... 8-113 8.13. Cation 2nd filter ............................................................................................ 8-113 8.14. Storage tanks................................................................................................. 8-113 8.15. Water treatment ............................................................................................ 8-114 8.16. Installed Capacity in Pakistan (GW & Percentage) ..................................... 8-114 8.17. Cost of Electricity ......................................................................................... 8-115 8.18. Generation Data ............................................................................................ 8-115 Chapter 9 QadBros Engineering Services ................................................................. 9-118

9.

Introduction ...................................................................................................... 9-118 9.1. QADRI BROTHERS (PVT) LTD. (Unit-1) .................................................. 9-118 9.2. QADRI BROTHERS (PVT) LTD. (Unit-2) .................................................. 9-119 9.3. QADCAST (PVT) LTD. ................................................................................ 9-119 9.4. QADRI FOUNDRY (PVT) LTD. .................................................................. 9-119 9.5. QADBROS ENGINEERING (PVT) LTD. .................................................... 9-119 9.6. QADRI ENGINEERING (PVT) LTD ........................................................... 9-119 9.7. QADRI FORGE (subsidiary of QADRI BROTHER ..................................... 9-119 9.8. QADRI SONS (PVT) LTD ............................................................................ 9-120 9.9. KASHIF TRADEHOUSE (PVT) LTD .......................................................... 9-120 9.10. Departments.................................................................................................. 9-120 9.11. Facilities........................................................................................................ 9-120 9.12. Products ........................................................................................................ 9-120 9.13. Quality Certification ..................................................................................... 9-121 9.14. Scope ............................................................................................................ 9-121

Chapter 10 Production, Planning & Control ......................................................... 10-122

10.

Introduction .................................................................................................... 10-122

10.1. Production, Planning & Control Sections .................................................. 10-122 10.2. Project Planning .......................................................................................... 10-122 10.3. Core Planning ............................................................................................. 10-123 10.4. Material Handling ....................................................................................... 10-123 10.5. Material Management Group ..................................................................... 10-123 10.6. General Stores ............................................................................................ 10-124 10.7. Production Technology Department........................................................... 10-124

10.8. Dispatch Cell .............................................................................................. 10-124 10.9. Work Procedure of PPC ............................................................................. 10-125 Chapter 11 Fabrication Shop .................................................................................. 11-126

11.

Introduction .................................................................................................... 11-126

11.1. Fabrication Techniques .............................................................................. 11-126 11.2. Planning and Control (CTC) ...................................................................... 11-127 11.3. Marking and Layout Section ...................................................................... 11-127 11.4. Marking Section ......................................................................................... 11-128 11.5. Marking Tools ............................................................................................ 11-128 11.6. Surface plate or marking out table.............................................................. 11-128 11.7. Angle Plates ................................................................................................ 11-128 11.8. Scriber......................................................................................................... 11-128 11.9. Height Gauge or Scribing Block ................................................................ 11-128 11.10. Surface Gauge .......................................................................................... 11-128 11.11. Marking Blue ............................................................................................ 11-128 11.12. Protractor .................................................................................................. 11-128 11.13. Tri-Square ................................................................................................. 11-128 11.14. Punches ..................................................................................................... 11-128 11.15. Dividers or Measuring Compass .............................................................. 11-129 11.16. Cutting Section or Flame Cutting ............................................................. 11-129 11.17. What is flame cutting ................................................................................ 11-129 11.18. Process ...................................................................................................... 11-129 11.19. Flame Cutting Equipment’s ...................................................................... 11-129

11.20. Joining Operations .................................................................................... 11-130 11.21. Soldering................................................................................................... 11-130 11.22. Brazing...................................................................................................... 11-130 11.23. Welding .................................................................................................... 11-130 11.24. Classification of Welding ......................................................................... 11-130 11.25. SMAW ...................................................................................................... 11-130 11.26. Purpose of Flux on Welding Electrode .................................................... 11-131 11.27. GTAW ...................................................................................................... 11-131 11.28. Polarity of Current in GTAW ................................................................... 11-132 11.29. GMAW ..................................................................................................... 11-132 11.30. SAW ......................................................................................................... 11-132 11.31. Recommendations .................................................................................... 11-132

Chapter 12 Machine Shop ....................................................................................... 12-133

12.

Introduction .................................................................................................... 12-133

12.1. Five M’s ...................................................................................................... 12-133

12.2. Division of Shop ......................................................................................... 12-133 12.3. Sequence of Operation ............................................................................... 12-133 12.4. Explanation ................................................................................................. 12-134 12.5. Raw Materials Used in Machine Shop ....................................................... 12-134 12.6. Products Seen in Machine Shop ................................................................. 12-134 12.7. Tools used in Machine Shop ...................................................................... 12-135 12.8. Machines/Equipment installed in Machine Shop ....................................... 12-135 12.9. Machining Operations ................................................................................ 12-136 12.10. Machining ................................................................................................. 12-136 12.11. Turning and Related Operations ............................................................... 12-136 12.12. Turning ..................................................................................................... 12-136 12.13. Facing ....................................................................................................... 12-136 12.14. Chamfering ............................................................................................... 12-136 12.15. Threading .................................................................................................. 12-136 12.16. Lathe Machines ........................................................................................ 12-136 12.17. Methods of Holding the Work in a Lathe................................................. 12-137 12.18. Boring Machine ........................................................................................ 12-137 12.19. Vertical Boring Mill ................................................................................. 12-137 12.20. Drilling...................................................................................................... 12-137 12.21. Milling Machine and Operation ............................................................... 12-137 12.22. Basic Types of Milling Operations .......................................................... 12-138 12.23. Peripheral milling or plain milling: .......................................................... 12-138 12.24. Face milling .............................................................................................. 12-138 12.25. Shaper Machine ........................................................................................ 12-138 12.26. Planar Machine ......................................................................................... 12-138 12.27. Pedestal Grinding Machine ...................................................................... 12-138 12.28. Production Planning Section .................................................................... 12-138 12.29. Working .................................................................................................... 12-139 12.30. Routes ....................................................................................................... 12-139 12.31. Route 1 ...................................................................................................... 12-139 12.32. Route 2 ...................................................................................................... 12-139 12.33. Route 3 ...................................................................................................... 12-139

12.34. Recommendations .................................................................................... 12-140 Chapter 13 Heat Treatment Shop ........................................................................... 13-141

13.

Introduction .................................................................................................... 13-141

13.1. Selective Surface Hardening / Case Hardening ......................................... 13-141 13.2. Flame hardening ......................................................................................... 13-141 13.3. Recommendations ...................................................................................... 13-141 Chapter 14 Non-Destructive Testing ...................................................................... 14-142

14.

Introduction .................................................................................................... 14-142

14.1. NDT Techniques ........................................................................................ 14-142 14.2. Ultrasonic Testing (UT) ............................................................................. 14-142 14.3. Probe types ................................................................................................. 14-143 14.4. Advantages ................................................................................................. 14-143 14.5. Limitations .................................................................................................. 14-143 14.6. Magnetic Particle Testing (MPT) ............................................................... 14-143 14.7. Dye Penetrating Test (DPT) ....................................................................... 14-143 14.8. Principle ...................................................................................................... 14-143 14.9. Inspection steps .......................................................................................... 14-144 14.10. Universal Crack Depth Meter X-RT-705 ................................................. 14-144 14.11. Recommendations .................................................................................... 14-144 Chapter 15 Material Testing ................................................................................... 15-145

15.

Introduction .................................................................................................... 15-145

15.1. Test Performed in MTL .............................................................................. 15-145 15.2. Quick analysis ............................................................................................ 15-146 15.3. Metallography............................................................................................. 15-146 15.4. Process Diagram of Metallographic Testing .............................................. 15-147 15.5. Chemical Analysis ...................................................................................... 15-147 15.6. which Materials can be tested??? ............................................................... 15-147 15.7. Mechanical Testing .................................................................................... 15-148 15.8. Impact Testing Machine ............................................................................. 15-148 15.9. Hardness Tester .......................................................................................... 15-148 Chapter 16 Assembly Shop ...................................................................................... 16-149

16.

Introduction .................................................................................................... 16-149

16.1. Temporary Fastening .................................................................................. 16-149 16.2. Permanent Fastening .................................................................................. 16-149

16.3. Assembly .................................................................................................... 16-149 16.4. Why we prefer mechanical assembly? ....................................................... 16-149 16.5. Threaded fasteners ...................................................................................... 16-150 16.6. Screw, Bolts and Nuts ................................................................................ 16-150 16.7. Washer ........................................................................................................ 16-150 16.8. Assembly Shop ........................................................................................... 16-150 16.9. Tools and Methods for threaded fasteners ................................................. 16-151 16.10. Rivets ........................................................................................................ 16-151 16.11. Types of Fittings ....................................................................................... 16-151 16.12. Fits ............................................................................................................ 16-151 16.13. Clearance fit .............................................................................................. 16-151 16.14. Interference fit .......................................................................................... 16-151 16.15. Transition fit ............................................................................................. 16-152 16.16. Assembly Systems .................................................................................... 16-152 16.17. Hole Basis System .................................................................................... 16-152 16.18. Shaft Basis System ................................................................................... 16-152 16.19. Recommendations .................................................................................... 16-152 Chapter 17 Quality Control Department ............................................................... 17-153

17.

Quality Control Procedures ............................................................................ 17-153

17.1. Hold point (H) ............................................................................................ 17-154 17.2. Witness Point (W) ...................................................................................... 17-154 17.3. Spot Witness (SW) ..................................................................................... 17-154 17.4. Review (R) .................................................................................................. 17-154

List of Figures Figure 1-1 hydroelectric power ....................................................................................................1-19 Figure 1-2 Coal Fired Thermal Power Plant ................................................................................1-26 Figure 1-3 Gas Turbine Combined Cycle ....................................................................................1-27 Figure 2-1 Flow Diagram of Energy Conversion ........................................................................2-32 Figure 2-2 Gate Type Furnace .....................................................................................................2-34 Figure 2-3 Regenerative Air PreHeater .......................................................................................2-39 Figure 2-4 Thermal Cycle ............................................................................................................ 2-41 Figure 3-1 Steam Cycle ...............................................................................................................3-43 Figure 3-2 Turbine Steam Cycle ..................................................................................................3-44 Figure 3-3 Steam Turbine Cross-Section View ........................................................................... 3-45 Figure 3-4 Steam flow ................................................................................................................. 3-46 Figure 3-5 Type of Steam Flow ...................................................................................................3-47 Figure 3-6. Reverse Flow .............................................................................................................3-47 Figure 3-7 Impulse Blades ...........................................................................................................3-48 Figure 3-8 Reaction Blades.........................................................................................................3-48 Figure 3-9 Impulse Stage ............................................................................................................3-49 Figure 3-10 Reaction Stage.........................................................................................................3-49 Figure 3-11 Impulse & Reaction Turbine ....................................................................................3-50 Figure 3-12 Pressure Compounding Impulse Turbine ................................................................3-51 Figure 3-13 Velocity Compounded Impulse Turbine ..................................................................3-51 Figure 3-14 Pressure-velocity Compounded Impulse Turbine ....................................................3-52 Figure 3-15 Curtis stage ...............................................................................................................3-52 Figure 3-16 Single cylinder turbines............................................................................................ 3-53 Figure 3-17 Three Cylinder Turbine ............................................................................................3-54 Figure 3-18 cross compound turbines .......................................................................................... 3-54 Figure 3-19 Exhaust Conditions ..................................................................................................3-55 Figure 3-20 TS Diagram for Rankine Cycle ................................................................................3-58 Figure 3-21 Steam Turbine Components .....................................................................................3-59 Figure 3-22 The casings of turbine ..............................................................................................3-60 Figure 3-23 The casings of turbine ..............................................................................................3-61 Figure 3-24 Steam Turbine Blades ..............................................................................................3-61 Figure 3-25 Stationary Blade or Diaphragm................................................................................3-62 Figure 3-26 Various root fixing shapes .......................................................................................3-63 Figure 3-27 labyrinth seal ............................................................................................................3-64

Figure 3-28 Turbine Supervisory Instrumentation ......................................................................3-65 Figure 3-29 main stop valve ........................................................................................................3-69 Figure 3-30 The control valves ....................................................................................................3-69 Figure 3-31 combined reheat valves ............................................................................................3-70 Figure 3-32 motor driven turning gear.........................................................................................3-71 Figure 3-33 atmospheric relief diaphragm...................................................................................3-73 Figure 4-1. Fuel Flow Cycle ........................................................................................................4-81 Figure 4-2 RC (Recirculation) pump ...........................................................................................4-82 Figure 4-3 furnace oil from the main heaters...............................................................................4-84 Figure 5-1 Boiler Drum ...............................................................................................................5-88 Figure 5-2 Attemperator. .............................................................................................................5-89 Figure 5-3 steam reheaters ...........................................................................................................5-90 Figure 5-4 Furnace ....................................................................................................................... 5-90 Figure 5-5 Furnace Gate Type .....................................................................................................5-91 Figure 5-6 Flue gases ................................................................................................................... 5-94 Figure 5-7 Flue gases ................................................................................................................... 5-95 Figure 5-8 Burner ......................................................................................................................... 5-96 Figure 5-9 regenerative air heater ................................................................................................5-97 Figure 5-10 regenerative air heater ..............................................................................................5-98 Figure 5-11 Economizer ..............................................................................................................5-98 Figure 6-1 Cooling classification .................................................................................................6-99 Figure 6-2 taleeri canal ..............................................................................................................6-100 Figure 6-3 C.W water cycle .......................................................................................................6-101 Figure 7-1 synchronous generator ............................................................................................. 7-103 Figure 8-1 Hydrogen plant ......................................................................................................... 8-111 Figure 8-2 Demineralized plant .................................................................................................8-113 Figure 10-1 Material requirement planning .............................................................................10-124 Figure 10-2 PPC ....................................................................................................................... 10-125 Figure 11-1 Metal fabrication .................................................................................................. 11-126 Figure 11-2 Central Technical Cell.......................................................................................... 11-127 Figure 11-3 Shielded metal arc welding ..................................................................................11-131 Figure 15-1 Metallographic Testing ........................................................................................ 15-147

List of Tables Table 2-1 ......................................................................................................................................2-30 Table 2-2 ......................................................................................................................................2-33 Table 2-3 ......................................................................................................................................2-36 Table 2-4 ......................................................................................................................................2-37 Table 2-5 ......................................................................................................................................2-37 Table 2-6 ......................................................................................................................................2-38 Table 2-7 ......................................................................................................................................2-38 Table 3-1 ......................................................................................................................................3-57 Table 3-2 ......................................................................................................................................3-74 Table 3-3 ......................................................................................................................................3-78 Table 3-4 ......................................................................................................................................3-79 Table 4-1 ......................................................................................................................................4-82 Table 4-2 ......................................................................................................................................4-83 Table 4-3 ......................................................................................................................................4-84 Table 5-1 ......................................................................................................................................5-86 Table 5-2 ......................................................................................................................................5-87 Table 5-3 ......................................................................................................................................5-96

List of Graphs Graphs 8-1..................................................................................................................................8-114 Graphs 8-2..................................................................................................................................8-115 Graphs 8-3..................................................................................................................................8-115 Graphs 17-1..............................................................................................................................17-154 Graphs 17-2..............................................................................................................................17-155 Graphs 17-3..............................................................................................................................17-155 Graphs 17-4..............................................................................................................................17-156 Graphs 17-5..............................................................................................................................17-156 Graphs 17-6..............................................................................................................................17-157 Graphs 17-7..............................................................................................................................17-157

Chapter

1 1. Introduction Whenever, we are going to study about the power plants, we must know about the sources of energy. In this unit, we will be discussing the concepts of various power plants, their advantages and disadvantages. Fuels used in the power plants. The important fuels used in the power plants like, coal, diesel, steam, uranium, etc. are also clearly described here. A complex of structures, machinery, and associated equipment for generating electric energy from another source of energy, such as nuclear reactions or a hydroelectric dam. Also called generating station, power station. A power plant or a power generating station, is basically an industrial location that is utilized for the generation and distribution of electric power in mass scale, usually in the order of several 1000 Watts. These are generally located at the sub-urban regions or several kilometers away from the cities or the load centers, because of its requisites like huge land and water demand, along with several operating constraints like the waste disposal etc. For this reason, a power generating station has to not only take care of efficient generation but also the fact that the power is transmitted efficiently over the entire distance. And that’s why, the transformer switch yard to regulate

transmission voltage also becomes an integral part of the power plant.

1.1. Objectives After studying this unit, you should be able to 

understand the concept of power plant.



understand the types of power plants.



know the types of fuels, and describes the main components of power plants.

2. Sources of Energy – Fuels There are many different ways in which the abundance of energy around us can be stored,

converted, and amplified for our use. To help understand the key energy sources that will play an important role in the world’s future, it is required to familiarize with some of the history, theory,

economics, and problems of the various types of energy. The energy sources have been split into three categories: fossil fuels, renewable sources, and nuclear sources. The fossil fuels here are coal,

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Chapter 1 Power Resources and Power Plants

petroleum, and natural gas. The renewable energy sources are solar, wind, hydroelectric, biomass, and geothermal power. The nuclear-powered sources are fission and fusion.

1.2. Types of Fuels 1.3. Fossil fuels Fossil fuels have been a widely used source of energy ever since the Industrial Revolution just before the dawn of the 20th century. Fossil fuels are relatively easy to use to generate energy because they only require a simple direct combustion. However, a problem with fossil fuels is their environmental impact. Not only does their excavation from the ground significantly alter the environment, but their combustion leads to a great deal of air pollution. The theory behind fossil fuels is actually quite simple. Burning coal, natural gas, and petroleum

releases energy stored in the fuel as heat. The energy contained by the fuels is derived from the energy of the sun. The heat that is recovered upon combustion of the fuel can be used by us in several ways. Industrial processes that require extremely high temperatures may burn a great deal of ver y pure coal known as “coke” and use the energy released to directly heat a system. Some people make use of clean burning natural gas to heat their homes. Combustion of fossil fuels can also be used to generate electricity; the fuel is burned to heat water, and the steam from the boiling water spins turbines that power a generator, thereby manufacturing electricity.

1.4. Coal About 300 million years ago, enormous ferns and other prehistoric plants were common on the swamp-like earth. When those plants died and fell to the ground, they were covered with water and they slowly decomposed. As decomposition took place in the absence of oxygen, much of the hydrogen content of the matter was eroded away, leaving a material rich in carbon. The material was compressed over the years by sand and dirt, leaving the form of carbon known as coal. The nature of coal is such that the higher the carbon content, the more cleanly and brilliantly the

coal burns. Thus “peat”, which is the state of the decomposing plants before being co mpressed, is

a weak, impure substance. The other states of coal from lowest carbon content to highest are lignite, bituminous coal, and anthracite coal. If the coal is heated and compressed even more, the result is graphite, almost completely pure carbon. Nearly all the different forms of coal are used in some way or another. For instance, peat has been used for burning in furnaces, whereas bituminous coal is used extensively for the generation of electricity. “Coke”, a very pure form of coal with high heat

content is used primarily in the steel industry, where high temperatures are required.

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1.5. Hydroelectric Man has utilized the power of water for years. Much of the growth of early colonial industry can be attributed to hydropower. Because fuel such as coal and wood were not readily available to inland cities, settlers were forced to turn to other alternatives. Falling water was ideal for powering saw mills and grist mills. As coal became a better-developed source of fuel, however, the importance of hydropower decreased. Theory Hydroelectric systems make use of the energy in running water to create electricity. In coal

and natural gas systems, a fossil fuel is burned to heat water. The steam pressure from the boiling water turns propellers called turbines. These turbines spin coils of wire between magnets to produce electricity. Hydro powered systems also make use of turbines to generate electrical power; however, they do so by using the energy in moving water to spin the turbines. Water has kinetic energy when it flows from higher elevations to lower elevations. In larger scale hydroelectric plants, large volumes of water are contained by dams near the generator and turbines. The “foreba y” is a storage

area for water that must be deep enough that the penstock is completely submerged. The water is allowed to flow into the electricity-generating system through a passage called the penstock. The controlled high-pressure water spins the turbines, allowing the generator to produce an electric current. The powerhouse contains and protects the equipment for generating electricity. The high pressure water exits the system through a draft tube. The fish ladder attempts to minimize the environmental impact of hydroelectric systems by providing a path for migrating fish to take.

1.6. Types of Hydroelectric Power Plants 1.7. Micro-Scale As their name implies, micro-hydroelectric plants are the smallest type of hydroelectric energy systems. They generate between one kilowatt and one megawatt of power. The main application for these hydro systems is in small, isolated villages in developing countries. They are ideal for powering smaller services such as the operation of processing machines.

1.8. Small-Scale Small hydropower systems can supply up to 20 megawatts of energy. These systems are relatively inexpensive and reliable. They have the potential to provide electricity to rural areas in developing countries throughout the world. Small systems are especially important to countries that may not be able to afford the costs of importing fossil fuels such as petroleum from other countries.

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1.9. Run-of-the-River In some areas of the world, the flow rate and elevation drops of the water are consistent enough that hydroelectric plants can be built directly in the river. The water passes through the plant without greatly changing the flow rate of the river. In many instances a dam is not required, and therefore the hydroelectric plant causes minimal environmental impact on its surroundings. However, one problem with run-of-the-river plants is the obstruction of fish and other aquatic animals. This and other problems are discussed in the next section.

Figure 1-1 hydroelectric power

1.10. Problems with Hydroelectric Power Although hydroelectric power is admittedly one of the cleanest and most environmentally-friendly sources of energy, it too has the capability to alter or damage its surroundings. Among the main problems that have been demonstrated by hydroelectric power is significant change in water quality. Because of the nature of hydroelectric systems, the water often takes on a h igher temperature, loses oxygen content, experiences siltation, and gains in phosphorus and nitrogen content. Another major problem is the obstruction of the river for aquatic life. Salmon, which migrate upstream to spawn every year, are especially impacted by hydroelectric dams. Fortunately, this problem has been dealt with by the production of fish ladders. These structures provide a pathway for fish to navigate past the hydroelectric dam construction.

1.11. Advantages and Disadvantages Advantages 

Inexhaustible fuel source



Minimal environmental impact



Viable source--relatively useful levels of energy production



Can be used throughout the world

Disadvantages 

Smaller models depend on availability of fast flowing streams or ri vers.



Run-of-the-River plants can impact the mobility of fish and other river life.

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Note: Building a fish ladder can lessen this negative aspect of hydroelectric power.

