MXPA99005118A - Process that integrates a cell of fuel of solid oxide and a reactor of io transportation - Google Patents

Abstract

An integrated system that uses a solid oxide fuel cell and at least one ion transport reactor to generate electric power and a product gas to supply a gas containing oxygen, usually air, to a first side of the cathode of the cell of solid oxide fuel and supply a gaseous fuel to a first side of the anode. Oxygen ions are transported through a membrane in the fuel cell to the first side of the anode and react exothermically with the gaseous fuel to generate electrical energy and heat. The heat and oxygen transport produces a higher temperature gaseous retentate stream with reduced oxygen content leaving the cathode side of the solid oxide fuel cell that is supplied to a first ion transport reactor where a substantial portion of the Residual oxygen is transported through an oxygen selective ion transport membrane. After a gas stream of production is recovered

Description

PROCESS THAT INTEGRATES A CELL OF OXIDE FUEL SOLID AND AN ION TRANSPORTATION REACTOR FIELD OF THE INVENTION This invention relates to a process for the cogeneration of energy and at least one product gas. More particularly, the process integrates a solid oxide fuel cell and an ion transport reactor. BACKGROUND OF THE INVENTION Electric power is traditionally generated by a thermodynamic process. Heat, for example, can be generated by burning oil in a heater to overheat pressurized water. The superheated water expands into pressurized steam that mechanically rotates a turbine. The rotation of the reactor fins of an electric generator rotor connected to the turbine through an appropriate magnetic field generates electrical energy. The conventional electric power generation uses a thermal / mechanical process, the efficiency of which is limited by the Carnot cycle. The Carnot cycle is that, even under ideal conditions, a heat engine can not convert all the heat energy supplied to it into mechanical energy and, therefore, a significant portion of heat energy is rejected. In the Carnot cycle. A motor accepts heat energy from a high temperature source, converts part of the heat energy into mechanical work and rejects the rest of the heat energy to a low temperature heat vessel. The heat energy rejected causes a loss in efficiency. A different process for generating electricity uses a solid oxide fuel cell. The electrical energy results from the direct conversion of the released energy as a chemical reaction in electrical energy, instead of a thermal / mechanical process. As a result, solid oxide fuel cells are not limited in efficiency by the Carnot cycle and theoretically highly efficient electrical generation is possible. A solid oxide fuel cell is described in Patent of E.U.A. No. 5,413,879 to Domeracki et al., Which is hereby incorporated by reference in its entirety. The patent discloses a solid oxide fuel cell having a gas-tight ceramic membrane separating an air chamber from a fuel chamber. The ceramic membrane is usually a three-layer mixed material having a portion of a gas-tight matrix formed of a ceramic membrane material such as zirconium sterilized with yttrium, which selectively transports oxygen ions by diffusion. A portion of the surface of the ceramic membrane in contact with the air is coated with an electrode that can be made of a lanthanum manganite contaminated with strontium. A portion of the opposite surface of the ceramic membrane in contact with the fuel is a fuel electrode that can be a nickel-zirconium cermet. The interconnections are provided on both electrodes which allows connecting several electric cells in series or in parallel and of pulling an electric current generated by the flow of ions. Suitable fuel cells are described in US Patents. Nos. 4,490,444 (Isenberg) and 4,728,584 (Isenberg), each of which is incorporated by reference in its entirety. The hot air is brought into contact with the air electrode and oxygen is separated from the air by transporting ions through the membrane to the surface of the fuel electrode. Normally a gaseous fuel such as light hydrocarbon such as natural gas or carbon monoxide, comes into contact with the surface of the electrode and reacts exothermically with the oxygen ions to produce electricity and heat as the result of internal losses. At the output of the fuel cells there is a partially hot oxygen depleted gas from the cathode or retentate side and the reaction or combustion products from the anode or permeate side. Systems that generate electrical energy using solid oxide fuel cells are limited to obtain efficiencies obtained due to several factors including: (1) internal electrical loss mainly in the electrodes, (2) high temperature in the scale of approximately 700 ° C at around 1,000 ° C at which the air should be heated; and (3) the fact that only a portion of the oxygen contained within hot air, normally in the order of between 20% to 30% by volume of the available oxygen, is transported through the ceramic membrane for reaction with the gaseous fuel. The rest of the oxygen is discharged into the retentate stream that leaves the air chamber. Some of the energy added to the retentate and permeate streams is lost as a result of the pressure drop and the limited effectiveness of the optional recuperative heat exchangers. The patent of E.U.A. No. 5,413,879 (Domeracki) describes the combination of reaction products of chemical reactions in the fuel chamber with the hot gas retentate of the air chamber and making it react with the additional fuel in a heater to further raise the temperature of the mixture. . The hot mixture heats a compressed gas that is used to drive a turbine. Various types of transport membrane are described in thePatent of E.U.A. No. 5,733,435 (Prassad et al.). For membranes that exhibit only ionic conductivity, the external electrodes are placed on the surfaces of the membrane and the electron current is returned through an external circuit. In the mixed conducting membranes, the electrons are transported to the side of the cathode internally, thus ending a circuit and obviating the need for external electrodes in pressure-driven mode. For the same application, double phase conductors can also be used, in which an ionic conductor is mixed with an electronic conductor.

