Oil recovery problem in water cooled centrifugal chillers
Oil recovery problem in water cooled centrifugal chillers
(OP)
Hello to all..
During the low cooling load demand period combined with low ambient conditions, the problem of oil recovery to the oil sumps becomes very serious and sometimes the oli level in the sight glass dispappears, this requires oil charging. Again as the demands increases and also the discharge pressure increases the oil reappears forcing to drain the oil. My question is, is there a way to control the oil levl instead of this charging and discharging at varying loads.
The chiller in discussion is a large capacity (1000 Tons) water cooled centrifugal chiller.
Comments and suggestions are highly appreciated
Thanks.
During the low cooling load demand period combined with low ambient conditions, the problem of oil recovery to the oil sumps becomes very serious and sometimes the oli level in the sight glass dispappears, this requires oil charging. Again as the demands increases and also the discharge pressure increases the oil reappears forcing to drain the oil. My question is, is there a way to control the oil levl instead of this charging and discharging at varying loads.
The chiller in discussion is a large capacity (1000 Tons) water cooled centrifugal chiller.
Comments and suggestions are highly appreciated
Thanks.





RE: Oil recovery problem in water cooled centrifugal chillers
You may have better luck with a controls modification. You could artificially induce additional load through recirculation/bypass, or introduce a higher cutout to keep the chiller from running at loads that would cause oil loss.
I had a similar problem with a bunch of water-cooled screw machines. Luckily, they were all in the same building, and we were able to re-configure the loads on each chiller to minimize the effects. We routed year-round computer loads to problem chillers, for instance, and removed load from others.
You might try trending the oil return vs. loading, and make your own determination. As I recall, we found that it took very little additional load to put the chillers in a safe regime vs. lack of oil return.
It was a very irritating problem. As you suggest, the chillers would run lightly loaded with no apparent issue, then would shut down on low oil after a week or two at that condition.
RE: Oil recovery problem in water cooled centrifugal chillers
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RE: Oil recovery problem in water cooled centrifugal chillers
Purge units address very small quantities relative to a long-term degradation of the refrigerant, instead.
RE: Oil recovery problem in water cooled centrifugal chillers
Thanks....
RE: Oil recovery problem in water cooled centrifugal chillers
You may want to elevate this to another thread, and solicit responses from others more expert than me.
RE: Oil recovery problem in water cooled centrifugal chillers
We had purg units on all centrifugals and I suggest you try to get funding for them.
RE: Oil recovery problem in water cooled centrifugal chillers
As u have pointed out, HOT GAS bypass is in ON mode most of the time for artificially loading of the chiller. If I have not misunderstood your statement, could you please explain, How does a Purge unit eliminate the problem of low oil level during the low load conditions? and do u mean the OAM Purger units?.. If they (OAM Purge) are used for any other purpose than the above discussed point, can u detail here as to what benefits do u have using the purge units.
I hope I did not ask many points.
and as always many thanks to tombmech for the valuable advices.