ASHRAE - American Society of Heating@ Refrigerating and Air-Conditioning Engineers@ Inc.
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ASHRAE REFRIGERATION SI CH 47-2010
Scope
GENERAL APPLICATIONS The application of cryogenic engineering has become extensive. In the United States@ for example@ nearly 30% of the oxygen produced by cryogenic separation is used by the steel industry to reduce the cost of high-grade steel@ and another 20% is used in the chemical process industry to produce a variety of oxygenated compounds. Liquid hydrogen production has risen from laboratory quantities to over 2.1 kg/s. Similarly@ liquid helium demand has required the construction of large plants to separate helium from natural gas cryogenically. Energy demand likewise has accelerated construction of large base-load liquefied natural gas (LNG) plants. Applications include high-field magnets and sophisticated electronic devices that use the superconductivity of materials at low temperatures. Space simulation requires cryopumping (freezing residual gases in a chamber on a cold surface) to provide the ultrahigh vacuum representative of conditions in space. This concept has also been used in commercial high-vacuum pumps. The food industry uses large amounts of liquid nitrogen to freeze expensive foods such as shrimp and to maintain frozen food during transport. Liquid-nitrogen-cooled containers are used to preserve whole blood@ bone marrow@ and animal semen for extended periods. Cryogenic surgery is performed to treat disorders such as Parkinson's disease. Medical diagnosis uses magnetic resonance imaging (MRI)@ which requires cryogenically cooled superconducting magnets. Superconducting magnets are now an essential component in high-energy accelerators and target chambers. Finally@ the chemical processing industry relies on cryogenic temperatures to recover valuable heavy components or upgrade the heat content of fuel gas from natural gas@ recover useful components such as argon and neon from air@ purify various process and waste streams@ and produce ethylene from a mixture of olefin compounds.