A Training report On “TURBINE MANUFACTURING” At
BHEL HARIDWAR Submitted in partial fulfillment of requirements for the degree of
Bachelor of Technology In Mechanical Engineering
Submitted By: ABHINAV BARTHWAL B.Tech. (Final Year)
Submitted To: MOHD.YUNUS SHEIKH Sr. Lecturer
Department of Mechanical Engineering GOVT. ENGINEERING COLLEGE, BIKANER RAJASTHAN TECHNICAL UNIVERSITY, KOTA 2012-13
ACKNOWLEDGEMENT
“Inspiration and motivation have always played a key role in the success of any venture.” Success in such comprehensive report can’t be achieved single handed. It is the team effort that sail the ship to the coast. So I would like to express my sincere thanks to my mentor MR. A.K. KHUSHWAHA Sir. I am also grateful to the management of Bharat Heavy Electrical limited (BHEL), Haridwar for permitting me to have training during June 2th to July 2th, 2012. It gives me in immense pleasure to express my gratitude to the department of Mechanical Engineering for their prudent response in course of completing my training report. I am highly indebted to, MR. MOHD. YOUNIS SHEIKH, their guidance and whole hearted inspiration; it has been of greatest help in bringing out the work in the present shape. The direction, advice, discussion and constant encouragement given by them has been so help full in completing the work successfully
[i]
INDEX
S.R. NO.
TOPIC
PAGE NO.
INTRODUCTION
1.
1
BHEL
2 – 17
1.1.OVERVIEW
2
1.2.WORKING AREAS
3
1.2.1 POWER GENERATION
3
1.2.2 POWER TRANSMISSION &DISTRIBUTION
3
1.2.3 INDUSTRIES
4
1.2.4 TRANSPORTATION
5
1.2.5 TELECOMMUNICATION
5
1.2.6 RENEWABLE ENERGY
5
1.2.7 INTERNATIONAL OPERATIONS
6
1.3 TECHNOLOGY UP GRADATION AND RESEARCH AND DEVELOPMENT 1.3.1HUMAN RESOURCE DEVELOPMENT INSTITUTE
7
1.4 HEALTH, SAFETY AND ENVIRONMENT MANAGEMENT 1.4.1 ENVIRONMENTAL POLICY
8
1.4.2 OCCUPATIONAL HEALTH AND SAFETY POLICY
8
1.4.3 PRINCIPLES OF THE "GLOBAL COMPACT"
9
1.5 BHEL UNITS
11
1.6 BHEL HARIDWAR
13
1.6.1LOCATION
13
1.6.2ADDRESS
13
1.6.3 AREA
13
1.6.4 UNITS
14
1.6.5 HEEP PRODUCT PROFILE
16
[ii]
7
8
2.
3.
4.
5.
6.
STEAM TURBINE
18-21
2.1 INTRODUCTION
18
2.2 ADVANTAGES
20
2.3DISADVANTAGES
21
2.4 STEAM TURBINES THE MAINSTAY OF BHEL
21
TYPES OF STEAM TURBINE
22-23
3.1 IMPULSE TURBINE
22
3.2 THE IMPULSE TURBINE PRINCIPLE
22
3.3 REACTION PRINCIPLE
23
3.4 IMPULSE TURBINE STAGING
23
TURBINE PARTS
24-25
4.1 TURBINE BLADES
24
4.2 TURBINE CASING
24
4.3 TURBINE ROTORS
25
CONSTRUCTIONAL FEATURES OF A BLADE
26-33
5.1 H.P. BLADE PROFILE
26
5.2 CLASSIFICATION OF PROFILES
27
5.3 H.P BLADE ROOTS
28
5.4 L.P BLADE PROFILE
30
5.5 L.P BLADE ROOTS
30
5.6 DYNAMICS IN BLADE
30
5.7 BLADING MATERIALS
33
MANUFACTURING PROCESS
34-37
6.1 INTRODUCTION
34
6.2 CLASSIFICATION OF MANUFACTURING PROCESS 6.2.1 PRIMARY SHAPING PROCESSES
34
[iii]
35
6.2.2 SECONDAY OR MACHINING PROCESSES
36
7.
BLOCK-3 LAY-OUT
38
8.
CLASSIFICATION OF BLOCK-3
39-42
9.
BLADE SHOP
43-45
10.
9.1 TYPES OF BLADES
43
9.2 OPERATIONS PERFORMED ON BLADES
44
9.3 MACHINING OF BLADES
44
9.4 NEW BLADE SHOP
45
CONCLUSION
46
[iv]
FIGURE INDEX
S.R.NO.
TOPIC
PAGE NO.
1.
SECTIONAL VIEW OF A STEAM TURBINE
18
2.
FLOW DIAGRAM OF A STEAM TURBINE
19
3.
HIGH PRESSURE BLADE PROFILE
26
4.
OVERSPEED AND VACCUM BALANCING TUNNEL
40
5.
STEAM TURBINE CASING AND ROTORS IN ASSEMBLING
42
AREA 6.
CNC ROTOR TURNING LATHE
42
7.
TYPES OF BLADES
43
8.
SCHEMATIC DIAGRAM OF A CNC MACHINE
44
9.
CNC SHAPING MACHINE
45
[v]
TABLE INDEX
S.R.NO.
TOPIC
PAGE NO.
1.
BHEL UNITS
12
2.
BLOCKS IN HEEP
14
3.
SECTIONS IN CFFP
15
4.
BLADE ROOTS
29
5.
LAYOUT OF BLOCK-3
38
[vi]
INTRODUCTION BHEL is the largest engineering and manufacturing enterprise in India in the energy related infrastructure sector today. BHEL was established more than 40 years ago when its first plant was setup in Bhopal ushering in the indigenous Heavy Electrical Equipment Industry in India a dream which has been more than realized with a well recognized track record of performance it has been earning profits continuously since 1971-72. BHEL caters to core sectors of the Indian Economy viz., Power Generation's & Transmission, Industry, Transportation, Telecommunication, Renewable Energy, Defense, etc. The wide network of BHEL's 14 manufacturing division, four power Sector regional centers, over 150 project sites, eight service centers and 18 regional offices, enables the Company to promptly serve its customers and provide them with suitable products, systems and services – efficiently and at competitive prices. BHEL has already attained ISO 9000 certification for quality management, and ISO 14001 certification for environment management. The company’s inherent potential coupled with its strong performance make this one of the “NAVRATNAS”, which is supported by the government in their endeavor to become future global players.
