Numerical Analysis and Optimization of Oxygen Separation from Air via Pressure Swing Adsorption

A pressure swing adsorption air separation process in a commercial aircraft using 13X zeolite with a more complex cycle than the classic Skarstrom was simulated via a predictive dynamic model to evaluate and optimize oxygen generation system. The coupled mass, energy, and momentum differential equations were discretized using the implicit central finite-difference technique and the obtained equations were solved by Newton-Raphson method. The validated model in conjunction with an optimization procedure (Successive Quadratic Programming) was utilized to investigate the oxygen separation efficiency as a function of beta (ratio between the bed time constant and the particle diffusion time constant), C-fp (purge orifice coefficient), theta(cycle) (cycle time), C-ff (feed valve), C-fe (exhaust valve) and pH* (high pressure operation). A set of optimum values (beta=150, C-fp=0.7, theta(cycle)=1.5, C-ff=31, C-fe=52 and pH*=3.8) was obtained and recommended to achieve maximum recovery (0.26) at 98% purity.