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A detailed numerical model of a Skarstrom-like PSA process is used to investigate the separation performance of an adiabatic and a nonadiabatic process for removal of bulk CO2 impurity from inert He. The complexity of the gas phase adsorbate composition, adsorbate loading, and the adsorbent temperature profiles as functions of positions inside an adsorber at the start and end of each step of the PSA process are discussed. The separation performance of a nonadiabatic PSA process is generally inferior to that of the corresponding adiabatic process. Smaller adsorbent column diameter accentuates nonadiabatic operation and hence lower separation efficiency. Furthermore, the separation efficiency decreases more rapidly at short cycle times and smaller column diameters. Insulation of PSA columns of a process development unit operated under these conditions is recommended for reliable data analysis. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4066-4078, 2017 [ABSTRACT FROM AUTHOR]

The practical implications of replacing various individual transport resistances such as gas-solid mass and heat transfer, and gas phase axial dispersions of mass and heat in a numerical model of a pressure swing adsorption (PSA) process by a single, empirical, lumped, effective mass transport coefficient were evaluated. A non-isothermal, adiabatic, four-step Skarstrom-like PSA process for production of pure helium from a binary helium-nitrogen mixture using 5A zeolite adsorbent was considered. It was found that the above-described model simplification was adequate to describe key process performances such as the bed size factor and the product recovery vis-a-vis a detailed model where the effects of all individual resistances were explicitly included. [ABSTRACT FROM AUTHOR]

Significance A nonequilibrium, nonisothermal, nonisobaric model was used for numerical simulation of the efficiency of N2 desorption from a LiX zeolite column by rapid purge with O2 in a pancake adsorber. The key parameters included desorption time, adsorbent particle size, and the adsorber length to diameter ratio. The efficiency was found to be a complex function of these variables. [ABSTRACT FROM AUTHOR]

Abstract: Sorption enhanced water gas shift (SEWGS) reaction is a process concept, which simultaneously carries out the gas phase water gas shift (WGS) reaction (CO+H2O↔CO2+H2) and selective chemisorption of the byproduct CO2 from the gas phase reaction zone for direct production of essentially pure H2 in a single unit operation. A packed bed sorber-reactor containing an admixture of a WGS catalyst and a CO2 chermisorbent is used in the process. The concept circumvents the thermodynamic limitation of the WGS reaction and enhances the rate of reaction for H2 production. In this study, the SEWGS reaction concept was successfully demonstrated by both experiment and numerical simulation using K2CO3-promoted hydrotalcite as the CO2 sorbent. Numerical model simulations were also carried out to investigate the effects of various operating conditions of SEWGS reaction on the process performance. In general, higher H2O/CO feed ratio, higher fraction of sorbent (chemisorbent ratio in the sorber-reactor), and lower operating temperature favor both H2 productivity and CO conversion. Higher reaction pressure increases H2 productivity but decreases CO conversion. [Copyright &y& Elsevier]