The liquid air separation plant includes the lower tower, upper tower, condensing evaporator, argon system, main heat exchanger, subcooler, liquefier and is placed in a separate cold box. After distillation in the lower tower, high purity nitrogen is obtained at the top of the lower tower, which is reheated by the main heat exchanger and then exits the cold box and goes to the nitrogen circulation system to recover the cold from the liquid air separation plant to make liquid nitrogen. The lower tower also gets dirty liquid nitrogen, lean liquid air and oxygen-rich liquid air in turn, which then goes to the upper tower after being sub-cooled by the cooler to participate in the upper tower distillation. The middle of the upper tower to obtain argon fraction through the argon tower distillation to obtain high purity liquid argon, the bottom of the upper tower (condensing evaporator)to obtain high purity liquid oxygen.
The air compression dawdling cooling system, including the air compressor and heat exchanger to the high temperature section of liquid air separation plant not recovered by the nitrogen circulation system of the cold, through the appropriate refrigerant, such as glycol aqueous solution, further recovery, and then go to the air compressor intercooler and final stage cooler to cool the compressed air to about 5 ℃.
For nitrogen circulation systems, liquid air separation plant is available in a wide range of pressures from 0.2 to 10.0Mpa. The methane does not leak into the air separation system and is safe. The whole air separation system, through the lower tower pumping dirty liquid nitrogen, poor liquid air so that the air separation device does not reduce the extraction rate due to the liquefaction of part of the raw material air.