1.12. Solar The name solar power is actually a little misleading. In fact, most of the energy known to man is derived in some way from the sun. When we burn wood or other fuels, it releases the stored energy of the sun. In fact, there would be no life on earth without the sun, which provides energy needed for the growth of plants, and indirectly, the existence of all animal life. The so lar energy scientists are interested in energy obtained through the use of solar panels. Although the field of research dealing with this type of solar power is relatively new, one should bear in mind that man has known about the energy of the sun for thousands of years. Theory There are two ways in which solar power can be converted to energy. The first, known as

“solar thermal applications”, involve using the en ergy of the sun to directly heat air or a liquid. The second, known as “photoelectric applications”, involve the use of photovoltaic cells to convert solar

energy directly to electricity. There are two types of solar thermal collectors. The first, known as flat plate collectors, contain absorber plates that use solar radiation to heat a carrier fluid, either a liquid like oil or water, or air. Because these collectors can heat carrier fluids to around 80 ° C, they are suited for residential applications. The second type of solar collectors is known as concentrating collectors. These panels are intended for larger-scale applications such as air conditioning, where more heating potentials required. The rays of the sun from a relatively wide area are focused into a small area by means of reflective mirrors, and thus the heat energy is concentrated. This method has the potential to heat liquids to a much higher temperature than flat plate collectors can alone. The heat from the concentrating collectors can be used to boil water. The steam can then be used to power turbines attached to generators and produce electricity, as in wind and hydroelectric power systems. Photovoltaic cells depend on semiconductors such as silicon to directly convert solar energy to electricity. Because these types of cells are low-maintenance, they are best suited for remote applications. Solar power has an exciting future ahead of it. Because solar power utilizes the sun's light, a ubiquitous resource (a resource that is everywhere), solar panels can be attached to moving objects, such as automobiles, and can even be used to power those objects. Solar powered cars are being experimented with more and more frequently now.

1.13. Problems with Solar Power Solar power is actually one of the cleanest methods of energy production known. Because solar panels simply convert the energy of the sun into energy that mankind can use, there are no harmful byproducts or threats to the environment. One major concern is the cost of solar power. Solar panels (accumulators) are not cheap; and because they are constructed from fragile materials (semiconductors, glass, etc.), they must constantly be maintained and often replaced. Further, since

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each photovoltaic panel has only about 40% efficiency, single solar panels are not sufficient power producers. However, this problem has been offset by the gathering together of many large panels acting in accord to produce energy. Although this setup takes up much more space, it does generate much more power.




Inexhaustible fuel source. No pollution.



Often an excellent supplement to other renewable sources.



Versatile is used for powering items as diverse as solar cars and satellites.

Disadvantages 

Very diffuse source means low energy production – large numbers of solar panels (and thus large land areas) are required to produce useful amounts of heat or electricity.



Only areas of the world with lots of sunlight are suitable for solar power generation.

1.15. Wind Mankind has made use of wind power since ancient times. Wind has powered boats and other sea craft for years. Further, the use of windmills to provide power for the accomplishment of agricultural tasks has contributed to the growth of civilization. This important renewable energy source is starting to be looked at again as a possible source of clean, cheap energy for years to come.

1.16. Problems One of the main problems with wind power is the space that is used up by the so-called wind farms. In some cases, the space taken up can seriously alter the environment. The good news is that although wind farms require a great deal of square mileage, there is quite a bit of space between the actual wind machines. This space can be used for agricultural purposes. Another problem with wind power is that relatively speaking, it does not generate very much energy for the price. Perhaps this setback is made up for in friendliness to the environment.






Inexhaustible fuel source. No pollution. Often an excellent supplement to other renewable sources.

Disadvantages 

Very diffuse source means low energy production – large numbers of

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Chapter 1 Power Resources and Power Plants 

wind generators (and thus large land areas) are required to produce



useful amounts of heat or electricity.



Only areas of the world with lots of wind are suitable for wind power



generation.



Relatively expensive to maintain.

1.18. Geothermal The center of the earth can reach 12000 degrees Fahrenheit. Just imagine if we could tap that heat for our own use. Well, geothermal systems do just that. Convection (heat) currents travel quite near the surface in some parts of the world. Theory The earth’s crust is heated by the decay of radioactive elements. The heat is carried by

magma or water beneath the earth's surface. Some of the heat reaches the surface and manifests itself in geysers and hot springs throughout the world. Geothermal power can be used to directly heat buildings. Further, the pressurized steam from superheated water beneath the earth’s surface

can be used to power turbines and thus generate electricity. Although geothermal power seems ideal in that it is naturally occurring and does not require structures to trap or collect the energy (as in solar panels or windmills), it does have limitations. The greatest drawback is that naturally occurring geothermal vents are not widely available. Artificial vents have been successfully drilled in the ground to reach the hot rocks below and then injected with water for the production of steam. However, oftentimes the source of heat is far too deep for this method to work well. Nor can geothermal power realistically generate enough electricity for the entire country or any large industrialized nation. A good-sized hot spring can power at most a moderate sized city of around 50,000 people. And there just isn’t enough viable

hot springs to power all the cities in any large country.




Theoretically inexhaustible energy source. No pollution.



Often an excellent supplement to other renewable sources.



Does not require structures such as solar panels or windmills to collect the energy – can be directly used to heat or produce electricity (thus very cheap).

Disadvantages 

Not available in many locations.



Not much power per vent.

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1.20. Ocean Energy 1.21. Tidal Energy Tides are caused by the gravitational pull of the moon and sun, and the rotation of the earth. Near shore, water levels can vary up to 40 feet. Only a few locations have good inlets and a large enough tidal range- about 10 feet- to produce energy economically. The simplest generation system for tidal plants involves a dam, known as a barrage, across an inlet. Sluice gates on the barrage allow the tidal basin to fill on the incoming high tides and to empty through the turbine system on the outgoing tide, also known as the ebb tide. There are two-way systems that generate electricity on both the incoming and outgoing tides. Tidal fences can also harness the energy of tides. A tidal fence has vertical axis turbines mounted in a fence. All the water that passes is forced through the turbines. They can be used in areas such as channels between two landmasses. Tidal fences have less impact on the environment than tidal barrages although they can disrupt the movement of large marine animals. They are cheaper to install than tidal barrages too. Tidal turbines are a new technology that can be used in many tidal areas. They are basically wind turbines that can be located anywhere there is strong tidal flow. Because water is about 800 times denser than air, tidal turbines will have to be much sturdier than wind turbines. They will be heavier and more expensive to build but will be able to capture more energy.

1.22. Wave Energy Waves are caused by the wind blowing over the surface of the ocean. There is tremendous energy in the ocean waves. The total power of waves breaking around the world’s coastlines is estimated

at 2-3 million megawatts. The west coasts of the US and Europe and the coasts of Japan and New Zealand are good sites for harnessing wave energy. One way to harness wave energy is to bend or focus the waves into a narrow channel, increasing their power and size. The waves can then be channeled into a catch basin or used directly to spin turbines. There are no big commercial wave energy plants, but there are a few small ones. Small, on-shore sites have the best potential for the immediate future; they could produce enough energy to power local communities. Japan, which imports almost all of its fuel, has an active wave-energy program.

1.23. Nuclear Energy In a universe, energy and matter have a common origin. None the energy nor the matter can be created or destroyed; instead they just change their state. As well, they are convertible to each other. Albert Einstein was the first man who explained this relation by the well known formula:

 = 

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This equation defines:

 () equals

to

 ()

times

 (     ). By looking in

close, we may find the enormous energy exist in a small piece of material. The name of atom comes from Greek language, referring to smallest part of nature. Nowadays we have a better knowledge on atom structure, and we know a nucleus, surrounded by electrons, form the atoms. This structure is somehow similar to our solar system.

1.24. Nuclear Fission Any try for splitting a part a nucleus will cause a tremendous energy be released. This energy would be released in both forms of heat and light. In a harnessed, controlled way of doing this, a useful energy for producing electricity is possible. Doing this at once would result to a big explosion, as seen in an automatic bomb. In a nuclear power plant, uranium is the element used as fuel. Uranium is found in many parts of the world but in a low quantity. It is loaded in to the reactor in a tiny pallet form inside long rods. Fission meaning splitting a part is what happens in a reactor. Here uranium atoms are split in a paced controlled chain of reactions. Inside a reactor the intensity of crashes is harnessed by inserting-taking of control roads. In an atomic bomb a different process occurs, by using almost pure pieces of elements-uranium 235 or plutonium, in a precise mass and shape, burning them together in a great force. As we see there is no requisite like this in a reactor. Byproducts of such reactions are radioactive materials. If released, they would be gravely harmful. Knowing this, strong structures must keep the materials in the case of any accident. The released heat energy would be used for boiling water in the core of reactor. So instead of burning fuel, we may use the heat of reactor core. By sending the hot water around the nuclear to the heat exchanger section, water filled pipes produce steam needed for steam turbine.

1.25. Nuclear Fusion In another form of nuclear reaction, joining of smaller nuclei makes a larger nucleus. Such a process in sun changes the hydrogen atoms to helium. The result heat and light we receive in earth. In a more detailed explanation, two different types of atoms, deuterium and tritium, combine to make a helium plus and extra particle called neutron. There has been a fierce competition among scientists, but to their frustration, they have yet trouble in controlling reaction in a closed space. The advantage of fusion is its abundance of supply (hydrogen) as well as its less radioactive material than fission.

1.26. Classification of Power Plants Power plants are classified by the type of fuel and the type of prime mover installed.

Chapter 1-24 of 157


1.27. By Fuel 

In thermal power stations, mechanical power is produced by a heat engine, which transforms thermal energy, often from combustion of a fuel, into rotational energy





Nuclear power plants use a nuclear reactor’s heat to operate a steam turbine generator.

Fossil fuel powered plants may also use a steam turbine generator or in the case of Natural gas fired plants may use a combustion turbine.



Geothermal power plants use steam extracted from hot underground rocks.



Renewable energy plants may be fueled by waste from sugar cane, municipal solid waste, landfill methane, or other forms of biomass.



In integrated steel mills, blast furnace exhaust gas is a low-cost, although low-energydensity, fuel.



Waste heat from industrial processes is occasionally concentrated enough to use for power generation, usually in a steam boiler and turbine.

1.28. By Prime Mover 

Steam turbine plants use the pressure generated by expanding steam to turn t he blades of a turbine.





Gas turbine plants use the heat from gases to directly operate the turbine. Natural-gas fueled turbine plants can start rapidly and so are used to supply peak energy during periods of high demand, though at higher cost than base-loaded plants.



Combined cycle plants have both a gas turbine fired by natural gas, and a steam boiler and steam turbine which use the exhaust gas from the gas turbine to produce electricity. This greatly increases the overall efficiency of the plant, and newest base load power plants are combined cycle plants fired by natural gas.



Internal combustion Reciprocating engines are used to provide power for isolated communities and are frequently used for small cogeneration plants.



Hospitals, office buildings, industrial plants, and other critical facilities also use them to provide backup power in case of a power outage. These are usually fueled by diesel oil, heavy oil, natural gas and landfill gas.



Micro turbines, stirling engine and internal combustion reciprocating engines are low cost solutions for using opportunity fuels, such as landfill gas, digester gas from water treatment plants and waste gas from oil production.

1.29. Steam Turbine Power Station The conversion from coal to electricity takes place in three stages:

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Chapter 1 Power Resources and Power Plants Stage 1 The first conversion of energy takes place in the boiler. Coal is burnt in the boiler furnace

to produce heat. Carbon in the coal and Oxygen in the air combine to produce Carbon Dioxide ( ) and heat.

Figure 1-2 Coal Fired Thermal Power Plant Stage 2 The second stage is the thermodynamic process: a) The heat from combustion of the coal boils water in the boiler to produce steam. In modern

power plant, boilers produce steam at a high pressure and temperature. b) The steam is then piped to a turbine. c) The high pressure steam impinges and expands across a number of sets of blades in the turbine. d) The impulse and the thrust created rotate the turbine. e) The steam is then condensed and pumped back into the boiler to repeat the cycle. Stage 3 In the third stage, rotation of the turbine rotates the generator rotor to produce electricity

based of Faraday’s Principle on electromagnetic induction.

1.30. Gas Turbine Power Station The schematic arrangement of a gas turbine power plant is shown The main components of plants are: 1. Compressor 2. Regenerator 3. Combustion Chamber 4. Gas Turbine 5. Alternator 6. Starting motor

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Figure 1-3 Gas Turbine Combined Cycle

1.31. Pollution 1.32. Global Warming Scientists believe that global warming is caused by the Greenhouse effect. The greenhouse effect describes the accumulation of carbon dioxide in our earth’s atmosphere. A layer

of gas forms that traps heat inside the atmosphere, thereby acting as the glass ceiling of a greenhouse. Because heat is trapped by the carbon dioxide, it is believed that the earth is slowly warming. A potential danger of global warming is the melting of the so-called polar ice caps at the north and south poles. This occurrence would cause the ocean level to rise and perhaps flood many coastal cities.

1.33. The Advent of Fossil Fuels Before humans were around on the earth, there was a relatively even recycling of carbon dioxide and oxygen. Plants require carbon dioxide to live, and they emit oxygen in return. Animals, on the other hand, need oxygen, but exhale carbon dioxide. But as humans began to burn fossil fuels to create energy (especially beginning just before the 20th century during the Industrial Revolution), more and more carbon dioxide was emitted into the air until the balance was slowly destroyed.

1.34. How Do Fossil Fuels and Biomass Pollute? All fossil fuels and biomasses consist of carbon and hydrogen atoms. When these fu els are burned, or combusted, carbon atoms unite with oxygen in the air to form carbon dioxide:

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1.35. Other Polluting Byproducts of Fossil Fuel and Biomass Burning Carbon dioxide is not the only byproduct of direct combustion of fuel. Small particulates that can become imbedded in the human respiratory system are also emitted. Particulates can cause coughing and damage to the lungs. Further, they can lead to cancer and lung disease. Carbon monoxide is produced when less oxygen is available in the immediate area. Carbon monoxide is more directly harmful to humans because it is odorless, colorless, and reduces the body’s ability to transport

oxygen. This leads to fatigue, nausea, and headaches.

1.36. The Spectrum of Pollution Materials on the low end of the energy scale such as wood and charcoal create the most pollution. Sources on the high end of the energy scale, such as natural gas burn ver y cleanly resulting in less air pollution.

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Chapter

2 2. Northern Power Generation Company Limited (GENCO-III) NPGCL Muzaffargarh is located in the middle of the country between the River Indus and River Chenab, 2.5 Km to North-West of Muzaffargarh Town in District Muzaffargarh. The nearest Airport facility is at Multan at a distance of 45 Km North-East of Muzaffargarh.

2.1.

Thermal Power Station

A thermal power station is a power plant in which the prime mover is steam driven. Water is heated, turns into steam and spins a steam turbine which either drives an electrical generator or does some other work, like ship propulsion. After it passes through the turbine, the steam is condensed in a condenser and recycled to where it was heated; this is known as a Rankine cycle. The greatest variation in the design of thermal power stations is due to the different fuel sources. Some prefer to use the term energy center because such facilities convert forms of heat energy into electrical energy.

2.2. Thermal Power Station Muzaffargarh This Power Station is a vital and major thermal power generating installation connected with National grid system in Pakistan. This Power Station was constructed in different Phases having total capacity of 1370 MW. Sand Dunes of area known as Rakh Khanpur, at a distance of 6 km. from Muzaffargarh City, is located Thermal Power Complex. A few years back nobody perceived that such a desert would yield green trees, more than 1,500 families would be residing here and a Power Station will turn into a huge Power Complex. Now, with the day and night efforts of foreign as well as Pakistani engineers, technicians and workers, the complex has grown to the realities with three sky-high chimneys, being highest concrete structure in Pakistan and visible from the bridge of River Chenab, which is flowing to the east of the site at distance of 8 KM. In September, 1987 contract of supply and erection of a 3x210 MW capacity Thermal Power Station was signed with M/s. TECHNOPROMEXPORT of ex-USSR, Moscow, and 1,134 acres of government land was acquired. It consists of:

Page 2-29 of 157

Chapter 2 GENCO Thermal Power Station 3 Unit No.

Installed Capacity

Rated Capacity

Make

Commissioning Date

ST-1

210 MW

200 MW

USSR

Sep. 1993

ST-2

210 MW

200 MW

USSR

Mar. 1994

ST-3

210 MW

200 MW

USSR

Feb. 1995

ST-4

320 MW

300 MW

China

Dec. 1996

ST-5

200 MW

200 MW

China

Dec. 1995

ST-6

200 MW

200 MW

China

Dec. 1995

Fuel Type

P. Gas, F. Oil P. Gas, F. Oil P. Gas, F. Oil P. Gas, F. Oil P. Gas, F. Oil P. Gas, F. Oil

Table 2-1

Initially, about 230 acres’ land for the Power Station and 164 acres for residential colony

was leveled and subsequently construction was started. Later on contracts with Chinese firm, M/s. CMEC, were signed for three units in two stages - Two Units each of 210 MW and one unit of 320 MW. In this way a power complex emerged which is going to be the biggest of all Thermal Stations in Pakistan with the possibility of construction of two more units. Presently, the total generation capability of three phases is envisaged as 1,370 MW.

2.3. Phase - 1 (Units 1, 2 & 3) This phase consists of three steam units each capable of generating 210 MW electricity. The supplier started delivery of equipment to site in January, 1989, and after pre-assembly of equipment at Site, erection started in July, 1990. Unit No. 1 was commissioned in September, 1993 and Unit No. 2 in March, 1994.

2.4. Main Building It contains the turbine hall having a span of 45 meters and deaerator bay, 12 meters wide. The steam turbines which drive generators are of three stages condensing type arranged transversely to the axis of turbine hall. The operational platform is at elevation 12.6 meters and a maintenance bay at ground floor near Unit No. 1. The power plant is designed on the block principle: boiler-turbinegenerator-unit transformer. The fuel gas exhaust section of two units is connected with a 200-meterhigh stack, outer section of which is a 195-meter high concrete shell.

2.5. Combined Auxiliary Building The building is connected with the main building and it houses water treatment plant to produce 100 t/h demineralized water for the replenishment of station losses, hydrogen plant to provide hydrogen for cooling of generators rotors, maintenance shops, laboratories and central control room.

Chapter 2-30 of 157

Chapter 2 GENCO Thermal Power Station 3

2.6. Fuel & Oil Facilities Fuel oil facilities are constructed for decanting, oil storage, preparation and supply of fuel to boiler nozzles. It also includes HSD storage as well as oil facilities for reception, storage, purification and centralized delivery of turbine oil and insulating oil to power plant.

2.7. Hydraulic Structures The cooling water used in condensers is re-circulated in closed cycle with inducted draft cooling towers. The water is being cooled for each unit in two cooling towers each consisting of eight fans. Two cooling towers carry 27,500 Cu m/h circulating water for condensers of one unit.

2.8. Startup Boiler One startup boiler using diesel oil as fuel with steam output of 50 t/h is provided to meet steam requirement for initial start of unit as well as a backup of power plant auxiliaries. A separate stack of 30-meter high has been constructed for it.

2.9. Electrical Section The electricity generated at 15.75 KV is brought out from Unit transformer at 220 KV and fed to the National Grid via a switchyard. Power Plant auxiliaries are fed at 6.6 KV.

2.10. Phase-II (Units 5 & 6) It consists of two units of 210 MW each having equipment similar to Phase-I. Turbines are placed longitudinally in main building. Outdoor boilers exhaust of two units is connected to one stack.

2.11. Overview There are many different types of power plants including thermal power plants and hydel power plants. Thermal power plants use fuel such as Gas, HSD, Furnace Oil or nuclear fuel to produce heat energy that is converted to electrical energy through a series of intermediate processes. Hydel power plants convert the potential energy of water to electrical power as it flows from higher to lower elevations. The "traditional" thermal power plant is the Rankine cycle plant, named after the man who invented the cycle. A power plant cycle is a series of processes in which a fluid, generally water/steam, is used to convert heat energy to mechanical energy. The Rankine cycle in its simplest form consists of a boiler, a turbine, a condenser, and a boiler feed pump. Early plants had thermal efficiencies of approximately 25% to 30%. Only 25% to 30% of the heat energy in the fuel burned in these plants was converted to electrical energy. The rest was lost in various ways. The Rankine cycle has been refined considerably over the years and made more efficient by the addition of components like Economizer, Feed water heaters, Super heaters and Reheaters. The

Chapter 2-31 of 157


efficiency of the Rankine cycle has also been improved by increasing the pressure and temperature of the cycle. The laws of thermodynamics and considerations such as material limitations have prevented any significant improvement since then. Power plants commonly use heat rate to measure efficiency.

Fuel Energy

Boiler

Heat Energy

Turbine

Mechanical Energy

Generator

Electrical Energy

Figure 2-1 Flow Diagram of Energy Conversion

2.12. Boiler The boiler is the main part of any thermal power plant. It converts the fuel energy into steam energy. The fuel may be furnace oil, diesel oil, natural gas or coal. The boilers may be fired from the multiple fuels. The type of boiler used in the TPS phase- II is “water tube type”.

2.13. Water Tube Type In watertube boilers, boiler water passes through the tubes while the exhaust gases remain in the shell side, passing over the tube surfaces. Since tubes can typically withstand higher internal pressure than the large chamber shell in a firetube, watertube boilers are used where high steam pressures (as high as 3,000 psi) are required. Watertube boilers are also capable of high efficiencies and can generate saturated or superheated steam. The ability of watertube boilers to generate superheated steam makes these boilers particularly attractive in applications that require dry, high pressure, high-energy steam, including steam turbine power generation.

2.14. Parameter of Boiler

Sr. No.

Parameter of Boiler

Units

680 /ℎ

1

Rated evaporating amount

2

Reheat steam amount

575.8 /ℎ

3

Main steam pressure

140 / 

4

Temperature

5

Outlet pressure of Reheat system

541° 23.8 / 

Chapter 2-32 of 157


541°

6

Outlet Temperature of Reheat System

7

Inlet pressure of Reheat System

8

Inlet Temperature of Reheat System

310°

9

Feed water Temperature

251°

10

Boiler Efficiency (burn oil)

90.26%

11

Boiler Efficiency (burn gas)

85%

12

Exit gas Temperature (burn oil)

153°

13

Exit gas Temperature (burn gas)

136°

14

Consumption of crude oil

15

Consumption of natural gas

25.8 / 

48.2 /ℎ 59650 /ℎ

Table 2-2

Chapter 2-33 of 157


Figure 2-2 Gate Type Furnace

Chapter 2-34 of 157


2.15. Main Parts of Boiler The boilers consist of the following main parts. 1. Forced Draft Fan (FDF) 2. Air Preheater (RAH) 3. Burners 4. Furnace 5. Up Rise Tubes 6. Down Comer Tubes 7. Water Tubes 8. Super Heaters 9. Gas Recirculation Fan (GRCF) 10. Re-Heater 11. Induced Draft Fan (IDF) 12. Chimney 13. Boiler Drum 14. Economizer

2.16. Forced Draft Fan The forced draft fan (FDF) sucks the air from the atmosphere which is used in the furnace for burning. The air from the atmosphere is passed through the filter to remove the dust and other particles from the air. The air from the FDF is then feeded feeded to the regenerative regenerative air heaters. The motor of the FDF has following specification Sr. No.

