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I am preparing a basic course on Separation Processes (5th semester, BSc Chemical Engineering). I can see that many well-known textbooks (e.g. Seader & Henley, Wankat) start by teaching in detail distillation and only then, the chapters on absorption/stripping are presented. As a student, I think I was taught exactly the opposite: first absorption and then distillation, which I believe it is a natural way as absorption is significantly simpler than distillation. My question is, what are the pros and cons of teaching first absorption and then distillation?

My own list would be:

Pros

  • Absorption/stripping equilibria are often described by Henry's law (or similar). It is an easier first step than complex VLE expressions
  • It's a good way to introduce McCabe-Thiele algorithms
  • No condenser or reboiler. Therefore, no need to do energy balances at first (only when vaporization heat is very significant)

Cons

  • Distillation is the most relevant separation process and it is important to allocate a lot of time to its thorough study
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    $\begingroup$ You have a good starting point. FWIW, I take the same approach as you were taught -- absorption/stripping and then distillation -- for the definitive positive reasons that you list. Also, (Seader, Henley, Roper 3rd Ed) do absorption/stripping before distillation. Finally, in case you may be blocked out b/c this is a question for opinions rather than for conclusive answers, feel free to contact me off-line to share other insights (that I won't expand here). $\endgroup$ May 7, 2019 at 19:34
  • $\begingroup$ It is easier to teach absorption first though if you introduce the flash first absorption comes naturally $\endgroup$
    – Media
    May 14, 2019 at 22:33

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