Gland seal causing Steam Turbine generator to roll under vacuum 1

[Ryan Goffena]

Hello,
I am wondering if anyone has encountered a situation where gland sealing steam has made a steam turbine come off the turning gear while at a vacuum. If so, what was the cause or what needs to happen.

 

[byrdj]

sounds familiar.

verify header pressure and adjust for low end of design range. make sure there is no "head" on gauge used to set.

blame damaged inner ring shaft seals for the "pressure" sections.

the "work around" of securing lift pumps should be avoided.

keep oil temperture on the low side during TG opereation

allowing to self spin just above TG speed may not hurt the turbine, BUT could play havoc for the control system. (I am familer with valve pulsing for GE LSTG EHC)

 

[racookpe1978]

More likely, one or more of the governor valves are scored, cut, or worn so that they are not cutting off steam flow.

Have also seen cases where both GV and throttle valve are leaking by to cause the problem you describe.

 

[byrdj]

agree...In the case of both valves closed, there should be an in between drain to condenser if the first valve leaks to reduce that possibility. Not sure if the modern "combined" valves have that