Application of the hottest electrode arc in steelm

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Application of electrode arc in steel-making furnace

an electric furnace that uses the high temperature of electrode arc to make steel. From 1888 to 1892, the industrial direct electric arc furnace was created in ERU, France, which was used in the production of calcium carbide and ferroalloy. From 1900 to 1910, it was used in steelmaking. Now the three-phase electric arc furnace used for steelmaking is manufactured according to the prototype of ERU electric arc furnace, so it is also called ERU electric arc furnace. The furnace body of electric arc steelmaking furnace is composed of furnace cover, furnace door, tapping trough and furnace body. The bottom and wall of the furnace are built with alkaline refractory and medium acid refractory; Electric furnaces built with acid refractories can only use raw materials with very low phosphorus and sulfur, so now it seems that many users of reinforcement factories are using very little. The furnace cover is in a circular arch shape, and is built on a water-cooled steel arch foot ring beam with silicon bricks, magnesium chromium bricks or high aluminum bricks. It can be removed for masonry and removed for loading. Three graphite electrodes arranged in an equilateral triangle pass through the furnace cover and stretch into the furnace, and a furnace transformer supplies power to the electrode through cables, conducting tubes and electrode holders, so that an arc occurs between the end of the electrode and the metal charge, and the electric energy is converted into the heat energy required for heating the furnace and smelting molten steel

the maximum capacity of electric arc furnaces was 100t in the 1930s, 200t in the 1950s and 400t in the early 1970s

high power arc furnace (HP) and ultra-high power arc furnace (UHP) are relative to general ordinary power arc furnace (RP). They are mainly distinguished by the transformer capacity per ton of furnace capacity. Furnaces with a capacity of more than 20t 1. Regularly check whether there is oil leakage at the main engine and oil source. The transformer capacity of ordinary power electric arc furnace is about 300 KVA per ton of furnace capacity, high-power electric arc furnace is about 450 KVA, and ultra-high power electric arc furnace is more than 600 KVA, and there is an increasing trend. This means that the heat energy input into the electric arc furnace in a unit time is greatly increased, so that the melting time is significantly shortened, so as to improve the production capacity, reduce electrode consumption, reduce heat loss, reduce electric energy consumption, and the result is that the production cost is reduced. For example, a 70t ultra-high power electric arc furnace in Nikki, with a transformer capacity of 60000 KVA, is used to refine ball steel. Coupled with refining outside the furnace, the smelting cycle is only 70min, which is equivalent to a high level of steel production of 1 t per minute. In order to make the furnace work under the best electrical system (the fullest and most economical use of electrical energy), many ultra-high power electric arc furnaces use electronic meters to control computers when the stress reaches the highest point. The power of ultra-high power electric arc furnace is large, and the heat input into the furnace per unit time is also large, so the refractory material has become a weak link. In recent years, steel water-cooled furnace walls and covers coated with refractory materials have been studied and used

ultra high power electric arc furnace has outstanding advantages, but it must have the following conditions to give full play: ① strong power supply. The short-circuit capacity shall be more than 80 times of the maximum furnace transformer capacity. Or install a huge capacitance compensation device (which is expensive) to reduce the voltage fluctuation on the path, so as not to affect the normal work of other electrical equipment. ② Ultra high power electrode. The electric energy input of ultra-high power arc furnace in unit time is much higher than that of ordinary power arc furnace, which is not competent for ordinary power electrodes with the same section. Increasing the electrode section will make its support, transmission and even the structure of the whole furnace cumbersome, and it will also cause difficulties to the control system. The raw material of ultra-high power electrode is acicular asphalt, and the crystalline structure of the electrode has directionality. Its conductivity, thermal conductivity, oxidation resistance, strength and other properties are better than ordinary power electrodes with cross-sections such as superconducting materials, carbon fibers, graphene, 3D printing and other cutting-edge materials, which not only leap into people's vision. ③ Efficient production management system. According to the investigation results of 19 ultra-high power electric furnaces, about 20% achieved the effect of ultra-high power, 60% only played 60 ~ 70% of the capacity, and the other 20% did not play a role. Among them, the production organization and management is extremely important. It cannot be simply considered that the expected purpose can be achieved by equipping a large capacity transformer for the electric arc furnace. Due to the emergence of ultra-high power electric arc furnace and various refining methods outside the furnace, electric arc furnace has the trend of being a simple melting equipment in recent years; Besides, the refining equipment outside the furnace corresponding to the steel grade produced shall be configured to make full use of the capacity of the furnace transformer and improve the steelmaking output

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