Stream Mixing Methods

The stream mixing methods determine how the stream property value is calculated from the individual component values. The options are:

Summation: The stream property value is determined by summing the product of the component property value and the component fraction. The fraction may be molar, weight or liquid volume and is calculated from the total stream dry composition except for kinematic viscosity when it is from the dry liquid part of the stream. Any Index data supplied for the property will be converted to property values before the summation using the equation:

Index: The stream property index is determined by summing the product of the component property index and the component fraction. The fraction may be molar, weight or liquid volume and is calculated from the total stream dry composition except for kinematic viscosity when it is from the dry liquid part of the stream. Before the summation, any supplied property values will be converted to index values using the equation:

This equation is then used to convert the stream index value to the stream property value.

User-Formula: The stream property value is determined from the equation in a user-added subroutine which is linked into PRO/II. The user must write Fortran code for the calculation in subroutine SPUSER.FOR in the UASLB library. Refer the the User-Added Subroutine User Guide for more information. Data values may be entered for each component and up to 20 real and integer data values may also be supplied.

User-Index: The stream property value is determined by a user-added subroutine which is linked into PRO/II. The user must write Fortran code for the calculation in subroutine CVUSER.FOR in the UASLB library. Refer the the User-Added Subroutine User Guide for more information. The USINDEX options requires that DATA or INDEX values, or the NCFILL option be provided for the property.

SimSci: This method is only available for cloud point and kinematic viscosity. It is an index method but uses specific index equations.

API, API99, API07, etc.: API procedures may be used to calculate flash point, cetane index, mean average boiling point, cubic average boiling point, mole-average boiling point, volume-average boiling point, weight-average boiling point, net heating value, and a variety of other so-called refinery inspection properties. API methods typically require no component data. The API option indicates the base version of the procedure, typically from the 1984 (or earlier) API Data Book. The exact version may be different for each refinery property. API99 indicates the procedure as defined in the 1999 API Data Book, and API07 indicates the procedure as defined in the 2007 API Data book. Other similarly dated API key words exist for versions of procedures published in other years. The Thermodynamic Input Data Manual lists all methods currently available in PRO/II.

Nelson: This is an alternative correlation to calculate flash point and no component data are required.