MXPA98005071A - Hybrid systems of ionic solid electrolytic driver to purify iner gases - Google Patents

Abstract

The present invention relates to: A process for removing oxygen from a feed gas stream to produce a retentate gas stream depleted in oxygen by supplying the feed gas stream to a mass oxygen separation system to eliminate oxygen to produce a gas stream of crude product depleted in oxygen and a first permeate residual stream containing oxygen, and supplying the gas stream of spent oxygen product to a separator having a primary ion transport membrane to produce a second permeate residual current and retentate gas stream exhausted in oxygen. A reactive purge gas is added to react with a portion of the oxygen that penetrates through the primary ion transport membrane and purges the permeate side of the primary ion transport membrane, and / or a recycle gas stream that comprises at least a portion of a gas stream produced during the process is added to at least one other stream of g

Description

HYBRID SYSTEMS OF IONIC CONDUCTOR OF SOLID ELECTROLYTE FOR PURIFYING INERT GASES FIELD OF THE INVENTION The invention relates to an apparatus and process for separating oxygen from a mixed gas feed stream and, more particularly, to an apparatus and process that utilizes a bulk oxygen separation system and an ionic conductive separator. solid electrolyte to separate oxygen from the air to produce nitrogen or another inert gas of high purity. BACKGROUND OF THE INVENTION For many years, non-cryogenic bulk oxygen separation systems, for example, organic polymer membrane systems, have been used to separate selected gases from air and other gas mixtures. Composite porous fibers which employ these organic polymer membranes can have separation factors that favor the permeation of oxygen over nitrogen by a factor of ten or less. For years, many processes have been devised that employ such polyaic membranes for the production of oxygen and particularly nitrogen from ambient air, with the advantage of this penetration differential. Systems using polymer membranes to separate oxygen from nitrogen are described in, for example, Prasad, U.S. Patent. No. 5,378,263, entitled "High Purity Membrane Nitrogen". Other non-cryogenic bulk oxygen separation systems utilize pressure swing absorption (AOP) to separate selected gases. Polymeric membrane dryers used as purifiers for nitrogen production by AOP are described in, for example, Haas et al. , Patent of E.U. No. 5,004,482, entitled "Production of High Purity Dry Nitrogen". Air is a mixture of gases that may contain varying amounts of water vapor and, at sea level, has the following approximate composition by volume: oxygen (20.9%), nitrogen (78%), argon (0.94%), with the rest consisting of traces of other gases. The presence of argon in a nitrogen product is not important for many applications of this gas and therefore is not frequently removed from nitrogen. Polymer membrane systems have been used for a long time for the separation of nitrogen from the air. Such TM membrane systems include the NitroGEN systems developed by Praxair, Inc., which are used for the commercial production of nitrogen from air. The purity of the nitrogen product depends on the number of penetration "stages" used. For low purities, a one-stage process is sufficient. Higher purity can be obtained in a two-stage process where the permeate from the second stage (which is enriched in nitrogen compared to air) is recycled to the feed compressor. By adding a third stage, by recycling the permeated streams of the second and third stages to the feed gas stream, an even higher purity can be obtained. The oxygen content in the product nitrogen can be reduced to about 0.5% by these means, but when higher purities are specified the membrane area required and the power of the system become excessive. When an oxygen-free product is specified, it is typical to use a hydrogen-based deoxygenation system (hereinafter a "conventional deoxo" system) to treat the retentate (product) of the membrane process. An amount of pure hydrogen is added to the retentate stream which then passes through a catalyst that induces hydrogen to react with the contained oxygen to produce water. A separate dryer system is required to eliminate this water. It is obvious that an excess of hydrogen is required (-2 > 202). This excess of hydrogen remains in the product nitrogen. The combination of a polymeric membrane system with a conventional deoxo purifying system represents the current state of the art to produce high purity nitrogen in small to medium quantities. Nevertheless, an entirely different type of membrane can be made from certain inorganic oxides. These solid electrolyte ion transport membranes are made from inorganic oxides, typified by zirconium stabilized with calcium - or yttrium - and analogous oxides that have a structure of fluorite or perovs ita. At elevated temperatures these materials contain voids of oxygen-oxygen ions. When an electric field is applied through such an oxide membrane, the membrane will transport oxygen through the membrane in the form of oxide ions. Because these materials only allow the penetration of oxygen, they act as a membrane with an infinite selectivity for oxygen. These oxide ceramic membranes are therefore very attractive for use in new air separation processes. Although the potential of these oxide ceramic materials as gas separation membranes is great, there are certain problems in their use. The most obvious difficulty is that all oxide-based ceramic materials exhibit appreciable oxygen ion conductivity only at elevated temperatures. They usually must be operated well above 500 ° C, generally in the range of 500 ° C-1100 ° C. This limitation persists despite much research to find materials that work well at lower temperatures. There are now two types of solid electrolyte ion transport membranes in use: ion conductors that conduct only oxygen ions through the membrane and mixed conductors that conduct ions and electrons through the membrane. As used herein, the terms "solid electrolyte ion conductor", "solid electrolyte ion transport membrane", "ion transport membrane", or simply "solid electrolyte" are used to designate either a material of ionic type or a mixed conductive type material, unless otherwise specified. Solid electrolyte ion conductor technology is described in more detail in Prasad et al., U.S. Patent No. 5,547,494, entitled "Staged Electrolyte Membrane", which is hereby incorporated by reference to more fully describe the state Of art. A solid electrolyte ion transport membrane that exhibits mixed conduction characteristics can carry oxygen when it is subjected to a differential partial pressure of oxygen through the membrane without the need for an applied electric field or external electrodes which would be necessary with the ionic conductors. In an ionic or blended inorganic oxide, oxygen transport occurs due to the presence of oxygen vacancies in the oxide. Oxygen ions kill the vacancies of oxygen ions that are highly mobile in the oxide. Electrons must be supplied (and removed on the other side of an oxide membrane) to make the reaction proceed. For materials that exhibit ionic conductivity only, electrodes must be applied to the opposite surfaces of the oxide membrane and the electronic current is supplied by an external circuit. Prasad et al., US Patent No. 5,557,951, entitled "Process and Apparatus for Recovering Argon from a Cryogenic Air Separation Unit", reveals the extraction of an argon-enriched liquid from a packed argon column, evaporating the liquid enriched in argon to produce steam enriched in argon, and contacting the argon-enriched steam with an ionic membrane of solid electrolyte or mixed conductor. Product grade argon is recovered having an oxygen concentration of less than about 10 ppm. Chen et al., Patent of E.U. , No. No. 34,595 (reissue of U.S. Patent No. 5,035,726), entitled "Process for Removing Oxygen and Nitrogen from Crude Argon," reports the use of electrolytically-driven solid electrolyte membranes for the removal of low levels of oxygen. oxygen from crude argon gas streams. Chen et al., estimates the electrical power needed for several examples of multi-stage processes and also mentions the possibility of using mixed conductor membranes operated by maintaining an oxygen pressure on the feed side. Chen et al. Further teaches that the oxygen present on the permeate side of an electrically enhanced ionic membrane can be either removed as a stream of pure oxygen or mixed with a