Hi Dear,

We have 4 Gas turbine frame 9e.03 can any body tell me while we are using bearing lift oil pump. Pump discharge is 240Bar to Generator Bearing how much shaft is lift through this pressure. means to say who much clearance is around bearing and shaft to give an oil seal between bearing and shaft.

Another question is why only in big frames this jacking oil system is provided by manufacturer not on small Gas turbine. Any idea kindly share.

Thanks

 

Ghulam,

"Jacking oil" (or "Lift oil") is used to provide lubrication for very heavy shafts in relatively "small" bearings. By using jacking/lift oil a smaller, more compact machine can be manufactured than if a much larger bearing had to be used because of the weight of the shaft.

Jacking/Lift oil is usually only necessary during low-speed operation, when the oil wedge developed by the rotation of the shaft is not thick enough to protect the shaft and bearing from damage. So, high-pressure oil is used as kind of a hydraulic wedge during low-speed operation until the normal oil wedge can provide the necessary distance between the shaft and bearing for lubrication and protection.

Hope this helps!

 

Thanks CSA for reply could you please let me know the how much is clearance between shaft and bearing during Lifting at slow rpm.

 

If the generator bearings have proximity probes you can measure it yourself.

 

If the generator bearings have proximity probes you can measure it yourself.

I have a question about turbo-generator jacking systems.
Generators typically have a jacking system but don't have an emergency or backup jacking system.

Assume the generator and turbine trip or shut down for any reason, but the jacking pump fails to start (due to a malfunction). What happens? The shaft speed is decreasing, but the generator's jacking pump isn't running.