Distillation: Principles and Process

• Distillation is a separation process by heating a liquid to its boiling point, transferring the vapor, condensing it, and collecting the condensate.
• It separates liquid mixtures with different boiling points and purifies liquids.

Operation Principle

• Distillation separates liquids with different boiling temperatures by heating them.
• The more volatile liquid evaporates first and passes into a condensing column to revert to liquid.
• Further heating evaporates and distills the less volatile liquids at higher temperatures.
• Simple and fractional distillation are the two main types of distillation.

Pure Liquid Distillation

• A pure liquid maintains a constant boiling point when liquid and vapor are in equilibrium.
• In simple distillation, the vapor pressure increases and expands until it reaches the water-cooled condenser.
• The vapor condenses and passes down the condenser into the receiver.

Water Distiller Parts

• Vapour generator (boiling tank): container for water to be distilled
• Water level: regulates water quantity inside the vapour generator
• Control valve: controls water flow to the vapour generator tank
• Hydraulic connection: network supplying water in liquid phase to the vapour generator tank
• Water in liquid phase: water inside the vapour generator tank that receives thermal energy and converts to vapour
• Immersion resistors: generate heat via electrical current
• Refrigeration water outlet: line condensing water vapour by removing thermal energy
• Condenser: cools vapour and returns it to liquid
• Filter: activated carbon filters removing flavors or particles at the condenser/collector exit
• Distilled water container: collects the distilled fluid in special plastic to avoid ionic contamination

Distillation Types

Simple Distillation

• The setup includes a boiling flask, an adapter with a thermometer, a condenser with cold water, and a collection flask.

Fractional Distillation

• Similar to simple distillation, but with a fractionating column between flask and condenser.
• The fractionating column, filled with glass or plastic beads, improves liquid separation.
• The beads provide "theoretical plates" for the refluxing liquid to condense, re-evaporate, and condense again.
• More volatile liquids move to the top, while less volatile liquids stay at the bottom.
• More theoretical plates require more energy and time.

Simple vs Fractional Distillation

Simple Distillation

• Simpler setup and faster distillation with less energy consumption.
• Suited for liquids with large boiling point differences (>70°C) or solid impurities
• Gives poorer separation, works well with relatively pure liquids

Fractional Distillation

• More complex setup and longer distillation time with more energy consumption.
• Suited for complex mixtures with smaller boiling point separations and better separation.