Separation of krypton and xenon by selective permeation
Article first published online: 17 JUN 2004
Copyright © 1980 American Institute of Chemical Engineers
Volume 26, Issue 6, pages 881–890, November 1980
How to Cite
Stern, S. A. and Leone, S. M. (1980), Separation of krypton and xenon by selective permeation. AIChE J., 26: 881–890. doi: 10.1002/aic.690260602
- Issue published online: 17 JUN 2004
- Article first published online: 17 JUN 2004
- Manuscript Accepted: 30 APR 1980
- Manuscript Revised: 16 APR 1980
- Manuscript Received: 10 MAY 1978
The objective of this investigation was to study the separation of krypton and xenon from nuclear reactor atmospheres by selective permeation through silicone rubber capillaries. Effective permeability coefficients for pure krypton xenon, nitrogen, and oxygen were determined between 0 and 40°C and at pressure differences across the capillary walls (Δp) of up to 3.45 × 105 N/m2 (50 psi). The silicone rubber capillaries had an O.D. of 635 μm (0.025 in.) and an I.D. of 305 μm (0.012 in.), and were pressurized externally. The effective permeability coefficients decreased with increasing Δp, due to the elastic deformation of the capillaries, in general agreement with a deformation analysis of thick-walled elastic tubes.
Gas separation studies were made with a Kr-Xe-N2-O2 mixture in a permeator containing a bundle of silicone rubber capillaries. The permeator had an effective permeation area of 0.480 m2 (5.165 ft2) at a packing density of 4132 m2m3 permeator volume (1260 ft2/ft3), and was operated in a countercurrent mode. The separation studies were conducted at −10 and 20°C and at three Δp values. The separation achieved in the permeator at Δp's of 1.38 × 105 N/m2 (20 Ib/in.2) and 2.07 × 105 N/m2 (30 Ib/in.2) was in good agreement with that predicted from a theoretical model of a permeation stage with countercurrent flow. At 3.45 × 105 N/m2 (50 Ib/in.2), the separation approached that predicted from a “perfect mixing” model. This behavior probably was due to local collapses of the capillaries at weak spots in their walls, as was evidenced also by a sharp increase in the axial pressure drop inside the capillaries.