The thermal insulation measures of U-shaped conveyors need to be targeted at the transportation scenarios of high-temperature materials (such as smelting slag, hot aggregates, dried grain, etc.). A multi-layer protection system should be constructed from three aspects: trough structure, material selection, and auxiliary devices. The following is a specific solution:
1. Thermal insulation design of tank structure
Double jacket structure
The inner layer is made of high temperature resistant stainless steel (such as 310S, temperature resistant to 1200℃) or heat resistant cast iron (such as RTCr2, temperature resistant to 600℃), with a thickness of 8-12mm, and is in direct contact with high temperature materials;
The outer layer is ordinary carbon steel ( Q235B ), with a thickness of 5-6mm and a distance of 50-100mm between the two layers , forming an air insulation layer (the thermal conductivity of air is 0.023W/(m・K) , which is more than 200 times lower than that of metal ).
Optimization point: The jacket room can be filled with static air (needs to be sealed) or flowing air (connected to a low-temperature air source). The latter recovers the exhaust gas heat through a heat exchanger, increasing the overall insulation efficiency by 30%.
Arc trough diversion design
Adjust the curvature of the U -shaped trough bottom from the traditional R500mm to R800mm , increase the material stacking thickness (recommended ≥ 300mm ), and use the material itself as a heat insulation layer (such as the thermal resistance of the hot aggregate stacking is 1.5 (m・K)/W );
The inclination angle of the tank is controlled at 15°-20° to extend the residence time of the material and keep the surface temperature ≤60℃ (safe value for human contact).
2. Selection and application of thermal insulation materials
Primary insulation material
High temperature scenario (＞600℃):
The inner layer is coated with nano-ceramic thermal insulation coating (such as ZS-1 thermal insulation coating, thermal conductivity 0.03W/(m・K) , temperature resistance 1800 ℃), the coating thickness is 0.5-1mm , which can reduce the outer surface temperature by 100-300 ℃;
The interlayer is filled with ceramic fiber blanket (such as Morgan Superwool, density 128kg/m³, temperature resistance 1260℃), thickness 50-100mm, heat loss <50W/m².
Medium and low temperature scenarios (200-600℃):
Aerogel insulation felt (such as Aspen Aerogels , thermal conductivity 0.015W/(m・K) , temperature resistance 650 ℃) is used with a thickness of only 10-20mm , which is equivalent to the insulation effect of 100mm traditional rock wool and saves 60% of installation space .
Heat insulation treatment of joints and bolts
The joints of the tank body are filled with labyrinth seals and ceramic fiber ropes (12mm in diameter) to avoid thermal bridge effects.
The fixing bolts use ceramic-coated stainless steel bolts (such as 304SS with a coating thickness of 50μm ), and the thermal conductivity is reduced from 16W/(m・K) to 2W/(m・K) , and the contact point temperature is reduced by more than 80 ℃.
3. Active cooling auxiliary device
Circulating water cooling system
Weld a spiral water cooling pipe (φ25×2mm stainless steel pipe) on the outside of the tank, with a flow rate of 1.5-2m/s, water inlet temperature ≤30℃, and water outlet temperature ≤60℃, which can control the surface temperature of the tank within 80℃;
Energy-saving design: Plate heat exchanger is used to recover waste heat for preheating process water, with a heat recovery rate of 40%.
Forced air cooling system
Axial flow fans (air volume 2000m³/h, air pressure 500Pa) are arranged every 2m along the length of the tank to blow normal temperature air (25℃) to form an air curtain, reducing the surface temperature by 20-30℃;
Cooperate with temperature sensor (accuracy ±1℃) to automatically start and stop the fan. It starts when the surface temperature of the tank is greater than 70℃ and stops when it is less than 50℃. The energy consumption is reduced by 55% compared with continuous operation.
Anti-scalding coating and safety signs
The outer layer is wrapped with glass fiber anti-scalding cloth (surface temperature ≤ 45°C) and painted with warning color (such as bright red). Heat insulation baffles (thickness 3mm aluminum-magnesium alloy + 20mm aerogel) are installed at key positions (such as drive section and transfer point). The protection distance is ≥ 800mm;
An infrared thermal imager (accuracy ±2°C) is installed to monitor the surface temperature field in real time, and over-temperature areas are highlighted in red on the HMI interface as an early warning.
4. Scenario-based application cases
Metallurgical industry: When conveying 1000℃ steel slag, the combination of "310S inner layer + ceramic fiber blanket + circulating water cooling" is used, and the outer surface temperature is reduced from 500℃ in the exposed state to 65℃, meeting the occupational health and safety standards (GBZ 2.2-2007);
Food drying line: When conveying 80℃ roasted coffee beans, aerogel felt + forced air cooling is used, and the surface temperature of the trough is controlled at 35℃ to avoid burns to personnel and prevent the increase in ambient temperature from affecting the humidity of the workshop (RH≤60%).
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