1
1. BHEL 1.1. OVERVIEW Bharat Heavy Electricals Limited (B.H.E.L.) is the largest engineering and manufacturing enterprise in India. BHEL caters to core sectors of the Indian Economy viz., Power Generation's & Transmission, Industry, Transportation, Telecommunication, Renewable Energy, Defense and many more. Established in 1960s under the Indo-Soviet Agreements of 1959 and 1960 in the area of Scientific, Technical and Industrial Cooperation. BHEL has its setup spread all over India namely New Delhi, Gurgaon, Haridwar, Rudrapur, Jhansi, Bhopal, Hyderabad, Jagdishpur , Tiruchirapalli, Bangalore and many more. Over 65% of power generated in India comes from BHEL-supplied equipment. Overall it has installed power equipment for over 90,000 MW. BHEL's Investment in R&D is amongst the largest in the corporate sector in India. Net Profit of the company in the year 2011-2012 was recorded as 6868 crore having a high of 21.2% in comparison to last year. BHEL has already attained ISO 9000 certification for quality management, and ISO 14001 certification for environment management. It is one of India's nine largest Public Sector Undertakings or PSUs, known as the NAVRATNAS or 'the nine jewels' The power plant equipment manufactured by BHEL is based on contemporary technology comparable to the best in the world The wide network of BHEL's 14 manufacturing divisions, four Power Sector regional centre, over 100 project sites, eight service centre and 18 regional offices, enables the Company to promptly serve its customers and provide them with suitable products, systems and services – efficiently 2
1.2. WORKING AREAS 1.2.1. POWER GENERATION Power generation sector comprises thermal, gas, hydro and nuclear power plant business as of 31.03.2001, BHEL supplied sets account for nearly 64737 MW or 65% of the total installed capacity of 99,146 MW in the country, as against nil till 1969-70. BHEL has proven turnkey capabilities for executing power projects from concept to commissioning, it possesses the technology and capability to produce thermal sets with super critical parameters up to 1000 MW unit rating and gas turbine generator sets of up to 240 MW unit rating. Co-generation and combined-cycle plants have been introduced to achieve higher plant efficiencies. to make efficient use of the high-ash-content coal available in India, BHEL supplies circulating fluidized bed combustion boilers to both thermal and combined cycle power plants. The company manufactures 235 MW nuclear turbine generator sets and has commenced production of 500 MW nuclear turbine generator sets. Custom made hydro sets of Francis, Pelton and Kaplan types for different head discharge combination are also engineering and manufactured by BHEL. In all, orders for more than 700 utility sets of thermal, hydro, gas and nuclear have been placed on the Company as on date. The power plant equipment manufactured by BHEL is based on contemporary technology comparable to the best in the world and is also internationally competitive. The Company has proven expertise in Plant Performance Improvement through renovation modernization and upgrading of a variety of power plant equipment besides specialized know how of residual life assessment, health diagnostics and life extension of plants. 1.2.2. POWER TRANSMISSION & DISTRIBUTION (T & D) BHEL offer wide ranging products and systems for T & D applications. Products manufactured
include
power
transformers,
instrument
transformers,
dry type 3
transformers, series – and stunt reactor, capacitor tanks, vacuum – and SF circuit breakers gas insulated switch gears and insulators. A strong engineering base enables the Company to undertake turnkey delivery of electric substances up to 400 kV level series compensation systems (for increasing power transfer capacity of transmission lines and improving system stability and voltage regulation), shunt compensation systems (for power factor and voltage improvement) and HVDC systems (for economic transfer of bulk power). BHEL has indigenously developed the state-of-the-art controlled shunt reactor (for reactive power management on long transmission lines). Presently a 400 kV Facts (Flexible AC Transmission System) project under execution. 1.2.3. INDUSTRIES BHEL is a major contributor of equipment and systems to industries. Cement, sugar, fertilizer, refineries, petrochemicals, paper, oil and gas, metallurgical and other process industries lines and improving system stability and voltage regulation, shunt compensation systems (for power factor and voltage improvement) and HVDC systems (for economic transfer of bulk power) BHEL has indigenously developed the state-of-theart controlled shunt reactor (for reactive power management on long transmission lines). Presently a 400 kV FACTS (Flexible AC Transmission System) projects is under execution. The range of system & equipment supplied includes: captive power plants, cogeneration plants DG power plants, industrial steam turbines, industrial boilers and auxiliaries. Water heat recovery boilers, gas turbines, heat exchangers and pressure vessels, centrifugal compressors, electrical machines, pumps, valves, seamless steel tubes, electrostatic precipitators, fabric filters, reactors, fluidized bed combustion boilers, chemical recovery boilers and process controls. The Company is a major producer of large-size thruster devices. It also supplies digital distributed control systems for process industries, and control & instrumentation systems for power plant and industrial applications. BHEL is the only company in India with the capability to make simulators for power plants, defense and other applications.
4
The Company has commenced manufacture of large desalination plants to help augment the supply of drinking water to people. 1.2.4. TRANSPORTATION BHEL is involved in the development design, engineering, marketing, production, installation, maintenance and after-sales service of Rolling Stock and traction propulsion systems. In the area of rolling stock, BHEL manufactures electric locomotives up to 5000 HP, diesel-electric locomotives from 350 HP to 3100 HP, both for mainline and shunting duly applications. BHEL is also producing rolling stock for special applications viz., overhead equipment cars, Special well wagons, Rail-cum-road vehicle etc., Besides traction propulsion systems for in-house use, BHEL manufactures traction propulsion systems for other rolling stock producers of electric locomotives, diesel-electric locomotives, electrical multiple units and metro cars. The electric and diesel traction equipment on India Railways are largely powered by electrical propulsion systems produced by BHEL. The company also undertakes retooling and overhauling of rolling stock in the area of urban transportation systems. BHEL is geared up to turnkey execution of electric trolley bus systems, light rail systems etc. BHEL is also diversifying in the area of port handing equipment and pipelines transportation system. 1.2.5. TELECOMMUNICATION BHEL also caters to Telecommunication sector by way of small, medium and large switching systems. 1.2.6. RENEWABLE ENERGY Technologies that can be offered by BHEL for exploiting non-conventional and renewable sources of energy include: wind electric generators, solar photovoltaic systems, solar lanterns and battery-powered road vehicles. The Company has taken up R&D efforts for development of multi-junction amorphous silicon solar cells and fuel based systems.
5
1.2.7. INTERNATIONAL OPERATIONS BHEL has, over the years, established its references in around 60 countries of the world, ranging for the United States in the west to New Zealand in the far east. these references encompass almost the entire product range of BHEL, covering turnkey power projects of thermal, hydro
and gas-based types, substation projects, rehabilitation
projects, besides a wide variety of products, like transformers, insulators, switchgears, heat exchangers, castings and forgings, valves, well-head equipment, centrifugal compressors, photo-voltaic equipment etc. apart from over 1110mw of boiler capacity contributed in Malaysia, and execution of four prestigious power projects in Oman, some of the other major successes achieved by the company have been in Australia, Saudi Arabia, Libya, Greece, Cyprus, Malta, Egypt, Bangladesh, Azerbaijan, Sri Lanka, Iraq etc. The company has been successful in meeting demanding customer's requirements in terms of complexity of the works as well as technological, quality and other requirements viz. extended warrantees, associated O&M, financing packages etc. BHEL has proved its capability to undertake projects on fast-track basis. The company has been successful in meeting varying needs of the industry, be it captive power plants, utility power generation or for the oil sector requirements. Executing of overseas projects has also provided BHEL the experience of working with world renowned consulting organizations and inspection agencies. In addition to demonstrated capability to undertake turnkey projects on its own, BHEL possesses the requisite flexibility to interface and complement with international companies for large projects by supplying complementary equipment and meeting their production needs for intermediate as well as finished products. The success in the area of rehabilitation and life extension of power projects has established BHEL as a comparable alternative to the original equipment manufacturers (OEM’S) for such plants.
