Induction furnace working equipment
Induction furnaces can be divided into core and coreless. Core induction furnaces are rarely used in steelmaking and are not described here. For coreless induction furnaces, induction furnaces can usually be divided into three types according to the power frequency: power frequency furnace (frequency 50 or 60 Hz), directly connected to the grid through transformers, mainly used for melting cast iron; high frequency furnace (frequency 10KHz ~ 300KHz), the power supply used is high-frequency tube oscillator, mainly used for small laboratory research; medium frequency furnace (frequency 150Hz ~ 10000Hz), the power supply used is medium frequency generator set, triple frequency frequency or thyristor static frequency converter.
The complete set of medium frequency induction furnace includes: power supply and electrical control part, furnace part, transmission and water cooling system
Characteristics of induction furnace melting
(1) Electromagnetic induction heating. Due to the different heating methods, the induction furnace has no graphite electrode necessary for arc heating, and there is no local overheating zone under the arc, thus eliminating the possibility of carbon addition of the electrode. Induction furnaces can smelt steels and alloys with extremely low carbon content that are difficult to smelt in electric arc furnaces, creating favorable conditions for obtaining products with low gas content.
(2) There is a certain intensity of electromagnetic stirring in the molten pool. The metal stirring promotes the composition and temperature uniformity caused by electromagnetic induction, and the inclusions in the steel merge, grow and float. Induction furnace melting has less alloying elements, so the predicted composition is more accurate, which is beneficial to component control and shortening of melting time.
(3) The specific surface area of the molten pool is small. This is advantageous for reducing the loss of easily oxidizable elements in the molten metal bath and reducing the suction, so the induction furnace is a relatively good condition for melting high alloy steels and alloys, especially those containing elements such as titanium, aluminum or boron. . However, it is easy to form poor fluidity and low reaction force, which is not conducive to the "cold slag" of the metallurgical reaction of the slag steel interface. For this reason, induction furnace smelting has strict requirements on raw materials.
(4) Input power adjustment is convenient. The input power can be easily adjusted during the induction furnace smelting process. Therefore, the temperature of the molten pool can be controlled more accurately, and the steel can be insulated in the furnace, and the steel can be tapped several times to create conditions for melting a plurality of products of different compositions in one furnace.
(5) The same power supply can supply power to several different capacity furnaces (but not at the same time), so the induction furnace has greater flexibility than the electric arc furnace in terms of smelting capacity.
(6) High thermal efficiency. The heating method of the induction furnace and the specific surface area are small, and the heat dissipation is small, so the thermal efficiency of the induction furnace is higher than that of the electric arc furnace. However, the electrical efficiency of the induction furnace is lower than that of the electric arc furnace, so the total efficiency of the two electric furnaces is similar.
(7) Less smoke and less pollution to the environment. When the induction furnace is smelted, there is substantially no flame and no combustion products.
(8) The consumption of refractory material is higher than that of electric arc furnace, and the life of crucible is short. The requirements for refractory materials are high, so the cost of refractory materials per ton of steel is also higher than that of electric arc furnaces.
