Assessments on SGG and WSGG spectral models in high-ash coal combustion

Abstract

In radiation process, a variety of models can be used to represent the spectral radiative properties of combustion gases. In coal combustion, the high level of soot concentration brings higher complexity to the formulation. Several pieces of research are found, comparing different radiation models usually applied to idealized laboratory situations. Only a few works explore the behavior of such models in real scale applications, such as coal-fired furnaces. Comparisons among different arrangements of the SGG and WSGG models were carried out by means of CFD simulations, applied to a boiler of a real 160 MW coal-fired power plant. Five different cases were simulated. The most simple case was set with a fixed absorption coefficient SGG model, while the most detailed case was achieved by employing a WSGG model with gas and soot absorption coefficients overlay. Temperature fields were well represented by all cases, with maximum deviations of 6%. Predictions on radiative heat flux for the SGG models were significantly lower than the WSGG simulations, with relative deviations up to 16.46%. Even though deviations on radiative heat flux are significant, results suggest the suitability of simple gray gas models in fast assessments of industrial applications such as coal-fired furnaces.