Physicochemical Transformations of Mixed Fuels Based on Typical Coals and Wood upon Heating

Abstract

The thermal decomposition of the mixtures of two types of dispersed coals and shredded wood in a temperature range until the complete pyrolysis of the organic matter of both components at different concentrations was experimentally studied in order to evaluate the prospects of using these fuels as composite fuels for large- and small-scale power plants (combustion in the furnaces of steam and hot-water boilers). It was established that the joint thermal decomposition of a mixture of coal and wood particles leads to a significant change in the pyrolysis temperature range and the release of anthropogenic gases (sulfur and nitrogen oxides) in the case of the high-temperature heating of such a mixture based on lean coal. A similar effect, but on a much smaller scale, was detected for a mixture based on long-flame coal. A hypothesis on the mechanism of sequestering sulfur and nitrogen oxides on the thermal decomposition of a mixture of lean coal and wood particles as a result of the interaction of intermediate gaseous and solid products of coal and wood pyrolysis in a temperature range to 1000°C was formulated. The possibility of using a mixture of crushed coal and wood as fuel for steam and hot water boilers was substantiated. With a certain decrease in the energy characteristics of such fuels compared to homogeneous coals, the environmental and economic characteristics of fuel burning processes were significantly improved. It was shown that a significant synergistic effect of co-combustion of particles of coal and wood is achieved only in certain coals.