suitable "sweet" gas such as nitrogen. Mazanec et al., U.S. Patent, No. 5,160,713, entitled "Process for Separating Oxygen from Gas Containing Oxygen Using a Bi-Containing Mixed Metal Oxides Membrane", refers to oxygen separation processes using a bismuth-containing membrane of blended metal oxides which generally stipulates that oxygen separated can be collected for recovery made to react with an oxygen consuming substance. The spent oxygen retentate is apparently discarded. Mazanec et al., U.S. Patent, No. 5,306,411, entitled "Membranes of solid lti-G-xttponents, Components of Electrochemical Reactors, Electrochemical Reactors and Membrane Usage, Components of Reactors, and Reactor for Oxidation Reactions", refers to a number of uses of an electrolyte membrane solid in an electrochemical reactor. It is mentioned that the nitrous oxides and sulphurous oxides in the gases of the ducts or outlet pipes can be converted into nitrogen gas and elemental sulfur, respectively, and that a reactive gas such as a light hydrocarbon gas can be mixed with an inert gas diluent which does not interfere with the desired reaction, although the reason for providing such a mixture is not established. None of the two patents of Mazanec et al., Cited, disclose processes for producing a high purity product of an oxygen-containing stream. OBJECTIVES OF THE INVENTION It is therefore an object of the invention to provide an efficient process for obtaining nitrogen or other high purity inert gas using a hybrid mass oxygen separation system and an ion transport module with a gas stream of purge to reduce energy consumption. It is also an object of the invention to provide an efficient process for making nitrogen or other high purity inert gas using a hybrid non-cryogenic mass oxygen separation system and an ion transport module by recycling the waste stream of the module purge of ion transport to reduce energy consumption. It is a further object of the invention to increase the efficiency of hybrid processes by purging the penetration side of the ion transport membrane with a waste purge, a product purge, or a reactive purge. It is still another object of the invention to improve the efficiency of hybrid processes using a multistage polymer pvsmbrane separation system such as the non-cryogenic mass oxygen separation system. It is still a further object of the invention to improve the efficiency of hybrid processes using multi-stage ion transport membranes as oxygen scavengers. It is still another object of the invention to improve the efficiency of hybrid processes by using a heat exchanger to pair the ambient temperature region of the polymeric membrane system with the high temperature region of the ion transport membrane system.

SUMMARY OF THE INVENTION The invention comprises a process for removing oxygen from a feed gas stream containing elemental oxygen and at least one other gas to produce a retentate gas stream depleted in oxygen. The process involves supplying the feed gas stream to a bulk oxygen separation system to remove oxygen to produce a gas stream of spent product in oxygen and a first residual permeate stream containing oxygen. The gas stream of oxygen depleted crude product is then supplied to a separator that includes a primary ion transport module having a primary ion transport membrane with a retention side and a penetration side, to produce a second stream residual permeate and retentate gas stream exhausted in oxygen. Preferably, a reactive purge gas is then added to react with at least a portion of the oxygen that penetrates through the primary ion transport membrane and purge the permeate side of the primary ion transport membrane, thereby improving the efficiency of the process. In a preferred embodiment of the invention, the separator further comprises an initial ion transport module membrane having a permeate side and a retentate side to which the gas stream of spent oxygen product is supplied to produce a current of retentate gas depleted in initial oxygen and an initial residual permeate stream, the initial ion transport membrane connected in series with the primary ion transport membrane such that the retentate gas stream depleted of initial oxygen is supplied to the primary ion transport membrane. side of the retentate of the primary ion transport membrane. In another preferred embodiment of the invention, at least a portion of at least one of the first permeated waste stream containing oxygen from the bulk oxygen separation system and the residual waste stream from the primary ion transport membrane is recycled. by addition to the feed gas stream. In another preferred embodiment of the invention, the reactive purge gas is in stoichiometric excess to oxygen that penetrates through the ion transport membrane and reacts with substantially all of the oxygen therein to produce a purge stream containing combustion products and a portion of unreacted reactive purge gas, the purge waste stream being used to purge the permeate side of the primary ion transport membrane. In yet another preferred embodiment of the invention, the purge current of the primary ion transport membrane is used to purge the permeate side of the initial ion transport membrane. The invention also comprises a process for removing oxygen from a feed gas stream using a stream of recycled gas comprising at least a portion of at least one stream of gas produced during the process, which is recycled by adding the stream of recycle gas to at least one process gas stream. The invention further comprises a process for removing oxygen from a feed gas stream containing elemental oxygen and at least one other gas to produce a retentate gas stream depleted of oxygen. The process involves supplying the feed gas stream to a first polymeric membrane stage having a retentate side and a permeate side to remove oxygen to produce a first gas stream of spent oxygen product and a first stream residual of permeate containing oxygen. The first gas stream of spent oxygen product is then supplied to a second polymeric membrane stage having a retentate side and a permeate side to remove oxygen to produce a second permeate waste stream and a second product gas stream. raw oxygen depleted, the second stage of polymeric membrane connected in series with the first polymeric membrane stage in such a way that the first gas stream of crude product exhausted in oxygen is supplied to the retentate side of the second polymeric membrane stage. The second gas stream of oxygen depleted crude product is supplied to a separator that includes a primary ion transport module having a primary ion transport membrane with a retentate side and a permeate side, to produce a third stream residual permeate and retentate gas stream exhausted in oxygen. A stream of recycle gas that comprises at least a portion of at least one stream of gas produced during the process is recycled by adding the recycle gas stream to at least one stream of process gas. In a preferred embodiment of the invention, the recycle gas stream comprises at least a portion of at least the first or one of the first residual oxygen-containing permeate streams of the polymeric membrane first stage and the second residual polymeric waste stream. permeate containing oxygen from the second stage of the polymeric membrane. In another preferred embodiment of the invention, the separator further comprises an initial ion transport module having an initial ion transport membrane with a permeate side and a retentate side to which the second stream of raw product gas is supplied. depleted in oxygen to produce a retentate gas stream depleted in initial oxygen and an initial residual permeate stream, the initial ion transport module connected in series with the primary ion transport module such that the gas stream retained oxygen depleted is supplied to the retentate side of the primary ion transport membrane. BRIEF DESCRIPTION OF THE DRAWINGS Other objects, aspects and advantages of the invention will occur to those skilled in the art of the following description of preferred embodiments and the accompanying drawings, in which: Fig. 1 is a schematic diagram of an embodiment of the invention wherein a gas stream of low to high purity nitrogen intermediate product from a bulk oxygen separation system is treated in a solid electrolyte ion transport module where a reactive purge is executed to produce an oxygen-free product; Fig. 2 is a schematic diagram of an embodiment of the invention wherein a two-stage polymer membrane system produces a medium-high purity nitrogen intermediate