ROTARY COMPRESSORS

This is a presentation on rotary compressors which is a part of fluid power engineering.

1. Prepared by : Kunj Thummar Sumit Patel Jasvant Maliwad Gunjan Vasava COMPRESSORS

2. What is a compressor ? It is a machine which takes air or any other type of gas at low pressure and compresses it to a high pressure.

3. CLASSIFICATION

4. ROTARY COMPRESSORS Rotary compressor is a mechanical device which is used for delivering large quantity of air up to pressure of 10 bar with continuous flow. Different types of rotary compressors are as follows :

5. Positive displacement rotary compressors : In these compressors air/gas is compressed by trapping it in a reducing passage formed by a set of engaging surfaces. The gas pull from suction side and push to delivery side by the help of engaging surfaces. Roto dynamic rotary compressors : in these type of compressors, the compression of vapor/gas is carried out by a rotating elements imparting velocity to the flowing gas and developed desired pressure and compression is achieved by dynamic action of rotor.

6. ROOTS BLOWER CONSTRUCTION It contains generally two lobes. It contains a casing inside which there are two shafts fitted with two lobe rotors. One rotor is driven by motor and another by gears.

7. WORKING Air is drawn through inlet pipe due to rotation of rotors. The volume of air is trapped between rotor and casing for a short time interval. Due to rotation of lobes trapped air is carried out to the discharge side. Continued rotation of rotors, opens the trapped space to the discharge part. The air is pushed to the receiver due to the continued rotation of rotor.

8. VANE TYPE BLOWER CONSTRUCTION It contains rotor drum mounted eccentrically in a cylindrical casing. Vanes remain in contact with wall due to centrifugal action. Vanes can slide in and out of the slots.

9. WORKING The rotation of rotor caused space between vanes, the rotor and casing. The space is connected to the suction pipe. In this space the air enters and fills the whole space. With rotation the air gets compressed due to reduction of space towards delivery. The fluid volume is now reduced and communicates with the delivery pipe. Due to pressure difference in compressed air and the receiver pressure back flow of air takes place, which causes further rise in pressure of internally compressed air. This air is now delivered to the receiver.

10. SCREW COMPRESSOR CONSTRUCTION It contains two mating helically grooved rotors. Rotors are suitably housed in a cylinder. Cylinder are equipped with appropriate suction and discharge ports. Rotors are driven by synchronized gears.

11. WORKING Gas enters from the suction side and progressively gets compressed as it moves through the narrowing passage formed by lobes. Compression is obtained by following stages : Suction Transportation Compression Discharge

12. SCROLL COMPRESSOR CONSTRUCTION It contains two matching scrolls. One of them is fixed and other free to orbit. These scrolls form series of space packets between two mounting spirals. These spaces are filled by gases while in working condition. Suction take space at outer edge and delivery for center fixed port.

13. WORKING When shaft rotates the orbiting scroll open the suction port. Gas enters in the space created. Further rotation of shaft reduces the gas pocket area hence increasing the pressure. At the end of third revolution thee gas is delivered out for delivery port.

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