6
1.3. TECHNOLOGY UPGRADATION AND RESEARCH & DEVELOPMENT To remain competitive and meet customers' expectations, BHEL lays great emphasis on the continuous up gradation of products and related technologies, and development of new products. The Company has upgraded its products to contemporary levels through continuous in house efforts as well as through acquisition of new technologies from leading engineering organizations of the world. The Corporate R&D Division at Hyderabad, spread over a 140 acre complex, leads BHEL's research efforts in a number of areas of importance to BHEL's product range. Research and product development centers at each of the manufacturing divisions play a complementary role. BHEL's Investment in R&D is amongst the largest in the corporate sector in India. Products developed in-house during the last five years contributed about 8.6% to the revenues in 2000-2001. BHEL has introduced, in the recent past, several state-of-the-art products developed in-house: low-NOx oil / gas burners, circulating fluidized bed combustion boilers, high-efficiency Pelton hydro turbines, petroleum depot automation systems, 36 kV gas-insulated sub-stations, etc. The Company has also transferred a few technologies developed in-house to other Indian companies for commercialization. Some of the on-going development & demonstration projects include: Smart wall blowing system for cleaning boiler soot deposits, and micro-controller based governor for diesel-electric locomotives. The company is also engaged in research in futuristic areas, such as application of super conducting materials in power generations and industry, and fuel cells for distributed, environment-friendly power generation. 1.3.1 HUMAN RESOURCE DEVELOPMENT INSTITUTE The most prized asset of BHEL is its employees. The Human Resource Development Institute and other HRD centers of the Company help in not only keeping their skills updated and finely honed but also in adding new skills, whenever required. Continuous training and retraining, positive, a positive work culture and participative 7
style of management, have engendered development of a committed and motivated work force leading to enhanced productivity and higher levels of quality. 1.4. HEALTH, SAFETY AND ENVIRONMENT MANAGEMENT BHEL, as an integral part of business performance and in its endeavor of becoming a world-class organization and sharing the growing global concern on issues related to Environment. Occupational Health and Safety, is committed to protecting Environment in and around its own establishment, and to providing safe and healthy working environment to all its employees. For fulfilling these obligations, Corporate Policies have been formulated as: 1.4.1. ENVIRONMENTAL POLICY Compliance with applicable Environmental Legislation/Regulation; Continual Improvement in Environment Management Systems to protect our natural environment and Control Pollution; Promotion of activities for conservation of resources by Environmental Management; Enhancement of Environmental awareness amongst employees, customers and suppliers. BHEL will also assist and co-operate with the concerned Government Agencies and Regulatory Bodies engaged in environmental activities, offering the Company's capabilities is this field. 1.4.2. OCCUPATIONAL HEALTH AND SAFETY POLICY Compliance with applicable Legislation and Regulations; Setting objectives and targets to eliminate/control/minimize risks due to Occupational and Safety Hazards; Appropriate structured training of employees on Occupational Health and Safety (OH&S) aspects;
8
Formulation and maintenance of OH&S Management programs for continual improvement; Periodic review of OH&S Management System to ensure its continuing suitability, adequacy and effectiveness; Communication of OH&S Policy to all employees and interested parties. The major units of BHEL have already acquired ISO 14001 Environmental Management System Certification, and other units are in advanced stages of acquiring the same. Action plan has been prepared to acquire OHSAS 18001 Occupational Health and Safety Management System certification for all BHEL units. In pursuit of these Policy requirements, BHEL will continuously strive to improve work particles in the light of advances made in technology and new understandings in Occupational Health, Safety and Environmental Science. Participation in the "Global Compact" of the United Nations. The "Global Compact" is a partnership between the United Nations, the business community, international labor and NGOs. It provides a forum for them to work together and improve corporate practices through co-operation rather than confrontation. BHEL has joined the "Global Compact" of United Nations and has committed to support it and the set of core values enshrined in its nine principles: 1.4.3. PRINCIPLES OF THE "GLOBAL COMPACT" HUMAN RIGHTS 1. Business should support and respect the protection of internationally proclaimed human rights; and 2. Make sure they are not complicit in human rights abuses.
9
LABOUR STANDARDS 3. Business should uphold the freedom of association and the effective recognition of the right to collective bargaining; 4. The elimination of all form of forces and compulsory labor. 5. The effective abolition of child labor, and 6. Eliminate discrimination. ENVIRONMENT 7. Businesses should support a precautionary approach to environmental challenges; 8. Undertake initiatives to promote greater environmental responsibility and 9. Encourage the development
and diffusion of environmentally friendly
technologies. By joining the "Global Compact", BHEL would get a unique opportunity of networking with corporate and sharing experience relating to social responsibility on global basis.
10
1.5. BHEL UNITS UNIT 1. Bhopal
TYPE Heavy Electrical Plant
PRODUCT Steam turbines , Turbo generators , Hydro sets , Switch gear controllers
2. Haridwar HEEP CFFP
Heavy Electrical
Hydro turbines , Steam turbines, Gas
Equipment Plant
turbine, Turbo generators, Heavy castings
Central Foundry Forge Plant
and forging. Control panels, Light aircrafts, Electrical machines
3.Hyderabad HPEP
Heavy Power Equipment
Industrial turbo – sets, Compressors Pumps
Plant
and heaters, Bow mills, Heat exchangers oil rings, Gas turbines , Switch gears, Power generating set
4.Tiruchi HPBP SSTP
High Pressure Boiling
Steam less steel tubes, Spiral fin welded
Plant
tubes.
5.Jhansi TP
Transformer Plant
Transformers, Diesel shunt less AC locos and AC EMU
11
6.Banglore EDN EPD
Control Equipment
Energy meters, Water meters , Control
Division
equipment, Capacitors , Photovoltaic panels, Electro Porcelain Division
Simulator , Telecommunication system, Other advanced micro processor based control system. Insulator and bushing, Ceramic liners.
7.Ranipet BAP
Electrostatic precipitator, Air pre-heater,
Boiler Auxiliaries Plant
Fans, Wind electric generators, Desalination plants. 8.Goindwal
Industrial Valves Plant
Industrial valves and Fabrication
Insulator Plant.
