Analysis of design variables for water-gas-shift reactors by model-based optimization

Abstract

This work analyzes the water-gas-shift reactor design as component of the CO clean-up system of the ethanol processor for H2 production applied to PEM fuel cells. The WGS reactor constitutes the element of greater volume of the processor motivating its optimization. A model-based reactor optimization for different reactor configurations permits to obtain both designs for reducing volumes and optimal operating conditions. The heterogeneous model used allows computing the optimal reactor length and diameter, and the optimal catalyst particle diameter. The model computes the constraints required for catalyst, such as maximum and minimum operation temperature. The volume is sensitive to the CO outlet concentration. According to the required CO conversion it is necessary more than one reactor unit for the case study analyzed. When considering the insulating material, there exists an optimal thickness that affects the final volume and the design variables. These results are useful for estimating the minimum and relative sizes that allows conventional reactor technology. Several reactors configurations are analyzed in order to state the limiting values of the main design variables. Specially, insulation conditions are studied in detail to access minimum total volumes.