Parameter of Force Draft Fan

Units

1

Type

KK 800 11- 8

2

Rated Voltage

6.6KV

3

Rated Current

114 /121.3A

4

Rated Speed

747 RPM

5

Output

1000KW

6

Connection of Stator /Rotor

Y

7

Insulation Class

F

8

Permissible Rise

80K

Chapter 2-35 of 157


40°

9

Ambient Temperature

10

No. Of Phase

11

Rated Frequency

50Hz

12

Power Factor

0.81

13

Degree of Protection

IP54

14

Moment of Inertia

15

Weight

3

310.  13250Kg Table 2-3

2.17. Induced Draft Fan (IDF) ID fan sucks the flue gases from boiler and exhaust through chimney. The motor of the IDF has following specification. Sr. No.

Parameter of Induced Draft Fan

Units

1

Type

YKK 800 11- 6

2

Rated Voltage

6.6KV

3

Rated Current

20 A

4

Rated Speed

991 RPM

5

Output

2000KW

6


2Y

7

Insulation Class

F

8

Permissible Rise

80K

9

Ambient Temperature

40°

10

No. Of Phase

3

11

Rated Frequency

50Hz

12

Power Factor

0.81

13


IP54

14

Moment of Inertia

410.  Chapter 2-36 of 157


Weight

15

15970Kg Table 2-4

2.18. Gas Recirculation Fan (GRCF) The motor of the Gas Recirculation Fan (GRCF) has following specification. Sr. No.

Parameter of Gas Recirculation Fan

Units

1

Type

KK 400 11- 4

2

Rated Voltage

6.6KV

3

Rated Current

34 A

4

Rated Speed

1491 RPM

5

Rated Power

315 KW

6


Y

7

Insulation Class

F

8

Permissible Rise

70K

9

Ambient Temperature

50°

10

No. Of Phase

11

Rated Frequency

50Hz

12

Power Factor

0.81

13


IP54

14

Moment of Inertia

15

Weight

3

11.7. 11.7.   3200 Kg Table 2-5

2.19. Cooling Towers: Cooling towers are heat removal devices used to transfer process waste heat to the atmosphere. Cooling towers may either use the evaporation of water w ater to remove process heat and cool the working fluid to near the wet-bulb air temperature or rely solely on air t o cool the working fluid to near the dry-bulb air temperature. Common applications include cooling the circulating water used in oil refineries, chemical plants, power stations.

Chapter 2-37 of 157


2.20. Cooling Water Pump The motor of the CWP has following specification. Sr. No.

Parameter of Cooling Water Pump

Units

1

Type

Y1600-16/2150

2

Stator Voltage

6.6KV

3

Stator Current

182 A

4

Rated Speed

372 RPM

5

Output Power

1600 KW

6

Connection of Stator

7

Insulation Class

8

Ambient Temperature

9

No. Of Phase

10

Rated Frequency

50Hz

11

Power Factor

0.81

12

Weight

2Y B

50° 3

17500 Kg Table 2-6

2.21. Condensate Water Pump The Pump has following specification. Sr. No.

Parameter of Condensate Water Pump

Units

1

Type

1400S25-1

2

Capacity

1600  /ℎ

3

Rated Speed

370 RPM

4

Rated Power

1600 KW

5

Head

6

Weight

25 m 35000 Kg Table 2-7

Chapter 2-38 of 157


2.22. Air Preheater An air preheater or air heater is a general term to describe any device designed to heat air before another process (for example, combustion in a boiler) with the primary objective of increasing the thermal efficiency of the process. They may be used alone or to replace a r ecuperative heat system or to replace a steam coil. The purpose of the air preheater is to recover the heat from the boiler flue gas which increases the thermal efficiency of the boiler by reducing the useful heat lost in the flue gas. As a consequence, the flue gases are also sent to the flue gas stack (or chimney) at a lower temperature, allowing simplified design of the ducting and the flue gas stack. It also allows control over the temperature of gases leaving the stack.

Figure 2-3 Regenerative Air PreHeater

2.23. Economizers Flue gases from large boilers are typically 450 - 650°F. Stack Economizers recover some of this heat for pre-heating water. The water is most often used for boiler make-up water or some other need that coincides with boiler operation. Stack Economizers should be considered as an efficiency measure when large amounts of make-up water are used (i.e. not all condensate is returned to the boiler or large amounts of live steam are used in the process so there is no condensate to return) or there is a simultaneous need for large quantities of hot water for some other use. The savings potential is based on the existing stack temperature, the volume of makeup water needed, and the hours of operation. Economizers are available in a wide range of sizes, from small coil-like units to very large waste heat recovery boilers. The savings potential is a function of how much heat can be recovered, which is a function of how much cold water needs to be heated. A generally accepted "rule of thumb" is that about 5% of boiler input capacity can be recovered with a properly sized economizer. A higher percentage can be recovered with a Flue Gas Condenser, assuming there is enough cold water to condense all of the flue gas that is available. Therefore, for 'ball parking'

Chapter 2-39 of 157


purposes, start by comparing boiler input capacity with the need to heat water. An economizer that recovers 5% of boiler input should easily have a 2-years payback in a year-round application.

2.24. Boiler Protection 1. Fuel protection 2. Gas pressure protection 3. Diesel oil protection 4. Furnace oil protection 5. FD fan trip 6. ID fan trip 7. Regenerative air pre heater trip 8. Drum level high 9. Drum low level 10. Reheat steam pressure drop 11. Furnace pressure low 12. Furnace flame out 13. Natural gas pressure high

Chapter 2-40 of 157


2.25. Thermal Power Cycle

Boiler Drum

HP Cylinder

Re-Heater

IP Cylinder

LP Cylinder

Condenser

Hot Well

Condensate Pump

Air Ejector

Vent Steam Condenser

LP Heater 1 Stage 1

Gland Steam Condenser

LP Heater Stage 2

LP Heater 2,3,4

Deaerator Tank

Feed Tank

Feed Water Pump 1,2,3

HP Heaters 5,6,7

Economizer

Boiler Drum

Figure 2-4 Thermal Cycle

Chapter 2-41 of 157

Chapter

3 3. Introduction

A steam Turbine is a device that extracts Thermal Energy from Pressurized steam and uses it to do Mechanical Energy OR Steam Turbine is a device where Kinetic Energy converted into Mechanical Energy. Turbine used in Thermal Power Station Muzaffargarh is impulse-reaction

steam turbine. The load requirement is controlled by the steam flow through a governing valve. Maximum steam flow at full load is 670 tons/hour. When the load at the generator is suddenly decreased then the rpm (frequency) of the generator is increased and to decrease the frequency we lower down the steam flow which decreases the speed and maintains the frequency. If load is suddenly increased rotor speed becomes slower, to increase the speed, steam flow is increased.

3.1. Rating & Design Data OEM: Power Machines OJSC (Russia) Model: k-210-130-8

3 Cylinder Tandem Compound Multistage Steam turbine (HP-IP-LP) Condensing Turbine Rated Power: 210MW RPM: 3000 Dimensions: 19 x 6.5 x 5.5 (L×W×H) in meters Inlet Temp: 540˚C Inlet Pressure: 130

⁄ 

Exhaust Pressure: Nearly 1

⁄ 

•

Dual flow steam turbine

•

IP and LP turbines are Dual Reverse flow steam turbine

Page 3-42 of 157

Chapter 3 Steam Turbines •

•

Number of Extractions are 7 Total stages 29 1. HP Turbine = 12 stages 2. IP Turbine = 11 stages 3. LP Turbine = 06 stages

3.2. Description of Steam Cycle Steam from the boiler after passes through the super heaters enter into steam main and then passes through the following equipment’s. 1. Steam from the steam main at 540 ℃ & 130kg/cm 2 entre into the governing system of the

H.P turbine and then to H.P turbine. 2. Firstly, steam strikes to the cultus wheel and then passes through the fixed and the moving

blades of all other stages. 3. Steam at 130kg/cm 2 and 540 ℃ entre into H.P turbine and leaves at 27.5kg/cm 2 and 330℃. 4. Then this steam goes to the reheaters for reheat and finally it entre into the I.P turbine at

25.5kg/cm2 and 540 ℃. 5. After I.P steam goes to L.P turbine through cross over pipe. 6. Finally, after the energy conversion steam entre into the condenser for the changing its 2

phase from gaseous to liquid.

Figure 3-1 Steam Cycle

Chapter 3-43 of 157

Chapter 3 Steam Turbines

3.3. Process Diagram of Turbine Steam Cycle

Figure 3-2 Turbine Steam Cycle

Chapter 3-44 of 157


Figure 3-3 Steam Turbine Cross-Section View

Chapter 3-45 of 157


Figure 3-4 Steam flow

3.4. Classification of Steam Turbines In order to better understand turbine operation, Four Basic Classifications are discussed. Type of Steam Flow & Division of Steam Flow , describes the flow of steam in relation to the axis of the

rotor. Indicates whether the steam flows in just one direction or if it flows in more than one direction. Way of Energy Conversion & Type of Blading , Reaction, Impulse and Impulse & Reaction Combine. identifies the blading as either impulse blading or reaction blading. Type of Compounding & Cylinder arrangement refers to the use of blading which causes a series of

pressure drops, a series of velocity drops, or a combination of the two. (number of cylinders; whether single, tandem or cross-compound in design). Exhausting Condition & Number of Stages

Chapter 3-46 of 157


is determined by whether the turbine exhausts into its own condenser or whether it exhausts into another piping system.

3.5. Type of Steam Flow Turbines may be classified according to the direction of steam flow in r elation to the turbine wheel or drum. 1. Axial 2. Radial 3. Mixed Tangential or Helical

Figure 3-5 Type of Steam Flow

3.6. Axial Flow The great majority of turbines, especially those of high power, are axial flow. In such turbines the steam flows in a direction or directions parallel to the axis of the wheel or rotor. The axial flow type of turbine is the most preferred for electricity generation as several cylinders can be easily coupled together to achieve a turbine with a greater output.

3.7. Reverse Flow In some modern turbine designs the steam flows through part of the high pressure (HP) cylinder and then is reversed to flow in the opposite direction through the remainder of the HP cylinder. The benefits of this arrangement are: outer casing joint flanges and bolts experience much lower steam conditions than with the one direction design reduction or elimination of axial (parallel to shaft)

Figure 3-6. Reverse Flow

thrust created within the cylinder lower steam pressure that the outer casing shaft glands have to accommodate.

Chapter 3-47 of 157


3.8. Way of Energy Conversion & Types of Blading The heat energy contained within the steam that passes through a turbine must be converted into mechanical energy. How this is achieved depends on the shape of the turbine blades. The two basic blade designs are 1. Impulse Turbines 2. Reaction Turbines

** Impulse & Reaction Combine

3.9. Impulse Blades Impulse blades work on the principle of high pressure steam striking or hitting against the moving blades. Impulse blades are usually symmetrical and have an entrance and exit angle of approximately 20 °. They are generally installed in the higher pressure sections of the turbine where the specific volume of steam is low and requires much smaller flow areas than that at lower pressures. The impulse blades are short and have a constant cross section. Figure 3-7 Impulse Blades

3.10. Reaction Blades The principle of a pure reaction turbine is that all the energy contained within the steam is converted to mechanical energy by reaction of the jet of steam as it expands through the blades of the rotor. A simple reaction turbine is shown in Figure 19. The rotor is forced to rotate as the expanding steam exhausts the rotor arm nozzles. In a reaction turbine the steam expands when passing across the fixed blades and incurs a pressure drop and an increase in velocity. When passing across the moving blades the steam incurs both a pressure drop and a decrease in velocity.

3.11. Impulse Stage

Figure 3-8 Reaction Blades

In Impulse Stage Whole pressure drop in nozzle (whole enthalpy drop is changed into kinetic energy in the nozzle). Impulse Stage an impulse stage consists of stationary blades forming nozzles through which the steam expands, increasing velocity as a result of decreasing pressure. The steam then strikes the rotating blades and performs work on them, which in turn decreases the velocity (kinetic energy) of the steam. The stream then passes through another set of stationary blades which turn it back to the original direction and increases the velocity again though nozzle action.

Chapter 3-48 of 157


Figure 3-9 Impulse Stage

3.12. Reaction Stage In Reaction Stage Pressure drop both in stationary blades and in rotary blades (enthalpy drop changed into kinetic energy both in stationary blades and in the moving blades in rotor). Reaction Turbine both the moving blades and the non-moving blades designed to act like nozzles. As steam passes through the non-moving blades, no work is extracted. Pressure will decrease and velocity will increase as steam passes through these non-moving blades. In the moving blades work is extracted. Even though the moving blades are designed to act like nozzles, velocity and pressure will decrease due to work being extracted from the steam.

Figure 3-10 Reaction Stage

Chapter 3-49 of 157


Figure 3-11 Impulse & Reaction Turbine

3.13. Way of Compounding 3.14. Compounding of Impulse Turbine This is done to reduce the rotational speed of the impulse turbine to practical limits. (A rotor speed of 30,000 rpm is possible, which is pretty high for practical uses.) Compounding is achieved by using more than one set of nozzles, blades, rotors, in a series, keyed to a common shaft; so that either the steam pressure or the jet velocity is absorbed by the turbine in stages. Three main types of compounded impulse turbines are. 1. Pressure compounded 2. velocity compounded 3. pressure and velocity compounded impulse turbines

3.15. Pressure Compounding Impulse Turbine With pressure compounding the total steam pressure to exhaust pressure is broken into several pressure drops through a series of sets of nozzles and blades. Each set of one row of nozzles and one row of moving blades is referred to as a stage. This involves splitting up of the whole pressure

drop from the steam chest pressure to the condenser pressure into a series of smaller pressure drops across several stages of impulse turbine. The nozzles are fitted into a diaphragm locked in the casing. This diaphragm separates one-wheel chamber from another. All rotors are mounted on the same shaft and the blades are attached on the rotor. Pressure staging is also known as RATEAU staging.

Chapter 3-50 of 157


Figure 3-12 Pressure Compounding Impulse Turbine

3.16. Velocity Compounded Impulse Turbine Velocity Compounded Impulse Turbine When the velocity energy produced by one set of fixed nozzles is unable to be efficiently converted into rotational motion by one set of moving blades then it is common to install a series of blades as shown in Figure 24. This arrangement is known as velocity compounding.

Velocity drop is arranged in many small drops through many moving

rows of blades instead of a single row of moving blades. It consists of a nozzle or a set of nozzles and rows of moving blades attached to the rotor or the wheel and rows of fixed blades attached to the casing.

Figure 3-13 Velocity Compounded Impulse Turbine

3.17. Pressure-Velocity Compounded Impulse Turbine This is a combination of pressure-velocity compounding. Most modern turbines have a combination of pressure and velocity compounding. This type of arrangement provides a smaller, shorter and

Chapter 3-51 of 157


cheaper turbine; but has a slight efficiency trade off. Turbines using this arrangement are often referred to as CURTIS turbines after the inventor. Individual pressure stages (each with two or more velocity stages) are sometimes called CURTIS stages.

Figure 3-14 Pressure-velocity Compounded Impulse Turbine

3.18. Curtis Stage This setup of a nozzle followed by a set of moving blades, non-moving blades, and moving blades makes up a single Curtis stage. After steam exits the nozzle there are no further pressure drops. However, across both sets of moving blades there is a velocity drop. This causes the Curtis stage to be classified as velocity compounded blading.

Figure 3-15 Curtis stage

3.19. Cylinder arrangement Turbines can be arranged either single cylinder or multi-stage in design. The multi-stage can be either velocity, pressure or velocity-pressure compounded (discussed as earlier).

Chapter 3-52 of 157


3.20. Single cylinder construction or Single Flow Turbine. Single cylinder turbines have only one-cylinder casing (although may be is multiple sections). Steam enters at the high pressure section of the turbine and passes through the turbine to the low pressure end of the turbine then exhausts to the condenser.

Figure 3-16 Single cylinder turbines

3.21. Tandem construction or Compound Flow Turbine Modern turbines are manufactured in multiple sections also called cylinders. Greater output and efficiency can be achieved by coupling a number of individual cylinders together in what is referred to as tandem (on one axis). Tandem compound Large electric power generating turbines commonly have a high pressure casing, which receives superheated steam directly from the boiler or steam generator. The high pressure turbine may then exhaust to an intermediate pressure turbine, or may pass back to a reheat section in the boiler before passing to a reheat intermediate pressure turbine. The reheat turbine may then exhaust to one or more low pressure casings, which are usually two exhaust flow turbines, with the low pressure steam entering the middle of the turbine and flowing in opposite directions toward two exhaust end before passing into the condenser. When the turbine casings are arranged on a single shaft, the turbine is said to be tandem compounded.

3.22. Cylinder Arrangement Tandem construction Three Cylinder Turbine It has a double flow LP cylinder with an IP cylinder arranged so that the steam flow through it is in the opposite direction to the HP cylinder. This design also greatly reduces the axial thrust on the rotor.

Chapter 3-53 of 157


Figure 3-17 Three Cylinder Turbine

3.23. Tandem Cross-Compounding Turbine In cross compound turbines, the high-pressure, exhaust passes over to intermediate or low pressure casings which are mounted on separate shafts. The two shafts may drive separate loads, or may be geared together to a single load. In some larger overseas installations that operate at 60 hertz (frequency) the use of cross-compounding is sometimes employed. Cross-compounding is where the HP and IP cylinders are mounted on one shaft driving one alternator while the LP cylinders are mounted on a separate shaft driving another alternator. This is done so as the LP cylinder with its large diameter blading can be operated at a greatly reduced speed thus reducing the centrifugal force.

Figure 3-18 cross compound turbines

3.24. Number of Stages 1. Single stage 2. Multi-stage

Chapter 3-54 of 157

Chapter 3 Steam Turbines The stage is a set of moving blades behind the nozzle. In a reaction turbine, each row of blades is called a "stage." A single Curtis stage stage may consist of two or more rows of moving blades.

3.25. Exhaust Conditions 1. Condensing 2. Extraction 3. Back-pressure

Figure 3-19 Exhaust Conditions

3.26. Condensing The condensing turbine processes result in maximum power and electrical generation efficiency from the steam supply and boiler fuel. The power output of condensing turbines is sensitive to ambient conditions. The cooling water condenses the steam turbine exhaust steam in the condenser creating the condenser vacuum. As a small amount of air leaks into the system when it is below atmospheric pressure, a relatively small compressor (Vacuum pump) or Air Ejector System removes non-condensable non-condensable gases from the condenser.

3.27. Extraction In an extraction turbine, steam is withdrawn from one or more stages, at one or more pressures, for heating, plant process, or feed water heater needs. They are often called " bleeder turbines “. The steam extraction pressure may or may not be automatically regulated. Regulated extraction extraction permits more steam to flow through the turbine to generate additional electricity during periods of low thermal demand by the CHP (Combined Heat Power) system. In utility type steam turbines, there may be several extraction points, each at a different pressure corresponding to a different temperature. The facility’s specific needs for steam and power over time determine the extent to

which steam in an extraction turbine is extracted for use in the process.

3.28. Back-Pressure The non-condensing turbine (also referred to as a back-pressure turbine) exhausts its entire flow of of steam to the industrial process or facility steam mains at conditions close to the process heat requirements.

Chapter 3-55 of 157


Where the steam of vent steam condenser and gland steam condenser comes from?

Steam for the vent & gland steam condenser comes from the venting steam of auxiliaries and from the gland packing of valves also the sealing steam of the turbine and the valves r espectively. They are U-shaped shell & tube heat exchanger in which steam is in the shell and tubes contains the feed water for utilizing their energy. Where the steam of H.P & L.P heater come from?

Steam for the H.P & L.P heater are the bleeding steam of different stages of the turbine. this steam could be extracts from the turbine for three purposes, 

To avoid in the leakages of expanded steam from turbine body.



To reduce the pressure of the steam in order to make it useful for next stages.



To avoid thermal stresses developed in the turbine body.

3.29. Detailed view of the steam extraction Total Extractions = 7 High Pressure Pressure Heaters = 3 Low Pressure Pressure Heaters = 4

First extraction is done done at 9 th stage of High Hi gh Pressure turbine, Pressure turbine,

Extraction No.

H.P Extraction 01 H.P Extraction 02 I.P Extraction 03 I.P Extraction 04 I.P Extraction 05 I.P Extraction 06

Pressure

Temperature

Kg/cm2

℃

Flow of Steam t/hr.

7

41.2

381

32.9

6

28.1

332

45.3

5

12.8

448

19.5

4

6.8

359

25.3

3

2.9

255

20.6

2

1.26

168

25.3

Heater No.

Chapter 3-56 of 157


L.P Extraction 07

1

0.28

67

12.3

Table 3-1

For 210MW generation 640t/hr. flow of steam is required, if the unit is running at its full load capacity then, 

Total Steam from boiler = 640t/hr.



Total extraction = 181.2 t/hr.



Steam to condenser = 458.8 t/hr.

3.30. Turbine Losses In actual practice, not all of the energy in the steam is converted to useful work. Losses common to all turbines are described below. Loss of Working Working Substance Loss of steam along the shaft through the shaft glands where the shaft

penetrates the casing. Work loss. Loss due to mechanical friction between moving parts. Throttling loss. Wherever there is a reduction in steam pressure without a corresponding production of work,

such as in a throttle valve. Leaving loss. The kinetic energy of the steam leaving the last stage blading. This leaving loss can be minimized minimized by lightly loading the last stage blading by increasing the annular exhaust area of the turbine. This is often oft en optimized through economic studies. Windage loss. This is caused by fluid friction as the turbine wheel and blades rotate through the surrounding

steam. Friction loss as the steam passes through nozzles and blading. Diaphragm packing loss as the steam passes from one stage to another through the diaphragm packing. Tip leakage loss in reaction turbines as steam passes over the tips of the blades without doing any useful work.

3.31. Rankine Cycle Rankine cycle with superheat Process 1-2: The working fluid is pumped from low to high pressure. Process 2-3: The high pressure liquid enters a boiler where it is heated at constant pressure by an

external heat source to become a dry saturated vapor. Process 3-3': The vapors are superheated. Process 3-4 and 3'-4': The dry saturated s aturated vapor expands through a turbine, generating power. This

decreases the temperature and pressure of the vapor, and some s ome condensation may occur. Process 41: The wet vapor then enters a condenser where it is condensed at a constant pressure to become a

saturated liquid.