The Patent of E.U.A. No. 4,793,904 to Mazanec et al., Which is hereby incorporated by reference in its entirety, discloses an ion transport membrane coated on both sides with an electrically conductive layer. A gas containing oxygen is contacted with one side of the membrane. The oxygen ions are transported through the membrane to the other side where the ions react with methane or similar hydrocarbons to form 'syngas'. The electrons released by the oxygen ions flow from the conductive layer to the external cables and can be used to generate electricity. A membrane of mixed conductor type, the membrane has the ability to selectively transport both oxygen ions and electrons. It is not necessary to provide an external electric field for the removal of the electrons released by the oxygen ions. The Patent of E.U.A. No. 5,306,411 to Mazanec et al., Which is incorporated herein by reference in its entirety, describes the application of dual-phase conductive mixed and conductive membranes. The membrane comprises mixed metal oxides in a "single phase" having the perovskite structure with ion and electron conductive properties or a multi-phase mixture of an electron conducting phase and an ion conducting phase. The transport of oxygen ions is described as being useful for forming 'syngas' and for remediating the flow of gases such as NOx and SOx.

The Patent of E.U.A. No. 5,516,359 to Kang et al. Discloses a ceramic ion transport membrane integrated with a high temperature process in which heat is effectively used for the operation of the membrane and the high temperature process. The compressed hot air is brought into contact with an oxygen selective ion transport membrane and a portion of the oxygen contained within the air is transported through the membrane and removed as a product gas. The oxygen depleted waste gas is combined with a gaseous fuel and reacted to generate a high temperature gas useful for driving a turbine that is normally driven by an air compressor and the generator to generate electric power. However, there is still a need for a process that integrates the ion transport reactors with the most efficient solid oxide fuel cell for the generation of one or more product gases and electrical energy to make an improvement in efficiency. OBJECTIVES OF THE INVENTION Therefore, it is an object of the invention to provide a process for the generation of electrical energy and one or more product gases including oxygen, nitrogen and carbon dioxide alone or in combination. It is a further object of the invention that said processes are efficiently integrated into the solid oxide fuel cell with an ion transport reactor. This objective is aided by the fact that the solid oxide fuel cells and the oxygen ion transport membranes have similar operating temperatures. Still another object of the invention is to use the currents leaving the solid oxide fuel cell as feed streams to the ion transport reactor and to use the current leaving the side of the retentate and optionally also from the permeate side of the membrane Selective ion transport of oxygen to drive a turbine. It is another object of the invention to utilize the heat generated on the anode side of the fuel cell as a result of the inefficient conversion of chemical energy into electrical energy, to heat the gas fed directly to the cathode of the oxygen transport separator at the operating temperature of the membrane. It is still another object of the invention to place the anode side of the fuel cell in series with the anode side with a reactive purged ion transport membrane and to add excess fuel to the anode feed of fuel cells to be available as a reactant in the purge stream and therefore raise the efficiency of the fuel cell energy conversion. COMPENDIUM OF THE INVENTION This invention comprises a process for the generation of electrical energy and one or more product gases of a gas containing oxygen and a gaseous fuel. A solid oxide fuel cell having a first side of the cathode or retentate and a first side of the anode or permeate is provided. A first ion transport reactor is provided having an oxygen selective ion transport membrane disposed thereon, the membrane having a second side of the cathode or retentate and a second side of the anode or permeate. The oxygen-containing gas is contacted with the first side of the cathode and a gaseous fuel is contacted with the first side of the anode causing a first portion of oxygen to be transported from the first side of the cathode to the first side of the anode as oxygen ions. Oxygen ions react with the gaseous fuel and generate heat and an electron flow that recovers as electrical energy. A retentate gas with remaining oxygen is directed from the first side of the cathode of the solid oxide fuel cell to the second side of the cathode of the first ion transport reactor causing a second portion of oxygen to be transported through the membrane of ceramic on the second side of the anode. At least one product gas was recovered from one or more of the first and second sides of the anode and cathode. In a preferred embodiment, the oxygen-containing gas is air and is compressed before contacting the first side of the cathode. Oxygen is recovered from the second side of the anode. A recovery heat exchanger transfers heat from the exothermic reaction outlets to the oxygen-containing gas and the first gaseous fuel stream of the solid oxide fuel cell. In another preferred embodiment, the heat generated in the fuel cell, as a result of the inefficient conversion of chemical energy to electric power from the anode-side reaction, provides at least part of the energy required to connect the air stream to the operating temperature of the oxygen transport membrane. Steam is used as a scavenging gas for the second side of the anode and the permeate of the second side of the anode comprises a mixture of oxygen vapor which is used to classify charcoal. A purge gas is contacted with the second side of the anode and a nitrogen gas with low oxygen content is recovered as the product gas. In yet another preferred embodiment, the reaction products generated on one side of the anode of the fuel cell are used to purge the anode from the oxygen transport separator. A second reactive purged ion transport reactor is disposed between the solid oxygen fuel cell and the first ion transport reactor. In a preferred embodiment the fuel required in a reactive oxygen reactor is added to the fuel feed and the fuel cell and to the anode sides of the fuel cell and the ion transport reactor is placed in series, thus increasing the efficiency of the fuel cell. The nitrogen