Operation Window and Part-Load
Performance Study of
a Syngas Fired Gas Turbine
Sustainable Thermal Energy Management Conference 2010
a Syngas Fired Gas Turbine
Efstratios N. Pistikopoulos
Imperial College London, UK
Fen He, Zheng Li, Pei Liu, Linwei Ma,
Tsinghua University, China
November 2-3, 2010
Introduction
� With the rapid development of coal gasification, growing interest in using
syngas (mostly CO+H2) as gas turbine fuel
� Challenges to gas turbine due to fuel switch from natural gas (NG) to syngas
� to identify operation window in wide load range
� Concept of fuel dilution and air bleed/integration
N2 from
ASU
Undiluted syngas fuel
(LHV: 11~12MJ/kg) Features of dilution & air bleed
2
� Mixing of syngas with N2 (diluent) for
1. Combustion control
2. NOx control
3. Power enhancement
� Dilution increases mismatch of turbo-
machinery components
� Standard solution: air bleed for use in
ASU � GT Integration
� 25~30% integration degree requires
approximately 5~7% air bleed ratio
ASU (LHV: 11~12MJ/kg)
Diluted syngas
(LHV: 5~8MJ/kg)
Features of dilution & air bleed
Air Exhaust gas
Gas turbine model and key parameters
ASU
Fuel
Definition
Air bleedCooling air
Fuel
Compressor Variable Inlet Guide Vane
VIGV
Flame temp. TflameA general model for a typical E-class gas turbine
3
CompressorG
Air ExhaustCoolling air
Compressor outlet temp.
TK2
Surge margin
Turbine inlet temp. TIT Turbine blade temp. Tbl Exhaust temp. TAT
� Results are referred to as deviation from the baseline to facilitate the comparison
� Air bleed ratio: 0 % , 5 %, 10 %
Assumption and fuel specification
� Baseline: gas turbine with natural gas full load @ ISO ambient condition
Output (MW)
Pressure
ratio
Turbine inlet
temperature (oC)Turbine exhaust temperature (oC)
Exhaust mass flow (kg/s)
Net efficiency (%)
166.5 17.6 1100 524 533 35.7
� Fuel specification
4
No. 1
Undiluted CO-rich
No. 2Diluted CO-rich
No. 3Undiluted H2-rich
No. 4Diluted H2-rich
N2 (Vol.%) 6.22 39.65 6.23 52.08
CO2 (Vol.%) 1.01 0.65 1.13 0.58
H2O (Vol.%) 0.15 0.10 0.44 0.22
CH4 (Vol.%) 0.03 0.02 0.03 0.02
H2 (Vol.%) 30.87 19.87 87.77 44.85
CO (Vol.%) 61.72 39.72 4.40 2.25
LHV(kJ/kg) 12397 7000 42212 7000
Basic part-load control concept
Maximum TAT Temperature
5
Temperature
TAT Temperature
TAT Temperature
Baseline analysis: natural gas operationTurbine blade temperature & exhaust temperature
Close VIGV � Inlet air mass flow ↘↘↘↘� Hot gas mass flow↘↘↘↘ � Pressure ratio↘↘↘↘
-75
-50
-25
0
25
50
era
ture
[oC
]
Operation Window (natural gas)
Tblade CONSTRAIN
ISO Ambient Condition
TAT CONSTRAIN
TIT CONTROL
Coolant flow almost unchanged
↗↗↗↗
Pressure ratio↘↘↘↘ � TAT ↗↗↗↗
� Turbine outlet overheat
� Derate TIT temperature
6
0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Load
-275
-250
-225
-200
-175
-150
-125
-100
-75
Ch
ang
e in
Fla
me
Te
mp
e
40 50 60 70 80 90 100 110 120 130 140 150 160 170
Power Output [MW]
Close VIGV
max30
refTAT TAT C
°≤ +
Active operation constraints
blade,max blade,refT T≤
Coolant flow almost unchanged
� Cooling air to hot gas ratio↗↗↗↗
� Blade temperature ↘↘↘↘
-50
0
50
era
ture
[C
]
Operation Window (Natural gas, ISO condition)
TAT CO
NSTRAIN
TIT CONTROL
Tbl CONSTRAIN
15% SURGE MARGIN
1
1.2
ed P
ressure
Ratio
IGV=0IGV=5
IGV=10
IGV=20
IGV=30
GT Operation LineGT Operation Line
Baseline analysis: natural gas operationNG operation window & compressor surge margin
Gas turbine is operated along the upper boundary of the operation window.