High tension ceramic, Insulation Plates and
9.Jagdishpur IP
bushings 10.Rudrapur
Component Fabrication
Windmill, Solar water heating system
Plant 11.Gurgoan
Amorphous Silicon Solar
Solar Photovoltaic Cells, Solar lanterns
Cell Plant.
chargers , Solar clocks
TABLE1
12
1.6. BHEL HARIDWAR 1.6.1. LOCATION It is situated in the foot hills of Shivalik range in Haridwar. The main administrative building is at a distance of about 8 km from Haridwar. 1.6.2. ADDRESS Bharat Heavy Electrical Limited (BHEL) Ranipur, Haridwar PIN:- 249403 1.6.3. AREA BHEL Haridwar consists of two manufacturing units, namely Heavy Electrical Equipment Plant (HEEP) and Central Foundry Forge Plant (CFFP), having area HEEP area:- 8.45 sq km CFFP area:- 1.0 sq km The Heavy Electricals Equipment Plant (HEEP) located in Haridwar, is one of the major manufacturing plants of BHEL. The core business of HEEP includes design and manufacture of large steam and gas turbines, turbo generators, hydro turbines and generators, large AC/DC motors and so on. Central Foundry Forge Plant (CFFP) is engaged in manufacture of Steel Castings: Up to 50 Tons per Piece Wt & Steel Forgings: Up to 55 Tons per Piece Wt. 1.6.4. UNITS There are two units in BHEL Haridwar as followed: 1) Heavy Electrical Equipment Plant (HEEP) 2) Central Foundry Forge Plant (CFFP). 13
THERE ARE 8 BLOCKS IN HEEP
BLOCKS
WORK PERFORMED IN THE BLOCK
I. Electrical Machine
Turbo generator, generator exciter , motor (ac and dc)
II. Fabrication
Large size fabricated assemblies or components
III. Turbine & Auxiliary
Steam ,hydro ,gas turbines, turbine blade , special tooling
IV. Feeder
Winding of Turbo ,hydro generators ,insulation for ac & dc motors
V. Fabrication
Fabricated parts of steam turbine, water boxes, storage tank, hydro turbine parts
VI. Fabrication Stamping and die
Fabricated oil tanks, hollow guide blades, Rings, stator frames and rotor spindle, all dies, stamping for generators
and
motors
manufacturing
14
VII. Wood working
Wooden packing, spacers.
VIII. Heaters & coolers
LP heaters, ejectors, glands, steam and oil coolers, Oil tank, bearing covers
TABLE 2
THERE ARE 3 SECTIONS IN CFFP
SECTIONS
WORK PERFORMED IN THE SECTION
I.
Foundry
Casting of turbine rotor, casing and Francis runner
II.
Forging
Forging of small rotor parts
III. Machine shop
Turning, boring, parting off, drilling etc.
TABLE 3
15
1.6.5. HEEP PRODUCT PROFILE
1. THERMAL SETS: Steam turbines and generators up to 500 MW capacity for utility and combined cycle applications Capability to manufacture up to 1000 MW unit cycle.
2. GAS TURBINES: Gas turbines for industry and utility application; range-3 to 200 MW (ISO). Gas turbines based co-generation and combined cycle system .
3. HYDRO SETS: Custom– built conventional hydro turbine of Kaplan, Francis and Pelton with matching generators up to 250 MW unit size. Pump turbines with matching motor-generators. Mini / micro hydro sets. Spherical butterfly and rotary valves and auxiliaries for hydro station.
4. EQUIPMENT FOR NUCLEAR POWER PLANTS: Turbines and generators up to 500MW unit size. Steam generator up to 500MW unit size. Re-heaters / separators. Heat exchangers and pressure vessels.
5. ELECTRICAL MACHINES: DC general purpose and rolling mill machines from 100 to 19000KW suitable for operation on voltage up to 1200V. These are provided with STDP, totally enclosed and duct ventilated enclosures. DC auxiliary mill motors.
16
6. CONTROL PANEL: Control panel for voltage up to 400KW and control desks for generating stations and EMV sub–stations.
7. CASTING AND FORGINGS: Sophisticated heavy casting and forging of creep resistant alloy steels, stainless steel and other grades of alloy meeting stringent international specifications.
8. DEFENCE: Naval guns with collaboration of Italy.
17
2. STEAM TURBINE
2.1 INTRODUCTION A turbine is a device that converts chemical energy into mechanical energy, specifically when a rotor of multiple blades or vanes is driven by the movement of a fluid or gas. In the case of a steam turbine, the pressure and flow of newly condensed steam rapidly turns the rotor. This movement is possible because the water to steam conversion results in a rapidly expanding gas. As the turbine’s rotor turns, the rotating shaft can work to accomplish numerous applications, often electricity generation.
FIG.1 SECTIONAL VIEW OF A STEAM TURBINE In a steam turbine, the steam’s energy is extracted through the turbine and the steam leaves the turbine at a lower energy state. High pressure and temperature fluid at the inlet of the turbine exit as lower pressure and temperature fluid. The difference is energy converted by the turbine to mechanical rotational energy, less any aerodynamic and mechanical inefficiencies incurred in the process. Since the fluid is at a lower pressure at the exit of the turbine than at the inlet, it is common to say the fluid has been “expanded” across the turbine. Because of the expanding flow, higher volumetric flow 18
occurs at the turbine exit (at least for compressible fluids) leading to the need for larger turbine exit areas than at the inlet. The generic symbol for a turbine used in a flow diagram is shown in Figure below. The symbol diverges with a larger area at the exit than at the inlet. This is how one can tell a turbine symbol from a compressor symbol. In Figure , the graphic is colored to indicate the general trend of temperature drop through a turbine. In a turbine with a high inlet pressure, the turbine blades convert this pressure energy into velocity or kinetic energy, which causes the blades to rotate. Many green cycles use a turbine in this fashion, although the inlet conditions may not be the same as for a conventional high pressure and temperature steam turbine. Bottoming cycles, for instance, extract fluid energy that is at a lower pressure and temperature than a turbine in a conventional power plant. A bottoming cycle might be used to extract energy from the exhaust gases of a large diesel engine, but the fluid in a bottoming cycle still has sufficient energy to be extracted across a turbine, with the energy converted into rotational energy.