product gas under pressure or the electrical energy generated in the solid oxide fuel series is used to drive the compressor that compresses the oxygen-containing gas. BRIEF DESCRIPTION OF THE DRAWINGS Other objectives, aspects and advantages will be presented to those skilled in the art from the following description of the preferred embodiments and the accompanying drawings, in which: Figure 1, schematically illustrates a solid oxide fuel cell integrated with a transport reactor of ceramic membrane ions according to the invention; Figure 2 schematically illustrates an integrated system for co-production of energy and oxygen; Figure 3 schematically illustrates an integrated system for co-production of energy and a mixture of oxygen and the useful stream to gasify charcoal. Figure 4 schematically illustrates an integrated system for the co-production of energy and nitrogen; Figure 5 illustrates schematically an integrated system for the co-production of energy, oxygen and nitrogen. Figure 6. Schematically illustrates another integrated system for the coproduction of electrical energy, oxygen and nitrogen; and Figure 7 illustrates schematically an integrated system for the production of essentially oxygen-free nitrogen. DETAILED DESCRIPTION OF THE INVENTION This invention can be achieved by integrating a solid oxide fuel cell with a ceramic membrane ion transport reactor. Preferably, a turbine with one or more streams leaving the integrated system is operated. The compressed air is supplied to the solid oxide fuel cell wherein a first portion of the oxygen contained within the air is transported through the ceramic membrane and reacts exothermically as a fuel gas to generate combustion products and electricity. A retentate stream of oxygen content will reduce its discharge to the solid oxide fuel cell cathode at the cathode of an ion transport reactor having an oxygen selective ion transport membrane. A second portion of the oxygen contained within the air is transported through the oxygen selective ion transport membrane and can be recovered as a product gas or used in downstream reactions. The retentate of the ion transport membrane, while substantially depleting oxygen, can still contain enough oxygen so that it is mixed in some embodiments with a gaseous fuel and burned to generate a high temperature gas to drive a turbine. Alternatively, nitrogen can be recovered from an oxygen depleted stream. Figure 1 schematically illustrates a process integrating a solid oxide fuel cell 10 and a first ion transport reactor 11 according to the invention. The solid oxide fuel cell 10 has a ceramic membrane 12 that divides the solid oxide fuel cell 10 into a first side of the cathode 14 and a first side of the anode 16. The ceramic membrane 12 is selective for oxygen and transport of oxygen ions from the first side of the cathode 14 to the first side of the anode 16. A suitable material for the ceramic membrane 12 is zirconium stabilized with yttrium. A porous air electrode 18 substantially covers the entire first side of the cathode 14. A suitable material for the air electrode 18 is lanthanum manganite contaminated with strontium. A first interconnection portion 22 is not coated with the air electrode 18 and is electrically connected to a load 24. The oxygen ions are transported through the ceramic membrane 12 to the first side of the anode 16 which is coated with an electrode of process 26 fuel except for a portion of electrical interconnection. The fuel electrode 26 can be made of any material that effectively minimizes polarization losses and is stable to reduce the atmosphere such as a nickel-zirconium cermet. An oxygen-containing gas supply 28 is supplied to the first side of the cathode 14 and a gaseous fuel 30 is supplied to the first side of the anode 16. The oxygen-containing gas supply 28, usually air, is supplied to the cathode side of the fuel cell at a somewhat low temperature (usually 200 to 700 ° C or less) of the operating temperature of the fuel cell to act as a heat vessel for the heat generated by the reaction of fuel cells. The operating temperature of the solid oxide fuel cell 10 is usually at a temperature above 500 ° C and preferably on the scale from about 700 ° C to about 1, 000 ° C. The oxygen molecules in the feed air dissociate from the elemental oxygen in contact with the air electrode 18. "Elemental oxygen" refers to oxygen that does not combine with other elements of the periodic table. While normally in diatomic form, the term "elemental oxygen", as used herein, is intended to encompass oxygen atoms alone, triatomic ozone, and other forms not combined with other elements. Air is preferred as the oxygen-containing gas feed 28. The oxygen-containing gas feed 28 is preferably compressed, usually at a pressure of between 206.7 and 2067 kPa, and more preferably at a pressure between 689 kPa and 1584.7 kPa, by the compressor 32. The feed containing compressed oxygen is then preferably heated to an intermediate temperature of between about 300 ° C to about 800 ° C and more preferably at a temperature of about 500 ° C to about 700 ° C and then is supplied to the first side of the cathode 14. The final heating of the supply air to the fuel cell and to the temperatures operating the oxygen transport membrane occurs inside the fuel cell by virtue of the portion of the chemical energy of the fuel cell. the reaction of the anode side that is not converted into electrical energy but is released as heat which in turn is transferred to raise the temperature of the supply current to the required level. The gaseous fuel 30 is any gas or combination of gases having a constituent that reacts exothermically with the elemental oxygen. The reactive constituent can be natural gas or mixtures of light hydrocarbons, methane, carbon monoxide or synthesis gas ("syngas"). Syngas is a mixture of hydrogen and carbon monoxide with a moral H2 / CO ratio of about 0.6 to about 6.0. An additional component of the fuel gas, which may undesirably be in the fuel cell, in some embodiments is a non-reactive diluent gas such as nitrogen, carbon dioxide or steam. The gaseous fuel 30 is preheated to a temperature of about 300 ° C to about 900 ° C and is introduced to the first side of the anode 16. The reactive constituents of gaseous fuel 30 react exothermically with elemental oxygen. The electrons 34 released from the oxygen ions provide electrical energy to the load 24. A portion of the oxygen contained in the gas supply containing oxygen 28 is consumed by the reaction on the first side of the anode 16. A retentate stream 38 with the reduced oxygen