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

摘要

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, H-2, 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.