Industrial furnace is in the industrial production, the use of fuel combustion or electrical energy into heat, heat the material or artifacts of thermal equipment. Broadly, the boiler is a kind of industrial furnaces, but people are not used to include it within the scope of the industrial furnace.

Industrial furnaces of the main components are: industrial furnace, industrial furnace masonry, industrial smoke fire grate system preheater and industrial furnace combustion equipment, etc. Mechanical industry application there are many types of industrial furnace, in the foundry workshop, melting metal cupola and induction furnace, resistance furnace, electric arc furnace, vacuum furnace, furnace and crucible furnace, etc.; Have roasted sand mold sand mold oven drying furnace, ferroalloy, casting annealing furnace, etc.; In the forging workshop, have on prior to forging ingot and billet heating furnace, and eliminating stress after forging heat treatment furnace; In the metal heat treatment workshop, improve mechanical properties of the workpiece, annealing, normalizing, quenching and tempering heat treatment furnace; In the welding workshop, welding preheating furnace before welding and after welding tempering furnace; In the powder metallurgy workshop has a sintered metal heating furnace, etc.

Industrial furnace is widely used in other industries, such as metallurgical industry of metal melting furnace, ore sintering furnace and coke oven; Oil industry distillation furnace and cracking furnace; Industrial gas occurrence boiler; Silicate industry of cement kiln and glass melting, glass annealing furnace; The food industry of baking furnace, etc.

The creation of industrial furnace and development plays an important role in human progress. China appeared in the shang dynasty is relatively perfect copper smelting furnace, furnace temperature reached 1200 ℃, the stove inside diameter of 0.8 meters. In the spring and autumn period and the warring states period, people in molten copper furnace on the basis of further mastered the technology to improve furnace temperature, so as to produce the cast iron.

In 1794, the world appeared a straight cylindrical cupola melting cast iron. By 1864, after the French Martin apply principles of British Siemens regenerative furnace, built in the first steelmaking furnace fuel gas heating. He used the regenerator to high temperature of air and gas, so as to ensure the steel needed for the temperature above 1600 ℃. Around 1900, power supply is adequate, gradually began to use a variety of resistance furnace, electric arc furnace and cored induction furnace.

In the 20th century 50 s, coreless induction furnace to get rapid development. Then the electron beam furnace, the use of electron beam to hit solid fuel, can strengthen the surface heating and melting of the high melting point materials.

Used to forge heating furnace was first hand forging furnace, its workspace is a concave groove, groove, fill in the coal combustion with air from the bottom of the tank into the, artifacts buried heating in the coal. This stove thermal efficiency is very low, the heating quality is not good, and can only heat the small artifacts, after development for refractory brick build by laying bricks or stones becomes close partly or fully enclosed chamber of a stove or furnace chamber furnace, can use coal, gas or oil as a fuel, also can use electricity as a heat source, the workpiece in the furnace heating.

For convenience of heating of large workpiece, appeared the car type is suitable for big ingot and billet heating furnace, heating to long bar also appeared well type furnace. After the 1920 s appeared to increase the furnace productivity and improve the working conditions of mechanization, automation of furnace type.

Industrial furnace fuel is also due to the development of fuel resources and fuel conversion technology progress, and by using coal, coke, coal and other solid fuels gradually switch to producer gas, city gas, natural gas, gas and liquid fuels such as diesel oil, fuel oil, and developed and that meet the needs of all kinds of fuel used in combustion device.

The structure of industrial furnace, heating process, the temperature control and furnace atmosphere etc., will directly affect the quality of the products after processing. In forging furnace, improve the heating temperature of the metal, can reduce the resistance to deformation, but the temperature is too high will cause the grain growth, oxidation or burnt, serious impact on quality of workpieces. In the process of heat treatment, if the steel is heated to above the critical temperature point, and then suddenly cooling, can improve the hardness and strength of steel; If heated to a temperature below the critical temperature of slow cooling after a certain point, and can reduce the steel hardness and toughness.

In order to obtain size precise and smooth surface of the workpiece, or to reduce the metal oxide to achieve protection mould, reduce machining allowance, etc., can be used in a variety of less oxidation furnace. Within the open flame less, no oxidation furnace, reducing gas generated by the incomplete combustion of fuel in heating the workpiece can make oxidation burning loss rate is reduced to below 0.3%.

