When the air separation tower is making argon, how much argon fraction can be extracted? What are the restrictions on it?

Argon fraction is separated from oxygen and argon in the crude argon tower. Argon fraction enters from the bottom, and the top gets crude argon containing about 95% argon. Because the boiling points of oxygen and argon are close, it is difficult to separate, and about two thirds of argon is washed down. At the same time, argon fraction enters from the bottom, and the liquid at the bottom contains high argon, then it goes back to the main tower to take part in the rectification. Therefore, only part of argon in argon distillation is extracted as crude argon product, and the required argon distillation component is about 35 ~ 40 times.
When extracting crude argon from the whole low-pressure air separation plant, due to the tension of cold volume, too much expansion volume will have a negative effect on the rectification of the upper tower, so the extraction volume of argon distillation should not be too large, about 8% of the processed air volume ~ 15%. Therefore, the extraction rate of argon is relatively low, the highest is only 30% ~ 35%. For high and medium pressure units, the cooling capacity is relatively rich, and increasing the expansion capacity does not affect the rectification, so the extraction capacity of argon fraction can reach 25% ~ 28% processing air volume, the extraction rate of argon can reach 60% at most. The extraction rate of argon from molecular sieve purification pressurized whole low pressure air separation plant can reach up to 87%.