This market covers mostly the drying and purification of gases such as air, oxygen, nitrogen, carbon dioxide, helium, hydrogen, etc. by manufacturers of these gases.
For example, air is compressed and sent through a series of heat exchangers to very low temperatures so that nitrogen and oxygen are separated and liquefied. Before going through these exchangers, the water and CO2 must be removed by an adsorption system or freeze-up will occur. Over 550 billion cubic feet of nitrogen and 350 billion cubic feet of oxygen were produced by this method in 1985. The major end uses for these gases are blanketing atmospheres for the chemical industry, electronics, manufacturing, enhanced oil recovery, metals treating and processing, and metals manufacturing and fabricating.
Carbon dioxide is another gas that is dried by solid adsorption. Over 4 million tons a year of CO2 are produced. It is recovered from synthesis gas in ammonia production, from refinery production of hydrogen, from fermentation processes and from natural wells. The main uses of carbon dioxide are refrigeration, beverage carbonation, urea manufacture, and enhanced oil recovery. Carbon dioxide is dried for production purposes. The presence of moisture in carbon dioxide can also cause process line freeze-up at high pressures along with corrosion problems.
Both helium and hydrogen are also dried and purified before liquefaction. Both are used for rocket propulsion.