OPTIMIZATION OF THE SOLID FUEL COMBUSTION PROCESS IN COMBUSTION CHAMBERS IN ORDER TO REDUCE HARMFUL EMISSIONS

Abstract

The methods of numerical simulation are used to study the processes of heat and mass transfer in thecombustion chamber of an operating coal-burning Kazakhstan thermal power plant. Computational experiments wereperformed on the combustion of high-ash Karaganda coal in the combustion chamber of the BKZ-75 boiler(Shakhtinsk, Karaganda region). As a result of numerical simulation of the combustion processes, the distributions ofthe total velocity vector, temperature fields, concentration fields of nitrogen oxides NO over the entire volume of thecombustion chamber and at its exit were obtained. A comparative analysis of the characteristics of heat and masstransfer processes for the two studied modes of supplying fuel to the combustion chamber through burner devices isgiven for the direct-flow method of supplying the mixture when the burners are located on opposite side walls andthe vortex method of supplying the mixture when the burners are installed at a 30-degree angle from the center ofsymmetry of the boiler. It is shown that the vortex method of supplying air mixtures allows optimizing thecombustion of high-ash coal, since in this case there is an increase in temperature in the core of the torch and adecrease in it at the exit from the combustion chamber, which has a significant effect on the chemical processes ofthe formation of combustion products. The average value of the concentration of nitrogen oxide NO at the outlet ofthe combustion chamber decreases when using burner devices with a swirl of the mixture flow and conforms tonorms the maximum permissible concentration.