Prode Properties

Properties of pure fluids and mixtures, multi phase equilibria, process simulation, software

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Distillation

Distillation is a separation process widely applied in chemical industry, it can provide a good method for separating a mixture of volatile components except for a few cases such as when the components have similar boiling points...

The separation is achieved by the contact between the rising vapors and the liquid flowing down inside the column. The vapor leaving a stage is richer than the feed in the more volatile components while the liquid leaving a stage is richer than the feed in the less-volatile components. To promote the contact between vapor and liquid flows the columns contain devices which may be grouped into two general categories : Tray-type and Packing-type. In general, one can solve a distillation column by considering the overall system :

Rigorous methods describe columns as a group of equations, for steady state operations these are the so called MESH equations :

- Material balance equations
- Equilibrium equations
- Summation equations (with different constraints)
- Heat balance equations

There are several rigorous computational methods for solving these sets of equations, Prode Properties adopts different procedures based on quasi-Newton or Newton solvers which are selected according the problem to solve.

Solve a distillation column with Microsoft Excel

With Prode Properties you can solve staged columns with one or more feeds and one or more side streams, this Excel application example shows how to specify inputs and print in Excel a detailed table with results

Load the predefined Excel page, specify the problem and get the results

From Excel menu File->open , in Excel folder (in Prode Properties installation) select the file column.xls

The predefined page allows to define and solve different kind of columns, distillation columns with reboiler and condenser, absorbers etc. with one or more feeds and one or more side streams...

The steps to define a column are easy to follow :

- define the number of stages
- define pressure distribution (button and top stage)
- define stage efficiency
- define the number of feeds, each feed flow rate and compositions (click on the proper Feed button to access the stream editor), each feed stage (remember that reboiler (if present) is stage 1 and condenser (if present) is stage N, and the liquid fraction per each feed (good practices suggest to adopt a value near 1)
- Define the number of side streams (if any) , the stage, the type (vapor or liquid flow) and the flow specification
- Define variables as condenser and reboiler and the related specifications, the procedure allows different specifications including the molar fraction of a component in top or bottom stage

To edit / modify a feed just click on the related feed's button to access the stream's editor

Once the column has been defined it is suggested to verify the input data specifically for inconsistent specifications, if you are sure that all is Ok run the solver (button Solve Column)

The procedure prints a detailed report which includes :

- the verified errors in mass and energy balance
- reboiler and condenser duties
- temperature and pressure in each stage
- total and component vapor flows in each stage
- total and component liquid flows in each stage

Prode Properties, technical features overview

- Comprehensive set of thermodynamic models, the different versions include
- Models based on liquid activity
- Predictive models (UNIFAC etc.)
- Cubic EOS
- Soave-Redlich-Kwong standard and Prode extension
- Peng Robinson standard and Prode extension
- Prode extended versions with parameters calculated for best fitting of vapor pressure, density, enthalpy, specific heats...
- van der Waals and complex mixing rules to combine equations of state with activity models
- Huron Vidal
- Wong Sandler ( WS )
- Michelsen ( MHV2 )
- Tassios et al. ( LCVM )

- Association contribute

- Models for electrolyte solutions
- SAFT (with association)
- Benedict Webb Rubin, Lee-Kesler (Plocker) ...
- GERG (2008) / AGA 2017
- Steam Tables IAPWS 95
- ...

Typical applications

- Fluid properties in Excel, OpenOffice, Python and Windows, Linux, Android
- Thermodynamics, physical, thermophysical properties
- Process simulation
- Heat / Material Balance
- Process Control
- Process Optimization
- Equipments Design
- Separations
- Instruments Design
- Realtime applications
- petroleum refining, natural gas, hydrocarbon, chemical, petrochemical, pharmaceutical, air conditioning, energy, mechanical industry