Introduction to vacuum distillation column

Vacuum distillation is a very common unit operation used in the petrochemical and pharmaceutical chemical industries. A distillation column capable of vacuum distillation operation is called a vacuum distillation column.

Vacuum distillation is a very common unit operation used in the petrochemical and pharmaceutical chemical industries. Vacuum operation can reduce the bubble point and dew point of the operating materials in the tower, and reduce the chances of some materials, especially heat-sensitive materials, chemically reacting at high temperatures to produce impurities. For example, the separation of ethylbenzene and styrene under normal pressure is easy to produce heavy tar in the tower still. Vacuum distillation can reduce impurities and improve the product purity of styrene. Another example is the vacuum distillation of crude oil, which can reduce the thermal decomposition of residual oil and improve the quality of gas oil. The reduction of the bubble point of the column still helps to choose a conventional heating method to heat the column still. At low pressure, the relative volatility of some materials will also increase, which will improve the separation effect.

Through the use of vacuum distillation column, compared with atmospheric distillation, the difference in boiling point and relative volatility of materials under different vacuum degrees can be used to improve the separation effect. Vacuum distillation technology can also be applied to the separation of azeotropes, high efficiency and energy saving.
Compared with atmospheric distillation, the disadvantage of vacuum distillation is that the investment and operating costs are larger, especially with the increase of vacuum degree, the investment cost will even increase exponentially. Through the rational design of the vacuum system at the top of the distillation column, including the selection of vacuum equipment, the design of Condenser, pressure control and piping, etc., it will help to reduce the investment and operating costs of the system, and contribute to the stable operation of the vacuum column. .
The vacuum distillation column overhead system usually consists of vacuum equipment, column overhead condenser, reflux system, etc.