Talking about the Method of Adjusting Fan Air Volume

The capacity of the fan is selected according to the maximum air flow required by the process equipment, but the air volume required for the actual production and operation of the equipment is large and small. Therefore, adjusting the air volume of the fan according to the operation needs is a common method for realizing the energy-saving operation of the fan. Usually, there are the following two methods: controlling the air valve at the input or output side; controlling the rotation speed of the motor.

 

    The air volume is controlled by adjusting the opening degree of the air valve: In the industrial production, the motor is often used at a constant speed, and the air valve is used to reduce the starting method of the fan load and the opening degree of the air valve is controlled to control the air volume. In this process of adjusting the air volume, the motor shaft power is proportional to the air volume. The advantage of the method of adjusting the air volume by adjusting the air valve is that the initial investment is small and the control is simple. It is a method that has been used in industrial production. However, the disadvantage is that when the air valve is adjusted to control the air volume, the operation efficiency of the fan equipment is significantly reduced, the power loss is large, and the energy saving effect is not obvious.

   

    Using speed control to control air volume: The principle of energy saving is to use the relationship between air volume, pressure, rotation speed, and torque based on the relationship between wind speed, motor speed, and torque. The power of the motor shaft is proportional to the cube of the speed. When the ventilation system only requires half the air volume, the motor speed can be reduced by 50%, and the motor output power is only 12.5%. The use of control speed to control the air volume, so that the lowest power loss, energy-saving effect is considerable.

 

    The energy-saving effect of the energy-saving method using the speed control air volume is ideal. There are a variety of motor AC speed control methods, such as variable pole speed control, stator voltage speed control, frequency conversion speed control and so on. With the development and popularization of frequency conversion technology, the inverter products have high performance, and adopting frequency converter to realize energy-saving of fans has gradually replaced the air valve control program.