Why are centrifugal fans always placed at the back of exhaust towers? !
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Isn’t it more advantageous to place the centrifugal fan at the front in order to absorb and capture waste gas impurities? !
It provides the driving force for flow, keeping the medium behind it cleaner.
The fan outlet is under pressure; the fan is located at the back of the tower, and the waste gas is discharged directly through pipes to the chimney. If the fan is placed at the front of the tower, then the absorption tower operates under positive pressure, and poor sealing can lead to leaks (absorption towers generally operate under slight negative pressure)
It makes sense for the fan to be far away from the untreated exhaust gas; it indicates that the two are not suitable to be together. To find the cause in the exhaust gases: is it too high a temperature, corrosion, abrasion, or the risk of toxic substances leaking?
It is best for the exhaust system to operate under a slight negative pressure; this prevents any significant release of odors at the site in case there are leaks in the exhaust system； On the other hand, if your exhaust system is connected to a vacuum system or similar, an excessive reserve pressure can affect the operation of the vacuum equipment ；
The outlet pressure of a centrifugal fan is only 2–3 KPa, which is very low, so the possibility of air leakage is minimal. .
From the perspective of absorption principles, positive pressure operation is favorable for absorption. .
The technical manual for wet flue gas desulfurization states that fans are generally placed before the waste gas tower (desulfurization tower)； Desulfurization towers are generally operated under positive pressure ； Putting what you said at the back isn’t impossible ； Considering factors such as the temperature and corrosiveness of the flue gas, it can also be placed behind the tower
The fan is placed at the back mainly for maintenance purposes, allowing for online repairs in case of any issues