Centrifugal fanIt is a machine that relies on input mechanical energy to increase gas pressure and discharge gas, a type of fluid machine. It is related to the working characteristics of ventilation, dust removal, and pneumatic conveying network systems, which not only concern the performance of the fan but also the performance of the pipeline system.

　　Principle of centrifugal fan: When the impeller rotates with the hinge, the gas between the blades also rotates with the impeller to gain inertial centrifugal force, causing the gas to exit from the outlet between the blades. The expelled gas is pushed into the casing, increasing the gas pressure inside the casing, and is finally discharged through the guide outlet. After the gas is expelled, the pressure in the center of the impeller decreases. External gas can be drawn in through the hole in the center of the impeller front plate at the blower's intake, continuously delivering gas.

　　The pipeline system is a general term for the ventilation, dust removal, and pneumatic conveying pipelines, fittings, and main components (such as vacuum hoods, feeders, elbows, tees, valves, separators, dust collectors, etc.). Only by meeting the requirements of total airflow and total resistance of the pipeline system can the airflow and pressure provided by the centrifugal fan function normally for ventilation, dust removal, and pneumatic conveying. The intersection of the total airflow and total resistance of the pipeline system with the airflow and pressure performance provided by the centrifugal fan is the working point of the fan. In practical operation, the working point of the centrifugal fan sometimes needs to be adjusted appropriately according to production requirements to ensure a relative balance between the output airflow and the actual required airflow.Centrifugal fanThe adjustment of the working point of the centrifugal fan is usually done using two basic methods:

　　1. Speed regulation of the centrifugal fan

　　Adjusting the fan speed means that the characteristics of the pipeline system remain unchanged while changing the fan speed, resulting in changes in pressure, airflow, and power, thus achieving the adjustment purpose. In other words, when the fan speed increases, the airflow and pressure will also increase accordingly. When the fan speed decreases, the airflow and pressure will decrease accordingly to meet the pipeline system's requirements for airflow and pressure. This adjustment method does not incur additional energy loss as the power consumed by the blower varies with actual demand, making it economically favorable. If the fan uses a motor that cannot change speed, a speed-changing device can be installed between the motor and the fan.

　　2.Centrifugal fanThrottle adjustment of the pipeline system

　　Throttle adjustment of the pipeline system refers to installing a throttle valve or flap on the fan's intake or exhaust pipe, adjusting the opening degree of the throttle valve or flap according to actual needs, thereby changing the characteristics of the pipeline system. In other words, if the throttle valve or flap is opened widely, the airflow will increase, and the pressure will decrease. If the throttle valve or flap is opened slightly, the airflow will decrease, and the pressure will increase. The additional energy loss caused by small gate valves is obviously lower than the cost of changing the fan speed, but this method is simple and more widely used in actual production sites.