Vacuum distillation separates mixture components under reduced or high pressure. When vacuum distillation occurs at a lower boiling point, compounds are separated from higher boiling point compounds mixtures. In order to get the desired valuable products separated and recovered, vacuum distillation is necessary in several industries including:
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Vacuum distillation is performed under atmospheric conditions or vacuum. Distillation processes occur when liquid has a solid component or when liquid is a mixture of two components with different boiling points. There are two types of distillation: fractional and atmospheric.
The boiling point of a mixture during fractional distillation of a liquid is similar and cannot be separated by simple distillation; therefore, making fractional distillation a complex process.
Atmospheric distillation happens when the product is heated and distilled under atmospheric conditions. In this process lots of heating energy is required. It is important to not degrade the quality or properties of the product needing distilled.
The vacuum distillation column is typically large, with column diameter up to 46 ft. (14 m), heights up to 164 ft. (50 m) and feed rates to approximately 160,000 barrels a day.
Vacuum distillation columns must provide good vapor-liquid contact while maintaining a low pressure increase from the top of the column to the bottom. Therefore, vacuum columns utilize distillation trays only when withdrawing products from the side of the column. Most of the column uses packing material for the vapor-liquid-contact because such packaging has a lower pressure drop than distillation trays. Packaging material can be structured sheet metal or randomly dumped packing like Raschig rings.
The absolute pressure of 10 to 40 mmHg in the column is most often achieved by using multiple stages of steam jet ejectors, or a combination of steam ejectors and liquid ring vacuum pumps
The Vectra vacuum pump series is the best single stage liquid ring pump in the world. This vacuum pump series is used for differential pressure as it pulls vacuum and achieves up to 1551 mmHg discharge pressure.