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Maintenance Man
23-09-2009, 11:50 AM
I need some technical assistance for some Howden compressor we have installed in our plant. In the past several months we have rebuilt several compressor due to oil related problems. We are fairly confident with the design of the compressor, but have some questions regarding oil flow into the compressor and the economizer port.

Model number: WRV XTS 321 L/D 1.32
Gas: Propylene
Suction Pressure: 3.5 - 4 kg/cm2
Discharge Pressure: 19 – 25 kg/cm2
Economizer port - 8 kg/cm2


Oil flow into the machine is of a concern because we have poor oil separation and associated oil carry over. Our design contractor has suggested that we decrease the oil flow to the compressor to increase the superheat and get better separation. The theory is acceptable, but we are a little concerned about how to decrease the flow.

We have reckoned we can lower the overall differential oil pressure (oil supply – compressor discharge) thus reducing the amount of oil flowing to the entire machine, or individually throttle flow to one of the four oil inlets into the machine. Our oil inlets are of standard configuration; one to each of the non-drive end bearings, one to the drive end bearings / balance piston, and the final to the slide valve. We are currently favoring throttling flow to the slide valve. What we are looking for is some guidance regarding the best way to decrease oil to the machine and any potential risks.

Regarding the economizer port we were trying to determine the needed pressure to flow gas into this port. Based upon its proximity to the discharge we figured that we would need to be close to the discharge pressure to flow into the port. If you could enlighten us on how to calculate this it would be much appreciated.
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