Effect of the mode of heat withdrawal on the asymmetry of temperature profiles in reverse-flow reactors. Catalytic combustion of methane as a test case

Results of simulations are presented concerning a reverse-flow reactor for the catalytic combustion of methane that occurs in coal-mine ventilation air. Two variants of heat withdrawal are analysed. The simulations show that a relation exists between the method for heat withdrawal and the asymmetry in the profiles of the catalyst temperature over half-cycles of flow reversal. Too strong asymmetry impairs the efficient utilization of the heat produced. The results reveal that the recovery of heat by hot gas withdrawal from the central part of the reactor, and then, the introduction of the gas into a boiler wherein it is cooled to about 333 K (60 degrees C) guarantee more favourable symmetry of the half-cycle profiles and much better utilization conditions than the direct withdrawal of heat from the mid-section of the reactor (central cooling). (c) 2007 Elsevier Ltd. All rights reserved.