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GAS TURBINES Vivek Ghate GMS – CPP
[email protected]
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Index 1. Basics of Gas Turbines. 2. Major Components of Gas Turbines.
3. Categories of Gas Turbines. 4. Performance Comparison of various makes of Gas Turbines. 5. GE’s range of Gas Turbines.
6. Factors affecting the performance of Gas turbines. 7. Gas Turbines at RIL. 8. Maintenance factors of Gas Turbines based on the fuel used. 9. The Hot gas path components & its metallurgy. 10. Gas Turbine Control Systems. 11. Performance Benchmarking. 2 of 119
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GAS TURBINE A gas turbine, also called a combustion turbine, is a rotary engine that extracts energy from a flow of combustion gas. It has an upstream compressor coupled to a downstream turbine, and a combustion chamber in-between.
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GAS TURBINE By heating up compressed air, expanding it in nozzles mechanical/rotational energy is obtained.
Buckets
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Brayton Cycle
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Ideal Brayton cycle: • (1-2) Isentropic Compression - Ambient air is drawn into the compressor, where it is pressurized.
• (2-3) Isobaric Process - The compressed air then runs through a combustion chamber, where fuel is burned, heating that air—a constant-pressure process, since the chamber is open to flow in and out.
• (3-4) Isentropic Expansion - The heated, pressurized air then gives up its energy, expanding through a turbine (or series of turbines). Some of the work extracted by the turbine is used to drive the compressor.
• (4-1) Isobaric Process - Heat Rejection (in the atmosphere). Actual Brayton Cycle: • Adiabatic process - Compression. • Isobaric process - Heat Addition. • Adiabatic process - Expansion. • Isobaric process - Heat Rejection.
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GT Cutaway Showing Casing Cross Section
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Simple Cycle Single Shaft Gas Turbine
• Compressor & Turbine are coupled to common single shaft. • Normally used in process where less speed variation is required. • Due to larger rotor mass the speed can be easily kept constant. • Extremely suitable for generator drives. 8 of 119
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Simple Cycle Two Shaft Gas Turbine
• In 2 shaft machines turbine is divided into High Pressure (HP) turbine & Low Pressure (LP) turbine. • HP turbine & compressor are attached to one shaft & LP turbine is attached to another shaft. • These machines provide wide speed range with sufficient power & efficiency. • Well suited for mechanical drives & compressors. 9 of 119
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Open Cycle Gas Turbine Typical Performance
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Combined Cycle Power Plant
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Cogen Cycle Power Plant
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Gas Turbine Major Components
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Gas Turbine Major Components Compressor
Turbine
Combustion chamber
Starting means
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Gas Turbine Major Components COMPRESSOR • 17 stage axial flow compressor. • Extractions 5th stage: bearing cooling and sealing air. • 11th stage: Air bleed valves for surge control. • 17th stage: Atom air compressor and pulse air.
TURBINE • 3 Stage Impulse Turbine
COMBUSTION CHAMBER • 10 combustors in annular space. • 2 nos. Igniters in combustor no 1 & 10. • 4 nos. Flame scanners in the combustor no 2,3 & 7,8.
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Gas Turbine Major Components GT ANNULAR FIRING
CROSS FIRE TUBE
1&10 HAVE IGNITORS
2+3+7+8 HAVE SCANNERS
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Categories of Gas Turbines
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GAS TURBINE CATEGORIES The Simple Gas Turbine is classified into five broad groups: Frame Type Heavy - Duty Gas Turbines: Large power generation units ranging
from 3 MW to 480 MW in a simple cycle configuration. Efficiency – 30 to 39 %. Aircraft - Derivative Gas turbines: These are power generation units, which are prime mover of aircraft in the aerospace industry. Efficiency – 35 to 45%. Industrial Type - Gas Turbines: In the range of 2.5-15 MW. Used extensively for compressor drive trains. Efficiency – Less than 30%. Small Gas Turbines: In the range from about 0.5-2.5 MW. They often have centrifugal compressors & radial inflow turbines. Efficiency – 15 to 25%. Micro - Turbines: In the range from 75 - 650 kW. Efficiency – 15 to 20%.
