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Production of Nitrogen or Inert Gas from ITM Oxygen Generator Residue Gas

IP.com Disclosure Number: IPCOM000019425D
Publication Date: 2003-Sep-12
Document File: 3 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

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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Production of Nitrogen or Inert Gas from ITM Oxygen Generator Residue Gas

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

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 High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules.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

In applications requiring high purity oxygen and an inert gas mixture; a controlled, low oxygen inert gas; or nitrogen, the ITM oxygen process can be adapted to yield both products. The permeate stream from the ITM process will be the oxygen product, and the non-permeate "residue gas," which still contains some level of oxygen, will be the feed for production of the inert stream. This feed will pass through a second ITM unit that is swept with natural gas, syngas, clean fuel gas, or another mixture of light hydrocarbons that will react with the oxygen permeating through the membrane. The reaction on the permeate side of the second ITM unit will produce CO, CO2, H2, and water vapor, creating a very low oxygen partial pressure atmosphere that greatly reduces the oxygen content in the non-permeate stream of the second ITM. The second ITM unit can be operated to complete or partial oxidation on the reducing gas side.

Ideally, the second ITM unit is loaded with steam reforming catalyst on the permeate side and provision is made for the blending of water vapor into the hydrocarbon "sweep" gas. This will allow concurrent steam reforming and hydrocarbon oxidation to occur. Adjustment of the water injection can also be used to control temperature increases in the second ITM. The permeate produced by the second ITM can be sent to the combustor as fuel. The oxygen-depleted non-permeate can then be used as is or, if some reliable degree of nitrogen purity or other inert composition is required, cleaned up by means of driers and a separation process. Figure 1 is a simplified depiction of this application.

 
 

Figure 1. ITM N2-O2 System

 
 

The use of oxygen ITM non-permeate in the production of nitrogen or low oxygen/inert gas can be integrated in a larger process, as shown in Figure 2. In this schem...