Access
From the Options menu, select Stream Property lists.
Click the New button to open the New List dialog box.
In the List Name: field, enter a unique name to identify the new list. A list cannot be created without entering a unique name in this field.
The Copy List drop-down list box allows copying in an existing to get started. This often is a convenient shortcut when the new list will resemble an existing list. The default None option does not import any existing lists.
Click OK to save the list name and activate the Define Stream Property List dialog window.
Constructing the List
The most common method for constructing a list is as follows:
Scroll the Select Properties list box to find a property.
Click the desired property to highlight it.
To select additional properties at the same time,
(a) Highlight a (first) property, then hold down the keyboard Shift key and left-click a second property. This selects all properties between the two clicked properties.
(b) Highlight a property, then hold down the keyboard Control key and left-click another property. Only the two clicked properties are selected. Continue scrolling and clicking while holding down the Control key to select any number of additional individual properties.
Click the Add button to copy the highlighted properties to the Property Description UOM Format field on the right. For convenience, we refer to this field as the List field
Changing Order of Appearance
The properties will appear in the final list in the order they appear in the List field. To reorder the properties:
Click to highlight one or more properties in the List field.
Hold down the Shift key or the Control key when clicking to select more than one property, as desired.
Use the Up, Down, Top, and Bottom buttons to move the selected properties to a different location.
Highlight one property in the List field and click Remove to delete the property from the list.
Click the Clear button to delete all properties from the List field. This action cannot be undone. The list will have to be reconstructed from scratch.
Changing the Appearance of a Property
To change the appearance of a property, highlight a single property in the List field. This activates the Description and Format fields below the List field. If the property represents a floating-point value, this also activates the UOM radio buttons.
Edit the text in the Description field to change the display text in the final list.
Edit the Format field to change the display of the value. The format codes follow C/C++ language conventions, and may be tricky when one is not familiar with those programming languages. PRO/II applies default formatting to all entries that is acceptable in most circumstances.
When the UOM buttons are active, they allow changing the units of measure used to report the value. The first button converts, labels, and displays the value using dimensional units used during simulation input. The second button converts, labels, and displays the value in the dimensional units used in the final output report. Output units often are the same as input units. The third button allows selecting a specific UOM from the appropriate dimensional class, regardless of the units used for input or output.
Using the Search Tools
The Search Properties for selection field is an alternative method of locating desired properties in the Select Properties list. To use it;
Type some text to find in the Search Properties for selection field. Only alpha-numeric characters type into the Search Properties for selection field. Also, the percent symbol serves as a "wild card" character.
Text in the Search Properties for selection field also activates the Match, Phase, and Basis controls. Use those controls to customize the search criteria.
Click the Search button to display all the available properties that match the search criteria.
Delete all text from the Search Properties for selection field to restore the full property list in the Select Properties field.
Explanation of Terms that Appear in Property Descriptions
Property descriptions intend to be self-evident while being concise. To this end, they use jargon and some abbreviations that are in common use by chemical engineers. Non-chemical engineers who utilize the product may be confused by these technical terms. The following is intended to remove as much ambiguity as possible without exhaustively discussing each individual property.
Operating conditions represent the actual conditions at which the stream participates in a simulation. Sometimes these also referred to as "hot, flowing" conditions. At any given composition, the temperature and pressure of the flowing stream define all degrees of freedom for phase state and therefore uniquely determine other properties such as enthalpy. Take for example, the description "Vapor pressure @ Operating conditions = Boiling Point Pressure at stream T". This intends to mean that the reported vapor pressure was calculated using the composition and temperature of the stream. However, instead of using the actual stream pressure, the stream was flashed to determine the maximum pressure that would allow the stream to vaporize. This effectively indicates the stream is at "saturated liquid" conditions. Any increase in temperature, or any decrease in pressure would cause the liquid to begin to vaporize. So, the reported value in this description is the vapor pressure of the saturated liquid.
Standard or Std. The property is reported at standard conditions rather that at the actual operating conditions of the stream. Various organizations have defined a number of datum bases that each use a specific temperature and pressure to define the standard conditions. PRO/II allows user to adjust the standard conditions as desired.
Liquid or Liq., Vapor or Vap., or Solid These indicate the reported property was computed for indicated phase only, and not for the bulk stream as a whole.
Total basis indicates the reported property is an attribute of the entire stream, inclusive of all phases. This contrasts to vapor-phase only or liquid phase only properties.
Critical properties are values taken at the upper limiting conditions above which the component cannot form either a liquid or solid phase. Tc, Pc, Zc typically represent temperature, pressure and compressibility at critical conditions.
Reduced properties are dimensionless representations of property values as a fraction of critical properties. For example, assume the critical temperature of a component is 390 Rankine, and the component is in a stream at a temperature of 292.5 Rankine. The actual flowing temperature is 292.5R and the reduced temperature Tr = 0.75 = 292.5R / 390.0R. Tr, Pr, Zr typically represent reduced temperature, reduced pressure and reduced compressibility.
Kay's Rule Many bulk stream properties are computed from contributions of the individual components in the stream. For example, the critical temperature of a stream often is computed as the sum of the individual component critical temperatures. Kay's rule is a basic concept that scales the contribution of each constituent based upon it's relative abundance in the mixture being considered. A tacit implication is that the same amount of any constituent at the same conditions contributes the same as any other constituent. Usually for stream calculations, the constituents are individual components and their relative abundance is their mole or weight fraction. With these preliminaries stipulated, Kays rule may be simply stated as
Vtot = SUM( Vi * Xi )
where Vtot is the total bulk property value, Vi is the property value for pure component i, and Xi is the fraction of component i present in the stream.
For example, the description "Critical Pressure = Total Crit. Pressure (Kay's Rule)" indicates the reported critical pressure was calculated for the total stream (including all vapor and liquid phases) using the Kay's rule methodology. Completely analogous logic applies to other similar property descriptions; such as "Critical Temperature = Total Crit. Temperature (Kay’s Rule)".
Mole or M, Weight or WT or mass, Volume or LV or GV basis These qualifiers appear most often in descriptions of properties computed using Kay's rule. They describe the basis used for the "Xi" terms. A mole of a component consists of Avogadros's number (about 6.023x1023) molecules. Molecular weight is the weight of one mole measured in one gravity of force. Mole volume is the volume of a mole of the component in the form of an ideal gas measured at standard temperature and pressure. A distinction is made between liquid volume (LV) and gas volume (GV) because the volume of a liquid and a gas at standard conditions are so different. Note that for any specific component in a mixture the values for mole fraction, weight fraction, and volume fraction usually are different. This results in different values for a bulk property computed using Kay's rule, depending upon the basis used for the Xi terms.
Total, Dissolved, and Free or Decant Water Free water is considered pure and forms a separate liquid phase from other components in a stream. For non-rigorous thermodynamics in particular, free water may be decanted (drawn off separately). Dissolved water is the water that mixes with other components, even after the free water is drawn off. Total water includes all the free and dissolved water. Properties may be computed using any of these bases.
Wet or Dry or Water Free Properties When all the water present in a stream is included in a property calculation, the property is said to be on a Wet basis. When all water is excluded from the calculations, the property is said to be a Dry property. When using non-rigorous thermodynamics, decant water removes all water, including any dissolved water. When using rigorous thermodynamics that predict a separate water phase, dissolved water remains in the non-water liquid phase. The term Water Free applies in either situation to properties that exclude the water phase from the calculations.
Stream Property Table - General Information
Stream Property Table Main Window