Screw compressor / shared oil skids ? 1

[jamesbanda]

Dear all,

I am working on a project using screw compressors two/three (to be confirmed). Our leadership have suggested for the lubrication oil we use only one oil system. (ie the wetted parts of the lub system)

In my experience i've never seen this but what are others..
our unit size is too big to have one compressor..

 

[pipehead]

Having a common oil system makes no sense. Economics, the piping to interconnect will out weight the savings of economy of scale.
Security of flow (downtime) with a common system if the oil system goes down, then the whole system stops.
Turndown, the seperate systems are portable and have full turndown.

 

[jamesbanda]

FYI pipehead,

the compressor manufacturer have confirmed they have used combined oil skids for several clients and apparently they offer savings.
but i agree your coments are totally valid for reliability reasons

 

[unclesyd]

We have two SS rotary screw compressors in series, same prime mover, that have operated since the later 70's with a common oil supply. We are compressing a very corrosive product, NOX, and have two incidences where the oil was contaminated with NOX. Both time were when the second stage crashed and completely wiped out the seals on both rotors in the compressor.

 

[JJPellin]

There are very few absolutes when it comes to this sort of thing. In very general terms, I would usually insist on separate oil skids. But, there are exceptions. We have two flooded screw compressors that share a common flood oil system and common lube oil systems. In this case, there would be little advantage in having separate systems. Both compressors must be running in order to keep the unit on line. If one compressor shuts down, both must shut down and the unit must shut down. They are side by side so the additional piping cost to interconnect them is minimal. In this case a common system makes sense.

We have another similar case with two large barrel pumps that share a common oil system. By using a common oil system, we were able to justify upgrades to make the oil system very reliable. It is fully redundant in all critical components. It is highly instrumented. It is all stainless steel. It is state of the art. If we purchased two separate systems, we would have probably had to compromise and buy less reliable systems without all of the features we wanted.


Johnny Pellin