Chapter 3-57 of 157


Figure 3-20 TS Diagram for Rankine Cycle

3.32. Steam Turbine Components and Relative Equipment’s 1. Foundation 2. Rotor or Shaft 3. Cylinder or Casing 4. Blades 5. Diaphragm 6. Steam Chest 7. Coupling 8. Bearings 9. Labyrinth Seal 10. Front Pedestal 11. TSI (Turbine Supervisory Instrumentation) 12. D-EHC (Governor) Digital Electro Hydraulic Control System 13. MSV (Main Steam Stop Valve) 14. CV (Control Valve) 15. IV (Intercept Valve) 16. CRV (Combined Reheat Valve) 17. Turbine Turning Gear 18. Turbine Bypass & Drains 19. Atmospheric Relief Diaphragm (Rupture Disk) 20. Lube Oil System 21. EHC Oil System (Electro Hydraulic Controlled) 22. Gland Steam System 23. Condenser

Chapter 3-58 of 157

Chapter 3 Steam Turbines 24. Steam Jet Ejector 25. Vacuum Breaker

Figure 3-21 Steam Turbine Components Frame (Base): supports the stator, rotor and governor pedestal. Shell: Consists cylinder, casing, nozzles, steam chest & bearing. Rotor: Consists of low, intermediate, and high pressure stage blades, and possible stub shaft (s) for

governor pedestal components, thrust bearing, journal bearings, turning gear & main lube oil system. Governor Pedestal: Consists of the EHC oil system, turbine speed governor, and protective

devices. Steam Turbine Rotor: Steam Turbine Rotor a multistage steam turbines are manufactured with

solid forged rotor construction. Rotors are precisely machined from solid alloy steel forgings. An integrally forged rotor provides increased reliability particularly for high speed applications. The complete rotor assembly is dynamically balanced at operating speed and over speed tested in a vacuum bunker to ensure safety in operation. High speed balancing can also reduce residual stresses and the effects of blade seating.

Chapter 3-59 of 157


Turbine Casing: The casings of turbine cylinders are of simple construction to minimize any

distortion due to temperature changes. They are constructed in two halves (top and bottom) along a horizontal joint so that the cylinder is easily opened for inspection and maintenance. With the top cylinder casing removed the rotor can also be easily withdrawn without interfering with the alignment of the bearings. Most turbines constructed today either have a double or partial double casing on the high pressure (HP) and intermediate pressure (IP) cylinders. This arrangement subjects the outer casing joint flanges, bolts and outer casing glands to lower steam condition. This also makes it possible for reverse flow within the cylinder and greatly reduces fabrication thickness as pressure within the cylinder is distributed across two casings instead of one. This reduced wall thickness also enables the cylinder to respond more rapidly to changes in steam temperature due to the reduced thermal mass. The high-pressure end of the turbine is supported by the steam end bearing housing which is flexibly mounted to allow for axial expansion caused by temperature changes. The exhaust casing is centerline supported on pedestals that maintain perfect unit alignment while permitting lateral expansion. Covers on both the steam end and exhaust end bearing housings and seal housings may be lifted independently of the main casing to provide ready access to such items as the bearings, control components and seals.

Figure 3-22 The casings of turbine

Chapter 3-60 of 157


Figure 3-23 The casings of turbine Steam Turbine Blades: Blade design is extremely important in attaining high turbine reliability

and efficiency. A large selection of efficient blade profiles has been developed and proven by extensive field service allowing for optimal blade selection for all conditions of s ervice. Blades are milled from stainless steel within strict specifications for proper strength, damping and corrosion resistant properties. Disk profiles are designed to minimize centrifugal stresses, thermal gradient and blade loading at the disk rims.

Figure 3-24 Steam Turbine Blades Stationary Blade or Diaphragm: Stationary Blade or Diaphragm Partitions between pressure

stages in a turbine's casing are called diaphragms. They hold the vane-shaped nozzles and seals between the stages. Usually labyrinth-type seals are used. One-half of the diaphragm is fitted into the top of the casing, the other half into the bottom. Nozzle rings and diaphragms are specifically designed and fabricated to handle the pressure, temperature and volume of the steam, the size of the turbine and the required pressure drop across the stage. The nozzles used in the first stage nozzle ring are cut from stainless steel. Steam passages are then precision milled into these nozzle blocks before they are welded together to form the nozzle ring.

Chapter 3-61 of 157


Figure 3-25 Stationary Blade or Diaphragm

The nozzles in the intermediate pressure stages are formed from profiled stainless steel nozzle sections and inner and outer bands. These are then welded to a circular center section and to an outer ring then precision machined. The low-pressure diaphragms in condensing turbines are made by casting the stainless nozzle sections directly into high-strength cast iron. This design includes a moisture catching provision around the circumference which collects released moisture and removes it from the steam passage. Additional features such as windage shields and inter-stage drains are used as required by stage conditions to minimize erosion. All diaphragms are horizontally split for easy removal and alignment adjustment. Turbine Blade Fixing: Various root fixing shapes have been developed for turbine blading to suit

both construction requirements and conditions under which turbines operate. The most popular types of blade root fixing available are. 1. Grooves 2. Straddle 3. Rivet

Chapter 3-62 of 157


Figure 3-26 Various root fixing shapes Steam Chest: The steam chest, located on the forward, upper half of the HP turbine casing, houses

the throttle valve assembly. This is the area of the turbine where main steam first enters the main engine. The throttle valve assembly regulates the amount of steam entering the turbine. After passing through the throttle valve, steam enters the nozzle block. Coupling: Coupling with multi-cylinder turbines it is necessary to have some method of connecting

individual cylinder rotors. It is also a requirement to connect the turbine to the alternator rotor. To achieve these connections, we use a device known as a coupling. These couplings must be capable of transmitting heavy loads and in some turbines are required to accommodate for axial expansion and contraction. The types of couplings generally employed in power plants are: 1. Flexible coupling 2. Solid shaft coupling Journal Bearing: The turbine rotors are supported by two journal bearings. Both the No.1 and

No.2 bearings are of a double-tilting pad type. The bearing metal is divided into six pads which are self-aligned. A center adjustment of these bearings can easily be made with shimmed pads. Double Tilting Pad Type Journal Bearing: Double tilting pad bearing provides maximum

stability and freedom from shaft vibration. The tilting-pad design consists generally of six steel pads (shoes) with Babbitt linings on the bearing surface. The pads are installed on the inner of bearing ring, and can move radial and axial direction. Therefore, the pads Move smoothly, and maintain the correct alignment at all conditions. Hook fits in the inner of bearing ring retain the pads, and the pads are prevented from rotating by means of loose-fitting lock pins.

Chapter 3-63 of 157

Chapter 3 Steam Turbines Tapered-Land Thrust Bearing: The thrust bearing is located on the main shaft of the turbine.

Independently mounted inside the standard, the thrust bearing absorbs the axial thrust of the turbine and generator rotors, which are connected by a solid coupling. This tapered-land thrust bearing consists of two stationary thrust plates and two rotating Thrust collars on the turbine shaft which will provide the front and back faces to the bearing. These plates are supported in a casing so that they may be positioned against the rotating faces of the collars. The thrust collar faces are machined and lapped, producing smooth, parallel surfaces. Labyrinth Seal A labyrinth seal is a type of mechanical seal that provides a tortuous path to help

prevent leakage. An example of such a seal is sometimes found within an axle 's bearing to help prevent the leakage of the oil lubricating the bearing. A labyrinth seal may be composed of many grooves that press tightly inside another axle, or inside a hole, so that the fluid has to pass through a long and difficult path to escape.

Figure 3-27 labyrinth seal

Labyrinth seals are utilized as end gland seals and also inter-stage seals. Stationary labyrinth seals are standard for all multistage turbines and grooves are machined on the rotating part to improve the sealing effect. The leakage steam from the outer glands is generally condensed by the gland condenser. Some leakage steam from the intermediate section of the steam end gland seals can be withdrawn and utilized by re-injecting it into the low-pressure stage or low- pressure steam line. Front Standard & TSI : Supports the No.1 bearing, thrust bearing and the front end of the turbine

casing. Front standard is shaped like a box. Upper half of the standard can be disassembled at horizontal flange. A manhole located front of upper half is used oil strainer maintenance. This box is not only the bearing standard but control box which contains some important equipment. There are some instruments and button on the outside of the front pedestal cover. These are used for turbine operation and supervision. Some protective devices and speed detectors are installed inside the standard. Inside space of the standard is connected to oil tank and is kept slightly vacuum so that the oil drain or mist inside cannot leak out. Lubricating oil is supplied from oil pipe which

Chapter 3-64 of 157


is located left side of front standard and flow out to oil tank through 1 st journal and thrust bearings. Oil strainer is located up stream of bearing. Toothed-wheel for speed sensors The turbine rotating speed is sensed by the magnetic pickups faced to the toothed-wheel installed on the control rotor. The pulse signal is produced when each tooth passes the pickups. The frequency signals from two (2) pickups are converted into digital value proportional to the turbine speed through F/D (Frequency to Digital) converters. Other three (3) sensors are located around toothed-wheel. These sensors are used for tri p detector.

3.33. Turbine Supervisory Instrumentation (TSI) Turbine Supervisory Instrumentation (TSI) or Turbine Supervision Equipment (TSE) is a generic term used in the power generation industry. TSI refers to instrumentation systems that specifically perform measurements of critical control parameters on large steam turbine generator trains. The size of the machines can range between 50 – 1200 MW and their age can often be in excess of 30 years. TSI systems are normally a mandatory requirement. The same technology is employed on other turbine types and in other industries, such as the hydrocarbon-processing sector.

Figure 3-28 Turbine Supervisory Instrumentation

Turbine Supervisory Instrumentation (TSI) Although the turbine is not readily accessible during operation, the turbine supervisory instrumentation is sufficient to detect any potential malfunction. The turbine supervisory instrumentation includes monitoring of the following: 1. Vibration and eccentricity 2. Thrust bearing wear 3. Exhaust hood temperature and spray pressure 4. Oil system pressures, levels, and temperatures 5. Bearing metal and oil drain temperatures 6. Shell temperature 7. Valve positions 8. Shell and rotor differential expansion 9. Shaft speed, electrical load, and control valve inlet pressure indication

Chapter 3-65 of 157

Chapter 3 Steam Turbines 10. Hydrogen temperature, pressure, and purity 11. Stator coolant temperature and conductivity 12. Stator-winding temperature 13. Collector air temperatures 14. Turbine gland sealing pressure 15. Gland steam condenser vacuum 16. Steam chest pressure 17. Seal oil pressure Steam

3.34. TSI Benefits The use of, and experience with, TSI assists in reducing operating costs of the generation units by: Reducing Turbine Roll Time: During the run-up and coast-down of large turbines, there are

extensive soak periods to ensure stationary and rotating parts thermally expand equally. These periods are usually of a conservative length, but times can be further reduced with continuous and accurate measurement of key expansion clearances (and related parameters) available with TSI systems. Time Between Overhauls: By using precise TSI measurement information, in an outage, the exact

amount of work can be scheduled with reduced risk of unknown problems occurring after the overhaul is completed. Diagnostic and Troubleshooting: The trending of TSI data provides the user with the machine’s

basic operating characteristics. Early detection of changes in trended data and comparison to normal conditions allows decisions to be made more quickly and inexpensively. More advanced analysis methods of this same raw data can diagnose problems like mass unbalance, misalignment, lose or broken parts, shaft cracks, seal rubs, and bearing instabilities caused by improper lubrication or bearing design. Early identification of these problems allows for corrections to be made at a time that is convenient to both the work force and system load. Automatic Shutdown: Sometimes unanticipated problems arise quickly, however, TSI has the

capability to limit damage to the machine and protect against total destruction or catastrophic failure. Confining damage flagged by vibration can make the difference between a two-week outage and three to six months of down time. TSI system measurements can be broken down into four major categories: Motion Measurements Eddy current (proximity) probes, case mounted velocity (seismic)

transducers, shaft riders, and/or accelerometers can be used to monitor vibrations. Monitoring

Chapter 3-66 of 157


points may include vibration on main turbine generator and exciter, may also be used to measure rotor eccentricity. Position Measurements: Eddy current probes, LVDTs and linear/rotary potentiometers can be

used to monitor thrust bearing wear, rotor position, casing (shell) expansion, differential expansion and control valve position. Speed Measurements Active or passive electromagnetic or eddy current probes can be used to monitor main turbine speed and acceleration, over-speed detection, zero speed detection. Process Measurements Thermocouples or RTDs can be used to monitor bearing white metal temperature, shell differential temperature, and lube oil temperature. Piezoelectric or strain gauge pressure transducers can be used to measure oil and hydraulic

pressures. Arrangement of Shell Thermocouples: Thermocouples for water Induction When water flows

into the turbine due to an unexpected accident, there occurs a difference in temperature between the upper half and the lower half of the casing. As a result, (humped effect) phenomenon is generated on the casing, giving great damages to HP and IP casings, rotor blade, and thrust bearing. To detect any flow of water, therefore, thermocouples are provided at several positions of the upper and lower parts of the casing respectively to watch the difference in temperature between the upper and lower parts of the casing. Thermocouples for Measuring Temperatures of Internal and External Surfaces of Casing:

Thermocouples for Measuring Temperatures of Internal and External Surfaces of Casing At the time of cold starting of the turbine, there occurs a difference in temperature between the internal and external surfaces of casing with subsequent generation of thermal stress, which shortens the lives of turbine parts, To control the lives of turbine parts, a thermocouple is provided at each part of the casing for the purpose of carrying out life control for the parts.

3.35. Principles of Governing During operation of a Turbine Generator Unit the Load carried by the Generator may vary over time. In order to respond to changing System Load demands the amount of steam directed to the Turbine must be varied in proportion to each demand. The function of a governor is to provide rapid automatic response to load variations.

3.36. Steam Turbine Speed Control The Speeder Gear of a Turbine Governor in order to maintain the system frequency constant and at the same time allow load variation to occur, it is necessary to be able to compensate for the loss of speed experienced with increasing load and the speed increase which accompanies load rejection. To achieve this a device is fitted in conjunction with the governor which effectively changes the

Chapter 3-67 of 157


speed-load characteristic of the turbine in such a way that speed effectively becomes independent of load. The device is known as the speeder gear. Relays in all but the smallest turbine, it is necessary to use some means of amplifying the power of the governor in order to maintain a small sensing and control device and yet still have the motive force to position large sized throttle valves. The devices used as amplifiers are known as relays. The most common type of relay uses an oil system employing valve and a power piston. There are two types of these relays in use: Double acting and Single acting.

3.37. D-EHC (Digital Electro-Hydraulic Control System) D-EHC system can be applied to control, protection and monitoring of steam turbines for various type of power plants including conventional fossil-fired power plants, combined cycle plants, cogeneration plants, and atomic power plants. Powerful and reliable controllers: High-speed control with state-of-the-art microprocessor based

control system. Distributed and hierarchical architecture consists of: System controller, Master controller,

Programmable logic device, Valve interface. Normal Operation: During Normal Operation, the main stop valves, intermediate stop valves and

intercept valves are wide open. Operation of the T-G is under the control of the Electro-Hydraulic Control (EHC) System. The EHC System is comprised of three basic subsystems: the speed control unit, the load control unit, and the flow control unit. The normal function of the EHC System is to generate the position signals for the four main stop valves, four main control valves, and intermediate stop valves and intercept valves

3.38. Main Steam Stop Valve The main stop valve is located in the main steam piping between the boiler and the outlet piping to turbine control valve chest in turbine casing. The main stop valve has one inlet and two identical outlet pipe connections. Outlet pipes are welded directory. The primary function of the main stop valves is to quickly shut off the steam flow to the turbine under emergency conditions such as failure of the control valves to close on loss of load.

Chapter 3-68 of 157


Figure 3-29 main stop valve

3.39. Control Valves (Cv) The control valves are arranged into an upper and lower valve group with each group mounted on common chest which is an integral part of the upper and lower turbine outer shells. Each control valve admits steam from the valve chest of its group to an individual nozzle box, after that controlled steam flow into a particular section of the turbine first stage nozzles.

Figure 3-30 The control valves

3.40. Intercept Valves During starting and loading operation without turbine bypass system the intercept valves are operated fully opened for full arc admission starting. They remain fully open during transfer of steam flow control to the control valves, as well as all other periods of normal operation. The other

Chapter 3-69 of 157


side, when turbine bypass system is available for the starting up and loading. The intercept valves are used to control the steam flow to the intermediate turbine in conjunction with the control valves. After the turbine bypass operation is finished the intercept valves will be fully opened by EHC control system. The primary function of the intercept valve is pre-emergency protection: however, however, they also trip closed upon actuation of the emergency trip system. The secondary one is to control the steam flow during the starting st arting and loading with turbine bypass system. The reheat stop valve is provided to quickly shut off the steam flow storage in the reheated line to the turbine under emergency condition.

3.41. Combined Reheat Valves (CRV) Two combined reheat valves are provided, one in each hot reheat line. Supplying reheat steam to the turbine. As the name implies. The combined valve is actually two valve. The intercept valve and the reheat stop valve, incorporated in one valve casing. Although they utilize a common valve casing, these valves provide entirely different functions.

Figure 3-31 combined reheat valves

3.42. Turbine Turning Gear The motor driven turning gear is mounted on the turbine bearing cap, adjacent to the turbinegenerator coupling so as to mesh with a bull gear (spacer disk gear type). Which is i s bolted between the turbine-generator coupling faces. The primary function of the turning gear is to rotate the turbine-generator shaft slowly and continuously during shutdown periods when rotor temperature changes occur. When the turbine is shutdown, cooling of its inner elements is continues for many hours. If the rotor is allowed to remain stationary during this cooling period, distortion begins almost immediately. This distortion is caused by the flow of hot vapors to the upper part of the turbine casing, resulting in the upper half of the turbine being at a higher temperature than the lower

Chapter 3-70 of 157


half. The parts do not return to their normal position until the turbine has cooled to the point where both the upper and and lower halves are at at approximately the same temperature.

Figure 3-32 motor driven turning gear

3.43. Water induction Water induction can happen at any time; however, the most common situations are during transients such as startup, shut down and load changes. It is interesting that only 18 percent of water induction incidents occur when the unit is at load. Turbine drains are necessary to avoid slugging nozzles and blades inside the turbine with condensate on start-up; this can break these these components components from impact. The blades were designed to handle steam, not water. Turbine casing drains dr ains remove the condensate from the turbine casing during warm-up, securing, maneuvering and other low flow conditions. Turbine Drains: (TWIP) Turbine Water Induction Protection, often abbreviated as TWIP, is the

broad category of equipment that is installed to prevent water damage to steam turbines. Any connection to the turbine is a potential source of water either by induction from external equipment or by accumulation of condensed steam. Steam turbine damage by water induction is a costly economic, safety and reliability concern. TWIP equipment is installed in t he following power plant systems: 





Main steam system piping and drains drains Turbine drain systems

Chapter 3-71 of 157

Chapter 3 Steam Turbines 

Reheat steam systems, piping and drains



Turbine steam seal system, piping and drains



Reheat attemperating system



Main steam attemperator sprays



Turbine extraction systems, piping and drains



Start-up systems



Feedwater heaters,





piping and drains drains Condenser steam and water dumps.

TWIP equipment is installed in the following power plant s ystems: Avoid discharging high-energy bypass steam into i nto the area between the condenser hotwell and the tube bundle Locate the curtain spray and bypass sprayer a safe distance from the condenser tube bundles to allow a sufficient reduction in kinetic energy, so that high-energy steam does not reach areas above and below the tube bundles and cause a recirculation backflow with entrained water toward the turbine. Determine an incidence angle of high-energy steam jets that will avoid reflected velocity vectors toward the turbine exhaust. Water induction can damage steam turbines in several ways. The damage can be caused by the impact of large slugs of water or by the quenching effect of cold water on hot metal. The severity of water damage can vary from minor seal rubs all the way to catastrophic damage to the turbine. Generally, water damage falls into the following categories: Thrust bearing f ailure Damaged Blades Thermal Cracking Rub Damage Permanent warping distortion Secondary Effects Secondary effects include items such as seal packing ring damage, pipe hangar and support damage, damage to instrumentation and controls, etc. Sources of water induction: Water can be inducted into a steam turbine from several sources. The

following are some of the most common sources of water: Motive steam systems Steam attemperation systems Turbine extraction/admission systems Feedwater heaters Turbine drain system Turbine steam seal system Start-up Systems Condenser steam and water dumps (steam bypass) Steam generator generator sources. Turbine bypass systems should be provided with the same level of protection as motive steam piping. These should include include drains and and drain drain pots (if applicable) applicable) with power-operated power-operated drain valves. valves. Attemperators in bypass systems that discharge to the cold reheat system (or any other line connected back to the steam turbine) should be designed to the same requirements on motive steam system attemperators. Non-return valves should be provided in the cold reheat system to prevent

Chapter 3-72 of 157


the reverse flow of bypass steam into the steam turbine. Designers should carefully consider the location, design and orientation of large steam dumps (such as turbine bypasses) into the condenser.

3.44. Atmospheric Relief Diaphragm The atmospheric relief diaphragm is a safety feature which protects the exhaust hood and condenser against excessive steam pressure in case the condenser water for any reason is lost. The device consists of hard rolled silver bearing copper sheet of sufficient area to pass full throttle st eam flow at a safe protective pressure. In normal operation of the turbine with proper vacuum conditions, the diaphragm is dished inward against the supporting grid by atmospheric pressure should the vacuum conditions fail for any reason and the internal exhaust hood pressure raise to approximately 5 psig, it would force the diaphragm outward against the cutting knife. The diaphragm would be cut free as a disk relieving the exhaust pressure to atmosphere.

Figure 3-33 atmospheric relief diaphragm

3.45. Turbine Lube Oil System The function of lubrication is to interpose a film of lubricant such as grease or oil between the moving surfaces in a bearing. Lubrication reduces friction, minimizes wear, provides cooling and excludes water and contaminants from bearing components. The protection of rotating heavy machinery depends greatly on the effective operation and supervision of lubricating oil systems and bearings. Oil lubricated bearings rely on the physical separation of the two bearing surfaces b y a thin film or wedge of oil. In order to establish and maintain this oil film the following conditions must be established. 

There must be relative motion between the two bearing surfaces to build up sufficient pressure within the oil to prevent the film breaking down.

Chapter 3-73 of 157

Chapter 3 Steam Turbines 

There must be an uninterrupted supply of oil available to the bearing.



The bearing surfaces must not be parallel and need a narrow angle between them. This is to enable the oil to be shaped into a thin wedge tapering off in the direction of the motion.

3.46. Turbine Gland Sealing The purpose of the gland steam system is to reduce steam leakage to a minimum and to prevent air ingress. Or Function of the gland sealing system falls into two categories: Seal the turbine glands under all operating conditions, Extract leak-off steam from the turbine glands. Steam leakage leads to the requirement for increased make up; this increases the load on the feed and boiler water treatment chemicals and to a deterioration of the working environment surrounding the power plant. Air ingress leads to a loss of vacuum and hence reduction in plant efficiency, and causes problems of thermal stressing around the gland as well as increases oxygen content of the exhaust steam.

