Entrained flow gasification. Part 2: Mathematical modeling of the gasifier using RANS method

CFD (RANS based) simulations of REGA-1 experimental campaign concerning gasification of glycol in an oxygen-nitrogen mixture have been carried out. The reacting flow-field has been computed using a number of turbulence models while turbulence-chemistry interactions have been modeled using either the Eddy Dissipation Concept (EDC) or the presumed PDF approach. Two global-chemistry schemes have been used: the (HVI1) scheme for glycol gasification and the extended Jones-Lindstedt scheme. Radiation has been computed using the Discrete Ordinate Method with a comprehensive analysis concerning absorption/emission of infrared radiation by gaseous molecules as well as absorption and scattering on droplets. The CFD-predictions of the near-atomizer region have been sensitive to and strongly dependent on the sub-models used; the spray sub-model and the chemical schemes are the most important. Good quality predictions of temperature and chemical species (CO,H2,CO2,H2O,CH4) concentrations at 300 mm and 680 mm distances from the atomizer have been obtained. The HVI1 global chemistry scheme has predicted very well not only the CO/CO2 ratios but also the trace concentrations of methane. The paper shows how to simplify the radiative heat transfer simulations without a significant loss in accuracy.