Pressure-swing adsorption purging

Figure 2. Combined pressure-swing, non-adsorbed-product-purge cycle (pressure-swing adsorption).

After further heat recovery, final cooling and condensate separation (6), the gas is sent to the pressure swing adsorption (PSA) unit (7). Loaded adsorbers are regenerated isothermally using a controlled sequence of depressurization and purging steps. 

Pressure swing adsorption (PSA) on zeolite molecular sieves (see Section 4.3.2.6) may be also used for hydrogen recovery from purge gas [761]. The process, originally developed by Union Carbide under the name HYSIV, is now marketed as Polybed PSA by UOP [970], [973], [974], PSA technology is also offered by Linde and other companies. If required, the process also offers the possibility to supply pure hydrogen from... 

Sood S K, Fong C, Kalyanam K M, Busigin A, Kvelton O K and Ruthven D M (1992), A new pressure swing adsorption (PSA) process for recovery of tritium from the ITER solid ceramic breeder helium purge gas . Fusion Technol, 21, 299. 

Liquid Adsorption. Adsorption takes place selectively because of (1) polarity differences between adsorbate and unadsorbed liquid, or (2) differences in size and structural characteristics of molecules. In the first category we may mention activated carbon, in the second one the molecular sieves. Liquid adsorption is suitable for both recovery of small amounts from dilute solutions, and for bulk separations. Purification is feasible with very selective adsorbent. Recovery of adsorbate and regeneration of the adsorbent may be performed by (1) Thermal Swing Adsorption, (2) Pressure Swing Adsorption, (3) inert-purge swing, or (4) displacement desorption. 

Kg. 9.2-2 Pressure swing adsorption unit with four fixed beds, (a) pressure rise, (b) depressurization, (c) depressurization - purging... 

ADSORBED PRODUCT PLUS LESS-ADSORBED PRODUCT PURGE GAS FIGURE 12.4-6 Pressure-swing adsorption (PSA) cycle. 

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