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Frame Type Heavy - Duty Gas Turbines Gas Turbines up to 20 MW. Various Manufacturers are: Solar Turbine
Rolls Royce Siemens MHI GE
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Gas Turbine Heat Turbine Exhaust Efficiency Pressure Flow Rate Speed Temp % Ratio (kg/sec) (kcal/kwh) (rpm) (C)
MODEL
Make
Output (MW)
Saturn 20
Solar
1.2
3535
24.3
6.8
22516
6.55
504
501-KB5S Rolls Royce
3.897
2960
29.1
10.3
14200
15.4
560
SGT 100
Siemens
4.35
2865
30
13
16500
17.7
527
MF-61
MHI
5.925
3001
28.7
8.4
15400
27.3
496
Mars 100
Solar
10.69
2650
32.5
17.4
11168
42
488
LM1600PE
GE
14.898
2544
33.8
21.3
7900
49.8
479
SGT 500
Siemens
17
2671
32.2
12
3000
92.5
375
UGT15000+
Zorya Mashproek t
20
2389
36
19.4
3000
72.2
412
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Gas Turbine Gas Turbines up to 60 MW. Various Manufacturers are: Rolls Royce
Siemens Alstom IHI Mitsubishi
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Rolls Royce Gas Turbine MODEL
ISO BASE HEAT TURBINE EXHAUST EFFICIENCY PRESS FLOW YEAR RATING RATE SPEED TEMP % RATIO (kg/sec) (MW) (kcal/kwh) (rpm) (Deg C)
RB211 6761 DLE 2000
32
2188
39.3
21.5
94.55
4850
503.33
TRENT 60 DLE 1996
51
2043
42
33
151.82
3000
444.44
TRENT 60 WLE 2001
58
2104
40
36
165.91
3000
423.33
Siemens Gas Turbine MODEL
YEAR
ISO BASE RATING (MW)
HEAT RATE (kcal/kwh)
EFFICIENCY %
PRESS RATIO
FLOW (kg/sec)
TURBINE SPEED (rpm)
EXHAUST TEMP (Deg C)
SGT 700
1999
29.06
2389.72
36
18
91.36
6500
517.78
SGT 800
1998
45
2322.91
34
19.3
130.45
6600
1093.89
SGT 900
1982
49.5
2634.23
32.7
15.3
175.45
5425
513.89
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IHI Gas Turbine MODEL
ISO BASE HEAT TURBINE EXHAUST EFFICIENCY PRESS FLOW YEAR RATING RATE SPEED TEMP % RATIO (kg/sec) (MW) (kcal/kwh) (rpm) (Deg C)
LM 6000 1997 PC SPRINT
46
2123.3
40.5
30
130.45
3000
445
LM 6000 1997 PD SPRINT
45.48
2123.5
40.5
30
130.91
3000
450
Mitsubishi Gas Turbine MODEL
YEAR
MF221
1994
ISO BASE HEAT EFFICIENCY RATING RATE % (MW) (kcal/kwh)
30
2689.69
32
PRESS FLOW RATIO (kg/sec)
15
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108.18
TURBINE EXHAUST SPEED TEMP (rpm) (Deg C)
7200
532.78
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Gas Turbines more than 60 MW
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Alstom Gas Turbine ISO BASE HEAT TURBINE EXHAUST PRESS FLOW MODEL YEAR RATING RATE EFFICIENCY SPEED TEMP RATIO (kg/sec) (MW) (kcal/kwh) % (rpm) (Deg C) GT8C2
1998
56.3
2722
33.9
17
197
6219
508
GT11N2
1993
115.4
2559
33.6
16
400
3000
531
GT13E2
1993
172.2
2363
36.4
15
538
3000
522
GT26
1994
288
2246
38.3
32
633
3000
615
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Ansaldo Energia ISO BASE HEAT TURBINE EXHAUST EFFICIENCY PRESS FLOW MODEL YEAR RATING RATE SPEED TEMP % RATIO (kg/sec) (MW) (kcal/kwh) (rpm) (Deg C) V64.3A
1996
68.5
2364.51
34.7
15.8
191.4
3000
588.89
V 94.2
1981
166
2500.63
34.4
11.8
510.0
3000
546.11
V 94.3 A2
1995
272
2233.43
38.5
17.4
657.3
3000
575.00
V 94.3 A4
2004
279
2200.66
39.1
17.7
668.2
3000
577.22
Mitsubishi Gas Turbine Model
Type
ISO BASE
Eff
Heat Rate
Pressure
Flow
Turbine
Exhaust
RATING
%
(kcal/kwh)
Ratio
(kg/sec)
Speed
Temp
(rpm)
(Deg C)
(MW) M701
SC
144
34.8
2473
14
442
3000
542
M701F
CC
273+142
59
1464
17
651
3000
600
M701G
SC
334
39.5
2175
21
739
3000
587
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Siemens Gas Turbine HEAT RATE (kcal/ kwh)
EFFICIENCY %
PRESS RATIO
FLOW (kg/sec)
TURBINE SPEED (rpm)
EXHAUST TEMP (Deg C)
MODEL
YEAR
ISO BASE RATING (MW)
SGT 1000F
1996
67.7
2452.74
35.1
15.8
191.82
5400
582.78
SGT 5 2000E
1981
163.3
2496.85
34.5
11.8
528.18
3000
542.22
SGT 6 3000E
1997
188.2
2359.47
36.5
13.4
520.00
3000
581.11
SGT 6 4000F
1995
278
2199.90
39
17.2
672.27
3000
582.22
SGT 5 3000E
1997
290
1509.03
54.9 (CC)
3000
SGT 5 4000F
1995
407
1434.97
57.7 (CC)
3000
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GE’s range of Gas Turbines
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GE Heavy Duty Gas Turbine The world demands a reliable supply of clean, dependable power. GE offers a wide array of technological options to meet the most challenging energy requirements.