which is then treated in an energized ion transport membrane module. electrically to produce an oxygen-free product; Fig. 3 is a schematic diagram of an embodiment of the invention similar to Fig. 2 using a pressurized ion transport membrane module wherein a portion of the high purity product is used for a purge stream for the ion transport membrane; Fig. 4 is a schematic diagram of one embodiment of the invention having a two-stage polymer membrane system and a two-stage solid electrolyte ion transport module system in which the final stage of the ion transport module of solid electrolyte employs a product purge and the permeate gas stream from the second polymeric membrane stage is used to purge the first stage of the solid electrolyte ion transport module; Fig. 5 is a schematic diagram of an embodiment of the invention similar to Fig. 4, where a reactive purge is performed in the last stage of the solid electrolyte ion transport module and the exhaust gases are used to purge the first stage of the solid electrolyte ion transport module; Fig. 6 is a schematic diagram of an embodiment of the invention similar to Fig. 5, wherein the reactive purge contains an excess of fuel so that the purge residual stream contains little oxygen but includes some fuel and the products of ccmbustión which is then reacted with a gas containing oxygen in a burner; Fig. 7 is a schematic diagram of an embodiment of the invention similar to Fig. 3 but showing how the ambient temperature region of the polymer membrane separation system can be coupled by a heat exchanger with the high temperature region of the solid electrolyte ion transport module; Fig. 8 is a schematic diagram of an embodiment of the invention similar to Fig. 4 but showing how the ambient temperature region of the polymer membrane separation system can be coupled by a heat exchanger with the high temperature region of the solid electrolyte ion transport module; Ta Fig. 9 is a schematic diagram of one embodiment of the invention showing elements of a heat exchanger and having a solid electrolyte ion transport module system in which the gas stream of the mass oxygen separation system is passed. first through an internal heat exchanger inside the second solid electrolyte ion transport module before being purified by the first stage of the solid electrolyte ion transport module and the second stage of the solid electrolyte ion transport module; Fig. 10 is a schematic diagram of one embodiment of the invention showing elements of the heat exchanger and having a two-stage solid electrolyte ion transport module system wherein the gas stream of the oxygen separation system in The mass is first purified by the first stage of the solid electrolyte ion transport module and is then introduced to the second stage of the solid electrolyte ion transport module by means of a novel reactor design element for further purification; and Fig. 11 is a schematic diagram of an embodiment of the invention showing elements of the heat exchanger and having a two-stage ion transport module system wherein the gas stream of the oxygen separation system in mass is introduced first to the first stage of the ion transport module by means of a novel element of reactor design and is further purified by the second stage of the ion transport module. DESCRIPTION D-_IAI_LADA OF THE INVENTION The invention can be carried out using a solid electrolyte ion transport membrane system, either electrically enhanced or pressure-enhanced, as the separator for removing residual oxygen from a gas stream of spent oxygen product obtained from a mass oxygen separation system after processing an initial feed stream. Since the operation of the two types of solid electrolyte ion transport systems is somewhat different, separate descriptions of mass oxygen separation system / hybrid solid electrolyte ion transport systems are given below. Preferably at least 50% of the elemental oxygen in the initial feed stream is removed by the bulk oxygen separation system. The gas stream fed to the solid electrolyte ion transport portion of the system would have a preferred range of 88-99% nitrogen (more correctly, oxygen-free gas), i.e., 1-12% elemental oxygen; the most preferred range being 93-98% nitrogen, argon or other inert gases (oxygen-free gas), that is, 2-7% elemental oxygen. The solid electrolyte ion transport apparatus is generally operated above 400 ° C, preferably in the range of 400 ° C-12000 ° C, more preferably in the range of 600 ° C-1000 ° C. Due to the need to maintain these high temperatures, the gas stream fed to the solid electrolyte ion transport apparatus must usually be heated. In this invention, the conventional deoxo system and the associated hydrogen and dryer supply systems of the prior art are eliminated. High purity nitrogen can be produced efficiently and economically by combining a mass oxygen separation system, such as a polymer membrane system, with a solid electrolyte ion transport membrane system. The polymer membrane system removes the bulk of the oxygen and also removes almost all of the water vapor and carbon dioxide from the feed gas stream, while the solid electrolyte ion transport membrane system removes the remaining oxygen to make a substantially oxygen-free product, hereinafter referred to as a high purity product. Most gases processed by mass oxygen separation systems will have been separated from their impurities, such as water vapor and carbon dioxide, in the pre-purification stage. It should be noted, however, that a supplemental post-purifier can be used to remove any water produced by the proton conduction from the anode to the cathode and its reaction with oxygen, which is a possibility with some electrolytes and would lead to some Low level contamination of the product. Such a supplemental post-purifier could be a polymer membrane system but is preferably a thermal oscillating absorption system which can take advantage of thermal integration with the solid electrolyte ion transport process at elevated temperature. In this invention, the residual oxygen in the retentate of the polymeric membrane process is removed by an additional "membrane" made of a solid electrolyte ion transport material. Such solid electrolyte ion transport materials can transport oxygen, and only oxygen, by an oxygen ion vacancy mechanism. The separation factor for O? / N2 is therefore infinite. The residual oxygen is removed without injecting any other impurities into the product stream. There is no need for the hydrogen required by the conventional deoxo process, and there is no need for a dryer to remove the water formed by the combustion of hydrogen. Many solid oxides that could serve as solid electrolyte ion transport membranes conduct only oxygen ion vacancies. With such materials, electrodes must be applied to the oxide surfaces and an electrical voltage and current must be applied in order to transport oxygen through the membrane. Other oxides that conduct vacancies of oxygen ions and electrons have been synthesized. With these materials, oxygen can be transported through the membrane by the application of a partial pressure ratio of oxygen through the membrane without the need for electrodes or electrical energy. Any of these solid electrolyte ion transport materials can be used, in accordance with this invention, to remove residual oxygen in the retentate of the polymeric membrane system. As mentioned before, the terms "solid electrolyte ion conductor", "solid electrolyte ion transport membrane", "ion transport membrane", or "solid electrolyte" are used to designate either an ionic type material or a mixed conductive type material unless otherwise specified. The term "nitrogen" as used herein will usually mean gas depleted in oxygen, that is, exhausted in oxygen in relation to the feed gas. Cerno was discussed before, the ion transport membrane allows only the penetration of oxygen. Therefore, the composition of the retentate will depend on the composition of the feed gas. The feed gas will be depleted in oxygen, but will retain nitrogen and any other gases (eg, argon) present in the feed gas. The meaning of the term will be clear to the skilled artisan in the context of the use of the term in light of the invention as described herein. blunt is used here, the term "elemental oxygen" means any oxygen that is not combined with any other element of the Periodic Table. Although typically found in diatomic form, elemental oxygen includes simple oxygen atemos, triatomic ozone, and other forms without combining with other elements.

