PSA process separation

White, D. H., Jr., Conpressed Air and Gas Purification and Fractionation for High Purity Applications by Improved PSA Processes, Separ. Sci. Technol, 43, 2298-2306 (July 2008). 

One version of the UOP IsoSiv process uses PSA to separate normal paraffins from branched and cycHc hydrocarbons in the to range. 

Relatively new methods for separating helium from natural gas use pressure swing adsorption (PSA) processes to recover helium at better than 99.99% purity. This type of process is probably less costiy for the production of gaseous helium but might be uneconomical for liquefied helium production. The PSA process is widely used to produce specification pure helium from 85+% cmde helium in conjunction with cryogenic enrichment of the ca 50% helium raffinate. 

Pressure Swing Adsorption. A number of processes based on Pressure Swing Adsorption (PSA) technology have been used in the production of carbon dioxide. In one version of the PSA process, CO2 is separated from CH using a multibed adsorption process (41). In this process both CH4 and CO2 are produced. The process requires the use of five adsorber vessels. Processes of this type can be used for producing CO2 from natural gas weUs, landfiU gas, or from oil weUs undergoing CO2 flooding for enhanced oil recovery (see Adsorption, gas separation). 

Adsorption Processes. More recendy, pressure swing adsorption (PSA) processes utilizing a high selectivity copper adsorbent have been utilized to effectively separate carbon monoxide from blast furnace gas and coke oven gas (97—101). 

KURASEP [Kuraray Separation] A process for separating nitrogen from air by a variant of the PSA process, using carbon molecular sieve as the adsorbent. Developed by Kuraray Chemical Company. 

LO-FIN [Last out-first in] A version of the PSA process for separating hydrogen from other gases. It includes a unique gas-retaining vessel which preserves the concentration gradient in one stream before using it to repressurize another bed. Developed jointly by Toyo Engineering Corporation and Essex Corporation. 

MOLPSA-nitrogen [Molecular sieve pressure swing adsorption] A version of the PSA process for separating nitrogen from air, developed by Kobe Steel. Most PSA processes for nitrogen use molecular sieve carbon as the adsorbent, but this one uses zeolite X. Water and carbon dioxide are first removed in a two-bed PSA system, and then the nitrogen is concentrated and purified in a three-bed system. 

NOVOX Not a process, but a trademark used by BOC to designate its PSA process for separating oxygen from air. 

In PSA air separation the adsorbent, despite its low loading and shallow slope, is actually adsorbing and removing from the gas phase 79mol% of the dry feed stream. In H 2 purification there are generally a few more contaminants to remove, the H2 is essentially non-adsorbed, high purity and recovery of the product gas is quite important to the process economics. 

Practical concerns, specifically mass transfer, Umit the recovery to values in the high 70% range. All this said, the vast majority of operating air separation units are the small capacity medical oxygen concentrators. These operate under either PSA or VSA or trans-atmospheric process cycles. The key objective for medical O2 is small unit size and power consumption prior to the push for portability was a secondary consideration. There are many such PSA air separation units that operate at recoveries as low as 35%. 

As with air separation the purification of hydrogen via a PSA process is also a well developed field. The market place is highly competitive and UOP competes with... 

Hydrogen separations with metal hydrides can be viewed as complementary technology to cryogenic and adsorption (PSA) processes. Attributes of this new process are listed in Table II,... 

Pressure swing adsorption (PSA) processes are widely applied industrially for gas separations. Applications are numerous and include hydrogen and helium recovery and purification, air drying, the production of oxygen from air, and the separation of normal paraffins from isoparaffins. 

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