Streams
A stream is the arrow that connects two unit operations on the canvas. It carries a material flow, and the solver determines its temperature, pressure, flow rate and phase compositions from the units on either side of it.
You create a stream by dragging from the connector dot on one unit to the connector dot on another, as described in How to build a process. A stream has no specifications of its own beyond its label. Everything it carries follows from the units it connects.
Heat is transferred differently. A heat flow connects a red source handle to a blue sink handle and carries a duty rather than a material flow.
Streams that start and end a flowsheet
Three unit operations exist only to begin or end a stream:
- Input stream: The feed entering the flowsheet. This is where temperature, pressure, flow rate and composition are specified.
- Product stream: The final outlet of a branch. It needs no configuration, and simply collects whatever the connected stream delivers.
- Cycle stream: Closes a cycle that has no external feed. You give initial guesses for temperature, pressure and flow rate, and the solver updates them until the cycle is consistent.
For a loop whose fluid does originate from an Input stream, use a Recycle instead of a Cycle stream.
Fluid package and composition
The process fluid package sets the equation of state and the components a stream is allowed to contain. The composition says how much of each component there is, and is specified on the feed-like units, meaning Input stream, Cycle stream and Recycle.
One fluid package can therefore serve several feeds with different compositions. Use the Composition Manager to edit all of them in one table.
Where properties are shown
Double-click a stream to open its details panel, which has three tabs:
- Results: The solved properties of the stream, listed per phase along with the phase compositions.
- Safety Checks: Whether unwanted phases such as ice, dry ice, hydrates or free water are stable in this stream. See Global Safety Scan.
- Validation: What is still missing or inconsistent before the process can be solved.
To compare every stream at once, press Results in the process editor and open the Streams tab. That table can be filtered, configured by column, and downloaded as CSV. See Results & Analysis.