Evaluation and discussion on the circumferential distribution of hot blast in the blast furnace

Abstract

The hot blast distribution has a great effect on the smooth operation of the blast furnace (BF). The standard deviation of blast volume of every tuyere (SD-BVT) is generally considered as an indicator for evaluating the uniformity of hot blast distribution. Based on the simulation, under the condition that all tuyeres have the same diameter, four circumferential symmetrical areas with large blast volume appear at 0, 90, 180 and 270 deg in Ansteel No. 1 BF, the value of SD-BVT is 1.32. In order to improve the uniformity of hot blast distribution, the diameter of the tuyeres with the largest blast volume in these four areas is reduced by 5 mm in actual production, the value of SD-BVT is changed to 3.24, which indicates that the uniformity of blast volume distribution is deteriorated, and this result is inconsistent with actual production. The oxygen in hot blast reacts with the coke in front of tuyere to produce carbon monoxide, which determines the coke consumption rate in the BF. As the hot blast distribution is non-uniform, the burden height is varied in the BF. So, according to the four areas with large blast volume and four areas with small blast volume in the BF, the BF is divided into eight areas and the standard deviation of areal burden height (SD-ABH) is used to evaluate the hot blast distribution. The calculation results show that, the value of SD-ABH is 0.41 under the tuyeres have the same diameter, but the value of SD-ABH reduced to 0.33 in actual production, indicating a 20% increase in the uniformity of areal burden height. This result confirms the reasonableness of the on-site operation and demonstrates the effectiveness of this method.