1794, the world has witnessed a straight-shaped cast iron melting cupola. After 1864, Frenchman Martin use the British Siemens regenerative furnace principle, the construction of gas fuel heating the first open-hearth steelmaking. He used the regenerators for air and gas preheat temperature, thus ensuring the required steel temperature above 1600 ℃. 1900, power supply gradually enough to start using a variety of resistance furnace, electric arc furnace and a coreless induction furnaces.
1950s, coreless induction furnaces have developed rapidly. Later appeared electron beam furnace, using electron beam to the impact of solid fuel, can strengthen the surface heating and melting melting point of the material. First heating furnace for forging the hand forging furnace, its working space is a concave groove, the tank fill the coal, the combustion air fed into the lower portion of the slot, the workpiece is heated in buried in the coal. The thermal efficiency of the furnace is very low, the heating quality is not good, and only heating small parts, after the development of a refractory brick semi-closed or closed hearth furnace chamber can be coal, gas or oil as fuel , but also electricity as the heat source, the workpiece is placed inside the heating furnace.
For heating large workpieces, there was great for heating ingots and billets bogie hearth furnace, for heating elongated rod member also appeared pit furnace. 1920s and later appeared to improve furnace productivity and improve working conditions for all kinds of mechanization and automation furnace. Industrial furnace fuel resource development along with the fuel and fuel switching technology, but by the use of lump coal, coke, coal and other solid fuels gradually switch furnace gas, city gas, natural gas, diesel, fuel oil and other gases and liquid fuel, and the production of the fuel used and adapted to various combustion devices.
Box-type structure of high-temperature furnace, the heating process, temperature control, and the furnace atmosphere, you will have a direct impact on the quality of the products after processing. In forging furnace, the heating temperature increase the metal, the deformation resistance can be reduced, but the temperature is too high will cause grain growth, oxidation or burnt, seriously affecting the quality of the workpiece. During the heat treatment, if the steel is heated to a point above the critical temperature, and then suddenly cooled, can improve the hardness and strength of steel; if heated to a point below the critical temperature and then slowly cooled, the hardness of the steel and can leaving lower toughness.
In order to obtain accurate dimensions and surface finish of the workpiece, or in order to reduce the metal oxide in order to protect the mold, reducing the allowance purposes, you can use a variety of less or non-oxidizing furnace. No open flame in less oxidation furnace, the incomplete combustion of the fuel reducing gas generated in which the workpiece is heated oxidation loss rate can be reduced to 0.3%.
Controlled atmosphere furnace using the artificial preparation of the atmosphere gas can be introduced into the furnace carburizing, carbonitriding, quenching, normalizing, annealing treatment: in order to change the microstructure, the purpose to improve the mechanical properties of the workpiece. Particles in the flow furnace, the fuel combustion gas, or externally applied to other fluidizing agents, forced flow of the furnace bed of graphite particles or other inert particle layer, the workpiece is embedded in the particle layer to achieve enhanced heat infiltration can also be carbon, nitrogen, and other non-oxidizing heating. In a salt bath furnace, a molten salt solution as a heating medium, to prevent oxidation of the workpiece and decarburization.
In cupola furnace smelting iron, are often subject to coke quality, air supply, charge air temperature and other circumstances and conditions, the melting process is difficult to stable, easy access to quality hot metal. Hot air cupola can effectively improve the hot metal temperature, reducing alloy burning, reduce the rate of molten iron oxide, which can produce high quality cast iron.
With the emergence of coreless induction furnaces, cupola has gradually been replaced by the trend. This induction furnace melting iron level work without any restrictions, to a hierarchy from the smelting of iron, quickly switch to another level of iron smelting, help to improve the quality of molten iron. Some special alloy steel, such as low carbon stainless steel and roll and the turbine rotor of the steel used, or a general need to be open hearth arc melting out of the molten steel in the vacuum refining furnace and argon in addition to miscellaneous stirred further refine the High purity, high-quality steel capacity.
Flame furnace fuel source wide, low price, ease of local conditions to take a different structure, help to reduce production costs, but the flame furnace difficult to achieve precise control of environmental pollution, low thermal efficiency. Furnace temperature uniformity and ease of features to achieve automatic control, heating and good quality. By way of energy conversion, electric furnace can be divided into resistance furnace, induction furnace and electric arc furnace. In unit time and unit area of ??the hearth furnace heating ability is called furnace productivity. Faster heating furnace, the furnace loading increases, the productivity of the furnace is higher. In general, the higher the productivity of the furnace, the heating unit of heat per kg of material consumption is also lower. Therefore, in order to reduce energy consumption, it should be at full capacity to maximize the productivity of the furnace, while the combustion of fuel and combustion air system to implement the automatic ratio adjustment, the amount of air in order to prevent excessive or inadequate. Also, to reduce heat loss and storage furnace wall, water-cooled heat loss components, all openings radiative heat loss, the heat removed from the flue gas losses.
Heating the metal or materials absorb the heat and the heat supplied to the furnace, is known as furnace thermal efficiency. Than intermittent continuous furnace furnace thermal efficiency, since the production of a continuous furnace is high, and is uninterrupted, the furnace heat system in a stable state, there is no periodic regenerative furnace wall loss, but also because the furnace has an internal pre- hot charge section, some heat to the furnace gas inside a furnace charge preheating section into the furnace flue gas residual heat is absorbed by a cold work, reducing the temperature of the flue gas from the furnace.
In order to achieve the required oven temperature and a constant heating rate, in addition to according to process requirements, preheater and furnace mechanical type, the fuel and combustion device classes, box-type furnaces exhaust methods to determine the furnace structure fine, but also the need for fuel and combustion air flow and pressure, or other control variables on the electrical power control unit through a variety of mutual adjustment, to achieve the furnace, the furnace atmosphere or in the automatic control of the furnace pressure. Gas is liquefied petroleum gas, natural gas, coke oven gas, city gas, converter gas, mixed gas, producer gas, blast furnace gas, etc..
没有评论:
发表评论