FIG.2 FLOW DIAGRAM OF A STEAM TURBINE Turbines also extract energy in fluid flow where the pressure is not high but where the fluid has sufficient fluid kinetic energy. The classic example is a wind turbine, which converts the wind’s kinetic energy to rotational energy. This type of kinetic energy conversion is common in green energy cycles for applications ranging from larger wind turbines to smaller hydrokinetic turbines currently being designed for and demonstrated in river and tidal applications. Turbines can be designed to work well in a variety of fluids, including gases and liquids, where they are used not only to drive generators, but also to drive compressors or pumps. 19
One common (and somewhat misleading) use of the word “turbine” is “gas turbine,” as in a gas turbine engine. A gas turbine engine is more than just a turbine and typically includes a compressor, combustor and turbine combined to be a self-contained unit used to provide shaft or thrust power. The turbine component inside the gas turbine still provides power, but a compressor and combustor are required to make a selfcontained system that needs only the fuel to burn in the combustor. An additional use for turbines in industrial applications that may also be applicable in some green energy systems is to cool a fluid. As previously mentioned, when a turbine extracts energy from a fluid, the fluid temperature is reduced. Some industries, such as the gas processing industry, use turbines as sources of refrigeration, dropping the temperature of the gas going through the turbine. In other words, the primary purpose of the turbine is to reduce the temperature of the working fluid as opposed to providing power. Generally speaking, the higher the pressure ratio across a turbine, the greater the expansion and the greater the temperature drop. Even where turbines are used to cool fluids, the turbines still produce power and must be connected to a power absorbing device that is part of an overall system. Also note that turbines in high inlet-pressure applications are sometimes called expanders. The terms “turbine” and “expander” can be used interchangeably for most applications, but expander is not used when referring to kinetic energy applications, as the fluid does not go through significant expansion.
2.2. ADVANTAGES:Ability to utilize high pressure and high temperature steam. High efficiency. High rotational speed. High capacity/weight ratio. Smooth, nearly vibration-free operation. No internal lubrication. Oil free exhausts steam. 20
2.3 DISADVANTAGES:For slow speed application reduction gears are required. The steam turbine cannot be made reversible. The efficiency of small simple steam turbines is poor.
2.4 STEAM TURBINES THE MAINSTAY OF BHEL BHEL has the capability to design, manufacture and commission steam turbines of up to 1000 MW rating for steam parameters ranging from 30 bars to 300 bars pressure and initial & reheat temperatures up to 600 ºC. Turbines are built on the building block system, consisting of modules suitable for a range of output and steam parameters. For a desired output and steam parameters appropriate turbine blocks can be selected.
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3. TYPES OF STEAM TURBINE There are complicated methods to properly harness steam power that give rise to the two primary turbine designs: impulse and reaction turbines. These different designs engage the steam in a different method so as to turn the rotor 3.1 IMPULSE TURBINE The principle of the impulse steam turbine consists of a casing containing stationary steam nozzles and a rotor with moving or rotating buckets. The steam passes through the stationary nozzles and is directed at high velocity against rotor buckets causing the rotor to rotate at high speed. The following events take place in the nozzles: 1. The steam pressure decreases. 2. The enthalpy of the steam decreases. 3. The steam velocity increases. 4. The volume of the steam increases. 5. There is a conversion of heat energy to kinetic energy as the heat energy from the decrease in steam enthalpy is converted into kinetic energy by the increased steam velocity. 3.2 THE IMPULSE PRINCIPLE If steam at high pressure is allowed to expand through stationary nozzles, the result will be a drop in the steam pressure and an increase in steam velocity. In fact, the steam will issue from the nozzle in the form of a high-speed jet. If this high steam is applied to a properly shaped turbine blade, it will change in direction due to the shape of the blade. The effect of this change in direction of the steam flow will be to produce an impulse force, on the blade causing it to move. If the blade is attached to the rotor of a turbine, then the rotor will revolve. Force applied to the blade is developed by causing the steam to change direction of flow (Newton’s 2nd Law – change of momentum). The change of momentum produces the impulse force. The fact that the pressure does not drop across the moving blades is the distinguishing feature of the impulse turbine. The 22
pressure at the inlet to the moving blades is the same as the pressure at the outlet from the moving blades. 3.3 REACTION PRINCIPLE A reaction turbine has rows of fixed blades alternating with rows of moving blades. The steam expands first in the stationary or fixed blades where it gains some velocity as it drops in pressure. It then enters the moving blades where its direction of flow is changed thus producing an impulse force on the moving blades. In addition, however, the steam upon passing through the moving blades again expands and further drops in pressure giving a reaction force to the blades. This sequence is repeated as the steam passes through additional rows of fixed and moving blades. 3.4 IMPULSE TURBINE STAGING In order for the steam to give up all its kinetic energy to the moving blades in an impulse turbine, it should leave the blades at zero absolute velocity. This condition will exist if the blade velocity is equal to one half of the steam velocity. Therefore, for good efficiency the blade velocity should be about one half of steam velocity. In order to reduce steam velocity and blade velocity, the following methods may be used: 1. Pressure compounding. 2. Velocity compounding. 3. Pressure-velocity compounding. 4. Pressure Compounding
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4. TURBINE PARTS 4.1 TURBINE BLADES Cylindrical reaction blades for HP, IP and LP Turbines 3-DS blades, in initial stages of HP and IP Turbine, to reduce secondary losses. Twisted blade with integral shroud, in last stages of HP, IP and initial stages of LP turbines, to reduce profile and Tip leakage losses o Free standing LP moving blades Tip sections with supersonic design o
Fir-tree root
o
Flame hardening of the leading edge
Banana type hollow guide blade o Tapered and forward leaning for optimized mass flow distribution o Suction slits for moisture removal 4.2 TURBINE CASING Casings or cylinders are of the horizontal split type. This is not ideal, as the heavy flanges of the joints are slow to follow the temperature changes of the cylinder walls. However, for assembling and inspection purposes there is no other solution. The casing is heavy in order to withstand the high pressures and temperatures. It is general practice to let the thickness of walls and flanges decrease from inlet- to exhaust-end. The casing joints are made steam tight, without the use of gaskets, by matching the flange faces very exactly and very smoothly. The bolt holes in the flanges are drilled for smoothly fitting bolts, but dowel pins are often added to secure exact alignment of the flange joint. Double casings are used for very high steam pressures. The high pressure is applied to the inner casing, which is open at the exhaust end, letting the turbine exhaust to the outer casings.
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4.3 TURBINE ROTORS The design of a turbine rotor depends on the operating principle of the turbine. The impulse turbine with pressure drop across the stationary blades must have seals between stationary blades and the rotor. The smaller the sealing area, the smaller the leakage; therefore the stationary blades are mounted in diaphragms with labyrinth seals around the shaft. This construction requires a disc rotor. Basically there are two types of rotor: DISC ROTORS All larger disc rotors are now machined out of a solid forging of nickel steel; this should give the strongest rotor and a fully balanced rotor. It is rather expensive, as the weight of the final rotor is approximately 50% of the initial forging. Older or smaller disc rotors have shaft and discs made in separate pieces with the discs shrunk on the shaft. The bore of the discs is made 0.1% smaller in diameter than the shaft. The discs are then heated until they easily are slid along the shaft and located in the correct position on the shaft and shaft key. A small clearance between the discs prevents thermal stress in the shaft. DRUM ROTORS The first reaction turbines had solid forged drum rotors. They were strong, generally well balanced as they were machined over the total surface. With the increasing size of turbines the solid rotors got too heavy pieces. For good balance the drum must be machined both outside and inside and the drum must be open at one end. The second part of the rotor is the drum end cover with shaft.
