Use this command to display the Phase Envelope data entry window. This is a simplification of the Phase Envelope Unit Operation.
Stream Name field - Since only one stream at a time can be analyzed by this hot key, the Stream ID is defaulted in the Stream Name entry box.
Description Field - The "Description" is optional, but if supplied should appear as a heading in the report of tabular data, or on a generated plot.
Curve Declaration block - This is a set of 5 lines that allow the user to declare a minimum of one and a maximum of 5 liquid fraction curves.
Initially, only the first curve is "active". The Liquid Mole Fraction field contains the text "Full Envelope" and is not available to be altered by the user. Pressing the "1" button to the immediate left of this field toggles the field inactive (i.e., "grayed out) or active (white background).
When this curve is active, it generates a complete phase envelope including the complete bubble and Window curves.
Additionally, the critical point, cricondenbar (i.e., maximum pressure), and cricondentherm (maximum temperature) are marked on this curve on a plot. Those same points are included and identified in the tabular report, if any.
Any of 4 other possible curves (2 through 5) may be toggled active or inactive by pressing the corresponding number button immediately left of the Liquid Mole Fraction field. When active, the Liquid Mole Fraction field requires a numeric value between 0.0 and 1.0 inclusive. A mole fraction of 1.0 implies a bubble point curve. Any intermediate value may be entered. A blank entry is invalid in an active field. An active field with a blank entry is bordered in red.
The remaining curves (2 through 5) are optional. Initially, all of them are inactive; i.e., they are "grayed out".
Each of them may be toggled on or off (i.e., active or inactive) by clicking their respective number buttons (immediately left of the liquid mole fraction field). The Liquid Mole Fraction field of an inactive curve should be "grayed out".
There are no "Cut", "insert", or "Reset" buttons. This differs from the Phase Envelope Unit Operation. Only the 5 curves are available, and any one button may be made inactive.
The Thermodynamic System box - This initially displays the default thermodynamic method.
Note: Only SRK and PR thermodynamic methods are valid in the Phase Envelope. Other fields may be available but empty. This behavior is identical to that of the Phase Envelope Unit Operation. If the thermodynamic method of the target stream is valid, it is used.
Show Plot button - Pressing the Show Plot button calls the phase envelope calculation module and immediately displays the results of all the declared curves on a single plot. There are no user-controlled plot options. Settings are as follows:
There is a single plot with temperature on the X axis and Pressure on the Y axis.
All declared curves appear on the single "comparison" plot. There is no optional "individual" plot.
Inactive curves; i.e., curves that are "grayed out", are not generated or displayed.
Show Table button - Pressing the Show Table button calls the phase envelope calculation module and immediately displays the numerical results of all the declared curves in tabular form. The format of the tabular data should be consistent with the tabular report from the Phase Envelope Unit Operation. Inactive curves; i.e., curves that are "grayed out", are not generated or displayed.
The Cancel button closes the window and returns the focus to the main PRO/II window, typically the PFD. All data in the WINDOW is obliterated and lost.
NOTE: Both tabular and plot reports are supported in this unit operation. In particular, the plots are supported through the PROVISION GUI on the "Output à Generate Plot" menu.
The Phase Envelope is fully supported in the PROVISION Graphical User Interface (GUI).