Pressure swing adsorption purification

H. A. Stewart and J. L. Heck, Hydrogen Purification By Pressure Swing Adsorption, Union Carbide Corp., Linde Division, New York. 

Figure 4.1. A process for producing hydrogen by steam reforming of hydrocarbons (1) reforming furnace (2,3) purification section, (4) shift converter, (5) pressure swing adsorption.

In most hydrogen plants, a pressure-swing adsorption (PSA) system is used for hydrogen purification. In these plants, a major portion of reformer fuel is PSA offgas with a hydrocarbon stream for makeup fuel. 

Cyclic adsorption processes such as parametric pumping, cycling zone adsorption and heatless adsorption have received much attention both theoretically and experimentally in the past several years (3j. Skarstrom (4J has reviewed applications of heatless adsorption (synonymous with pressure swing adsorption) to air drying, hydrogen purification and air fractionation. 

Recovery and Purification of Light Gases by Pressure Swing Adsorption... 

A cell model is presented for the description of the separation of two-component gas mixtures by pressure swing adsorption processes. Local equilibrium is assumed with linear, independent isotherms. The model is used to determine the light gas enrichment and recovery performance of a single-column recovery process and a two-column recovery and purification process. The results are discussed in general terms and with reference to the separation of helium and methane. 

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. 

The equations for a local equilibrium cell model of pressure swing adsorption processes with linear isotherms have been derived. These equations may be used to describe any PSA cycle composed of pressurization and blowdown steps and steps with flow at constant pressure. The use of the equations was illustrated by obtaining solutions for a single-column recovery process and a two-column recovery and purification process. The single-column process was superior in enrichment and recovery of the light component at large product cuts. The two-column process was superior at small cuts ... 

FIGURE 1 Pressure swing adsorption for oxygen generation and purification. 

Pressure injection bismuth nanowires, 175-177 experimental setup, 174 nanowire fabrication, 173-177 template requirements, 175 Washburn equation, 174-175 Pressure swing adsorption, adsorption, 80 Protein microtube-mediated synthesis, nanostructured materials, 15-16 Purification, olefin-diene, 117... 

In modern plants, a Pressure Swing Adsorption (PSA) unit replaces the complete LTS, the CO2 stripping section and the final purification. 

Pure Hydrogen Generation with Pressure Swing Adsorption (PSA) Purification... 

Carbon monoxide is first stripped off particulate matter in a cyclone separator or in a scrubber. Scrubbing also removes tar or heavy hydrocarbon fractions. Acidic gases, if present, are removed by absorption in monoethanol amine or in potassium carbonate. This pretreated gas is sent to the next section for further purification. Commercial processes for final purification are based on the absorption of carbon monoxide by salt solution, low-temperature condensation, or fractionation, or by pressure-swing adsorption using a solid material. 

Description The generic flowsheet consists of feed pre-treatment, prereforming (optional), steam-HC reforming, shift conversion and hydrogen purification by pressure swing adsorption (PSA). However, it is often tailored to satisfy specific requirements. 

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