7
-250
-200
-150
-100
Ch
an
ge
in
fla
me
te
mp
e
40 60 80 100 120 140 160
Power output [MW]
TAT
VIG
V C
LO
SE
D
VIG
V O
PE
N
TK
2 C
ON
STR
AIN
Close VIGV
0.5 0.6 0.7 0.8 0.9 1 1.1
0.6
0.8
Reduced Massflow
Com
pr.
Reduce
TIT/TAT = Constant
Surge Line
Syngas fired gas turbineDiluted CO-rich syngas without air bleed
-50
0
50
era
ture
[C
]
Operation Window (diluted syngas)LHV = 7000 kJ/kg = 7166 kJ/m3, Air bleed ratio = 0%
SURGE LINETAT CONSTRAIN
TIT CONTROL
Tbl CONSTRAIN
8% SURGE MARGIN LINE
0.9
1
1.1
1.2
1.3
d P
ressure
Ratio
IGV=0
IGV=5
IGV=10
IGV=20
IGV=30
GT Operation LineGT Operation Line
Operation window is significantly smaller due to constraints of turbine blade temp.
8
-250
-200
-150
-100
Ch
an
ge
in
fla
me
te
mp
e
80 100 120 140 160 180 200 220
Power output [MW]
VIG
V C
LO
SE
D
VIG
V O
PE
N
ONTROLTRAIN
TK
2 C
ON
ST
RA
IN0.5 0.6 0.7 0.8 0.9 1 1.1
0.4
0.5
0.6
0.7
0.8
Reduced Massflow
Com
pr.
Reduced
NG Reference
Surge Line
Impact of air bleedDiluted CO-rich syngas with air bleed
� Air bleed ratio ↗↗↗↗� Surge margin ↗↗↗↗, blade temperature ↘↘↘↘ , power↘↘↘↘
� High TAT in a wider range, benefits bottoming steam cycle
Air bleed ratio 5% Air bleed ratio 10 %
0
50
[C]
Operation Window (diluted syngas)LHV = 7000 kJ/kg = 7166 kJ/m3, Air bleed ratio = 10 %
Tbl CONSTR
15% SURGE MARGIN LINE
0
50
[C]
Operation Window (diluted syngas)LHV = 7000 kJ/kg = 7166 kJ/m3, Air bleed ratio = 5 %
8% SURGE MARGIN LINE
AINTIT
Tbl CONSTR
9
-250
-200
-150
-100
-50
Cha
ng
e in
fla
me
te
mp
era
ture
[
40 60 80 100 120 140 160 180
Power output [MW]
TAT CONSTRAIN
VIG
V C
LO
SE
D
VIG
V O
PE
N
TIT CONTROL
NSTRAIN
TK
2 C
ON
ST
RA
IN
-250
-200
-150
-100
-50
Ch
an
ge
in
fla
me
te
mp
era
ture
[
60 80 100 120 140 160 180 200
Power output [MW]
TAT CONSTRAIN
VIG
V C
LO
SE
D
VIG
V O
PE
NTIT CONTROL
NSTRAINTK
2 C
ON
STR
AIN
Impact of air bleedUndiluted CO-rich syngas
� A larger operation window is observed compared with fuel dilution
���� Less dilution benefits the gas turbine operation
� Smaller air bleed ratio is required to further improve the operation window
0
50
]
Operation Window (undiluted syngas)LHV = 12397 kJ/kg = 11137 kJ/m3, Air bleed ratio = 0%
8% SURG
E MARG
INNSTRAIN
TIT
Tbl CONSTRAIN 0
50
]
Operation Window (undiluted syngas)LHV = 12387 kJ/kg = 11137 kJ/m3, Air bleed ratio = 5 %
SURGE MARGIN
TIT CONTRO
Tbl CONSTRAIN
Air bleed ratio 0% Air bleed ratio 5%
10
-250
-200
-150
-100
-50
Ch
an
ge
in
fla
me
te
mp
era
ture
[C
]
60 80 100 120 140 160 180
Power Output [MW]
RGIN
TAT CONST
VIG
V C
LO
SE
D
VIG
V O
PE
NTIT CONTROL
AIN
TK
2 C
ON
ST
RA
IN
-250
-200
-150
-100
-50
Ch
an
ge in f
lam
e te
mp
era
ture
[C
]
40 60 80 100 120 140 160
Power output [MW]
TAT C
ONSTR
AIN
VIG
V C
LO
SE
D
VIG
V O
PE
N
TIT CONTROL
AIN
TK
2 C
ON
STR
AIN
H2-rich syngas fired gas turbineUndiluted, without air bleed
� If advanced combustion technology is available for undiluted H2-riched SG, air
bleed would not be needed.
