Uneven bubbling of sieve tray tower

What are the functions and classification of the rectifying column of air separation equipment?

Another part of the nitrogen vaporized in the liquefier is heated up to a certain temperature in the high pressure heat exchanger and pumped out to the low pressure nitrogen press, the nitrogen separated by the gas-liquid separator is also heated up by the high pressure heat exchanger and then goes to the low pressure nitrogen press, compressed to a certain pressure by the low pressure nitrogen press and then back to the high pressure heat exchanger for heat exchange with liquid air separat...