Degree-of-Freedom Analysis on a Distillation Process

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In this Demonstration, a degree-of-freedom analysis
is performed on a distillation process to determine whether the system has
sufficient information to solve for the unknown variables. Use buttons to select
the unit on which to do mass balances (distillation column, condenser, or
reboiler) or to do a balance on the overall system. When "condenser" is
selected, use buttons to select "partial condenser" or "total condenser". Set
the "total number of unknowns" with the slider; unknown variables are colored
blue on the diagram and known variables are black. The known variables are
selected randomly, and they change when you click the "new problem" button.
Use buttons to select how species B is represented: as z_{B} or as 1 -
z_{A}; the degree-of-freedom analysis is different for each
representation. An explanation of the analysis is shown on the right. For zero
degrees of freedom, the balances are solvable. The system is overspecified if it
has more equations than unknowns and it is underspecified if it has more unknowns
than equations. For a reboiler, the equilibrium ratio K_{r}, is known,
and for a partial condenser the equilibrium ratio K_{c} is known.
Temperatures and pressures are known for this analysis. Mass balances and phase
equilibrium relations are solved to determine the unknown variables.

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available for free from the Wolfram website.
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