(223c) Equilibrium Theory Analysis of Equalization Tanks in a PSA Process

Pressure equalization between beds and also between beds and tanks in pressure swing adsorption (PSA) processes are critical steps for achieving higher enrichment of heavier gas in the heavy product and higher recovery of light gas in the light product. However, only minimal attention has been given to the utilization of an empty tank in the pressure equalization step. This empty tank does not contain any adsorbent and is simply used as a medium for internal gas storage. This kind of equalization step is referred to as a bed-to-tank-to-bed equalization step. Equalization tanks can be useful to decrease the number of the beds and to decrease the number of idle steps in PSA cycle schedules.

To begin to understand the role of tanks in a PSA process, an isothermal equilibrium theory analysis is carried. Analytic expressions are derived based on linear isotherm and an arbitrary binary feed stream to describe the performance of a simple PSA process at the periodic state that produces a pure heavy component at high recovery. To observe the effect of the number and size of the tanks, the performances are analyzed in varying number of equalization steps and volume of tanks in terms of the different concentrations and velocity profiles exhibited during various cycle steps. The latest result from this study will be presented.