3.47. Condenser A surface condenser is a commonly used term for a water-cooled shell and tube heat exchanger installed on the exhaust steam from a steam turbine in thermal power stations. These condensers are heat exchangers which convert steam from its gaseous to its liquid state at a pressure below atmospheric pressure. Where cooling water is in short supply, an air-cooled condenser is often used. An air-cooled condenser is however significantly more expensive and cannot achieve as low a steam turbine exhaust pressure as a water-cooled surface condenser.

3.48. Specification of Condenser Condenser Type

Surface Type

Type of tubes

I

Material of Tubes

Copper

No. of Tubes

16760

Length of Tubes

9m

Tubes diameter

28mm Table 3-2

3.49. Gland Steam Condenser The gland steam condenser is cooled by the condensate extracted from the main condenser and so acting as a feed heater. The gland steam often shares its condenser with the air ejector reducing the cost of having two units. A fan is fitted to induce a flow through the system without incurring a

Chapter 3-74 of 157


negative pressure in the final pocket as this would allow the ingress of air. This is ensured by the fitting on valves to the exhaust line from the glands so enabling the back pressure to be set.

3.50. Vacuum System For water-cooled surface condensers, the shell's internal vacuum is most commonly supplied by and maintained by an external steam jet ejector system. Such an ejector system uses steam as the motive fluid to remove any non-condensable gases that may be present in the surface condenser. The Venturi effect, which is a particular case of Bernoulli’s principle, applies to the operation of

steam jet ejectors. Motor driven mechanical vacuum pumps, such as the liquid ring type, are also popular for this service.

3.51. Vacuum Breaker The purpose of a Vacuum Breaker Valve is to quickly allow air into the vacuum space of the condenser and low pressure turbine exhaust hood. The vacuum breaker valve is usually located on the steam turbine or the condenser shell/transition. A vacuum breaker valve is typically operable by a controller responsive to losses of load on the steam turbine. Once opened, the vacuum breaker valve will allow air into the steam space to quickly reduce the existing vacuum and hence reduce the acceleration of the steam turbine upon loss of load by the generator.

3.52. Components of a Turbine Lubricating Oil System 1. Main Oil Tank 2. Oil Purification Systems 3. Oil Pumps 4. Oil Coolers 5. Strainers / Filters 6. Instrumentation 7. Jacking Oil Pumps 8. Hydraulic Accumulator

3.53. Turbine Protections 1. Emergency trip pushbutton in control room 2. Boiler Trip, Turbine trip 3. Axial shift displacement 4. Low condenser vacuum 5. Low lube oil pressure 6. LP turbine exhaust hood high temperature 7. Thrust bearing wear 8. Emergency trip at front standard

Chapter 3-75 of 157

Chapter 3 Steam Turbines 9. Low hydraulic fluid pressure 10. Loss of EHC 11. Excessive turbine shaft vibration 12. Loss of two speed signals - either Normal Speed Control or Emergency Over Speed Trip 13. Over Speed Trip 1 14. Over Speed Trip 2

3.54. Steam Turbine Troubleshooting Vibrations

S.no 1

Condition Unbalance

Identifiable by Uniform

vibration

throughout turbine,

Probable cause

the decreasing

slightly under load.

Remedy

1. Sprung shaft

1. Replace shaft.

2. Incorrectly

2. Relocate weights

located balance weights. 3. Displacements of

balance weights. 4. corroded or

eroded blades or buckets 5. Sediment in

blades or buckets 6. Rotor unequally

& balance rotor. 3. Balance rotor. 4. Replace worn

blades or buckets. 5. Replace broken

blades or buckets. 6. Clean blades or

buckets. 7. Consult

manufacturer.

heated. 7. Broken blades or

buckets.

2

Poor

Variable vibration

1. Eccentric

alignment

least noticeable at no

flexibility

with driven

load; becoming worse

coupling

equipment.

under load.

2. Driver & driven

1. Replace flexible

coupling 2. Realign driver

with driven

equipment not

equipment’s as per

aligned properly

manufacturer

at installation.

instructions.

3. Piping strain on

3. Provide support

driver or driven

for piping to

equipment.

relieve strain.

Chapter 3-76 of 157

Chapter 3 Steam Turbines 4. Foundation

4. Solidify

selected

foundation;

unequally.

regrout if necessary.

3

Poor or

Vibration

of 1. Improper grouting. 1. Regrout bed-plate.

inadequate

surrounding structure; 2. Bed-plate

foundation.

constant vibration of

securely

turbine under all load

foundation.

not 2. Tighten foundation bolts.

conditions.

4

Loose parts

localized vibrations with noise at start-up & shut-down.

1. Excessive bearing

clearance. 2. Ball joint of

bearing is loose.

1. Machine off joints

between bearing halves; replace bearing if

3. Loose coupling or

necessary.

coupling bolts.

2. Add shims as

required to tighten bearing; replace worn parts as required. 3. Tighten setscrews

securing coupling to shaft; tighten coupling bolts.

5

Internal

localized

rubbing

with

vibrations 1. Rotating buckets

varying

turbine speed.

with

coming in contact with stationary buckets. 2. Inadequate casing

clearance. 3. Thrust bearing is

1. Check clearance;

adjust as required. 2. Check for chemical

deposits; adjust bearings. 3. Replace thrust

bearing.

worn.

Chapter 3-77 of 157

Chapter 3 Steam Turbines 6

Steam

Unusual noise at the 1. Water coming in 1. Re-evaluate

troubles

intake;

failure

of

strainer.

with steam. 2. Sediment in steam

piping; install a separator ahead of the throttle valve. 2. Test steam for

sediment, acid, or salt. Take corrective action. Table 3-3 General

S.no

Condition

1

Loss of efficiency

Identifiable by Decreased power output

Probable cause 1. Failure of inter-

stage packing,

gland seals or

consumption.

gland seals, or

sealing strips as

sealing strips.

required.

operation

2. Repair or replace

nozzles &

nozzles or

buckets

buckets.

3. Accumulation of

Over speed

1. Replace packing,

with increased steam

2. Failure of

2

Remedy

3. Clean turbine

chemical

internally;

deposits on

change feed

buckets or

water treatment

nozzles

method.

Rapid increase in turbine

1. Loss of load

1. Shut down

R.P.M.

2. Faulty governor

turbine; check

or governor

over speed trip

linkage.

control. 2. Check governor

& governor linkage for malfunction; repair as required. 3

Bearing

Noisy operation;

failure

overheating of operation.

1. Lack of

lubrication.

1. Check oil

supply;

Chapter 3-78 of 157

Chapter 3 Steam Turbines 2. poor grade of oil

increase flow

3. Dirt & other

of oil to

extraneous

bearings;

material in

replace

bearing.

bearing if worn. 2. Drain oil &

replace with good grade of oil as recommended by the turbine manufacturer. Table 3-4

Chapter 3-79 of 157

Chapter

4 4. Decanting Section

GENCO-III is basically a thermal power station that can produces the 1370MW of electricity by heat energy that is produced by the combustion of the furnace oil, diesel or natural gas. However, the large amount of electricity is produced by the combustion of furnace oil because of its lowest cost than diesel. Due to the usage of large amount of furnace oil GENCO-III has a large storage capacity of furnace oil and this can be transported to power station from Karachi by train and by oil tankers. The handling of this fuel is relatively a big task so GECNCO-III built an Individual department for the proper handling and storage of oil. This section consists of storage tanks, oil pumping station and also the oil heaters that heats up the oil to its ignition temperature.

4.1. Oil Testing Lab: Different tests of the furnace oil and the lubrication oil are performed in the oil testing laboratory to check their characteristics. The test on the transformer oil is also performed in this lab. The following tests are performed on the furnace and lube oil: 1. Moisture test 2. Flash point test 3. Viscosity test 4. Specific gravity test 5. Acidity test 6. Solubility test 7. Mechanical impurity test 8. Chlorification test

The furnace oil that is used as a fuel in the burners of the boiler furnace to produce the steam is transported to the TPS through two ways 1. Oil Tankers 2. Train

Page 4-80 of 157

Chapter 4 Furnace Oil Decanting

For unloading of the fuel from oil tankers and train there is separate unloading or decanting station for each. The unloaded fuel oil is initially stored in the underground reservoir; from there it is filled in the main storage tanks. 02 pumps are used to fill the main storage tanks from the oil tankers decanting area. One of them is active (on load) and other is standby. From the decanting area the furnace oil is filled in the storage tanks. From there it is supplied to the burners of the boiler furnace after proper heating. Usually one storage tank is called service tank, from there furnace oil is supplied to the units. The furnace oil is filled in the other tanks first and then filled in the service tanks through recirculation pumps (RCP). The oil in the tanks is kept heated at the temperature 75 C to 80 C. There are total 06 storage tanks for furnace oil each having a volume of 20,000 cubic meters hence each can store 2, 00,00,000 liters. There are 2 diesel oil storage tanks each having capacity of 1000 ton.

4.2. Fuel Flow Cycle

Figure 4-1. Fuel Flow Cycle

4.3. Storage of Fuel The oil is transported by the train or by the oil tanker is tested and then stored to the storage tankers. The oil first of all transfer to the two oil pits inside the ground and then by the help of four oil transfer pump oil is pumped to the storage tanks.

Chapter 4-81 of 157


4.4. Specifications of Furnace Oil Storage Tanks No. of Storage Tanks

06

Capacity of Each

20,000m3

Height of tank

17.3 m

Diameter

39.9 m

Filling Capacity

16.5m Table 4-1

For diesel there are two tanks of oil storage and each has capacity of 1000 m 3. The natural gas is not stored in the plant and it always transported to the plant by the pipeline.

4.5. Recirculation Pump Pumping station consists of two RC (Recirculation) pump that heats up the furnace oil and recirculate the storage tank. One pump is working and one is standby for emergency. Oil from storage tanks passes through the RC pump and at the discharge of the RC Pump there are four steam heaters that heats up the oil to 80 ℃ and recirculate to the storage tanks. Oil steam are shell & tube heat exchanger where steam is in tubes and oil passes from the shell.

4.6. Purpose of RC Pumps 

Preheat Oil to 80 ℃



Transfer oil from Phase # 01 to Phase # 02



Transfer oil from one storage tank to other

Figure 4-2 RC (Recirculation) pump

Chapter 4-82 of 157


4.7. First Lift Pump First lift pump takes the furnace oil from the service tank and supplied to the main heaters. There are total 04 first lift pumps which are operated according to the unit load conditions. The specification of fist lift pump motor is as under. 3 phase 50 Hz Induction Heats up the oil to 110 ℃ 

Transfer oil to service tank



Provide suction head to second lift pump

At the discharge of the first lift pump there are four steam heater that heats up the furnace oil to its ignition temperature. Sr. No.

Parameter of first lifting pump

Units

1

Discharge Pressure

8.5 kg/cm 2

2

Motor Connection

Star

3

Power Factor

0.9

4

Efficiency

90%

5

Voltage

230/400V

6

Speed

2950RPM

7

Current

177/102A Table 4-2

Note: For diesel there are four pumps in which two is in operation and two standby because it

does not require heating for combustion so no heater is installed in this line.

4.8. Second Lift Pump Second lift pumps take the furnace oil from the main heaters and supplied to boilers of the units. There are total 04 second lift pumps which are operated according to the unit load conditions. The temperature of the oil that is supplied to the boiler is 105 C to 120 C. The specification of second lift pump motor is as under; Sr. No.

Parameter of Second lifting pump

Units

1

Discharge Pressure

40 kg/cm2

2

Motor Connection

Star

Chapter 4-83 of 157

Chapter 4 Furnace Oil Decanting 3

Power Factor

0.9

4

Efficiency

5

Voltage

230/400V

6

Speed

2950RPM

7

Current

177/102A

90%

Table 4-3

Figure 4-3 furnace oil from the main heaters

Chapter 4-84 of 157

Chapter

5 5. What is Boiler?

A boiler is an enclosed vessel that provides a means for combustion heat to be transferred into water until it becomes heated water or steam. The hot water or steam under pressure is then usable for transferring the heat to a process. Water is a useful and cheap medium for transferring heat to a process. When water is boiled into steam its volume increases about 1,600 times, producing a force that is almost as explosive as gunpowder. This causes the boiler to be extremely dangerous equipment that must be treated with utmost care. The boiler drum is placed 36m above the ground. The level in the drum is always maintained at zero level (half portion is full with water and half with steam). Steam temperature in the boiler drum is at temperature of 330 ℃ and pressure of 150 kg/cm 2.

5.1. Components of Boiler Drum Boiler drum of GENCO-III TPS consists of the following components, 1. Steam outlet Pipelines 2. Down Comer Tubes 3. Riser Header 4. Water Level Gauge 5. Perforated Sheets 6. Man Hole 7. Surging Plates 8. Heating & Cooling Lines 9. Chemical Dozing Line 10. C.B.D (continuous blow down) 11. Pressure Gauges 12. Feed Water Inlet Connections

5.2. Boiler Systems The boiler system comprises of

Page 5-85 of 157

Chapter 5 Boiler Section 1. Feed Water System 2. Steam System 3. Fuel System The feed water system provides water to the boiler and regulates it automatically to meet the steam

demand. Various valves provide access for maintenance and repair. The steam system collects and controls the steam produced in the boiler. Steam is directed through

a piping system to the point of use. Throughout the system, steam pressure is regulated using valves and checked with steam pressure gauges. The fuel system includes all equipment used to provide fuel to generate the necessary heat. The

equipment required in the fuel system depends on the type of fuel used in t he system.

5.3. Boiler Specification Boiler Manufacturer

Russia

Boiler Capacity

670 TPH

Type of Boiler

Water tube Wilcox & Babcock Type Boiler

Fuel Fired

Furnace Oil, Diesel and Natural Gas 545

Rated Working Temperature Rated Working Pressure

150 kg/cm

Drum Material

High Carbon Steel

Drum Length

24.2 m

Wall Thickness

115 mm

Inner Diameter

1.6 m Table 5-1

5.4. Mini Boiler GENCO-III TPS has a mini boiler which is used to supply steam to different auxiliaries such as for the heating of the furnace oil in order to obtain its ignition temperature heat is required that is given by steam and steam comes from mini boiler.

5.5. Mini Boiler Specification Boiler Manufacturer

Russia

Chapter 5-86 of 157

Chapter 5 Boiler Section Boiler Capacity

50 TPH

Type of Boiler

Water tube Wilcox & Babcock Type Boiler

Fuel Fired

Diesel 250

Rated Working Temperature Rated Working Pressure

13 kg/cm2

Drum Material

High Carbon Steel Table 5-2

5.6. Construction of Boiler Boiler of Genco-III is designed so that it could be constructed from the following components, 1. Furnace 2. Boiler Drum 3. Super Heaters 4. Steam Reheaters 5. Economizer 6. Steam Air Heaters 7. R.A.H (Regenerative Air Heater) 8. G.R.C Fan (Gas Recirculation Fan) 9. I.D & F.D Fan 10. Attemperator 11. Soot Blower 12. Short Blasting System 13. Chimney 14. Hot Box

Chapter 5-87 of 157

Chapter 5 Boiler Section

Figure 5-1 Boiler Drum

5.7. Super Heaters Steam from boiler drum is entre into the super heater for production of superheated steam to run the turbine. In GENCO-III TPS following three types of super heaters are used, 1. Radiation Super Heater 2. Ceiling Super Heater 3. Convection Super Heater

These all are like the tubes of different shapes and dimensions. However, in between these three super heaters an injection system is introduced to maintain the temperature of the superheated steam and also to avoid any accident due to higher temperature. This temperature could be maintained by the device that is called the Attemperator.

Chapter 5-88 of 157


Figure 5-2 Attemperator.

5.8. Steam Reheaters For the increment in the efficiency of the thermal power station steam reheaters is placed after super heaters and before the economizer. This reheat steam is further used in the Intermediate pressure turbine and it totally utilized the energy of the flue gases. In Genco-III TPS two reheaters are placed in the flow path of the flue gases. Reheater could take inlet of steam from High pressure turbine at 330℃ and 27.5kg/cm 2. After passing through the reheater the steam is at 540 ℃ and 25.5kg/cm 2.

Chapter 5-89 of 157


Figure 5-3 steam reheaters

5.9. Furnace Furnace is the most important part of the boiler because it can provide the proper place for the combustion of fuel and also generate heat energy for the production of steam. The floor of the furnace is tilted at an angle of 30 to prevent any accident and also for the proper drain of the unburnt oil from the furnace. Moreover, temperature inside the furnace is 1800 ℃.

Figure 5-4 Furnace

Chapter 5-90 of 157


Figure 5-5 Furnace Gate Type

Chapter 5-91 of 157


5.10. Why Furnace is Important? In thermal power station steam is produced by the firing of the fuel, so main thing fire that depends upon the following three things, 1. Oxygen 2. Fuel 3. Ignition Temperature

So in the furnace oxygen and fuel are mixed for three purposes. 1. Preparation of combustion products 2. Proper combustion of fuel 3. Production of heat energy.

5.11. Types of Furnace In Genco-III TPS there are two types of furnaces are used, 1. Front Fire (Unit 1,2,3) 2. Corner Fire (Unit 4,5,6) Note: Russian could install the front fire furnace where 12-Burners are placed to front wall of the

furnace. Chinese could install the corner fire furnace where 16-Burners are place at the corner of the furnace and make a cyclone while the burning of fuel and the production of the flues.

5.12. Furnace Draft The function of draft in a combustion system is to exhaust the products of combustion into the atmosphere. The draft can be classified into two types namely Natural and Mechanical Draft.

5.13. Natural Draft It is the draft produced by a chimney alone. It is caused by the difference in weight between the column of hot gas inside the chimney and column of outside air of the same height and crosssection.

5.14. Mechanical Draft It is draft artificially produced by fans. Three basic types of drafts that are applied are: 1. Induced Draft 2. Forced Draft 3. Balanced Draft Note: In GENCO-III TPS Balanced draft furnace is used but the pressure inside the furnace is

always maintains slightly negative & less than atmospheric for the proper flow of the flue gases.

Chapter 5-92 of 157


5.15. What could we do when the Unit is to be running at minimum load? When the unit is running at minimum load then the dampers of the I.D. & F.D fan less open and the draft is disturbing and also flue gases could not properly reach to the reheater and temperature difference occurs that may cause an accident and stops the unit. This type of problem may need some proper solution. So, engineer think about it and invent Gas Recirculation Fan (G.R.C Fan) concept.

5.16. Gas Recirculation Fan (G.R.C Fan) G.R.C fan extract a part of flue gases from their flow path and deliver it to the furnace. G.R.C fan performs the following functions. 

To control reheat steam temperature.



To control erosion in the furnace.



To control harmful gases in the chimney.

5.17. Advantages of G.R.C Fan G.R.C fan is placed before R.A.H and after economizer and has the following advantages 

Mass flow of flue gases increases



Flame do not tough with wall



Unburnt gases burnt in the furnace

5.18. Boiler Soot Blower System The boiler in the GENCO-III TPS continuously working and due to this ash lawyer is mounted on the tubes. This soot can be removed by passing steam at higher pressure through the nozzles to the tubes. Steam pressure is 27 kg/cm 2 and temperature is 330 ℃.

5.19. Super Heater Soot Blower System There are four soot blower on the left side and four on the right side. They are moveable and revolving and just hit the steam to the tubes for the removal of ash/soot particles. In 24hours, superheater soot blower could be done in one time at 1 st shift.

5.20. R.A.H Soot Blower System There are two soot blower on the lower and two on the upper side. The steam pressure is 10 kg/cm 2 and temperature is 500 ℃. This soot blowing is done after every 8 hours.

5.21. Economizer Shot Blasting Economizer soot is removed by the short blasting process in which metallic shorts is moved from lower bunker to upper bunker by air blowing at pressure of 1 kg/cm 2 and then strikes on the tubes of the economizer.

Chapter 5-93 of 157


5.22. Flue Gas Cycle Flue gases from the furnace passes through the following components and transfer their heat as far as possible before it goes to the chimney and entre into atmosphere.

Figure 5-6 Flue gases

Chapter 5-94 of 157


Figure 5-7 Flue gases

5.23. Furnace Safeguard Supervisory System (FSSS) The FSSS station consists of the following parts 1. Decanting area 2. Fuel oil tanks 3. First Lift pump 4. Main Heaters 5. Second Lift pump 6. Diesel pumps 7. Recirculation pumps 8. Recirculation heaters 9. Filters 10. control Room

5.24. Burners The important part of the furnace is the burner where the fuel is mixed with the air and burns up for the production of flues from the furnace.

Chapter 5-95 of 157

Chapter 5 Boiler Section In GENCO- III TPS there’s have two types of Burners 1. Stationery Burners (Unit 1,2,3) 2. Tilting Burners (Unit 4,5,6)

5.25. Components of Burner Burner consists of the oil gun in which the steam and oil is mixed up and then this mixture is sprayed in the furnace where it mixes with oxygen then combustion process occurs. There are two types of steam used in the burner. 1. Atomizing Steam (for spray of Fuel) 2. Purging Steam (for Cleaning of Oil Gun when it Choked)

Figure 5-8 Burner Manufacture

Russians

Type of Burner

Stationery Type

Oil Capacity

4.2 t/h

Oil Pressure in Burner

42 kg/cm

No. of Burners in Furnace

12

Type of Firing

Front Fire Furnace Table 5-3

Note: At the starting of unit first pilot burner turns ON that uses gas for firing the Furnace oil and

then after firing it shuts OFF.

5.26. Combustion Air For the better efficiency of the thermal power plant air for the combustion of fuel is to be preheated by the flue gases for the proper combustion of the fuel which generates heat for the formation of steam in the boiler. The Cycle of the combustion air consists of the following components.

Chapter 5-96 of 157

Chapter 5 Boiler Section 

F.D Fan



Steam Air Heater



Regenerative Air Heater (R.A.H)

5.27. Combustion Air Cycle Description First of all, air is taken at the inlet of the F.D fan from the atmosphere and also from the turbine hall. Air is taken from the turbine hall in order to maintain the temperature of the turbine hall and also that the intake air temperature is normally greater than atmospheric because of the heat losses in the turbine hall. This air at 35 ℃ goes to the steam air heater. Steam air heater is the shell & tube heat exchanger where steam is in the pipe and air in the shell. Steam air heater raise then temperature of the air up to 70℃. Now the combustion air goes to the R.A.H for the further increment in their temperature by getting the heat of the flue gases that goes to the chimney for exhaust.

5.28. What is R.A.H and which purpose it is used? R.A.H is the regenerative air heater that raise the temperature of the combustion air by utilizing the energy of the flue gas. In its simplest form R.A.H consists of the strips of the metal mounted on the circular wheel that rotates with the help of motor at 2 RPM. half portion of the R.A.H includes the combustion air and half includes the flue gases. Strips of metal exchange the heat from the flue gases to the combustion air and then finally the combustion air is heated at 250 ℃ and goes to burner for combustion of fuel.

