Simulation of five‐step one‐bed sorption‐enhanced reaction process

Abstract

AbstractA five‐step, one‐bed, sorption‐enhanced reaction process proposed by Carvill et al. in 1996 for hydrogen production by steam–methane reforming was analyzed. For the simulated results of the first step, data from Hufton et al. (1999) and Ding and Alpay (2000) for a fixed‐bed column of an admixture of a catalyst and a sorbent that selectively removes CO2 from the reaction zone were used. The sorbent is periodically regenerated by using the principles of pressure‐swing adsorption. The process steps allow direct production of hydrogen with high purity and high methane conversion. A model considering multicomponent and overall mass balance, Ergun relation for pressure drop, energy balance for the bed‐volume element, and nonlinear adsorption equilibrium isotherm coupled with three main reactions was derived to describe the sorption‐enhanced reaction cyclic process. Two different isotherms were used under wet and dry conditions. The LDF model adopted describes the mass‐transfer rate of CO2 in the adsorbent. Numerical solution of model equations for the cyclic process was obtained by the orthogonal collocation method. The operating conditions allow the combination of a sufficiently high purity of hydrogen (average purity over 80%) with traces of CO and CO2, high methane conversion, fast adsorbent regeneration, and cyclic steady‐state operation. The model predictions agree reasonably with the literature data. The package is suitable for the design and analysis of sorption‐enhanced reaction process.