Excel library for process calc's including distillation

[carlo.stenali]

>I have a question about HEM and HNE models for PSV sizing/rating,
>do these models work for non-critical flows ?
>(I mean a flow where the maximum speed is below critical flow)
>It may seem a stupid question but I have to size some PSV with
>Pset = 5 Bar.a and Pdischarge (flare network, dynamic) = 2 Bar.a

when PSV outlet pressure > Pin / 2
flow can become subcritical, the method ISPF() in Prode Properties gives reasonable results also in this are within certain limits,
you may find a discussion in this blog entry

'http://www.egpet.net/vb/entries/82303-PSV-sizing-with-HEM-%28Homogeneous-Equilibrium-Model%29-limits-of-application'

[cstaff]

thanks Carlo,
very useful comment !
I have found a note about using the Constant Volume Flash operation of Prode Properties for estimating the initial condition in the vessel when PSV opens,
could you provide some details?

>when PSV outlet pressure > Pin / 2
>flow can become subcritical, the method ISPF() in Prode Properties gives reasonable results also in this are within certain limits,
>you may find a discussion in this blog entry
>
>'http://www.egpet.net/vb/entries/82303-PSV-sizing-with-HEM-%28Homogeneous-Equilibrium-Model%29-limits-of-application'

[cstaff]

thanks Carlo,
very useful comment !
I have found a note about using the Constant Volume Flash operation for estimating the initial condition in the vessel when PSV opens,
could you provide some details?

>when PSV outlet pressure > Pin / 2
>flow can become subcritical, the method ISPF() in Prode Properties gives reasonable results also in this are within certain limits,
>you may find a discussion in this blog entry
.....

[davidbottassi]

Thank you very much!
Very useful!!!!

[carlo.stenali]

>I have found a note about using the Constant Volume Flash operation for estimating the initial >condition in the vessel when PSV opens,
>could you provide some details?

you can calculate the fluid temperature and phase equilibria with a flash operation where you specify the volume and pressure,
see this blog entry

'http://www.egpet.net/vb/entries/82307-Calculate-fluid-temperature-and-phase-equilibria-when-a-PSV-opens'

[cstaff]

thanks Carlo,
the procedure for calculating the conditions when the pressure safety valve (PSV) begins to discharge is useful to decide whether a specific depressurization system is required,
that is a important point as per API requirements,
does the procedure for simulating the depressurization system in Pro de Properties allow to specify the heat absorbed / exchanged by vessel ?

[carlo.stenali]

cstaff,
yes, the procedure to simulate the vessel depressurization in Prode Properties allows to specify the heat exchanged as well other details as mass etc.
I will provide a short description in a new post.

[tmander]

the procedure for vessel depressurization in Pr ode Properties calculates both fire case and blow down with specified amount of heat exchanged (i.e. with air)

[matrenel]

I have a old version,
however, as said by others, the procedure appears to be capable to simulate both PSV and BDV operations.

[cstaff]

thanks all,
I wish to simulate a fire case (Blowdown) with Prode Properties,
actually we do this with a different software which is *very* expensive,
hence our interest for this specific application.

[tmander]

I see the point :-))
actually we use Prode Properties in both small and large projects,
Prode resides in our company server so that data is available to everyone working on a project,
we have developed std. forms and procedures (in Excel) and Office.

[Rzlisk]

It's useful one. Thank you