Figure 5-9 regenerative air heater

Chapter 5-97 of 157


Figure 5-10 regenerative air heater

5.29. Economizer Economizer is a device which is used to raise the temperature of the feed water at the inlet flow path of the boiler. Basically economizer is used to preheat the water before it entre into boiler. It is located at the flow path of the flue gas and extract heat from the flue gases and transfer it to the feed water. This process increases the efficiency of the thermal power plant up to 1%. In GECNOIII TPS economizer is located in the flue gas path after the reheater and before R.A.H.

Figure 5-11 Economizer

Chapter 5-98 of 157

Chapter

6 6. What is Cooling Tower?

The component of power plant that removes heat from the water used for condensing steam in condenser.

6.1. Classification of Cooling Tower Cooling are classified into many categories some of them are

Figure 6-1 Cooling classification

6.2. Cooling Tower Section of GENCO-III In GENCO-III TPS closed circuit induced draft cooling tower is used for cooling raw for the condenser to condense steam. The detail of the cooling tower is, 

Raw water comes from the 16 tube wells at taleeri canal through a pipeline to the power plant.



In plant this water is stored in the make-up water pit. Pit is 25-30feet deep.



There’s have five make up water pump that pumps water to the combine pit of all the cooling

of Phase#01.

Page 6-99 of 157

Chapter 6 Cooling Tower Section 

Level of the water checked after every hour and turns the makeup water pump if level of water turns down.



Make up water pump is the three stage centrifugal pump oriented vertically in the pump house.

Figure 6-2 taleeri canal

6.3. Condensate Water Cycle In GENCO-III TPS there are six cooling towers two for each unit that cools the circulating water and then pump it to the condenser for condensing steam. C.W water cycle are as follows, 

Water after condensing the steam moves towards the cooling tower for cooling this water and then recirculate it.



There are two cooling tower for each unit.



Each cooling tower main pipeline is divided into eight small pipes.



Every pipe could further divide into two headers and each header contains 16 pipes.



So, below every fan of cooling tower there’s have 32 tubes that shower water in such a way

that fan extracts heat from water due to their counter flow. 

Every unit has two pumps to circulate water to the condenser.

Chapter 6-100 of 157

Chapter 6 Cooling Tower Section

Figure 6-3 C.W water cycle


Chapter

7 7. Generator

The generator is a device which converts the mechanical energy into electrical energy.

7.1. Working Principle The working principle of generator is based on the Faraday’s law of electromagnetic induction, which states that “The emf (Electromotive force) is always produced in the conductor which is placed in the magnetic field when there is a relative motion between conductor and the magnetic field” .

If the output electrical energy is AC, it is called AC generator or alternator. If the output electrical energy is DC, it is called DC generator. In fact, there is no difference between alternator and DC generator except the way the output is obtained from the generator. In alternator the AC supply is produced in the armature and supply is obtained through slip rings where as in the DC generator the generated AC supply is obtained from the armature through split rings or commutator which converts the AC into DC. The following three things are necessary for the generation of electrical energy. 1. Magnetic field 2. Conductor 3. Relative motion between conductor and Magnetic field

In the small generator the magnetic field is being produced in the stator and t he emf is produced in the rotor through Faraday’s law of electromagnetic induction. The electromagnetic are used in the

generator to produce the magnetic field. In the large generator the magnetic field is produced by the electromagnetic in the rotor and the emf is produced in the stator. The output is taken from the stator because if the output is taken from the rotor, the rotor must have high insulation due to the high voltage induction and it must have heavy insulation which may increase the size of the rotor, and require more power for the prime mover to rotate this heavy rotor.

Page 7-102 of 157

Chapter 7 Electrical Section

7.2. Synchronous Generator The generators used in the TPS are synchronous generator. Synchronous generators are by definition synchronous, meaning that the electrical frequency produced is locked in or synchronized with the mechanical rate of rotation of the generator .

A DC current is applied to the rotor winding, which then produces a rotor magnetic field. The rotor is then turned by a prime mover (e.g. Steam, water etc.) producing a rotating magnetic field. This rotating magnetic field induces a 3-phase set of voltages within the stator windings of the generator. “Field windings” applies to th e windings that produce the main magnetic field in a machine, and “armature windings” applies to the windings where the main voltage is induced. For synchronous machines, the field windings are on the rotor, so the terms “rotor windings” and “field

windings” are used interchangeably. Generally, a synchronous generator must have at least 2 components a) Rotor Windings or Field Windings b) Stator Windings or Armature Windings 1. Salient Pole 2. Non Salient Pole

Figure 7-1 synchronous generator

The rotor of a synchronous generator is a large electromagnet and the magnetic poles on the rotor can either be salient or non-salient construction. Non-salient pole rotors are normally used for rotors with 2 or 4 poles rotor, while salient pole rotors are used for 4 or more poles rotor.


Chapter 7 Electrical Section 

A dc current must be supplied to the field circuit on the rotor. Since the rotor is rotating, a special arrangement is required to get the dc power to its field windings. The common ways are:



Supply the dc power from an external dc source to the rotor by means of slip rings and brushes.



Supply the dc power from a special dc power source mounted directly on the shaft of the synchronous generator.



Slip rings are metal rings completely encircling the shaft of a machine but insulated from it. One end of the dc rotor winding is tied to each of the 2 slip rings on the shaft of the synchronous machine, and a stationary brush rides on each slip ring. A “brush” is a block of graphite like carbon compound th at conducts electricity freely but

has very low friction; hence it doesn’t wear down the slip ring. If the positive end of a dc voltage

source is connected to one brush and the negative end is connected to the other, then the same dc voltage will be applied to the field winding at all times regardless of the angular position or speed of the rotor.

7.3. Some problems with slip rings and brushes. They increase the amount of maintenance required on the machine, since the brushes must be checked for wear regularly. Brush voltage drop can be the cause of significant power losses on machines with larger field currents. Small synchronous machines – use slip rings and brushes.

Larger machines – brushless exciters are used to supply the dc field current. A brushless exciter is a small ac generator with its field circuit mounted on the stator and its armature circuit mounted on the rotor shaft. The 3-phase output of the exciter generator is rectified to direct current by a 3-phase rectifier circuit also mounted on the shaft of the generator, and is then fed to the main dc field circuit. By controlling the small dc field current of the exciter generator (located on the stator), we can adjust the field current on the main machine without slip ri ngs and brushes. Since no mechanical contacts occur between the rotor and stator, a brushless exciter requires less maintenance.

7.4. The Speed of Rotation of a Synchronous Generator Synchronous generators are by definition synchronous, meaning that the electrical frequency produced is locked in or synchronized with the mechanical rate of rotation of the generator. A synchronous generator’s rotor consists of an electromagnet to which direct current is supplied. The



rotor’s magnetic field point in the direction the rotor is turned. Hence, the rate of rotation of the

magnetic field in the machine is related to the stat or electrical frequency by.

 =  ⁄ 7.5. Excitation of Generator Excitation of synchronous generator is done via DC supply which is given to the field winding of the generator to produce the magnetic field. The generator can be classified, with respect to the excitation, as under.

7.6. Separately Excited Generator The generator in which the DC supply is given to the field winding of the generator through the external source is called separately excited generator.

7.7. Self-Excited Generator The generator in which the DC supply is given to the field winding of the generator through its own generated supply is called self-excited generator.

7.8. Synchronous Generator in TPS the main generators used in the TPS Phase-I are separately excited generators. For this purpose, another synchronous generator is installed on the same shaft of the turbine and main generator which is called “Exciter”. The exciter is a self -excited synchronous generator. In the initial startup

the DC supply is given to the field winding (rotor) of the exciter by the DC batteries for 4 seconds. After that the DC batteries are cut off and the DC supply is given to the field of the exciter by its own generated supply after the rectification. The AC supply generated by the exciter is also given to the field winding (rotor) for its excitation after the rectification. The AC produced by the exciter is sent to the rectifier room where it is converted to the controlled DC supply by thyristers. The firing angles of the thyristers are controlled by the AVR (automatic voltage regulator) and hence the excitation of the generator is controlled.

7.9. Exciter generator Exciter generator of the exciter provides independent power supply (3-phase, 50 Hz) to the excitation system. The exciter generator is installed on the same shaft with the turbo generator. The exciter is excited by two water cooling thyristor converters. The thyrister converters are connected in parallel and operate in turn: one is in operation while other is in automatic stand-by duty. The ac and dc circuits of the thyristers includes several knife switches for removal either of the converters from service for repair. Initial excitation of the exciter generator is carried out by a short term connection of the storage batteries through a contactor and rectification bridge.



7.10. Cooling System of Turbo Generator The first question arises here is that why we need cooling of the generator? As the current flow in the stator and rotor of the generator is very high so it increases the temperature of the stator and rotor winding. As a result, the resistance of the stator and rotor windings increases which increase the power losses and may cause the insulation breakdown. Two types of cooling are used in the turbo generator of TPS. 1. Stator cooling 2. Rotor cooling

7.11. Stator cooling The stator of the turbo generator is cooled by the distillated or demineralized (demi) water. For this purpose, a special plant is installed which prepares the demi water for the stator cooling. This demi water is also used for the cooling system of the thyrister converters. The water is passed though the hollow conductors of the stator winding for its cooling. The demi water is necessary for the cooling of the stator winding because raw water is not a pure insulator which may cause the flow of leakage current when passed through stator winding. The demineralized water plant removes the impurities and minerals of the raw water and make it good insulator whose Resistivity is taken at a minimum level of 200 kΩ.cm. The demi water

that passes through the stator winding absorbs the heat of the stator winding making it cool and becomes hot itself. The demi water then passes through heat exchangers (coolers) where its temperature is decreased by the circulating water coming from the cooling towers. This demi water is also passed through the mechanical and magnetic filters before passing through stator winding and thyrister converters.

7.12. Rotor Cooling The rotor cooling is done by the Hydrogen gas. Hydrogen gas is used for the following purposes: 1. Its heat exchange capability is much better than other gases. 2. It is very lighter than other gases so do not overload the rotor. 3. Its preparation is very easy and cheap.

hydrogen gas is filled in the generator and maintained at a pressure of 4kg/cm 2. It takes all the heat of the rotor and cools the rotor winding and gets warmed itself. For the cooling of t he gas there are four gas coolers inside the generator on each corner. Circulating water of the cooling tower is used in the gas cooler for the hydrogen cooling. Hydrogen gas is explosive if it is combined with oxygen under pressure so to avoid any leakage of gas and entrance of air inside the generator the rotor assembly is sealed by the seal oil whose pressure is at least 0.7kg/cm 2 more than hydrogen gas



inside the generator. When the generator is turned off for a long time for maintenance purpose hydrogen is released from the generator in the air using special method. Method involves that firstly fill the generator with CO 2 which release the hydrogen in the air and then in the end air is filled in the generator and CO 2 is released in the air. This method is adopted because if hydrogen is released using air instead of CO 2 then it can cause explosion due to oxygen in the air which will meet hydrogen under pressure in the generator. After maintenance hydrogen gas is refilled in the generator using the reverse process as described above.

7.13. Protections of Generator The following protection are installed for the protection of the generator in TPS Phase-I;

7.14. Longitudinal differential current protection This system is intended to protect against multi-phase short circuit in generator stator winding and at its leads including against double earth fault, one of which being in the generator.

7.15. Lateral differential current protection This system is intended to protect against turn-to-turn short circuit of one phase in the generator stator winding.

7.16. Earth fault protection of stator winding This system is intended to reveal and disconnect one phase earth fault of generator stator winding.

7.17. Differential protection of the unit This system is intended to backup longitudinal differential protection of generator.

7.18. Negative sequence current protection This system is intended to prevent damage of generator in case of overloading by negative sequence current caused by asymmetric load or external asymmetric short circuit and abnormal operating condition of power grid.

7.19. Over current protection against overloading of generator This system is intended for signaling at symmetric overloading of generator stator.

7.20. External symmetrical short circuit protection This system is intended to protect the generator against external symmetric short circuit.

7.21. Protection against asynchronous mode, when excitation loss This system is intended to protect against asynchronous mode. One of the elements of resistance block relay for protection of the unit against external symmetrical short circuit is used.



7.22. Protection of generator rotor against overloading This system is intended to protect against overloading under emergency condition as well as in case of failure of generator excitation system which cause long term flow of current of abnormal value along the rotor winding.

7.23. Earth fault protection in one point of excitation circuit This system is intended to protect the generator in case of earth fault at one point of excitation circuit.

7.24. Protection against voltage increase at generator at idle operation This system is intended to prevent inadmissible increase in voltage at turbo generator and transformer of unit during idle operation of the unit in case of failure of excitation system.

7.25. Zero sequence current protection This system is intended to backup protection operating at one phase short circuit in the 220KV network. It is also used to backup unit protections when short circuit at the 220KV side of the unit.

7.26. Differential protection of the exciter This system is intended to protect against all kind of short circuit in the exciter winding and on its leads.

7.27. Over current protection of exciter against external short circuit This system is intended to protect against over current in the external system of the exciter.

7.28. Switch Yard Mainly there are different but most important things for the protection, measurement, metering and for the other purposes 1. Circuit Breaker 2. Isolator 3. Insulator 4. Insulator strings 5. Bus Bar 6. Current transformer (C.T.) 7. Potential transformer (P.T.) 8. Conductor 9. Control Switch 10. Relays 11. Power Line communication box



7.29. Circuit Breaker This is the basic and the most important part of the switchyard. Isolators are used for its protection because the minimum cost of the circuit breaker which has been installed in KAPCO is of 10 million rupees. So, we are required to provide protection to it to avoid the burning and the familiar of the breaker. Objective: This is installed to protect or making some disconnection or connection part, so that

there can be a bridge between the two parts. This is an automatic device which opens and closes by sensing the characteristics defined by the designer. Suppose if we want to work on the transmission line going to any other region, then we make open the connections of the circuit breaker. On the other hand, if any fault occurs on any side of the breaker, then current transformer which is certainly installed with a breaker senses the abnormal current and sends information to the central control room and also performs some action to protect the system from any accident. Any of the line is no longer in contact with the generator, all lines are coming out from the bus bar and there is a circuit breaker in between the line and the bus bar. So, by chance, if occurs a fault in transmission line then we can easily recover it by opening the breaker. Similarly, the line from the step-up transformer to the bus bar is also protected by a circuit breaker. So, this circuit breaker is a kind of connection and disconnection between the generator, bus bar and the transmission line. So, by this way, the transmission line or substation or bus bar itself and also generator are protected from any kind of small or big accidents.

7.30. The Necessary Capabilities of Breaker: 1. It should be capable of extinguishing the arc without undue delay. 2. It should withstand the transient voltage that appears across the contacts immediately after

the current flow ceases. So it should provide sufficient dielectric strength immediately after the rupture of current. Inside protection: As because of the opening and closing of contacts by some other reasons, arcs

are produced inside the breaker which is dangerous for the life and the characteristics of the breaker. So, these arcs must be quenched. There are many methods for quenching these arcs, e.g. •

Air quenching

•

Gas quenching

•

Vacuum quenching

Types of Circuit Breakers: They can be classified with respect to two criteria •

arc quenching media

•

construction


Chapter 7 Electrical Section With respect to arc quenching media, we have most used types listed below •

The oil circuit breakers

•

The air circuit breakers

•

The SF6 circuit breakers

•

The vacuum type


Chapter

8 The chemical section consists of the following sections 1. Hydrogen plant 2. Demineralization plant 3. Oil testing lab 4. Water testing lab

8.1. Hydrogen Plant Hydrogen plant prepares the hydrogen gas which is used for the cooling of the rotor of the turbo generator. The hydrogen gas is used for the cooling of the rotor of the turbo generator because it has better heat transfer characteristics, cheap and easy preparation and also it is very light and hence do not over load the rotor. The hydrogen is prepared by electrolysis of the water. For this DC supply is given to the electrolyze. This Dc supply is produced after step down of the 6.6 kV s upply to 400 V and then by 3-pahe rectifier. Raw water is used for the preparation of the hydrogen as it supports fast electrolysis action then de-mineralized water. Potassium Hydro oxide (KOH) is used as a catalyst. The oxygen and hydrogen are prepared in the ratio of 1:2.

Figure 8-1 Hydrogen plant

Page 8-111 of 157

Chapter 8 Water Treatment Section

8.2. DC Power Supply The 3-phase 6.6 kV supply is stepped down to 400 V through step down transformers. For this purpose, 02 transformers are installed in the section.

8.3. Electrolyzer The process of electrolyses of the water takes place in the electrolyses. The process in which DC current is passed through the water resulting the separation of the cation and anion is known as electrolyses. The electrolyzer has 25 cells each takes 2.2 V, a total of 55 V DC and a maximum current of 1000 A. The separated hydrogen and oxygen then leaves the electrolyzer on its own ways.

8.4. Separating Column The hydrogen leaving the perforated flash box (PFB) enters the separating column which removes the small parts of alkali from it

8.5. Gas Scrubber Gas scrubber is also called gas washer. It removes the impurities from the hydrogen such as dust particles etc.

8.6. Dryer The dryer dries the hydrogen coming out from the gas scrubber. As gas s crubber do the washing of the hydrogen gas so it has to be dried.

8.7. Receiver Tanks The receiver tanks store the prepared hydrogen gas. For this purpose, 06 receiver tanks are used. The pressure inside the tanks is kept 10kg/cm 2. 03 tanks are for oxygen and 03 are for carbon dioxide storage.

8.8. Demineralization plant “The water which is free of all the impurities, minerals, gases like Oxygen Nitrogen and consists of

only pure water (H 2O) is called demineralized water”. Demineralized plant is used for the preparation of demineralized water. Demineralized water is used for the preparation of steam, for the cooling of stator of generator and for the cooling of thyristors in the excitation system. The plant has total generation capacity of 90 tons/hour. Raw water is used for the preparation of the demi water. Raw water is pumped out by the tube wells and stored in the raw water storage tanks. Demi water is passed through the hollow conductors of stator winding for the stator cooling. It is used for this purpose because demi water acts as an insulator & has a resistivity of 200kOhms.it does not short circuit the windings. Demi water is used for the steam preparation in the boiler for



the following reasons: Raw water contains mineral like Calcium, Magnesium and Sulphur. These minerals cause the stacks and corrosion in the boiler tubes which causes the heat loses and may damage the boiler tubes. The designed loss of the demi water in the steam cycle is 2%. Make up demi water is done in the hot well and feed water tank.

Figure 8-2 Demineralized plant

8.9. Mechanical Clarifier filters In mechanical clarifier filter coal and gravels are is used to remove the unresolved particles from the water.

8.10. Cation filter In the cation filter resins is used which replaces the Na+ & Ca 2+ ions in the water from the + H ions. In the end water becomes acidic.

8.11. Decarbonized exhaust It removes the carbonates from the water.CO 2 is removed by showering of the water against air. It is also known as degasifier.

8.12. Anion filter In Anion filter castic soda (NaOH) is used which replaces the Cl- or SO4 ions with the OH- ions forming partial demi water.

8.13. Cation 2nd filter It also removes the positive ions from the water. Mixed filter: In the mixed filter both the remaining anions and cations are removed. The water leaving the mixed bed is the pure distilled water.

8.14. Storage tanks This prepared demineralized water is then stored in the storage tanks.



8.15. Water treatment Ammonium hydroxide, Hydrazine and Trisodium phosphate are dozed at different points in the boiler such as boiler drum, for water treatment. The nature of this water is acidic, to minimize the acidity of this water ammonium hydroxide (NH 4OH) is used. Hydrazine (N 2H4) removes the Oxygen from water and protects the boiler tubes against corrosion. Trisodium phosphate (Na 3PO4) is used in the boiler drum which removes the Ca, Mg and adds Na.

8.16. Installed Capacity in Pakistan (GW & Percentage)

Units

787, 3% 256, 1%

7115, 29%

7663, 31%

9085, 36%

Hydro

IPP's Thermal

Thermal

Nuclear

Wind

Graphs 8-1



8.17. Cost of Electricity

5 0 . 0 2

4 . 9 1

6 8 . 9 1 8 5 . 6 1

5 2 . 4 1

H W K R E P T S O C

9 0 . 1 1

2010

2011

2012

2013

2014

2015

YEARS

Graphs 8-2

8.18. Generation Data Dep.Cap. (MW) 7 1 9 5

Generation (MKWh) 2 6 1 6

0 9 3 5

Units Sold (MKWh) 5 5 0 6

0 0 6 5

5 4 0 6

5 6 4 5

5 8 4 5

0 0 0 1

0 0 0 1

0 0 0 1

0 0 0 1

FY 2007-08

FY 2008-09

FY 2009-10

FY 2010-11

Graphs 8-3


FINAL SEMESTER INDUSTRIAL INTERNSHIP REPORT GENCO THERMAL POWER STATION III MUZAFFARGARH

DEPARTMENT OF MECHANICAL ENGINEERING & TECHNOLOGY

Muhammad Nawaz Sharif University of Engineering & Technology Multan Submitted By Hammad Naeem

2012-BT-MECH-101

Waqas Nazir

2012-BT-MECH-111

Session 2012-2016

Chapter

9 9. Introduction

Qadri-Group is foundry-man and machinery-builders, the roots of Qadri family-business trace back to over a century. Qadri-Group today enjoys pre-eminence as manufacturers of heavy industrial plant. Qadri-Group specialize in the manufacture of plant & equipment for various sectors including sugar, cement, steel, power generation, chemical and petrochemical. Qadri-Group is professionally managed business-group geared up to meet modern day challenges with the zeal to work for the land where we were born. The process of establishing new companies within the Qadri-Group is ongoing. In doing so, conscious effort has always been made to inculcate Qadri-Family values in all Group-companies. Effort has also always been made for the scope of activities of each Groupcompany to complement that of the others and so to reinforce the Qadri-Group at the center. In this sense, the pattern of our growth has been centripetal. At the same time, Qadri-Group attach high pri ority to forge links with the world’s leading technology companies for plant & equipment falling under our scope of manufacture. The resultant synergy has enabled us to offer tailor made cost effective solutions and latest equipment to customers at home and abroad. This engineering and manufacturing company comprises of two main production units: 

Mechanical Works



Foundry & Forge Works

The major facilities of this integrated company include Design and Engineering, Fabrication, Machine shops, Steel Foundry, Forging, Heat treatment, Pattern Shop, Assembly & Tool Room and a compressive Quality Assurance is set-up in addition to other infrastructure facilities

9.1. QADRI BROTHERS (PVT) LTD. (Unit-1) Steel foundry annually producing 5000 tons’ castings with max. single- pour 30000 kg’s. Melting

equipment includes medium and mains frequency electric induction furnaces to produce a wide range of material grades including carbon steels, alloy steels, SG iron and stainless steels.