0
50
[C
]Operation Window (undiluted H2 riched syngas)
LHV = 42212 kJ/kg = 10031 kJ/m3, Air bleed ratio = 0 %
SURGE MARGIN
IN TIT CO
Tbl CONSTRAIN
11
-250
-200
-150
-100
-50
Ch
an
ge
in
fla
me
te
mp
era
ture
60 80 100 120 140 160 180
Power output [MW]
TAT C
ONSTR
AIN
VIG
V C
LO
SE
D
VIG
V O
PE
N
TIT CONTROL
RAIN
TK
2 C
ON
STR
AIN
H2-rich syngas fired gas turbine Diluted, with & without air bleed
� The operation with diluted H2-rich syngas is more critical than CO rich syngas
� H2-content ↗↗↗↗ � Fuel heating value ↗↗↗↗ � to reach the same diluted LHV, dilution ↗↗↗↗
� hot gas mass flow ↗↗↗↗ � blade temp.↗↗↗↗ pressure ratio ↗↗↗↗� surge margin ↘↘↘↘
0
50
C]
Operation Window (diluted H2 riched syngas)LHV = 7000 kJ/kg = 5129 kJ/m3, Air bleed ratio = 0%
SURG
0
50
C]
Operation Window (diluted H2 riched syngas)LHV = 7000 kJ/kg = 5129 kJ/m3, Air bleed ratio = 5 %
8% SURGE MARGIN
Tbl CONSTRAIN
12
-250
-200
-150
-100
-50
Cha
nge
in fla
me
te
mpe
ratu
re [C
80 100 120 140 160 180 200 220 240 260
Power output [MW]
SURGE LINE
TAT CONSTRAIN
VIG
V C
LO
SE
D
VIG
V O
PE
N
TIT CONTROL
Tbl C
ONSTR
AIN
TK
2 C
ON
ST
RA
IN
-250
-200
-150
-100
-50
Ch
an
ge
in
fla
me
te
mp
era
ture
[C
60 80 100 120 140 160 180 200 220
Power output [MW]
TAT CO
NSTRAIN
VIG
V C
LO
SE
D
VIG
V O
PE
N
TIT CONTROL
TK
2 C
ON
STR
AIN
Conclusions
� Active constraints of a conventional GT fired with syngas are:
� insufficient cooling of turbine blade, and
� decreased compressor surge margin
� The lower the syngas heating value,
� the further GT operation points depart from baseline, and
� the lower the GT firing temperature
Operation with diluted H -rich syngas is more critical than with CO-rich
13
� Operation with diluted H2-rich syngas is more critical than with CO-rich syngas.
� Air bleed and less dilution are beneficial for improving GT working conditions in the current range of investigation.
Thank you for your attention! Thank you for your attention! Thank you for your attention! Thank you for your attention! Any questions?Any questions?Any questions?Any questions?
E-mail: [email protected]
