Energy & Fuels, Vol.27, No.10, 6295-6303, 2013
Evaluation of Cofiring Bioferment Residue with Coal at Different Proportions: Combustion Characteristics and Kinetics
Hazardous waste treatment facilities in China are in shortage. Co-firing hazardous waste with coal in industrial and utility boilers would be a near term, low cost, and low risk option. This work presents a thermogravimetric and kinetic analysis based study on bioferment residue (BR, hazardous waste), coal and their blends to understand their cocombustion characteristics at different proportions. Kinetic data are obtained using the Coats-Redfern method. The co-firing ratio for BR/coal in different combustion types is suggested. It is found that BR has a composition that favors combustion, although its combustion properties are not as good as that of coal. Co-firing BR with coal mainly consists of four stages. Reaction mechanisms vary with combustion stage and blending ratio. BR-coal blends present a sum reactivity of their parent component. With increasing BR cofiring ratio, ignition temperature, and combustion rate basically decrease as well as the total energy output. Provided sufficient reaction time, BR, coal and their blends would be completely burnt below a temperature of 750 degrees C. Co-firing BR in coal fired boilers preferably below percentage of 10.1-42.2% for grate, 90.7-100% for FB, and 3.1-86.3% for PF.