Combustion Characteristics Of The Coke Dry Quenching Ash And Pine Sawdust As Blast Auxiliary Fuel Injection

By the mean of blast furnace injection technology, the coke dry quenching ash and pine sawdust as blast auxiliary fuel for injection, which not only can reduce the cost of the blast furnace production, but also achieve reasonable comprehensive disposal and utilization of the coke dry quenching ash and pine sawdust, achieves the energy conservation and emissions reduction. In this paper, based on the physical and chemical properties of the coke dry quenching ash, pine sawdust, anthracite, and bituminous coal for blast furnace injection, thermal gravimetric analysis method used to study the combustion characteristics and combustion mechanism. The influence of heating rate and the mixing ratio on the combustion characteristics have been analyzed. The Flynn-Wall-Ozawa and Coats-Redfern models used to analysis the kinetics of the co-combustion process.The results show that, during the main combustion process, DTG curve exhibits a single peak for the coke dry quenching ash combustion process, while two peaks for bituminous coal. The DTG curves of pine sawdust appears volatile combustion peak and coke combustion peak, while one combustion peak for anthracite.The ignition and burnout temperatures of bituminous coal are lower than coke dry quenching ash, while the combustible index and comprehensive combustion index of bituminous coal were higher than the coke dry quenching ash. When the coke dry quenching ash content in the blends increased, the ignition temperature and burnout temperatures of the blends gradually decreased, while the flammability index and composite index of the blends gradually increased, the TG curves of the blends gradually turn to the lower temperature zone. When the heating rate increased, the intensity of combustion reaction gradually decreased, combustion reaction occur thermal hysteresis effect.The ignition and burnout temperatures of pine sawdust are lower than anthracite, but the combustible index and comprehensive combustion index of pine sawdust higher than anthracite. During the co-combustion of the blends, the main combustion process divided into two stages, volatile combustion stage and coke combustion stage, individually. With the content of pine sawdust increased, the TG curves gradually moved to lower temperature ozone, and the volatile peaks gradually strengthen, coke combustion peak gradually weakened, the ignition temperature and burnout temperatures of the blends gradually decreased, while the combustible index and comprehensive combustion index of the blends gradually increased. The present of pine sawdust can promote the combustion property of anthracite.Combustion kinetics analysis results showed that, during the co-combustion of coke dry quenching ash and bituminous coal, with the ratio of coke dry quenching ash increase, the apparent activation energy of coke combustion stage gradually decreased, Coats-Redfern model is more suitable for the analysis of two-peaks combustion process;. While the co-combustion of pine sawdust and anthracite, the apparent activation energy of volatile combustion stage and coke combustion stage gradually decreased, respectively, Flynn-Wall-Ozawa model is more suitable for the analysis of single peak combustion process.