Thermal analysis and kinetic modeling of pulverized coal combustion accompanied with coke breeze

Abstract

Pulverized coal injection technique has been widely used as a means of reducing coke consumption during ironmaking process. Owing to the increasing shortage of fossil fuels, other substitutes such as biomass, plastic, and waste tires have been studied in recent years. Coke breeze as one of the by-products of coking industries has been investigated as a substitute for partial pulverized coals. The combustion characteristics of blended fuels were estimated based on the flammability index C and the combustion characteristic index S. For different coke breeze additions, the combustion was divided into two stages, and the apparent kinetic parameters of the two stages were estimated by fitting the experimental data to the shrinkage reaction model and shrinkage diffusion model, respectively. Results showed that with the increase in coke breeze addition from 15% to 60%, the indexes C and S decrease, and the activation energy of the first stage remains almost constant, while that of the last stage increases from 16.89 up to 67.18 kJ mol⁻¹, which indicates that adding coke breeze decreases the combustion efficiency of pulverized coal. Comparing the combustion and kinetic parameters under different coke breeze addition conditions, the optimal addition amount is suggested to be within 15%.