Hot gas by pass valve for compressor

[rotw]

Hi,

I would like to know if a hot gas by pass valve is controlled from the anti-surge controller /PLC in the same way as the cold by pass anti-surge valve ?
Is there a dedicated algorithm for hot gas by pass valve and are the same input used (PT, TT at the compressor inlet and outlet and Flow Transmitter) ?
Can it be adapted and used for both trip/start up and limited continuous operation if the delta T due to absence of cooler acceptable ?

Thanks

 

[dcasto]

The hot gas by-pass will increase ACFM quicker and centrifugals need acfm. The control system is the same hot or cold. If the amount of hot gas is large, then the suction temperature will rise and the discharge temperature will rise and the unit will shutdown as the discharge temp will some exceed the mechanical limits of the equipment.

 

[rotw]

Thks dcasto
So same PLC take care of hgbv
Same philosophy for protection (surge protection line etc)
?

 

[rotw]

It seems the HGBV is an on/off valve to protect compressor during trip. The two modes should be Full open during trip and closed during start up (to prevent increase of temperature when operating in recycle mode as dcasto mentionned).
Therefore I assume it obeys to a different control logic than the Anti-surge valve.
The valve should go full open if there is a trip signal so If I am correct, the control is not necessary based on surge detection algorithms.