Friday, May 3, 2013

Prode Properties includes a procedure to design/rate pressure safety valves with critical or two-phase flow with the most accurate models
-HEM (Homogeneous Equilibrium Model)
-HNE (Homogeneous Non-Equilibrium) with boiling delay and gas-liquid split contributes
-HNE-DS (Homogeneous Non-Equilibrium)
-NHNE (Non-Homogeneous Non-Equilibrium)
With Prode Properties you can size / rate a PSV directly in Excel (see the following application example)
typical applications are vaporizing/flashing fluids, critical, supercritical conditions,
in addition the rigorous thermodynamic models included in Prode Properties allow an accurate evaluation of all the thermophysical properties required.
The image shows a typical application in Microsoft Excel for a quick and accurate design and rating.
For additional information see

How to calculate fluid conditions inside a vessel when PSV opens

In a vessel protected by a PSV the temperature inside the vessel may reach values higher
than those allowable for vessel's materials,
for these cases a depressuring system is required.
Prode Properties allows to calculate the temperature when the PSV opens.
The basis of the procedure is the flash operation at specified volume and pressure.
In this example we will see how to utilize Microsoft Excel and Prode Properties to
calculate the fluid temperature inside a vessel when the PSV opens.
The example allows to define composition, t, p (operating conditions) and PSV discharge

The procedure calculates the temperature and phase equilibria when PSV opens.
To define the composition from Excel open Prode Editor, select stream 5 (or whichever you prefer) and define the composition.
In cells B1 and B2 enter operating pressure and temperature,
the procedure will calculate specific volume in cell B3,
in B3 set the macro =EStrV(5,$B2,$B1)
in B5 set the macro = VPF(5,$B4,$B3,0)
In cell B4 enter the discharging pressure for PSV,
the procedure will calculate the fluid temperature at specified discharging pressure.
To view compositions at specified discharging pressure open Prode Editor and select the stream

How it works ?
The procedure calculates specific volume (gas + liquid) at initial conditions,
then it solves a flash operation with specified volume and pressure
to find the temperature when PSV opens

Pin, Tin = initial conditions
Pfin = PSV discharging pressure 

For additional information