July 07, 2007

Safeguard your Compressors

Generally almost every industry face the problem of failures / corrosion / pitting in compressors internals due to presence of mainly mositure while handling any gas coming out through a wet system or air.
The Reason

1. Condensation in the line between the separator and the compressor.

2. Liquid from the separator due to fine mist carryover with the gas.

  • For suction line there are two possibilities either to provide good insulation and/or heat traced or to provide a condensate boot with a drain line for intermittent automatic draining through a drain valve which operates on gravity.
  • From generally accepted rules, be sure that the separator is properly sized. If the separator does not include a mesh pad, consider installing one to see if this helps. You also may want to install a mist eliminator in the line leading to the compressor (and change it at least twice a year).
However, my experience with this in case of a reciprocating compressor for CO2 gas is that the design of separator internals are very important aspect for better separation efficiency. Many configurations are possible from easiest one being the downward inlet pipe with baffles or tangential entry to the complex ones as shown in the graphics below.




I have improved the efficiency of our system by first putting a 45° downward angled baffle at the front of inlet pipe, which knocked of most of the mositure/mist by impingement and then channelized the gas flow by reversing its direction 2 times before it passes through mesh pad.

The maintenance frequency for the compressor reduced from 2 months to more than a year.


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