Three-Dimensional Simulation of Combustion Behaviour of Pulverised Coal Injection in A Blast Furnace

Abstract

Pulverized coal injection technology is widely used in blast furnace ironmaking due to economic, operational and environmental benefits. High burnout within the raceway is required for high coal injection rate operation. In order to analyze the flow and combustion in the tuyere and raceway, a three-dimensional model of coal combustion has been developed, considering details such as an inclined coaxial lance, three streams of different gases and various heterogeneous reactions of char particles. The model is first validated in connection with our previous study. The effects of coal properties and other typical operational parameters on the coal combustion efficiency are then investigated. The results indicate: (1) typical combustion and flow phenomena can be simulated successfully; (2) devolatilization plays a dominant role in coal combustion efficiency; (3) various measures for burnout improvements have been investigated and a linear dependence of overall burnout can be found for particle size distribution, volatile content and oxygen enrichment into the blast. Notable improvements in combustion efficiency are also obtained for coal with more fine particles and high volatile matter, and by increasing blast temperature and oxygen enrichment. The model offers a cost-effective method to examine the effects of variables related to different BF operations, which is useful for blast furnace design and control.