content is then conducted to a second of the sample 40 which is a portion of a first ion transport reactor 11. The first ion transport reactor 11 has an oxygen selective ion transport membrane 44 which separates the first ion transport reactor 11 on a second side of the cathode 40 and a second side of the anode 50. By "oxygen selective" it is meant that the oxygen ions are preferentially transported through the oxygen selective ion transport membrane 44, from the second side of the cathode 40 to the second side of the anode 50, over other elements and ions thereof. The oxygen selective ion transport membrane 44 is made of inorganic oxides, typified by zirconium stabilized with calcium or yttrium. At elevated temperatures, generally in excess of 400 ° C, the oxygen selective ion transport membrane 44 contains void mobile oxygen ion sites that provide conduction sites for the selective transport of oxygen ions through the membrane. The transport through the membrane is driven by the ratio of the partial pressure of oxygen (Po2) through the membrane: the ions O "flow from the side with high P02 to the side with low P02. "takes place on the second side of the cathode 40 and the ions are transported to the second side of the anode 50 where 02 is recovered as a product gas. The oxygen selective ion transport membrane 44 is formed as a dense wall solid oxide blended into a double phase conductor or alternatively as a mixed thin film solid oxide or a double phase conductor which is supported on a porous substrate. The selective oxygen ion transport membrane 44 has a nominal thickness of less than 5, 000 microns and preferably is less than 1,000 microns thick. The oxygen selective ion transport membrane 44 transports oxygen and electron ions into the oxygen partial pressure on the temperature scale from about 450 ° C to about 1200 ° C when a potential chemical difference across the surface is maintained of ion transport membrane caused by a ratio of partial pressures of oxygen through an ion transport membrane. The oxygen ion conductivity is normally in the range of 0.01 to 100 S / cm where S ("Siemens") is reciprocal to ohms (1 / O). Suitable materials for the oxygen selective ion transport membrane include perovskites and double phase metal-metal oxide combinations as listed in Table 2 of the U.S. Patent. No. 5,733,345 which is also incorporated by reference in its entirety. See also the materials described in the Patents of E.U.A. Nos. 5,702,999 (Mazanec) and 5,712,220 (Carolan et al.). A material with a high ion conductivity, at least 0.5 and preferably at least 1 S / cm at 900 ° C, is desired for the membrane 44 since the driving force for oxygen transport will normally be small (<10th). A suitable material could be a mixture of lanthanum, strontium and cobalt oxides.

Optionally, a porous catalyst layer, in some form, made from the same perovskite material as the material of the dense membrane layer, is added to one or both sides of the oxygen selective ion transport membrane 44 to increase the efficiency of the membrane. exchange of oxygen surface in chemical reactions on surfaces. Alternatively, the surface layers of the oxygen selective ion transport membrane 44 can be contaminated, for example, with cobalt to increase the surface exchange kinetics. The first ion transport reactor 11 is operated at an elevated temperature which is sufficient to facilitate the transport of ions through the oxygen selective ion transport membrane 44. The operating temperature is at least 400 ° C, preferably on the scale of about 400 ° C to about 1,200 ° C and more preferably on the scale of about 400 ° C to about 1,000 ° C. Approximately 30% to 60% by volume of the oxygen retained at the reduced oxygen gas feed outlet is transported through the oxygen selective ion transport membrane 44 and recovered as oxygen product gas 52. Ei The percentage of oxygen that can be recovered depends on the respective partial pressures of oxygen on the second side of the cathode 40 and the second side of the anode 50. The percentage of oxygen recovered can be improved by reducing the partial pressure of oxygen on the second side of the anode 50 by the use of a sweeping gas on the second side of the anode or vacuum pump. Purge gases are oxygen removal gases such as natural gas, methane, methanol, ethanol and hydrogen. A scavenging gas is a non-reactive gas that reduces the partial pressure of oxygen. Suitable scavenging gases include carbon dioxide and steam. Optionally an oxygen depleted retentate stream 54 is directly expanded in a turbine 62 to generate the turbine energy 64 or it can be supplied to a combustion apparatus 56 and reacted with a second gaseous fuel 58. The combustion products 60 are a high temperature gas with low oxygen content that can be used to drive the turbine 62 to generate a turbine arrow energy 64. The efficiency of the process illustrated in Figure 1 is increased by the arrangement schematically illustrated by Figure 2. A Recovery heat exchanger 66 recovers the heat rejected from the high temperature gases such as product gas 52, combustion products 68 from solid oxide combustion cells 10 and combustion products 60 from combustion apparatus 58. Optionally, the Oxygen depleted outlet 54 is derived from the combustion apparatus 56 and rejects heat to the recuperative heat exchanger 66 The heat is used to raise the temperature of the gas feed containing oxygen 28 and the gaseous fuel 30. The combustion products 68 can be discharged after recovering the waste heat as illustrated in Figure 2. Alternatively, the Combustion products 68 are conducted to the second side of the anode 50 with a sweeping gas, shaded as arrow 68a to increase oxygen transport and recovery. In this alternative embodiment, the product gas 52 contains oxygen, water and carbon dioxide. After condensing the water, an oxygen stream with low purity diluted with carbon dioxide was recovered. If desired, the oxygen product gases and carbon dioxide can be separated by a downstream process such as thermal oscillating adsorption or polymer membranes. The reactive purge arrangements are described in "Reactive Purge for Solid Electrolyte Membrane Gas Separation ", US Series No. 08 / 567,699, filed December 5, 1995, EP Publication No. 778,069 and incorporated herein by reference.The preferred configurations for ion transport modules that utilize A reactive purge is described in "Solid Electrolyte Lonic Conductor Reactor Design," US Series No. 08 / 848,204, filed April 29, 1997 and also incorporated herein by reference, both applications commonly pertaining to the in-process application.

