Adsorption displacement-purge cycle

Regenerative adsorption units can be operated by a thermal-swing cycle, pressure-swing cycle, displacement-purge cycle, or inert-purge cycle. Combinations of these are frequently employed. 

Displacement-Purge Cycle This cycle, which is somewhat similar to the previous one, differs from it in that a gas or vapor which adsorbs about as strongly as the adsorbate is used to remove the adsorbate (see Figure 1) Removal is thus facilitated both by adsorbate partial-pressure reduction in the fluid around the particles and by competitive adsorption of the displacement medium. As with the inert-purge cycle, the maximum delta loading is the equilibrium loading ... 

Steps. A purge-swing cycle usually has two steps, adsorption and purge. Sometimes, a cocurrent purge is added. After the adsorption step has been completed and the less selectively adsorbed components have been recovered, an appreciable amount of product is still stored in the bed. A purge cocurrent to feed can increase recovery by displacing the fluid held in the voids. 

Gas bulk-separation processes consist mostly of pressureswing adsorption (PSA) variations and displacement-purge and Inert-purge processes Recently, however, a chromatographic cycle has been commercialized Below, these cycles will be discussed ... 

A major requirement for a successful displacement purge gas/vapor, the displacer, however, is that it should not be too strongly adsorbed compared to the feed species to be desorbed. If it is, then it would be difficult to desorb it during the adsorption part of the next cycle. In fact, ideally, it should have an almost identical affinity for adsorption on... 

A purge-swing adsorption cycle is usually considered to be one in which desorption takes place at the same temperature and total pressure as adsorption. Desorption is accomplished either by partial-pressure reduction using an inert gas purge or by adsorbate displace-... 

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