Model
Type
O/P (MW)
Freq (Hz)
Kcal/ kwh
MS9001H
CC
520
50
1434.3
MS9001FB
SC
412.9
50
1481.2
CC
390.8
50
1517.5
SC
255.6
50
2331.7
CC
193.2
50
1656.2
SC
126.1
50
2546.0
CC
117.7
50
1573.0
CC
75.9
50
2460.3
CC
64.3
50
1752.0
SC
42.1
50
2682.6
CC
67.2
50
1583.3
SC
45.4
50
2348.1
MS9001FA
MS9001E
MS6001FA
MS6001B
MS6001C 29 of 119
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GE H-System
First gas turbine ever to achieve the milestone of 60% fuel efficiency. 30 of 119
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S 109H 109H System Combined Cycle Power Plant 520 MW; Single shaft. Firing Temperature Class: 1430˚C (2600˚F) Heat Rate: 1435 kcal/kwh.
Efficiency: 60% 18 Stage Compressor; 23:1 Pressure Ratio; Airflow 687 kg/sec. NOx emissions: < 25 ppm. Steam Turbine: GE design; Reheat, Single flow exhaust. Generator: GE 550 MW LSTG; 660 MVA Liquid cooled. HRSG: 3 Pressure level reheat.
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The F Class Comparison GE
Siemens
Alstom
(MS9001FA)
(SGT5-4000F)
(GT26)
SIMPLE CYCLE Output
255.6 MW
278 MW
288 MW
Heat Rate
2332 kcal/kwh
2200 kcal/kwh
2246 kcal/kwh
Efficiency
36.90%
39.10%
38.3%
Pressure Ratio
17
17.2
32
Flow
642.2 kg/sec
672.2 kg/sec
633 kg/sec
Exhaust Temp.
602 Deg C
582 Deg C
615 Deg C
COMBINED CYCLE Output
390.8 MW
407 MW
410 MW
Heat Rate
1517.5 kcal/kwh
1435 kcal/kwh
1488 kcal/kwh
Efficiency
56.70%
57.70%
57.8%
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H Class Comparison GE (S109H)
Siemens (8000H)
Combined Cycle
Output Heat Rate
520 MW
530 MW
1435 kcal/kwh 1435 kcal/kwh
Efficiency
60 %
60 %
Pressure Ratio
23
19.2
Flow
687 kg/sec
820 kg/sec
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GE Aero derivative Gas Turbine
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GE Aero derivative Gas Turbine MODEL
OUTPUT (MW)
HEAT RATE (kcal/kwh)
PRESSURE RATIO
TURBINE SPEED (rpm)
FLOW (kg/sec)
EXHAUST TEMP. (C)
LMS100PA
102.998
1960.42
41.01
3000
213
407
LMS100PB
98.44
1906.48
40
3000
207
417
LM6000PC sprint
50
2132.85
31.5
3627
137
434
LM6000PC
42.89
2060.25
29.2
3627
129
436
LM6000PD sprint
46.9
2085.20
30.9
3627
132
446
LM6000PD
41.7
2110.92
29.3
3627
127
448
LM2500RC
32.91
2238.47
28.5
3600
92
524
LM2500RD
32.68
2243.76
23
3600
91
525
LM2500PH
26.46
2186.29
23
3000
76
497
GE 10 - 2
11.982
2557
15.5
11000
47
480
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Factors Affecting the Gas Turbine Performance
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Gas Turbine Performance Influences on Gas Turbine Output: Compressor Fouling
Size Influence Thermodynamic Influence Ambient condition Influence GT Speed Inlet & Exhaust Pressure Loss
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Compressor Fouling Fouling rate is a function of Environment Wind Direction Filtration System
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Size Influence Greater Dimensions
Higher Air flow
Higher Output 39 of 119
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Thermodynamic Influence Mainly determined by the design of the engine Main Component Efficiency Compressor Pressure Ratio Turbine Inlet Temperature
The combination of gas temperature and pressure ratio gives a specific output, exhaust temperature and thermal efficiency, which also are influenced by the components efficiency.
