Vane compressors are one type of rotary displacement compressors
The rotor of vane compressors is eccentrically mounted relative to the axis of the casing. Longitudinal slots for holding the vanes are cut into this rotor. Upon rotation, the centrifugal force presses the vanes against the internal wall of the housing.
Trailing rings is formed by the service liquid rotating concentrically to the axis of the casing, around the periphery of the impeller rotor. The internal diameter of the trailing rings used, is made somewhat smaller than the internal cylinder or housing diameter. Vane compressors exist in oil lubricated and oil flooded designs. In both cases, the compressor oil serves not only for lubrication but also as a sealant between individual vanes and the housing inner wall.
Oil flooded vane compressors
For oil flooded vane compressors, a considerable amount of oil is introduced into the compression chamber. This amount of oil is used to conduct away the heat generated by compression so that the compressor output temperature amounts to only about 80-90°C. The injected oil is filtered through separators after compression and channeled back to the circuit after separation.
oil lubricated vane compressors
On the other hand, for oil lubricated vane compressors, compressor output temperature reaches very high temperatures in the compression chamber, depending on the final pressure. Compression causes the compressor oils to crack to such an extent that the oil residues in the compressed air may still be filtered out, however, only at the expense of reduced service life time of the downstream filter elements.
How does the vane work
The individual vanes, manufactured either from phenolic resin impregnated plastics or hardened steel, form cells within the rotor which, upon rotation, expand on one side and shrink on the other. On the intake side, the ambient air is drawn in through the enlargement of the cells and, through further rotation, conveyed to the pressure side. There, shrinking of the cells leads to continuous compression of the air.
Compact units of vane compressors
Vane compressors are supplied as ready to connect compact units. These single-stage, single shaft compressors can be installed without foundations. This type of compressor is usually fully equipped with aftercooler, separator and all necessary safety devices. Compressors of this design have no valves but, are fitted with an output control adapted to the desired output pressure.
Power consumption of vane compressors
The power consumption of the drive motor is harmonized with the operating conditions. The less the compressed air is consumed, the more the system pressure rises. Once the high pressure limit value is reached, the regulating system opens an integrated discharge valve and the pressure in the compressor falls to low pressure limit.
Connection of vane compressors
The compressor is separated from the distribution network of points of use by a check valve. On the intake side, the drawn in volume is set to the lowest value through restriction. The compressor now operates in a closed circuit or idle running, with minimum power consumption, which amounts to about 22% of the nominal consumption. Vane compressors, whether air or water cooled, find diminishing use for industrial applications. Maximum pressure is usually up to 10 bar gauge. The output is suitable for medium requirements.
