TRANSPORT AND PERMEATION PROPERTIES OF A TERNARY GAS-MIXTURE IN A MEDIUM-SIZE POLYSULFONE HOLLOW-FIBER PERMEATOR

Permeation properties were analyzed for a mixture of CO2, O-2, and N-2 in a medium-size polysulfone hollow fiber permeator with a net permea tion area of 4.22 m(2). Measurements were conducted as a function of f eed composition, reject flow rate, and feed pressure. Results included variations in species permeability, separation factor, permeate enric hment, reject depletion, and stage cut as a function of system paramet ers. Variations in permeation properties show strong dependence on fee d composition, reject flow rate, and feed pressure. Permeability of ca rbon dioxide was higher at larger feed pressures and higher carbon dio xide content in the feed stream. Effect of increasing the reject flow rates on the permeability of carbon dioxide was affected by the system pressure and the carbon dioxide content in the feed stream. At low pr essures, increase of the reject flow rate resulted in a decrease of ca rbon dioxide permeablity. The opposite behavior was obtained at higher feed pressures. Increase of the reject flow rate reduced the gas resi dence time within the permeator. Increase of reject flow rate reduced species residence within the permeator and in turn increased resistanc e to species transport within the permeator. However, higher system pr essures and carbon dioxide content in the feed stream resulted in larg er levels of membrane plasticization, which increased the permeation r ates of all species. The combined effect of reducing the species resid ence time within the permeator and the level of membrane plasticizatio n favored the permeation of carbon dioxide versus the other two specie s. Variations in other permeation properties, which include oxygen and nitrogen permeabilities, stage cut, permeate enrichment in carbon dio xide, and reject depletion in carbon dioxide, were also explained in t erms of resistances encountered within the permeator and the membrane.