Vapor Pressure Parameters Are Unknown Option

It is quite common when modeling a process in SuperPro, to require the introduction of a component that does not have a record of physical properties in any of the databases that SuperPro Designer offers as sources (System DB / User DB / DIPPR or PPDS). The behavior of this components perhaps can be approximated by another known component (e.g., Water) which can be used as a source for all (or most) of the physical properties. Typically users would change the normal boiling point of the newly created component to a new value to match the new component’s NBP (even approximately), and possibly its molecular weight (in case mol concentrations or mol fractions were ever chosen for the display of concentrations or compositions on streams or equipment contents with that component present). However, changing the NBP while leaving the previous set of vapor pressure parameters (Antoine coefficients) would create an inconsistency since now using the vapor pressure estimation expression, for 1 atm, the boiling point predicted would be that of the original (source) component and not the new NBP set for our new component. Often, components encountered in the Food or Biotechnology domain such Biomass, Solids, Fats, Lipids, Wood, etc., would not have vapor pressure data recorded in the open literature. Furthermore, in a typical simulation, such a component may never have to use its vapor pressure as it would never be set as ‘emitted’ or be part of any rigorous VLE calculations. In older releases of SuperPro Designer, the user was forced to specify all the properties of a component (incl. Antoine coefficients) when that component was registered in the flowsheet (or created in the User DB). Starting with version 11, the user can explicitly declare that the vapor pressure estimation parameters of component are unknown. Checking this option will have the following effects:

a)  The component cannot be checked as emitted in the Venting/Emissions Tabs of operations.

b)  The component cannot be checked as VOC in the Pure Component: Pollutant Categories tab.

c)   The component’s shortcut vapor/liquid criterion cannot be “Vapor Pressure (Antoine)”.

d)  If the component participates in any rigorous physical property calculation models, it is excluded from VLE calculations.

Note that even though you can declare the vapor pressure parameters as unknown, you must still provide some approximation to a gaseous Cp(T) and a heat of vaporization as a function of temperature. If you don’t have such estimation parameters for your component, you can ‘borrow’ the estimation parameters of another component that may behave somewhat similarly with yours. You can click on this button:   (Search for a Component with Similar Props...) and SuperPro will present you with an interface that will allow you to search and find a component with a similar Normal Boiling Point amongst the components already registered in your model, or present in any of your available component databases. For more details, see Search for a Component with Similar NBP... Dialog

All the above restrictions will be applied automatically as soon the user exits the Pure Component Properties Dialog. If you don’t have reliable estimation parameters for ideal gas Cp(T) and/or heat of vaporization, then you may want to declare this component as “All Vapor Parameters Are Unknown/Irrelevant” (see next).