Air separation

Air separation

Separation of atmospheric air into its primary constituents. Nitrogen, oxygen, and argon are the primary constituents of air. Small quantities of neon, helium, krypton, and xenon are present at constant concentrations and can be separated as products. Varying quantities of water, carbon dioxide, hydrocarbons, hydrogen, carbon monoxide, and trace environmental impurities (sulfur and nitrogen oxides, chlorine) are present depending upon location and climate. Typical quantities are shown in the table. These impurities are removed during air separation to maximize efficiency and avoid hazardous operation.

Three different technologies are used for the separation of air: cryogenic distillation, ambient temperature adsorption, and membrane separations. The latter two have evolved to full commercial status. Membrane technology is economical for the production of nitrogen and oxygen-enriched air (up to about 40% oxygen) at small scale. Adsorption technology produces nitrogen and medium-purity oxygen (85–95% oxygen) at flow rates up to 100 tons/day. The cryogenic process can generate oxygen or nitrogen at flows of 2500 tons/day from a single plant and make the full range of products.

Composition of dry air
Percent Parts per million
Component by volume Component by volume
Nitrogen 78.084 Carbon dioxide 350–400
tOxygen 20.946 Neon 18.2
Argon 0.934 Helium 5.2
Krypton 1.1
Xenon 0.09
Methane 1–15
Acetylene 0–0.5
Other hydrocarbons 0–5

Air separation is a major industry. Nitrogen and oxygen rank second and third in the scale of production of commodity chemicals; and air is the primary source of argon, neon, krypton, and xenon. Oxygen is used for steel, chemicals manufacture, and waste processing. Important uses are in integrated gasification combined cycle production of electricity, waste water treatment, and oxygen-enriched combustion. Nitrogen provides inert atmospheres for fuel, steel, and chemical processing and for the production of semiconductors.

References in periodicals archive ?
Maxima has two air separation plants and had sales of $23 million in 2006.
The technology company The Linde Group will build six major air separation units for Shenhua Ningxia Coal Industry Group Co.
Stephen Meholic, air separation equipment sales manager for Air Products, said, "This contract underscores our commitment to helping our customers with cost-effective air separation equipment, and other products and services.
This agreement is particularly timely, as BOC expands our own Midwest presence with a new air separation plant in Beloit, Wisconsin.
Air Products San Fu will build an air separation unit, pipelines and a bulk gas system to supply ultra-high purity (UHP) nitrogen and other bulk gases including oxygen, argon, helium and hydrogen to UMC s Phase Five to Phase Eight of their new 300mm wafer fab in one of Taiwan s largest science parks.
It also adds a specialty gas test laboratory and truck routing and delivery system on the East Coast to help us more fully utilize our recently acquired air separation plant.
An air separation plant will be built for the steel mill consisting of two cryogenic units with the capacity to produce 3,000 tons a day of industrial gases, primarily oxygen.
The deal will see Linde construct the country's largest air separation unit at the Phu My industrial park in Ba Ria (Vung Tau province).
At a contract signing ceremony held recently at ENAMI's headquarters in Santiago, Air Products Vice President James Strecansky said, "This contract with ENAMI underscores Air Products' commitment to helping our customers in Latin America and other parts of the world solve today's environmental challenges with cost effective air separation equipment, and our other products and services.
Praxair will design, build, operate, and own a state-of-the-art, large air separation unit (ASU) which is due to come on stream in 2009.
has started up a new air separation plant in the free trade zone of Gran Sabana, 50 km from Bogota, Colombia.
s (NYSE: APD) joint venture company in South Africa -- is investing over $60 million to build, own, and operate a new air separation facility at ISCOR's steel mill in Vanderbijlpark, South Africa.