The oxygen depleted retentate 54, Figure 2, contains between 6% and 12% by volume of residual oxygen and can be discharged 70 after rejecting heat to the recovery heat exchanger 66, or alternatively, a portion 70 ', or all of the oxygen depleted retentate expands in turbine 62 to recover energy. Since the oxygen depleted retentate 54 contains some residual oxygen, a combustion apparatus 56 upstream of the turbine 62 can be inserted and the oxygen depleted retentate reacted with the second gaseous fuel 58 to raise the inlet temperature of the gas. turbine 62 between 1100 ° C and 1500 ° C increasing both the energy generated and the thermal efficiency of the system. In the absence of the combustion apparatus 56 or if the expanded stream 60 is at a very low temperature, the energy required to sustain the operation of the integrated system illustrated in Figure 2 is provided by the heat generated in the solid oxide fuel cell. The amount of heat generated depends on the efficiency of the solid oxide fuel cell 10 to convert chemical energy to electrical energy. This efficiency, in turn, dictates that the portion 70 'of the oxygen-depleted retentate stream 54 that can be expanded in the turbine 62, if the heat generated by the solid oxide fuel cell 10 is inadequate, a portion of the largest heat contained within the stream 54 in the recovery heat exchanger 66 to preheat the supply of oxygen-containing gas 28 and the gaseous fuel 30. In an alternative embodiment, the recovery heat exchanger 66 is replaced by a combustion apparatus (not shown) which is placed upstream of the solid oxide fuel cell 10 to preheat the supply of oxygen-containing gas 28 and gaseous fuel 30. Figure 3 schematically illustrates an application of the integrated system that provides both oxygen and steam to a charcoal gasifier. As described in the U.S. Patent Application. Series No. 08 / 972,412 co-pending common property (D-20, 365) that was filed on November 18, 1997, charcoal gasifiers require both steam and oxygen, usually at a molar ratio of approximately 1: 2 and pressure eievada. In this embodiment, the air stream 28, the fuel stream 30 and the combustion product stream 68 of the fuel cell 10 are similar to those of Figure 2. The retentate stream 54 of the module 11, Figure 3, it is passed directly through the exchanger 66 and / or through the combustion apparatus 56 'and the turbine 62'. The second side of the anode 50 of the module 11 is swept with the stream 72 to increase oxygen transport through the oxygen selective ion transport membrane 44 and decreasing the average oxygen partial pressure on the second side of the anode 50. The advantages of sweeping the vapor are discussed in the US Patent Application Series No. 08 / 972,020 co-pending, common property (Attorney Case No. D-20, 345) filed on November 18, 1997 and which is also incorporated herein by reference in its entirety. The steam 72 is a part of the process cycle 73 integrated into the modulate fuel shutdown / ion transport system. The feed water 74 is pumped to a required pressure, usually in the order of 1033.5 kPa to 4134 kPa, by the pump 76 and then evaporated and overheated, such as in the recovery heat exchanger 66 to produce steam 72. The permeate stream 78 contains a mixture of residual oxygen and steam. The stream 78, in a first embodiment, is injected directly into a charcoal gasifier 80 (shown as stream 102, but without the addition of stream 100 ', described above). In a second embodiment, the stream 78 is divided into a first portion 82 injected into the charcoal gasifier 80 and a second portion 84 that expands in the turbine 63., it is cooled and supplied to a condenser 86. The majority of the current is condensed in the condenser 86 and the outlet of the condenser 88 is a mixture of liquid water and oxygen saturated with water. The water is separated from the mixture in a separator 90 and the recycled water 92 is mixed with forming feed water 74. The water-saturated oxygen 94 removed from the separator 90 is cooled in a cooler 96 and compressed in the compressor 98. The compressed stream 100 is reheated, so that it passes through the recovery heat exchanger 66 as hot stream 100 'and then mixes with the first permeate stream portion 82 to produce the stream 102. Controlling the ratio of the first portion 82 and compressed stream 100 to form stream 102, the desired vapor to oxygen ratio is obtained for the charcoal gasifier 80. The advantages of the system schematically illustrated in Figure 3 over a separate generation and current injection and oxygen to a charcoal gasifier, include a reduction in the ion transport membrane area required and savings in energy req uring to compress oxygen. By mixing a stream containing steam and oxygen with a second stream of high oxygen content, a better control of the vapor to oxygen ratio is achieved. The use of steam as a scavenging gas allows to operate the cathode sides of the fuel cell ion transport reactor at pressures lower than the gasifier pressure, while saving oxygen compression energy. Alternatively, a condenser (not shown) can be used to remove water from outlet 78 to obtain a lower ratio of vapor to oxygen. However, this spends much of the energy contained within the portion of the outlet 78 that condenses reducing the efficiency of the system.

