SIMULATION OF GAS FLOW IN BLAST FURNACE FOR DIFFERENT BURDEN DISTRIBUTION AND COHESIVE ZONE SHAPE

Blast furnace is a very complex physico-chemical process with countercurrent flow of gas and solid. Computation of gas flow through different regions of blast furnace can be considered as the first major step towards numerical simulation of the process. Gas velocity profile in blast furnace depends on the burden distribution and shape of the cohesive zone, which affect the overall thermal efficiency and utilization of reduction potential of the gas (CO/CO2ratio). Nonuniform or high gas flow near the wall causes overheating of the wall, which leads to high rate of refractory erosion and heat loss. High gas flow through the central region, on the other hand, causes higher CO/CO2ratio at the center, leading to reduction in chemical and thermal efficiency of the gas. Therefore, achieving an optimum gas flow by controlling the burden distribution and shape of the cohesive zone is very important for minimizing refractory loss, thermal and chemical efficiency of the process. Gas velocity through various zones of blast furnace is computed by solving vectorial Ergun's equation for flow through porous medium considering axi-symmetric condition. To incorporate the shape of blast furnace efficiently, one-dimensional stretching in radial direction or nonorthogonal body-fitted coordinate system is used by the standard to transformation method. This model can be used for optimizing burden distribution and developing gas velocity control systems for blast furnace.