Numerical study on processes of oxy-fuel combustion of coal-water slurry in the furnace chamber

To reduce the negative impact on the environment, there is a need to recycle harmful waste (waste industrial oils, worn car tires, oil sludge, filter cakes, etc.). The technology of flame-droplet combustion of slurry fuel (containing waste) is one of the most environmentally friendly, economically profitable and promising. A significant disadvantage of this type of fuel is its low reactivity and unstable combustion due to its high water content. A solution to this problem can be oxy-fuel combustion technology or combustion in an environment with a high oxygen concentration. An increase in the volumetric concentration of oxygen in the blast helps to reduce the ignition induction period of hydrocarbon fuels (gas, liquid and solid), intensify carbon char burnout and reduce NOx. In this work, a numerical study of the physicochemical processes of oxy-fuel combustion of coal-water slurry in a furnace chamber with a power of 300 kW was carried out. The developed numerical technique was tested on experimental data on oxy-fuel combustion of CWS. The dependence of fuel atomization parameters, flame formation, carbon burnout rate, heat losses on oxygen concentration in the blast and moisture content in the fuel was studied. Reducing the oxygen concentration in the blast from 100 % to 50 % leads to a twofold decrease in the maximum rate of the kinetic reaction of oxidation of volatile components in the torch area. An increase in oxygen concentration from 50 % to 75 % leads to an increase in the burnout rate of solid carbon of a single particle on average from 0.00055 g/s to 0.00065 g/s in the flame zone. It was found that different moisture content in the fuel affects the period of ignition induction, but does not affect the rate of carbon burnout in the furnace chamber volume.