Separation of Gases by Enhanced Upstream Diffusion

Abstract

Small amplitude oscillations have been shown to raise the diffusional flux in cylindrical tubes by orders of magnitude. The flux is especially high when the oscillation frequency is tuned to the size of the capillaries and to the properties of the gases involved. The process has been shown to permit separation of molecules of different molecular weight. The separation factor approaches, but is not equal to, the square root of the ratio of the molecular weight of the molecules involved. Hertz showed the separation can be enhanced by diffusion in a convective counterflow; it may then exceed the ratio of the square roots. We have combined oscillations and counterflow to obtain high yield and high separation. The results are encouraging. The separation is 20 to 40 times better than our past results. When applied to a simulated cascade, the savings in equipment and operational costs would be substantial.