Processes and Balances
Separation Processes
13 min · 2 worked examplesFree
Getting the product out of the mixture, which is usually most of the plant and most of the energy.
After this lesson you can
- Explain what distillation exploits
- Match a separation method to the difference available
- Say why separation usually costs more than the reaction
Distillation
Distillation separates liquids by boiling point. Heat the mixture and the vapour is richer in the more volatile component; condense it and you have separated a little.
A single stage rarely separates enough, so a column stacks many stages vertically. Vapour rises and liquid falls, contacting at each tray, and each contact improves the separation slightly. More trays means a purer product.
Reflux, returning some of the condensed overhead product to the top of the column, is what makes high purity possible, and it is expensive: everything refluxed must be boiled again.
Distillation is reckoned to account for a large share of all industrial separation energy, which is a direct consequence of the latent heat figure from the energy balance lesson.
In the full lesson
- Distillation
- Other separations
- Why separation dominates the cost
Free with an account. Read it, work the examples, answer the questions, then build it in the simulator.