Figure 4 schematically illustrates an integrated system having a solid oxide fuel cell 10 and a first ion transport reactor 11 useful for co-production of energy and nitrogen. The oxygen-containing feed gas 28, normally air, is compressed by the compressor 32 at a pressure between about 310.05 kPa and 1136.85 kPa. The compressed air is then heated, such as by the recovery heat exchanger 66 to a temperature between about 200 ° C and 700 ° C, and by introducing it to the first side of the cathode 14 of the fuel cell 10. Approximately 60% at 70% by volume of oxygen contained within the oxygen-containing gas feed 28 is transported through the ceramic membrane 12 and reacted exothermically with the gaseous fuel 30. Maintaining a relatively high pressure on the first side of the cathode 14, a relatively high partial pressure of oxygen is maintained allowing a large volume fraction of the oxygen to be transported through the ceramic membrane 12 and therefore a reasonable conversion efficiency is obtained. Due to the important exothermic reactions that occur on the first side of the anode 16, additional cooling may be required to avoid an excessive temperature rise. The retentate 38 having a reduced oxygen content is supplied to the first ion transport reactor 11 to complete the removal of oxygen from the cathode side stream. The oxygen is transported through the oxygen selective ion transport membrane 44 and reacts exothermically with the gaseous fuel 30 'on the second side of the anode 50. The heat of this exothermic reaction is absorbed into a heater section 39 by elevation at the temperature of the augmentation current on the side of the cathode 38 'which, as the current 38, was cooled in the heat exchanger 66 or in the optional cooler 66'. The retentate of stream 54 contains less than about 10 ppm of oxygen and can be supplied at a pressure such as a high pressure of nitrogen product 104 after the removal of useful heat by the recovery heat exchanger 66. Alternatively, at less a portion of the oxygen depleted stream 54 is expanded to the turbine 62 and recovered as a low pressure nitrogen product 106. A first portion of the gaseous fuel 30 is supplied to the first side of the anode 16 of the fuel cell of solid oxide 10. A second portion 30 'of the gaseous fuel 30 can be supplied directly to the second side of the anode 50 of the first ion transport reactor 11. Preferably, the combustion products 68 serve as a diluent and combine at the junction 108 with the second portion 30 'of the gaseous fuel gas 30 for purging the second side of the anode 50. More preferably, all the fuel gaseous 30 passes through the first side of the anode 16 to increase the average fuel pressure at the solid oxide fuel cell anode 10 and thus increase the efficiency of the fuel cell to a maximum since a high partial fuel pressure will increase the reaction kinetics of the anode of the fuel cell and thus minimize polarization losses. The gas in the permeate 52 is substantially water vapor and carbon dioxide, since the nitrogen is excluded from the anode-side reactions, except for trace amounts contained within the fuel. If desired, a carbon dioxide product 109 can be recovered after condensing the water. The system illustrated schematically in Figure 4 generates a significant excess of heat because all the oxygen contained in the oxygen-containing gas supply 28 is reacted exothermically with the gaseous fuel 30. In small systems, this heat can be used to generate steam to export it from the system. In larger systems, the excess heat can be used to produce additional energy through a Rankine 110 cycle, shown shaken. In a Rankine cycle, excess heat is directed to a heater where the heat exchanges the water in the over-heated steam. The expansion of steam to a lower pressure steam drives a turbine to generate energy from the arrow. The heat is then removed in a condenser since the steam is converted back to a saturated liquid of low pressure. Then a pump returns to the heater pressure. The heat for the Rankine 110 cycle is preferably removed from the streams 38 and / or 54. Figure 5 illustrates a system for the co-generation of nitrogen and oxygen. A second ion transport reactor 112 is disposed between the solid oxide fuel cell 10 and the first ion transport reactor 11. An oxygen-containing gas feed 28, usually air, is compressed at a pressure between 689 kPa and 2067 kPa by a compressor 32 and heated, as by the recovery heat exchanger 66 to a temperature of between about 300 ° C and about 800 ° C. The gas supply containing hot oxygen 28 is supplied to the first side of the cathode 14. Approximately 20% to 25% by volume of the oxygen contained within the oxygen-containing gas supply 28 is transported through the ceramic membrane 12 to reacting exothermically with the gaseous fuel 30 generating electrical energy supplied to the load 24 and heat. The heat is effective to raise the temperature of the partially depleted retentate stream of oxygen 38 to a temperature on the scale from about 900 ° C to about 1,000 ° C. The partially depleted oxygen gas stream 38 is now at an effective temperature for oxygen separation in the second ion transport reactor 112 and approximately 48% to 60% of the remaining oxygen is transported through an ion transport membrane. selective oxygen 114 and recovered as oxygen product 116. A low oxygen retentate stream 118 discharged from the second ion transport reactor 112 rejects heat to the heat exchanger 120. The heat rejected can be used for an energy cycle External rankine, supplied to the recovery heat exchanger 66 to form thermal deficiencies in other parts of the system, or discharge them as waste. A reduced temperature usually in the order of 300 to 700 ° C, with low oxygen content stream 122 is introduced on the second side of the cathode 40 of the first ion transport reactor 11. Normally, the oxygen content in the gas of feed to the side of the cathode 40 of the first ion transport reactor 11 will be between 2% to 7% by volume, depending on whether a sweeping gas is introduced (a suitable source could be the stream 52 consisting of combustion products) to the third anode side 124 of the second ion transport reactor 112 to reduce the partial pressure of oxygen on the third side of the anode, thus increasing the driving force for oxygen transport through the oxygen selective ion transport membrane 114 The lower value is achieved if a sweeping gas is used. The remaining oxygen is transported through the oxygen selective ion transport membrane 44 and reacted exothermically with gaseous fuel 30, or with a mixture of fuel and combustion product 60 where all the fuel is introduced to the anode of the gas. fuel cell 10, on the anode side 50 of the first ion transport reactor 11. The retentate on the cathode side 40, the oxygen depleted gas stream 54, usually has an oxygen content less than a. 10 parts per million. As described above, the oxygen depleted gas stream 54 can be recovered as a high pressure nitrogen product., as a low pressure nitrogen product 106 after the current 54 'expands in the gas turbine producing gas 62, or a combination thereof. The product gas 52 on the second side of anode 50 can