AXIAL DISPERSION EFFECTS ON GAS PURIFICATION PSA PERIODIC STEADY STATE

Abstract

The counter current flow (CCF) analogy of Suzuki {1985} for short cycle time, isothermal two step PSA of a dilute, single component in an inert carrier is extended to include the contribution of axial dispersion. For a linear isotherm an exact solution is derived. With a non-linear isotherm an approximation is used and the calculated periodic steady state profiles compare well with those from numerical simulations based on orthogonal collocation. The approximation also compares favorably with experimental PSA data in the literature for strongly non-linear isotherms and appears to be valid for PSA whenever the basic assumptions of the CCF model apply. For low Peclet numbers, a significant difference exists between the concentration at the bed inlet predicted from the Fickian model and the feed concentration.

KEYWORDS:

• Gas purification
• Adsorption
• PSA (pressure swing adsorption)
• Periodic steady state Pollution
• Axial dispersion