Modelling of CO2, CO, SO2, O2 and NOx emissions from the oxy-fuel combustion in a circulating fluidized bed

The paper presents a model of coal combustion in air and oxygen-enriched CFB environment. A computer program to calculate the CO2, CO, SO2, NOx and O-2 emissions from the combustion of solid fuels in a circulating fluidized bed boiler was created. The validity of this program was verified by measurements on a 0.1MW(th) OxyFuel-CFB Test Rig. The calculations have been carried out for air and so-called oxy-fuel conditions, i.e. when combustion runs in a gas mixture based on O-2 and N-2, with various fractions of oxygen. The comparison between measured and predicted by model CO, SO2, NOx and O-2 emissions is shown in this paper. The results of the calculation showed, that the kinetic equations of some reaction have to be modified. Authors propose to use the reaction surface area instead of the specific internal surface area of char in rate constant formulas as the combustion nature changes from internal-kinetic to external-diffusion controlling regime. (C) 2010 Elsevier B.V. All rights reserved.