How to Troubleshoot Distillation Issues

Distillation is a laboratory separation technique that uses differences in boiling points of various components in a liquid mixture as the basis for separation. Selective evaporation and condensation techniques are then employed to purify this solution into (near) pure components – an extremely popular separation technique employed within organic chemistry.

Temperature measurements in laboratory distillation apparatuses must be placed strategically to allow vapor from various components to rise to an area where it can condense and collect. If the thermometer is not placed here, vapor cools off, decreasing temperature readings on the thermometer – something which doesn’t directly impact distillate quality but does hinder chemical analysis by collecting an accurate reading on boiling point temperature of liquid being distilled.

Mechanical issues can pose challenges for distillation columns. Vibrations may cause mechanisms to shift over time and damage parts of the column internals resulting in decreased separation efficiency and loss.

Distillation columns often experience excess entrainment or maldistribution of vapor. This issue usually stems from improper design or installation of distributors; weir-trough or orifice pan distributors without taps to allow liquid bypass between beds are one such common error that contributes to this issue.

Idealized models of distillation systems follow Raoult’s law and Dalton’s laws of partial pressures, which assume vapor-liquid equilibrium can be reached. Unfortunately, however, reality differs drastically and controlling distillation processes at industrial scale can be very challenging to control. Distillation troubleshooting is possible, however; this article compiles decades worth of hands-on experiences for troubleshooting distilations operations into an easily accessible reference for anyone involved in operating, designing, studying, improving, or managing large-scale distillation operations.