Novel Pressure Swing Adsorption Cycle for the Production of Nitrogen from
Air
USCRF#00363
Principal Investigator: James Ritter, Ph.D., Department of Chemical Engineering
A new pressure swing adsorption (PSA) cycle for the production of nitrogen from air has been developed, based on an equilibrium-controlled separation using the commercially available molecular sieve - zeolite. In terms of both productivity and ease of operation, this new adsorption cycle should compete economically with the current state-of-the art PSA cycle for the production of nitrogen, which is based on a kinetically controlled separation using molecular sieve carbon. This new PSA cycle should produce nearly pure nitrogen, containing around 1,000 ppm of carbon dioxide, but no argon and only trace levels of oxygen. In contrast, the nitrogen produced from the kinetically controlled molecular sieve carbon based PSA cycle contains nearly pure nitrogen but also contains approximately 4 vol. % argon and trace levels of oxygen.
- In the food industry for blanketing produce, as this new PSA cycle should produce nearly pure nitrogen and only trace levels of oxygen.
- Applications in the airline industry exist for blanketing fuel tanks (especially fighter jets).
- In the chemical process industry for blanketing reactors and tanks containing flammable compounds
This method,
utilizing the molecular sieve zeolite adsorbent, has a higher capacity for
nitrogen than the molecular sieve carbon. Smaller beds means less capital
investment is required, and a higher capacity should also translate into
smaller high-to-low pressure ratios for operation.
This higher capacity should translate into a higher productivity (i.e., same
nitrogen production rate but with smaller beds) and potentially reduced
operating costs. These positive attributes of the new PSA cycle for nitrogen
production have the potential to supplant the state-of-the-art PSA processes
being widely used today for nitrogen production from air.
Researchers at the University of South Carolina have developed and demonstrated the potential of a two-bed PSA process that uses a reflux stream at the one end, with an intermediate feed position positioned between the two ends. Theoretically, this process has the potential to produce two pure products from a binary feed with the enrichment of the two components being constrained only by the mass balance.
A mathematical simulation has been carried out to verify expectations of experiment. Outcome of simulation has been favorable and warrants further development with the aid of a physical experiment.
Patent pending.
A physical model is planned to confirm findings of mathematical simulation.