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Ambient Conditions Influence Ambient Conditions Influence Ambient Air Pressure (P0) Ambient Air Temperature (T0) Ambient Air Relative Humidity (RH)
The gas turbine nominal performance is related to: P = 1,013 bar T = 15°C RH = 60% 41 of 119
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Ambient Air Pressure (PO) At constant gas temperature INCREASED ambient air pressure gives: Increased Output Unchanged Unit Efficiency The air density reduces as the site elevation increases. While the resulting airflow and output decrease proportionately, the heat rate and other cycle parameters are not affected.
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Ambient Air Temperature (TO) The gas turbine is an air-breathing engine, its performance is changed by Air Temperature that affects the density or mass flow of the air intake to the compressor. The following graph shows effect of Ambient Air temperature on output, heat rate, heat consumption, and exhaust flow.
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Ambient Air Relative Humidity At constant gas temperature, INCREASED ambient air relative humidity gives: Decreased Output
Humid air, which is less dense than dry air, affects output and heat rate, as shown in Graph.
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GT Speed
MW
Ref: GE perf.curve GTF6SP
GT - MW change with speed at different ambient temperature range
37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20
34.95
35.4
35.7
33.3
33.6
32.25
32.55
34.35 33.75 33.15
32.7
32.4
32.1 31.5 30.75
30 28.8
26.475
26.1
25.35
24.975
24.3
23.925
23.175
28.875
28.2
27.6
26.85
30
29.4
28.65
27.975
27.225
30.45
29.85
29.1
28.35
27.6
31.05
30.975
30.3
29.625
31.65
27.75
27.15
26.4
26.7
26.025
25.65
25.35
24.6
24.3
25.575
31.5 30.45 29.4
35.925
36
36.075
36.075
33.9
34.05
34.35
32.85
33.075
34.2 33.3
32.1
32.46
31.8
32.34
31.5
30.75
31.05
31.35
30.6
30
30.3
29.7
29.325
29.55 28.65
28.65
28.2
27.6
27.15
26.55
26.1
29.025 27.975 27
28.35 27.3
33.45
27.6
24.9
23.55
22.8
22.125
95
96
97
98
99
100
101
102
103
104
105
speed % 5degC 35degC
15degC 40degC
20degC 45degC
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Inlet & Exhaust Pressure Loss Pressure Drop Effects for Frame - 6: 4 Inches H2O Inlet Drop Produces:
• 1.50% Power Output Loss • 0.50 % Heat rate Increase • 1.2 Deg F Exhaust temperature increase. 4 Inches H2O Exhaust Drop Produces:
• 0.50% Power Output Loss • 0.50 % Heat rate Increase • 1.2 Deg F Exhaust temperature increase.
