Air separation Non-cryogenic processes

Pressure swing adsorption separates oxygen or nitrogen from air without liquefaction.The process operates at ambient temperature; the zeolite (molecular sponge) is exposed to high-pressure air, which then releases the air and releases an adsorbed film of the desired gas.Compressors are greatly reduced in size compared to liquefaction plants, and portable oxygen concentrators are manufactured in this way to provide oxygen-enriched air for medical purposes.Pressure swing adsorption is a similar process; the product gas is precipitated from the zeolite at subatmospheric pressure.Membrane technology can provide an alternative, low energy consumption method of air separation.For example, various methods of oxygen generation are being explored.For example, a polymer membrane operating at ambient or warm temperatures may be able to generate oxygen-enriched air (25-50% oxygen).Ceramic membranes can provide high purity oxygen (90% or better), but require higher temperatures (800-900 degrees Celsius) to operate. These ceramic membranes include ion transport membranes (ITM) and oxygen transport membranes (OTM).Air Products and Chemicals Inc and Praxair are developing flat ITM and tubular OTM systems.

Membrane gas separation is used to deliver oxygen-depleted and nitrogen-enriched gases instead of air to fill fuel tanks that line jet aircraft, greatly reducing the chance of accidental fires and explosions.Instead, membrane gas separation is currently used to provide oxygen-enriched air to pilots flying at high altitudes in aircraft without pressurized cabins.Oxygen-enriched air can be obtained by taking advantage of the different solubility of oxygen and nitrogen.Oxygen is more soluble in water than nitrogen, so if air is degassed from water, a 35% flow of oxygen can be obtained.

Applications

Rocket:

Liquid oxygen for companies like SpaceX.Helium extracted by air separation is also used by NASA for inert spacecraft.

Steel:

In steelmaking, basic oxygen steelmaking requires oxygen.Modern basic oxygen steelmaking uses nearly two tons of oxygen per ton of steel.

Ammonia:

Nitrogen used in the production of ammonia in the Haber process.

Gas:

Coal gasification projects require a large amount of oxygen; some projects have low-temperature devices with a daily output of 3,000 tons.

Inert gas:

Nitrogen storage tank inertization for ships and oil product storage tanks, or to protect edible oil products from oxidation.