Helium is mainly separated and extracted from helium-containing natural gas by cryogenic condensation, and further refined by combining adsorption, membrane permeation and other technologies. The following are specific steps and methods:
Main extraction method
Natural gas cryogenic condensation fractionation method (industrial mainstream method):
- Pretreatment: Remove impurities such as hydrogen sulfide, carbon dioxide, and water from natural gas, commonly using chemical absorption (such as amine solvents) and molecular sieve adsorption.
- Liquidation separation: The natural gas is gradually cooled to below -160°C through a multi-stage cooling system to liquefy high-boiling point components such as methane and ethane. Helium is separated in a gaseous state due to its lowest boiling point (-268.93°C).
- Purification: The crude helium separated initially needs to be further removed by adsorption (such as activated carbon, molecular sieves), membrane permeation (selective permeation of helium) or cryogenic distillation to remove residual impurities, and the final purity can reach 99.999%. Other
auxiliary technologies:
Membrane permeation method: Utilize the high permeability of helium in special membrane materials for separation, suitable for smaller scale or supplementary purification.
Adsorption method: Adsorb and desorb impurity gases through pressure swing adsorption (PSA) cycle to increase helium concentration.
Supplementary explanation
Air separation method (air separation): Because the helium content in the air is only 0.0005%, large-scale air separation equipment is required for extraction, which is extremely costly and less used.
Radioactive mineral method: Uranium ore decay produces helium, but due to the radioactive risk and low yield, it is limited to special occasions.
Core conclusion: Industrial helium extraction is highly dependent on helium-containing natural gas resources. Preliminary separation is achieved through low-temperature condensation, and then refined into high-purity helium by combining adsorption, membrane permeation and other technologies.
