Can centrifugal fan replace Roots fan?

Answer: No.

Can centrifugal fan replace Roots fan?

The answer is: No.

What is the difference between Roots blower and centrifugal blower and Roots blower?

1、 Situation analysis

There are fans on many equipment in the power plant. Many operators do not know Roots fans and centrifugal fans very well, and they are often referred to as fans.

Roots blower: Roots blower is a volumetric fan, and the air volume transported is proportional to the number of revolutions. There is always a small gap between the end face of the impeller, between the front and rear end covers of the fan, and between the fan impellers. Under the drive of the synchronous gear, the air is transported from the air inlet of the fan to the exhaust side along the inner wall of the housing.

Centrifugal fan: centrifugal fan is a driven fluid machine that relies on the input mechanical energy to increase gas pressure and discharge gas. Centrifugal fans are widely used for ventilation, dust removal and cooling of factories, mines, tunnels, cooling towers, vehicles, ships and buildings, and for ventilation and induced draft of boilers and industrial furnaces.

2、 Difference between Roots blower and centrifugal blower

(1) The working principle is different. The centrifugal fan uses curved blades, and the gas is thrown to the casing by centrifugal force, while the Roots fan uses two 8-shaped blades, and the gap between them is very small. The gas is squeezed to the air outlet by the extrusion of two blades.

(2) The outlet pressure is different. Due to different working principles, their working pressures are generally different. The outlet pressure of Roots blower is relatively high, while that of centrifugal blower is relatively small.

(3) The air volume is different. Generally, Roots blower is used in places with low air volume requirements but high pressure requirements, while centrifugal blower is used in places with low pressure requirements and high air volume requirements.

(4) The manufacturing precision is different. Roots blower requires high precision and strict assembly requirements, while the assembly requirements for centrifugal blower are relatively loose.

3、 Fans commonly used in wastewater treatment

(1) If the load needs constant flow effect, use Roots blower. Because Roots blower is a constant flow fan, the main working parameter is the air volume, and the output pressure changes with the change of pipe and load, and the air volume changes little. Roots blower is a high pressure, positive displacement fan. The air volume transported is proportional to the number of revolutions, and the gas is transported from the suction side to the discharge side.   

(2) If the load needs constant pressure effect, centrifugal fan is used. Because the centrifugal fan is a constant pressure fan, the main working parameter is the air pressure, and the output air volume changes with the change of the pipeline and load, and the air pressure changes little. Centrifugal fan with low air pressure. The air compression process is usually carried out by several working impellers (or stages) under the action of centrifugal force. Centrifugal fan belongs to square torque characteristic, while Roots fan belongs to constant torque characteristic.

(3) If the required air volume is relatively small and the requirements for noise are relatively high, the rotary fan is selected. The rotary fan is also a constant flow fan. The main working parameter is the air volume. The output pressure changes with the change of the pipe and the load. The air volume changes very little. The rotary fan is a variable volume compression fan. Its main characteristics are: low speed, low vibration, high efficiency, and high energy saving.