Numerical model of pulverised coal combustion using recirculated flue gases and oxygen injection

摘要

This work presents an algorithm created in order to solve a system of non-The present paper presents results of numerical simulations of a 2.5 MWth burner in the IFRF horizontal test furnace. Two different cases were considered from the APG2 trials, one for normal air firing conditions and another case with flue gas recirculation and oxygen injection. Due to the higher CO_2 molar fractions, the model for the radiation properties of gases were reviewed. The Spectral-Line-based Weighted-sum-of-gray-gases (SLW) model was compared with Leckner's and the wide band model. The last one was used to evaluate the potential contribution of CO to the absorption coefficient that is small, so the SLW model was adopted. The numerical simulations were carried out with three different numerical grids. While in the coarser one the internal recirculation zone is not well represented specially for the case with recirculated flue gases, the other two further refined grids produce similar results. Comparisons are presented for the main gas species and temperature. The agreement is fair and the model can represent the main modifications of the flame when changing from air firing to recirculated flue gases. The work presented is a first validation to use the numerical model to study the use of the technique with co-firing biomass with pulverised coal.