Page 9-118 of 157

Chapter 9 QadBros Engineering Services

9.2. QADRI BROTHERS (PVT) LTD. (Unit-2) Modern steel foundry with an annual capacity to produce 7500 tons’ castings with max. single -pour 35000 kg’s. Melting equipment includes medium and mains frequency electric induction furnaces

to produce a wide range of material grades including carbon steels, alloy steels, SG iron and stainless steels.

9.3. QADCAST (PVT) LTD. Modern iron foundry with an annual capacity to produce 9000 tons’ medium & heavy alloy cast

iron and non-ferrous castings with maximum single- pour 45000 kg’s. Melting equipment includes large capacity coke-fired cupola furnaces as well as medium frequency electric induction furnaces to produce material grades including wide range of alloy cast irons, SG iron, wear resistant steel, bronze and stainless

steels.

9.4. QADRI FOUNDRY (PVT) LTD. Jobbing-type foundry located in the port-city of Karachi. It caters to the needs of our Karachi-based customers for small & medium cast iron and non-ferrous castings produced with a maximum single pour 2500 kg’s. “All of our foundry-works use state of the art globally renowned casting simulation software MAGMASOFT”

9.5. QADBROS ENGINEERING (PVT) LTD. Heavy mechanical works with facilities which, combined with those of the sister-company. Qadri Engineering, make it Pakistan’s largest heavy machining facility and one of our region’s largest

manufacturers of heavy plant &equipment. The Company has a wide customer base within industrial sectors including sugar, cement, steel, energy, fertilizer, general industry. The Company also leads QADRI-Group in its interface with global partners and with worldwide customers.

9.6. QADRI ENGINEERING (PVT) LTD Heavy mechanical works with facilities similar to but much larger than the sister-company Qadbros Engineering. The Company’s shop -floors are equipped with an array of medium and extra-large

machine tools with the capacity to handle single work-pieces weighing up to 100 tons. Like all other companies within the QADRI-Group, this Company has 1 MW captive power installed to ensure uninterrupted operations.

9.7. QADRI FORGE (subsidiary of QADRI BROTHER Conventional facility using free-forge technology to produce forgings weighing up to max. 3000 kg’s per piece.


Chapter 9 QadBros Engineering Services

9.8. QADRI SONS (PVT) LTD Trading company engaged in the retail & wholesale of hot-rolled structural steel and bars.

9.9. KASHIF TRADEHOUSE (PVT) LTD Trading company engaged in the import of raw materials, intermediate materials, alloying metals required by QADRI- Group’s manufacturing units as well as by the foundry and engineering industry at large.

9.10. Departments 1. Sales and Marketing Department 2. Design and Engineering Department 3. Production Planning and Control Department 4. Production work Shops (1 & 2) 5. Quality Assurance Department 6. Project Management Department 7. Human Resources Department

9.11. Facilities 1. Fabrication 2. Machining 3. Heat Treatment 4. Casting 5. Forging 6. Tool Making 7. Assembly 8. Design and Engineering with well-equipped Computer Aided Design (CAD) facility 9. Well-equipped Quality Assurance Department with ISO 9001 Certification and

authorization to use ASME 14 for fabrication

9.12. Products 

Sugar Plants



Cement Plants



Over Head Traveling Cranes


Chapter 9 QadBros Engineering Services 

General Steel Structures



Highly Sophisticated Castings and Forgings



Paper industry parts



Fertilizer industry parts

9.13. Quality Certification 

ISO 9001



UKAS

9.14. Scope Design, engineering, manufacturing and commissioning of plants and machinery including cement, sugar, cranes, steel structures, plain and alloyed steel castings, free and automatic die forgings, steel billets and other similar heavy engineering equipment.


Chapter

10 10. Introduction PPC department has been organized with the objective of improving company’s performance. The

department is comprising of the following objectives; Make complete Plan for the Execution of Project. Provide digital data to every shop section in collaboration with EDP to make ease in processing and manufacturing of a particular job. Manage Inventory in collaboration with Material handling section. Make feasibility and Quantitative detail as well as processing planning and tool designing in collaboration with Production Technology department. Manage input and output of material in collaboration with Dispatch Cell.

10.1. Production, Planning & Control Sections In Qadbros Engineering Ltd. PPC department is properly organized and work as team with the following sections 1. Project Planning 2. EDP/CP 3. Material Handling

a) MMG b) General Stores 4. Production Technology

a) Feasibility and Quantitative Detail b) Process Planning & Tool Designing 5. Dispatch cell 6. ICR

10.2. Project Planning Project Planning department are established to achieve the following objectives with exact milestone in organized way to ensure its performance,

Page 10-122 of 157

Chapter 10 Production, Planning & Control

To ensure receipts of all drawings and documentation from design as per contact and accelerate the schedule for production and procurement. To issue “material purchase requirement” to MMG. To prepare “bill of material” to be purchased.

To coordinate with the production technology for preparation of necessary documents for production. To prepare and issue job orders and follow up. To suggest alternate materials from stock to design. To prepare data and reports for ICR and for survey by FBR.

10.3. Core Planning Core planning department also called Electronic data processing department performs the following functions, Master schedule planning Order activity planning Monitoring all schedules / shop scheduling Maintenance of balance order position. Monthly sales and production reports Sales / production budget. Project review. Meeting and follow up. Data entry, loading data and processing data

10.4. Material Handling Material handling department works in collaboration with two departments to ensure its objectives

10.5. Material Management Group Material requirement planning Indenting and follow up of indents To keep update purchase status for all the project demands Establish stock levels for general consumable items and raw materials Issuance of materials to the appropriate job To keep and maintain update levels for the store items To look after stores and related things



Figure 10-1 Material requirement planning

10.6. General Stores To receive, issue all the materials, and equipment in stores as per laid down procedure Maintain detailed record of store movements Maintain stock location system Maintain daily submission of issue and receipt statement to concerned department to keep store areas secure and organized

10.7. Production Technology Department Production Technology Department work to achieve the following objectives, Feasibility study and quantitative details of cli ent’s requirements for cost estimate. Prepare details per list, route cards, cutting plans, time sheets and process maps for all the processes. Designing of all types of press tools, dies, templates, jigs and fixtures Prepare drawings for machinery components, cutting planes, marking templates for shops etc.

10.8. Dispatch Cell Dispatch cell works under PPC and has following objectives, To receive finished jobs from shops To draw standard items from store for dispatch to customer To organize packing To organize transportation Ensure complete accurate documentation with each product



10.9. Work Procedure of PPC

Figure 10-2 PPC


Chapter

11 11. Introduction Fabrication shop located in mechanical works QADBROS is setup to create an interracial fault on

materials/workpieces in order to obtain any type of useful assembly or equipment. In QADBROS Fabrication shop consists of five bays i.e., one heavy bay, two medium bays and two small bays. Bays are divided as per the capacity of the cranes.

11.1. Fabrication Techniques Metal fabrication is a value added process that involves the construction of machines and structures from various raw materials. A fabrication shop will bid on a job, usually based on the engineering drawings.

Figure 11-1 Metal fabrication

Page 11-126 of 157

Chapter 11 Fabrication Shop

11.2. Planning and Control (CTC) CTC stands for Central Technical Cell . Basically it’s a planning and control section of Fabrication, in this section different drawings are analyzed and then sent to different sections of fabrication shop depending upon the job and capacity of the shop. The main plans of CTC fabrication are as follows, •

Job feeding to shop

•

Planning

•

Material check

•

Observation from manufacturing till sale.

Figure 11-2 Central Technical Cell

11.3. Marking and Layout Section Layout section of fabrication shop is established to mark the layout on the work materials as per cutting plans and delivered the desired part to the specific section according to the planning of CTC after performing cutting operation. Layout section of fabrication shop consists of the following sections, 1. Marking Sections •

Marking as per Drawing

•

Marking as per Paper Template

•

Marking as per Metallic Template (Used for Mass Production)

2. Cutting Section •

Mechanical Cutting

•

Flame Cutting 

Manual Gas Cutting


Chapter 11 Fabrication Shop 

Semiautomatic Gas Cutting



Parallel Cutting Machine

11.4. Marking Section Marking out or layout is the process of transferring a design or pattern to a work piece, as the first step in the manufacturing process. It is performed in many industries. Marking out consists of transferring the dimensions from the plan to the work piece in preparation for the next step, machining or manufacture.

11.5. Marking Tools Typically following marking tools are utilized in Qadbros to transform any pattern t o work piece,

11.6. Surface plate or marking out table It provides a true surface from which to work.

11.7. Angle Plates It assists in holding the work piece perpendicular to the table.

11.8. Scriber It is the equivalent of a pen or pencil. It literally scratches the metal surface leaving behind a fine, bright line.

11.9. Height Gauge or Scribing Block It allows lines to be scribed at a pre- set distance, from the table’s surface.

11.10. Surface Gauge An ungraduated comparison measuring tool that performs much the same function as the Vernier height gage. It is often used in conjunction with a dial indicator and a precision height gauge.

11.11. Marking Blue To provide a usable writing surface by covering any existing scratches and providing a contrasting background.

11.12. Protractor To assist in the transfer of angular measurements.

11.13. Tri-Square To transfer 90° angles to the work piece.

11.14. Punches It pricks or Centre punch to create permanent marks or dimples for drill bits to start in Ball peen hammer used in conjunction with the punches to provide the striking blow needed.



11.15. Dividers or Measuring Compass It is used for marking out circles of any desired radius.

11.16. Cutting Section or Flame Cutting Flame cutting facilities in layout section includes the following machines •

Manual Gas Cutting

•

Semiautomatic Gas Cutting

•

Parallel Cutting Machine

For all these cutting machine mechanism of cutting is same but the operation is different as per the requirement,

11.17. What is flame cutting Gas cutting is a process of preheating carbon steel to its combustion temperature, then burning it rapidly by means of a regulated jet of oxygen. A cutting torch is used for this operation.

11.18. Process The process is primarily a chemical one. It is based on the chemical relationship of oxygen to iron metals that have been heated to a temperature of 1400° to 1600° F (760° to 871°C). Only the metal within the direct path of the oxygen jet is affected. In cutting, a “kerf” is formed. This is a narrow slit having uniformly smooth and parallel walls. A skilled workman using machine cutting torch can maintain the following tolerances with respect to squarenes and straight alignment of the cut surface: 1/32nd of an inch (.79mm) on plate thickness up to 4 inches (100mm) and 1/16th of an inch (1.58mm) on plate thicknesses from 4 to 12 inches (100 to 300 mm). In actual gas cutting, the iron or steel removed from the “kerf” is not entirely burned or consumed

by the oxygen. About 30 to 40 percent of the metal is washed out of the cut as unconsumed or metallic iron due to the eroding effect of the oxygen jet. This scouring can be seen if the sides of the kerf are inspected, because drag lines will be faintly etched on the faces of the metal. For an incorrect cut, these drag lines will be more pronounced. The inspection and analysis of these drag lines can be used to improve cutting technique. (see illustration of drag lines below) •

Vertical lines – zero drag

•

Drag measured against plate thickness, for example, 10% drag means a lag of 10% plate thickness

11.19. Flame Cutting Equipment’s Since the oxygen-cutting process involves directing a high-pressure jet of oxygen continuously on to an area of steel that has been previously heated to ignition temperature, the basic equipment’ s

are.


Chapter 11 Fabrication Shop 





Cutting Torch Nozzle Cutting Attachments

11.20. Joining Operations Most of the time during fabrication of metals three types of joining operations are used 

Soldering



Brazing



Welding

11.21. Soldering The joining process in which solder mostly tin wire is used to join the parts together. Soldering is done to prevent leakage in joints in rockets and missiles. This process is mostly used in PCB manufacturing industries and it’s the best process for electrical joints.

11.22. Brazing The joining process in which the parts are joined together by applying molten metal of melting temperature less than 450

typically is of brass. This process is just like as gas welding process

and mostly used in precision works.

11.23. Welding Welding is a fabrication or sculptural process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the work pieces and adding a filler material to form a pool of molten material (the weld pool) that cools to become strong joint, with pressure sometimes used in conjunction with heat, or by itself, to produce the weld. This is in contrast with soldering and brazing, which involve melting a lower-melting-point material between the work pieces to form a bond between them, without melting the work pieces. So, welding is basically the Joining metals through heating them to a molten state and fusing them together is called the welding

11.24. Classification of Welding 11.25. SMAW Shielded metal arc welding (SMAW) is a process that melts and joins metals by heating them with an arc established between a sticklike covered electrode and it is often called stick welding. The electrode holder is connected through a welding cable to one terminal of the power source and the workpiece is connected through a second cable to the other terminal of the power source.



Figure 11-3 Shielded metal arc welding

The heat of the arc causes both the core wire and the flux covering at the electrode tip to melt off as droplets the molten metal collects in the weld pool and solidifies into the weld metal. The lighter molten flux, on the other hand, floats on the pool surface and solidifies into a slag layer at the top of the weld metal.

11.26. Purpose of Flux on Welding Electrode Flux on the electrode performs four functions as follows 

Protection from atmosphere



Deoxidizer



Arc Stabilization



Metallic Addition

11.27. GTAW Gas – tungsten arc welding (GTAW) is a process that melts and joins metals by heating them with an arc established between a non-consumable tungsten electrode and the metals. The torch holding the tungsten electrode is connected to a shielding gas cylinder as well as one terminal of the power source. The tungsten electrode is usually in contact with a water-cooled copper tube, called the contact tube, which is connected to the welding cable (cable 1) from the terminal. This allows both the welding current from the power source to enter the electrode and the electrode to be cooled to prevent overheating. The workpiece is connected to the other terminal of the power source through a different cable (cable 2). Shielding gas goes through the torch body and is directed by a nozzle toward the weld pool to protect it from the air. Protection from the air is much better in GTAW than in SMAW because an inert gas such as argon or helium is usually used as the shielding gas and because the shielding gas is directed toward the weld pool. For this reason, GTAW is also called tungsten – inert gas (TIG).



11.28. Polarity of Current in GTAW 

DCEN (Direct Current Electrode Negative)



DCEP (Direct Current Electrode Positive)



AC Current

11.29. GMAW Gas – metal arc welding (GMAW) is a process that melts and joins metals by heating them with an arc established between a continuously fed filler wire electrode and the metals. Shielding of the arc and the molten weld pool is often obtained by using inert gases such as argon and helium, and this is why GMAW is also called the metal – inert gas (MIG)welding process. Since non inert gases, particularly CO2, are also used, GMAW seems a more appropriate name. This is the most widely used arc welding process for aluminum alloys.

11.30. SAW Submerged arc welding (SAW) is a process that melts and joins metals by heating them with an arc established between a consumable wire electrode and the metals, with the arc being shielded by a molten slag and granular flux. This process differs from the arc welding processes discussed so far in that the arc is submerged and thus invisible. The flux is supplied from a hopper, which travels with the torch. No shielding gas is needed because the molten metal is separated from the air by the molten slag and granular flux. Direct-current electrode positive is most often used. However, at very high welding currents (e.g., above 900A) AC is preferred in order to minimize arc blow.

11.31. Recommendations 

The exhaust system is not sufficient enough and more units should be installed especially near the welding areas to suck out the welding gases produced.



There is no proper ventilation as most of the windows are closed/jammed.



Welding fumes are very hazardous and workers should be provided with free face masks, gloves, goggles, helmets etc. with strict and proper checking of the defaulters.



More advanced machines like CNC laser cutting and water jet cutter should be installed and replace manual machines to save time and increase production and efficiency.



Finished products placed outside the fabrication shop should have a proper storage team as they are affected by corrosion, moisture and rain resulting in damage of the goods to be sent to the consumers. Such materials should be used that are corrosion resistant. These machines not in working condition should be immediately repaired without any delay no matter what the cost is.



Welding defects should be avoided. Further details are provided in NDT Section.



Quality assurance is the main priority and supervisors should check where the workers are doing wrong to save time in case the goods are rejected.


Chapter

12 12. Introduction Machine shop is considered as one of the most important shops of as it contributes a major part in

the income of the industry. In this shop different type of actions and works can be performed with the help of different machines each perform unique work which is performed under the supervision of experienced workers having experience of decades which definitely cannot be compared with the theoretical work of anyone else. Machine shop engineers always try to complete job with minimum cost but at the same time quality would also not be sacrificed so lots of factors are included in a shop which makes it unique and compatible. A theory named as FIVE M’s is adopted by different industries in order to survive in this competitive market which is as following

12.1. Five M’s Here following five M`s are followed for the purpose of good management 1. Man power 2. Equipment/Machines 3. Methods 4. Materials 5. Money

12.2. Division of Shop Due to the load of job the machine shop is divided into two main sections 1. Machine shop 1 2. Machine shop 2

12.3. Sequence of Operation “It is defined as the plan through which workers and engineers have to complete the required job according to availability of machines “

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Chapter 12 Machine Shop

12.4. Explanation The whole procedure of job making in machine shop may be summarize in an easy way that at first the request of job is received by PPS department in machine shop they analyses it carefully and make drawings that helps workers to understand their job along with the plan which makes easy for them to accomplish goal within the time limit according to the availability of machines in machine shop or other shops machines may also be used to fulfil the job. This job then forwarded to Incharge of section according to the size of the job so it’s the duty of Incharge and engineers available there to assign the job to any experienced worker which can effectively perform the job with minimum usage of material it does not only save material but also so many other things like cost, time, electricity and man power required for that job.

12.5. Raw Materials Used in Machine Shop The selection of best material is an important task performed by specially experienced persons, the task is not only to choose the appropriate material for the job but it should be economical which decrease its cost in market but the quality may not be sacrificed. 

Mild Steel



Steel 45



Stainless Steel



Bronze



Brass



Ferrous Metal



Nonferrous Metal

12.6. Products Seen in Machine Shop The tour of machine shop helps us to witness the machining and other process on the required job. It also helps to understand the modern requirement of the industries, sugar mills, etc. Following is the list of jobs we saw in machine shop. 

Pulley



Cement plant parts



Parts of sugar mill



Barrel



Gears



Fertilizer industry parts



12.7. Tools used in Machine Shop Tool is probably one of the most important component of any sort of machine. The ability and durability of tool predicts the quality and nature of machining on the job. There are lots of tools but few important tools we saw in machine shop are: 

Boring Tool

Used in the process of boring. 

High Speed Steel (HSS)

Used for different sort of purposes including threading. Mostly used in lathe machines. 

Tapping Tool

Used for internal threading. 

Broaching Tool

Used to produce splines. 

Turning Tool

Used for turning operation.

12.8. Machines/Equipment installed in Machine Shop Machine shop 1 consist of various kinds of machines each having its unique identity and importance in this sector. This kind may not only be classified as for functions only but the maximum capacity of the machine may also be considered so according to the capacity of job and the availability of crane the machine shop 1 is divided into two bays which are as follows 

Small bay



Medium bay

In these bays the following machines are installed for the production of various types of simple and complex objects, 

Lathe machine (Three jaws and four jaws chucks)



Planer machine



Shaper Machine



Milling machine



Cylindrical Grinding Machine



Drilling machine



HDL (Heavy duty lathe)



BVT (Boring vertical turret lathe machine)


Chapter 12 Machine Shop 

Horizontal lathe machine



Radial drilling machine



Double housing planner

12.9. Machining Operations 12.10. Machining 

A material removal process in which a sharp cutting tool is used to mechanically cutaway material so that the desired part geometry remains.



Most common application includes to shape metal parts.



Machining is the most versatile and accurate of all manufacturing processes in its capability to produce a diversity of part geometries and geometric features (e.g. Screw threads, gear t eeth, flat surfaces).

12.11. Turning and Related Operations 12.12. Turning A single point cutting tool removes material from a rotating work piece to generate cylindrical shape. The tool is fed linearly in a direction parallel to the axis of rotation Performed on a machine tool called a lathe.

12.13. Facing Tool is fed radially inward to create a flat surface.

12.14. Chamfering Cutting edge cuts an angle on the corner of the cylinder, forming a "chamfer".

12.15. Threading Pointed form tool is fed linearly across surface of rotating work part parallel to axis of rotational a large feed rate, thus creating threads.

12.16. Lathe Machines 

Most lathe machines are horizontal but vertical lathe machines are also used for jobs with large diameter relative to the length and for heavy work



The size of the lathe is designated by swing and maximum distance between centers



Swing is the maximum work part diameter that can be rotated in the spindle



Maximum distance between centers indicate the maximum length of a workpiece that can be mounted between headstock and tailstock center



350 mm x 1.2 m lathe means a swing of 350 mm and maximum distance between center of 1.2 m



12.17. Methods of Holding the Work in a Lathe There are four common methods used to hold work parts in turning-to grasp the work, center and support it in position along the spindle axis, and rotate it: 1. Holding the work between centers 2. Chuck 3. Collet 4. Face plate

12.18. Boring Machine 

Boring is similar to turning. It uses a single-point tool against a rotating work part Difference between boring and turning:



Boring is performed on the inside diameter of an existing hole



Turning is performed on the outside diameter of an existing cylinder



In effect, boring is an internal turning operation



Machine tools used to perform boring operations are called boring machines



Boring machines may be Horizontal or vertical - refers to the orientation of the axis of rotation of machine spindle

12.19. Vertical Boring Mill 

A vertical boring mill – for large, heavy work parts



Usually the work part diameter is greater than its length



Typical boring machine can position and feed several cutting tools simultaneously

12.20. Drilling 

Machining operation used to create a round hole in a work part



Contrasts with boring which can only enlarge an existing hole



Cutting tool called a drill or drill bit-a rotating cylindrical tool which has two cutting edges on its working end



Customarily performed on a drill press

12.21. Milling Machine and Operation 

A machining operation in which work is fed past a rotating tool with multiple cutting edges



Axis of tool rotation is perpendicular to feed direction



Creates a planar surface; other geometries possible either by cutter path or s hape



Owing to the variety of shapes possible and its high production rates, milling is one of the most versatile and widely used machining operations



Milling is an interrupted cutting operation-the teeth of the milling cutter enter and exit work during each revolution


Chapter 12 Machine Shop 

Cutting tool called a milling cutter, cutting edges called "teeth"



Machine tool called a milling machine

12.22. Basic Types of Milling Operations 12.23. Peripheral milling or plain milling: 

Cutter axis is parallel to surface being machined



Cutting edges on outside periphery of cutter

12.24. Face milling 

Cutter axis is perpendicular to surface being milled



Cutting edges on both the end and outside periphery of the cutter

12.25. Shaper Machine A shaper is a type of machine tool that uses linear relative motion between the work piece and a single-point cutting tool to machine a linear toolpath. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. (Adding axes of motion can yield helical toolpaths, has also done in helical planning.) A shaper is analogous to a planner, but smaller, and with the cutter riding a ram that moves above a stationary work piece, rather than the entire work piece moving beneath the cutter. The ram is moved back and forth typically by a crank inside the column; hydraulically actuated shapers also exist.

