VRU-Liquid Ring Compressors
VRU-Liquid Ring Compressors
(OP)
Would you have experience with using liquid ring compressors/vacuum pumps for a VRU? The water seal causes quenching and condensation of some HC and water vapors and the discharge gas from the separator is saturated vapour. In cold weather there's 2 phase flow on the discharge piping from HC/water condensation.
Wouldn't there also be some scaling issues from the (make-up) water?
Wouldn't there also be some scaling issues from the (make-up) water?





RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
I have seen a few wreck on pipe scale and sand,along with coke and other stuff in flare gas recovery service and vacuume service. I can just imagine what would happen in VRU service.
Make up water scaling in not something I have really experienced, but I can assure you liquid ring machines won't like scale...
"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change?" Oddball, "Kelly's Heros" 1970
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
To me the big issue with liquid ring machines in VRU service would be compatibility between the gases/vapors and the seal liquid. In moderately heavy hydrocarbon service you often end up with stuff that is a vapor at the suction pressure and a liquid at the discharge pressure (and then a vapor again when the mixed liquid makes the next loop). There have been a lot of cases where this near-vapor liquid has been very drying and caused seals/wear points to fail. If you're going to use liquid-ring machines, you need to be really careful to select a seal liquid that will provide the necessary properties at the required pressures and temperatures to work with the vapors you are recovering in your unit.
Your question about scaling issues with the makeup water indicates that you have already decided that the seal liquid must be water. If your process analysis indicates that water is the best choice, then fine. I've seldom seen that to be the case in a VRU.
David
RE: VRU-Liquid Ring Compressors
And then there are the standard recip compressor issues in VRU service, failed valves, rings and riders...
So maybe a liquid ring is no worse.. We use them in flare gas recovery service in refineries a lot.. For the most part they work.
I know one of the projects we have going is set up with a liquid ring on the first stage, and then a recip on the second. The project I am currently working uses screw compressors for both the first and second stage...
"Why don't you knock it off with them negative waves? Why don't you dig how beautiful it is out here? Why don't you say something righteous and hopeful for a change?" Oddball, "Kelly's Heros" 1970
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.
RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
The discharge from an Ejector is not necessarily saturated. This depends on a number of things, including the condition and quality of the motive gas.
I do take your point however about winter ambient and the length of any discharge line.
RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
RE: VRU-Liquid Ring Compressors
-variation of discharge pressure due to the degree of condensation wrt to the weather and wind
-variation in discharge pressure due to variation in suction condensibles concentration