Numerical analysis of thermo-fluid flow and chemical species in the lower part of a blast furnace considering change of cohesive zone

Abstract

A blast furnace is considered as a counter current type reactor where the blast gas flows upward while the packed bed of particles is slowly moving downward. The bed is consisted of a multiple of alternating layers of coke and iron ore. The particles of iron ore are heated up and chemically reduced until they change their phase into liquid. After passing through the cohesive zone, molten iron passes through the packed bed of coke particles which still undergoes oxidation. Lower part of a blast furnace is defined as a region under the cohesive zone, where liquid phase molten iron flows down through the packed bed of solid coke particles while blast gas from the tuyere flows upward. The increasing interest on minimizing fuel consumption and reducing environmental problems of the iron making industry has led to efforts to optimize the blast furnace process. One of the unexplored fields emerging from the adoption of new operating conditions is the internal phenomena in the lower part of the furnace following the change of cohesive zone shape. The effective flow in the dripping zone of a blast furnace is important for stable operation with high iron productivity. Study of the liquid flow behavior in a packed bed needs to investigate the effect of various operational changes in the dripping zone. In this research, mathematical formulations in the lower part of a blast furnace are derived for the gas, liquid and solid. Isothermal flow for three phases is simulated to understand flow and interaction among each phase. The results from the mathematical modeling include the radial distribution of velocity and mass flow rate. Coke size and viscosity which can change the porosity of the lower parts are used as parameters to analyze the basic results. And the results are simulated with the variation of the shape of cohesive zone to see the effect of the charging condition. After finishing the isothermal flow model, chemicals species and temperature distribution are also ...