First 2-day course for distillation design (CHEMCAD) online

Finally a first again. I had long time planned to prepare this course to explain graphical pre-computer methods and link them to rigorous calculation results from a simulator.

I think, it went quite nice and I am looking for repeating it hopefully many times in the next years:


The course covers the design of binary and multicomponent distillation mostly based on the book “Distillation Design” by Henry Z. Kister.

The McCabe-Thiele method is shortly reviewed and applied to identify the optimum feed location, different types of pinches and the effect of cooling and heating on column stages, effect of more than 1 feed, sidedraws, ….

McCabe-Thiele Plots are usually constructed after applying certain simplifications. After a short introduction into Excel-VBA, a short macro is developed to generate the plot based on the results of a rigorous simulation.

In case of multicomponent distillation of non-ideal mixtures, design boundaries (minimum number of stages, minimum reflux ratio) are difficult to determine, as simple short-cut methods (Underwood, Gilliland, Fenske) are useful only for relatively ideal mixtures.

To visualize the operating conditions and identify correct feed location, reflux ratio, …, graphical methods based on the results of multicomponent rigorous column simulations are introduced and discussed (Hengstebeck-, Key Ratio- and d/b-Plots).

An Excel macro (VBA source code) program is provided as part of the course material, that can generate these diagrams automatically from the column profile output in CHEMCAD.

The diagrams allow to easily identify mis located feed points, wrong thermal state of the feed, excessive reflux or reboil and and allow to identify cases, where additional feeds or side-draws or intermediate heat exchangers are attractive.

A short outlook is given on similar methods for extraction (Hunter-Nash) and combined balance line construction in extraction-distillation combinations (example: QVF-process for acetic acid recovery (De Dierich)).

Agenda 1st day  

9:00 – 11:00


Modelling of VLE and VLLE in a nutshell

Azeotropic behaviour and infinite dilution activity coefficients

Distillation modelling via the equilibrium stage approach

Single and multiple stage equipment, different configurations

Stripping and rectifying, mass balance and McCabe-Thiele (binary)

11:00 – 11:30


11:30 – 13:30

Workshop: McCabe-Thiele from simulation result profile

Short introduction to Excel-VBA

Workshop: McCabe-Thiele VBA-macro

Optimum feed stage and pinching, cure pinching

Minimum reflux ratio and tangent pinch

Complex columns (> 1  feed, intermediate cooling or heating)

Agenda 2nd day   

9:00 – 10:30

Multicomponent columns and key components

Component lumping

Interpreting composition and temperature profiles

Hengstebeck-, key-ratio- and d/b-plots from simulation result profile 


Pinching in multicomponent columns

Retrograde distillation

Optimum feed location

10:30 – 11:00


11:00 – 12:30

Workshop: Hengstebeck-, key-ratio- and d/b-plots in Excel

Column profile in ternary diagrams, distillation and residual curves, distillation fields. Balance lines and mixing points.

Application examples

Final discussion, open questions

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