Continuous automatic firing electrode, referred to as self firing electrode, is composed of electrode paste and iron shell. The electrode is constantly consumed when working in the calcium carbide furnace, so it is necessary to continue to discharge the electrode to supplement it. When the electrode is placed under the conductive jaw, the electrode paste is carbonized to form an electrode through high-temperature baking at about 1000°C. Because the electrode iron shell can continue to be welded without power failure in the electric furnace, the electrode paste is continuously added to the iron shell, and it is sintered in the calcium carbide furnace, so it is called continuous automatic baking electrode.
Self-fired electrodes are widely used in calcium carbide furnaces and ferroalloy furnaces. The characteristic of this kind of electrode is that the diameter can be expanded to 2 meters, it is very convenient to connect on the calcium carbide furnace without screw joint, and the price is low. This creates favorable conditions for the development of calcium carbide furnace to large capacity. In the entire equipment of the calcium carbide furnace, the electrode is the heart. In the production of calcium carbide, the electric current is inputted into the furnace through the electrodes to generate an electric arc to smelt calcium carbide. The electrode occupies an extremely important position in the entire electric furnace. There are many parameters in the design of calcium carbide furnace with reference to the diameter of the electrode.
The size of the electrode diameter is determined by the current density allowed by the current passing through the electrode cross-sectional area. If the diameter is small, the allowable current density is large; if the diameter is large, the allowable current density is small. The selection of current density and electrode diameter is very important for the entire electric furnace.
The determination of the electrode diameter has great guiding significance for the design of considering the electrode concentric circle diameter, electrode spacing, furnace inner diameter, furnace depth, even the outer diameter of the furnace, and the thickness of the bottom of the furnace. Because the data of these dimensions refer to the empirical data of multiple relationship with the electrode. Three-phase electric furnace electrodes generally adopt a triangular arrangement. When designing, it is necessary to consider the distance between the electrodes, so that it has sufficient and uniform temperature distribution, and can form a larger high-temperature area that can collude with each other, and also consider that there is enough distance between the electrode and the furnace wall to make it be against the furnace.
The wall radiation is uniform to avoid the furnace wall from burning out too quickly. The ratio of the diameter of the electrode concentric circle to the inner diameter of the furnace wall is generally 0.44. The inner diameter of the furnace is 2.25 times the diameter of the electrode concentric circle. Regarding the ratio of the electrode concentric circle diameter to the electrode diameter, most of the empirical data used are currently 2.7 times better. The depth of the furnace is 2.3 times the diameter of the electrode.
In addition, the diameter of the electric furnace, the depth of the electrode inserted into the charge, the thickness of the bottom of the furnace, the area of the bottom of the furnace, and the furnace capacity are all related to the electrode. It can be seen that the electrode occupies an extremely important position in the design of the entire electric furnace equipment. At present, most of the electrodes in domestic electric furnaces use self-burning electrodes, and the accidents we often encounter in the entire electric furnace equipment are electrode accidents. These accidents are soft broken electrodes, hard broken electrode shell ruptures, electrode leakage, electrode “stabbing fire”, electrodes cannot be put down and so on.
Where an accident occurs in the electrode, it affects the normal production of the electric furnace, and sometimes causes the production to stop for dozens of hours or days, a lot of manpower and material resources are wasted, and even serious personal injuries occur. In short, the electrode occupies an important position in the calcium carbide furnace. Without it, the electric furnace cannot function. If it has a problem, the entire furnace production will not be able to proceed normally, or even paralyzed. Therefore, as a calcium carbide production worker, it is necessary to understand the composition, performance, production method, function and influence of the electrode paste on the electric furnace.