Force Balance in the Interior of the Blast Furnace

Abstract

The goal of this thesis is to advance knowledge about the balance of forces acting on granular materials in the interior of the blast furnace and on the walls. Using the principles of fluid and granular flows, a mathematical model is developed and used to generate new knowledge about the influence of process parameters, under control of the blast furnace operator, on the granular stress at the level of the gas inlet and the walls. The mathematical model developed is validated under ambient conditions by comparing predictions with experimental data obtained from physical scale models of the blast furnace. Comparison of the wall gas pressure profile from a commercial blast furnace with results from the mathematical model developed, indicate that gas temperature is an important factor in estimating the magnitude of the external force exerted by gas flow on granular materials. Results also show that the vertical stress acting on the upper boundary of the coke bed in the hearth can be altered by changing variables which are under the operator’s control. These variables include the gas properties (mass flow rate and pressure) and the properties of the granular column (bulk density of granular materials and cohesive zone location). Information generated in this thesis can be used by blast furnace operators for guidance in controlling the vertical stress at the upper boundary of the coke bed in the hearth and for defining the force at this boundary for subsequent studies of hearth region.