Equilibrium theory for solvent vapor recovery by pressure swing adsorption: analytic solution with velocity variation and gas-phase capacity

Equilibrium theory has been used to analyze the effect of velocity variation and gas-phase capacity on the performance of a pressure swing adsorption-solvent vapor recovery (PSA-SVR) process. An analytic expression for the wave interaction that transpires between the inlet feed conditions and the initial column conditions is developed. The periodic state is formulated by forcing repetition of characteristic conditions to obtain a polynomial equation. It is found that both velocity variation and gas-phase capacity have significant effects on the depth of wave penetration. For systems with relatively low feed concentrations, gas-phase capacity has a larger effect than velocity variation and vice versa for systems with relatively high feed concentrations. The analysis also reveals some remarkable insight into the subtleties associated with nominal purge-to-feed ratios of less than unity. (C) 1999 Elsevier Science Ltd. All rights reserved.