Adsorptive separation performance improvements resulting from enhanced adsorption rate

IEC 102

Mark W. Ackley, Gas Separations R&D, Gas Separations R&D, Praxair, Inc, 175 East Park Drive, Tonawanda, NY 14151
Commercial adsorptive gas separations must be continuously improved to remain competitive with other separation processes. This is particularly evident in the production of oxygen using pressure swing adsorption. Significant advances in this process have occurred over the past three decades by the introduction of highly exchanged, low Si:Al LiX zeolite, vacuum desorption and lower pressure ratios. A more recent development allows further improvement in process performance by increasing the rate of adsorption. The macropore diffusivity of the adsorbent, the particle size and porosity are combined to increase the mass transfer coefficient and thus increase the rate of adsorption during the separation process. The increased rate of adsorption enables shorter cycles, shallower beds and lower pressure ratios. The net result to process performance is lower oxygen product cost, smaller bed size factor and lower specific power with only a modest decrease in product recovery.