Estimation of accident rate of blast furnace tuyeres

Abstract

In modern blast furnace production, even a short-term disruption of the technological process is associated with large productivity losses. In the practice of conducting blast furnace melting, there are often significant deviations from the optimal mode. They can lead not only to disruptions of the blast furnace, but also to accidents. In the operation of a blast furnace, typical deviations from the normal distribution of gas flow and charge materials include: peripheral, axial, channel passages; skewing of the backfill level; varying degrees and types of charge suspension. As a result, there are a cooling or excessive overheating of the furnace and violation of the melting operation. A serious consequence of the prolonged peripheral movement of gases is not only intensive wear of the lining, poor use of thermal and chemical energy of gases, but also stable cluttering of the hearth with formation of a deadman. Deadman is an ore-coke sinter formed in the tuyere zone of a blast furnace, as a result of cooling of its center. The paper describes the study and analysis of violations of blast furnace operation, analysis of the deadman causes and assessment of the accident rate of blast furnace tuyeres. Violation of gas distribution and hearth cluttering lead to formation of a deadman, which provokes mass burning of tuyeres and blast furnace refrigerators. The developed methodological foundations (mathematical model) allow us to estimate the maximum temperature of the tuyere zone and the resulting heat flow to the tuyere toe in presence of a deadman. It is shown that in large-volume blast furnaces, bubble outflow of the gas-coal flow prevails, contributing to growth of a deadman in the blast furnace.