The impact of increasing the liquid level in the lower column on distillation operations
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As the title suggests, with the improvement in the liquid level control at the bottom of the tower, what impact does this have on oxygen purity and the argon fraction?
Precise temperature and pressure control have an impact on the distillation tower. By the liquid coming out of the tower, do you mean the liquid level at the bottom of the tower? This design already uses floating values. In production, it is possible to try adjusting the temperature or pressure to modify the operation of the distillation tower, for example by changing it by 0.5 degrees Celsius.
First, understand the principle and function of the liquid level setting for the tower. The function of the liquid level in the lower column is to act as a liquid seal, preventing gas from entering the liquid-air phase and reaching the upper column. If it loses its function, it will cause distillation abnormalities. Originally, liquid air products were to be extracted; if gas is extracted instead, it will affect the amount of steam rising in the tower, as well as the reflux flow rate to the tower. Therefore, the control lower limit for the level of the liquid in the tower must not prevent gas from being extracted, while the upper limit must not affect the intake of air. Stable control within this range is necessary to ensure stable runoff.
The liquid-air level in the lower tower serves primarily as a buffer and a liquid seal; it only needs to be kept at a certain height above the outlet of the liquid-air pipe, as long as it does not overflow into the air inlet of the lower tower. Manufacturers usually provide controls to maintain this level within a specific range. There is essentially no need to adjust the liquid-air level while the system is in operation; if adjustment is indeed necessary, it is recommended to make multiple small adjustments instead~~
Increasing the liquid level affects the reflux ratio of the upper layer; once it stabilizes, there is no impact.
The liquid level in the lower tower has little overall impact on the operating conditions, provided it remains stable.
What are the specific impacts? (Design range: 15–40%) For example, if I change the liquid level control from 20% to 30%, what effects will this have on the temperature, pressure, purity, etc., under distillation conditions?
Under normal operating conditions, increasing the liquid level in the lower column is achieved at the expense of reducing the liquid flow rate in the upper column. During this period, the amount of liquid flowing upward and downward in the tower decreases. It depends on the rate at which changes take place: if the changes are made slowly, the impact should not be significant. However, if there is an attempt to raise the liquid level quickly, it will inevitably lead to a sudden stop in the reflux flow going upward. You can think about the rest of this issue slowly.
The oxygen purity will temporarily increase while the argon residue will decrease
The adjustment is based on making small adjustments multiple times, without affecting the coating reflux~~