Shutting Down Blast Furnace
The blast furnace is a key component of the steelmaking process, and its shut down is a complex and critical operation. Shutting down a blast furnace is not just about turning off some switches, taking a few readings and having a cup of tea. A major part of the process involves cooling down the furnace structure and refractories, or refractory lining, to an insulated and safe temperature, and it can take several days to complete.
The primary step in shutting down a blast furnace is to stop the supply of raw materials such as coke and ore. The furnace needs to be depleted as quickly as possible, before the materials harden and become more difficult to extract. Gas pressures, such as those in the blast burners, should also be reduced.
Once the furnace has been emptied, the temperature of the entire structure must be reduced until it is cool enough to open. Depending on the rate of temperature reduction and the size of the furnace, this process can take anywhere from several hours to several days.
Part of the cooling process involves refractory removal, which is the process of removing the refractory linings at the top and bottom of the furnace. This ensures that the furnace walls are not damaged by residual heat. The removed linings should be cooled and then inspected for wear or any other damage.
Finally, the furnace should be inspected for any damage that may have occurred during the shutdown or heating up process. This includes checking the integrity of the furnace seals and walls, and any components that may have been exposed to the high temperatures.
After the blast furnace has cooled down to a safe temperature and has been inspected, maintenance and repair work can begin. This includes inspecting, cleaning and repairing the furnace components, such as the tuyeres, lining and blower.
Shutting down a blast furnace is a complex and time-consuming process. The success of the operation depends on a thorough understanding of the process and on the maintenance staff being well trained and experienced. In addition, it is important that the furnace is cooled properly to avoid damage to the structure and subsequent costly repairs.
