REMOVAL OF CO2 FROM A BREATHING GAS-MIXTURE USING A HOLLOW-FIBER PERMEATOR WITH PERMEATE PURGE AND ABSORPTION

A hollow-fibre permeator containing silicone rubber membranes has been used for the removal of CO2 from a breathing gas mixture. The effect of permeate gas absorption with water in the shell side of the permeat or has been investigated and compared with conventional systems with a nd without permeate gas purge. Experimental results compare favourably with theoretical predictions. It has been shown that the use of an aq ueous solution as an absorbing medium in the permeate side of the perm eator can greatly improve CO2 separation from the gas mixture and redu ce the need to maintain a high pressure ratio across the membrane. The improved CO2 selectivity is found to be caused mainly by the liquid f ilm which, however, creates film resistance, resulting in much reduced CO2 permeation flux. The CO2 permeation flux can be improved using an alkaline solution instead of neutral water.