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Gas Turbines with RELIANCE
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RIL Gas Turbines MODEL
Make
Output (MW)
Heat Rate (kcal/kwh)
GE 10 - 2
GE
11.982
2557
33.3
15.5
11000
47
480
Fr - 5
GE
26.30
3022
28.5
10.5
5100
123
487.2
Fr - 6
GE
37.5
2752
32.1
12.2
5100
146
544
SGT 700
SIEMENS
29.06
2390
36
18
6500
91.36
518
LM6000PC
GE
45.48
2123
40.5
30
3000
131
450
LM2500+
GE
30.057
2169
39.7
21.4
6100
84
500.5
GE
126.1
2548
33.8 (sc)
12.6
3000
418
543
GE
193.20
1656
52.0 (cc)
12.6
3000
418
543
GE
255.6
2334
36.9 (sc)
17
3000
642
602
GE
390.80
1517
56.7 (cc)
17
3000
641
602
Efficiency %
Pressure Ratio
Turbine Speed (rpm)
Flow (kg/sec)
Exhaust Temp (0C)
Fr – 9E
Fr – 9 FA
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Performance Curves for Gas Turbine
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Performance Curve for Gas Turbine
Model
Power Efficienc ISO Heat Flow consumed by y Output Rate (lb/sec) Compressor % %
Firing Temp (Deg C)
Fr – 5
26.3
3022
28.5
273
63.86
957
MS – 6541
37.5
2752
32.1
294.8
61.96
1104
Fr – 9E
126.1
2548
33.8
919.6
57.93
1124
Fr – 9FA
255.6
2334
36.9
1412.4
54.29
1327
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Gas Turbine Compressor Power NET OUTPUT (MW)
T1 T2 (C) (C)
T3 (C)
T4 WORK TURBINE COMPRESSOR WORK POWER (C) RATIO (MW) (MW)
957
%
Fr - 5
26.3
15
315
487
0.361
73
46
63.86
MS-6541
37.5
15
362 1104 544
0.380
99
61
61.96
Fr-9E
126.1
15
340 1104 543
0.421
300
174
57.93
Fr-9FA
255.6
15
407 1327 605
0.457
559
304
54.29
LM6000 PC
45.48
15
535 1260 450
0.358
127
82
64.20
SGT 700
29.06
15
416 1140 518
0.355
82
53
64.47
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40
80
30
70
20
60
10
50
0
40
MODEL
Fr - 5
MS-6541
Fr-9E
Efficiency %
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% POWER CONSUMED BY THE COMPRESSOR
EFFICIENCY, %
Effect of Power Consumed by Compressor
Fr-9FA
%
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Effect of Firing Temperature 1500
Efficiency, %
1250 30 1000 20
750 500
10 250 0 Model
Firing Temp, Deg C
40
0 Fr - 5
MS-6541
Fr – 9E
Efficiency %
Fr - 9FA
Firing Temp (Deg C)
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Comparison Model
ISO Output
Heat Rate
Efficiency %
Flow (lb/sec)
Power consumed by Compressor %
Firing Temp (Deg C)
MS-6541
37.5
2752
32.1
294.8
61.96
1104
Fr – 9FA
255.6
2334
36.9
1412.4
54.29
1327
•
For every 100 Deg F/55.5 Deg C increase in firing temperature, the efficiency increases about 1.5%. So, 223 Deg C rise in firing temp increases the efficiency by 6%. Leading to improvement in heat rate by 165 kcal/kwh.
•
7 % reduction in compressor power consumption improves the heat rate by 211 kcal/kwh.
•
Remaining 2 % improvement in Heat rate as a result of:
GTD-222 Stage 2 Nozzle
Stage – 2 & 3 Honey Comb Shrouds
86i IGV setting
Higher RPM Load Gear
High Pressure Packing Brush Seal
Improved Cooling Stage 1 Nozzle 54 of 119
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• Approximately 20% of the Inlet Air to the Axial Flow Compressor gets lost to the Thermal cycle due to losses associated with cooling hot gas path parts or losses due to Large Clearances. • Most uprates on Gas Turbines typically are achieved by Higher Airflow or Higher Firing Temperatures.
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Maintenance Factors of Gas Turbine
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Combustion System Components Efforts to advance the combustion system are driven by the need for higher firing temperatures and for compliance with regulatory requirements to reduce exhaust emissions.
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Combustion System Components Requirements: Withstanding Higher Firing Temperature. Low Emissions etc. NOx & CO. Life Time Extension. Maintenance Interval Extension.
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Factors Affecting the Combustion Components Life
Type of fuel Firing Temperature
Cyclic Effects Steam or Water Injection Quality of Air
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Maintenance factors – Hot gas path (Buckets & Nozzles)
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Fuel vs. Component life
Estimated Effect of Fuel Type on Maintenance 61 of 119
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Fuel vs. Component life Various fuels used are RFG, Naphtha, HSD& LCO .
Liquid fuel
High radiant energy Impurities (Na, K, Va)
Results 1 hr of Liquid Fuel Operation
Thermal fatigue failure Hot corrosion =
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The Firing Temperature Firing temperature
Thermal efficiency Power output
Results
1 hr of peak load operation.
Creep Distortion Reduced life = 6 hours of base load operation.
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Cyclic Effects during Start/Stop
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Cyclic Effects Each stop and start of a gas turbine subjects the hot gas path to significant thermal cycles. Control systems are designed and adjusted to minimize this effect. The severity is phenomenal in the case of emergency start and trips.
