Flowsheet based streams in the measurement grid

When performing laboratory analysis cuts of crude are usually sufficiently separated that the streams can be considered to be perfect cuts. Occasionally however it may be necessary to use flowsheets to define the streams in an assay rather than perfect cuts. If enough distillation data is available to build a complete flowsheet the imperfect distillation can be modelled and used to represent the streams during assay generation.

To use flowsheet based streams in the Measurement Grid:

1. Set up the Measurement Grid using perfect cuts

   The Measurement Grid is set up the same way whether entering data for perfect cuts or for flowsheet based cuts. Data should be entered using the standard methodEnter data. See Enter data.

   Assay data is entered on the Measurements page of the Document.

2. Add a new flowsheet with the same number of product streams

   A new flowsheet must be created with product streams matching the cuts in the assay. The flowsheet should be created using the Create a flowsheet..

3. Fit the flowsheet using any distillation data available

   The flowsheet parameters can be fitted using Distillation Unit Fitting within the Flowsheet Manager. As much distillation data as is available should be entered and fitted for the assay streams. If distillation data is not available for particular product streams Assay will attempt to estimate the fractionation parameters. Yield data is required for all assay streams. See Fit flowsheets.

4. Assign the new flowsheet to the assay

   

   After creating the flowsheet in the Flowsheet Manager the flowsheet must be added to the document's Flowsheet page. To add the flowsheet to the document:

   1. Open the Flowsheet page of the document by clicking its link in the Navigator.

   2. Click the Copy Flowsheet icon to open the Flowsheet Models list.

   3. Select the name of the newly created flowsheet from the list and click Select to add the flowsheet to the document.

5. Add flowsheet streams to the Streams page of the Document

   

   Before cuts in the assay can be associated with flowsheet streams the streams from the flowsheet must be added to the Streams page of the Document. To do this:

   4. Open the Streams page by clicking its link in the Document Navigator

   5. Right-click the streams list in the Streams page, and from the context menu select Add All Flowsheet Streams.

6. Associate the flowsheet streams with cuts in the Measurement Grid

   

   The flowsheet streams in the Streams page must be associated with the cuts in the Measurement Grid. To associate streams on the Streams page with streams in the Measurement Grid:

   6. Return to the Measurements Page by clicking its link in the Document Navigator.

   7. Click the arrow in the first heading of each stream column (or row).

   8. From the drop down menu select the stream associated with the particular cut in the assay.

7. Generate the assay

   Generate the assay using the flowsheet cut points and fractionation parameters to define the streams, rather than perfect cut points.