CO2 removal from O2 in Diving application

[fred29653]

I wonder if it would be possible to remove CO2 from an oxygen mixture used in breathing apparatus.
By remove I mean reduce by a percentage (50% would be nice). I will be continuously recirculating the gas through the membrane. The gas mix will be 98% oxygen and 2% CO2. There will be a high water vapour content so the membrane should be able to tolerate this. The delta P that we have to work with is 30 psi (2 bar).
Is this a non starter?

 

[jost]

There are some papers and patents on this topic.
Se e.g. US 3,910,780 and other patents citing this one (bonaventuraa, Trachtenberg etc. Articles see e.g. Li and Teo, Trans IChemE vol 74 A nov 1996, pp856
yours

Jost

 

[fred29653]

Thanks for the response, the patent you mentioned is not exactly relevant to my application as it is a gas/fluid tranfer membrane. My application is a gas only membrane as my breathing apparatus will not be in the water.
Do you have any more reference material that you think might be relevant to my research.

Fred

 

[jost]

Dear Fred read all the patents by Trachtenberg!
Also search for patents covering gas purification via membranes etc

I only provided you with a good startingpoint.
Fluid = gas or liquid.
A lot of the stuff is relevant for both liquid and gas.

Gas to gas is also possible, ie purifying air from CO2 in space applications via membranes.

This is definately not a non starter. This kind of equipment can be built!

Trust your instinct

jost

 

With a membrane system, the question is how much oxygen can you afford to lose with the CO2. Without knowing temperature or absolute pressure information, literature suggests that you may get selectivities as high as 5-6.

Loss of water is also an issue, most membranes permeate water faster than O2 or CO2.

 

[fred29653]

Thanks for the response. Perhaps I should rephrase my question at this stage an ask if anybody can advise on whose membranes are likely to be the most suitable.
The loss of water is not as much of a problem as ability to tolerate water vapour. The best membrane will retain most of the oxygen and pass carbon dioxide and water vapour at a low differential pressure (2 bar)

 

At a selectivity of 5, I think your permeate stream will be about 90% O2. Is this workable? If not, I don't think that you can get there with a polymer membrane, and you will have to go to a gas/liquid system or maybe an inorganic membrane.

If that much loss of O2 is acceptable, I will try to get a better model with exact figures

Dave