Idle Speed for Steam Turbine 1

[Rafael Dos Santos]

what will happen if we let steam turbine runs on idle speed too long? lets say the idle speed is 900rpm. Is there any abnormalities will occur on equipment? The steam Turbine is driving a compressor, centrifugal (over hung type)

 

[JJPellin]

You need to provide more information. If it is a condensing turbine, it may overheat without enough load. If it is a back-pressure turbine, it might be just fine. How fast does it normally run? What are the inlet and outlet steam conditions? Single stage or multi-stage? What type of bearings?

Johnny Pellin

 

[boo1]

don't forget about shaft nodes at that speed

 

[Rafael Dos Santos]

Thank you guys for answering for question. Im sorry about the details. Here..

Details Turbine:

Turbine type:
Condensing Turbine (Multivalve multistage)

Service :
Heat Pump Compressor Steam Turbine

Speed :
4757 (normal)
900 (idle)
3400 (Minimum speed)

Steam : - Inlet = 52.8 Bar A (390.6°C)

And why is "it may overheat without enough load"?? can you elaborate?
Thanks again guys

 

[JJPellin]

Without a load, the steam passing through the turbine is not giving up much energy. It is still too hot when it gets to the exhaust. A turbine like this should have a high exhaust temperature alarm at about 250 F (121 C). If the bearing design is not very good, you could experience a bearing failure because of inadequate oil film. We wiped the bearings on a similar turbine when slow rolling at 1000 rpm for 30 minutes. We ended up redesigning the bearings to reduce the unit load. We changed from a five pad to a three pad design.

Johnny Pellin

 

[Rafael Dos Santos]

owh..thanks JJPellin. you have been helping me alot with this and other questions.. thanks again..