468825 Hotspot Mitigation in an Annular Microchannel Reactor (AMR) for Hydrogen and/or Syn Gas Production

Wednesday, November 16, 2016
Grand Ballroom B (Hilton San Francisco Union Square)
Holly Butcher1, Benjamin Wilhite2, Peter Bossard3 and Andy Kaldor3, (1)Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, (2)Texas A&M University, College Station, TX, (3)Power and Energy Inc, Ivyland, PA

The potential economic impact of a portable, modular and efficient technology for converting logistical fuels (e.g., natural gas, methanol or ammonia) into hydrogen on-site or in-the-field processing of natural gas to liquid fuels via syngas production is significant. Heat-exchanger microreactors provide novel process intensification routes through breakthrough heat transfer rates per reaction volume, enhancing the capacity and thermal efficiency of heat-transfer limited reactions including methane steam reforming or ammonia decomposition. In both applications, supplying heat from a separate combustion reaction (e.g., pairing methane steam reforming with methane combustion) promises autothermal operation for maximum portability.

This study focuses on a way to mitigate local hotspot formation when coupling methane steam reforming with catalytic methane combustion in a heat-exchanger microreactor. Previous studies have shown that the annular microchannel reactor (AMR), originally developed by Power + Energy, can be powered by catalytic combustion of methane achieving up to 67% overall thermal efficiency. However, hotspot formation was found to be an issue for catalyst stability. The addition of reforming catalyst to the inlet region of the AMR acts as a reaction heat sink providing hotspot control and adding further reforming capacity. Different catalyst thicknesses ranging from 30-60 microns were used and catalyst length ranged from 10-30 mm. The additional catalyst results in a temperature drop of over 100°C at the inner wall of the annulus, as well as lowering peak temperature in the reactor by over 70°C. Despite the temperature drop, the reactor performance is maintained.

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