Investigation the coal thermal characteristics influence on combustion process in the furnace

Abstract

The article presents the study results on the possibility of burning the bituminous coal instead the lignite in the boiler BKZ-420-140 type. The study objectives are to determine the influence of coals thermal characteristics on the combustion efficiency in a boiler. The boiler efficiency analysis when burning various coal types is carried out on the basis of fuel combustion process numerical simulation. The furnace process assessment was carried out according permissible mechanical unburning of solid fuel, absence of furnace walls slag, the flue gas temperature at the model outlet, the concentration of NOx in flue gases. The studies were carried out for bituminous coals with a change in the lower calorific value in the range from 14.61 to 25.62 MJ/kg. It was found that for most of the studied bituminous coals the unburned carbon loss does not exceed 0.5% (with the exception of Kuznetsk bituminous lean coal). It has been established that with an increase in the calorific value of the bituminous coal, the concentration of nitrogen oxides in the flue gases increases. There was no dependence of the concentration of nitrogen oxides on the lower calorific value found for low-volatile bituminous coals. The effect of bituminous coal humidity on the flue gas temperature at the furnace outlet and on the unburned carbon loss is ambiguous due to small changes.