Swing cuts

If you wish to have swing cuts in your report, select the Enable swing cuts check box at the top of the tab. By default, the swing cuts available in the template are automatically configured based on the information you previously supplied about sequential cuts.

You can modify the swing cuts between each of the cuts present in the template. The fields displayed in each row are described in the following table.

Clicking on any empty cell in a cut row allows you to type a new value into it. For each cut, you may alter the tag and name of the cut, its width, and its activity status. You may also alter the temperature unit in which the ECP and width of the cuts are measured.

To change the temperature units of the specified ECPs or swing cut widths, double click on either the ECP or Width column header. Choose between C, F, K and R from the temperature unit drop down box. When asked if you like to convert the entered values to the new unit, press Yes to convert your entered vapour temperatures to the new temperature unit, or No to leave them as is.

Swing cut analysis

The swing cut analysis tool allows you to check how closely the swing cuts in your model approximate the true values of certain properties for the affected cuts.

Being a linear approximation, swing cuts can be inaccurate in certain situations. A typical case is when swing ranges are too wide relative to cut size, especially if the distillation profile varies considerably across the range.

Click the icon in the bottom left corner of the dialog to show the swing cut analysis report in the right-hand pane. You must have selected a crude from the crude field for the report to appear.

Note The icon appears only when you are editing a template based on a flowsheet. It is not available for templates based on perfect systems.

Choose the property to inspect from the Properties drop-down at the top of the pane. The properties available in the list are those defined in the Properties tab of the template editor. See Properties.

Note Properties blending by index are not yet supported by the swing cut analysis tool.

From the Type drop-down menu, choose either of these visualization options:

• Pipes in single row: Every row shows graphs related to a cut. You may see one or two graphs in a row, according to whether one or both ends of the cut are allowed to vary.

• Swings in single row: Every row shows graphs related to a swing cut. There are always two graphs in each row, showing the error variation due to moving the light and heavy end of the cut, respectively.

You can collapse and expand each row by clicking the triangle icon next to the row name.

In each graph, the horizontal axis shows the cut end temperature, while the vertical axis shows the error on the chosen property. The meaning of the lines in the graph is the following:

• The purple line shows the median of the error distribution.

• The two red solid lines show the upper and lower quartile of the error distribution, enclosing roughly half of the error probability.

• The two black dashed lines show the minimum and maximum recorded error values.

  Tip Click the Export button at the top of the pane to create an Excel version of the swing cuts analysis report.