Induction Furnace Power Usage

Induction Furnace Intermediate Frequency Power Supply

a. The power density configuration of the induction furnace is high or low. The configuration is high, the melting speed is fast, and the energy-saving effect is good, with low induction furnace power usage. Whether the electric furnace can maintain a high power factor to send electricity to the furnace is also the difference between high and low energy consumption.

b. The efficiency of the induction melting furnace and the electrical efficiency of the induction coil. (The total efficiency of foreign advanced induction furnaces is as high as 75%, and the induction coil is as high as 85%, while domestic ones are 73% and 80% respectively).

c. The conversion efficiency of intermediate frequency power supply is high or low. It reaches 97%-98% in foreign countries, and close to 97% in China, mainly in the efficiency of reactance and capacitance.

d. The layout of the electric furnace unit. The distance between the power supply and the furnace body, the length of the power transmission copper bar, the length of the water-cooling cable, and the distance between the power supply input voltage and the high-voltage transformer and the power supply point are all influencing factors.

Influence of Induction Furnace Melt

1) The cleanliness of the charged surface (if there are 5% impurities, 5% electric energy to melt these impurities) will also affect the life of the furnace lining.

2) Whether the length of the charge block is appropriate or not will affect the electric efficiency and melting quality of the electric furnace. Generally, a block size of 200-300mm is appropriate.

3) Whether there is liquid metal liquid in the furnace at the time of melting. It is advisable for the raffinate to account for 15% of the furnace capacity. If it is too small, the overheating of this part of the molten iron will be aggravated. If it is too large, the effective use of molten iron will be reduced and the induction furnace power usage will be increased. The emptying of molten iron reduces the power factor and the melting speed during use.

Induction Furnace Refractories

1) Reasonable thermal surface material thickness. Increasing the melting rate can reduce its thickness, but the service life is reduced, the cost of furnace construction is increased, and the safety hazard is increased.

2) Correct bottom thickness also affects induction furnace power usage of electrical efficiency and lining life. When the furnace bottom height exceeds the effective coil by 100mm, the bottom refractory material will strongly wash the bottom due to the induction stirring force, which will drastically reduce the service life.

3) The correct backing material is used. The isolation material is called backing material (such as asbestos cloth, etc.).

Disadvantages of using asbestos cloth as a backing material: people inhale it and stay in the lungs, which is carcinogenic; asbestos cloth generally contains high moisture, and it is easy to enter the quartz sand behind the quartz sand with water after a period of use, causing hardening and cracking.

The function of the backing material is insulation, waterproofing, and fire resistance of the inductor coil, and the surface of the cement serves as an isolation function and facilitates the replacement of the furnace lining. Behind the hot side of the quartz sand, we hope that there is a loose layer so that the molten iron will stop here if it drills through the hot side.

The cooling water temperature of the sensor is a necessary condition for creating a loose layer.

If you use an asbestos cloth with good heat insulation and add water, the trace amount of boric acid in the quartz sand will harden it, and mica paper is the best choice.

Treated with high-grade coil cement, the surface is smooth, no need to use backing materials, but it must have the properties of easy processing, no cracks after drying, and no reaction with acidic substances.

Induction Furnaces Energy Savings During Operation of Induction Melting Furnaces

Dosing timing. The amount of solid furnace material added for the first time should reach about 1/3 of the furnace capacity, otherwise, it will affect the power output, and will also spark (discharge) arc and consume electricity, and may cause cracks on the surface of the furnace lining, which is a neutral material for cast steel Great damage.

When the first batch of material reaches the molten state, the solid furnace material sinks, and the material should be continued immediately at this time, which can melt the softened solid material under pressure so that the melting can proceed at the fastest speed.

It is normal to feed the furnace without violent tumbling in the liquid state (violent tumbling in the liquid state means that the molten metal is overheated and scours the furnace wall, consuming the lining material).

This requires that the power input of the melting time is less than 20% (first feeding) → 50% (softening) → 65% (feeding) → 100% feeding – to reach the temperature required by the process. Then power off the liquid.

Induction furnace avoids high energy consumption due to improper operation

a. The molten metal is overheated.

b. The liquid is discharged without stopping the induction furnace. Not only unsafe but also wrong in terms of energy consumption and melting process. Generally, the electric furnace inductor is divided into upper and lower parts.

When the molten metal level in the furnace is lower than half of the upper inductor, due to the change of resistance, the upper inductor no longer has induced current passing through, and all of it is concentrated in the lower inductor, so that the lower molten metal overheating, washing the furnace wall, and the service life of the furnace lining will drop sharply.

c. High-temperature insulation. The long-term high temperatures will change the metallographic phase, C and Si phase transformation, the whitening tendency of the casting is serious, and the machinability will deteriorate.