g GSSA TAs TECHNICAL SUPPORT

TECHNICAL DOCUMENTs

Gas Turbine Typical Start-Up Curves

The documents TTS_xx_yyy are produced by "GSSA TA's Technical Support".

The relevant instructions must be apply by GSSA engineers or under their direct supervision.

TTS_OI_304
Jan-05
REV. 0
PAGE 1 OF 15
The gas turbine operate as per Bryton cycle: the air goes into axial compressor (see point "1") at ambient conditions. These conditions
are relating to ambient pressure, temperature and humidity. The standard design data are classified as ISO CONDITION with reference
to the following values:

Ambient Temperature: 15 °C
Ambient Pressure: 1013 mBar
Relative Humidity: 60 %

Subsequently, the air is compressed by the axial compressor and come out as per point "2" conditions. During this phase the heat
increase to a certain value (depending of a turbine model) because of the polytrophic type compression. After the compression, the air
goes into combustion chambers at the same pressure and temperature condition of point "2". The fuel is inject into combustion chamber
and the combustion is realized at constant pressure. Next to the burner, the local temperature can reach more than 2000°C: too high for
the resistance of downstream material. Therefore the final temperature, due to transformation in point "3", is lower because of the result
of the mixed gas of primary combustion with the cooling air. The temperature of point "3" is the maximum temperature of the cycle and
called "firing temperature".

FIRING TEMPERATURE
The "A" section is defined as "Turbine inlet temperature"; this is the medium temperature of the gas in the "A" plane.
The "B" section is defined as "Firing Temperature"; this is the medium temperature of the gas in the "B" plane.
The "C" section is defined as "Firing Temperature at ISO"; this is the medium temperature of the gas in the "C" plane,
calculated as a function of flow and fuel by means of thermal combustion balance as per ISO 2314.
The interpretation difference between section "A" and "B" gas turbine temperature, is because on "B" section we
consider also the air cooling coming from first stage nozzle witch is not a part of the combustion but is going to be mix
with the exhaust gas just after the cool down of the same nozzle. As per "Nuovo Pignone- G.E. standard th
temperature of point "3" is the same as temperature of "B" section.
The next step is from point "3" to point "4". It is the gas expansion through turbine section, witch convert the thermal
energy to kinetic energy. This energy, through the the shaft rotation, is used for the axial compressor work (internal use
and not available for operating machines) and for external utilities (by means of load coupling)
More than 50% of the developed energy is absorb by the compression done by axial compressor.
Downstream section "4" the exhaust gas are released to the atmosphere (see picture below where P is pressure, V is
volume, T is temperature and S is entropy.

The compression work (Wc) from point "1" to "2" is given (approximately) from the
following relation:

The expansion work (Wt) from point "3" to "4" is given from the following relation:

The heat (Q1) supply to the combustion chamber from point "2" to "3" is given by th
following formula:

The turbine cycle is going to "close" from point "4" to point "1": that is the cool down of exhaust
gas, by means of loosing heat (Q2) because of the atmosphere:
The thermodynamic relation which describe the cool-down of the exhaust gas is the following:

The Cpm values is the specific heating (at constant pressure) between the temperature limits of
the considered gap.

The thermodynamic efficiency is given by the formula:

That means, with the same heating value Q1 injected into combustion chamber, the efficiency
increase when the heat Q2 dissipated to the atmosphere, decrease.

The Work (Nu) given to the driven machine is:

where Ggas and Gair are respectively the weight of flow measured in the turbine inle
and in the compressor air suction.
Fuel Stroke Reference Control
 Control System Schematic

Combustion System Speed Control

Fuel Gas Valve Schematic System

Gas Fuel Control System

Gas Control Valve Schematic Diagram

 Protective System Summary

Protective System Schematic

Vibration Protection Schematic Flame Detection System

Overtemperature Protection
 LM 2500 DLE TYPICAL START-UP CURVE

= XNGG XNPT=

10000 6500

7700 rpm

Staging valve N°11

L14 LS
LP
HP
rpm
rpm
3250

L28FDX Flame detected Axial compr. discharge temp. (T3) 265°C

Pilot Valve

Crank Speed Inner Valve

2000

Outer Valve

Purge Time Accelerate End Of Sequence (L14 LS)

Start the unit

- Reach crank speed (20% XNGG)
- Wait for purge time
- End of purge time: Staging valve N°11 (or N°4 depending of the side of spark plug) will be energized; Pilot valve
will open approximately 9% and Outer valve will open approximately 4% in order to make the ignition easier;
it will shut after approximately 13 sec. (if flame has been detect)
- Acceleration to XNPT minimum load (XNPT speed control); VSV will move according with T2 and XNGG speed
- Unit ready to load (bleed valve will move according with mapping schedule, see next page)
- Temperature control is detect by T54 thermocouple located on GG exhaust.

