RECIPROCATING AND ROTARY COMPRESSORS

https://www.mesubjects.net/wp-admin/post.php?post=7656&action=edit      Steam engines

https://www.mesubjects.net/wp-admin/post.php?post=7801&action=edit     Centri and Axial compressors

https://www.mesubjects.net/wp-admin/post.php?post=7649&action=edit      Air compressors

https://www.mesubjects.net/wp-admin/post.php?post=7344&action=edit       Fill Blanks-compressor

https://www.mesubjects.net/wp-admin/post.php?post=6740&action=edit      Refri Reciprocating compressors

RECIPROCATING AND ROTARY COMPRESSORS

Sr.

No.

ASPECT RECIPROCATING COMPRESSORS ROTARY COMPRESSORS
1. Physical motion These employ piston cylinder device with to and fro motion. These employ an impeller with rotary motion.
2. Pressure rise per stage Discharge pressure is high and gives a pressure ratio of 4 to 7 per stage. Discharge pressure is low and gives a pressure ratio of 3 to 5 per stage.
3. Pressure range and discharge Used for high pressure and less volumetric flow rates. Used for less pressure rise  and large volumetric flow rates.
4. Upper limit of high pressure These can produce pressures up to 1000 bars Normally these produce pressures up to 10 bars. With large number of stages, these can produce pressures up to 400 bars.
5. Volumetric flow rate or capacity These can handle volume flow rate of 50 m3/sec. Centrifugal compressors can handle volume flow rate of 500 m3/sec and Axial flow compressors can handle volume flow rate of 1500 m3/sec.
6. Speed These run at low RPM. These run at high RPM.
7. Gas supply These need a receiver as these give an intermittent supply of compressed gas. These do not require a receiver as these supply compressed gas at a uniform rate.

 

8. Lubrication Lubrication system is complex. Lubrication system is simple.
9. Unit size These are bigger in size for a certain flow rate. These are relatively more compact.
10. Unit weight These are having a heavy structure. These are of light structure.
11. Stability There are vibrations and hence there are frequent balancing problems. There are no balancing problems.
12. Repair and maintenance Their repair and maintenance is more as well as expensive. Their repair and maintenance is less as well as inexpensive.
13. Purity of compressed gas Compressed gas comes in contact with the lubricating oil and thus gets contaminated. Compressed gas does not come in contact with the lubricating oil and thus is clean.

 

 

14. Ideal efficiency Iso-thermal efficiency is the ideal efficiency because slow speed, cylinder cooling as well as inter-cooling in between the stages Adiabatic efficiency is the ideal efficiency because of highs speed and involving fluid friction.
15. Mechanical efficiency Mechanical efficiency is low because of number of sliding parts. Mechanical efficiency is high because there are no sliding parts.
16. Flexibility Flexibility is possible in flow rate and pressure range. There is no flexibility is possible in flow rate and pressure range.