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5. CONSTRUCTIONAL FEATURES OF A BLADE
The blade can be divided into 3 parts: The profile, which converts the thermal energy of steam into kinetic energy, with a certain efficiency depending upon the profile shape. The root, which fixes the blade to the turbine rotor, giving a proper anchor to the blade, and transmitting the kinetic energy of the blade to the rotor. The damping element, which reduces the vibrations which necessarily occur in the blades due to the steam flowing through the blades. These damping elements may be integral with blades, or they may be separate elements mounted between the blades. Each of these elements will be separately dealt with in the following sections. 5.1 H.P. BLADE PROFILES In order to understand the further explanation, a familiarity of the terminology used is required. The following terminology is used in the subsequent sections. CAMBER
LINE
CHORD BITANGENT LINE
FIG.3 HIGH PRESSURE BLADE PROFILE
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If circles are drawn tangential to the suction side and pressure side profiles of a blade, and their centers are joined by a curve, this curve is called the camber line. This camber line intersects the profile at two points A and B. The line joining these points is called chord, and the length of this line is called the chord length. A line which is tangential to the inlet and outlet edges is called the bitangent line. The angle which this line makes with the circumferential direction is called the setting angle. Pitch of a blade is the circumferential distance between any point on the profile and an identical point on the next blade.
5.2 CLASSIFICATION OF PROFILES There are two basic types of profiles - Impulse and Reaction. In the impulse type of profiles, the entire heat drop of the stage occurs only in the stationary blades. In the reaction type of blades, the heat drop of the stage is distributed almost equally between the guide and moving blades. Though the theoretical impulse blades have zero pressure drop in the moving blades, practically, for the flow to take place across the moving blades, there must be a small pressure drop across the moving blades also. Therefore, the impulse stages in practice have a small degree of reaction. These stages are therefore more accurately, though less widely, described as low-reaction stages. The presently used reaction profiles are more efficient than the impulse profiles at part loads. This is because of the more rounded inlet edge for reaction profiles. Due to this, even if the inlet angle of the steam is not tangential to the pressure-side profile of the blade, the losses are low. However, the impulse profiles have one advantage. The impulse profiles can take a large heat drop across a single stage, and the same heat drop would require a greater number of stages if reaction profiles are used, thereby increasing the turbine length.
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The Steam turbines use the impulse profiles for the control stage (1st stage), and the reaction profiles for subsequent stages. There are three reasons for using impulse profile for the first stage.
a) Most of the turbines are partial arc admission turbines. If the first stage is a reaction stage, the lower half of the moving blades do not have any inlet steam, and would ventilate. Therefore, most of the stage heat drop should occur in the guide blades. b) The heat drop across the first stage should be high, so that the wheel chamber of the outer casing is not exposed to the high inlet parameters. In case of -4 turbines, the inner casing parting plane strength becomes the limitation, and therefore requires a large heat drop across the 1st stage. c) Nozzle control gives better efficiency at part loads than throttle control. d) The number of stages in the turbine should not be too high, as this will increase the length of the turbine.
There are exceptions to the rule. Turbines used for CCPs, and BFP drive turbines do not have a control stage. They are throttle-governed machines. Such designs are used when the inlet pressure slides. Such machines only have reaction stages. However, the inlet passages of such turbines must be so designed that the inlet steam to the first reaction stage is properly mixed, and occupies the entire 360 degrees. There are also cases of controlled extraction turbines where the L.P. control stage is an impulse stage. This is either to reduce the number of stages to make the turbine short, or to increase the part load efficiency by using nozzle control, which minimizes throttle losses. 5.3 H.P. BLADE ROOTS The root is a part of the blade that fixes the blade to the rotor or stator. Its design depends upon the centrifugal and steam bending forces of the blade. It should be designed such that the material in the blade root as well as the rotor / stator claw and any fixing element are in the safe limits to avoid failure. The roots are T-root and Fork-root. The fork root has a higher load-carrying capacity than the T-root. It was found that 28
machining this T-root with side grip is more of a problem. It has to be machined by broaching, and the broaching machine available could not handle the sizes of the root. The typical roots used for the HP moving blades for various steam turbine applications are shown in the following figure:
T-ROOT
T-ROOT WITH SIDE GRIP
FORK ROOT
TABLE 4 BLADE ROOTS
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5.4 L.P. BLADE PROFILES The LP blade profiles of moving blades are twisted and tapered. These blades are used when blade height-to-mean stage diameter ratio (h/Dm) exceeds 0.2.
5.5 LP BLADE ROOTS The roots of LP blades are as follows: 1) 2 blading : The roots of both the LP stages in –2 type of LP blading are T-roots. 2) 3 blading: The last stage LP blade of HK, SK and LK blades have a fork-root. SK blades have 4-fork roots for all sizes. HK blades have 4-fork roots up to 56 size, where modified profiles are used. Beyond this size, HK blades have 3 fork roots. LK blades have 3-fork roots for all sizes. The roots of the LP blades of preceding stages are of T-roots.
5.6 DYNAMICS IN BLADE
The excitation of any blade comes from different sources. They are: a) Nozzle-passing excitation: As the blades pass the nozzles of the stage, they encounter flow disturbances due to the pressure variations across the guide blade passage. They also encounter disturbances due to the wakes and eddies in the flow path. These are sufficient to cause excitation in the moving blades. The excitation gets repeated at every pitch of the blade. This is called nozzle-passing frequency excitation. The order of this frequency = no. of guide blades x speed of the machine. Multiples of this frequency are considered for checking for resonance.
b) Excitation due to non-uniformities in guide-blades around the periphery. These can occur due to manufacturing inaccuracies, like pitch errors, setting angle variations, inlet and outlet edge variations, etc.
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For HP blades, due to the thick and cylindrical cross-sections and short blade heights, the natural frequencies are very high. Nozzle-passing frequencies are therefore necessarily considered, since resonance with the lower natural frequencies occurs only with these orders of excitation. In LP blades, since the blades are thin and long, the natural frequencies are low. The excitation frequencies to be considered are therefore the first few multiples of speed, since the nozzle-passing frequencies only give resonance with very high modes, where the vibration stresses are low.
The HP moving blades experience relatively low vibration amplitudes due to their thicker sections and shorter heights. They also have integral shrouds. These shrouds of adjacent blades butt against each other forming a continuous ring. This ring serves two purposes – it acts as a steam seal, and it acts as a damper for the vibrations. When vibrations occur, the vibration energy is dissipated as friction between shrouds of adjacent blades.
For HP guide blades of Wesel design, the shroud is not integral, but a shroud band is riveted to a number of guide blades together. The function of this shroud band is mainly to seat the steam. In some designs HP guide blades may have integral shrouds like moving blades. The primary function remains steam sealing.
