Distillation is a separation process, which uses the different volatilities of the components in the mixture to separate the components. Commonly used equipment are plate distillation column and packed distillation column. The principle and equipment flow of precision distillation are the same as those of ordinary distillation, but the relative volatility between components in the system to be separated is small (
Isomers usually coexist in natural essential oil, which is the raw material for producing isolated spices. For example, citronellol and rosanol coexisting in natural essential oils such as geranium oil, rose oil and rose grass oil are optical isomers. The boiling point difference of these isomers is relatively small, so it is difficult to achieve effective separation of this kind of separated perfume by general distillation process, so precision distillation is widely used in the production of separated perfume.
Classification of distillation column plates
1. According to the tray structure, there are bubble plates, sieve plates, valve plates, mesh plates and tongue plates. The bubble-cap tower and sieve-plate tower were the earliest used in history, and the valve tray was developed around the 1950s. At present, sieve plates and float valve trays are widely used, and other different types of trays are also used. Some new trays or improvements of traditional trays are also being developed and studied.
2. According to the gas-liquid two-phase flow mode, there are cross-flow trays and counter-flow trays, or downcomer trays and downcomer-free trays. Tray with downcomer is widely used, with high mass transfer efficiency and wide operation range; Countercurrent tray without downcomer is also often called cross-flow tray, and both gas phase and liquid phase pass through small holes on the tray. The tray is simple in structure, and the whole tray area is fully utilized.
3. According to the type of liquid flow, there are single manifold, double manifold, U-shaped manifold and other manifolds (such as four manifold, stepped manifold, circular manifold, etc.). ).
Refer to the above content: Baidu Encyclopedia-Distillation