Stream Assay Definition
This window is used to provide the petroleum stream assay data. Assay data include laboratory distillations, average gravity or Watson K-factor, and, optionally, gravity curves, light ends breakdown, and molecular weight curves. The minimum assay data which must be provided are a laboratory distillation and the stream average gravity or Watson K-factor. The assay data are used to characterize the stream with lightends components (defined) and petroleum pseudocomponents over its entire boiling range. See Assay Curves - Technical Information for further details on the characterization procedures.
Usage
From the Stream Data Window, select the Petroleum Assay option and push the Flowrate and Assay button to display the Petroleum Assay Stream Window. From this window, push the Define/Edit Assay button to display this window.
Select one of the Distillation types and, optionally, the Basis (liquid volume or weight) for the distillation curve. The pressure for the distillation should also be entered for distillations at pressures other than 760 mm Hg. For ASTM D86 distillations only, the temperatures may be corrected for cracking using an API Data Book method by checking the correct for cracking option. See Assay Distillation Types for more information on laboratory distillations.
Use the table to enter the laboratory distillation data by supplying the cutpoint (expressed as a percentage of the cumulative distillates) and the temperature of the cut. The fitting procedure selected in the Assay Characterization Options Window is then used to process this data. For additional information on entry of distillation data see Assay Distillation Curve.
Select the type of Gravity Data to be supplied. The stream average value must be supplied. Optionally, a gravity curve may be supplied by pushing the Gravity Curve button. See Assay Gravity Data for additional details.
Optionally, Molecular Weight or Lightends data for the stream may be supplied by pushing the appropriate button. See Molecular Weight Data and Lightends Data windows for more details.
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