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Prode, software solutions for process industries
Prode, software solutions for process industries


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Prode Properties allows to compare HEM (Homogeneous Equilibrium Model) against different models as HNE (Homogeneous Non-Equilibrium Model) and NHNE (Non-Homogeneous Non-Equilibrium Model),
this rigorous procedure allows to select the most suitable pressure relief valve for a specific application
for additional information
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Prode Properties includes rigorous procedures for design / rating of compression units, you can simulate single or multiple compression stages (polytropic path),
the models includes are
a) Huntigton, applicable to gas phase, based on (Maxell) dH=TdS+VdP
b ) Schultz (Asme PTC 10), applicable to gas phase, based on PV ^ n = C
c) Polytropic solution with phase equilibria, based on solution of phase equilibria along a polytropic path

the last (Polytropic solution with phase equilibria) allows to solve any problem including wet gas compression
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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)

the procedure allows to size/rate safety valves where std. procedures may suffer large errors,
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.
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Prode Properties can calculate
-vapor-liquid phase diagrams
-vapor-liquid-liquid phase diagrams
-vapor-liquid-solid phase diagrams (extended version)

the procedure shows the different equilibrium lines (vapor-liquid, vapor-liquid-liquid etc.) calculates critical points and other properties as cricondenba and cricondentherm

the image shows a vapor-liquid-liquid phase envelope for a mixture of hydrocarbons + water
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How to access Prode Properties library from MATLAB (continuation...)
In addition to the direct access previously discussed, you can use Prode Properties from Matlab with scripts or mex files.
Matlab scripts are installed in directory \Prode\MATLAB\m and before to utilize the scripts you must move the files into a Matlab directory, read Matlab documentation for additional information, then you should edit the file pppdir.txt which contains the address where the file ppp.h resides.
Scripts act as interface between Matlab and Prode Properties, scripts have names identical to Prode Properties methods, then when you invoke the script StrGD (which is the method in Prode Properties to calculate density of vapor phase) MATLAB simply executes the commands found in the file, calls the method StrGD in Prode Properties and return the result.
The file called StrGD.m contains these MATLAB commands

function [] = StrGD(stream)
if not(libisloaded('ppp'))
fid = fopen('pppdir.txt'); hfile = fgetl(fid); fclose(fid);
loadlibrary('ppp.dll', hfile);
h = uimenu('Label','Properties');
h1 = uimenu(h,'Label','Edit Properties','Callback','edSS');
h2 = uimenu(h,'Label','Open Archive','Callback','AOpen');
h3 = uimenu(h,'Label','Save a Archive','Callback','ASave');
d = calllib('ppp', 'StrGD', stream)

By typing in Matlab the command


Matlab executes the code within the script, it loads the ppp.dll (if not in memory) , creates a menu bar (with the standard Prode Properties commands) and then executes the method StrGD, to calculate the density.
You can write scripts to solve more complex problems, an example is the script phaseenvelope.m which prints a phase envelope, to test the scipt type in Matlab the command


Matlab will invoke Prode Properties to calculate the phase envelope for the stream 1 , then it plots the resulting graph (see the photo).
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Accessing Prode Properties library from MATLAB
MATLAB provides two ways to access external, shared libraries.
The first way is through the command-line interface, this interface lets you load an external library into MATLAB memory and access functions in the library, to load Prode Properties in MATLAB enter

>if not(libisloaded('ppp'))
hfile = ['C:\Program Files\Prode\MATLAB\ppp.h'];
loadlibrary('ppp.dll', hfile);
libfunctions ppp

this command will load Prode Properties in memory and print the list of methods avaliable, you may wish to modify ‘C:\Program Files\Prode\MATLAB\ppp.h' to reflect your installation’s settings...
To access a method in Prode Properties MATLAB provides the command calllib to call functions in Prode Properties library, the syntax for calllib is:

calllib('ppp', 'FunctionName', arg1, ..., argN)

the FunctionName and arguments are detailed in Prode Properties manual, for example we can call the method edSS() to edit streams with the command

>calllib('ppp', 'edSS')

n the same way you can utilize the methods in Prode Properties, for example to calculate cp / cv and speed of sound for vapor fraction of stream 1 at 300 K and 5 Bar


ans = 1.3211


ans = 374.1625

you can call complex functions as those to plot a phase envelope or calculate a column, however remember before to pass an array from Matlab to Prode Properties Library that you must allocate the memory to avoid system errors.
Finally do not forget to use the unloadlibrary function to unload Prode Properties library from mATLAB memory and free up memory.

>unloadlibrary ppp

the second way is through Matlab mex files,
this will be discussed in a next post...
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Prode Industrial Interface includes a OPC server, a OPC client, a MODBUS master and a MODBUS slave, allowing direct connections with almost all industrial devices including DCS, PLC, inline devices etc.
Given composition and/or operating conditions this Soft Sensor can estimate (with rigorous models) accurately about 40 different properties including

Critical pressure
Critical temperature
CricondenBar pressure
CricondenBar temperaure
CricondenTherm pressure
CricondenTherm temperature
Liquid Fraction
Dew point temperature
Bubble point temperature
Gas heating value
Joule Thomson coefficient
Gas Wobbe index
Gas specific entropy
Gas specific enthalpy
Gas specific heat (cp)
Gas specific heat (cv)
Gas speed of sound
Gas compressibility
Gas specific gravity
Gas compressibility
Gas specific gravity
Gas density
Gas viscosity
Gas thermal conductivity
Liquid specific entropy
Liquid specific enthalpy
Liquid specific heat (cp)
Liquid specific heat (cv)
Liquid speed of sound
Liquid viscosity
Liquid thermal conductivity
Liquid surface tension

it can provide a useful solution when hardware sensors are unavailable or unsuitable...
For additional information :
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Prode Properties can calculate multiple points for a specified liquid or vapor fraction, this permits to solve problems which cannot be solved witrh different software,
consider a simple binary mixture Methane 0.999 n-Butane 0.001
this mixture shows up to three equilibrium points at a specified temperature and liquid or vapor fraction, in the phase envelope the dew point line is red, bubble point line is black while the blue line represents a liquid fraction = 0.001, at 190 K there are up to three equilibrium points,
with Prode Properties you can easily calculate the required points with the method


where the first value (1) is the stream which we defined, the second (t) represents the temperature, the third (0) is the phase fraction (with 0 we specify 0% liquid or a point on dew line, the same would be by setting the state as gas and phase fraction as 1.0) the fourth (1) is the state (in Properties 0 = gas, 1 = liquid, 2 = solid) and the last is the required position.
For this specific mixture (see the phase envelope) we require to calculate the three equilibrium pressures points at 190 K and the results are

P(1) 14.482681 Bar.a
P(2) 37.107538 Bar.a
P(3) 43.501362 Bar.a

easy to do in Excel, Matlab or your own software !
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With Prode Properties PXY and TXY diagrams are easily created in Excel !
In this example the mixture C5H12 (nPentane) C2H6O (ethanol) at a temperature of 420 K shows a minimum at 0.65 (molar fraction) of nPentane
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A free "student's" version of Prode Properties is available for non commercial use here :

please contact Prode for a commercial version which includes more than 1500 components and 23000 BIPs, extended versions are also avalilable with additional models and options.
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