compressor discharge controller

[khokho99]

Good morning / evening ,



We have for PYGAS unit twin rotary compressor for recovery the hydrogen , the discharge controller maintain the discharge flow 7 tons , in case emergency we loss the hydrogen & the compressor be under circulation , the discharge controller if Auto will close to maintain the pressure & the discharge flow will come down & will trip the compressor . I have suggestion to install minimum close limit 50% for discharge controller .

Any advised will be appreciated.

 

[LittleInch]

Errr, if there is no hydrogen to compress which is why the compressor goes into recycle, how will keeping the discharge valve open work?

Why is your compressor tripping on recycle (I assume this is what you mean by "under recirculation?)

A sketch or schematic always helps to understand your situation and ask questions

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[georgeverghese]

Standard approach is to install a recycle line and control valve around the compressor to handle this case. The recycle valve works through a select switch to operate on the more demanding deviation, which may be either the high set discharge pressure controller or the low set suction pressure controller. The case you describe is handled by the low set pressure controller. Pls see standard capacity control scheme for fixed speed compressors - this capacity control scheme is used for positive displacement compressors also, like this one. Talk to your plant control systems engineer who may be able to help if you are not familiar with this suggested scheme.