Kinetic and experimental analysis of the effect of particle size on combustion performance of low-rank coals

Low-rank coal resources are abundant, which is the key to realizing coal high-value utilization. This paper focused on the effect of particle size of low-rank coal on combustion performance by experiment and kinetic analysis, and proved the feasibility and safety of low-rank coal enlarged particle size for blast furnace injection. Form the research results, the explosive, combustion and gasification behavior of samples are related to its volatile content, the oxygen content, the specific surface area and the reactive sites in the coal. Safety is the key to realize the injection high-proportion or even all low-rank coal, and the increasing of particle size can effectively inhibit its explosive and reduce its combustibility. For low-rank coal with 25%-40%, d2 (0.074–0.150 mm) is an appropriate particle size for blast furnace injection, which ensures safety and better combustibility. Furthermore, there are differences in the heat and mass transfer process of different particle sizes during the combustion process by affecting its behaviors such as organic matter consumption and volatile matter removal. The apparent activation energy of coal decreases with the increase of volatile content and particle size.