Combustion Behaviors of Fine Coal and Its Impact on Gas Permeability at Lower Part of Blast Furnace under High Pulverized Coal Rate Operation

Practical ways of estimating temperatures of coke flowing into raceway as well as the gas core depth validated by direct measurement were suggested for the purpose of better describing the combustion behaviors of injected coal fine in blast furnace raceway. The numerical simulation model was refurnished with the scheme, and helped clarifying an intriguing effect of coal gasification or decomposition degrees before exiting tuyere tip on attained combustibility of coal at raceway boundary. Another scheme for quantitative expression of pressure losses caused exclusively by coal fine residence in and around raceway was also developed by shutting off coal injection for minutes at practical operation. The obtained results lead to developing the advanced tuyere, CD (converged and diverged) tuyere which enabled reducing the interaction between injectants and hot blast inside tuyere and thus improving overall gas permeability even under conditions of massive coal injection over 250 kg/tHM.