Major gas emissions from combustion of slurry fuels based on coal, coal waste, and coal derivatives

This research experimentally determines the major gas emissions from the industrial combustion of coal, coal processing waste, and coal derivatives in the form of traditional coal dust as well as slurry fuels with water and flammable additives. Several types of coal are considered: gas coal, flame coal, bituminous, non-coking and low-caking coal, as well as coal processing waste (filter cakes), coal derivatives (coke, semi-coke), and flammable liquids (industrial oil waste, fuel oil). Experimental data for charcoal and carbon dust from recycled car tires are presented as well. The concentration is evaluated for the most hazardous gas emissions: sulfur and nitrogen oxides. A number of factors defining the said concentrations are established: the quality of components, their elemental composition and concentration (40-60% coal, 30-50% water, 5-15% flammable liquid); slurry preparation method (homogenizer or cavitator); coal grind (8-250 mu m); and the mass of the batch (0.5-1.5 g). In particular, changing coal concentration in a slurry from 40 to 60% increases the emission of nitrogen oxide by 35% and sulfur oxide by 67%. Varying water concentration from 30 to 50% decreases the emission of nitrogen oxide by 17% and sulfur oxide by 62%. Increasing the flammable liquid concentration from 5 to 15% slightly lowers the emission of nitrogen oxide (by 5%), while the sulfur oxide emission grows by 28%. The advantages of coal-water slurry containing petrochemicals combustion are identified over coal. Moreover, the main limitations are determined for large-scale usage of slurry fuels instead of traditional heat and power industry fuels. (C) 2017 Elsevier Ltd. All rights reserved.