1 Emergency Trip = 8 Normal Shutdown Cycles 65 of 119
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Steam or Water Injection
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Steam or Water Injection Steam or water is injected in to the combustion system for: • NOx Reduction • Power Augmentation This steam or water Injection used causes higher dynamic pressure and due to higher specific heat capacity of steam with respect to the gas, causes higher transfer of heat to bucket and nozzle resulting in higher metal temperature of these components reducing their life.
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Hot Gas Path Components & its Metallurgy
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Combustion Liners (FR1G/FR1H) The original combustion liner was Louvered which was cooled through louvered punches in liner body (Experiencing cracking in punches during operation) Replaced with a slot-cooled liner - provides a more uniform distribution of cooling air flow for better overall cooling. Air enters the cooling holes, impinges on the brazed ring and
discharges from the internal slot as a continuous cooling film.
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The Mechanism of Slot Cooled Liner
Advantage • 139 C lower metal Temp. • Lower Temp. gradient. • Short length provide more stiffness and reduced cooling air.
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TBC Coated Liner Advantage •The 380 micron TBC thick provide 38 °C lower temp. in base metal. • For firing temp. 1124 °C the thickness of liner is 15 mil thicker.
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Transition piece Changes • The Material Hastelloy-X replaced by Nimonic 263 because of superior to creep life time. • The wall thickness is thicker and TBC coated. • T.P was lengthened 15 in to relocate the wear of Liner-T.P interface induced by compressor discharge air. • Increasing inspection interval to 12000 E.O.H. • Redesign of aft bracket allowing the T.P pivot during the thermal cycling.
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Turbine Components There have been significant design and material improvements made to the turbine components to improve component designs which can withstand higher firing temperatures due to advanced materials and coatings, as well as the addition of air cooling for some of the components.
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BUCKETS Stage 1 Bucket (FS2H) Design The original design’s sharp leading edge has been blunted to allow more cooling air to flow to the leading edge, which reduces thermal gradients and cracks.
Materials The original stage 1 bucket was IN- 738 is changed to an Equiaxed (E/A) GTD-111, a precipitation hardened, nickel-base super alloy, a greater low cycle fatigue. It also provides the industry standard in corrosion resistance.
Coatings In 1997 the coating was changed again to GT-33 INCOAT. GT-33 is a vacuum plasma spray coating, an increased resistance to through cracking. “INCOAT” refers to an aluminide coating on the cooling holes passages. 74 of 119
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BUCKETS Stage 2 Bucket (FS2F) Cooling The new stage 2 buckets contains internal air cooling ,allows for higher firing temperatures.
Tip Shroud Shroud leading edge was scalloped & tip was thickened & shroud tapered. It resulted in 25% reduction in stress and 80% increase in creep life.
Materials
Scalloping of bucket shroud
Coating GT 33 INCOAT
The original bucket was made of U-700, the material was changed to GTD-111, also a precipitation-hardened, nickelbase super alloy, to improve rupture strength. In addition it has higher low cycle fatigue strength 75 of 119
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BUCKETS Stage 3 Bucket (FS2K) Design The trailing edge was thickened, and the chord length increased, the shroud leading edge was scalloped, the shroud tip was thickened between the seal teeth, and the underside of the shroud was tapered. These design changes resulted in an increase in creep life of the bucket.
Materials The stage 3 bucket was originally made of U-500, it was changed to IN-738, a precipitation hardened, nickel-based super alloy.
Process Change A new process for the bucket which eliminates the need for the cold straightening step, thus eliminating the process induced strain in the material.
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NOZZLES Stage 2 Nozzle (FS1P)
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SHROUD BLOCKS Stage 1 Shroud Blocks (FS2C) The stage 1 shroud block was redesigned for the 2055°F/ 1124°C firing temperature. The two piece design is film cooled using airflow from the stage 2 nozzle to inhibit cracking. The film cooling required additional flow which translates into a performance loss. The main advantage of the two piece design is that it allows the damaged caps to be replaced without Having to remove the shroud block bodies or turbine nozzles. The body and hook fit are made of310 stainless steel and the cap is made of FSX-414.
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SHROUD BLOCKS Stage 2 & 3 Shroud Honey Comb Seal • i. ii. • •
Honey Comb Shroud: Reduces Leakage Greater Rub Tolerance Requires Buckets with Cutter Teeth Provides a performance improvement up to 0.6% in both output and heat rate.