The term "high purity" refers to a product stream containing less than two percent by volume of unwanted gases. Preferably the product is at least 99.0% pure, more preferably 99.9% pure, and most preferably at least 99.99% pure, wherein pure indicates an absence of unwanted gases. The term "non-cryogenic mass separation system" refers to any gas separation system that does not use a liquid-gas phase change to separate oxygen from one or more other gases, ie does not use distillation, and includes absorption systems and conventional polymer membranes. The terms "pressure swing absorption" or "AOP" refer to systems that use absorption materials that are selective for a gas, typically nitrogen or oxygen, to separate that gas from other gases. Such materials include selective, oxygen-selective AOP materials, which are usually carbon-containing AOP materials and provide nitrogen-selective high pressure nitrogen and low pressure nitrogen, selective, which are typically molecular meshes of zeolite. and provide low pressure nitrogen and high pressure oxygen. If an AOP system is part of the mass separation system, a selective AOP system of ratio is particularly suitable for pressure-driven ion transport systems because such systems provide high pressure nitrogen and low pressure oxygen, which is a significant advantage because the primary driving force for the ion transport membrane is the feed gas pressure. In contrast, the selective AOP systems of ratio and selective AOP systems work equally well for an electrically driven ion transport system or any ion transport system with a reactive purge because the supply gas pressure is not the force primary driver of such ion transport systems. The term "waste stream" as used herein designates a gas stream that is typically discarded but may be used as a "purge stream" to purge the membranes and perform other functions. The term "oxygen-containing waste stream" as used herein in relation to the ion transport separator refers to a permeated or penetrated stream in which some or all of the oxygen leaving the ion transport membrane may have been consumed For example, when a stream of reactive purge gas is used to purge the permeate side (anode) of the ion transport membrane, the reactive gas reacts with the oxygen penetrating through the ion transport membrane at the surface of the ion. the membrane of ion transport. Therefore, with such a reactive purge stream, a mass oxygen gas stream is not formed in the ion transport module nor does an oxygen gas stream exit the ion transport module. If an inert purge current is used, the permeate gas stream leaving the ion transport module will be diluted by the inert purge stream. In the absence of a purge stream, the permeate gas stream that carries oxygen away from the ion transport membrane is pure oxygen, and both the feed or retentate streams must be at high pressure (or the permeate stream under pressure). very low) to create a driving force for oxygen transport. While such an unpurged membrane is attractive for the removal of larger amounts of oxygen from inert gas streams, oxygen recovery is limited by pressures that can be applied. Even so, the degree of purification that can be obtained is limited. The term "residual permeate stream" includes waste streams, waste streams containing oxygen, and other emissions from the permeate zone which can be used as purge streams according to the present invention. It should be noted that gas streams that are described as oxygen enriched contain a higher percentage of oxygen than the feed gas stream and those described as depleted in oxygen contain a lower percentage of oxygen than the feed gas stream. A) Yes, if the air (containing 21% oxygen) were the feed gas stream, an oxygen enriched gas stream would contain more than 21% oxygen. Thus, the term enriched in nitrogen is synonymous with oxygen depleted and the term depleted in nitrogen is synonymous with the term enriched in oxygen. The invention will now be described in detail with reference to the figures in which like reference numerals are used to indicate similar elements. One embodiment of the invention is illustrated by the schematic process diagram shown in Fig. 1. In this embodiment, a gas stream 82 of raw nitrogen intermediate or oxygen depleted product is generated by the bulk oxygen system 11 a starting from the feed gas stream 8. The intermediate gas stream 82 is treated in the ion transport module 31 where a reactive gas purge can be performed to produce the retained gas stream 89 of high purity. Many of the embodiments of the invention use a reactive purge gas to purge the permeate side of the solid electrolyte ion transport membrane and, in some cases, the purge gas can be recycled or, if used in excess, the reactant gas of unreacted purge and a gas stream containing oxygen can be introduced and burned in a burner to remove unreacted fuel gas and carbon monoxide before discharging. During operation, the feed gas stream 8 is compressed by the pulper 51, cooled by the cooler 74, and partially separated by the bulk oxygen separation system 11 which produces the gas stream 82 and the waste stream 79, which is discarded. The gas stream 82 is divided into two gas streams of desired proportions in order to regulate the temperature of the feed gas stream 85 in such a way that the ion transport module 31 is maintained within a desired temperature range for the heat generated by the reaction of oxygen in the permeated zone 34 with the reactant gas stream 61. For example, if the gas stream 82 contained 5% oxygen by volume, the volume fraction of the first gas stream 84 could be 0.3 (ie, about 30% of the volume of the gas stream 82) and a second gas stream 83 would be 0.7 (ie, about 70% of the volume of the gas stream 82) to maintain the temperature of the ion transport module 31 in a desired temperature range of 800 ° C-1050 ° C. If, however, the gas stream 82 contained only 2% oxygen by volume, the volume fraction of the first gas stream 84 could be 0.7 and the volume fraction of the second gas stream 83 would be 0.3. It should be noted that these fractions vary depending on the operating temperature of the ion transport membrane. The first gas stream 84 is heated by the product gas stream 89 using the heat exchanger 21 while the second gas stream 83 is not heated. The first gas stream 84 and the second gas stream 83 are combined in the feed gas stream 85 and introduced to the ion transport module 31 where the mixed conductor ion transport membrane 22 removes oxygen from the stream of feed gas 85. All or part of the oxygen transported through the ion transport membrane 22 reacts with the fuel contained in the reactive purge gas 61 and produces a low partial pressure of oxygen at the anode, thereby creating a high oxygen partial pressure ratio through the ion transport membrane 22 as a driving force. As a result, high oxygen flows can be obtained, the membrane areas can be minimized, and very high product purities can be obtained. The product gas stream 89 is cooled, if necessary, to a desired temperature by the cooler 72. The purge product gas stream 88 can be withdrawn from the product gas stream 89 to purge the permeate side of the transport membrane. of ions 22. In general, the volume fraction of a product gas stream used for such product purge would be 5-30% by volume or, more preferably, 10-20% by volume. Because the ion transport system is typically operated at elevated temperature (approximately 800 ° C), an ignition or ignition system 41 is provided to raise the temperature of the ion transport membrane 22 to the desired range. The starter system 41 comprises a heater 43 for the air stream 44, the reactant gas stream 45 (e.g., methane), and a catalytic monolith 42 which causes the reactant gas and the heated air to react and produce a gas stream. hot exhaust 81 which is used to purge the permeate side of the ion transport membrane 22 and thus heat the ion transport membrane 22 to the desired operating temperature. After the ion transport membrane 22 reaches the desired operating temperature and the regular purification operation begins, the use of the starter