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The principle of centrifugal Fan

Jun 27, 2018

1.Definition of centrifugal fan

Centrifugal fan is a kind of driven fluid machinery which depends on the input mechanical energy to increase the gas pressure and to discharge the gas side by side. Centrifugal fans are widely used in oil and grease factories, mainly including 1, ventilation and dust removal: used for oil cleaning, meal / skin crushing, ventilation and dust removal in oil / meal conveying process, pneumatic transportation, such as the wind transport of bean peels and the transportation of clay. Skin / kernel air separation, coal ash transport 3, ventilation drying: for example, conditioning tower, expansion material drying / cooling, meal drying / cooling, etc.

2. The principle of centrifugal Fan

When the impeller rotates with the rotating axis, the gas between the blades also obtains the inertial centrifugal force with the rotation of the impeller, and the gas is ejected from the outlet between the blades. The ejected gas is squeezed into the housing, and the pressure inside the housing increases and is eventually directed to the outlet. When the gas is thrown out, the pressure in the center of the impeller decreases. The external gas can be inhaled from the suction inlet of the fan through the orifice in the center of the impeller, and it can be continuously transported.

3. Structure of centrifugal Fan

Centrifugal fan is mainly made up of impeller, casing, inlet, regulating valve and driving device.

Impeller: consists of a front plate, a rear disc and a blade arranged in two plates.

Casing: the shell of the fan is shaped like a volute, welded with thin steel plate, whose function is to collect the gas from the impeller and lead it smoothly to the outlet of the fan along the rotating direction of the impeller, and to increase the pressure of the gas;

Inlet: the first end of the suction section, which acts as a collector, so it is also called a collector.

4. Main performance parameters

Flow rate Q: the amount of fluid carried by the fan per unit time, usually expressed by volume flow, per unit m3 / s or m3 / h, depending on the structure, size and speed of the fan;

Pressure head p: the effective energy provided by the fan to the unit volume flow rate, in units pa.

Efficiency η: in actual operation, due to the existence of various energy losses, the actual (effective) pressure head and flow rate of the fan are lower than the theoretical value, and the input power is higher than the theoretical value. The parameters that reflect the magnitude of energy loss are called efficiency. Efficiency and fan type, size, processing accuracy, gas flow and properties and other factors. Usually, the efficiency of the small fan is 50 / 70, while the large fan can reach 90.

Axis power n and effective power: axis power is the motor input fan shaft power unit w or kw. The effective power of centrifugal fan is the energy obtained by gas from impeller in a unit time, and then there is Ne=Qp,N=Ne/η= Qp/η.

Speed n: the number of revolutions per minute of the fan and fan impeller is called "r/min".http://www.jnblower.com/