The so-called hot-air stove is a thermodynamic machine which achieves smelting by raising the temperature through burning. What I want to introduce today is the characteristics of hot-air stove in structure and principle.

　　Structure:

　　hot-air stove consists of grate, refractory brick, reflector, furnace body, flue and air intake pipe, dust collector, chimney and its bracket, induced draft fan (including regulating valve), blower (including regulating valve), special parts, temperature measuring instruments, etc.

　　Principle of hot-air stove:

　　1. Direct high-purification gas hot-air stove

　　burns directly with fuel, forms hot air through high-purity treatment, and directly contacts the material for heating, drying or baking. Based on only half of that using steam or other indirect heaters, the fuel consumption of this method uses direct high-purity hot air without affecting the quality of the dried product, and the fuels are gaseous fuels such as coal gas, natural gas and liquefied gas.

　 The high-temperature combustion gas obtained after the fuel combustion reaction is further contacted with the external air, mixed to a certain temperature, and directly enters the drying chamber or chamber to contact with the materials to be dried, heated and evaporated. For the combustion reaction heat of these fuels, a set of fuel combustion equipment must be added.

　　2. Indirect gas-fired hot-air stove

　　Indirect gas-fired hot-air stove is mainly suitable for drying contaminated materials, or heat-sensitive materials replaced by drying temperature, e.g., milk powder, pharmaceuticals, synthetic resins, fine chemicals, etc. This heating device uses steam, heat transfer oil or flue gas as the carrier, and heats the air through various forms of heat exchangers.

　　 Heat exchange is the most basic problem to indirect gas-fired hot-air stove, because the more subdivided the heat exchange area, the higher the heat conversion rate, the better the energy saving effect and the longer the life of furnace body as well as heat exchanger. Determine the size of heat exchange area. The lower the flue gas temperature, the higher the heat conversion rate and the larger the volume of heat exchange area.