Recovery of waste-derived and low-grade components within fuel slurries

The article considers the involvement of combustible waste in the energy sector as the main and additional components of slurry fuels for burning in boilers. Five compositions of waste-derived slurries have been developed based on the analysis of ignition and combustion characteristics of nine components. For these compositions, the values of ignition delay, minimum ignition temperature, maximum burning temperature, SOx and NOx concentrations have been determined. The efficiency indicators of the slurries have been calculated in comparison with coal and fuel oil. The relative values take into account combustion heat, cost, ash content, ignition delay, minimum ignition temperature, maximum combustion temperature, and emissions. The most attractive fuel has been identified: 20 wt% of coal slime, 30 wt% of coal flotation waste, 40 wt% of wastewater, and 10 wt% of peat. On the aggregate indicator, this fuel surpasses coal 2.11 times and fuel oil – 11.9 times. All investigated water-containing fuels turned out to be less dangerous on environmental indicators than coal dust. In particular, SOx and NOx emissions were 1.2–3.8 times lower in comparison with coal. Using the example of a typical coal-fired boiler, an assessment was made of the potential reduction in fuel purchase costs, as well as savings in water treatment. [Display omitted] •Using of wastes in water-slurries is more preferable compared to direct combustion.•When burning slurries, NOx and SOx are 20% lower 1.2–3.8 times than using coal.•Combustion heat of the studied slurries was 13–17 MJ/kg.•Relative efficiency of the slurries compared to coal and fuel oil reached 12.5•Coal-fired boiler can decrease fuel costs minimum by 20% using waste-derives slurries.