Skarstrom pressure swing adsorption cycle

Figure 13. Schematic flow diagram for two column Skarstrom pressure swing adsorption cycle for gas drying.

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. 

FIGURE 11 Sequence of steps in a two-bed pressure swing adsorption system, (a) Skarstrom cycle, (b) modified cycle for production of nitrogen using a carbon molecular sieve adsorbent. 

Figure 18-11. Pressure swing adsorption (A) steps for single column in Skarstrom cycle, (B) use of two columns in parallel for continuous feed and product. Period of feed step = period of blowdown +...

In the original form of the process, pressure swing adsorption was run slowly, near equilibrium. The concentrations obtained were then less a function of mass transfer and hence largely independent of diffusion. More recently, pressure swing adsorption beds have operated much more rapidly. For example, in Skarstrom s original work, the cycle time for the beds was around 20 minutes in more recents efforts, the cycle time can be 10 seconds. With these rapidly cycled beds, the separation depends not only on differences in adsorption but also on differences in mass transfer. The extensions of this rapid process, beautifully detailed by Yang, are beyond the scope of this chapter. I did want to mention the process because I believe it is still emerging. 

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