6. ANTISURGE PROTECTION SYSTEM

 Antisurge control has the job of maintaining the compressor in a stable operating range assuring a higher suction capacity than the surging rate, whatever the compression ratio may be.

Let us take a p,Q1 diagram (compression-suction capacity ratio): ideally the regulation line should be parallel and lightly to the right of the actual surge line (see figure. 6.1).

Any adjustment will be based on the measure of the capacity passing through the machine or will depend, as a rule, on other physical variables so that regulations may meet the following basic requirements:

1.  The regulation line should be as close as possible to the surge limit line moved parallel to the capacity axis by an established amount (figure. 6.1).
2. When conditions of the suction fluid vary, the regulation line should not get any closer to the surge line, relating to the design conditions, than may be necessary for proper operation of the antisurge system.
3. The system protects the machinery in all possible operating, start-up and standstill conditions.

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