Conceptual Analysis of a Cyclic Water Gas Shift Reactor

Abstract

The cyclic water gas shift reactor (CWGSR) is based on the repeated reduction of a fixed bed using a mixture of hydrogen and carbon monoxide and its subsequent oxidation with steam to produce pure hydrogen. The reactor is analyzed on a conceptual level using a spatially distributed, dynamic model. The model assumptions and the resulting model equations are presented, and important parameters are discussed. Simulation results show that the CWGSR reactor has a poor performance for co-flow configuration of the gases during reduction and oxidation phase, but the reverse-flow configuration seems to be a very attractive option. Parameter variation of the duration of the reduction phase indicates that especially short cycling times not only yield high energetic performance, but they also decrease thermal and morphological stress on the fixed bed material. In addition, the counter-flow CWGSR with short cycling times shows an inherent heat integration like in a Matros reactor, which opens attractive options for system integration of this reactor with other process steps. The behavior of the CWGSR is compared to a pressure swing adsorption reactor (PSA), which shows common features, but also significant differences between both types of cyclic fixed bed reactors.