GG ACCELERATION RATE = 50 rpm/Sec

 LM 2500 DLE TYPICAL START-UP CURVE

= XNGG XNPT=

6000

Idle speed
6800
4000

4400
Ignition 2000

Crank speed
2000

= VSV BLEED=
Max. Bleed
VSV close

VSV open
Min. Bleed
 LM 6000PD DLE TYPICAL START-UP CURVE

14000

12000

10000
XN25 - RPM

8000

6000

4000

2000

0
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

TIME - MINUTES
 H.D. GAS TURBINE TYPICAL START-UP CURVE (GENERAL)

0,35 %/Sec
0,31 %/Sec (FR7; FR6)
0,10 %/Sec
L14HS (Antisurge valve close)

0,35 %/Sec
0,31 %/Sec (FR7; FR6)

0,13 %/Sec
0,11 %/Sec (FR7; FR6)

0,11 %/Sec

Start the unit

- Reach crank speed
- Wait for purge time
- Ignition
- Warm-up time
- Acceleration to minimum load (FSR control: start-up control / acceleration control / speed control)
- I.G.V. will move according with speed and exhaust temperature; typically I.G.V. will move to Min. position (56 DEG), then will open in order to keep exhaust temperature to a fix value
(371°C for MS 5002)
- At 60% the starting motor will cut-off
- Once L14HS is energized (usually 95% of TNH) the anti-surge valve will shut
 MS 5001 TYPICAL START-UP CURVE

= TTXM
I.G.V. =
= HP speed

440 °C

5100

L28FDX Flame detected 85

4845
272 °C
HP I.G.V.
rpm 247 °C (DEG)
Axial Compr. Antisurge
Valve Command 56

42
1020

Purge Time Antisurge close command

Full Speed No Load

Firing & Warm-up Accelerate

Start the unit

- Reach crank speed (20% of TNH)
- Wait for purge time
- Ignition
- Warm-up time
- Acceleration to Full Speed No Load (FSR control: Start-Up control / Acceleration control / Speed control). Refer to previous page for
acceleration constants value
- I.G.V. will move according with speed and exhaust temperature
- At 60% the starting motor will cut-off
- Once L14 HS speed relay is energized (Normally at 95% of TNH), the anti-surge valve will shut
- Once the Full Speed No Load status (100% of TNH) has been reach, the unit is ready to operate.
 MS 5002 TYPICAL START-UP CURVE

= TTXM LP speed =
= HP speed I.G.V. =
4670
5100 L14 HS

4845
Axial Compr. Antisurge
Valve Command
L28FDX Flame detected
415°C
L14 LS
3035
HP 370°C
rpm LP
rpm
330°C

56 DEG

Starting motor cut-off

1020

0 0

Purge Time
Antisurge close command (L14 HS)

Firing & Warm-up Accelerate End Of Sequence (L14 LS)

Start the unit

- Reach crank speed (20% of TNH)
- Wait for purge time
- Ignition
- Warm-up time
- Acceleration to Minimum Load (FSR control: Start-Up control / Acceleration control / Speed control). Refer to H.D. typical start-up curve for
acceleration constant values
- I.G.V. will move according with speed and exhaust temperature (see comment on page 4).
- At 60% the starting motor will cut-off
- Once L14 HS speed relay is energized (Normally at 95% of TNH), the anti-surge valve will shut
- Once the End Of Sequence status (L3) has been reach, the unit is ready to operate.
 PGT 10 TYPICAL START-UP CURVE

= TTXM LP speed =
= HP speed FSR =

10800 L14 HS

L28FDX Flame detected

7900
0 DEG

HP LP
rpm rpm
I.G.V. -40 DEG

3950
L14 LS

Crank Speed
2160 W.U

Fire

0 0

Purge Time
Antisurge close command (L14 HS)