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MATERIALS Turbine Blades
Turbine Nozzles
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MATERIALS Combustors
Turbine Wheels
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MATERIALS Compressor Blades
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Improvement in Firing Temperature with Blade Material
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Gas Turbine Control Systems
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RIL Gas Turbine Control System
Due to non-availability of spares, Mark IV system at RIL sites are under proposal for upgrade to Mark VI. Expected cost is Rs. 200 lacs per unit.
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GE Control System Advances System Type
Mark I
Mark II
Mark II ITS
Mark IV
Mark V
Mark VI
Introduced
1966
1973
1976
1982
1991
2004
Total Shipped
850
1825
356
1080
530
Ongoing
Sequencing
Relays
TMR Microprocessor
TMR Microprocessor
TMR Microprocessor
Control
Discrete Solid State
ICs
ICs & MPs
TMR Microprocessor
TMR Microprocessor
TMR Microprocessor
Protection
Relays
Relays & Solid State
ICs & microprocessor
TMR Microprocessor
TMR Microprocessor
TMR Microprocessor
Display
Analog Meters & Relay Annunciator
CRT & LED Aux. Display
VGA Color Graphics
VGA Color Graphics
Membrane Switches
Keyboard &/or CPD
Keyboard &/or CPD
Input
Discrete Solid State Components
Analog and Digital Meters; Solid State Annunciator
Push buttons and bat handled switches
Fault Tolerance
Manually Rejects Failed Exhaust Thermocouples
Automatic Rejects Failed T/Cs.
Hardware Based
SIFT, Software Implemented Fault Tolerance
SIFT, Software Implemented Fault Tolerance
Enhancement
Integrated Circuits
Micro-Processor
TMR & CRT Display
SIFT, VGA Graphics
Remote I/O capability
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Introduction to Control Philosophy
Control system Communicates with the turbine to Measure, adjust the parameters
It also protects the turbine from abnormal operations
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Introduction to Control Philosophy Gas Turbine Controls 1. Basic Control Parameters of GT 2. Minimum Gate Concept of Six Control Loop
Start up
Speed/Load
Temperature
Acceleration
Manual
Shut down
Main
Auxiliary
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UNIT CONTROL DISPLAY
HSD EXHAUST
BREAKER OPEN
84 dga
IGV
AIR INLET
GENERATOR
GEAR
CRANK MOTOR
WATTS VARS PF FREQ
BOX CPD 8.55 barg
NORMAL RUN STATUS SELECT2 PRESEL STATUS_FLD UNLOADING FSER_CONTROL SPEED-DROOP SPEED_LVL 14HS FLAME #A#B#C#D GT_SPEED 98.75 % TNR 102.57 % SPREAD_1 30 deg C FSR 64 % MSG_FLD1 SIMPLE CYCLE MSG_FLD2 IGV FULL OPEN SC43 AUTO SC43F NAPTHA LIQUID FUEL 100 % RT NAP/KER
Max. Vib 7.0 mm/sec
Master Control
Load Control
Fuel Select
OFF
START
BASE LOAD
GAS
CRANK
FAST START
PRESEL
HSD
STOP
MW SETPOINT
Master Select
FIRE AUTO
75
NAP
LOAD CONTROL CO-GEN
DROOP RAISE
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ISOCH
100
LOWER
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Stage Link
Controlling and Monitoring BOI Mark-V Panel
Backup operator Interface
Turbine
Generator
Station
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MARK-V CONTROL PANEL LAYOUT Station
< P>
< PD >
< QD1 >
< CD >
IONET DENET POWER STAGE LINK
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The MARK-V Control System Description
• The Mark-V control system has TMR (Triple Modular Redundant) configuration.
, and control processor. communication processor.
protective processor. power distribution processor. & input & output processor. The < I > station is used to control the turbine. The may be used to control the Turbine, whenever loss
of communication between the < I > station and Mark-V panel.
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Simple Cycle Package Power Plant Starting Time
* Time is in Minutes
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Gas Turbine Generator Controls & Limit
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Dual Fuel transfer Characteristics- Gas to Liquid
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Gas Turbine Fuel Control
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Gas Fuel Control System
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Liquid Fuel Control System
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Typical Gas Turbine Starting Characteristics
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Exhaust Temperature Control Temperature Controller ensures that the Turbine internals are protected from over heat and Optimum power is produced. The firing temperature is difficult to measure and hence the Controller uses the exhaust thermocouples as reference which is directly proportional to Firing Temperature. Tf = Tx (Pcd/Pa) k
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Exhaust/Firing Temperature Relation
Curve comparing the load
at different ambient.
