What is the difference between a power frequency induction furnace and a medium frequency induction furnace?

First, power frequency induction furnace

The power frequency induction furnace is an induction furnace that uses a current of industrial frequency (50 or 60 Hz) as a power source. The power frequency induction furnace has been developed into a smelting equipment with a wide range of uses. It is mainly used as a melting furnace for smelting gray cast iron, malleable cast iron, ductile iron and alloy cast iron. In addition, it is also used as a holding furnace. As before, the power frequency induction furnace has replaced the cupola as the main equipment for casting production. Compared with the cupola, the power frequency induction furnace has the composition of molten iron and temperature, and the gas in the casting is easy to control. There are many advantages such as low inclusions, no pollution to the environment, energy conservation and improved working conditions. Therefore, in recent years, the power frequency induction furnace has been rapidly developed.

The power frequency induction furnace complete set of equipment includes four parts.

1. Furnace part

The part of the power frequency induction furnace of the smelting cast iron is composed of an induction furnace (two units, one for smelting and another for standby), a furnace cover, a furnace frame, a tilting cylinder, and a moving lid opening and closing device.

2. Electrical parts

The electrical part consists of a power transformer, a main contactor, a balanced reactor, a balancing capacitor, a compensation capacitor, and an electrical console.

3. Cooling system

Cooling water systems include capacitor cooling, inductor cooling, and soft cable cooling. The cooling water system is composed of a water pump, a circulating pool or a cooling tower, and a pipeline valve.

4. Hydraulic system

Hydraulic systems include fuel tanks, oil pumps, oil pump motors, hydraulic system piping and valves, and hydraulic consoles.

Second, the intermediate frequency induction furnace

Induction furnaces with medium frequency induction furnaces with a power frequency in the range of 150 to 10,000 Hz are called intermediate frequency induction furnaces, and their main frequencies are in the range of 150 to 2500 Hz. Domestic small frequency induction furnace power supply frequency is 150, 1000 and 2500 Hz.

The medium frequency induction furnace is a special equipment suitable for smelting high quality steel and alloy. Compared with the power frequency induction furnace, it has the following advantages:

1) Fast melting speed and high production efficiency. The power density of the medium frequency induction furnace is large, and the power configuration per ton of molten steel is about 20-30% larger than that of the power frequency induction furnace. Therefore, under the same conditions, the medium frequency induction furnace has a high melting speed and high production efficiency.

2) Adaptability and flexible use. In the medium frequency induction furnace, the molten steel of each furnace can be completely cleaned, and it is convenient to replace the steel. However, the molten steel of the power frequency induction furnace is not allowed to be cleaned, and a part of the molten steel must be reserved for starting the furnace. Therefore, it is inconvenient to replace the steel, only applicable. Smelting a single type of steel.

3) Electromagnetic stirring effect is better. Since the electromagnetic force of the molten steel is inversely proportional to the square root of the power supply frequency, the stirring power of the intermediate frequency power supply is smaller than that of the commercial frequency power supply. For the removal of impurities and uniform chemical composition in steel, uniform temperature, the stirring effect of the intermediate frequency power supply is better. Excessive agitation of the power frequency power supply increases the flushing force of the molten steel to the lining, which not only reduces the refining effect but also reduces the life of the crucible.

4) Easy to start and operate. Since the skin effect of the intermediate frequency current is much larger than the power frequency current, the medium frequency induction furnace has no special requirements for the charge when starting, and can be heated quickly after charging; while the power frequency induction furnace requires a specially made open material block. (Approximately the cast steel or cast iron block, which is approximately the size of the crucible, which is about half the height of the crucible) can start the heating and the heating rate is very slow. Therefore, an intermediate frequency induction furnace is often used under the conditions of periodic operation. Another advantage of easy start-up is that it saves power during cycle operations.

Due to the above advantages, the medium frequency induction furnace has not only been widely used in the production of steel and alloys in recent years, but also in the production of cast iron, especially in the casting workshop of the cycle operation.

Auxiliary equipment for medium frequency induction furnace

The complete set of medium frequency induction furnace includes: power supply and electrical control part, furnace part, transmission and water cooling system.