We are facing lubricant dilution (with Hydrocarbons) problem for our Turbo-Expanders installed in the field. The lubricant viscosity drops and also the flash point lowers to dangerous levels. Therefore we have to frequently drain the contaminated lubricant and top up with fresh oil. We are using Shell Turbo T 100 as the lubricant.

This problem is occurring with all the turbo expanders and not just with one or two machines. Had anyone gone through such sort of problem in past? Advice / suggestions will be appreciated...

Regards,
Mohammad

Mohammad, I faced similar problem in my earlier job for turbo compressors and blowers in various services. Various vapours like Propane, Butane and MTBE leaked from seals were causing this problem. Solution was reselection of oil which can tolerane these hydrocarbons. Basically the new oils selected were inert to these hydrocarbons. I do not remember brand name now. You may ask oil manufactureres about this.

If one were considering a new installation, this is a consideration where magnetic bearings could have an advantage.

RR / Bill,
Thanks for the reply.

What about using Synthetic lubricants for the existing machines? Has anyone experience with synthetic lubes for this application?

Regards
Mohammad

Dear

It is a common problem on Turbo expanders as it is close loop with hydro carbons thro seals. The important parameter is oil viscosity if it dropped down add only higher viscosity oil and do not repeat DO NOT worry on Flash point as it wont get ignited as it is clsoe loop pressurinsed system.

We use successfully Turbo oil 100 with out any problem as I am handling 8 Turbo expanders of both Rotoflo and Mafitrence. Yes teh new units are now with magnetic bearings an edge over the old units.

Ramana,
Thanks for the response. I think you are right, its a common problem and related to the design.

We shall be looking for the magnetic bearings for the new units in future.

Regards,
Naseer