Extraction column is an important liquid-liquid extraction equipment, and its special working process and characteristics make it widely used in many fields. The working process of the extraction column mainly includes three stages: mixing, mass transfer and separation.

First, the extractant and the liquid enter the tower from the top and bottom of the tower respectively. In the tower, the two-phase liquid is fully mixed by various internal components (such as packing, sieve plate, etc.).

In the mixing process, the solute is transferred from one phase to another phase to realize the mass transfer process. For example, in the process of extraction of acetic acid aqueous solution by butyl acetate, butyl acetate is in full contact with acetic acid aqueous solution in the tower as an extractant, and acetic acid is transferred from water phase to butyl acetate phase.

As the two-phase liquid flows through the tower, the mixture is gradually stratified. The denser phase (usually the water phase) flows down and is discharged from the bottom of the tower; A less dense phase (usually an organic phase) flows upward and exits the top of the tower.

In this process, the mass transfer process in the extraction tower is continuous, and by controlling the operating conditions in the tower (such as flow rate, temperature, etc.), efficient extraction separation can be achieved. One of the characteristics of the extraction tower is the high mass transfer efficiency.

Because the internal components in the tower can provide a large mass transfer area, the two-phase liquid is fully in contact, thus accelerating the mass transfer process of the solute. Compared with the extraction tank, the extraction tower can obtain higher extraction efficiency and reduce the amount of extractant under the same processing capacity.

Secondly, the extraction tower has the advantage of small footprint. Due to its vertical structure, the footprint of the extraction tower is much smaller than that of the extraction tank under the same processing capacity. This is of great significance for some enterprises with limited land resources.

In addition, the operation flexibility of the extraction tower is greater. It can adapt to the changes of feed composition and flow in a certain range, and still maintain a good extraction effect by adjusting the operating parameters.

In actual production, the properties and flow rate of the material may fluctuate, and this operational flexibility of the extraction tower can ensure the stability of the production process.

However, the extraction tower also has some disadvantages, such as the relatively complex equipment structure and high investment cost; It has high technical requirements and requires professional operators to maintain and manage.

The extraction column plays an important role in the field of liquid-liquid extraction because of its unique working process, high mass transfer efficiency, small footprint and large operating flexibility. Despite some shortcomings, with the continuous development of technology, the performance of the extraction tower will continue to be optimized and improved.