The pound sign # is used to reference tool variables in the same way that the at sign @ is used for fluids and the dollar sign $ is used for variables.
For the tower tool, stage variables are reference by immediately follow the #name with dot stage number, follow by a dot and either a variable designation or a phase dot variable designation. In this case I am using an underscore instead of a minus sign to designate the bottom stage, since a minus sign could be confused in a formula with the arithmetic operator.
The stage variables T (temperature), P (pressure) and Q (calculated energy input) do not depend on the phase and so immediately follow the stage number, as in
The stage variables F (flow), X (mole fractions) and D (side draw flow) are dependent on phase and must be preceded by a dot separated phase designator of either L (liquid) or V vapour. Thus for composition we have:
The tower also supports two variables that do not depend on the stage, totalfeedf (the sum of all feed flows) and minfeedp (the lowest feed pressure). These would be referenced in the follow in manner:
Tap the Bulk button to see the properties of the tower bottoms.