Modeling of fuel combustion in boilers of large and small capacity to reduce the toxicity of combustion products

Abstract

The issues related to the emission of atmospheric pollutants during the provision of energy supply services and the circulation of household waste in settlements are considered. The ways of air pollution of the residential area with toxic compounds, which are form by the existing methods of heat treatment of waste and during the operation of individual sources of heat supply for residential buildings, are analyzed. The issues of reducing the content of toxic emissions in combustion products are studied based on a numerical experiment using Computational Fluid Dynamics (CFD). Furnace processes in the energy boiler TP-14A (E 220/100) and the individual hot water boiler Vitocrossal 200 VIESSMANN are considered. The appropriate boundary conditions for the processes of aerodynamics, heat exchange and combustion of gas fuel have been defined. Numerical researches were carried out based on the Reynolds-averaged Navier-Stokes equations (RANS), with the closure of the equations using the two-parameter k-ε model. The combustion process was modeled as the transport of reactants Species Transport. The combustion calculations were performed using the Eddy-dissipation model. The scheme of a one-stage oxidation reaction to the final products of CO2 and H2O, the initial gaseous fuel — methane for the VIESSMANN Vitocrossal 200 boiler, and the products of coal dust gasification for the TP-14A boiler was used. The temperature, velocity and concentration fields in the boiler fireboxes have been determined. Based on the results of the calculations performed, the formation of chemical underburning and nitrogen oxides is predicted. The possibilities of numerical modeling of such processes are shown based on new directions in Chemkin modeling technology and the application of the ISAT algorithm. It is noted that they are also promising for modeling the kinetics of combustion processes using household waste as a fuel, but in this area of research, their application is still strongly limited by the computing power of available processors.