Industrial production often uses centrifugal fans as induced draft fans, because centrifugal fans can achieve high negative pressure and draw out boiler dust or steam, but sometimes there is insufficient air pressure of centrifugal fans, which greatly affects industrial production. What should I do if I press it down?
1)The reason for the small wind pressure of the centrifugal fan
The wind pressure of the centrifugal fan becomes smaller, the main reason is related to the leakage of the fan and the lower power of the motor, and in some cases, it is related to the size of the selected fan:
1. Fan leakage
When the impeller of the centrifugal fan is running, there will be two areas of high pressure and low pressure inside the fan. When the gap between the moving parts and the fixed parts of the centrifugal fan becomes larger, part of the gas will leak from the high pressure area to the low pressure area through the gap. At the same time, when the air flow near the front disc of the volute passes through the gap between the impeller inlet and the air inlet, it will also flow back to the low pressure area of the impeller inlet, resulting in internal leakage loss; in addition, when the gas flows from the centrifugal fan When leakage occurs in the gap between the rotating shaft and the volute, external leakage loss will also be formed. The larger these gaps in the centrifugal fan head, the smaller the wind pressure and air volume, and the lower the efficiency of the fan.
2. Motor power becomes lower
The main kinetic energy of the centrifugal fan comes from the motor, and the speed of the speed also depends on the speed of the motor. The wind pressure of the centrifugal fan is mainly related to the diameter and speed of the impeller. When the speed is too low, the wind pressure will decrease. The motor power is generally determined when the fan is selected. If the power becomes low, it may be related to the grid voltage or the load of the centrifugal fan. If the load is too large, the power of the motor will not be enough to drive the impeller to rotate, resulting in Wind pressure decreases.
3. The fan is not big enough
It has just been introduced that the wind pressure of the centrifugal fan is mainly related to the diameter of the impeller and the rotational speed. Under the condition that the rotational speed can be guaranteed, the larger the diameter of the impeller, the higher the wind pressure generated. If the diameter of the impeller of the centrifugal fan is selected to be small, the wind pressure will be small.
2)the treatment method of centrifugal fan with low wind pressure
1. Reduce the gap
Physical methods can be used to reduce the gap of the centrifugal fan, such as replacing the fan parts or overhauling the equipment, so as to prevent the internal and external leakage of the gas, but this method is too much work, so in many cases, the method of filling glue is used to seal the gap. , Filling super glue evenly in the gap can avoid leakage and restore wind pressure for a long time.
2. Adjust the motor power
Adjusting the number of stages of the motor power can significantly increase the speed of the fan, thereby increasing the wind pressure of the centrifugal fan. If the motor currently used is a 4-pole motor (1450 speed), and the strength of the impeller can meet the requirements of higher speed, the It is adjusted to a 2-pole motor (2800 speed), thereby increasing the air flow rate of the centrifugal fan and the static pressure of the fan.
3. Adjust the size of the impeller blades
By changing the size of the impeller blades, the airflow direction of the suction impeller can be changed, and the performance curve of the centrifugal fan can be changed. The positive winding adjustment of the inlet air flow of the fan can realize all the working conditions below the performance curve when the angle of the inlet guide vane is zero degrees, and the adjustment of the size of the inlet air flow can improve the total pressure and air volume of the fan, but the adjustment range value has a certain limit. .