Effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals

This work reports the combustion characteristics of two high ash Indian coal, petroleum coke, rice husk, and their blends to assess the effect of rice husk and petroleum coke blending on combustion characteristics of high ash Indian coals. Based on the combustion data obtained from the thermogravimetric analysis, various burning profile parameters such as ignition temperature, burnout temperature, activation energy, and combustion efficiency were analyzed to identify the impacts of petroleum coke and rice husk blending on coal combustion. Results show that petroleum coke having 8602 kcal/kg gross calorific value but inferior combustion properties compared to coal and rice husk. For coal A blends with 10% petroleum coke, with the increase in rice husk content in blends from 10 to 40%, ignition temperature decreased from 409 to 270(O)C, burnout temperature dropped from 506 to 502(O)C, inferring significant improvements in combustion properties compared to coal and petroleum coke. For coal B blends with 10% petroleum coke, at 300(O)C with the increase in rice husk in blends from 10 to 40%, combustion efficiency increased from 4.84 to 19.21%. For 20% petroleum coke of coal B blends, with the increase in rice husk in blends from 10 to 30%, activation energy decreased from 82.54 to 57.69 kJ/mol. Synergistic analysis infers that blending of higher biomass promotes synergistic due to catalytic effect. Analysis of changes in enthalpy, Gibbs free energy and entropy implied that individual combustion of both coal and petroleum coke is difficult compared to rice husk, whereas blending of rice husk makes the combustion process significantly favorable.