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LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
ASME TURBO EXPO 2001 - Land, Sea, & Air, The 46th ASME International Gas Turbine & Aeroengine Technical Congress New Orleans, Louisiana, USA, June 4-7, 2001
2001-GT-0211
EFFECTS OF ANTI-ICING SYSTEM OPERATION ON GAS TURBINE
PERFORMANCE AND MONITORING
K. Mathioudakis, A. Tsalavoutas,
Laboratory of Thermal Turbomachines National Technical University of Athens
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 2 of 22
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring
• Effects on Performance
• Impact on Monitoring
o Measurement observation
o Derived parameters
• Propose a way to improve diagnostic capability
• Present supporting data from an industrial gas turbine
• Discussion-Conclusions
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 3 of 22
Hot bleed anti-icing
Anti-icing with compressor delivery air. Compressor Bleed air
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 4 of 22
Effects of hot-bleed anti-icing on performance. Mechanisms: - air extracted from compressor delivery - compressor inlet temperature > ambient
Shift of operating line because of compressor delivery (additional) bleed.
45 50 55 60 65 70 75 80Corrected Mass Flow Rate (kg / sec)
4
6
8
10
12
14
16
Pres
sure
Rat
io
Normal ConditionIncrease of Compressor Bleed by +5%
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 5 of 22
Change of the interrelations between operating parameters.
Effect of hot bleed anti-icing operation on EGT versus load dependence.
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
50 55 60 65 70 75 80 85 90 95 100
Load %
T5-T
5nom
(oC
)
Normal operation Anti-Icing Activated
(when variation of operating parameters is monitored, their change may be misinterpreted as indication of a malfunction)
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 6 of 22
Effects On Monitored Parameters
I. Methods based on measurements observation "Signatures" of measurement deviations from nominal values are used to monitor performance and diagnose malfunctions "Signatures" can be estimated using engine models
1
41 3
2 5 4
bW
2W m
1W m
C PTCT
G
Engine subdivision into components for simulation of hot bleed anti-icing operation.
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 7 of 22
Performance Parameters Deviations,
( In function of bleed air amount)
-3
-2
-1
0
1
2
3
4
5
6
7
8
0% 1% 2% 3% 4% 5%
bleed %
diff
eren
ce %
EGT
TIT
WaN1
CDPCDT
ΔY=(Y-Yo)/Yo X 100
Differences formed for operation at the same engine inlet temperature, which is not necessarily equal to ambient temperature.
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 8 of 22
"Signature" of compressor delivery bleed, on measurements
(a) simple bleed
-0.6-0.4-0.2
00.20.40.60.8
11.21.41.6
N1 W CDP CDT Wf TIT EGT
Dev
iatio
n (%
)
(b) bleed redirected to inlet for anti-icing
-2
-1
0
1
2
3
4
N1 W CDP CDT Wf TIT EGT
Chan
ge (%
)
Constant load operation
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 9 of 22
Effects On Monitored Parameters
II. Model Based Methods Technique used "ADAPTIVE MODELLING" "HEALTH INDICES" Compressor
( ) ( )refPTWPTWf 2222221 //)/= ,
refCCf ,2 /ηη= Gas Generator Turbine
( ) ( )refPTWPTWf 4444445 ///= ,
refGGTGGTf ,6 /ηη= Power Turbine
( ) ( )ref
PTWPTWf 1.41.41.41.41.41.47 /// ⋅⋅=
refPTPTf ,8 /ηη= Measurements collected from the engine operating with the anti-icing system activated, fed to the adaptive model, without altering the layout to reflect the presence of a bleed, produce health parameters different form their nominal values.
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 10 of 22
"Signatures" of extra bleed on health indices
(different amounts of bleed )
.
-4
-2
0
2
4
6
8
10
df1 df2 df5 df6 df7
Perc
enta
ge D
evia
tions
(%)
1% 2% 3% 4% 5%
Bleed presence ≈ increase in turbines flow capacity, drop of compressor turbine efficiency.
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 11 of 22
TEST data from a gas turbine with anti-icing in operation.
.
