A NEW EVALUATION OF MEMBRANE PROCESSES FOR THE OXYGEN-ENRICHMENT OF AIR .2. EFFECTS OF ECONOMIC-PARAMETERS AND MEMBRANE-PROPERTIES

The optimum process configuration and operating conditions of a membrane process for the generation of oxygen-enriched air (containing a minimum of 30 mol% O2) have been identified previously [Bhide and Stern, J. Membrane Sci., 62 (1991) 13]. The present study reports the results of an economic assessment of the optimized oxygen-enrichment process. The effects of the following factors on the production cost of "equivalent" pure oxygen (EPO2) were considered: (1) cost of energy, (2) cost and efficiency of vacuum pumping, (3) plant capacity, (4) replacement cost of membrane elements, (5) expected membrane life, (6) effective membrane thickness, and (7) O2 permeability and O2/N2 selectivity of membranes. It is concluded that membrane processes for the oxygen-enrichment of air have the best potential of becoming economically competitive for small plant capacities (less than ca. 20 tons of EPO2/day) and at oxygen concentrations in the range of 30-45 mole%. The properties of polymer membranes required to develop an economically-competitive membrane process for the oxygen-enrichment of air are indicated.