Connecting Streams

Connecting / Reconnecting Streams

If you are new to PRO/II, or are looking for an overview on how to set up a simulation, see Process Simulation Using PRO/II's GUI.

Adding or Connecting Units with Streams

$image\EDIT03.gif$ Push the Stream button at the top of the PFD Palette to its "down" state. All outlet ports on the units in the flowsheet are displayed. Ports which are yet to be satisfied are colored red, whereas the ports which are valid but satisfied are colored green.

$image\EDIT03.gif$ Click the left mouse button at the point of origin for the stream, either a unit exit port (product) or a vacant location on the draw area for an external feed (source) stream. At this moment all the inlet ports on the units in the flowsheet are visible.

$image\EDIT03.gif$ Move the cursor to the desired terminus of the stream and click the left mouse button. The terminus for the stream can be a unit input port (feed) or a vacant portion of the draw area for a flowsheet exit (sink) stream.

Revising Stream Connections

$image\EDIT03.gif$ Place the cursor at the origin or the terminus of the desired stream, and depress the left mouse button.

$image\EDIT03.gif$ Drag the end of the stream to the desired location and release the mouse button to complete the revised connection.

Note: The origin of the stream can be connected only to a product port, whereas the terminus of the stream can be connected only to a feed port of a unit operation.

Stream Connections Involving Excluded Unit Operations

PRO/II allows a User Defined Sequence that excludes unit operations from flowsheet calculations. (Refer to Calculation Sequence Dialog.)

Unit operations in the Excluded Unit(s) list are not removed from the PFD display. Instead, the icons for their feed and product streams are "grayed out". (i.e., The display color of the stream is subdued, typically light gray on white.) For the sake of discussion, it is convenient to refer to such streams as "excluded streams".

An "excluded stream" still may be required for the flowsheet to solve. Typically, this occurs when the product of an excluded unit feeds an Available Unit. The flowsheet cannot solve if the excluded stream is undefined. However, if the user supplied an initial estimate for it, or if the database contains values from a previous run, then the excluded stream acts as an external feed to the flowsheet.

It is a simple matter to switch unit operations back and forth between Included and Excluded states.

$image\EDIT03.gif$ Right click on a unit operation icon to display its menu. Either an Include Unit or an Exclude Unit entry appears in the menu. Clicking this entry toggles the unit between the two states.

Note: Some stream connections may change as unit operations are toggled. Selectively excluding unit operations effectively alters the topology of the flowsheet. Excluding unit operations may alter the performance of the flowsheet, result in a different solution, and in some instances may prevent reaching a solution.

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