AdvancedTopic 72 of 100Materials & Chemical
Distillation
Separates mixtures by differences in volatility using staged columns.
In depth
Distillation separates liquid mixtures by boiling-point differences via repeated vaporisation and condensation on trays or packing, with reflux and reboiler. Key design: number of stages, reflux ratio, feed location, column diameter. Used in refining, solvents and spirits.
Key points
- Minimum reflux and minimum stages
- Murphree tray efficiency
- Energy-intensive
ExampleA crude oil column separates naphtha, kerosene, diesel and residue at different heights.
What is Distillation?
Separates mixtures by differences in volatility using staged columns.
Why is it important to understand distillation?
Distillation separates components by their boiling points and is the most common separation in the chemical and petroleum industries.
How does a distillation column work?
Vapour rises through trays or packing while liquid flows down, and repeated contact enriches the vapour in the more volatile component.
What is reflux?
Liquid returned to the top of the column to improve separation, which increases the energy used but gives purer products.
How is Distillation used in practice?
Typical applications include separating ethanol from water to make a fuel-grade product, refining crude oil into gasoline and diesel fractions and recovering a solvent from a waste stream for reuse.
What should I learn before Distillation?
Study "Vapour-liquid equilibrium" first (topic 71 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Distillation?
Minimum reflux and minimum stages. Murphree tray efficiency. Energy-intensive.
Can you give an example of Distillation?
A crude oil column separates naphtha, kerosene, diesel and residue at different heights.
What comes after Distillation?
The next topic is "McCabe-Thiele method", which builds directly on this one.
How difficult is Distillation?
It is classed as Advanced in Materials & Chemical (topic 72 of 100). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Materials & Chemical.