Gravity Curve Generation Methods
When a gravity curve is not provided for an assay stream, the gravities for the pseudo-components must be generated using one of the techniques described below. These options are supported in keywords using the GRAVITY entry on the ASSAY statement.
Constant Watson K from TBP Curve (WATSONK)
A Watson K Factor is estimated for the stream, based on its TBP and the supplied average gravity. The gravity for each pseudocomponent is then back-calculated from the stream average Watson K factor by using its average normal boiling point. The stream average Watson K Factor is adjusted until the blended gravity for all of the stream components equals the supplied average gravity for the stream.
Constant Watson K from ASTM Curve (PRE301)
For this method, the stream average Watson K Factor is determined by using the average of the D86 temperatures at 10, 30, 50, 70, and 90 percent and the supplied average gravity. This average K factor is next applied to each pseudocomponent at its normal boiling point to determine its gravity. The entire gravity curve is normalized as required to match the supplied average gravity.
Note: This method was used by the Simsci Process Simulation Program prior to Version 3.01 and is provided for upward compatibility.
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