Assay Lightends Data

The Assay Lightends Data window is used to directly supply the rates for components which are defined in the problem component list. Lightend components are considered to be an integral part of the assay stream and their normal boiling points are used to define the front portion of the TBP distillation curve, superseding the data from the assay laboratory distillation.

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 the Stream Assay Definition Window. Finally, push the Lightends button to display this window and supply the lightends data.

From the Assay Lightends Data Window, select the desired Composition Basis option for the light ends: Moles, Weight, Liquid Volume, or Gas Volume. Liquid volume and Gas volume correspond to the standard liquid and gas volume units selected for the problem.

Select the desired Specification of Total Lightends Flowrate. The available options are:

Match to TBP Curve

The lightends total flowrate is adjusted such that the normal boiling point of the mid percent for the highest boiling lightend component exactly matches the TBP curve. The lightend components are kept in the same ratio as the supplied composition. This option is the default.

Fraction of Assay

This defines the total lightends as a fraction of the total stream fluid flowrate. The lightends total may be expressed as either the liquid volume or weight fraction of the total assay stream by selecting the desired option from the Basis drop-down list box. The default basis is the basis used to supply the distillation curve.

Percent of Assay

This defines the total lightends as a fraction of the total stream fluid flowrate. The lightends total may be expressed as either the liquid volume or weight percent of the total assay stream by selecting the desired option from the Basis drop-down list box. The default basis is the basis used to supply the distillation curve.

When fraction or percent option is selected, the Normalize Component Flowrates... option may be checked to designate that the supplied composition is normalized to the supplied total flowrate. An error is signaled when the supplied composition does not sum to either 1.0 or 100.0, within a tolerance of 1%, and the Normalize option is not selected.

Use Compositions as Actual Rates

The composition entries are used as the actual component flows and the total lightends flowrate is equal to the sum of the individual flowrates as shown by the Total field at the bottom of the table.

Lightends Rate

This defines the total lightends rate. The appropriate units and basis can be selected using the Unit-of-Measure Window, which is displayed when the UOM button the Toolbar is pushed. The Normalize Component Flowrates... option becomes available and may be checked to designate that the supplied composition is normalized to the supplied light ends flowrate. An error is signaled when the Normalize option is not selected and the individual compositions do not sum to the specified lightends rate, 1.0, or 100.0, within a tolerance of 1%.

After the Specification of Total Lightends Flowrate option is chosen, enter the compositions for all the lightend components in the composition table. Lightends components may be library components, and/or petroleum components that are present in the problem component list. A running total of the composition is displayed as the data is supplied. The necessary basis or rate units may be selected through the Unit-Of-Measure Selection Window by pushing the UOM button on the toolbar.

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