Experimental investigation for the combustion characteristics of blends of three kinds of coal

The uneven distribution of coal resources coupled with changes in coal market prices in China have led many power plants to adopt blended coal combustion technology. Because of the varying combustion characteristics of the blended coals, it is necessary to study the combustion characteristics of the blended coals. In this study, blended coal were produced between the bituminous coals, Nanning meager-lean coals and petroleum coke, according to the mass percentages and particle size combination. A thermogravimetric analyzer is used to investigate the combustion characteristics and kinetic parameters of blended coals of three raw coals under different conditions. The experimental results show that the thermogravimetric curves of the blended coals with different blending ratios are between the thermogravimetric curves of bituminous coal and petroleum coke. Additionally, the blended coal with petroleum coke content at 30% has the optimal combustion performance, but the combustion characteristics of the blended coals deteriorate drastically when the percentage of petroleum coke in the blended coal increases to more than 30%. Kinetic analysis indicates that the activation energy of the stage before 500 degrees C is higher than that of the stage after 500 degrees C. As the oxygen concentration increases, nevertheless the mean activation energy of the sample is increased. Besides, the mean activation energy of blended coals shows that the combustion characteristics of blended coals cannot be determined solely by the activation energy derived from the Coats-Redfern method.