The reason why two-stage distillation columns are commonly used in air separation towers is mainly based on their efficient product extraction rate and ability to simultaneously produce high-purity oxygen and high-purity nitrogen. The two-stage distillation tower consists of two sections, the upper section is called the low-pressure tower (or crude distillation tower), and the lower section is called the high-pressure tower (or distillation tower).
During the working process, the mixture first enters the bottom of the high-pressure tower and begins to evaporate after heating. In the high-pressure tower, the mixture will gradually decompose into different components, among which the low boiling point components will evaporate first, rise to the top of the tower, and flow into the low-pressure tower through some means (such as a reflux channel). In the low-pressure tower, the reflux liquid is repeatedly contacted and mixed with the evaporated components to achieve better separation efficiency. The high boiling point components will condense into liquid in the low-pressure tower and sink to the bottom of the tower; And the low boiling point components will continue to rise and eventually flow out from the top of the low-pressure tower. The two-stage distillation tower can more effectively separate the components in the mixture through two distillation and condensation processes, thereby improving the extraction rate of the product.
Due to the structural design of the two-stage distillation tower, it can simultaneously produce high-purity oxygen and high-purity nitrogen in the same process, meeting the demand for high-purity gases in different industrial fields.
