Assay Main Window (Input Menu)

For many petroleum based stocks the composition is not completely known in terms of defined components. Therefore, the stock must be characterized with TBP boiling point ranges or pseudocomponents for which the necessary thermophysical data have been estimated before solution of the problem is possible.

PRO/II has numerous techniques for converting petroleum assay data into pseudocomponents. These procedures are discussed in Assay Curves - Technical Information.

The input of petroleum assay data is divided into two functional parts:

1. Definition of blend cutpoints and characterization methods for the current problem via this window.

2. Assignment of blend cutpoints, flowrate, and thermal condition to petroleum stream assay data from a library set to define a stream in the current problem. See Stream Data Window for more details.

Note that the first step is not necessary when the primary set of cutpoints and default characterization options supplied by PRO/II are satisfactory for all petroleum streams in the problem. Note that the second step is always necessary for any problem which uses the assay procedures.

Usage

From the "Input" menu of the Main Window, select the Assay Characterization command. For easier access you can also click the button on the Toolbar in the Main Window. Both options display the main Assay DEW shown here.

The Primary Cutpoint Set

The Primary TBP cutpoint set is always supplied by PRO/II. See Primary Set Defaults for the cutpoints supplied with this set.

• Press the Modify Primary Set ... button to change the cutpoint ranges of the Primary Set. See Modifying the Assay Primary Cutpoint Set for further details.

• Push the Define New Cutpoint Set button to supplement the primary set with one or more secondary cutpoint sets. See Defining/ Modifying Assay Secondary Cutpoint Sets for further details.

Secondary Cutpoint Sets

After being added, secondary cutpoint sets appear in the Defined Secondary Sets: list box. To perform actions on a secondary set.

• Select (highlight) a secondary cutpoint set in the list box. This also activates the following action buttons.

Modify : Opens the Assay Data - Secondary Set of TBP Cuts data entry window. The set may be modified as desired.

Delete : The set highlighted in the list box is removed from the simulation.

Changing the Default Cutpoint Set

When one or more secondary sets have been added to the simulation, the Default Cutpoint Set: drop-down list box becomes available. The default cutpoint set applies to assay streams that do not specify the cutpoint set in the stream data. Initially, the Primary set is the default.

• Highlight any set in the list box to designate it as the default set.

See Default Assay Cutpoint Set for more information.

Modifying Characterization Methods

Each simulation supports a single set of assay characterization methods that applies to all cutpoint sets. It is not possible to declare different methods for individual cutpoint sets.

• Push the Characterization Options button to open the Assay Data - Characterization Options dialog.

• Select the characterization methods desired for the simulation.

See Assay Characterization Options for further details.

Action for Spiral Lightends

Till PRO/II v10.0, only 16 components were considered as Lightends from SPIRAL crude, but from PRO/II v10.1, 59 components are considered as Lightends. User is provided with option either to choose old list of Lightends or extended list of Lightends. The list of components supported as Lightends are given in table at this location.

See Supported Lightends for Spiral Crude Sets for more information