Combustion modeling of blended coal in a 300‐MW tangentially fired boiler using a two‐mixture‐fraction model

The combustion process in a 300-MW tangentially fired boiler furnace fired with a blended coal has been numerically simulated. The blended coal contains a low-quality bituminous coal and anthracite and it was injected into the furnace from different burner nozzles. In order to better capture the combustion characteristics, a two-mixture-fraction model has been developed to model the combustion process of each individual coal of the blend. The two mixture fractions were used to separately track the combustion processes of the two component coals to reveal the effect of the combustion of the two coals on the chemical reactions in local zones of the furnace. The sum of the two mixture fractions was used to calculate the gas-phase turbulent combustion. Temperature measurements in the furnace were carried out by a flame image processing technique for model validation. Simulation results show that the temperature and oxygen concentration on the horizontal cross-sections close to the primary air burner nozzles in the furnace are nonuniformly, but symmetrically distributed across the four corners. The temperatures predicted by the simulation agree well with those measured by the flame image processing technique with a maximum error of 8.65%. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.