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Psv Inlet Outlet Size Quick Estimation

psv size inlet outlet psv

4 replies to this topic
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#1 rs20170808@gmail.com

rs20170808@gmail.com

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Posted 22 June 2021 - 01:29 AM

Hello everyone I have listed below some steps for calculating preliminary psv inlet/outlet size for blocked flow for single phase gas

Blocked flow case for gas â€¦conventional PSV with set pressure at 150 psig. Constant superimposed backpressure is 2 psig.

• Simulate the gas stream at relieving pressure (1.1 x Set Pressure) and relieving temperature and obtain properties from HYSYS
• Check inlet line size for pr. Drop to be <= 3% of set pressure
• Use a valve in HYSYS and drop pressure from 1.1 x Set Pressure at upstream to 10% of built up back pressure + constant superimposed backpressure (2psig here). Hence flash from 165 psig to 17 psig.
• The properties obtained from HYSYS at 17 psig is above step is to be used for outlet line sizing
• Check tailpipe size for 0.7 Mach and rhov2 criteria and size appropriately

#2 Bobby Strain

Bobby Strain

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Posted 22 June 2021 - 09:42 AM

Why would anyone need to do this? Of course, not everyone has HYSYS.

Bobby

#3 rs20170808@gmail.com

rs20170808@gmail.com

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Posted 22 June 2021 - 10:37 AM

Why would anyone need to do this? Of course, not everyone has HYSYS.

Bobby

Hi Bobby... without process simulator how would one estimate the properties at relieving pressure and downstream of psv??

#4 latexman

latexman

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Posted 22 June 2021 - 10:48 AM

I use Aspen + and PSV's are sized in a Safety Analysis area/environment.  The inlet and outlet pressure drops are calculated when one characterizes the inlet and outlet pipe and fittings and the conditions.  No need to generate properties, the software uses the models that were already configured.  Doesn't HYSYS have similar?

#5 breizh

breizh

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Posted 22 June 2021 - 08:31 PM

Hi,

You may use these resources to support your calculation .

Good luck .

Breizh