CFD modeling of plasma thermal reactor for waste treatment
Recently, thermal plasma process has been proved to be a viable technology for recovering energy and useful products from waste. The purpose of this work is to extend computational fluid dynamics (CFD) modeling to analyze and optimize design of industrial scale thermal plasma reactor for medical waste treatment. Overall technical review of plasma thermal waste treatment technology is provided. Plasma treatment of solid waste involves complex chemical and physical phenomena, such as pyrolysis, char gasication, gas phase reactions, solid-gas multiphase flow, turbulence, radiation heat transfer etc. The comprehensive modeling of these phenomena is an unreachable target. So, key approximations, based on experimental observations, are made in developing CFD model. The thermal plasma reactor numerical model is implemented in the framework of commercial CFD code, FLUENT 6.3. Steady state incompressible Navier-Stokes equations are solved for basic fluid flow and physical sub-models used are: standard 2-eqn k-ε turbulence model, species transport with eddy dissipation kinetic model for gas phase reactions, P-1 model for radiation heat transfer and functional group approach with Arrhenius formulation for solid waste gasification. For non-transferred plasma jet, analytical model developed by  is employed. FLUENT model is developed for transferred plasma arc through user-defined functions (UDF), but it is avoided in reactor simulations for simplification. Numerical model is validated against experimental observations and then used in performance evaluation of different geometries of thermal plasma reactor. It is demonstrated that CFD model can be used for design analysis and optimization of thermal plasma reactor for waste treatment.
Frankel, Purdue University.
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