Thermodynamics Main Window

This window is used to define the property calculation systems for the simulation, i.e., the sets of methods used to calculate equilibrium K-values, enthalpies, entropies, densities, transport and special properties. Before running the simulation, the user is required to visit this window and select the systems used for the calculation of the above properties.

See Application Guidelines in PRO/II Reference Manual for some hints on selecting appropriate thermodynamic systems for different applications.

Usage

From the Main Window menu bar, select the Thermodynamics option under Input menu. Alternatively, you may push the $image\PFD06.gif$ button on the Toolbar.

Select (highlight) the desired category of property calculation systems in the Category list box. See Thermodynamic Property Calculation Categories for more information on the categories.

Unless the selection is Electrolyte, the systems within the category selected appear in the Primary Method drop down list box. Select (highlight) the desired system in the Primary Method drop down list box. If Electrolyte is selected, you must first select the Electrolyte System and then the required Electrolyte Model from the drop down list boxes.

Double clicking automatically transfers the selected system to the Defined Systems list box. Single clicking activates the Add button which may then be used to add the system to the Defined Systems for the simulation. See Adding Thermodynamic Methods for further details. See Additional Information below for more discussion on Primary Methods.

The Liquid-Liquid Options Window automatically appears when thermodynamic systems which support liquid-liquid calculations (VLLE) as well as a single liquid phase (VLE) calculations are added to the Defined Systems.

Several actions are available for systems that have been added to the Defined Systems. To perform these actions, highlight the system in the Defined Systems list box and push the appropriate button: Modify, Delete, Duplicate or Rename. See Actions for Selected Property Calculation Systems for further details.

Global Thermodynamic Reset Option

Select the Global Thermodynamic reset basis to transfer the thermodynamic systems between any unit operation (except Simsci Thermodynamic reset unit) and its connecting streams when they having different thermodynamic systems. You can override this global reset basis for an individual stream with Simsci Thermodynamic Reset unit operation. All the streams in the flowsheet with thermodynamic reset changes to yellow color when the simulation is run. Following are the Global Thermodynamic Reset Options:

Automatic
When upstream unit operation is in single phase, flash the upstream with constant temperature with downstream thermodynamic. If resulted stream is in same phase continue with constant temperature flash for thermodynamic reset. If resulted stream phase changed use ‘Constant Degrees Over/Under Saturation or Constant Vapor’ basis for thermodynamic reset.
In all other cases use ‘Constant Degrees Over/Under Saturation or Constant Vapor’ basis for thermodynamic reset.
Constant Temperature
Constant Enthalpy
Constant Degrees Over/Under Saturation or Constant Vapor
Dew Point
Bubble Point
Constant Enthalpy – Do not Reflash
Select this option to match the simulation results with pre-v10.1 results.

Note: “Automatic” is the default option for newly created simulations. “Constant Enthalpy – Do not Reflash” is default for run batch & import of .inps and migration of .przs to v10.1 and later.

Import Component and Thermodynamic data

If there is no Components and Thermodynamic data in the current simulation, you can extract it by importing an inp or prz file in the simulation. Assay Cutpoint and Characterization can be extracted only when the current simulation Assay data is in the default state. Reaction Sets and Reaction Procedures can be extracted only when there are no Reaction Sets and Reaction Procedures in the current simulation. Similarly, UOM data can be extracted only if the Input and Output UOM data is in the default state (not customized by the user). Global Thermodynamic Reset option can also be extracted with this option.

For extracting Component and Thermodynamic data for all new problems, select the default simulation file (inp or prz) from the Global default options.

The Component and Thermodynamic data can be successfully extracted from an input file only when the input file does not have any import errors.

Assay and Spiral components cannot be extracted from the inp and prz files.

If there are more than two thermo systems, reaction sets, or reaction procedures, you can open the Select Required Thermodynamic Systems, Reaction Sets & Reaction Procedures window by clicking Extract. The window is divided into three different sections, one each for thermo, reaction, and procedure data. Also, corresponding check boxes are provided for each of them. Select the required data sets by selecting the respective check boxes. By default, all sets are selected.

Additional Information

Selection of a system in the Primary Method drop down list box is a convenient means to define a complete system of thermodynamic methods for the calculations. Each name in this list box is the Equilibrium K-value method for a complete system of thermodynamic methods. Other methods, as appropriate, are combined with the Equilibrium K-value method to define the system. The Thermodynamic System - Modification Window may be used to change any of the methods which are provided with a system.

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