be cooled to recover carbon dioxide 109 and water vapor. Alternatively, the product gas 52 can be supplied to the anode side 124 over the second ion transport reactor 112, in which case the permeate stream 116 contains a mixture of carbon dioxide, oxygen and water vapor. If the water vapor is removed, such as by condensation, the gas will contain approximately 75% to 92% by volume of oxygen. Pure oxygen is obtained, after separation and recovery of carbon dioxide and additional drying. The advantages of the invention described herein will be more apparent from the following examples: Example 1 Figure 6 illustrates schematically a system integrating a solid oxide fuel cell 10, a first ion transport reactor 11 and a second ion transport reactor 112 to co-produce electrical energy for the load 24, oxygen as product gas 52 and high pressure nitrogen 104 and low pressure nitrogen 106. The product streams of nitrogen are provided so that the energy produced by the gas turbine 138 is sufficient to drive the air compressor 32. An oxygen-containing gas supply 28, air, is compressed by the compressor 32 at a pressure to about 1067.95 kPa and after having been pre-heated in the recovery gas exchanger 66 it is supplied to the first side of the cathode 14 and where it is further heated to a temperature of about 950 ° C due to the heat generated by the exothermic reactions that occur on the first side of the anode 16. The solid oxide fuel cell 10 generates electrical energy that is extracted and after conditioning is supplied to the load 24, such as an external power grid. The oxygen content of the partially depleted oxygen gas stream 38 is about 15% by volume. The stream 38 is supplied to the third side of the cathode 126 of the second ion transport reactor 112. The oxygen corresponding to the 12% content in the feed air is conveyed through the second oxygen selective ion transport membrane 114. so that the oxygen content of the retentate stream 118 contains about 6% oxygen by volume. Stream 118 is at an elevated temperature and rejects heat in a first superheater 128 to steam stream 130. Stream 122, now at a reduced temperature, is introduced to the second side of cathode 40 where the residual oxygen contained it is removed by a stream of reaction purge gas 68, which normally consists of fuel and combustion products coming from the first side of the anode 16 of the first ion transport reactor 11. The oxygen depleted stream 54, now a stream of nitrogen with high purity, it is divided into the junction 132 in a first stream 134 which is recovered as a high pressure nitrogen product 104 and a second stream 136 which expands in the turbine 138 which drives the compressor 32. The separation between the currents 136 and 134 is provided so that the energy supplied by the turbine 138 satisfies the requirements of the compressor 32 when the turbine and the compressor are coupled mechanically The flow in excess of that required is recovered as high pressure nitrogen product 104. The waste heat of the second expanded stream 140 is recovered by the Rankine 110 cycle before being discharged from the system as low pressure nitrogen stream 106. The fuel gaseous 30 is heated in the recovery heat exchanger 66 and is supplied to the second side of the anode 16. On the first side of the anode 16, the gaseous fuel 30 reacts exothermically with transported oxygen to produce electrical energy and heat. The permeate stream 68 leaving the first side of the anode 16 contains unburned fuel and combustion products and is introduced to the second side of the anode 50 of the first ion transport reactor 11 to serve as the reactive purge stream for the removal of residual oxygen from the partially depleted oxygen gas supply 122. Permeate 144 from the second anode side contains mainly the combustion products (carbon dioxide and water vapor) and is discharged after recovery of useful heat in the recovery heat exchanger 66. Alternatively, the gaseous fuel 30 is compressed by a conventional element (not shown) and the first side of the anode 16 and the second side of the anode 50 are then operated at approximately the same pressure as the first and second sides of cathode 14 and 40. If this is done, the side products of the combustion anode can be supplied at pressure the increased downstream recovery of carbon dioxide or, if a carbon dioxide co-product is not desired, it is added to the second stream of high pressure nitrogen 136 and expanded. This will allow the recovery of additional high pressure nitrogen as product 140 or the export of additional energy. The third side of the anode 124 is purged by a scavenging gas (steam in this construction) generated by pumping the feed water 74 by the pump 76 at a pressure of about 6890 kPa and supplying it to a boiler / heater 146 which converts it into steam 130. The steam is then superheated in a second heater envelope 148 at a temperature that is sufficient to prevent condensation and moisture during subsequent expansion at a pressure of approximately 1033.5 kPa in high pressure turbine 150. Expanded stream 130 is reheated in the first superheater 128 and used to purge the third side of the anode 124. This enhances oxygen recovery and increases the driving force for oxygen transport. Said application for a steam circuit is described more fully in the U.S. Patent Application. Series No. 08 / 972,020 of common property, co-pending (Document Case No. D-20, 345) which is incorporated herein by reference. The stream 78 has an oxygen partial pressure of about 137.8 kPa and is supplied to a low pressure steam turbine 152 at a pressure of about 1033.5 kPa. The expanded outlet 154, now at a pressure of 110.24 kPa, is cooled in the second superheater 148 providing the heat required to superheat the vapor 130. The cooled outlet stream 156 enters the condenser 158 where a major portion of water contained it condenses, allowing the recovery of oxygen as product gas 52 from the separator 90. The recycled water 92 can be combined with the feed water to return it to the pump 76 and thus return it to a pressure of 6890 kPa to complete the circuit. steam. Table 1 identifies the inputs used to model the system illustrated in Figure 6, Table 1 The results calculated for the system are tabulated n in Table 2. Table 2 The results of Table 2 exhibit a very attractive performance potential in terms of heat regimes performed regardless of the relatively moderate peak temperatures employed in the cycle while respectable oxygen recoveries are obtained in comparison with conventional systems. As an additional benefit, a significant fraction of the nitrogen contained in the air is supplied with pressure. Example 2 Figure 7 schematically represents another integrated system according to the. invention. This system is particularly effective for the production of nitrogen essentially free of nitrogen with the option of co-production of oxygen and carbon dioxide. Using the parameters presented in Table 3 below, the solid oxide fuel cell 10 is sized to supply sufficient energy to drive the air compressor 162. An oxygen-containing gas feed, preferably air, is compressed by the compressor of air 162 at a pressure of approximately 