Inlet pressure, Temperature
CDP,CDT
EGT N1
Airflow
Load
NPT
Gas turbine Layout and quantities measured for monitoring Inlet anti-icing when ambient temperature drops below 4 oCr. The amount of air designed to increase inlet temperature by approximately 5 oC
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 12 of 22
Operating conditions, including operation with anti-icing
9180
9200
9220
9240
9260
9280
9300
9320
4:00 8:00 12:00 16:00 20:00 0:00Time (hours)
N1
(rpm
)
80
85
90
95
100
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
Load
(%)
0
2
4
6
8
10
12
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
T (C
)
Tin Tamb
Anti-Icing Activation
Anti-Icing Deactivation
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 13 of 22
Effect of anti-icing operation on performance
(a) compressor related performance variables
0.95
0.96
0.97
0.98
0.99
1
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
W2
(ref
erre
d)
0.92
0.93
0.94
0.95
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
CD
P (r
efer
red)
0
2
4
6
8
10
12
14
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
CD
T-C
DT n
om
- compressor delivery temperature ↑ - compressor delivery pressure ↓ -air mass flow drops ↓ In agreement with trends predicted by the engine model
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 14 of 22
Effect of anti-icing operation on performance
(b ) exhaust gas temperature.
0
5
10
15
20
25
30
35
40
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
EGT-
EGTn
om
(c) Estimated quantities
0
5
10
15
20
25
30
35
40
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
TIT-
TIT n
om
-2
-1
0
1
4:00 8:00 12:00 16:00 20:00 0:00
Time (hours)
Δ(T
herm
al E
ffici
ency
) %
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 15 of 22
Anti-icing operation and performance parameters interrelations
EGT - Load (operation with and without anti-icing)
-10
-5
0
5
10
15
20
95 100 105
Load (%)
EGT-
EGTn
om (ο
C)
Normal
Anti-Icing
EGT gets values larger than expected for given load. Could lead to a false alarm. Turn-off the EGT checking function, when the anti-icing system is in operation.
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 16 of 22
Time evolution of health indices
(anti-icing operation no taken into account)
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df1%
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df2%
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df5%
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df6%
01234567
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df7%
Anti-icing Deactivation
Anti-icing Activation
-Flow capacity of power turbine changes by about four times the change in compressor turbine -Actual turbine problem could be overshadowed -Behavior in agreement with prediction
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 17 of 22
Accounting For Anti-Icing Operation In Monitoring
Bleed air fraction estimation Full mixing assumed
bb hWhWhW ⋅+⋅=⋅ 1122
bb WWWWWb +== 122,/
Bleed air fraction:
13
12
13
12
TTTT
hhhhb
−−
≈−−
=
-Evaluated from ambient, compressor inlet and compressor delivery temperatures -Applicable for a steady state condition
1 2
bW
2W m
1W m
C
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 18 of 22
Direct Observation Method
Measurement Changes when anti-icing is activated.
Comparison of measured to estimated values.
-2
-1
0
1
2
3
4
5
6
N1 CDP CDT EGT
Cha
nge
(%)
Measurements Predictions
Expected changes of measured quantities can be calculated from the known amount of anti-icing bleed
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 19 of 22
Time evolution of health indices
Anti-icing bleed incorporated into model.
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df1%
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df2%
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df5%
-2
-1
0
1
2
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df6
%
01234567
0:00 4:00 8:00 12:00 16:00 20:00 0:00
df7
%
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 20 of 22
Signature of -1.5 OC bias on CDT reading,
-1-0.8-0.6-0.4-0.2
00.20.40.60.8
1
f1 f2 f5 f6 f7
D (%
)
Derived by adaptive modelling the twin shaft engine
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 21 of 22
Remarks on General Applicability of Procedure A known alteration during operation should be modeled, otherwise possible incorrect conclusions
A procedure to isolate faults in the presence of altered configuration.
ADAPTIVE ENGINE MODEL
Quantities Measured for Monitoring
Inlet Conditions Setting Variables
Health indices
Engine and Component Parameters
(including bleeds)
• Effect of parameters alteration separated from effect of faults..
• Requirement for successful implementation: correct modeling.
• Other types of alteration: variable customer bleeds, VGV’s etc.
• Using an adapted engine model gives an additional advantage: § data for unmeasured quantities (e.g. TIT), § additional information on overall performance (e.g thermal efficiency)
LABORATORY OF THERMAL TURBOMACHINES NATIONAL TECHNICAL UNIVERSITY OF ATHENS
Effects Of Anti-Icing System Operation On Gas Turbine Performance And Monitoring 01-021
Page 22 of 22
Summary - Conclusions
• Effects of hot bleed anti-icing on the performance of
an industrial gas turbine examined • Behavior of different performance variables can be
predicted using an engine performance model • Influence of anti-icing operation on monitoring
procedures analyzed. Uunless appropriate provisions are taken, difficulties may be introduced to the diagnosis and false alarms are possible
• A method to eliminate such possible shortcomings was
introduced: information for altered configuration introduced into a supporting engine model
• Data from an industrial gas turbine, used to
substantiate observations
• Generality of such an approach discussed. Approach useful for other types of altered configuration.