Numerical investigation of burden distribution in ironmaking blast furnace

Abstract

The control of burden distribution at blast furnace (BF) top is of paramount importance and mostly practiced in daily operations. However, to date, an effective method for optimizing top burden distribution under different conditions is yet unavailable. This paper presents a numerical method to achieve this goal using a well-developed and validated multi-fluid BF process model. The model simulates the BF region between burden surface and slag surface. First, a study of top burden distributions confirms that a uniform ore-to-coke distribution presents the highest process efficiency but a sharp pressure drop across the cohesive zone (CZ), which can lead to unstable production. Then, a top burden optimization method is proposed and tested. This is done by loading more coke to the central area while keeping uniformity in other areas. This burden control method decreases the in-furnace pressure drop significantly. When the coke charged into the central area is controlled properly, the gas flow there can be reasonably developed, and the process efficiency shows comparable to that of uniform burden distribution. These results are analyzed in terms of in-furnace flow, heat and mass transfer. Finally, as an example, a method to achieve the simulated optimum burden is proposed for use in a BF operation. This is done by use of DEM model simulating the flow of particle from the rotating chute into the throat in a BF top. This optimization methodology is considered applicable to other BFs.