The fan outlet temperature is too high; is external air supply effective?
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Today, the fan in our factory suddenly stopped working, which caused acid gas to backflow and knocked down two people on the spot; they were taken to the hospital. It’s still not clear whether they have regained consciousness... The cause was determined to be an automatic shutdown due to a high temperature at the fan’s outlet. I want to raise the temperature threshold for this shutdown mechanism, but I’m afraid it might damage the fan. Someone suggested blowing air from outside towards the temperature sensing point – I’m not sure if that would work. What do you all think? (By the way, it’s already known that the problem is caused by excessive friction in the fan bearings, but it’s not allowed to stop the fan right now to fix it.)
The bearing has a problem; how much longer can it hold up? If you really can’t stop it, try using cold water from the outside.
Is the temperature measurement point inserted into the pipe at the fan outlet? If so, it’s useless to blow air at the temperature measurement point using an external fan. Is the temperature measurement point used to measure the temperature of the motor bearings? If so, it only treats the symptoms, not the root cause. You can determine the motor load by checking the current. It is recommended that the original poster monitor the current to see if it remains within the rated range; if the current does not exceed the limit even after prolonged operation, it indicates that the load is not heavy, and the likelihood of the motor burning out is low. ——As a temporary solution in emergency situations, one can raise the interlock temperature slightly. From a process perspective, it is not a good practice to disable the interlocks or to change their settings arbitrarily* (our electricians often do this, and it has led to problems); it’s better to identify the cause of the overtemperature before taking appropriate action. Personal opinion, for reference only
Now that the reason has been identified, it should be dealt with promptly! I wonder which genius came up with this idea? ! Actually, there’s no need to worry so much; simply breaking the chain reaction will lead to the same outcome—the fan will get completely damaged! There’s no need to deceive oneself; there’s also chain protection! If it is a risk necessary for handling the accident, then it should be done! Safety first is not just a slogan; safety first is the wealth of a company!
It is normal for the temperature at the fan’s outlet to increase; the higher the outlet pressure, the greater the temperature rise. It is necessary to determine whether the increased temperature at the fan owner’s unit represents a normal increase. If it is a normal increase, then there is no need to worry about the fan being damaged； Gases such as air have very low heat transfer coefficients, resulting in poor blowing performance at the fan outlet. If higher performance is required, it is advisable to install a cooler at the fan outlet, similar to the interstage cooler or aftercooler used at the compressor outlet.
First, the cause of the excessive temperature should be identified. Also, the original poster didn’t clarify whether it was the temperature of the medium that was too high or the temperature of the moving parts that was too high. So it’s necessary to first find out the cause before taking appropriate action. Is blowing air useful? It is certainly useful for lowering the temperature of the medium, though its effect is not very significant.
A coil radiator can be added to the air outlet; it functions similarly to the surface cooler inside the air handling unit. Cooling water is fed into this surface cooler, and valves are used to control the flow rate thereby regulating the temperature, while the air is directed using guide ducts
Since it’s clear that there’s a problem with the fan bearings, it’s better to stop and replace them – after all, safety comes first; two people have already been injured! Human life is of paramount importance; the chain will not break in such a situation, but what if the bearings burn out and cause the vehicle to derail? Will we still be that lucky and only need to knock out 2 people?
Upgrading equipment is a matter of life and death. Don’t risk your life for money either: L
Get the spare parts ready quickly, otherwise we’ll be in a difficult situation if the motor gets completely damaged. By the way, apply some lubricant to the bearings. One more thing: don’t you have any fire barriers or something in your ductwork? Logically, after the fans stop operating as a result of the interlock mechanism, those barriers should also drop down, so that the acidic gases can’t flow back in. More importantly, employees must have the necessary emergency PPE. An activated carbon filter cartridge costs over 100, and equipping one person with such equipment costs at least 200,000; it’s worth investing in safety measures.
Personally, I believe that safety comes first above everything else; safety must be ensured first and foremost. You can’t lose the big picture for a small gain! ! Even though businesses are facing difficulties in operations, they can’t take employees’ lives lightly – the fans need to be repaired right away.