Computational fluid dynamics study of the effect of catalyst segmentation on the efficiency and performance of autothermal reformers for hydrogen production

Abstract

Improvements in autothermal steam reforming reactors would be highly beneficial to the production of hydrogen. The design of the reactors may be optimized by reducing catalyst requirements while effectively increasing catalyst’s efficiency. The present study relates to a catalytic process of steam–methanol reforming for the production of hydrogen in an autothermal heterogeneous reaction system. Various catalyst segmentation methods are employed to maximize product yields and minimize the amount of the catalyst. Computations were carried out with respect to various factors pertaining to catalyst segments, such as length, number, thickness, and loading. The effects of various segmentation methods and key parameters on reaction and transport processes are investigated in terms of performance and efficiency. Design recommendations are made to improve overall reaction rates and yields. The results indicated that the factors pertaining to catalyst segments are fundamentally important. A desired level of reactor performance can be maintained through the use of catalyst segmentation, while reducing the amount of the reforming catalyst by half or more. However, to ensure the effectiveness of catalyst segmentation, the number of catalyst segments must be sufficiently large and the thermal conductivity of the walls must be sufficiently high. The thickness of catalyst segments can be tailored to avoid the limitations imposed by chemical kinetics. The parallel flow design is more effective than the counter flow design. The loading of the catalytically active material significantly affects the performance of the reactor.