system 41 is discontinued until needed again. Then the temperature of the ion transport membrane 22 is normally maintained in the desired range during the course of the operation. The arrangements of the reactive purge are described in "Reactive Purge for Gas Separation by Solid Electrolyte Membrane", E.U. Series No. 08 / 567,699, filed on December 5, 1995 EP Publ. No. 778,069, and incorporated herein by reference. Preferred configurations for ion transport modules using a reactive purge are described in "Solid Electrolyte Ionic Conductor Reactor Design", E.U. Series No. 08 / 848,204 filed on April 29, 1997 and also incorporated herein by reference. Both applications are recognized with the present application. "Electrically Powered Ion Transport Membrane Systems" Another embodiment of the invention is illustrated by the schematic process diagram shown in Fig. 2. For simplicity, this mode, unlike Fig. 1, does not show the heaters, chillers, and heat exchange equipment that would be used in the actual operation of the invention. During operation, the supply gas stream 8 is compressed by the compressor 51 and is fed to the first stage of the polymeric membrane 12 whose polymer membrane 15 removes oxygen, water vapor, and carbon dioxide to produce an initial current. of oxygen-depleted crude product gas and a waste stream 93. The initial gas stream 86 is fed to the second stage 13 of the polymer membrane whose polymer membrane 16 removes oxygen, steam, water vapor, and carbon dioxide to produce the gas stream 85 and the waste residual waste stream 92. The gas stream 85 is introduced to the ion transport module 31 where the ion transport membrane 23 energized by an external power source 62 removes oxygen from the feed gas stream 82 to produce the gas stream 89 of high purity nitrogen and the waste gas stream 91. The waste gas stream 91 of the ion transport module 31 and, optionally, the waste stream 92 of the second polymeric membrane stage 13 are combined as the recycle gas stream 95 and added to the feed gas stream 8. Alternatively, or in addition, the reactive gas stream 61 may be used to purge the permeate side of the ion transport membrane 23. Air may also be used, the crude product stream 85, or the gas stream 91 to purge the permeate side of the membrane. ion transport 23. When a relatively large voltage is applied, the partial pressure of the product oxygen can be reduced to extremely low values (less than 1 ppb, for example). The electric current required depends on the oxygen flow, or of the ratio of elimination of the oxygen contained in the retentate. Thus, the electrical energy to operate the ion transport process will be proportionately less as the oxygen content of the intermediate current is decreased and as the permissible concentration of oxygen in the product is increased. As illustrated in Fig. 2, the energy requirement can be reduced by using a purge gas stream or by using the reactant gas stream 61 to purge the permeate side of the 23 ion transport membrane. It should be noted that even if the purge stream for the ion transport module 31 contains oxygen, it will usually be less concentrated than pure oxygen and will be effective in reducing the partial pressure of oxygen on the permeate side of the ion transport membrane 23. The polymer membranes which are suitable for air separation by the selective penetration of oxygen will also remove water vapor and carbon dioxide. Since the ion transport process does not introduce impurities into the nitrogen stream, the product will be of higher purity than the product of a conventional hybrid-deoxo hybrid system. The concentration of oxygen in the intermediate retained gas stream 82 of the polymer membrane system is a critical variable in the design and optimization of the overall process. Polymer membrane systems can typically produce nitrogen purities of 90% to 99.5%, depending on the number of membrane steps employed. With a single membrane step the low purity intermediate that would be introduced into the ion transport module 31 would probably not exceed about 99% (ie, about 1% oxygen). For efficient production of high purity nitrogen it is likely that that concentration of intermediate would be quite low (approximately 1% or less). Thus, it is preferable to use a multi-stage polymer membrane system. For example, a two-stage purification system is illustrated in Fig. 2. The nitrogen stream 82 of the polymer membrane steps will typically contain 0.5% to 3.0% oxygen impurity. The permeate gas stream 92 of the polymeric membrane second stage 13 is rich in nitrogen typically compared to air and it is desirable to recycle this gas stream 92 to the compressor 51 as a stream of recycled gas 97. In another embodiment, some or all of the residual permeate stream 92 is directed to purge the ion transport membrane 23 as purge stream 97a, also shown as dotted line. In general, it is desirable to recycle a gas stream through the system when the oxygen concentration of the gas stream is less than that of the air, that is, the gas stream contains less than 21 volume% oxygen. A portion of the permeate from the second stage can also be used - purge current 95 for the permeate side of the ion transport membrane 23, thus reducing the voltage and operating energy of the module. In general, electrically driven ion transport membrane systems will be employed possibly if the application is small and where the desired purity of the nitrogen is high. In such a system, the amount of oxygen in the feed gas stream 85 to the ion transport module 31 will preferably be less than 2% due to the large amount of electrical energy required to transport the oxygen through the transport membrane of the carrier. ions 23. Using the waste stream 92 of the second polymeric membrane stage 13 as purge gas stream 95 for the ion transport membrane 23 will result in a need to provide an additional recovery heat exchanger. An alternative option would be to use a portion of the product stream as a purge for the ion transport membrane 23, which will similarly lower the partial pressure of oxygen on the permeate side of the ion transport membrane 23 and thereby lower the requirements of energy for the ion transport module. This alternative would avoid the need for an additional heat exchanger but, consuming the product gas stream, the practical performance of the system would be reduced. It would be useful under any option to recycle the purge waste stream 91 of the ion transport module again through the feed gas stream 8 since the nitrogen content is generally higher than that of the feed gas stream 8. , which is usually air. It is obvious that these principles can be extended to the hybrid processes of ion transport membrane / polymer membrane where the polymer membrane system comprises three (or even more) stages. As explained above, it should also be noted that the hybrid systems of the invention generally require heaters, coolers and heat exchange equipment that are not shown in the embodiments shown in Figs. 2-6. In smaller systems that would possibly employ electrically driven ion transport systems such as the one shown in Fig. 2, electric heaters are used to increase the T's for the benefit of the recovery heat exchangers and the system derived from the use of these electric heaters to enable a simple start of the ion transport membrane system by raising the temperature of the feed gas without additional equipment. "Pressure Driven Ion Transport Membrane Systems" Complex oxides can be made that exhibit both ionic and electronic conductivity. A membrane of such a mixed conductor can carry oxygen when subjected to a differential partial pressure of oxygen, without the need for an applied electric field. For such materials, the counter-current flow of oxygen vacancies is carried by an internal flow of electrons, rather than through an external circuit. No electrodes are required and the entire transport is moved by the partial pressure ratio of the retentate with the permeate side gas streams. The internally developed Nernst potential drives the flow of oxygen vacancies against the ionic resistance of the electrolyte.

