Gas Turbine LM2500+ G4

There are five (5) types of shutdown sequences of GE Gas Turbines.

1. FSLO = Fast Stop Lockout with Motoring
2. FSWM = Fast Stop with Motoring
3. CDLO/NORMAL = Coldown Lockout
4. SDML = Slow Decelerate to Minimum Load
5. SDTI = Slow Decelerate to Idle

Gas turbine start sequence

1.       Purge sequence

1.1   The hydraulic start system is enabled and motor start is started.

Notes:

1.1.1          If there is no feedback of motor then “hydraulic starter motor failed”.

1.1.2          If GG rotor speed does not reach to 300 RPM then “Hydraulic starter failed”.

1.1.3          If GG rotor speeds 4500 RPM to 8000 RPM and gas turbine lube oil pressure does not above 6 PSIG then “Turbine lube oil supply pressure failed”.

1.1.4          If GG rotor speeds more than 8000 RPM and gas turbine lube oil pressure does not above 15 PSIG then “Turbine lube oil supply pressure failed”.

1.2   After 5 seconds of hydraulic system and motor started, GG is ramped up between 2200 – 2300 RPM (100%output of control).

1.3   When GG reaches 2000 RPM then purge timer is enabled.

Notes:

1.3.1          There is three (3) times of volume of engine and exhaust for purging.

1.3.2          During purging time, the permissive and finished to purge will be activated to relative system.

2.       Acceleration / fuel and ignition sequence

2.1   When purge is completed then acceleration / Fuel & ignition sequence is started.

2.2   GG is ramped down 1700 RPM and igniter is energized and hydraulic speed is ramped up to 100% of control.

2.3   Gas fuel primary and secondary shutoff valves are opened.

2.4   Start / Run permissive signal is sent to Fuel control (Woodward governor/MicroNet).

2.5   The “Fail To Lightoff Check Timer” is initiated.

Note:

2.5.1          If flame has not been detected and “Fail To Lightoff Check Timer” is timed out then “Fail To Lightoff Purge” is initiated and sequencing actions:

·         Gas fuel shutoff valve is closed.

·         Gas fuel vent valve is opened.

·         Gas fuel primary and secondary shutoff valves are closed.

·         Start/Run to fuel control (Woodward governor) is reset.

·         Igniter is switched off.

·         Purge timer is initiated, when it is timed out then hydraulic starter is de-energized and hydraulic motor is switched off respectively.

·         Shutdown sequence is initiated.

2.6   The flame is detected then “GG Acceleration Check Timer” is initiated.

Note:

2.6.1          If GG does not reach to 4500 RPM and “GG Acceleration Check Timer” is timed out then “GG Acceleration Failed” is initiated.

2.7   When “GG Acceleration Check Timer” and GG speed reaches 4500 RPM then “GG Idle Fail Check Timer” is initiated, vibration monitor inhibit is removed, igniter is switched off, hydraulic start system is cleared (0% control output) and hydraulic motor is stopped.

Note:

2.7.1          If “GG Idle Fail Check Timer” is timed out and GG speed does not reach to 6800 RPM then “GG Idle Speed Failure” is initiated.

2.8   When GG speed reaches 6800 RPM then acceleration/fuel & ignition sequence is completed and warm up sequence is initiated.

 3.       Warm up sequence

3.1   “GG warm up and PT breakaway Timer” is initiated.

Note:

3.1.1          If PT does not reach 350 RPM within 15 seconds then “PT Breakaway Failure” is initiated.

3.2   When GG warm up is timed out then GG idle signal to Woodward governor MicroNet Fuel control is cleared and GG increases speed to achieve PT minimum governor speed and “PT Acceleration Speed Check Timer” is initiated.

Note:

3.2.1          If PT does not reach to 2379 RPM and “PT Acceleration Speed Check Timer” is timed out the “PT Acceleration Speed Failure” is initiated.

3.3   When PT speed reaches to 2379 RPM then anti-surge controller, load sharing controller and compressor overall recycle controller are enable and “read to load” is set.

 

Hydraulic Start System

Fuel Gas System

Fuel Selection Logic, Woodward Governor

Continuous...

References:

1. GE LM2500+  Gas Turbine Generator Basic Operator / Package Familiarization Training Course.

2. Dresser-Rand Compressor (LM2500 G4 Driven) Control Systems Operation Manual.