2 replies to this topic

[runsaep]

The PSV module also contains a line sizing feature, but my experience is that this is presently imperfect. It refers to a "inlet line" and a "outlet line" ;and as such is only capable of sizing the nearest, adjacent pipe on both sides of the PSV. My inlet configuration consisted of two 18" relief lines from the vessel combined to a 24" inlet header before branching off to 5 off 12" inlet lines to the PSV's. Such a pipe configuration could not be modelled by the line sizing feature, so I had to utilize the pipe segments option in Hysys - building individual pipe segments and connecting them together. I have reported my observation to Aspentech.

 

 

[aqassam]

Can you provide a sketch of the inlet line to the PSV? How common is this type of inlet piping configuration? I'm a new engineer and have yet to see such a configuration. I would be interested to see if Hysys could manage to simulate something like this. Currently the PSV module works in terms of equivalent length to calculate the delta P along the line. 

[runsaep]

Another observation is that on the lower right corner of the line sizing window you find two columns denoted #Pieces PSV Inlet Line and #Pieces PSV Outlet Line. The pieces mentioned is enlargement and contraction, i.e expanders and reducers. You have thereby the possibility to add a number of expanders and reducers on one single inlet line and one single outlet line.

 

Corresponding to these two columns there are two rows; "To diameter (In line) and To diameter (Out line). But it does not make sense to have an entry in the intersection between the "#Pieces PSV inlet Line" and "To Diameter (Out line)",  because you are either in the inlet line or the outlet line. Not simultanously both places ! I have proposed to Aspentech to grey out those cells, it should not be possible to enter any number there.

 

Again, the line sizing feature is both confusing and have limited value. I overcome the problem with calculating the inlet line "3% pressure drop" by utilizing the Pipe segment possibility with its fittings database. You are welcome to take contact with me if you want a closer look. Alternatively, probably you can use Aspen Hydraulics.