TURBINE INLET PRESSURE ISSUES
TURBINE INLET PRESSURE ISSUES
(OP)
90 MW GEC Alsthrom turbine with inlet pressure issues. It seems every time the unit is cycled up and down the inlet pressure gets worse, design of the unit is 1350 but in years past we have always maintained 1280 to 1290 throttle prssure. As it stands at this point to run 80 net with a back pressure of 2.15 our throttle pressure is running 1375 to 1385 which gives us a sh 3 outlet pressure on the boilers just shortly under the safety lifting pressure 0f 1460. Our gland steam system has been overloaded for some time now, but since the last unit start the throttle pressure has come up another 10 to 15 pounds and the gland steam dump percentage has backed off as if the steam is not getting to the chest and to the bleads on the govenor valves. Large amount of vibration and high pitched noise at the left turbine stop valve.





RE: TURBINE INLET PRESSURE ISSUES
I think you are saying the boiler pressure had to be increased to obtain less MWs.
are you positive the control (governor) valves are going full open.
for the units I've seen, the stop valves are sized so that 100% can be passed with one closed, however real world is the flow would be reduced slightly
RE: TURBINE INLET PRESSURE ISSUES
Johnny Pellin
RE: TURBINE INLET PRESSURE ISSUES
RE: TURBINE INLET PRESSURE ISSUES
there should also be a reduction in feedwater flow
or
the increase in stage pressure indicates an increase in mass flow. if the mass flow goes through the turbine, there would be an increase in MWs. if the increase in flow is due to erision and opening of the steam path, the heat rate will suffer.
if there is a loss of MWs with the increase flow, then there would be a loss of mass from the steam path, possibly into feedwater heating
RE: TURBINE INLET PRESSURE ISSUES