Gasoline Blending Plus

BLENDIS for ASTM Distillation

     BLENDIS is an empirical model based on published data and a large amount of unpublished data.  It handles wide boiling range components, narrow boiling range components, pure hydrocarbons, and oxygenates separately and provides interaction equations on terms of percent evaporated at user-specified temperatures.  In addition, it provides predicted temperatures and temperature blending values for 10, 50 and 90% points.  Predicted Driveability and the ASTM Distillation component of the V/L calculation are also included.

     The standard interaction equation is used for pairs of wide-boiling components (90% minus 50% of 50°F or more).  For pure hydrocarbons and oxygenates, blending values are used which range from negative to above 100% evaporated  Interaction terms are not used for pure hydrocarbons and oxygenates.  Interaction equations for narrow boiling components are interpolated between appropriate pure hydrocarbons and wide-boiling components.

     Blend predictions are in terms of percent evaporated at specified temperatures because those predictions are more accurate than 10%. 50% and 90% temperature predictions.  A specification of 50% minimum at 240°F is identical to a specification of 240°F maximum at 50% evaporated.   (Reference 5)

     Input to BLENDIS is ASTM distillations of components specified, compositions and temperatures of interest.  Output is blending values and interaction equations wherein the % evaporated term differs from the measured values for narrow boiling and pure components.

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