(79f) CFD Simulations of Coupled Endothermic and Exothermic Methane Steam Reforming and Combustion in an Annular Microchannel Reactor (AMR)

Authors: 
Butcher, H., Texas A&M University
Wilhite, B. A., Texas A&M University
Bossard, P., Power & Energy Inc.

Microreactors fulfill the critical need for scalable on-site hydrogen and/or syngas production from natural gas.  The coupling of the endothermic steam reforming of methane with the exothermic combustion of methane allows for stand-alone, self-sustaining operation.  The use of microreactors enable breakthroughs in capacity and performance due to order-of-magnitude improvements in heat transfer rates per reactor volume owing to reduced characteristic transport lengths.

This overall goal of this study is to test the efficacy of pairing steam reforming of methane with the catalytic combustion of methane in a heat exchanger microreactor.  This investigation was carried out using a computation fluid dynamic model of a novel annular microchannel reactor (AMR), originally developed by Power + Energy. Simulations assuming a perfectly thermally isolated wall of infinite thermal conductivity, such that the wall temperature remains isothermally perfect, predict overall thermal efficiencies up to 72.6%. When matching overall heat duties but allowing for finite wall conductivity, local deviations in temperature (i.e. hotspots) are assessed to determine comprehensive catalyst stability. Finally, the stability of microreactor operation is investigated in the presence of deviations in feed flow.