Atmosphere is the use of artificial preparation of controlled atmosphere furnace, the flux charging can be carried out in gas carburizing, carbonitriding, the bright quenching, normalizing, annealing and other heat treatment: change the microstructure and improve the mechanical properties in order to achieve the purpose of. In liquid particle in the furnace, using the fuel combustion gas, other fluidizing agent or external, forced through the furnace bed layer of graphite particles or other inert particles, buried artifacts in particle layer can achieve improved heating, can also be used for carburizing, nitriding and other non oxidation heating. In the salt bath furnace, molten salt solution was used as heating medium, can prevent the workpiece oxidation and decarburization.

In cupola melting cast iron, tend to get a coke quality, air distribution mode, furnace charge and air temperature conditions, the influence of the smelting process is difficult to stability, not easy to get high quality hot metal. Hot air cupola can effectively increase the hot metal temperature, reduce metal loss, decrease the rate of molten iron oxide, which can produce cast iron.

With the emergence of coreless induction furnace, cupola is gradually being replaced. This induction furnace smelting work is not restricted by any cast iron grades, can from a grades of cast iron smelting, quickly switch to another level of smelting iron, is conducive to improve the quality of molten iron. Some special alloy steel, such as ultra-low carbon stainless steel roll and the use of steam turbine rotor steel, you need to open hearth or general electric arc furnace smelting of steel, in refining furnace by vacuum degassing and argon stirring to miscellaneous, further refining high purity, large capacity, high quality steel.

Industrial furnace according to the heating method is divided into two kinds: one kind is flame furnace (or fuel furnace), with solid, liquid or gas fuel combustion in furnace heat for heating workpiece; The second is electric furnace, converts electrical energy into heat in the oven for heating.

Flame furnace fuel source wide, low price, easy to adjust measures to local conditions to take a different structure, to reduce the production cost, but the flame furnace is difficult to achieve precise control, serious pollution to the environment, the thermal efficiency is low. Electric furnace is characteristic of furnace temperature uniformity and easy to realize automatic control, heating quality. According to the way of energy conversion, electric furnace and can be divided into electric resistance furnace, induction furnace, electric arc furnace.

Industrial furnace according to the thermal system and can be divided into two categories: one is discontinuous furnace is also called the cycle type furnace, the furnace is characterized by intermittent production, furnace temperature is variable in each heating cycle, such as chamber furnace, trolley furnace, pit type furnace, etc.; The second type is continuous furnace, its characteristic is the furnace continuous production, the division in the hearth temperature sections. In each section of the temperature in the heating process is the same, the workpiece by the low temperature of preheating zone gradually into the high temperature heating zone, such as continuous furnace and heat treatment furnace, furnace, furnace step by step, vibration of bottom furnace, etc.

Per time unit heating ability of furnace calculated by unit bottom area known as the furnace productivity. Furnace temperature the faster, the fire load, the greater the furnace productivity is higher. In general, the furnace productivity is higher, the heating unit heat consumption per kilogram of materials is lower. Therefore, in order to reduce energy consumption, should be at full capacity production, try to increase the furnace productivity, fuel and combustion air for combustion devices at the same time automatic proportional control, in order to prevent the excessive or insufficient air quantity. Also, reduce the accumulating heat furnace wall heat loss, water-cooled heat loss components, all kinds of openings of radiant heat loss, away from the furnace flue gas heat loss, etc.

Metal or materials to absorb heat and for charging when the heating in the ratio of the heat, is called the furnace thermal efficiency. Continuous furnace than intermittent furnace thermal efficiency is high, because of the high continuous furnace productivity, and is a continuous work, the furnace heat system is stable, no periodicity of the furnace wall heat loss, also due to internal have a preheating furnace burden extents, flue gas waste heat is in part due to internal have a preheating furnace burden section, part of flue gas waste heat absorbed by cold artifacts for charging, reduced from the furnace flue gas temperature.

In order to make the furnace temperature is constant and the implementation rules of heating speed, except must according to the technological requirements, preheater and furnace used mechanical type, fuel and combustion device categories, industrial smoke fire grate way to determine the good furnace type structure, the need for fuel and combustion air flow and pressure, or electric power, and other controllable variables through a variety of control units for mutual adjustment, in order to realize the furnace temperature and furnace atmosphere or automatic control of furnace pressure.