Create a new flowsheet

Select the Add () icon in the top right corner of the Flowsheet Models page.

If your refinery consists of several linked towers, or includes process units which can be modelled as towers, these must be added separately to the topology and can be modelled separately.

1. Enter details

Use the Overview page to enter a name, description and other basic configuration information for a flowsheet.

If you wish to share the completed flowsheet with other Assay users, select the share you wish to publish the flowsheet to from the Share dropdown menu.

The flowsheet will then be available for use by other users with access to this share, but they will not be able to edit the flowsheet topology.

Details

The Details page is used to set the overall details for the flowsheet. Set the appropriate Temperature Unit by choosing the unit from the drop-down list.

2. Set up the schematic

The Schematics page allows you to define the layout of the units in the flowsheet.

Click on units in the Toolbox pane to add them to your flowsheet. To connect units, hover the mouse pointer over the end of a pipe until it is highlighted, then click and drag the pipe to connect it to the inlet of a unit.

Edit the name and other properties (such as the number of inputs and outputs on a unit) in the Properties pane. All units and their pipes can be renamed to make your flowsheet easy to understand.

3. Add unit modes

The Unit Modes page allows you to configure the cut points and fractionation indices for your distillation columns.

For each distillation tower in the flowsheet, you must enter at least one set of cut points and SI factors. These can be calculated using other tools. You can also create additional sets of fractionation parameters for towers that can be run in multiple modes. To add a mode to a tower, click the Add Unit Mode icon and supply the required details.

You can rename a unit mode by double clicking on the mode name in the table. This allows more meaningful names to be assigned to each mode than the default New Unit Mode 1 format, which can make selecting the correct mode easier at later points in the workflow.

If you have multiple distillation towers in the flowsheet, define unit modes for each one in turn by selecting it from the menu in the top left corner of the page.

4. Add global modes

The Global Modes page allows you to configure running modes for the flowsheet as a whole, by creating sets of unit modes. To configure a global mode, select a unit mode for each distillation tower in the flowsheet. Distillation units can also be disabled if a mode requires it.

Like unit modes, global modes can be renamed by double-clicking on the mode name in the table header.

5. Group units

The Grouped Units page allows you to organize units into groups. A set of groups can be defined for each global mode defined for the spreadsheet. Once groups have been defined, each unit in the spreadsheet can be assigned to a group.

Once you have finished working on your flowsheet, save it by clicking the Save icon in the top right corner of the page.

The Diagnostics page will provide warnings and errors for the flowsheet configuration.