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Change-out of HP cold recycle valve

Change-out of HP cold recycle valve

Change-out of HP cold recycle valve

(OP)
Hoi ,

Recently we changed out on a two stage compressor the HP cold recycle valve.The new one is faster. They also increased the CV of the valve from Cv 80 to 114. The valve has a double function.: control and anti-surge. We programmed the new curve in our automation system, but tuning is still a problem. Is the choice of a Cv charactiristic for a compressor. Operation envelope enzz.

Thank O.

RE: Change-out of HP cold recycle valve

A faster valve?  Do you mean you went from a linear to a quick open trim?  

What do you mean, two functions? If your set point is away from the surge line, why would you need anti-surge.

Cv doesn't make any difference.  If your process needs a Cv = 50, then a maximum of 80 or 110 doesn't matter unless you have a upset or startup case that requires 90, then the 80 won't work.  

You said you put the curve in the atosystem, you mean the Cv vs the % travel? So EE may explian that one, but I don't see why it has anything to do with the control tuning.

Overall, you have a faster opening valve at the low end where one would expect to be for a antisurge.  this means the loop must be slowed down because a small valve movement will make a huge change in flow when the valve first opens.

Rethink you needs and maybe you need a linear travel with a faster loop?

RE: Change-out of HP cold recycle valve

Maybe try A linear travel?

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