Oxygen Cooling Strategies in Ion Transport Membrane Vessels
Publication Date: 2005-Oct-07
The IP.com Prior Art Database
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 High-purity oxygen permeate and nitrogen-enriched non-permeate products are withdrawn from the modules.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.
ITM’s produce oxygen at high temperatures, typically 800-900°C. The oxygen is produced in conjunction with an inert sweep gas, or as a pure product at sub-ambient pressure. Depending on the specific application of the ITM, recovering the heat energy from the oxygen may not be advantageous. In those applications where heat recovery is not advantageous, the following ideas are proposed to effect cooling of the oxygen stream.
One idea is to quench the oxygen by mixing it with a cooler substance. To maintain the purity of the oxygen, one can mix the oxygen with cooled oxygen. Alternatively, the oxygen can be mixed with a cooled inert substance, such as water.
The mixing can take place within the pressure vessel that houses the ITM’s. The ITM vessel can be designed to house the membranes in their entirety, as well as the metal piping and/or manifolds that immediately carry the oxygen product away from the membrane. If the mixing to effect oxygen cooling takes place inside the vessel, the vessel may necessarily house a second manifold to carry the quench stream to the product oxygen. The mixing of the quench stream with the product oxygen can take place at the discharge port of each ITM or in a common header that accepts product oxygen from multiple ITM’s. Piping from the second (quench) manifold must connect with the oxygen manifold/piping according to where the mixing takes place. Figure 1 is a schematic of an ITM vessel cross-sec...