LES OF PULVERIZED COAL COMBUSTION FURNACES

摘要

LES (large eddy simulation) is applied to combustion simulations of two large scale pulverized coal-fired furnaces. One application is a boiler furnace with the coal feed rate of 3,000 kg/h. The results of LES show good agreement in not only distributions of temperature, NO concentration, and CO concentration on the vertical center line but also NO and CO emissions and UBC (unburned carbon in ash). The calculation error of NO emission is 10%. The other application is a horizontal furnace with a low NO_x burner with the coal feed rate of 560 kg/h. LES predicts temperatures and oxygen concentrations accurately; but the standard k-e model does not. The flame width calculated by the standard k-e model is narrower than that by LES. These calculated results indicate that the drawback of the standard k-e model is its low calculation accuracy for the coal jet flame decay and lift-off height.