Combustion stages of waste-derived blends burned as pellets, layers, and droplets of slurry

This paper describes the results of an experimental investigation on the stages of thermochemical transformation of fuels prepared from waste. We studied the combustion of coal slime and its co-combustion with additives (waste turbine oil, sawdust, and rapeseed oil). The mass fraction of the additive was 5%. Fuels in the forms of a pellet, dry loose layer, and slurry were heated in a tubular muffle furnace. The reactivity of the fuels was evaluated, and the duration of the main process stages was recorded. Experiments have shown that it is more expedient to burn coal slime in combination with other components, which improved the ignition and burnout performance of the blends. The addition of turbine oil accelerated the flame combustion by 3–6 times. Rapeseed oil reduced the duration of the endothermic stage by 50–60%. The slurry droplets had the longest pre-flame stage. Their burnout was more intense than that of pellets or a layer and was less dependent on the temperature in the furnace. The longest burnout was typical of pellets. The data obtained are essential in planning and conducting industrial tests on the energy recovery of coal slime, biomass, and refined products. [Display omitted] •Combustion of coal slime is advisable in combination with other components.•The burnout of slurry droplets is the best in comparison with pellets and layers.•The addition of turbine oil (5 wt%) reduced the endothermic period by 3–6 times.•Minimal ignition temperature of waste-derived blends varied from 450 °C to 500 °C.•Coal slime pellets tend to low reactivity and incomplete burnout.