In industrial turbines, in LP blades, the resonant vibrations have high amplitudes due to the thin sections of the blades, and the large lengths. It may also not always be possible to avoid resonance at all operating conditions. This is because of two reasons. Firstly, the LP blades are standardized for certain ranges of speeds, and turbines may be selected to operate anywhere in the speed range. The entire design range of operating speed of the LP blades cannot be outside the resonance range. It is, of course, possible to design a new LP blade for each application, but this involves a lot of design efforts and manufacturing cycle time. However, with the present-day computer packages and manufacturing methods, it has become feasible to do so. Secondly, the driven machine may be a variable speed machine like a compressor or a boiler-feed-pump. In this case 31
also, it is not possible to avoid resonance. In such cases, where it is not possible to avoid resonance, a damping element is to be used in the LP blades to reduce the dynamic stresses, so that the blades can operate continuously under resonance also. There may be blades which are not adequately damped due to manufacturing inaccuracies. The need for a damping element is therefore eliminated. In case the frequencies of the blades tend towards resonance due to manufacturing inaccuracies, tuning is to be done on the blades to correct the frequency. This tuning is done by grinding off material at the tip (which reduces the inertia more than the stiffness) to increase the frequency, and by grinding off material at the base of the profile (which reduces the stiffness more than the inertia) to reduce the natural frequency.
The damping in any blade can be of any of the following types: a) Material damping: This type of damping is because of the inherent damping properties of the material which makes up the component. b) Aerodynamic damping: This is due to the damping of the fluid which surrounds the component in operation. c) Friction damping: This is due to the rubbing friction between the component under consideration with any other object. Out of these damping mechanisms, the material and aerodynamic types of damping are very small in magnitude. Friction damping is enormous as compared to the other two types of damping. Because of this reason, the damping elements in blades generally incorporate a feature by which the vibrational energy is dissipated as frictional heat. The frictional damping has a particular characteristic. When the frictional force between the rubbing surfaces is very small as compared to the excitation force, the surfaces slip, resulting in friction damping. However, when the excitation force is small when compared to the frictional force, the surfaces do not slip, resulting in locking of the surfaces. This condition gives zero friction damping, and only the material and aerodynamic damping exists. In a periodically varying excitation force, it may frequently happen that the force is less than the friction force. During this phase, the damping is very 32
less. At the same time, due to the locking of the rubbing surfaces, the overall stiffness increases and the natural frequency shifts drastically away from the individual value. The response therefore also changes in the locked condition. The resonant response of a system therefore depends upon the amount of damping in the system (which is determined by the relative duration of slip and stick in the system, i.e., the relative magnitude of excitation and friction forces) and the natural frequency of the system (which alters between the individual values and the locked condition value, depending upon the slip or stick condition).
5.7 BLADING MATERIALS
Among the different materials typically used for blading are 403 stainless steel, 422 stainless steel, A-286, and Haynes Stellite Alloy Number 31 and titanium alloy. The 403 stainless steel is essentially the industry’s standard blade material and, on impulse steam turbines, it is probably found on over 90 percent of all the stages. It is used because of its high yield strength, endurance limit, ductility, toughness, erosion and corrosion resistance, and damping. It is used within a Brinell hardness range of 207 to 248 to maximize its damping and corrosion resistance. The 422 stainless steel material is applied only on high temperature stages (between 700 and 900°F or 371 and 482°C), where its higher yield, endurance, creep and rupture strengths are needed.
The A-286 material is a nickel-based super alloy that is generally used in hot gas expanders with stage temperatures between 900 and 1150°F (482 and 621°C). The Haynes Stellite Alloy Number 31 is a cobalt-based super alloy and is used on jet expanders when precision cast blades are needed. The Haynes Stellite Number 31 is used at stage temperatures between 900 and 1200°F (482 and 649°C). Another blade material is titanium. Its high strength, low density, and good erosion resistance make it a good candidate for high speed or long-last stage blading.
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6. MANUFACTURING PROCESS 6.1 INTRODUCTION Manufacturing process is that part of the production process which is directly concerned with the change of form or dimensions of the part being produced. It does not include the transportation, handling or storage of parts, as they are not directly concerned with the changes into the form or dimensions of the part produced. Manufacturing is the backbone of any industrialized nation. Manufacturing and technical staff in industry must know the various manufacturing processes, materials being processed, tools and equipments for manufacturing different components or products with optimal process plan using proper precautions and specified safety rules to avoid accidents. Beside above, all kinds of the future engineers must know the basic requirements of workshop activities in term of man, machine, material, methods, money and other infrastructure facilities needed to be positioned properly for optimal shop layouts or plant layout and other support services effectively adjusted or located in the industry or plant within a well planned manufacturing organization. Today’s competitive manufacturing era of high industrial development and research, is being called the age of mechanization, automation and computer integrated manufacturing. Due to new researches in the manufacturing field, the advancement has come to this extent that every different aspect of this technology has become a fullfledged fundamental and advanced study in itself. This has led to introduction of optimized design and manufacturing of new products. New developments in manufacturing areas are deciding to transfer more skill to the machines for considerably reduction of manual labor. 6.2 CLASSIFICATION OF MANUFACTURING PROCESSES For producing of products materials are needed. It is therefore important to know the characteristics of the available engineering materials. Raw materials used manufacturing of products, tools, machines and equipments in factories or industries are for providing commercial castings, called ingots. Such ingots are then processed in 34
rolling mills to obtain market form of material supply in form of bloom, billets, slabs and rods. These forms of material supply are further subjected to various manufacturing processes for getting usable metal products of different shapes and sizes in various manufacturing shops. All these processes used in manufacturing concern for changing the ingots into usable products may be classified into six major groups as Primary shaping processes Secondary machining processes Metal forming processes Joining processes Surface finishing processes and Processes effecting change in properties
6.2.1 PRIMARY SHAPING PROCESSES Primary shaping processes are manufacturing of a product from an amorphous material. Some processes produces finish products or articles into its usual form whereas others do not, and require further working to finish component to the desired shape and size. The parts produced through these processes may or may not require to undergo further operations. Some of the important primary shaping processes are: (1) Casting (2) Powder metallurgy (3) Plastic technology (4) Gas cutting (5) Bending and (6) Forging.
