Abstract
A method of graphical solution of ordinary differential equations, derived on the basis of a short cycle time approximation, is proposed to evaluate the performance of pressure swing adsorption. The longitudinal distribution of the time-averaged concentration CA is obtained by graphical integration of the reciprocal of the effective driving force, which is found graphically by the construction of the operating line (which relates concentrations between the adsorption and desorption steps) and the tie lines (which relate bulk and surface values). The concentration swing ΔCA is solved as a function of CA by the isoclinal line method, in which the current coordinates are simply constructed to determine the direction of a tangent on a ΔCA - CA diagram. Simplified construction procedures are discussed for special cases of surface diffusion control, film diffusion control and linear isotherm. The usefulness of the proposed method is comfirmed in an illustrative solution.
