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Application of a Flux-Blocking Layer to Minimize Chemical Expansion Strain

IP.com Disclosure Number: IPCOM000019426D
Publication Date: 2003-Sep-12
Document File: 1 page(s) / 22K

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Abstract

Oxygen can be recovered from air at high temperatures by passing hot, oxygen-containing gas, preferably air, over non-porous, mixed conducting ceramic membranes. These membranes, known in the art generically as ion transport membranes (ITMs), utilize an oxygen partial pressure differential across the membrane to cause oxygen ions to migrate through the membrane.

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Application of a Flux-Blocking Layer to Minimize Chemical Expansion Strain

         Oxygen can be recovered from air at high temperatures by passing hot, oxygen-containing gas, preferably air, over non-porous, mixed conducting ceramic membranes. These membranes, known in the art generically as ion transport membranes (ITMs), utilize an oxygen partial pressure differential across the membrane to cause oxygen ions to migrate through the membrane.

         Membranes can be fabricated as tubes or flat plates that are arranged in modules for efficient contact with the hot compressed air. High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules. A comprehensive review of ion transport membranes is given by J. D. Wright and R. J. Copeland in Report No. TDA-GRI-90/0303 prepared for the Gas Research Institute, September 1990.

Exhibiting a phenomenon known as chemical expansion, the materials used in ITM membrane fabrication expand when the oxygen partial pressure is decreased. Since operating membranes experience an oxygen activity gradient, they will be affected by a differential expansion. This expansion can produce potentially damaging stresses that increase the risk of failure.

Certain areas of the membrane assembly function as structural components and do not transport oxygen. These areas are especially vulnerable to chemical expansion stresses. To increase the structural reliability of assemblies, it is necessary to reduce the expansion-induced strai...