Radiant Tube Burner Editing
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Radiant tubes are heated by fuel combustion sprayed from burners inside the tube. To meet process requirements, the radiant tube burner must ensure uniform temperature distribution on the inner wall surface without local overheating. It should have good flame stability and be able to burn stably even under low air consumption coefficients. Frequent on-off operations should not cause flashback or severe carbon deposition. During the entire combustion adjustment process, the air consumption coefficient should remain relatively stable. The preheater can preheat combustion air to above 400°C. NOx emission concentration is below 80×10-6, and noise is below 70dB(A). The surface temperature of the burner and fixing devices is less than 100°C, facilitating maintenance and ensuring reasonable service life. Radiant tube burners can be classified into forced draft, induced draft, suction, and suction-forced types based on air supply methods. Forced draft: Air is blown in as combustion air, with natural exhaust. Due to positive pressure inside the tube for safety reasons, this type is rarely used now. Induced draft: Combustion air is drawn from the workshop by negative pressure created by ejector air, with natural exhaust; the tube is under negative pressure, and this is the most commonly used type. Suction type: Combustion air is drawn from the workshop by negative pressure created by ejector air, and exhaust gas is forced out by an exhaust fan. The more advanced type is suction-forced, where air is blown in as combustion air and exhaust gas is forced out by an exhaust fan. Compared to traditional induced draft type, it has many advantages, the most prominent being easy control of the air consumption coefficient. Under normal conditions, the fluctuation range of the air consumption coefficient for induced draft radiant tube burners is 1.15 to 1.50, while for suction-forced type it is 1.05 to 1.15. In recent years, regenerative (HTAC) combustion technology has emerged. To improve the combustion thermal efficiency of radiant tubes, regenerative burners have also been adopted for radiant tubes. This technology uses a pair of regenerative burners. HTAC combustion technology has achieved great success in conventional heating furnaces and has begun to be applied in protective atmosphere furnaces with radiant tube heating. However, due to many practical problems yet to be solved in application, its promotion is not fast. But as problems are solved and equipment improves, this technology will see rapid development in the field of radiant tube heating technology.
The electric heating alloy material used for radiant heating tubes should have high resistivity and high electrothermal conversion efficiency. Since the radiant tube is placed inside a sleeve, the heat transfer process differs from that of general exposed electric heating elements. It has high thermal shielding, and the element temperature must be controlled during heating to prevent overheating. When the radiant tube is heated in a closed manner, the surface temperature of the electric heating element is about 100°C-150°C higher than the furnace temperature. Therefore, when selecting materials, it is necessary to analyze the furnace temperature and atmosphere inside the furnace to choose the correct heating material.
Currently, the radiant tube heating tube series include squirrel cage type, vertical strip type, and spiral type. The heating elements are made of imported or domestic resistance wire, nickel-chromium wire (or strip), iron-chromium-aluminum (wire or strip). The protective tube is made of imported high-temperature alloy plate, heat-resistant steel plate rolled and welded, or centrifugally cast, featuring high-temperature oxidation resistance, good carburization resistance, and long service life [1]
Main Technical and Performance:
1. Cold resistance error range of electric heating wire ≤3%
2. Insulation resistance between outer protective tube and heating wire is greater than 2MΩ
3. Outer diameter of heating tube: various specifications from φ60mm to φ300mm
4. Heating power: various specifications from 2KW/piece to 24KW/piece
5. Length of heating tube outer tube: various specifications from 800mm to 2800mm
6. Wall thickness of radiant tube outer tube: various specifications from 1.5mm to 16mm.
Note: The above information and technical parameters are compiled and released by Yangzhou Dari Electric Co., Ltd.
