The Calculation of a Serial Fed Gas Permeator System

The calculation methods for the serial fed multistage system were developed for the four flow pattern, i.e., perfect mixing, cocurrent flow, cross flow, and countercurrent flow, under the condition of constant membrane area or constant cut. The calculations were performed for two examples using permeabilities of polyimide. One is the case in which concentrate H2 is up to 95% in the total permeate stream from a 75% H2–25% CO mixture. Another is the case in which concentrate CH4 is up to 98% in the high-pressure stream from a 60% CH4-40% CO2 mixture. A brief parametric study shows that the system consisting of countercurrent flow modules under the condition of constant cut is most efficient among the case studied and should minimize the number of stages using big modules. On the other hand, the system composed of perfect mixing or cocurrent flow modules under the condition of constant membrane area is more efficient than constant cut, and it is advantageous to assemble a system using a large number of small modules. The performance of the system comprised of cross flow modules is identical with that of a single module.