THEORETICAL-ANALYSIS OF TERNARY GAS-MIXTURE SEPARATION IN AN INTERNALLY STAGED PERMEATOR

Mathematical models based on perfect mixing and cocurrent flow patterns have been developed to describe the separation of a ternary gas mixture in an internally staged permeator. Separate recovery/enrichment of carbon dioxide and methane from a gas mixture of CO2-CH4-N2 has been considered in the simulation. The results indicated that the internally staged permeator can achieve a ternary gas separation and, under the operating conditions studied, each product stream generated by the permeator is enriched in a different gas component. A parametric study reveals that, in order to maximise the degree of separation, the values of both stage cuts and the pressure ratio across each membrane have to be properly selected. Results from a comparison study between the two flow patterns considered show that the performance based on cocurrent flow pattern is generally better than that of the perfect mixing.