Axial Control Valve Sizing

[neroverdi41]

Hello

I need to make Axial Control Valve sizing for a line with a size of 16”.
Parameters:
P1=82-36 bar
P2=82-36 bar
Q=10000-100000 sm3/h
T=15 C

How can I size it? Also, why are two different pressure values given for inlet and outlet?
Can you help me urgently?

 

[neroverdi41]

It's flow velocity, not flow rate, but I just did a very simple calculation.

100000scmh (highest flow) is 27.7 smc/sec

Allowing for ideal gas, that turns into 0.77 actaul m3/sec (acms) at 36 bar
16" pipe internal area is approx 0.118 m2, so 1m is 0.118m3/m.

So velocity is 0.77 / 0.118 = 6.5m/sec. MAX. That's really very low for a gas flow velocity.

Min veleocity is going to be about 20 times less (10,000 scmh @ 82 bar, which is very very low.

Normally flow velocity inside a control valve is a lot higher than in the main pipe, so in your case my guess is you need something like a 10" or 8" control valve in order to get the range of CV you need.

at first I chose 10“ but due to the deadline we had a 12” valve ready. that's why I chose it. they want the speed especially low. then I thought I would lower the cv value with the cage design. that's why I asked about CFD in another topic.

 

[georgeverghese]

The turndown case will also have to be accommodated, which I guess is : P1 = 82barg,P2=36bar, Q=10e3sm3/hr. The resulting Cv must be higher than the min permissible Cv as recommended by the control valve vendor. From this table, say for 12inch valve, the min Cv for the case of equal %, multipath cage type, for example, is 11(where max Cv at 100% open is 1875).

What Cv do you get for min flow / turndown ?

https://www.emerson.com/documents/automation/data-sheets-type-flv-axial-control-valve-tartarini-en-en-6634658.pdf