screw compressor working and principles

1. A PRESENTATION ON
SCREW TYPE AIR COMPRESSOR
Submitted by :
Pankaj Sarma - M-55/14
Subhabrata Roy - M-53/14
Chiranjib Borah - M-94/14
Lalremruata - M-91/14
Mechanical Engineering Department
Jorhat Engineering College,

2. Contents:
Introduction
Classification of air compressors
Screw type compressor
Application of screw compressor
References

3. Introduction
An air compressor is a mechanical
device that increases the pressure of air
by reducing the volume.
The compressed air is stored in the air
receiver tank and can be used for
different purposes. When tank pressure
reaches its lower limit, the air
compressor turns on again and re-
pressurizes the tank.

4. Classifications of air
compressors

5. Types of compressors
Air compressors are classified
according to method of energy
transfer and pressure generation :
1. Positive displacement
compressors.
2. Dynamic compressors.

8. Screw type air compressor
The screw type compressor uses two
rotors (helical screws) to compress air
namely male rotor and female rotor. The
rotors are of different shape, but fit each
other exactly.

9. Working principle:
 In a screw compressor one of the shaft is
driving shaft and the other is driven shaft.
The two shafts are enclosed in an air tight
casing.
Firstly the suction valve is opened to
allow air suction.
The air enters the gap between the two
screws cut over the shafts. As the two
screws turn in opposite direction the air

11. The gap between the two screws
decreases gradually from suction end to
delivery end, which leads to compression
of air.
 Also due screw action the air moves from
the suction end to the delivery end.
When the compressed air reaches the
delivery end, it passes through the
delivery valve to the storage tank.

13. Types of screw compressor
Two types of screw compressors are there
namely:
1. Oil injected compressor: Here, oil is
injected in the compressor element
(where the actual compression takes
place) during the compression of the air.
This oil is later removed by the oil
separator, so we end up with clean
compressed air. This helps in reduction
of friction and also helps to dissipate the
heat generated.

14. Advantages:
Quiet operation.
High volume of air, steady flow.
Lower energy cost (compared to
piston-type compressors of the same
size).
Suitable for continuous operation
(24/7).

15. Disadvantages:
Expensive compared to piston
compressors.
Not suitable for long stand-stills.
Oil carry-over (99.9% oil free air).

16. 2. Oil free compressor: Here, there is no
use of lubricating oil. Because there’s
no oil injected during compression. The
compression is usually done in two
stages. Because if we would compress
the air in one go from 1 to 7 bars, it
would get very hot. The air delivered is
100% oil-free.
They are mostly use in medical
research and semiconductor

17. Advantages:
100% oil-free air
Quiet operation
High volume of air, steady flow.
Lower energy cost (compared to
piston-type compressors of the same
size)
Suitable for continuous operation

18. Disadvantages:
More expensive than oil-injected
type.
Servicing/repairing more difficult,
and more
expensive than oil-injected type.
More noise than oil-injected
compressors.

19. Applications of screw
compressor
They are commonly used to
replace piston compressors where
large volumes of high pressure air are
needed, either for large industrial
applications or to operate high-power
air tools.

20. Industrial Applications:
1.Metallurgy and Mining
2.Papermaking and Printing
3. Medicine and Health
4. Household Appliance
5. Electronic and Electrical
6.Transportation

21. 7. Light Industry and Food
8. Textile and Clothing
9. Electric Power
10. Construction and Building
Material

23. References
 Books: Applied thermodynamics, P.K.Nag
 Web:
1. http://www.air-compressor-
guide.com/learn/compressor-types/rotary-screw-
compressor.
2. https://www.quora.com/What-is-the-working-
principle-of-screw-compressor
3.http://www.rotorcompressor.com/application.htm
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24. Thank You…