Force feed versus ring oil lubrication

[SENGUTTUVAN]

For one of the centrifugal pump and Hydraulic Power recovery turbine pump , the vendor is using Tilting pad bearings for thrust as well as Radial bearing. The rated kw of the Pump is 1200 kw . Vendor is offering to have ring oil lubrication ( No force feed with ext lube oil pump). As per Energy density formula given in API 610 this pump does not require Hydrodynamic lubrication. My query is , for tilting pad bearings , on reliability point of view , whether we can insist for Force feed lubrication? What are the factors to be looked into before accepting the ring oil lubrication for such a high power pump.Thanks to clarify

 

[romke]

from the point of view of lubrication i see no difference between forced feed lubrication or ring oil lubrication. in both instances (assuming that sufficient oil is supplied when the pump is operated) in a good design hydrodynamic lubrication can be achieved and should be achieved to get acceptable life of the bearings. during startup or shut down you problably will have temporarely mixed or boundary lubrication and higher wear will then take place. if you want or need to avoid that, only hydrostatic lubrication can help, and then not only a pump but also a regulatory system is needed to ascertain that both before the startup until after the complete standstill the bearings are supplied with sufficient lubricant with a high enough pressure to keep the bearings fully separated from the shaft and the thrust collar.

 

[electricpete]

As per Energy density formula given in API 610 this pump does not require Hydrodynamic lubrication.

To my thinking hydrodynamic has no high pressure pump, hydrostatic has a high pressure pump.
Do you mean hydrostatic? I don't know what API says but if the psi loading is too high then design rules push you in the direction of hydrostatic. The limiting condition is start/stop as stated. Frequent start/stop or need to rotate while secured may factor into your decision along with load.


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