Appearance
Building a Flowsheet on the Canvas
How to lay out process units and streams in the simulation editor, move them around, and save your work.
Where: the simulation editor, at /simulation/editor. You get there by opening a plant template from the simulation library, by opening a saved simulation from Simulations, or by compiling one from a drawing.
What you see
The canvas shows your flowsheet: one box per process unit, coloured by what it is, with its type icon in the middle and its name underneath.
| Colour | Kind of unit |
|---|---|
| Green | Influent / source |
| Grey | Effluent / discharge / sink |
| Light blue | Clarifier / settler |
| Light cyan | Bioreactor — CSTR, PFR, MLE, SBR, aeration |
| Light brown | Digester |
| Light yellow | Pumps, blowers, valves |
| White | Anything else |
Streams are drawn as arrows between the units, running out of one unit's right-hand side and into the next unit's left-hand side. They turn in right angles rather than cutting diagonally across the sheet, and a recycle line — return sludge, internal nitrate recycle — loops underneath the units it connects instead of running back through them.
Stream colour follows what is in the pipe: blue for liquid, orange for gas, brown for sludge, magenta for a chemical dose.
The small dots on each unit's left and right edges are its inlet and outlet ports. They are what you drag from to connect two units.
Adding a unit
- Find the unit you want in the Process Units panel on the left. The panel is grouped by treatment stage, and you can search it.
- Click it. The cursor becomes a crosshair and a hint appears at the top of the canvas telling you what you are about to place.
- Click the canvas where you want it.
The unit appears there, selected, with its properties in the right-hand panel.
If you change your mind between the two clicks, press Esc or click Cancel in the hint.
Tip: Place a unit roughly where it belongs in the process train, left to right. Streams are drawn from a unit's right side to the next unit's left side, so a left-to-right layout reads the way a P&ID does.
Moving a unit
Drag it. The unit follows your pointer while you hold the button and lands when you let go. Its streams re-route as you go, bending and looping the way they will once you drop it — what you see during the drag is what you get.
Ctrl/⌘ + Z puts it back.
Connecting two units
Every unit has two small dots on its sides: an outlet on the right and an inlet on the left. Drag from one unit's outlet to another unit's inlet and let go — that draws a stream between them.
You do not have to hit the dot exactly. Releasing anywhere on the other unit's box connects to the port that completes the line. You can also work backwards: start on a unit's inlet and drag to the one upstream of it; the stream still runs the right way round.
The line you are dragging turns red when the place you are pointing at will not be accepted, so you can see the answer before you let go. Press Esc to abandon the stream.
Three things are refused, with the reason shown in the bottom-left corner of the canvas until you dismiss it:
| If you try to… | You will see |
|---|---|
| Connect a unit to itself | A stream cannot start and end on the same unit. |
| Join two outlets (or two inlets) | Connect an outlet to an inlet — that end is another outlet. |
| Repeat a connection that already exists | These two units are already connected by a stream. |
The return line between an already-connected pair is fine — a return-sludge line from the clarifier back to the anoxic zone is a different stream, not a repeat.
New streams start with no flow set. Open the stream's properties to give it one, or let a run compute it.
Tip: The port dots disappear when you zoom a long way out. Zoom back in past about 40 % and they come back.
Getting around the canvas
| To… | Do this |
|---|---|
| Zoom in or out | Scroll the wheel — the canvas zooms around whatever is under your pointer |
| Zoom from the keyboard | + and - |
| Pan | Hold space and drag, or drag with the middle mouse button |
| Fit the whole flowsheet on screen | The Fit button in the bottom-right corner, or press 0 |
The zoom percentage is shown next to those buttons. A flowsheet is fitted to the canvas automatically the first time it loads, so you start with the whole thing in view.
Plain dragging on empty canvas draws a selection box, which is why panning needs space or the middle button.
Selecting
- Click a unit to select it and see its properties on the right.
- Shift-click (or
⌘-click) to add units to the selection, or take one out. - Drag on empty canvas to draw a box around several units at once.
- Click empty canvas to clear the selection.
- Double-click a unit to open its quick-edit dialog.
A selected unit is outlined in the accent colour. Press Delete or Backspace to remove everything selected — one undo brings the whole batch back.
Saving
Save sits in the toolbar next to the model name. It lights up as soon as you change anything — adding a unit, moving one, editing influent data, configuring a controller — and greys out again once your work is on disk, with the time of the last save beside it. Ctrl/⌘ + S does the same.
If the button is greyed out, there is genuinely nothing to save; hover it and it will tell you so.
Note: Saving stores more than the picture. Your influent data, COD and TKN fractionations, controllers and chosen output variables all travel with it, so they are still there when you come back.
Scenarios
A scenario is a saved set of operating conditions you can compare against others — see Scenarios.
A newly opened template has a flowsheet but no scenario yet, and a small prompt at the top of the canvas offers to create one. It is only a prompt: your flowsheet stays visible and editable, and you can ignore it until you actually want to compare cases.
Which project does this belong to?
Every simulation belongs to a project. When you open a plant template from the library, the new simulation is filed under a project straight away — the one you came from if you opened the template from inside a project, otherwise the project you worked in most recently. You can see and change it on the Simulations page.
If your account has no projects at all yet, the editor will say so and ask you to create one first.
Related
- Steady-State Simulation — running the flowsheet you have built
- Adding Controllers to a Flowsheet
- Simulation editor canvas — the technical reference for how the canvas is built