Another embodiment of the invention is illustrated by the schematic process diagram shown in Fig. 3 which shows how an ion transport membrane of mixed conductor can be used in an ion transport module to eliminate 0.5% -3.0% of oxygen in the retentate of a two-stage polymer membrane system. As in Fig. 2, this embodiment does not show the heaters, coolers and heat exchange equipment that would be used in the actual operation of the invention. During operation, the supply gas stream 8 is compressed by the compressor 51 and is fed to the first polymeric membrane stage 12 whose polymeric membrane 15 removes oxygen, water vapor and carbon dioxide to produce the initial gas stream. and the waste stream 93. The initial gas stream 86 is fed to the second polymeric membrane stage 13 whose polymer membrane 16 removes oxygen, water vapor and carbon dioxide to produce the gas stream 85 of oxygen depleted crude product. and the waste stream 92. The gas stream 85 is introduced to the ion transport module 31 wherein the mixed conductor ion transport membrane 22 removes oxygen from the feed gas stream 85 to produce the gas stream. high purity nitrogen 89 and waste gas stream 91. Waste stream 92 from second stage 13 polymer membrane can be used as recycled gas stream 97 and added to the feed gas stream 8. Alternatively, or in addition, a portion of the stream of high purity nitrogen product 89 can be used as the product purge gas stream 88 to purge the side permeate of the ion transport membrane 22. The waste gas stream 91 of the ion transport module 31 contains oxygen and nitrogen and can be recycled to the compressor 51 together with the recycle stream 97 to form a combined recycle stream 98 which is added to the feed gas stream 8 or, if the waste stream 91 is sufficiently rich in nitrogen, it may be desirable to separately compress some or all of this waste stream 91 as intermediate recycle stream 99, shown in dotted lines, using a optional compressor 52 and injecting it into feed gas stream 86 of second stage 13 of polymeric membrane. As stated before, it is generally desirable to recycle a gas stream through the system when the oxygen concentration of the gas stream is less than that of the air. In general, a purge using the permeate gas from a polymer membrane stage would not have a sufficiently low oxygen concentration to work effectively with a pressurized ion transport membrane. The volume fraction of a product gas stream used for such a product purge would be 5-30% by volume or, more preferably, 10-20% by volume. The oxygen content on the permeate side of the ion transport membrane must be very low in order to maintain the partial pressure driving force for oxygen flow through the ion transport membrane. Pressure driven systems without a reactive purge are mainly dependent on purging with a portion of the high purity product to produce the driving force for oxygen transport. The amount of purge gas that is required will depend on the pressure ratio across the ion transport membrane. Such pressurized systems would probably not be employed where ultra-high purity nitrogen (less than 5 ppm oxygen) is desired. The purge stream leaving the permeate side of the ion transport membrane can be fed to the suction of the compressor to improve the recovery of nitrogen in the polymer membrane system. With a single-stage ion transport membrane system it is possible that the system feed will be limited to oxygen concentrations of less than 2% to 5%. With the use of a second ion transport stage, the oxygen concentration of the system feeding can be increased. For all pressurized ion transport systems without reactive purge, external heat must be added to the high temperature end to maintain reasonable UAs in the recovery heat exchangers. In contrast, a pressurized system with a reactive purge uses a reactive purge gas to react with the permeating oxygen to create a very low partial pressure of oxygen on the permeate side of the ion transport membrane and therefore a force very high booster for the transport of oxygen and the ability to achieve very low oxygen concentrations in the product gas retained. The best product economy will possibly be achieved with a mass oxygen separation system which produces a nitrogen product containing 4% to 7% oxygen that is fed to the deoxo ion transport system which removes the remaining oxygen to a concentration of less than 5 ppm in the high purity nitrogen product stream. The purge stream of the ion transport system can be recycled to the suction of the compressor for the feed gas since the purge stream would then contain little or no oxygen. In such a case, the mass oxygen separation system will have to remove additional carbon dioxide and water vapor from the reaction products in the gas stream. Fig. 4 illustrates a hybrid process comprising a two-stage polymer membrane system and a two-stage ion transport system. In this example, the final stage of ion transport 32 employs a product purge gas stream 88, and at least a portion of the permeate gas stream 92 of the second polymeric membrane stage 13 is preferably directed as a stream of gas 100, shown in dashed lines, for purging the first ion transport stage 31 as gas stream 95. The purge waste gas stream 94 of the final ion transport stage 32 can be recycled to the compressor 51 as current of recycle gas 98 which is successively formed of streams 94 and 106 in this mode. Alternatively, at least a portion of the stream 98 can be compressed by the optional compressor 52 and be injected into the interstage feed stream 86 as gas stream 99 or at least a portion of the stream 106 can be used to purging the second polymer membrane 16 as gas stream 53, depending on the concentration of oxygen. During operation, the supply gas stream 8 is compressed by the compressor 51 and is fed to the first polymeric membrane stage 12 whose polymeric membrane 15 removes oxygen, water vapor and carbon dioxide to produce the initial gas stream. and the waste stream 93. The initial gas stream 86 is fed to the second polymeric membrane passage 13 whose polymer membrane 16 removes oxygen, water vapor and carbon dioxide to produce the gas stream of crude product 85 depleted in oxygen and the permeated waste stream containing oxygen 92. The gas stream 85 is introduced to the first ion transport module 31 to remove oxygen from the gas stream 85 to produce the high purity nitrogen gas stream 89 and the permeate waste gas stream. 91. Optionally, a portion of the gas stream 89 can be directed through a valve 108, shown in stitch line, and use FIG. 3 is a view of the first embodiment of the ion transport membrane of the first ion transport module 31, with the purge current 95 in this mode. The high purity nitrogen gas stream 89 is then introduced to the second ion transport module 32 to remove more oxygen from the high purity nitrogen gas stream 89 to produce the high purity nitrogen gas stream., which is preferably passed through a heat exchanger and recovered as the product, and the permeate waste gas stream 94. A portion of the high purity nitrogen gas stream 87 is used as the product purge gas stream. 88 to purge the permeate side of the second ion transport module 32 and form the waste gas stream 94. The optional gas stream 100, which accrues some or all of the permeate waste stream 92, can be added to the gas stream. residual 94 to form the gas stream 95. The gas stream 95, to which the optional gas stream 100 can be attached, is used as a purge gas stream to purge the pee-pee side of the first transport module 31 of ion and form the permeate waste gas stream 91. The waste gas stream 91 can be combined with the gas stream 94 to make the gas stream 106. The gas stream 106 can optionally be used for pu The second polymer membrane 16 is connected to the gas stream 53. The gas stream 106 is combined with the waste stream 92 to make the gas stream 98, which is added to the supply gas stream 8 and recycled to the compressor 51. or, optionally, it can be directed as the gas stream 99 to be compressed by the optional compressor 52 and injected to the inter-stage feed stream 86, depending on the oxygen concentration. The purge residual stream 94 can also be used to purge the second stage 13 of the polymer membrane without combining with the waste stream 91. The oxygen content of the high purity nitrogen product of the transport stage (s) of ions can be very low, fluctuating between 10 ppm and less than 1 ppb. The hybrid membrane / ion transport processes that have been described do not require hydrogen or other additional gases. If an economical source of fuel such as methane is available, a different mode of operation using a reactive purge is preferred. One form of this reactive purge precess is illustrated in Fig. 5. The fuel gas stream 61 can be used to purge the permeate side of the ion transport membrane of the ion transport module 32. The fuel gas stream 61 will react with the oxygen penetrating through the ion transport membrane of the ion transport module 32, thereby reducing the partial pressure of oxygen to an extremely low value. This maintains the driving force for oxygen flow through the ion transport pvambrane of the ion transport module 32. In this embodiment of the invention, the amount of fuel used in the purge stream is less than that required for react with all the oxygen to be removed (an equivalent ratio less than 1.0). In Fig. 5, all fuel is burned in the final