The fan capacity is selected according to the maximum air volume required by the process equipment, but the air volume required by the equipment during actual production and operation is sometimes large or sometimes small. Therefore, adjusting the air volume of the fan according to the operation needs is a common method to achieve energy-saving operation of the fan.
There are usually two ways:
(1) control the air valve at the input or output end;
(2) Control the rotation speed of the motor.
Control the air volume by adjusting the opening of the air valve: the manufacturer of the air filter fan tells you that the motor is often used to run at a constant speed in industrial production. The starting method of reducing the load of the fan is by closing the air valve and controlling the air volume by adjusting the opening of the air valve. In this process of air volume regulation, the motor shaft power is proportional to the air volume.
The method of regulating air valves to control air volume has the advantages of less initial investment and simple control, which has been used in industrial production. But its disadvantage is that when the air valve is adjusted to control the air volume, the operating efficiency of the fan equipment is significantly reduced, the power loss is large, and the energy-saving effect is not obvious.
The speed regulation is used to control the air volume: the energy-saving principle of adjusting the air volume by controlling the fan to drive the motor speed is based on the relationship among air volume, pressure, speed, and torque. The air volume is proportional to the speed, and the motor shaft power is proportional to the cubic speed. When the ventilation system only needs half of the air volume, the motor speed can be reduced by 50%, and the motor output power is only 12.5%. Speed control is adopted to control the air volume so that the power loss is minimized and the energy-saving effect is considerable.
The energy-saving method of speed control air volume has an ideal energy-saving effect. The manufacturer of the air filter fan tells you that there are many AC speed regulation methods for the motor, such as pole-changing speed regulation, stator voltage speed regulation, frequency conversion speed regulation, etc. With the development and popularization of frequency conversion technology and the high performance of frequency converter products, the energy saving of fans by using frequency converter speed regulation has gradually replaced the scheme of air valve control.