CFD Simulations of the Coal-Biomass Co-Firing Process in Pilot-Scale Pulverized Coal-Fired Furnace

Co-firing coal with biomass stands out as a promising and sustainable renewable energy option. In this paper, a numerical comparative analysis between coal firing and coal-biomass co-firing was conducted. A Computational Fluid Dynamic (CFD) model was developed to describe the combustion process inside a pilot-scale pulverized coal-fired furnace. The simulations for pure coal firing were performed for different rotation angles of the swirl generator, corresponding to the variation of swirl intensities. The results highlighted a strong influence of the rotation angle on flame shape. A rotation angle of 10 degrees is chosen to minimize SO2 generation inside the furnace and to prevent direct contact between the flame and the top furnace wall. Afterward, the CFD simulations for coal-biomass co-firing where the biomass ratio varies from 10% to 30% are performed. The numerical results show a noteworthy reduction in pollution gases generated during the combustion process. The SO2 and NO mass fractions at the outlet of the furnace can be reduced around 1.4 to 4 times indicating the advances of co-firing technology.