I'm trying to estimate the amount of flash gas that will evolve from a produced water system when the upstream pressure is 9 barg and the flash vessel operates at 2 barg (40 degC). I've tried using Henry's law and obtained some very useful information from.
http://www.mpch-main.../res/henry.html
If you see the attached Excel, I've used Henry's law to estimate the amount of absorbed gas at the two conditions and the difference should be the flash gas. Now this is all theoretical and I've been told that I should do the following by a colleague.
If you are looking at how much dissolved hydrocarbon will flash out of produced water, the rule of thumb is that at atmospheric pressure the amount of hydrocarbon flashed off equates to approximately 50% by volume vapour and 50% by volume liquid water. If you use this as a guide you can back calculate the amount of flashed hydrocarbon that will break out at a higher pressure.
Now this is fine for getting concentrations, but it's useless in estimating the actual flow rate. I have a feeling that the outlet PCV will be a 2inch regulator, but I'd like to be able to correctly estimate the flow. Also, please note that this system in level controlled and any variation in the level will trip the system. Therefore the flash gas is the sizing factor.
Any advise would be appreciated.
Attached Files
Edited by BaneAUS, 25 October 2010 - 03:11 AM.