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Vacuum swing adsorption
Vacuum Swing Adsorption (VSA) is a non-cryogenic gas separation technology. Using special solids, or adsorbents, VSA segregates certain gases from a gaseous mixture under minimal pressure according to the species' molecular characteristics and affinity for the adsorbents. These adsorbents (e.g., zeolites) form a molecular sieve and preferentially adsorb the target gas species at near ambient pressure. The process then swings to a vacuum to regenerate the adsorbent material.
VSA differs from cryogenic distillation techniques of gas separation as well as pressure swing adsorption (PSA) techniques due to the fact that it operates at near-ambient temperatures and pressures.
Additional recommended knowledge
Advantages of VSA over PSA
The simplicity of the VSA process allows for greater efficiency and cost savings, and less maintainence vis-à-vis PSA systems. The VSA process extracts maximum sieve and power efficiencies. The integrated rotary lobe blower, which also serves as a vacuum regenerator, results in low feed pressure. The dramatically lower pressure swings in the VSA system eliminate the need for a feed air compressor, which translates into lower power consumption for VSA systems. As a result, power savings of as much as 50% can be achieved.
The design simplicity and efficiency that VSA technology offers has generated products that are more energy- and cost-efficient than traditional gas separation units. VSA processes are used at refineries, chemical and petrochemical plants, water treatment facilities, and landfills. VSA technology is used to purify air, soil, water, and hydrogen, and to manufacture oxygen, nitrogen, and hydrogen.
VSA technology plays an increasingly important role in the commercial production of oxygen. Oxygen concentrators that use VSA processes are a more lucrative and reliable option than oxygen cylinders for many industries. Its mobility and constant supply of oxygen makes it a perfect choice for governments and aid organizations in their emergency medicine and disaster relief operations, as well as for district hospitals in developing nations. Other commercial applications of oxygen concentrators include the fields of aquaculture and high-altitude work environments, including in the mining industry or the Goldmud-Lhasa railroad in Tibet.
For the oil and gas industry, the production of liquid nitrogen via PSA technology is key in cases where a high nitrogen flow rate and/or high discharge pressure is required. As an inert gas, nitrogen is preferred over air for cleaning out newly drilled wells as well as maintaining old wells. In addition, nitrogen is used for fracturing, pipeline purging and drying, cementing, and pressure maintenance.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Vacuum_swing_adsorption". A list of authors is available in Wikipedia.|