The return fan, suction fan, and suction fan must use Roots blowers.

The return fan, suction fan, and suction fan must use Roots blowers. The difference between Roots blowers and centrifugal fans:
Roots blowers are positive displacement fans and have similar principles to gear pumps (I think of them as pumps) .
Centrifugal fans use high-speed rotating impellers to accelerate and then decelerate the gas, changing the flow direction to convert kinetic energy into potential energy.
Which is more suitable for industrial boiler return material? The following is a personal opinion for reference:
The advantage of a centrifugal fan as a return material device is that it is easy to control the air volume. The disadvantage is that it is difficult to raise the wind pressure too high and stabilize it. It feels like the motor is more powerful than the Roots blower. If the outlet is closed too small, the pressure will cause vibration or the outlet pipe will be hot (this phenomenon is very obvious in gas compressor applications and can be controlled within a certain range by adjusting the balance valve).
The return Roots blower is different from the centrifugal fan. If the outlet of the Roots blower is over-pressured, the motor will trip over current. Generally, the exhaust valve at the fan outlet is adjusted to set the pressure control current. But for safety, Roots blower is better.
Generally, small boilers use the primary fan pipe as the return fan. Larger boilers mostly use Roots blowers.
So if you still use centrifugal fans for industrial boiler material return, it is recommended to contact our East China fan manufacturer to consider replacing them with Roots fans.