ion transport module 32. The exhaust gas stream 94 is then used to purge the first stage of the ion transport module 31 and Fig. 5 represents these two stages of ion transport module 32 and 31 as separate units. It is apparent, however, that these same operations could be carried out in a single stage of ion transport. The final purge residual stream 91 contains some oxygen and all products of combustion. It is desirable to recycle this residual stream 91 from the current 98 to the compressor 51 and then to the polymeric membrane system or stream 99 to the optional processor 52 and then to the intermediate stage supply stream 86. In any case, the polymer membrane system It can efficiently remove water vapor and carbon dioxide, thus rejecting these products from the combustion of the nitrogen stream. In yet another embodiment, the permeate gas stream 91 is directed as the waste stream 102, shown in dotted lines., and thermal energy can be captured from that. Since the combustion process is exothermic, excess heat can be useful to raise the temperature of the ion transport system, which should usually operate above 600 ° C. Much of this heat is produced in the last stage of ion transport of Fig. 5 and the temperature rise could become excessive as long as the feed gas stream is introduced at a temperature low enough to act as a temperature well. Other streams are generated and directed as described elsewhere in this application. For example, a portion of the raw product stream 85 can be directed to purge the permeate side of the membrane 16 and then be recycled via the streams 92, 97 and 98 to meet the feed stream 8. Another way of using a Reactive purge is illustrated in Fig.6. In this case, an excess of fuel is used (an equivalence ratio greater than 1.0). The purge 94 waste gas stream will contain little oxygen but will include some fuel and combustion products, such as carbon monoxide, carbon dioxide, hydrogen, water vapor and methane. This waste gas stream 94 is then reacted with the air stream 90 (or other oxygen-containing gas) in the burner 73. The heat released during combustion can be used for several purposes, including preheating the feed gas for the ion transport process, steam generation to produce additional "inert" purge gas or to heat the high purity, high pressure nitrogen before expansion through a turbine to produce energy. As before, the burnt gas stream 96, after cooling, would be recycled to the polymer membrane system, where the combustion products would be removed from the retained nitrogen stream. Since the polymer membrane process and the ion transport process operate at widely different temperatures, many additional physical elements such as inter-system and inter-stage heat exchangers, inter-coolers, heaters, etc., are required in the practice of the invention that are not shown in drawings 2-6. Fig. 7 is a schematic diagram, however, of an embodiment of the invention similar to Fig. 3 but showing how the ambient temperature region 14 of the polymer membrane separation system can be matched by the heat exchanger 21 with the high temperature region 33 of the ion transport module 31. In addition, the heater 71 is provided to raise the temperature of the feed gas stream 85 entering the ion transport module 31. Among other apparent advantages in this embodiment, the heat exchanger 21 improves the energy efficiency of the process as a whole. Such components and their operation are well known in the art and practice of gas separation and gas processing and their proper use in the present invention will be understood by those skilled in the art. Yet another embodiment of the invention is illustrated by the schematic process diagram shown in Fig. 8. This embodiment shows heaters, coolers and heat exchange equipment that could be used in the actual operation of the invention. During operation, the feed stream 8 is compressed by the compressor 51, cooled by the cooler 74, and is fed to the first polymeric membrane stage 12 whose polymer membrane 15 removes oxygen, water vapor and carbon dioxide to produce the oxygen product gas stream 86 depleted in oxygen and waste stream 93. The initial oxygen depleted gas stream 86 is fed to the second stage 13 of polymer membrane whose polymer membrane 16 removes oxygen, water vapor and carbon dioxide to produce the oxygen product gas stream 85 depleted in oxygen and the waste gas stream 92. The waste stream 92 is divided into the gas stream 95 and the gas stream 97. The gas stream 95 is passed to through the heat exchanger 21 and the heater 75 and added to the waste gas stream of the second ion transport module 32 to form the gas stream 94. The gas stream 85 is passed through the heat exchanger 21 and the heater 71 and is introduced to the first ion transport module 31 to remove oxygen from the gas stream 85 to produce the high purity nitrogen gas stream 89 and the waste gas stream 91. The high purity nitrogen gas stream 89 it is then introduced to the second ion transport module 32 to remove more oxygen from the high purity nitrogen gas stream to produce the high purity nitrogen gas stream., which is passed through the ii-heat exchanger 21 and recovered as the product and the waste gas stream 94. A portion of the high purity nitrogen gas stream 87 is used as the product purge gas stream. to purge the permeate side of the second ion transport module 32 and form the waste gas stream 94. The waste gas stream 94 is used as a purge gas stream to purge the permeate side of the first ion transport module 31. and forming the waste gas stream 91 which is passed through the heat exchanger 21 and combined with the gas stream 97 to form the gas stream 98 which is added to the feed gas stream 8. Another embodiment of the invention is illustrated by the schematic process diagram shown in Fig. 9. This embodiment shows the coolers and heat exchange equipment that are used in an implementation of the invention. During operation, the feed gas stream 8 is compressed by the compressor 51, cooled by the cooler 74 and fed to the first polymeric membrane stage 11 whose polymeric membrane 15 removes oxygen, water vapor and carbon dioxide to produce the initial crude product gas stream 82 depleted in oxygen and the waste stream 79. The gas stream 82 is passed through the heat exchanger 21 to supply the heated gas stream 85 which is passed through the heat exchanger. heat 24 within the second ion transport module 32 to form the gas stream 78. The heat exchanger 24 utilizes the heat capacity of the feed stream 78 of the ion transport module to absorb the heat of reaction without excessive rise of heat. temperature. The gas stream 78 is introduced to the first ion transport module 31 to remove oxygen from the gas stream 85 to produce the high purity nitrogen gas stream 89 and the waste waste stream 91. The high nitrogen gas stream purity 89 is then introduced to the second ion transport module 32 to remove additional oxygen from the high purity nitrogen gas stream 89 to produce the high purity nitrogen gas stream 87, which is passed through the heat exchanger 21. and recovered the product, and the waste gas stream 94. A portion of the high purity nitrogen gas stream 87 is used as a diluent of the reactive purge gas stream 80 to purge the permeate side of the second module 32 of transport of ions and form the waste gas stream 94. This waste gas stream 94 of the second ion transport module 32 is used as a gas stream of purge to purge the permeate side of the ion transport membrane of the first ion transport module 31 and form the waste gas stream 91 which is passed through the heat exchanger 21. The reactant gas stream 61 is used for purging the permeate side of the ion transport membrane of the second ion transport module 32. A different embodiment of the invention is illustrated by the schematic process diagram shown in FIG. 10. This embodiment shows the coolers and heat exchange equipment that could be used in the actual operation of the invention. During operation, the feed gas stream 8 is compressed by the compressor 51, cooled by the cooler 74 and is fed to the bulk oxygen separation system 11 to produce the initial gas stream of spent oxygen product 82 and the waste stream 79. The initial gas stream 82 depleted in oxygen is passed through the heat exchanger 21 to supply the heated gas stream 85 which is introduced to the first ion transport module 31 to remove oxygen from the stream of gas 85 to produce the high purity nitrogen gas stream 89 and the waste gas stream 91. The high purity nitrogen gas stream 89 is passed through the heat exchanger 21 and introduced to the second ion transport module 32. by designing internal reactor 54 or other heat transfer means to remove additional oxygen from the high purity nitrogen stream 89, which is passed through the heat exchanger 21 and recovered as the product, and the waste gas stream 94. The internal reactor pattern 54 with heat transfer means is the subject of the co-pending patent application. USA Series No. 08 / 848,204, by Prasad et al., Entitled "Solid Electrolyte Ionic Conductor Reactor Design", which was filed on April 29, 1997, and is incorporated herein by reference to describe and illustrate more completely the claimed invention. This internal reactor design 54 uses an ion transport membrane to heat the gas stream fed thereto and thus prepares the gas stream for the second ion transport module 32 to remove any residual oxygen.

