Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
(OP)
Hello, I am new in the Eng-Tips forums and my background is not sufficient to determine the cause of the problems regarding the Oil Flooded Screw Compressor that I was dealing with.
I found conditions in the screw compressor oil in milk white condition after operation for 7200 hours. Conditions compressed gas composition has about 89 mole% Methane, Ethane: 3.5 Mol%, Propane: 1.5 Mol%, Butane: 0.5 Mol%, C6 +: 0.25 Mol% and CO2: 5 Mol%.
Upstream pressure of 24 bar with a temperature of 28 deg C and 28 bar pressure compressor downstream with a temperature of 60 deg C.
My question is, whether the damage to the gas compressor oil is due to the existing condensate in the gas will be compressed and whether the upstream temperature 28 deg C is still too low to cause the emulsion between gas condensate with oil?
Thanks for anyone who can help.
I found conditions in the screw compressor oil in milk white condition after operation for 7200 hours. Conditions compressed gas composition has about 89 mole% Methane, Ethane: 3.5 Mol%, Propane: 1.5 Mol%, Butane: 0.5 Mol%, C6 +: 0.25 Mol% and CO2: 5 Mol%.
Upstream pressure of 24 bar with a temperature of 28 deg C and 28 bar pressure compressor downstream with a temperature of 60 deg C.
My question is, whether the damage to the gas compressor oil is due to the existing condensate in the gas will be compressed and whether the upstream temperature 28 deg C is still too low to cause the emulsion between gas condensate with oil?
Thanks for anyone who can help.
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
The second issue is that many screw oils will absorb heavier hydrocarbons (like a lean oil NGL plant). You need to send your gas analysis to the compressor manufacturer and follow their recommendation on oil selection. With your analysis you'll probably be directed to a very expensive synthetic oil, but none of the less expensive mineral oils will work with that analysis.
The good news is that when I had exactly the problem you described, someone told me to raise the discharge temperature and all of my problems went away within a few days and never came back. Fixing the first problem just requires vigilance and persistence.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
I also did a test to degas the sample gas oil compressor oil which can be recovered visual along with my sample viscosity when heated at temperatures of 160 C. If this show is so great that damage portion of C6+ gas compressor oil?
Indeed, there is an opportunity for me to raise the temperature to be higher downstream by first heating the gas at the upstream side with Dew Point Heater. Is the upstream temperature will approach 45 C is still safe enough to go to the gas compressor?
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
I just wanted to add that sometimes this points to the compressor being oversized and not working hard enough. If you have multiple compresors, one solution would be to shift some load to this compressor by turning another compressor off. You could solve your oil issue and reduce energy costs.
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
Gas compressor only 1 unit available as a gas booster to the gas turbine.
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
might not be correct for application
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
After 7200 hours of operation the viscosity dropped from 68 to 41 Cst and followed with oil color changes to white milk.
There is one odd thing about the gas separator upstream side of the compressor. Is the gas separator inlet higher than the outlet can effectively eliminate the existing liquid in the gas?
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
If you dig into the Kobelco specs you'll find that the maximum allowable water vapor content in the inlet gas of 7 lbm/MMSCF (110 mg/Sm^3). Your gas content is closer to 400 lbm/MMSCF. Your exit water content is probably something like 50 lbm/MMSCF. The difference stays in the oil until the oil is fully saturated. That is why it is milky and the viscosity is high. You can't afford the fuel for the reboiler on an upstream dehydrator. Especially when you can actually fix the problem for a few hundred dollars. Oh yeah, you have a policy. Good luck with that.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
RE: Lube Oil for Flooded Oil Screw Compressor broken after 7200 operating hours
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"