3 Methods for Controlling Airflow in Centrifugal Explosion-Proof Fans

3 Methods for Controlling Airflow in Centrifugal Explosion-Proof Fans

Control via Vibration Dampers in Centrifugal Explosion-Proof Fans. Centrifugal explosion-proof fans typically have a relatively large airflow margin. When using a damper for control, the average opening of the damper is usually around 50. A significant amount of energy is wasted overcoming the damper’s resistance, which reduces the efficiency of the centrifugal explosion-proof fan. At the same time, this can lead to issues that are difficult to control properly, such as unstable pressure within the ductwork network, excessive motor starting current resulting in motor losses, and pressure surges. Hydraulic Coupling Control. A hydraulic coupling is a mechanical speed-adjustment device that consumes energy. The greater the speed reduction (the slower the speed)—especially under constant-torque loads—the greater the losses. Since the input power is constant, power losses increase proportionally with the reduction in speed. In the case of centrifugal explosion-proof fans and pumps, the load torque varies in proportion to the square of the speed; therefore, the input power decreases in proportion to the square of the speed, resulting in relatively small power losses. However, the output power decreases in proportion to the cube of the speed, and the speed regulation efficiency remains very low. The average speed regulation efficiency of a hydraulic coupling is approximately 50%. Frequency control of centrifugal explosion-proof fans. Frequency conversion speed regulation adjusts the airflow of a centrifugal explosion-proof fan by varying the speed of the fan motor. According to the laws of fluid dynamics, there is a relationship between the shaft power p and the fan speed n. If the airflow of a centrifugal explosion-proof fan is reduced from 100 to 50, the efficiency of the fan is 30% higher than that of a damper, on average. Among various control methods, variable frequency drive control offers significant advantages in terms of energy savings and efficiency.