A portion of the high purity nitrogen gas stream 87 is used as the product purge gas 80 stream to purge the permeate side of the ion transport membrane from the second ion transport node 32 and form the waste gas stream. 94. This waste gas stream 94 of the second ion transport module 32 is used as a purge gas stream to purge the permeate side of the ion transport membrane of the first ion transport module 31 and form the current of residual gas 91 which is passed through the heat exchanger 21. The reactant gas stream 61 combined or diluted by the gas stream 86 is used to purge the. permeate side of the ion transport membrane of the second ion transport module 32 and produces the waste gas stream 94. The temperature of the high purity nitrogen gas stream 89 leaving the heat exchanger 21 is controlled to ensure that the gas stream has sufficient heat capacity to absorb the heat of reaction generated in the second ion transport module 32, thus limiting the temperature rise in the ion transport membrane. Another embodiment of the invention is illustrated by the schematic process diagram shown in FIG. 11. This embodiment shows the coolers and heat exchange equipment that are optionally used in the actual operation of the invention. In this arrangement, the first ion transport module 31 removes most of the oxygen content using a reactive purge and also provides the energy needed to raise the feed gas stream 85 to the operating temperature of the transport membrane of ions. The second ion transport module 32 removes residual oxygen using a purge gas stream 103 of product and combustion product. The advantages are: (1) that the first ion transport module 31 can operate as a burner heater with a relatively simple pipe arrangement and (2) that the arrangement avoids excessively low partial oxygen pressures at the anode of any of the ion transport membranes. Very low partial pressures of oxygen at the anode can be generated in the case of a reducing environment at the anode and a partial low oxygen pressure at the cathode and can lead to reductions in the life of the solid electrolyte membrane material. If the residual oxygen that has to be removed in the second ion transport module 32 is kept sparse, the cost penalties due to the extra area in the second ion transport module 32 due to a low oxygen partial pressure driving force , they can be minimized. The option of using the reaction products as purge gas stream 103 of the first ion transport module 31 to purge the permeate side of the ion transport membrane of the second ion transport module 32 would reduce the need for purge product and, therefore, leads to a greater nitrogen recovery. It is important that all oxygen in the purge gas stream 103 has been consumed before the current is introduced to the second ion transport module 32. Practically, this requires that the reaction in the first ion transport module 31 must be carried out enriched in fuel, taking away the aforementioned reduction wear of material.

During operation, the feed gas stream 8 is cured by the compressor 51, cooled by the cooler 74 and fed to the ground oxygen separation system 11 to produce the initial gas stream 82 and the waste stream 79. The gas stream 82 is passed through the heat exchanger 21 to provide the hot gas stream 85 which is introduced into the first ion transport module 31 with internal reactor design 54 or other heat transfer means to eliminate oxygen from the gas stream 85 to produce the high purity nitrogen gas stream 89 and the waste gas stream 91. As mentioned above with reference to FIG. 10, the internal reactor design 54 is the subject of the US patent application. copendiente Series No. 08 / 848,204, which was previously incorporated by reference. The high purity nitrogen gas stream 89 is then introduced to the second ion transport module 32 to remove more oxygen from the high purity nitrogen gas stream 89 to produce the high purity nitrogen gas stream 87, which is passed through. through the heat exchanger 21 and recovered as the product, and the waste gas stream 94. A portion of the high purity nitrogen gas stream 87 is used as the product purge gas stream 80 to purge the permeate side of the product. the ion transport membrane of the second ion transport module 32 and form the waste gas stream 94 which is passed through the heat exchanger 21. The reactant gas stream 61 is used to purge the permeate side of the ion transport membrane of the first ion transport module 31 and combine with the waste gas stream 91 which is passed through the heat exchanger 21. Another possibility would be to use the residual gas stream 103 to purge the permeate side of the ion transport membrane of the second ion transport module 32 and combine with the waste gas stream 94 which is passed through the heat exchanger 21. Specific aspects of the invention are shown in one or more of the drawings for convenience only, since each aspect can be combined with other aspects according to the invention. In addition, various changes and modifications can be made to the given examples without departing from the spirit of the invention. Such modifications may include the use of oscillating and thermal-oscillating pressure absorption beds or other mass oxygen separation methods to provide the function of the polymer membranes discussed above. Alternative modalities will be recognized by those skilled in the art and are intended to be included within the scope of the claims.

Claims (10)

1. RS-IVINDICATIONS 1. A process for removing oxygen from a stream of feed gas containing elemental oxygen and at least one other gas to produce a retentate gas stream depleted in oxygen, the process comprising: supplying the feed gas stream to a mass oxygen separation system for removing oxygen to produce a gas stream of spent product exhausted in oxygen and a first permeate waste stream; supplying the gas stream of spent oxygen product to a separator including a primary ion transport module having a primary ion transport membrane with a retentate side and a permeate side, to produce a second permeate waste stream and the spent gas stream depleted in oxygen; and adding a reactive purge gas to react with a portion of the oxygen that penetrates through the primary ion transport membrane and purge the permeate side of the primary ion transport membrane, thereby improving the efficiency of the process.
2. 2. The process according to claim 1, wherein the separator further comprises an initial ion transport module having an initial ion transport membrane, the initial ion transport membrane having a permeate side and a retentate side. to which the gas stream of spent oxygen product is supplied to produce an initial stream of oxygen-depleted retained gas and an initial permeate residual current, the initial ion transport membrane connected in series with the primary ion transport membrane so that the initial stream of retained gas depleted in oxygen is supplied to the retentate side of the primary ion transport membrane.
3. 3. The process according to claim 2 wherein the second permeate residual stream of the primary ion transport membrane is used to purge the permeate side of the initial ion transport membrane.
4. The process according to claim 1, wherein at least a portion of at least one of the first permeated waste streams of the mass oxygen separation system and the second permeate waste stream of the primary ion transport membrane It is recycled by addition to the feed gas stream.
5. 5. The process according to claim 1, wherein the reactive purge gas is in stoichiometric excess to the oxygen that penetrates through the ion transport membrane and reacts with all the substantial oxygen therein to produce a permeate residual current of purge containing combustion products and a portion of unreacted reactive purge gas.
6. The process according to claim 5, wherein at least a portion of the purge permeate waste stream and an oxygen-containing gas stream are introduced to a burner and burned there to generate heat energy.
7. 7. A process for removing oxygen from a stream of feed gas containing elemental oxygen and at least one other gas to produce a retentate gas stream depleted in oxygen, the process comprising: supplying the feed gas stream to a feed gas system. oxygen separation in non-cryogenic mass to remove oxygen to produce a gas stream of crude product depleted in oxygen and a first permeate residual stream containing oxygen; supplying the gas stream of spent oxygen product to a separator including a primary ion transport module having a primary ion transport membrane with a retentate side and a permeate side, to produce a second permeate waste stream and the gas stream retained exhausted in oxygen; and recycling a recycle gas stream comprising at least a portion of at least one gas stream produced during the process, adding the recycle gas stream to at least one process gas stream.
8. 8. The process according to claim 7, wherein the separator further comprises a membrane of initial ion transport modulus, the initial membrane of ion transport having a permeate side and a retentate side to which the current of the ion is supplied. Oxygen-depleted crude product gas to produce an initial stream of oxygen-depleted retained gas and a permeated residual initial stream, the initial ion transport membrane connected in series with the primary ion transport membrane so that the initial ion transport Retained gas depleted in oxygen is supplied to the retentate side of the primary ion transport membrane.
9. 9. The process according to claim 7, wherein the primary ion transport membrane is an electrically driven ion transport membrane and at least a portion of the first oxygen-containing permeate waste stream of the mass oxygen separation system is not -Cryogenic is used to purge the permeate side of the primary ion transport membrane. The process according to claim 9, wherein the recycle gas stream comprises the purge stream of the primary ion transport membrane and is recycled by addition to the feed gas stream.