Characteristic of air separation in hollow-fiber polymeric membrane for oxygen enriched air clean combustion applications

The characteristics of air separation in a hollow-fiber membrane unit are investigated numerically aiming at generation of highly oxygen-enriched air for clean combustion applications. A 2D axisymmetric mesh was generated using Gambit software and, then, was fed to Fluent 12.1 code. Detailed numerical study is presented for air separation using different polymers. Effects of sweep gas flow rate (from zero flow up to 1.15 × 10⁻⁷ kg/s), feed gas flow rate (from 3.3 × 10⁻⁹ kg/s up to 5.89 × 10⁻⁸ kg/s), fed pressure (from 2 atm up to 10 atm) and membrane polymeric material (considering TR-PBO-co-PPL-28 and TR-PI-g-CD) on permeation fluxes and concentrations of O₂ and N₂ are investigated. Targeting higher exit O₂ concentrations, multi-stage air separation unit is developed. The developed unit consists of three stages and the achieved oxygen mass fraction at outlet of first, second and third stages are 0.517, 0.8 and 0.914. Higher stage cut ratio is gained in the third stage as compared to first and second stages.