Computer analysis and design of pressure-swing adsorption cycles

The industrial process of Pressure Swing Adsorption (PSA) has many applications in gas separation systems and chemical reactor design. This thesis studies mass and heat transfer in several variants of this process. It also analyses important considerations such as cost efficiency, energy efficiency and product recovery associated with PSA processes.; Computer models for PSA processes in which gas flow is controlled by pistons and by a multi-port rotary valve are developed and calibrated against experimental results. Several operating cycles for a six-bed and a four-bed configuration an studied and effects of pressure ration, peak cyclic pressure, adsorbent isotherm, adiabaticity and valve timing on of pressure ratio, peak cyclic pressure, adsorbent isotherm, specific power consumption, productivity and recovery are investigated. Multi-bed cycles are simulated for both air separation and for the separation of hydrogen from syngas. For the latter studies, the computer model is extended to cover three active components: hydrogen, nitrogen and carbon dioxide.; All real PSA apparatus operates in a regime somewhere between isothermal and adiabatic, tending towards the adiabatic extreme with increasing scale. To predict process efficiency, or to scale up from bench-top to industrial scale, it is necessary to predict the temperature changes that take place as the process approaches equilibrium, and the cyclic temperature changes at equilibrium. The interaction between heat transfer, pressure changes, and the enthalpies of adsorption and desorption is complex and poorly understood. The computer model helps us to unravel some of this complexity.