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As one of the professional submerged arc furnaces manufacturers, Hani Metallurgy is willing to introduce the differences between DC-submerged arc furnaces and AC-submerged arc furnaces. The submerged arc furnaces on the market are generally divided into two types: DC submerged arc furnaces and AC submerged arc furnaces in terms of the current form. Each type of submerged arc furnace is divided into open arc furnace (submerged arc furnace is exposed outside the raw material, also called submerged arc furnace) and submerged arc furnace (submerged arc furnace is buried inside the raw material, also called submerged arc furnace).
Let’s talk about the AC submerged arc furnace first. The structure of the AC furnace is relatively simple, the three-phase AC is connected to the three electrodes, and there is no complicated rectifier circuit, so the cost is relatively low. Price is the advantage of AC furnaces. However, due to the characteristics of the alternating current itself, the mine heat light of the alternating current furnace is constantly repeating the process of arc starting and arc extinguishing, that is to say, the arc light is unstable. Moreover, the power factor of the AC furnace is relatively low, with an average of 0.85, which means that 15% of the electric energy is wasted, and the reactive power compensation device must be added to 0.9.
At the same time, each set of AC furnaces is calculated and designed in strict accordance with the conditions of the materials, and you cannot arbitrarily change the properties of the raw materials. For example, at the time of design, the grade of iron in your raw material is 55. Now that the furnace is produced by submerged arc furnace manufacturers, you get better materials. When the grade of iron rises to 80, your stove can no longer be used, and the grade must be lowered to 55 or so. The arc length of the AC furnace cannot be arbitrarily changed. For the AC furnace, the open arc and the submerged arc cannot be arbitrarily changed, and only one can be selected.
Then talk about the DC furnace. The DC furnace needs to pass the rectifier circuit to convert the alternating current into direct current. In the case of direct current, the mine heat will not be repeated on and off, and it can be maintained in a stable state. The power factor of the DC furnace can generally reach more than 0.9. According to the number of electrodes, DC furnaces are divided into single-electrode furnaces and double-electrode furnaces. There is only one graphite electrode above the single-electrode furnace, which is the negative electrode, and the positive electrode is at the bottom of the furnace, which is called the bottom electrode. Both the positive and negative graphite electrodes of the dual-electrode furnace are above the furnace. Most submerged arc furnace manufacturers on the market produce single-electrode furnaces.
However, a serious problem with single-electrode furnaces is that the bottom electrodes are easily damaged. Since the furnace bottom electrode must be in contact with the furnace bottom graphite bricks, and the furnace bottom graphite bricks must be in contact with the raw materials in the furnace, during the smelting process, the temperature in the furnace is very high. In the case of continuous production, the temperature of the graphite bricks may be above 1000°C, the bottom electrode will be melted at a high temperature.
When the bottom electrode is melted, it cannot be used. At this time, it is necessary to replace the bottom electrode and rebuild the lining refractory. If it is a small test furnace, it will not matter if it is replaced once. If it is a large industrial furnace, it will take at least 15 days to replace the furnace bottom, which will cause great losses.
In order to solve this problem, we devote ourselves to developing double-electrode equipment. The problem of electrode melting at the furnace bottom is completely solved. However, due to the different temperatures at the lower part of the positive and negative electrodes, one side of the raw material has melted and the other side has not. For this reason, we have developed a positive and negative electrode conversion system, which converts the electrode polarity every other period of time to make the melting temperature uniform.
The power factor of our equipment is at least 0.95, which sounds a little higher than 0.9, but the technical content is different. Just like the thermal efficiency of automobile engines, when the thermal efficiency of other brands of engines is only 0.35~0.37, Toyota engines can reach 0.4, which requires a lot of time and money to research. This is the technology gap.
The big advantage of our equipment from our submerged arc furnaces manufacturers is its high-free operation. Our equipment can change the arc length at will, which can realize both open arc and submerged arc. The current can be adjusted arbitrarily without changing the arc length. Therefore, our equipment can smelt any material you can find. You can smelt any ore, metal, solid waste, and hazardous waste. For example, if you think you can make money by smelting ferroalloy, you can smelt ferroalloy. If the market changes in the future and you can make money by smelting precious metal ores, you can smelt precious metal immediately without changing equipment.
If you are looking for professional submerged arc furnaces manufacturers, please don’t hesitate to contact us, we can supply different and customized submerged arc furnaces according to your tech requirement. We are also specialized in upgrading your existing furnaces to increase production and improve efficiency.