The volume fraction of argon in the air is 0.932%, and its boiling point is between oxygen and nitrogen. When it enters the lower tower and rises one by one along the tower plate, argon and oxygen are more volatile than nitrogen, and they condense into the liquid tank more than nitrogen. Generally, the concentration of argon in the gas tank should be gradually reduced. However, because the oxygen content in the air is much larger than that of argon, and the oxygen is a volatile component compared with argon, therefore, oxygen condenses more into the liquid tank than argon, so on the first few towers, the concentration of argon in the gas tank increases relatively. However, with the large amount of oxygen condensation, the oxygen content in the gas tank decreases, and the argon condensation increases relatively gradually. Therefore, the argon content in the gas tank gradually decreases, reaching only 0% points after the tower top. Since nitrogen in liquid air still accounts for about 60%, most argon condenses in liquid air. Generally speaking, the argon content in the lower tower liquid is 1.3% ~ 1.6%, the content of argon in liquid nitrogen is only about 0% points.
There are two argon-rich zones on the top and bottom of the liquid-air inlet respectively. The reason is that argon contains 1.3% ~ When 1.6% of the liquid level flows down from the inlet of the liquid level, rising vapour will be encountered on the tower plate, and part of the liquid will be evaporated. Among them, nitrogen, the volatile component, evaporates more into the gas tank than oxygen and argon, so the concentration of oxygen and argon in the liquid tank increases gradually. However, after a certain number of tower plates, the nitrogen in the liquid tank basically evaporates, and the remaining part is only the components of oxygen and argon. The liquid goes downwards, which is actually the separation of oxygen and argon. Because argon is volatile to oxygen, argon evaporates much more than oxygen in the downstream process, so the content of argon in liquid gradually decreases, in this way, the argon-rich area below the liquid inlet is formed.
Both the rising steam in the distillation section and the steam after the liquid-air throttling contain a certain amount of argon. When the steam meets the downstream cold liquid during the rising process, part of the steam will condense into liquid. Among them, the volatile components oxygen and argon are more condensed into the liquid tank than nitrogen, so the content of argon in the gas tank should have been gradually reduced, but because the content of oxygen in the gas tank is higher than that of argon, moreover, oxygen is a volatile component for argon, so oxygen condenses more into the liquid tank than argon, so the concentration of argon in the first few towers is relatively increased. With the large amount of condensation of oxygen, the condensation of argon increases relatively, and the content of argon in the gas box gradually decreases. In this way, the argon-rich area above the liquid inlet is formed.
The distribution of argon in the upper tower changes with the change of oxygen, nitrogen products and concentration. When the output of oxygen decreases, the purity of oxygen will increase. At this time, the argon-rich area will move up, that is, the argon content in the argon-rich area of the distillation section will increase, however, the argon content in the argon-rich area of the distillation section is reduced. This is because the total content of oxygen, argon and nitrogen in the gas tank on the same plate should be 100%, and the total content of oxygen, argon and nitrogen in the liquid tank should also be 100%. If the purity of the product's oxygen increases, that is to say, the oxygen concentration of the gas tank and the liquid tank on the tower plate of the distillation section increases, while the sum of oxygen, argon and nitrogen is 100%, so the content of argon and nitrogen is bound to decrease. And because the argon content in the air is certain, the argon content in the distillation section decreases, and the argon content in the distillation section is bound to increase correspondingly. If the output of nitrogen decreases, the concentration of nitrogen will increase, and then the argon-rich section will move down. That is to say, the argon content in the argon-rich area of the distillation section should be reduced, and the argon content in the argon-rich area of the distillation section should be increased.
