Solving Mass Balances on a Distillation Column
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This Demonstration shows the solution of mass balances around a distillation column. One or two feeds enter the column and a distillate stream leaves the top while a bottoms stream leaves the bottom of the column. The unknown variables are in blue; use sliders to select the correct values, then check "solution." Click the "new problem" button for a new problem. The three options correspond to a binary feed in a single feed stream, a two-component system with two feed streams, and a ternary feed in a single feed stream. For the binary systems, the mole fractions for component 1 are given (, ). For the ternary system, the mole fractions of components 1 and 2 are given.
Contributed by: Rachael L. Baumann (June 2018)
Additional contributions by: John L. Falconer and Neil Hendren
(University of Colorado Boulder, Department of Chemical and Biological Engineering)
Open content licensed under CC BY-NC-SA
For the option "two unknowns," a binary mixture is fed to a distillation column. Two of the six variables (, and are the feed, distillate and bottoms flow rates (kmol/h), and , and are the feed, distillate and bottoms mass fractions of component 1) are unknown, and their values are obtained from these mass balances:
For the option "two feeds," a binary mixture is fed to a distillation column in two streams ( and are the two-feed flow rates, and and are the two-feed mole fractions for component 1), and the two unknowns are obtained from the mass balances:
For the option "three unknowns," a ternary mixture is fed to a distillation column in one feed stream. The mass fractions of components 1 and 2 are either given or to be solved for. The three unknowns are obtained from these mass balances: