Separation of supercritical CO2 and water

[processinalaska]

Hi,

Is it possible to separate supercritical CO2 and water (200F, 1200psig, 100,000BPD)? We would like to maintain high pressure through the separation equipment and reinject the water to produce in another reservoir. We know that CO2 is corrosive and would like it out of our system. Any suggestions?

Thanks!

 

[BigInch]

If there is a density difference, you can pretty much speparate anything.

How much of the 100 KBOPD is water, how much oil(?) and how much is CO2?

Does the CO2 need to remain super? If not, why not reduce the pressure a bit and separate it using the phase difference?

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[processinalaska]

The critical density of CO2 is 10.6 mol/L at its critical point (87 deg F, 1073 psi), and of water is 17.9 mol/L at 705 deg F and 3190 psi. I'm not sure of the densities at 1200 psig and 200 F.

We're pumping from a water reservoir, so there's no oil. The concentration of CO2 varies from 5-6 mol% (as reported downhole) up to 34 mol% (at 4000 psig).

The CO2 doesn't need to remain supercritical, and we think either a vacuum degasifier or membrane degasifier might work. But I'm not sure of the pressures of CO2 and water coming out of those systems.

 

[25362]

Dissolved oxygen is also considered corrosive. What is its concentration ?

 

[processinalaska]

There's no oxygen in the well water. None reported anyway.

 

[topspy]

Off topic, and WELL outside of my expertise: I am trying to learn what I can about supercritical extraction (think aerogels) in order to 'homebrew' my own equipment on the cheap. Can any of you chemical/mechanical types give any suggestions on PRV's, methods, procedures, etc.? I'd like an extraction chamber of about 100 sq/in or so.... Information on this subject seems to be hard to find (at least regarding the practical details.) Thanks!

 

[StoneCold]

topspy
You should not hijack someone elses thread. I have seen test equipment for supercritical experiments done with a penberthy sight glass and small gear pumps.

processinalaska
If you used a vacuum degasifier then the inlet pressure to the unit needs to be less than 1 atm absolute. Hence the name Vacuum.
A membrane might work but I would go for the phase separation below the critical point. I guess that it really matters what you are using the water for and what pressure you need?

Regards
StoneCold

 

[unclesyd]

processinalaska,
Try a little reasearch into SCF (Super Critical Fluids/Extraction) using CO2.

I can't give you the specifics but the addition of very small amounts of a third component will greatly enhance the the seperation of CO2/Water.

 

[processinalaska]

Hi all,

Thanks for your input. We're now thinking of using a hydrocyclone for the phase separation. I hope it'll work out.

 

[dcasto]

The CO2 and water will separate with about 12% of the water staying in the CO2 and .3% of the CO2 in the water. The seperator calculates out at about 8' in diameter by 14' in height.

I'd recommend staying away from a cyclone separator because of additional shearing and mixing beyond equalibrium.

You can remove the CO2 from the water with a vacuum, I've run this type operation before. The trick is to use a two tray packed column to get the CO2 to release throughout the whole stream. We ran ours at 1 to 2" Hg absolute.