Power plant and calculations: Steam turbine, cold, warm & hot start up procedure

Turbine cold start up procedure

· Check all turbine interlocks and protection of turbine.

· Ensure MOT level normal.

· Ensure DP across the Lube oil and Control oil filter is normal.

· Start AOP and fill up the overhead tank up to normal level. Put the EOP in Auto mode. Maintain the oil temperature within the range of 40 to 45 deg C by MOT heater on, if required. Cut off the MOT heater manually after getting 40 deg C. (Note: The minimum oil temperature for turbine start up is 25 deg C as per OEM manual). Keep stand by AOP in auto made.

· After getting the above said temperature, start Vapour Extractor fan then start JOP. Ensure its normal discharge pressure i.e. 150 kg/cm2.

· Put the TG on barring gear and at this speed, record vibrations & temperature at all bearing points.

· Ensure TG runs on barring gear at least 1 hour prior to rolling. (Note: Prior to start up the steam turbine, the turning gear is operating for at least 25 minutes as per OEM manual).

Ensure hot well level normal i.e. 850 mmwc. Start CEP and put the system in recirculation mode. If required, make up the hot well level normal by make up
Control valve from surge tank. Put stand by CEP in auto mode. Keep Hot well control in auto mode.
Ensure cooling tower fore bay water level normal i.e. 60% and start MCW pump to circulate the cooling water through the condenser. Ensure l/L, O/L valve of condenser and l/L valve of cooling tower opened before MCW pump starts.
Adjust the I/L valve of cooling tower in such a way that, CW flow should not beyond the design value.
Open all the drain 100 % of main steam line and keep warm up vent in minimum position and open MSSV bypass valve fully at main steam pressure of 60 kg/cm2 & temperature of 350 deg C.
After ensured all condensate removed & colorless steam comes through drains, keep all the drains in crack position, then open main steam stop valve and close the by pass steam valve.
Charge the PRDS of Ejector and gland sealing PRDS line; ensure ejector pressure is of 10 kg/cm2 and temperature of 325 deg C. Adjust the HP & LP side gland sealing pressure at 1.1 ata. Maintain the sealing steam temperature of 393 deg C at HP side and temperature of 250 deg C at LP side.
Prior to pulling the vacuum, ensure vacuum breaker valve is closed. Then pull the vacuum through hugger ejector.
After getting vacuum -0.7 kg/cm2 through hugger ejector, take the main ejector into service and keep both the ejector in parallel and ensure the vacuum of - 0.93 kg/cm2 through running ejector, keep the main ejector in running and slowly close hogger ejector air line and then close the steam line after ensuring vacuum stable after STG synchronized only.
Ensure the Steam pressure at TG I/L is above 70 kg/cm2 (Alarm at 65 kg/cm2, Tripping at 52 kg/cm2), steam temperature at TG l/L is above 420 deg C (Alarm at 395 deg C, Tripping at 385 deg C), vacuum is above -0.7 kg/cm2 (Alarm at - 0.65 kg/cm2, Tripping at -0.5 kg/cm2). Acknowledge all the alarm in the annunciation panel/DCS and ensure all parameters are in healthy condition. Then reset the ESV of turbine through DCS to proceed for the rolling.
Ensure ESV opened & control valves are at zero position after reset the ESV. Give run command in Woodward 505E and observe the speeding should be carried out according to start up curve, respecting the preceding standstill (soaking) time (thermal condition of turbine).
At every soaking period, record/check all the critical parameters with respect to speed as follows:

1. Oil pressure & temperature

2. Bearing metal temperature

3. Main stream pressure & temperature

4. Exhaust steam pressure & temperature

5. Axial displacement

6. Vibrations

What do you mean by turbo supervisory system???

Ensure barring gear motor is switched off in auto as per interlock
If the oil temperature after oil cooler gets near to 48 deg C, adjust the cooling water O/L valve to maintain the oil temperature 49 deg C by keeping its I/L valve full open and ensure oil temperature should not below the 45 deg C.
If we prefer the rolling in manual, follow the start up curves and raise the speed as per start up curves and record above mentioned parameters at every soaking period Note: Cross the Critical Speed range as fast as possible.
Keep exhaust hood spray in auto mode. (Note: Do not allow exhaust steam temperature to exceed 105 deg C. Load Turbine or shut it off in case temperature keeps increasing.)
Start synchronizing by excitation on and voltage build up, match the DG voltage and frequency with generator voltage and frequency. When frequency and voltage matches within tolerable limit and synchroscope LED glows and allow to close the breaker. Close the breaker and increase the load on TG as per load curve (i.e. Approximately 2% of its rated load in order to avoid the activation of reverse power relay) up to the rated load by pushing the corresponding keys on the WOODWARD GOVERNOR
Adjust the Generator Air Cooler cooling water O/L valve to maintain the ‘Generator winding temperature by keeping its I/L valve full open.
Close all the main steam line drains and vents.
Start Remaining MCW pump and CT fan one by one to maintain the vacuum and exhaust temperature.
As per interlocks, after getting the steam flow of 60 TPH or more than 60 TPH at TG I/L, QC NRV of both bleeds of 22 ata & 9 ata respectively and control extraction of 3 ata will be reset.
Charge the Deaerator through control Extraction and ensure Deaerator pressure reaches at 1.5 kg/cm2 & temperature at 100 deg C at least.
Charge both the HP heaters and ensure Feed Water is charged through HP heaters prior to charge steam side.

TURBINE WARM START UP PROCEDURE

When after a clearly detected tripping the causes is eliminated or when the turbine is shutdown intentionally, observe the following for standstill’s longer than 5 minutes up to max. 8 hours

Refer the Warm Startup Curve given by OEM

Keep the live steam line up to the emergency stop valve pressurized and gland steam open unless turbine rests far longer than 60 minutes
Pre-warming the control valve block is not required
Open turbine drain(live steam)
The oil unit remains in full operation: the turbine oil should not be cooled below 45 deg C
Keep the turning gear in permanent operation
In case of no-uniform cooling-down process of turbine and rotor or drop out of turning gear (in this case immediately all isolation valves and steam to the labyrinths), slight distortion may arise, probably within the design clearances. This occurs especially with turbine arrangements where the turbine is exposed to an air draft.
In the case of a failure of turning gear motor or fall-out loss of electric power turn manually the turbine shaft by means of turning gear hand wheel each 5 minutes of must be turned manually at least 2 turns. If turning unexpectedly is not possible, at all circumstances do not apply undue force but let the turbine cool down.
Observe the instructions given & check for smooth action of the turbine at speed increase when starting again. Only a completely uniform warmed up turbine rotor is in straight condition so that further acceleration may take place without any risk.

SOP FOR TURBINE HOT START UP

Refer the Hot Startup Curve given by OEM

Check the availability of import power and start DG set.
Open the warm up vent and chest drains.
Start AOP, MCW & CEP pumps.
Maintain the hot well level 50% through make up
Close the Vaccum breaker valve and restart the Vaccum pulling.
Keep the barring gear motor in auto.
Maintain the lube oil temperature 45 deg C.
Check the overhead tank healthy condition.
Check the availability of Vaccum, main steam pressure and temperature.
Inform to higher officials about all parameters in healthy condition for rolling.
Reset the turbine and give for rolling.
Check the vibrations, bearing temperature and any abnormalities.
After turbine attend 6800 RPM give clearance for synchronization.