29-11-2012, 12:32 PM
Pre warming of turbine cylinder
Turbine Prewarming.pptx (Size: 2.58 MB / Downloads: 44)
Pre warming of turbine cylinder and main stop valve:
Check prior to pre warming :
Verify HP governing valves are closed , reheat steam pressure is
0.4 to 0.8 MPa at a temperature of 200~250°C and keep a
superheat degree of over 50˚C.
Verify the turbine barring gear has been put into operation and run over for
2 hours.
Verify the shaft seal has been put into operation.
Verify the condenser’s vacuum is not lower than 78kPa.
Verify the inner wall metal temperature of HP inner casing at
governing stage is lower than 150°C.
Cylinder warming operations:
Fully open the drain valve of HP main steam pipe, force close
HP exhaust check valve and verify all the extraction check valves
of HP cylinder are closed.
Fully open the drain valve before HP exhaust(CRH) check valve.
Fully open the drain valves of HP & IP inner casing jacket heating.
Fully open governor valve case mixing drain valve.
Fully close the ventilation valve(VV).
Press the button “LATCH” to latch the unit, and place DEH to AUTO position.
Press the button “PUTIN” for HP cylinder pre warming to prewarm
HP & IP cylinders.
Gradually open the warming steam flow control valve( RFV)
to let the warming steam flow into the cylinder with the pressure
at governing stage at 0.4~0.5MPa.Control the cylinder metal temperature
rate not to exceed 50˚C/h and check the temperature difference and
expansion difference of each wall of cylinder.
Precautions during pre warming :
Warming temperature rise rate must not exceed 50˚C/h.
When the temperature difference and expansion valve between
walls during warming are within the allowable range, and the lower wall
temperature is obviously higher than that of the upper wall, the drain
valve on cylinder body may be closed.
When the rotor impulse starting has been enabled by the
prewarming steam, it is required to reduce the prewarming
steam pressure as appropriate( by adjusting the opening extent of HP
and LP bypass or turning down the RFV ), and do not put the turning gear into operation once again until the rotor comes to a standstill.