Melting furnace working principle and heating method
The application range of melting furnace is very wide, but it is very common in some metal processing fields. Then, what is the working principle of melting furnace and what principle is used to heat it. Next, I will explain in detail about melting About the furnace. What is the principle of the smelting furnace: Smelting is to put metal materials and other auxiliary materials into the heating furnace to melt and temper, and the materials in the furnace at high temperature (1300 ~ 1600K) undergo certain physical and chemical changes to produce crude metal or metal-rich materials. Pyrometallurgical processes of aggregates and slags. In addition to concentrate, calcine, sinter, etc., the charge of the charge sometimes needs to be added with a flux to make the charge easy to melt, and a reducing agent for a certain reaction. In addition, in order to provide the necessary temperature, it is often necessary to add fuel to burn, and send air or oxygen-enriched air. The crude metal or metal enrichment is separated due to the low mutual solubility with the molten slag and the difference in density into two layers. The concentrates include matte, yellow slag, etc., which must be processed by blowing or other methods to obtain metal. Melting furnace 1. According to the heating energy classification, Kehua smelting furnace can be divided into the following two types: (1) Fuel heating type (including natural gas, liquefied petroleum gas, coal gas, diesel oil, heavy oil, coke, etc.), burning with fuel The reaction heat generated during the heating heats the charge. (2) Electric heating type, the resistance element is energized to generate heat or the coil is energized to generate an alternating magnetic field, and the charge in the magnetic field is heated by an induced current. 2. Classification by heating method (1) Direct heating method The heating method in which the heat generated when the fuel is burned or the heat generated by the resistance element is directly transferred to the charge is called the direct heating method. Its advantages are high thermal efficiency and simple furnace structure. The disadvantage is that the harmful impurities contained in the combustion products will adversely affect the quality of the charge; the harmful gases volatilized from the charge or covering agent will corrode the resistance components and reduce their service life; during the fuel combustion process, the excess air content in the combustion products is high, Causes a large amount of metal burning loss during the heating process. (2) Indirect heating method There are two types of indirect heating methods. The first type is that the combustion product or the energized resistance element does not directly heat the charge, but first heats the heat transfer medium such as the radiant tube, and then the heat is transferred to the charge by radiation and convection; the second type is to pass the coil through alternating current. The alternating magnetic field heats the charge in the magnetic field with an induced current, and the heating elements such as the induction coil and the charge are separated by the lining material. The advantage of the Kehua indirect heating method is that the combustion products or electric heating elements and the charge are separated, and there is no harmful effect on each other, which is beneficial to maintain and improve the quality of the charge and reduce the metal burning loss. The induction heating method also has a stirring effect on the metal melt, which can accelerate the metal melting process, shorten the melting time and reduce the metal burning loss. The disadvantage is that the heat cannot be directly transferred to the charge. Compared with the direct heating method, the thermal efficiency is low and the furnace structure is complex. Smelting furnace 3. Classification according to the operation mode (1) Continuous furnace The charge of the continuous furnace is loaded from the charging side. After the heating and heat preservation processes are completed according to the given temperature curve in the furnace, the furnace is continuously or continuously at a certain speed. Comes out from the discharge side at a certain time interval. Continuous furnaces are suitable for producing products with few varieties and large batches. (2) Periodic furnace The charge of the periodic furnace is added to the furnace in batches according to a certain period, and all the processes such as heating and heat preservation are completed according to a given temperature curve, and then all are transported out of the furnace. Periodic furnaces are suitable for producing products with many varieties and specifications. 4. Classification according to the atmosphere in the furnace (1) Non-protective gas type The atmosphere in the furnace is air or the combustion atmosphere of the fuel itself, which is mostly used for products that can form a dense protective layer on the surface of the charge at high temperature and can prevent violent oxidation at high temperature. (2) Protective gas type If the oxidation degree of the charge is not easy to control, the furnace is usually evacuated to a low vacuum, and nitrogen, hydrogen and other protective gases are introduced into the furnace to prevent the charge from being oxidized violently at high temperatures. With the continuous improvement of the internal and external quality requirements of products, the scope of use of protective gas furnaces has been continuously expanded. Melting furnaces can dissolve and cast some metal workpieces, so many parts manufacturers will buy these equipment. In fact, there are many types of melting furnaces that have been used.