SELECTION OF A FIXED BED SOLID FUEL COMBUSTION MODEL IN ANSYS FLUENT

The aim of the paper is to present approaches to the use of computer modelling of solid fuel combustion in a fixed bed in furnaces and boilers of small capacity. The principles of modelling solid fuel combustion in Ansys Fluent are considered. The method of calculation model construction for solid fuel combustion in a fixed layer in furnaces and boilers of small capacity is proposed. Since combustion is characterised by great complexity in modelling, in order to simplify the model, the fuel layer was not separated into a separate computational domain and was replaced by boundary conditions, and the computational domain contains only the gas part. In the model the fuel enters the calculation area corresponding to the gas part through the surface of the area limiting the solid fuel, combustion takes place at the boundary of solid and gas areas and in the form of heterogeneous combustion reaction of solid carbon and in the gas area in the form of gas-phase reactions of oxidation of CO and hydrocarbons of released volatile substances. Simplifications of the model are the absence of carry-over of unburned particles. The adequacy of combustion modelling is proposed to be checked by comparison of the modelling results with the results of fuel combustion calculation (composition of combustion products and temperature), content of harmful substances and analysis of combustion along the course of gas flow in the calculation area in the current lines.