According to the different characteristics of these two kinds of block furnaces, corresponding technological measures can be adopted to solve them.The gradual warming process of general block furnace. Full use of Thyristor Intermediate frequency furnace has the characteristics of heavy load starting. In the selection of initial power and the determination of the galvanization at each power stage, the expansion of the furnace lining should be fully considered, so that the expansion rate of the furnace lining is close to that of the steel block. When reaching the higher power section, the holding time of the power section should be prolonged, so that the cracks on the lining can be gradually reduced until they are completely disappeared, and then the heating power can be further increased.
Taking 250kg medium frequency furnace as an example, the material block in the furnace is ZG42SiMnCrMoTiRe.First of all, in order to make the lining temperature and the furnace temperature gradually uniform and increase, so as to achieve synchronous expansion, the initial power is selected as Z0kW. After 40 minutes, adjust the power to 40kW for 30 minutes. Then adjust the power to 80kW, and the power segment is maintained for 30 minutes. Continue to adjust the power to 110 kW, in this power section should pay close attention to the changes in the lining, the retention time is based on the lining cracks gradually narrowed, fully healed, until completely disappeared, the general retention time is more than 50 minutes. After the cracks on the lining have disappeared completely, the power can be continuously increased to 130kW, which can be maintained for about 30 minutes, and then can be directly raised to 160kW until the steel block in the furnace melts completely. The main points of operation are basically the same as those of ordinary furnace. The difference lies in the treatment of thick crusts at the mouth of the furnace. Taking 250kg coreless medium frequency induction furnace as an example, when the power rises to 110 kW, the lower part of the furnace has melted and the crust at the furnace mouth has not yet melted. Because of volume expansion and high temperature action, the high temperature molten steel in the lower part of the furnace erodes and erodes the furnace Village seriously. It is easy to wear through the furnace for a long time. Therefore, the furnace can be tilted to a certain angle, the crust can be partly melted by the high temperature molten steel in the lower part of the furnace, or the crust can be cut by the acetylene gas cutting gun, and the crust can be quickly pushed into the furnace to repair the damaged furnace mouth.
In general, the treatment process of the hearth furnace does not need to tilt back and forth during the whole melting process, so it can ensure that all parts of the lining are scoured and corroded by molten steel. Practice has proved that this process will not affect the service life of the lining. It is suitable for the hearth furnace in the first and middle period of the lining use.
Because of the long time tilting of the furnace during the whole melting process, some parts of the furnace lining have been eroded and eroded by molten steel for a long time, resulting in lining spalling and easy wearing, and the lining life has been greatly reduced after treatment. Therefore, this process is only suitable for solving the problem that the lining of the furnace occurred in the early stage (thick lining) to the middle and late stage of the furnace, because the lining is thin, it is not suitable to use this process. It is better to remove the lining and remove the metal blocks.
It is difficult to deal with the serious hearth furnace. Therefore, it is necessary to avoid the serious hearth furnace as far as possible in production, try to take out part of the molten steel in the furnace, and convert the serious hearth furnace into a general hearth furnace which is easy to handle.