Publish Time: 2022-10-11 Origin: Site
The centrifugal fan is a driven fluid machine that relies on the input mechanical energy to increase the gas pressure and discharge gas. Centrifugal fans are widely used in oil plants, mainly including: 1. ventilation and dust removal: used for oil cleaning, meal/skin crushing, and ventilation and dust removal during oil/meal transportation; 2. Pneumatic transportation: such as the wind transportation of bean skin, the transportation of clay, the wind separation of skin/kernel, and the transportation of coal ash; 3. Ventilation and drying: such as induced air of conditioning tower, drying/cooling of expanded materials, drying/cooling of meal, etc.
When the impeller rotates with the shaft, the gas between the blades will also obtain inertial centrifugal force with the impeller rotation, and the gas will be thrown out from the outlet between the blades. The thrown gas is squeezed into the casing, so the gas pressure in the casing increases and is finally directed to the outlet for discharge. After the gas is thrown out, the pressure in the central part of the impeller decreases. The external gas can be inhaled from the suction port of the fan through the hole in the center of the front disc of the impeller, and the gas can be continuously transmitted.
The centrifugal fan is mainly composed of impeller, casing, air inlet, regulating damper and driving device.
Impeller: composed of front disc, rear disc and blades installed between two discs;
Casing: the casing of the fan is volute shaped, welded with thin steel plates, which is used to collect the gas from the impeller and make it smoothly led to the outlet of the fan along the direction of impeller rotation, and pressurize the gas;
Air inlet: the head part of the suction pipe section, which plays the role of gas gathering, is also called a collector.
Flow Q: the amount of fluid transported by the fan in unit time, usually expressed by volume flow, in m3/s or m3/h, related to the structure, size and speed of the fan;
Pressure head p: effective energy provided by fan for unit volume flow, in pa;
efficiency η： During the actual operation of the fan, due to various energy losses
The actual (effective) head and flow are lower than the theoretical value, while the input power is higher than the theoretical value. The parameter reflecting the magnitude of energy loss is called efficiency. The efficiency is related to the type, size, processing accuracy, gas flow and nature of the fan. Generally, the efficiency of small fans is 50%~70%, while that of large fans can reach 90%;
Shaft power N and effective power Ne: shaft power is the power of motor input fan shaft, in W or kW. The effective power of centrifugal fan refers to the energy obtained by the gas from the impeller in unit time, so there are Ne=Qp, N=Ne/ η= Qp/ η。
Rotating speed n: the number of revolutions per minute of fan and fan impeller, namely "r/min".