Effects of Processing Variables on Gas Separation by Membranes

8A Effects of Pressure Ratio and Separation Factor on Recovery 

If liquids are present in the gas separation process, a liquid film can increase the membrane resistance markedly. Liquids can also damage the membrane by chemical action or by swelling or softening. If water vapor is present in the gas streams, the dew point may be reached in the residue product and liquid condensed. Also, condensation of hydrocarbons must be avoided. 

8B Effects of Process Flow Patterns on Separation and Area 

The required membrane areas for the same process conditions and air feed versus stage cut were also determined (W5). The areas for all four types of flow patterns were shown to be within about 10% of each other. The countercurrent and cross-flow flow patterns give the lowest area required. 

In general, it has been concluded by many parametric studies that at the same operating conditions the countercurrent flow pattern yields the best separation and requires the lowest membrane area. The order of efficiency is as follows countercurrent cross-flow cocurrent complete mixing. 

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