UOP PolybedTM PSA Systems for Gas Extraction and Purification

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The Pressure Swing Adsorption (PSA) process isbased on the principle that adsorbents are capableof selectively adsorbing impurities.The impuritiesare adsorbed in a fixed-bed adsorber at high pressureand desorbed by “swinging” the adsorber from thefeed to the tail gas pressure and by using a high-puritypurge. Typically the desired component is notadsorbed and is recovered at high purity.

UOP’s Polybed PSA system offers:

� High reliability (greater than 99.8% on-stream time)

� Minimal manpower requirements due to auto-matic operation, which can include automaticstart-up, capacity control, tail gas control,switchover, pressure control, and product purity control

� Reduced equipment costs and enhanced performance based on high performance adsorbents and advanced PSA cycles

� Lower operating and equipment costs for down-stream process units due to the availability of ahigh-purity product gas

� Flexibility to process more than one feedstockand maintain product purity and recovery dur-ing changing conditions

� Minimal feed pretreatment and utility requirements

� Adsorbents last for the life of the mechanicalequipment (more than 30 years)

� Reduced plot requirements, fast delivery times,and low installation costs based on the modulardesign

� Worldwide service and support

Operation

UOP’s Polybed PSA systems are designed to besafe, efficient, and economical.

A PSA system operates as a batch process; however,multiple adsorbers operating in a staggeredsequence are used to produce constant feed,

product, and tail gas flows. Regardless of the num-ber of adsorber vessels, all Polybed systems followthe five-step pressure-swing cycle shown next. Thered area represents the impurities, and the blue areathe product.

Step 1 Adsorption

The feed gas enters an adsorber at ahigh pressure, impurities areadsorbed, and high-purity product isproduced. Flow is normally in theupward direction. When an adsorberhas reached its adsorption capacity, itis taken off-line, and the feed automat-ically switched to a fresh adsorber.

Feed

Product

UOP Polybed PSA Systems for Gas Extraction and Purification 2

Step 2 Co-current depressurization

To recover the product trapped in theadsorbent void spaces, the adsorberis co-currently (in the direction of feed flow) depressurized. The productgas withdrawn is used internally to repressurize and purge other adsorbers.

Step 3 Counter-current depressurization

At the conclusion of the co-currentdepressurization step, the adsorbentis partially regenerated by counter-currently depressurizing the adsorberto the tail gas pressure, and therebyrejecting the impurities.

Step 4 Purge

The adsorbent is purged with a high-purity stream (taken from anotheradsorber on the co-current depressur-ization step) at a constant pressure tofurther regenerate the bed.

Step 5 Repressurization

The repressurization gas is providedfrom the co-current depressurizationstep and a slipstream from the prod-uct. When the adsorber has reachedthe adsorption pressure, the cycle hasbeen completed, and the vessel isready for the next adsorption step.

Commercial experience

Since commercialization in 1966, UOP has providedover 700 PSA systems in more than 60 countries.These systems have found application in the refining,petrochemical, polymer, steel, and power generationindustries. The Polybed PSA system has demon-strated exceptional economic value in many applications, such as recovery of hydrogen from

refinery off-gases, recovery of monomers in polyolefin plants, extraction of hydrogen from gasification syngas, purification of helium forindustrial gas use, adjustment of synthesis gas forammonia production, purification of methane forpetrochemicals production, and H2/CO ratio adjustment for syngas used in the manufacture of oxo-alcohols.

Feed conditions typically range from (seven to 70kg/cm2g) (100 to 1,000 psig), with concentrations of the desired component from 30 to 98+ mol-%.System capacities range from less than one to morethan 350 MM SCFD (less than 100 to more than390,000 Nm3/h).

UOP:

� Optimizes the integration of PSA technologywithin your plant.

� Continually improves existing technologyto meet your changing process needs.

� Develops new applications to meet your newchallenges.

� Provides ongoing technical services and supportafter startup.

� Keeps you informed on the latest developmentsand advancements in our technology throughseminars and conferences.

� Provides revamp services.

For more information

For more information, contact your local UOP representative or our Des Plaines sales office:

e-mail: info@uop.comfax: +1-847-391-2253phone: +1-847-391-2000

To NextVessel

Tail Gas

Purge

Tail Gas

© 2007 UOP LLC. All rights reserved.The information in this document should not be construed as a representation for which UOP assumes legal responsibility, or an authorization or recommendation to practice a patented invention without a license.UOP 4810-1 0907

UOP LLC25 East Algonquin RoadDes Plaines, IL 60017-5017 U.S.A.www.uop.com