12.26. Planar Machine A planer is a type of metalworking machine tool that uses linear relative motion between the work piece and a single-point cutting tool to machine a linear toolpath. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. A planer is analogous to a shaper, but larger, and with the entire work piece moving on a table beneath the cutter, instead of the cutter riding a ram that moves above a stationary work piece. The table is moved back and forth on the bed beneath the cutting head either by mechanical means, such as a rack and pinion drive or a leadscrew, or by a hydraulic cylinder.

12.27. Pedestal Grinding Machine This particular machine performs the actions just similar to the grinding machine. They are used for shinning and facing the cutting tools it may be used for sharping the tip also. Silicon carbide wheel is used for grinding according to the worker daily they have to change that wheel 3 to 4 times as it all consumes while grinding the metal piece or cutting tool.

12.28. Production Planning Section Production Planning Section is an important section of machine shop which plans the whole job making procedure and way through which it has to be treated. Another important action which it



performs is the preparation of technical drawings which helps workers to understand the proper dimensions of the job along with the properties of material which is required for that specific job.

12.29. Working Monthly schedule Job order Receiving The job order can further be classified as 1. Drawing sets 2. Component list 3. Cutting plan 4. Drawing set planning 5. Loading 6. Machining 7. Inspection 8. Assembly 9. Dispatch cell

12.30. Routes The route of job may differ according to its requirement but normally it follows following route

12.31. Route 1 1. Forging process 2. Heat treatment shop 3. Machining 4. Assembly shop

12.32. Route 2 1. Fabrication shop 2. Machining 3. Assembly shop

12.33. Route 3 1. Casting 2. Heat treatment shop


Chapter 12 Machine Shop 3. Machining 4. Assembly shop


All lathe machines are operated manually which not only results in delay of job completion but it then also totally depends on the experience and qualification of that specific worker.



Maintenance issues also affecting the productivity of machine shop due to which the assembly shop is just bounded to specific small area not large enough for assembling of different jobs.



First aid facilities are not enough. Workers prefer not to wear uniform which leads them in extreme danger of damaging themselves or may lose any organ.



Cranes does not have bells so the people working on ground used to work in extreme danger while cranes loading heavy jobs over their heads.



The machines are old enough to work perfectly as it may also be concluded through the installation dates of each machine (mentioned in the specifications of machine). So, modern machinery should be introduced which may help to increase the production along with the quality and durability of the job.


Chapter

13 13. Introduction This Shop involves various heating and cooling procedures performed to effect microstructural

changes in a material, which in turn affect its mechanical properties. Heat treatment operations are performed in Qadbros at various times during its manufacturing sequences. In some cases, the treatment is applied prior to shaping. In other cases, heat treatment is used to relieve the effects of strain hardening that occur during forming, so that the material can be subjected to further deformation. Heat treatment is also performed at or near the end of the sequence to achieve the final strength and hardness required in the finished product. Heat Treatment is process of heating a material to a specific temperature, then cooling at a specific rate to achieve specific mechanical properties. Iron-Iron Carbide Phase Diagram (Iron Carbon Phase Diagram) is an important guide for heat treatment of different types of plain carbon steel.

13.1. Selective Surface Hardening / Case Hardening When we require different HRC at different surface and regions then case hardening is applied. Different case hardening methods are: 1. Flame hardening 2. Surface Hardening and then machining

Methods used in Qadbros are flame hardening, and surface hardening + machining.

13.2. Flame hardening This method involves heating of the work surface by means of one or more torches followed by rapid quenching via water. Fuel used is acetylene. Usually used for large and small gears. Typical hardness depth is about 2.5 mm both manual and automatic flame hardening facility is available at Qadbros.


Few types of machinery were under maintenance and hence must be repaired.



Modern heat treatment techniques like laser beam heating and electron beam heating are not used and are not provided. They must be introduced to increase the quality and performance.

Page 13-141 of 157

Chapter

14 14. Introduction The other facility of material testing provided by Qadbros is the non-destructive testing of the

material which means such methods of testing in which the breakage or damage of the material is not involved. An example of this testing is the use of X-ray technology to locate the defects internally. We can say that it undertakes ultrasonic, die penetrant and magnetic particles testing for surface cracks, voids, blow holes, porosity and cavity etc. in welds, castings and forgings.

14.1. NDT Techniques There are following tests which are being performed by the lab: 1. Ultrasonic Testing (UT) 2. Magnetic Particle Testing(MT) 3. Dye Penetrant Test (PT) 4. Hardness test 5. Chemical test

14.2. Ultrasonic Testing (UT) Ultrasonic testing (UT) is a family of non-destructive testing techniques based on the propagation of ultrasonic waves in the object or material tested. A typical UT inspection system consists of several functional units, such as the pulser/receiver, transducer, and display devices. A pulser/receiver is an electronic device that can produce high voltage electrical pulses. Driven by the pulser, the transducer generates high frequency ultrasonic energy. The sound energy is introduced and propagates through the materials in the form of waves. When there is a discontinuity (such as a crack) in the wave path, part of the energy will be reflected back from the flaw surface. The reflected wave signal is transformed into an electrical signal by the transducer and is displayed on a screen. The reflected signal strength is displayed versus the time from signal generation to when an echo was received. Signal travel time can be directly related to

Page 14-142 of 157

Chapter 14 Non-Destructive Testing

the distance that the signal travelled. From the signal, information about the r eflector location, size, orientation and other features can sometimes be gained.

14.3. Probe types Normal Beam Probes: radiate their sound wave perpendicular to specimen surface. TR Probes: separate crystal for receiving and transmitting waves Angle Beam Probes: probes that radiate their sound wave at an angle.

14.4. Advantages 

It is sensitive to both surface and subsurface discontinuities.



The depth of penetration for flaw detection or measurement is superior to other NDT methods.



Only single-sided access is needed when the pulse-echo technique is used.



It is highly accurate in determining reflector position and estimating size and shape.

14.5. Limitations 

Surface must be accessible to transmit ultrasound.



Skill and training is more extensive than with some other methods.



It normally requires a coupling medium to promote the transfer of sound energy into the test specimen.



Materials that are rough, irregular in shape, very small, exceptionally thin or not homogeneous are difficult to inspect.



Cast iron and other coarse grained materials are difficult to inspect due to low sound transmission and high signal noise.

14.6. Magnetic Particle Testing (MPT) Magnetic particle Inspection (MPI) is an NDT process for detecting surface and slightly subsurface discontinuities in ferromagnetic materials such as i ron, nickel, cobalt, and some of their alloys. The process puts a magnetic field into the part. The piece can be magnetized by direct or indirect magnetization. Magnet ink is used as magnetic powder which is attracted to local pole sat defects. Mostly the white powdering is done on the job to increase the contrast before magnetizing.

14.7. Dye Penetrating Test (DPT) Penetrant testing (PT), is a widely applied and low-cost inspection method used to locate surface breaking defects in all non-porous materials (metals, plastics, or ceramics).

14.8. Principle DPI is based upon capillary action, where fluid having low surface tension penetrates into clean and dry surface-breaking discontinuities. Penetrant may be applied to the test component by


Chapter 14 Non-Destructive Testing

dipping, spraying, or brushing. After adequate penetration time has been allowed, the excess penetrant is removed and a developer is applied. The developer helps to draw penetrant out of the flaw so that an invisible indication becomes visible to the inspector. Inspection is performed under ultraviolet or white light, depending on the type of dye used - fluorescent or no fluorescent (visible).

14.9. Inspection steps 1. Pre-cleaning 2. Application of Penetrant 3. Excess Penetrant Removal 4. Application of Developer 5. Inspection

Mostly cleaner for the penetrant which used are solvent and water emulsifier.

14.10. Universal Crack Depth Meter X-RT-705 The crack depth meter X-RT 705 is in a fringe area of ultrasonic application. It can detect the position, depth and angle of inclination of cracks in the surfaces of metallic materials rapidly and accurately. As it operates on DC that’s why it is suitable for all the metals.

14.11. Recommendations The recommendations for the material testing facilities are: 

The testing techniques are although sufficient enough yet they are old fashioned and needed to replace by the modern techniques and equipment.



The allocation of area for the labs is not sufficient enough according to their requirement



One does not go to the dark room without permission


Chapter

15 15. Introduction For all the materials from which the jobs are to be made are subjected to some sort of testing

methods before the actual processing and working on it from raw material to t he final and finished jobs. The basic purpose of testing the material is to ensure adequate and the proper composition of elements in required percentages in the material under testing so that there will be a minimum chance of failure of job during overloading or excessive use of the job. There are two basic types of material testing methods: 



Destructive Testing Non-Destructive Testing

In destructive testing methods the forces are applied to the material until it brakes. And by the force, extension and respective values of stress and strain the qualities and properties are determined e.g. impact testing and surface hardness testing. While on the contrary the non-destructive testing includes methods which do not involve the breakage of materials. i.e. Radiography and x-ray analysis. In Qadbros the following two testing laboratories are present and working efficiently for testing of almost all type of the materials and jobs being made in Qadbeos; they are: 



Material Testing Laboratory Non Destructive Testing Laboratory

15.1. Test Performed in MTL Material testing laboratory in Qadbros is working very efficiently and it is divided in four sections according to the type and requirement of the testing methods and f or the sake of easiness and proper working separately without any inconvenience. Four sections of MTL (material testing laboratory) are following: 

Quick analysis



Chemical analysis



Metallography

Page 15-145 of 157

Chapter 15 Material Testing 

Mechanical testing

15.2. Quick analysis Quick analysis section is located in steel foundry and is further divided into two sections. One of them is testing by emission spectrometer and other is determination of composition by chemical testing methods. In spectrometer section; firstly, a sample of the molten steel is brought out in form of a cube and solidified after which it is brought into quick analysis section in which its surfaces are polished on grinders to make the surfaces shiny which is very necessary to make it balanced on the spectrometer surface otherwise the high pressure argon gas will cause any serious issues. At that time the intensity of blow holes and pores or other surface defects are also inspected visually. After this t he sample is forwarded to spectrometer room and placed below a tungsten electrode (it is used because of its highly refractory properties) and burned while the percentages of all the components or the elements of the material is obtained on a computer screen processed by a prescribed computer program. According to this result the desired percentages can be achieved by adding desired components into molten steel in case the results are not satisfactory. The same results can also be achieved by chemical testing which is to dissolve the specific mass of the material in form of the chips and then it is dissolved in respective acids for respective elements whose composition is to be determined either by titration or by formulae. But the draw backs are that this method is long, time consuming and somehow costly in terms of acids and chemical usage.

15.3. Metallography Metallography is the process which involves the testing of materials using the microscopes and other optical devices and then their internal structure is compared with the desired material’s

intermolecular structure. The important uses of the metallographic study are following: 

Process control



Presence and identity of defects



Inclusion identification and determination of their density



Examination of cracks, fractures and other failure mechanisms



Evaluation of effects of corrosion and chemical attacks



Identification of microstructure



Grain or particle size

In metallographic section we studied and observed the microstructure of grey cast iron sample which includes the graphite flakes with the simple microscope at 40 magnifications whereas its magnification is up to 450. Also we observed the structure of M.S sample by digital microscope in


Chapter 15 Material Testing

which a digital camera is placed and the photograph of the structure is obtained and its magnification is up to 5000.

15.4. Process Diagram of Metallographic Testing

Figure 15-1 Metallographic Testing

15.5. Chemical Analysis It is also a material testing facility provided by Qadbros in which almost all types of the materials are tested not only from the QADBROS but the materials of other industries are also tested here and its reports are considered satisfactory and authentic. A good trend by this laboratory is that the reports are forwarded to the respective section or shops and the tested sample is kept safely for 1 year in case of any complaint of query. The equipment possessed by this lab is: 

Furnace used to burn the samples for respective testing. Can also be called as incinerator.



Hot plate, which is electric fired



Stove, and it is also electric fired



Chemicals and acids

The basic process is the same as in quick analysis chemical section and in the lab the percentages of the elements in the materials is determined either by residual mass (percentage) of the element or by the process which includes the dissolution of chips of sample into chemicals followed by heating on hot plate or stove and then the determination of composition by titrating this solution against a standard solution.

15.6. which Materials can be tested??? As a matter of fact, the chemical analysis lab is capable of testing every kind of sample given to it but the usually it deals with the following materials mostly: 

Refractory materials like sand bricks, fire bricks, coal, fire brick li nings etc.



Babbling materials which includes copper, tin, lead and antimony i.e. nonferrous materials



Copper wires



Aluminum ingots


Chapter 15 Material Testing 

The ferrous materials include Ferro silicon and fire bricks and ferrous r ocks

15.7. Mechanical Testing The section of mechanical testing involves the destructive testing of the materials by subjecting them to various stationary and varying loads. It includes following testi ng machines: 

Impact testing machine



Hardness tester machine

15.8. Impact Testing Machine It is also a destructive test in which a sample is clamed at the bottom of the machine and a hammer of a sufficient force let say 30 tons is impacted suddenly on the sample to break it and respective readings are noted from the gauge on the machine. It is usually used for the small samples and the one used in the QADBROS mechanical testing laboratory is of 30/15 kg capacity.

15.9. Hardness Tester Hardness can be defined as the ability of a material to resist the penetration. And in the lab there are three testers used for this testing and they are: 

Rockwell Hardness Tester: used for hard materials



Brinnel Hardness Tester: used for soft materials



Vickers Hardness Test

The operation of both machines is same in which the sample in form a sphere is placed on the bed of the machine and clamped. After which the load is applied in form of a pointed rod like needle which penetrates into the sample and it is resisted by the hardness of the sample and its value is noted by the gauge indicator. •

There is also another section of the material testing laboratory called as the pyrometer section in which calibration of the gauges takes place by professional personal.


Chapter

16 16. Introduction In Assembly shop of Qadbros like other modern industries various fastening methods are used to

mechanically attach two (or more) parts together. Many products in Qadri Group are assembled largely by mechanical fastening methods; 

Sugar industry machinery



Cement Industry Parts



Paper Industry



Cranes



Power plant

In QadBros both temporary and permanent fastening methods are used.

16.1. Temporary Fastening Those that allow for disassembly e.g., Threaded fasteners like Screw, bolts and nuts

16.2. Permanent Fastening Those that create a permanent joint e.g., rivets Assembly shop is responsible for all type of assemblies generally including assembly of overheard cranes, and mobile cranes, sugar and cement plant components etc.

16.3. Assembly Assembly is a manufacturing process in which parts (usually interchangeable) are added to a product in a sequential manner to create a finished product

16.4. Why we prefer mechanical assembly? 1. Ease of assembly 2. Ease of disassembly 3. Mechanical assembly can be done by unskilled workers as compare to welding. 4. Ease of transportation 5. Easily inspected

Page 16-149 of 157

Chapter 16 Assembly Shop 6. Saves Time

Qadbros provides the facility of assembly at the site saving both time and cost of the costumer. We divide mechanical assembly methods used into following categories: 1. Threaded fasteners 2. Rivets

16.5. Threaded fasteners Threaded fasteners are discrete hardware components that have external or internal threads for assembly of parts e.g., Screw, Bolts and Nuts. In Qadbros threaded fasteners are used to assemble almost every major product. From rollers in sugar industry to boilers, cranes to road rollers, fans to metallic gates.

16.6. Screw, Bolts and Nuts Screw and bolts are threaded fasteners that have external threads. A Screw is an externally threaded fastener that is generally assembled into a blind threaded hole. A bolt is an externally threaded fastener that is inserted through holes in the parts and screwed into a nut on the opposite side. Machine screws are used for assembly into tapped holes. Cap screws are used for higher strength metals and to closer tolerances. Set screws are used for fastening collars, gears and pulleys to shafts. A self-tapping screw is used to cut or form threads in a pre-existing hole into which it is being turned. Thread fasteners in QADBROS are mainly made of steel because of its good strength and low cost. They are usually coated in Ni, Cr, Zn, and black oxide etc. for resistance to corrosion.

16.7. Washer It is a hardware component often used with threaded fasteners to ensure tightness of the mechanical joint. They 

Distribute stresses that might otherwise be concentrated at the bolt or screw head and nut



Provide support for large clearance holes in the assembled parts



Increase spring tension

16.8. Assembly Shop 

Protect part surfaces



Seal the joint



Resist inadvertent unfastening


Chapter 16 Assembly Shop

16.9. Tools and Methods for threaded fasteners Tools used varies from simple hand held Screwdrivers or wrenches to hydraulic, pneumatic or electric powered tools. Usually the pneumatic power tightening is done at the site and simple manual tightening is done at the shop

16.10. Rivets A rivet is an unthreaded, headed pin used to join two (or more) parts by passing the pin through holes in the parts and then forming (upsetting) a second head in the pin on the opposite side. The deforming operation is usually performed by hammering or steady pressing. In addition, special rivets are used for special applications. Rivets are primaril y used for lap joints. Riveting method is used as it 

Offers higher production rates



Simplicity



Dependability



Low cost

In Qadbros the tooling and methods used in riveting are 

Impact, in which pneumatic hammer delivers a succession of blows to upset the rivet.



Steady compression, in which the riveting tool applies a continuous squeezing pressure to upset the rivet



A combination of impact and compression



Equipment used was portable and manually operated.

16.11. Types of Fittings Fitting is the process of joining two mechanical parts to each other

16.12. Fits The relation between two mating parts is called fit. Depending upon the actual limits of the hole or shaft sizes, fits may be classified as clearance fit, transition fit and interference fit.

16.13. Clearance fit Clearance fit is defined as a clearance between mating parts. In clearance fit, there is always a positive clearance between the hole and shaft.

16.14. Interference fit Interference fit is obtained if the difference between the hole and shaft sizes is negative before assembly. Interference fit generally ranges from minimum to maximum interference.


Chapter 16 Assembly Shop

16.15. Transition fit Transition fit may result in either an interference or clearance, depending depending upon the actual values of the tolerance of individual parts.

16.16. Assembly Systems 16.17. Hole Basis System The size of the shaft is obtained by subtracting the allowance from the basic size of the hole. Tolerances are then applied to each part separately. In this system, the lower deviation of the hole is zero. The letter symbol indication for this is 'H'.

16.18. Shaft Basis System The upper deviation of the shaft is zero, and the size of the hole is obtained by adding the allowance to the basic size of the t he shaft. The letter symbol indication is 'h'.


Pneumatic, electric or hydraulic powered tools for fastening are not provided to workers at the shop. This reduces efficiency, effi ciency, Wastes time and decreases quality.



Hence these tools must be provided.



The bending machine is under maintenance.


Chapter

17 17. Quality Control Procedures Inspection is a process in which the material is just visually Checked by using many apparatuses

like Vernier Calliper, Micro meter screw gauges, Tapes, Compasses etc. When this is done, then a report is prepared containing all the references with respect to that the material was passed out from the inspection stage and this is a necessary step to assure the quality of the product. And is done where the status of the manufacturing industry is to be maintained and the Quality of the manufactured product product is too t oo kept up to the standards. The working process starts with agreement between purchaser and manufacture, the manufacture provides Preformat Invoice (PI) to the t he purchaser which explains the equipment specification and related price. Then the purchaser issues the Purchase Order (PO) which confirming the preformat invoice. Before start of manufacturing, the purchaser must provide equipment inspection and test plan (ITP) to the manufacture. manufacture. The ITP identifies identifies all inspection points for purchaser purchaser inspector. Then the manufacture needs to prepare the project quality control plan based of this inspection and test plan. The manufacture notifies purchaser inspector in advance to attend to her factory for witnessing the inspections and tests. The communication and coordination channel between manufacture, purchaser inspector and purchaser are agreed in the Pre-inspection meeting (PIM). Based the international practice manufacture sends her notification to the purchaser, and purchaser reviews the notification and after her approval sends to the inspector. Then the inspector will be attended in the in manufacture shop to witness the test or inspection. The purchaser inspector will send his/her inspection visit report to the purchaser. Purchaser can assign his/her own inspector which is her own direct employee or hire a third party inspection agency to carry out inspection. Inspection and test plan has tabular format and its content extracted from construction code. In each row of the table there is quality control and inspection requirement and determine which party is responsible for control and inspection. There are three parties in ITP: 1.

Manufacturer

2.

Third Party Inspector (TPI)

3.

Client or purchaser.

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Chapter 17 17 Quality Control Control Department

Final Inspection before manufacturing section consists of Pre-Inspection Meeting (PIM) and review of quality control documents which need to be approved before start of manufacturing. There are 3 or 4 important terminologies in the ITP which determines the responsibility of each party. These are:

17.1. Hold point (H) Hold on the production till TPI Inspector perform inspection and supervise the required test, as general; attendance to the PIM meeting, raw material inspection i nspection and identification, Post Weld Heat Treatment Review, Hydrostatic Test, Performance Test, Run-Out Test and Final Inspection Are Hold points. Normally manufactures shall notify TPI Inspector 7 working days in advance.

17.2. Witness Point (W) Manufacture shall notify client and TPI Inspector but there is no hold on the production, client can waive this inspection based on his discretion and inform TPI Inspector.

17.3. Spot Witness (SW) For items with spot witness wit ness manufacture shall notify TPI inspector as fulfilli ng the monitoring for example one random visit for whole UT Tests or one or two visit for whole surface preparation work for painting.

17.4. Review (R) Review means Review document, which includes includes the review of quality control records, test reports and etc. When TPI Inspector make visit for hold or witness point, the inspector can review the related documents. Rejection Cost of Group Companies in 2015-16 200 178

180 160 140 120 100 75

80

67

60 40 40 20 0

0

3

0

0.2

8 0

0

0 QBL

QCL

D&E Qty.

QE

QEN

Procurment

Millions

Graphs 17-1


Chapter 17 Quality Control Department

Rework Cost of Group Companies in 2015-16

300 260 250

200 159 150

100

50

32

27 0

0

29 0.3

0

0

4

0

0 QBL

QCL

D&E

Qty.

QE

QEN

Marketing

Millions

Graphs 17-2 Departmental Delivery Delay In 2015-16 Against Internal Commitments 1.20% 1.10%

1.00%

0.80%

0.60%

0.40%

0.20%

0.00%

0.00%

0.00%

0.00%

0.00%

Import

Procurment

QBL

D&E

QCL

0.00%

0.00% QE

QEN

Graphs 17-3


Chapter 17 Quality Control Department

Delivery Delays In 2015-16 Against Customer Delivery Dates 90 82 80 70 60 49

50 40 30 20 10 0 QadBros Engg.

Qadri Engg.

Graphs 17-4 Utilized Capcity of Group Companies in 2015-16 180000 157869

160000

140000

120000

100000

80000

60000

40000

20000 0

0

0

QBL

QCL H.F.F

QCL CUPOLA

0

0 QE

QEN

Graphs 17-5


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