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6.2.2 SECONDARY OR MACHINING PROCESSES As large number of components require further processing after the primary processes. These components are subjected to one or more number of machining operations in machine shops, to obtain the desired shape and dimensional accuracy on flat and cylindrical jobs. Thus, the jobs undergoing these operations are the roughly finished products received through primary shaping processes. The process of removing the undesired or unwanted material from the work-piece or job or component to produce a required shape using a cutting tool is known as machining. This can be done by a manual process or by using a machine called machine tool (traditional machines namely lathe, milling machine, drilling, shaper, planner, slotter). In many cases these operations are performed on rods, bars and flat surfaces in machine shops. These secondary processes are mainly required for achieving dimensional accuracy and a very high degree of surface finish. The secondary processes require the use of one or more machine tools, various single or multi-point cutting tools (cutters), job holding devices, marking and measuring instruments, testing devices and gauges etc. for getting desired dimensional control and required degree of surface finish on the workpieces. The example of parts produced by machining processes includes hand tools machine tools instruments, automobile parts, nuts, bolts and gears etc. Lot of material is wasted as scrap in the secondary or machining process. Some of the common secondary or machining processes are: Turning Threading Knurling Milling Drilling Boring Planning Shaping Slotting Sawing 36
Broaching Hobbing Grinding Gear Cutting Thread cutting and Unconventional machining processes namely machining with Numerical control (NC) machines tools or Computer Numerical Control(CNC) machine tool using ECM, LBM, AJM, USM setups.
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7. BLOCK 3 LAY-OUT
TABLE5 LAYOUT OF BLOCK-3
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8. CLASSIFICATION
OF BLOCK 3
BAY-1 IS FURTHER DIVIDED INTO THREE PARTS 1. HMS In this shop heavy machine work is done with the help of different NC & CNC machines such as center lathes, vertical and horizontal boring & milling machines. Asia’s largest vertical boring machine is installed here and
CNC
horizontal boring
milling
machines
from Skoda of
Czechoslovakia.
2. Assembly Section (of hydro turbines) – In this section assembly of hydro turbines are done. Blades of turbine are 1st assemble on the rotor & after it this rotor is transported to balancing tunnel where the balancing is done. After balancing the rotor, rotor & casings both internal & external are transported to the customer. Total assembly of turbine is done in the company which purchased it by B.H.E.L.
3. OSBT (over speed balancing tunnel)In this section, rotors of all type of turbines like LP(low pressure), HP(high pressure)& IP(Intermediate pressure) rotors of Steam turbine , rotors of Gas & Hydro turbine are balanced .In a large tunnel, Vacuum of 2 torr is created with the help of pumps & after that rotor is placed on pedestal and rotted with speed of 2500-4500 rpm. After it in a computer control room the axis of rotation of rotor is seen with help of computer & then balance the rotor by inserting the small balancing weight in the grooves cut on rotor.
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FIG.4 OVERSPEED AND VACCUM BALANCING TUNNEL For balancing and over speed testing of rotors up to 320 tons in weight, 1800 mm in length and 6900 mm diameter under vacuum conditions of 1 Torr BAY –2 IS DIVIDED IN TO 2 PARTS: 1. HMS– In this shop several components of steam turbine like LP, HP & IP rotors, Internal & external casing are manufactured with the help of different operations carried out through different NC & CNC machines like grinding, drilling, vertical & horizontal milling and boring machines, center lathes, planer, Kopp milling machine. 2 .Assembly section– In this section assembly of steam turbines up to 1000 MW Is assembled. 1st moving blades are inserted in the grooves cut on circumferences of rotor, then rotor is balanced in balancing tunnel in bay-1. After is done in which guide blades are assembled inside the internal casing &
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then rotor is fitted inside this casing. After it this internal casing with rotor is inserted into the external.
BAY 3 IS DIVIDED INTO 3 PARTS: 1. Bearing section – In this section Journal bearings are manufactured which are used in turbines to overcome the vibration & rolling friction by providing the proper lubrication. 2. Turning section – In this section small lathe machines, milling & boring machines, grinding machines & drilling machines are installed. In this section small jobs are manufactured like rings, studs, disks etc. 3. Governing section – In this section governors are manufactured. These governors are used in turbines for controlling the speed of rotor within the certain limits. 1st all components of governor are made by different operations then these all parts are treated in heat treatment shop for providing the hardness. Then these all components are assembled into casing. There are more than 1000 components of Governor.
BAY-4 IS DIVIDED INTO 3 PARTS: 1. TBM (turbine blade manufacturing) shop- In this shop solid blade of both steam & gas turbine are manufactured. Several CNC & NC machines are installed here such as Copying machine, Grinding machine, Rhomboid milling machine, Duplex milling machine, T- root machine center, Horizontal tooling center, Vertical & horizontal boring machine etc.
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FIG.5 STEAM TURBINE CASING AND ROTORS IN ASSEMBLY AREA 2. Turning section- Same as the turning section in Bay-3, there are several small Machine like lathes machines, milling, boring, grinding machines etc.
FIG.6 CNC ROTOR TURNING LATHE Heat treatment shopIn this section there are several tests performed for checking the hardness of different components. Tests performed are Sterelliting, Nitriding, DP test.
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9. BLADE SHOP Blade shop is an important shop of Block 3. Blades of all the stages of turbine are made in this shop only. They have a variety of centre lathe and CNC machines to perform the complete operation of blades. The designs of the blades are sent to the shop and the Respective job is distributed to the operators. Operators perform their job in a fixed interval of time. 9.1 TYPES OF BLADES Basically the design of blades is classified according to the stages of turbine. The size of LP TURBINE BLADES is generally greater than that of HP TURBINE BLADES. At the first T1, T2, T3 & T4 kinds of blades were used, these were 2nd generation blades. Then it was replaced by TX, BDS (for HP TURBINE) & F shaped blades. The most modern blades are F & Z shaped blades.
FIG.7 TYPES OF BLADES
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9.2 OPERATIONS PERFORMED ON BLADES Some of the important operations performed on blade manufacturing are:Milling Blank Cutting Grinding of both the surfaces Cutting Root milling
9.3 MACHINING OF BLADES Machining of blades is done with the help of Lathe & CNC machines. Some of the machines are:Centre lathe machine Vertical Boring machine Vertical Milling machine CNC lathe machine
FIG.8 SCHEMATIC DIAGRAM OF A CNC MACHINE
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9.4 NEW BLADE SHOP A new blade shop is being in operation, mostly 500mw turbine blades are manufactured in this shop. This is a highly hi tech shop where complete manufacturing of blades is done using single advanced CNC machines. Complete blades are finished using modernized CNC machines. Some of the machines are:Pama CNC ram boring machine Wotum horizontal machine with 6 axis CNC control CNC shaping machine
FIG.9 CNC SHAPING MACHINE
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10. CONCLUSION Gone through rigorous one month training under the guidance of capable engineers and workers of BHEL Haridwar in Block-3 “TURBINE MANUFACTURING” headed by Senior Engineer of department Mr. A.K. KHUSHWAHA situated in Ranipur, Haridwar, Uttarakhand. The training was specified under the Turbine Manufacturing Department. Working under the department I came to know about the basic grinding, scaling and machining processes which was shown on heavy to medium machines. Duty lathes were planted in the same line where the specified work was undertaken. The training brought to my knowledge the various machining and fabrication processes went not only in the manufacturing of blades but other parts of the turbine.
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