Abstract
A set of nonlinear partial differential equations of material balance on pressure swing adsorption (PSA) is expanded around a small value of cycle time to study the effects of nonlinearity of adsorption isotherm on PSA performance. Solution of the zeroth-order term is given by a quadrature to predict the time-averaged concentration C, and the solution of the first-order term is given by an ordinary linear differential equation to predict the concentration swing ΔC. In the case of surface diffusion control, a moderately favorable adsorption isotherm is advantageous in that the column length required to attain the desired level of product gas concentration is minimized. The relative concentration swing ΔC/C is almost independent of the type of adsorption isotherm. The present analysis may be a good approximation if cycle time is less than the reciprocal of the volumetric mass transfer coefficient based on driving force of the amount adsorbed per unit bed volume.
