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Home / How Does Induction Furnace for Steel Melting Save Energy?
How Does Induction Furnace for Steel Melting Save Energy?
2023.08.22
The induction furnace for steel melting has high efficiency, fast melting speed, less burning loss, less heat loss, relatively low workshop temperature, and less smoke and dust. It has remarkable effects in saving energy, increasing productivity, improving working conditions, reducing labor intensity, and purifying the workshop environment. However, the issue of energy saving in the production of induction furnaces has always been a concern for users. Below we summarize several ways to save electricity in the production of medium-frequency induction furnaces.
The power actually used for heating and melting in the induction furnace only accounts for 60% to 70%. The remaining 30% to 40% are lost in various forms. The components that cause loss mainly include power transformers, intermediate frequency power cabinets, copper bars, and water-cooled cables, as well as furnace linings and induction coils. Among them, the heat loss of the induction coil and the heat loss of a section of wire (water cable) between the compensation capacitor bank and the induction coil account for more than 20% of the total input power, and the thermal radiation of the furnace mouth and the conduction heat loss of the furnace body reach 10% of the total power. Therefore, rationally designing the induction coil and its feeder circuit, and adopting a high-voltage and large-tonnage design scheme can greatly save energy and increase the melting speed.
Is the voltage of the induction furnace for steel melting as high as possible?
No. There are two reasons: one is to increase the rated operating voltage by increasing the incoming line voltage; the other is that the harmonics generated by high power will interfere with the power grid, and a relatively straight DC current can be obtained through double rectification, the load current is a rectangular wave, and the load voltage is close to Sine wave, reducing the impact of grid interference on other equipment.
Some enterprises blindly pursue high voltage (some 1000kW use 900V incoming line voltage) and achieve the purpose of energy saving with low current. Don’t you know that this is at the cost of the life of the furnace, and the gain outweighs the gain? High voltage is likely to shorten the life of electrical components. , The fatigue of copper bars and cables greatly reduces the life of the electric furnace.
Disadvantages: high energy consumption, the power consumption per ton of molten steel is more than 700kW•h. The power is adjusted by adjusting the DC voltage, the power factor is low (≤0.85), and there is harmonic interference, which has different degrees of influence on the operation of the reactive power compensation capacitor in the substation.
IGBT
Advantages: The rectification adopts full-wave rectification, and the LC filter method composed of capacitors and inductors is used to make the power factor reach above 0.96, and there is basically no harmonic interference. The inverter part adopts the series inverter working mode, and the load works under the condition of high voltage and low current, and the copper loss is small, which greatly improves the efficiency. Power consumption per ton of molten steel is less than 600kW·h.
Disadvantages: IGBT intermediate frequency power supply has high requirements in the working environment.
KGCL
KGCL thyristor series intermediate frequency power supply inherits the advantages of the above two products, adopts a full-wave rectification power supply, and the rectification is always in the fully open state during the whole working process (equivalent to diode rectification); the power factor of the equipment is always in the highest state (≥0.96). It does not generate high-order harmonics, has no pollution to the power grid, and does not affect the operation of reactive power compensation capacitors in substations. Compared with an ordinary thyristor parallel intermediate frequency power supply, it can save energy by about 15%. Moreover, the accessories are cheap and easy to purchase, and easy to maintain. Therefore, the KGCL thyristor series intermediate frequency power supply is the latest energy-saving intermediate frequency electric furnace product that is mainly promoted.
Aluminum shell or steel shell for induction furnace for steel melting?
The advantages of the aluminum shell furnace body are low price, easy maintenance, and convenient observation. The disadvantage is low efficiency and no electromagnetic radiation shielding.
The steel shell furnace body is welded with a high-quality steel structure and has an anti-leakage furnace alarm device. The sensor is closed with a magnetic yoke, covering more than 65% of the area. Because of the small magnetic flux leakage and high efficiency, it saves energy consumption by nearly 5% compared with the aluminum shell furnace.
Is the longer the melting time, the better?
Absolutely right. The unit power consumption has a lot to do with the smelting method. The working method of the furnace can be divided into the following three situations:
Continuous smelting three shifts of continuous operation per day.
Intermittent smelting two shifts or one shift per day. During the non-working period, the molten iron in the furnace is kept warm with heat preservation power.
Batch smelting all the smelting will be cleaned after the completion of each day.
Obviously, in the above three cases, the energy consumption of continuous smelting is the lowest, followed by the other two. Therefore, concentrated continuous smelting should be arranged as much as possible under conditional conditions. Increase the number of smelting furnaces as much as possible to prolong the continuous smelting time and reduce power consumption.
At last
The basis for the induction furnace for steel melting energy saving is to promote the use of low-loss transformers in the construction of power transmission and distribution projects. The selection of energy-saving intermediate frequency power supplies has a greater impact on the power saving of foundry induction furnaces. There are several ways and methods for the induction furnace to save electric energy in production. For example, prolonging the continuous smelting time, rationally organizing production, scientifically managing the charge, etc.
The energy saving of induction furnaces is a systematic project, and it is also meticulous and arduous work. It is necessary to combine technical energy saving with management energy saving, from equipment, raw materials, process and management, etc. Only by comprehensive and comprehensive control can we save significant energy consumption.
