Thermodynamic data for the efficient coupling of exothermic and endothermic reactions in autothermal reformers under moderate operating conditions
Description
The thermodynamic data are directed to a parallel reaction system, especially a chemical processing micro-system, which can simultaneously carry out exothermic and endothermic reactions in separate micro-channels and simultaneously adjust feed composition and flow rates. Specifically, the thermodynamic data relate to a catalytic process of steam-methanol reforming for the production of hydrogen in an autothermal reformer. To obtain the solution of the thermodynamic data problem, numerical simulations are performed using fluid mechanics. The ratio of the height of the channels to the width of the channels may vary. In the present study, the cross-sectional configuration of the channels is square. The channels are 0.7 millimeters in height and in width and 30.0 millimeters in length. Channel height refers to the inside height of a channel. To ensure the mechanical strength at elevated pressures, the thickness of the uncoated walls is 0.7 millimeters. The oxidation catalyst consists essentially of oxides of copper, zinc and aluminum. The oxidation catalyst allows for initial start-up and the heat-up of the reactor system. The reforming catalyst consists essentially of copper and oxides of zinc and aluminum. The exothermic and endothermic processes are conducted at a pressure of 0.8 megapascals, with a methanol-air equivalence ratio of 0.8 and a steam-to-methanol molar ratio of 1.17. The inlet temperature of the mixtures is 373 degrees Kelvin. The temperature of the reactor can be regulated by the balance of the flow rates so that the catalyst is not overheated by the exothermic process and thus damaged. To assure that adequate temperatures are provided for endothermic reforming, operating flow conditions are specified for the reactor by giving the gas velocity. The gas velocity is 2.0 meters per second at the reforming channel inlets and 0.6 meters per second at the oxidation channel inlets, thereby assuring sufficient heat in the reactor to carry out endothermic reforming of methanol. Contributor: Junjie Chen, E-mail address: koncjj@gmail.com, ORCID: 0000-0002-5022-6863, Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China
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Heterogeneous reactions at a catalytically active surface affect the heat and mass balance at the surface. In addition, surface reactions create sources and sinks of chemical species on the surface and in the gas phase. Consequently, chemical reactions involving surface species significantly influence the boundary conditions. The mass fluxes of gas-phase species at the phase boundaries are balanced by the production rates of gas-phase species by surface reactions. The heat release and consumption due to a surface reaction must be included in the model. Endothermicity or exothermicity of surface reactions contribute to the energy balance at an interface. Heat fluxes in the solid phase are balanced by chemical heat release at the surface.