The thermocouple sleeves often break; please help analyze the reasons and suggest improvement methods
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The material of the thermocouple sleeve is corundum; its purity level is not well known. The temperature inside the furnace is around 1000°C. The sleeve is completely sealed during installation, but it often breaks down during use.
Sulfur furnaces can reach temperatures of over 1300 degrees. With so many sulfur production furnaces around the world, in a operation cycle of 3 to 4 years, less than half of them will experience problems with their thermocouples. First, its insertion hole must not be tilted; second, it is the quality of the protective tube itself; third, cooling (backflow) air is usually provided inside the protective tube.
Corundum cannot withstand sudden changes in temperature, is not wear-resistant, cannot tolerate pressure, and is fragile. Think about why it broke, so that you can find the right solution.
1. Corundum-based materials can withstand high temperatures, but they have poor resistance to thermal shock; it is therefore necessary to minimize the rate of temperature change during operation. 2. Corundum-based materials possess high hardness and wear resistance, although their strength under bending loads is somewhat limited. The thermocouple is mounted in a cantilever configuration; as its length increases, its resistance to bending decreases. Pulsations in the flow of the medium within the device are also detrimental to corundum. 3 Increasing the purity of corundum and the thickness of the casing, as well as reducing the length if possible, can help improve stiffness. 4 Use reliable suppliers to minimize impurities in the raw materials, ensure thorough and uniform high-temperature sintering, and maintain an appropriate sintering time
It is recommended to consider troubleshooting from three aspects: insertion depth, angle, and vibration; the standard installation diagrams and relevant requirements should be reviewed again.
Can it still be accurate with the cooling air temperature set?
You’ll have to discuss this with the manufacturer; consider whether metal or non-metal materials are more suitable – there are many options available. Also, if possible, try to shorten the length of the sleeve.
Are you using it in a sulfur furnace? It can only be corundum; metals cannot be used. Have the manufacturer do some calculations for you to reduce the depth and increase the diameter
3039 can handle 1300 degrees; if metal cannot be used, then grade 99 corundum should be used. However, many products available these days are of poor purity – for example, those from Tangshan – and the furnaces used there are of average quality; as for small factories, it’s unclear what the quality of their products is. Grade 95 corundum results in lower temperatures. If interruptions occur frequently, it’s better to install it vertically rather than horizontally; moreover, there should be no vibrations, and the temperature should be uniform (this is quite important – sometimes people install it near a stove, and when the door is opened to feed material, uneven temperatures can occur). 1000 degrees shouldn’t be a problem. Come to me to buy the sleeve; it’s not expensive anyway. I think we’ve done a great job
The wind only flows from the flange opening to the inside of the furnace wall