CFD Simulation Of Water Gas Shift Reaction Catalyst

Catalyst is the core part of catalytic reactor, because of the porous structure of catalyst, the internal flow field, temperature field of catalyst is very complex, the research cycle is long, low efficiency to measure catalyst model by traditional experimental method. With the rapid development of computer technology and computational fluid dynamics(CFD), the numerical simulation offer a more effective new method for catalyst research.In this paper, a fixed bed reactor of water gas shift reaction as the object of study, from the assume of continuous medium point, conservation law as the theoretical basis, combine with the macro-dynamics of the chemical reaction, establish a universal mathematics model to describe the "three transfer and one reaction" of porous media. Since the mathematical model is nonlinear partial differential equations, and each equation is closely coupled, therefore discretized and solved by numerical methods, the mathematics model solved by finite volume method of FLUENT and finite element method of COMSOL in this paper. The main content as follows:1.Computational fluid dynamics(CFD) methods used to simulate interior reaction of catalyst, a two-dimensional heterogeneous reaction model coupled with low-temperature water gas shift reaction is established. FLUENT as the simulation platform, add solid-phase energy equation by UDS, one-temperature model of porous media is corrected to the gas-solid phase two-temperature model coupled heat transfer, add chemical reaction by source term, the chemical reaction heat is added to the gas-solid energy equation. Spalart-Allmaras equation as turbulence model, Langmuir-Hinshelwood equation as kinetic model, The properties of the catalyst and operating conditions based on the experiment of Wei-Hsin Chen. The finite volume method used to unsteady simulation, the model is solved by SIMPLE algorithm, visual analysis the component concentration field,the velocity field and temperature field in the reactor. Final, list the unsteady two-temperature model axial temperature profile at three time points, and were compared with the one-temperature model of literature, two-temperature model results is more correspond to actual model.2.COMSOL is used to sensitivity analysis of reactor catalytic condition. In the process of numerical simulation, one-temperature mathematical model of carbon monoxide water gas shift reaction is established, the specific heat capacity, viscosity, diffusion coefficient and thermal conductivity are computed by molecular dynamics theory. Apply finite element simulation to the model by COMSOL, obtained the temperature distribution, the concentration distribution, pressure distribution in the porous medium, and then the model was validated by experiment. On this basis, optimize the operating conditions of the model: followed by analysis the bed temperature distribution, CO conversion impacted by inlet temperature, catalyst activity, inlet components and inlet pressure. It turned out that:when catalyst is deactivation, it can improve activation of catalyst by changing inlet temperature of reactant to reduce loss; when activation reduce to0.5, it need to renewal catalyst.