The firing temperature remains constant even with increase in MW, FSR & CPR ratio with less exhaust temperatures. 101 of 119
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Acceleration Control
0.35 %/sec
0.10 %/sec 0%
40% 50% 75% 95% 100% TNH
Acceleration Control functions during sudden Load Changes and Start Up
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Manual Control
Manual Control Loop Can be used to limit fuel to prevent over firing and over riding active control.
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Shut Down Control
Shut down control loop reduces the fuel at a predetermined during shut down to reduce thermal stresses.
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IGV Control IGV Control Loop • Controls air fuel ratio • Prevents Compressor Pulsations
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IGV Control
IGV scheduling is required to ensure the protection from Pulsation/Stall by excessive opening at lower speeds/loads and negative pressures at partial loads by less opening
IGV Schedule Maintains higher Exhaust Temperature at partial loads for Combined Cycle Operation
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IGV Control Isothermal
The exhaust temp. varies for simple and combined cycle operations. IGV temperature control never exceeds the base temperature control set point.
CPD
IGV control reference Maintains higher Exhaust Temperature at partial loads for Combined Cycle Operation
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Performance Benchmarking
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Purpose of Benchmarking • Gives feed back on relative performance. • Indicating opportunities for improvement. • Un-earth and explore the outstanding Reliability issues. • Highlight the areas for improvement. • Target the initiatives for sustainable development.
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Gas Turbine Key Performance Indicators % Reliability accounting for - No. of Emergency trips - No. of Forced shutdowns - No. of Unplanned shutdowns hrs % Availability accounting for - Outage duration - MTBF Key performance indicators - Heat rate (Open cycle/Co-gen) - Efficiency (Open cycle/Co-gen) - Fuel efficiency improvement Index Fuel , Power , Steam Costs & Grid Power Bill - Percentage increase in Grid Power Consumption - Fuel, Power & Steam Cost - Fuel & Grid Power Bill 110 of 119
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Benchmarking at a Glance • Number of Emergency Trips • Number of forced shutdowns – These are numbers which indicate the number of equipment trips in each category. – RIL benchmark for not more than 1 trip/year for one equipment.
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Benchmarking at a Glance
• Number of unplanned shut down hours – This is number which indicates the number of unplanned shutdown hours in each category. – RIL has a systematic budget approach targeting planned shutdown hours for all the equipment.
– The Down time hours include planned and unplanned shutdown hours.
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Benchmarking at a Glance • GT open cycle heat rate Total direct fuel fired in GT in Kcal Power generated from GT in kwh
• GT/HRSG Co-gen Efficiency GT/HRSG Co-gen efficiency = ((A+B)/(C+D))*100 where • A= GT power generation in thermal units • B= HRSG steam generation in thermal units • C= Fuel input to GT in thermal units • D= Fuel input to HRSG supp firing in thermal units
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Benchmarking at a Glance
STG Cycle Efficiency This is the efficiency in % for STG.
STG Efficiency = (A+B/C)*100 where • A = ST power generation in thermal units • B = Steam generation in thermal units • C = Steam energy input at Steam turbine inlet in thermal units
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Benchmarking at a Glance
Auxiliary Boiler Thermal Efficiency This is the efficiency in % for Auxiliary Boiler.
Aux Boiler Efficiency = (A/B)*100 where • A = Aux boiler steam generation in thermal units • B = Fuel energy input to boilers in thermal units
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Benchmarking at a Glance
• Overall fuel utilization efficiency – This is the combined efficiency of the CPP in % – Overall Fuel utilization efficiency =((A+B+C)/(D+E+F))*100 • where • A= GT power generation in thermal units • B= ST power generation in thermal units • C= Steam extraction+PRDS steam energy in thermal units • D= GT input fuel in thermal units • E= HRSG input suppl. fuel in thermal units • F=Aux boiler input fuel in thermal units
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Benchmarking at a Glance • Fuel efficiency improvement index – This is the number in %, that indicates fuel efficiency improvement to reference period. • Fuel efficiency improvement index is then = A / B where A = Fuel efficiency for the current period B = Fuel efficiency for the reference period overall
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RIL - CPP Benchmarking Criteria Based on Key performance indicators, Ranking allotted to plants
Sr. No.
2008-’09
2007-’08
2006-’07
1 2 3 4 5 6
Jamnagar Hazira Nagothane Baroda Gandhar Patalganga
Baroda Hazira Jamnagar Nagothane Gandhar Patalganga
Patalganga Jamnagar Hazira Gandhar Baroda Nagothane
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Thank You 119 of 119
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