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Cool Seal and Modifications to NREC Vitiated Air Combustor for ITM O2 Disclosure Number: IPCOM000124742D
Publication Date: 2005-May-05
Document File: 3 page(s) / 36K

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Cool Seal and Modifications to NREC Vitiated Air Combustor for ITM O2

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  High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules.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. 

Ceramic Ion Transport Membranes (ITM's) for tonnage oxygen production are advantageously arrayed in a flow duct that is located inside a pressure vessel.  Air or other oxygen-containing gas is pressurized to 1-100 bar, and at least a portion of the gas is heated to 750-1000°C and is passed into the pressure vessel through the duct and over the surfaces of membrane modules.  Oxygen is extracted from the heated stream by the modules, and the resulting oxygen-depleted gas flows out of the duct and exits the pressure vessel.  The oxygen extracted by the modules can pass from the modules into a network of metal pipes; at least one of the pipes penetrates the wall of the pressure vessel, and the oxygen is thereby carried out of the pressure vessel as a separate product stream.

The interface between the ceramic modules and the piping network is mediated by a ceramic-to-metal seal.  For some seal designs, especially those relying on the integrity of metal foils or brazes, the seal is advantageously operated at a temperature lower than the prevailing hot, oxygen-containing gas feed flow to the modules to maintain seal integrity.  For that reason, it is advantageous to locate the seal outside the direct flow of the hot feed gas.  To maintain a temperature of the seal lower than that of the duct, the duct can be thermally insulated, and the metal-ceramic interface region can be located in the space outside the duct, but inside the pressure vessel.  Alternatively, the metal-ceramic interface region can be located inside an insulation layer located outside the duct.

In place of the concepts described above or to augment them, the seal may be actively cooled.  One option for active cooling of the metal-ceramic interface is to direct a portion of the pressurized, unheated, oxygen-containing gas over the m...