Common types and components of electric arc furnaces

An electric arc furnace is an electric furnace that smelts ores and metals using the high temperature generated by an electrode arc. When the gas discharge forms an arc, the energy is very concentrated, and the temperature of the arc zone is above 3000 °C. For metal smelting, the electric arc furnace is more flexible than other steelmaking furnaces, and can effectively remove impurities such as sulfur and phosphorus. The furnace temperature is easy to control, and the equipment occupies a small area.

Common types of electric arc furnaces

There are many ways to classify electric arc furnaces

According to the smelting form of the electrode, it is divided into

(1) Non-consumable electrode type electric arc furnace, which uses tungsten or graphite as electrodes, and the electrodes themselves do not consume or consume very little during the smelting process.

(2) Consumable electrode arc furnace, which uses the smelted metal as the electrode, and the metal electrode is melted and consumed by itself.

According to the control method of arc length, it is divided into

(1) Constant arc voltage automatic control type electric arc furnace, which relies on the comparison between the voltage between the two electrodes and the given voltage, and the difference is driven by signal amplification to drive the consumable electrode to rise and fall to keep the arc length constant.

(2) Constant arc length automatic control type electric arc furnace, which relies on the constant arc voltage to approximately control the constant arc length.

(3) Droplet pulse automatic control type electric arc furnace, which automatically controls the constant arc length according to the pulse frequency and the relationship between the pulse duration and the arc length generated during the formation and dripping of metal droplets.

Divided according to the form of work

(1) Periodic operation type electric arc furnace, that is, each smelting furnace is regarded as a cycle.

(2) Continuous operation type electric arc furnace, this type of electric arc furnace has two forms. One is the furnace body rotating type; the other is that two furnaces share a DC power supply, that is, when the melting of one furnace is completed, the power supply is switched to the other furnace to immediately start the melting of the next furnace.

According to the structure of the furnace body, it is divided into

(1) Stationary electric arc furnace.

(2) Rotary electric arc furnace.

What are the components of an electric arc furnace

The furnace body is generally divided into two parts: the upper furnace body and the lower furnace body.

The whole electric furnace can be divided into furnace body and furnace cover. Tilt system. Electrode lift system. Short grid (power supply) system. Hydraulic system. feeding system. Cooling water system. Oxygen blowing part. Lime injection part.

Main features of arc furnace

Electric arc steelmaking furnaces use electric energy as the main energy source. The electric energy draws the arc through the graphite electrode and the charge discharge, generating a high temperature of 2000 ~ 6000 ℃ or more, and melting the scrap steel raw material by means of arc radiation, temperature convection and heat conduction. During most of the time when the charge is melting, the high-temperature heat source is surrounded by the charge, and the heat loss caused by the high-temperature exhaust gas is relatively small, so the thermal efficiency is higher than other steelmaking equipment such as converters. In addition, electric heating can easily and accurately control the furnace temperature, and the heating operation can be carried out under any conditions such as oxidizing atmosphere or reducing atmosphere, normal pressure or vacuum according to process requirements.

The electric arc furnace steelmaking process is short, the equipment is simple, the operation is convenient, it is relatively easy to control pollution, the construction investment is small, the floor area is small, and it does not need to rely on the complicated ironmaking system like the converter steelmaking.

Electric arc furnace steelmaking has strong adaptability to the charge. It uses scrap steel as the main raw material, but at the same time it can also use molten iron (blast furnace or iron furnace molten iron), sponge iron (DRI) or hot briquetting (HBI), pig iron and other solid state and liquid iron containing raw materials.

Due to the controllable atmosphere in the EAF steelmaking furnace, the operation of slag adjustment or replacement is relatively easy, and the melting, decarburization, dephosphorization, degassing, removal of inclusions, temperature control, composition can be completed in the same operating system Complex process operations at various stages such as adjustment (alloying). Electric arc furnace steelmaking can be intermittently produced, and the production varieties can be flexibly exchanged within a certain range. In addition, modern electric arc furnaces can also use a large amount of auxiliary energy, such as injection of heavy (light) oil, pulverized coal, natural gas, etc. Therefore, the electric arc furnace steelmaking process has strong adaptability, flexible operation and wide application.

The electric arc furnace can not only smelt high-quality steel with low phosphorus, sulfur and oxygen content, but also alloy with a variety of elements (including easily oxidized elements such as lead, boron, vanadium, titanium and rare earth) to produce various high-quality steel. Steel and alloy steel, such as ball bearing steel, stainless acid-resistant steel, tool steel, electrical steel, heat-resistant steel, magnetic materials and special alloys.

Although electric arc furnace steelmaking has many advantages, due to the current cost of scrap steel and electricity prices in my country, electric arc furnace steelmaking cannot compete with converter steelmaking in ordinary steel and long-term products. Electric arc furnace steelmaking only occupies a dominant position in the field of special steel production with small batches, multiple varieties and high alloy ratios.