Firing & Warm-up Accelerate End Of Sequence (L14 LS)

H.P. Acceleration: RATED 1% Speed per second

RAMP 0,5% Speed per second

L.P. Acceleration: RATED 0,5% Speed per second

RAMP 0.5% Speed per second

Start the unit

- Reach crank speed (20% of TNH)
- Wait for purge time
- Ignition
- Warm-up time
- Acceleration to Minimum Load (FSR control: Start-Up control / Acceleration control / Speed control).
- I.G.V. will move according with speed.
- Once L14 HS speed relay is energized (Normally at 95% of TNH), the anti-surge valve will shut
- Once the End Of Sequence status (L3) has been reach, the unit is ready to operate.
- Nozzle will move at 100% of TNH (Nozzle position data are: +22 DEG open position; -8 DEG close position)

WARM-UP TEMPERATURE RAMP: 1°C/s

ACCELERATION TEMPERATURE RAMP: 2.5°C/s
RE-BIAS DOWN TEMPERATURE RAMP: 3°C/s
RE-BIAS UP TEMPERATURE RAMP: 1°C/s
 GE 10-2 DLN TYPICAL START-UP CURVE

= TTXM I.G.V. =
= HP speed LP speed =
11000 85% (open) 7900
88% 85%
9900 Combustion Air Valve
75%

End Of Sequence
424 °C
55%
397 °C
LP
HP 3950 rpm
rpm 337 °C
305 °C

Crank Speed Axial Compr. Antisurge

2200
Valve Command

0 0

Purge Time Antisurge close command

Firing & Warm-up Accelerate Ready To Load

H.P. Acceleration: RATED 1% Speed per second

RAMP 0,5% Speed per second

L.P. Acceleration: RATED 0,5% Speed per second

RAMP 0,2-0,3% Speed per second

During the ramp, verify the following significant step:

- The valve on premixed line must open during warm-up
- After warm-up the pilot valve starts to close, moving with ramp, from fully open to the acceleration value.
- During ramp the flashback thermocouples should increase gradually as TCD increases
- When the machine reach a certain speed (NHL) the control of combustion air valve is switched from open loop
(position imposed in function of compressor speed) to close loop as function of lamba_set and as a consequence
as function of measured fuel flow and combustion air flow: verify that the behaviour of the valve is stable.
- After a delay time from antisurge valve closure, the pilot valve control switches from the acceleration ramp value to
a regulation obtained by a function of the thermal load.
- During all the sequence verify also the proper operation of flashback thermocouples and the behaviour of pressure
oscillations (on RTSA and on control panel) taking note of the max. value achieved.
- On reaching Full Speed No Load, verify antisurge valve to be fully closed and check the DLN parameters not to
deviate significantly from the standard value.

WARM-UP TEMPERATURE RAMP: 1°C/s

ACCELERATION TEMPERATURE RAMP: 2.5°C/s
RE-BIAS DOWN TEMPERATURE RAMP: 3°C/s
RE-BIAS UP TEMPERATURE RAMP: 1°C/s
 PGT 5 - 2 TYPICAL START-UP CURVE

= LP speed CPD =
= HP speed CTDA =
10290
11140

L28FDX Flame detected

7200 (70%)

295 °C
HP Starting motor cut-off LP
rpm rpm

2° stage Nozzle (+12 DEG)

6.8 Bar
2228
Crank Speed

0 0

Purge Time

Firing & Warm-up Accelerate to end of sequence

H.P. ACCELERATION TRIP:

Rated: 111.4 rpm/s
Ramp: 55.7 rpm/s

L.P. ACCELERATION TRIP:

Rated: 102.9 rpm/s
Ramp: 51.5 rpm/s

WARM-UP TEMPERATURE RAMP: 1°C/s

ACCELERATION TEMPERATURE RAMP: 2.5°C/s
RE-BIAS DOWN TEMPERATURE RAMP: 3°C/s
RE-BIAS UP TEMPERATURE RAMP : 1°C/s

ANTISURGE VALVE CLOSE COMMAND: 90%

ANTISURGE VALVE OPEN COMMAND: 85%