4 replies to this topic

[krishnamurthy]

Currently I am working in a PSV sizing case (WETTED WALL) which handles NGL liquid (Natural Gas Liquid)service. This PSV is mounted on a filter separator. The operating conditions of the vessel is as below

 

1. Operating/Design Temp :   35°C / 50°C

2. Operating/Design Pressure: 70 bara / 101 bara

 

Using conventional methods in hysys for finding relieving temperature, I am getting an error message in hysys saying "Stream temperaure could not be found at the specified conditions".

 

I need help in sizing PSV in the above mentioned scenario for finding the RELIEVING TEMPERATURE.

 

Please also advice whether the relieving temperature shall always be above the design temperature.

[oscarsender]

Hi

 

the fluid may be beyond critical point at that condition. please refer to the link below for the same forum discussion. otherwise please use search function in this site for other related posts.

 

http://www.cheresour...062-psv-sizing/

[fallah]

Hi,

 

As oscarsender mentioned error message may be due to the relieving conditions to be beyond critical point. Is so, you can treat the fluid as a dense gas and solve for finding the relieving temperature at specified relieving pressure.

 

In the scenarios other than fire the relieving temperature should always be lower than design pressure; but in fire scenario the relieving temperature can be either lower or higher than design pressure...

Edited by fallah, 12 August 2014 - 12:38 PM.

[Pumumu]

For PSV scenario other than fire, I usually use value that is same with setting temperature, is that correct??

[fallah]

Pumumu,

 

What do you mean by "setting temperature"?