How to extract neon and helium from the air?

The process of extracting neon and helium from the air separation plant is divided into three steps: the first step is to produce crude neon and helium; the second step is to produce pure neon and helium mixture; the third step is to separate neon and helium, and get pure neon, pure helium products.

The purpose of crude neon and helium preparation is to remove nitrogen from raw materials and make them concentrated. Because the boiling points of nitrogen, neon and helium differ greatly, which is over 50 K, it can be separated in the condenser or auxiliary tower by using low pressure liquid nitrogen as cold source, make the nitrogen in the feed gas of neon and helium which have the pressure of the lower tower condense, and get that the content of neon and helium is about 1%_~3%, the rest is the mixture of crude neon and helium of nitrogen, and then enter the pure neon and helium preparation process. Some processes of crude neon and helium need to go through hydrogen removal and nitrogen removal. To remove hydrogen, use oxygen-added catalytic method to make hydrogen generate water, and then it is adsorbed and cleaned by dryer. The rest of the nitrogen can be adsorbed and removed by condensation or activated carbon at low temperature.

Since the difference of boiling points between neon and helium is about 23 K, it can be seen that the separation of pure neon and helium mixture can be conducted by condensation method. Because the solidification temperature of neon is-248.7 ℃, the solidification and freezing method can also be used to separate the gas-nitrogen and solid-neon.