Working Principle of Ladle Refining Furnace
The ladle refining furnace is a device that refines in a ladle after tapping into an electric furnace or a converter.
The ladle refining furnace is composed of ladle, furnace cover, electrode heating system, and argon stirring system. The molten steel is stirred by blowing argon gas through the permeable brick installed at the bottom of the ladle to complete the reaction between steel and slag.
The function of the furnace cover is to close the refining chamber to maintain the reducing atmosphere.
Three-phase electrodes are used to make slag and increase the temperature of molten steel by arc heating, and a sliding nozzle is installed at the bottom of the ladle for pouring.
Equipment composition: ladle, ladle car, heating bridge and furnace cover lifting mechanism, water-cooled furnace cover, electrode lifting system, short net, argon gas, compressed air, water cooling system, hydraulic station, transformer, low-voltage control system, high-voltage system
The electric arc heating system used in ladle refining is the same as the steelmaking electric arc furnace. The arc generated between the three graphite electrodes and the slag molten steel is used as the heat source. The heating equipment is basically the same as the electric furnace. The difference is that there is no melting process in the LF furnace. The submerged arc heating method is used, so compared with the electric furnace, a lower secondary voltage and the smallest possible polar center can be used, and the submerged arc heating method has a protective effect on the furnace lining due to the small radiant heat. The thermal efficiency of heating is also relatively high, and the heat utilization rate is good.
The secondary side of the transformer used in the ladle refining furnace is usually divided into several levels of voltage, but it is not necessary to carry out on-load adjustment, so the equipment is relatively simple and the reliability is good.
When the ladle refining furnace is refining, the molten steel level is relatively stable, the current fluctuation is small, and there is no short-circuit impulse current caused by the collapse of the material when the electric furnace melts the charge, so the current density can be selected to be larger.
The adjustment system of the ladle refining furnace must have an automatic adjustment system with high sensitivity to reduce and prevent the carbon increase caused by the contact between the electrode and the molten steel.
The ladle refining furnace has the functions of arc heating under normal pressure, bottom-blowing argon stirring, temperature measurement, and sampling fine-tuning of alloy composition, deoxidation, desulfurization to remove impurities, etc., so as to obtain molten steel with high purity.