1067.95 kPa. The compressed air is then preheated, so by means of the recovery heat exchanger 66, at a temperature of about 800 ° C and introduced to the first side of the cathode 14 of the solid oxide fuel cell. The gaseous fuel 30 is introduced to the first side of the anode 16 and reacted exothermically with oxygen ions transported through the ceramic membrane 12 generating heat, electrical and anode side current 68 which is a mixture of combustion products and gaseous fuel. The generated electrical energy is used to drive an electric motor 164 that drives the air compressor 162. The partially exhausted oxygen retentate stream 38 leaving the solid oxide fuel cell 10 is at a temperature of about 950 ° C. About 12% by volume of oxygen contained in the air is consumed by the reaction with the gaseous fuel 30 on the first side of the anode 16. The partially depleted oxygen stream 38 is conducted to the third side of the cathode 126 of the second transport reactor of ions 112 where about 60% by volume of the remaining oxygen is transported through the second selective ion transport membrane 114. To increase the removal and potential recovery of a contained significant fraction of oxygen within stream 38, the third side of the anode 124 is swept with combustion products from the first side of the anode 16, the second side of the anode 50 or the combination of both. The scavenging gas reduces the partial pressure of oxygen on the third side of the anode 124 to increase the oxygen recovery and / or the driving potential for the oxygen transfer. The retentate stream 118 of the third side of the cathode 126 contains about 6 volume% oxygen. The stream 118 is cooled in the heat exchange 166 by producing a reduced temperature stream 122 to function as a heat sink 168 to absorb heat from the reaction generated downstream in the first ion transport reactor 11. The heat rejected from the Retentate stream with low oxygen content 118 in heat exchanger 166 can be used to raise steam 170 for export or other uses. The reduced temperature stream 122 is supplied to the second side of the cathode 40 where the rest of the contained oxygen is transported through the oxygen selective ion transport membrane 44 and reacts with the gaseous fuel contained within the gaseous fuel mixture. / combustion products 68 on the second side of the anode 50. The oxygen depleted gas stream 54 removed from the second side of the cathode 40 contains less than 10 ppm of oxygen and can be supplied, after recovery of useful heat, as a high pressure nitrogen product 104. The gaseous fuel 30 is preheated in the recovery heat exchanger 66 and is supplied to the first side of the anode 16 and reacts with oxygen carried through the ceramic membrane 12 of the first side of the cathode. Since the gaseous fuel 30 also contains the fuel required in the first oxygen transport reactor 11, the average partial pressure of the gaseous fuel in the solid oxide fuel cell 10 is raised to increase the efficiency. The outlet permeate stream 68 contains gaseous fuel diluted by the combustion products and enters the second anode side 50 of the first ion transport reactor 11 to remove the oxygen transported through the ceramic membrane 44 and the second side of the cathode 40 by a reactive purge. The leaving permeate stream 144 contains combustion products, a mixture of water vapor and carbon dioxide and is useful as a scavenging gas to purge the third anode side 124 of the second ion transport reactor 112. The flow of Permeate 78 leaving the second ion transport reactor 112 contains a mixture of combustion products and oxygen. After recovery of waste heat from waste in the recovery heat exchanger 66, the condenser 158 and the separator 160 are used to recover an oxygen product gas with low purity 52 containing about 75% by volume, of oxygen with the volume of the impurities being carbon dioxide. If required, carbon dioxide can be removed from a downstream process and oxygen can be recovered. The recycled water 92 is properly discharged. If oxygen or carbon dioxide is not desired, the stream 78 may also be discharged after the recovery of useful heat in the recuperator 66. Table 3 identifies the input parameters for the system illustrated schematically in Figure 7.

Table 3 The results of the calculations using the entries in Table 3 are tabulated in Table 4.

Table 4 An advantage of the system illustrated in Figure 7 is that the efficiency is inced by the availability of the fuel diluent, in the form of combustion products of the cell 42 solid oxide fuel 10 and the first 1 1 ion transport tor to purge the second 1 12 ion transport tor. This allows high nitrogen and oxygen recovery regimes. A non-integrated separation system (separate fuel cell that drives the compressor or an independent ion transport membrane) could be burned by the additional capital expense of separate air and fuel circuits, the capital and energy disadvantages due to a larger fuel cell that is required to supply the energy of understanding of air for both systems and disadvantages of higher energy due to the losses of final cooling temperature differential, probably resulting in the use of less efficient fuel. The specific aspects of the invention are shown in one or more of the drawings for convenience only, since each aspect may be combined with other aspects according to the invention. The alternative modalities will be recognized by the aspects in the matter and are intended to be included within the scope of the claims.

Claims (10)

1. REVIVAL NAME IS 1. A process for the generation of electric power and a product gas stream of a mixture of an oxygen containing stream gas and a first gaseous fuel stream, comprising: (a) providing a solid oxide fuel cell having a first side of the cathode and a first side of the anode; (b) providing a first ion transport reactor having therein an oxygen selective ion transport membrane, the oxygen selective ion transport membrane having a second side of the cathode and a second side of the anode, (c ) contacting the gas stream containing oxygen with the first side of the cathode and contacting the first gaseous fuel stream with the first side of the anode; (d) transporting a first oxygen portion of the oxygen-containing gas stream from the first cathode side to the first side of the anode; (e) reacting the first portion of oxygen with the first gaseous fuel stream on the first side of the anode and generating a flow of electrons from the first side of the anode to the first side of the cathode; (f) recover the flow of electrons as electrical energy; (g) directing a remainder of the gas stream containing oxygen not as a first retentate stream from the first side of the cathode to the next side of the cathode; (h) contacting the first retentate stream with the second side of the cathode and transporting a second portion of oxygen from the second side of the cathode to the second side of the anode; and (i) recovering a gas stream as the product gas stream from at least one first side of the cathode, the first side of the anode, the second side of the cathode and the second side of the anode.
2. 2. The process of claim 1, wherein the gas stream containing oxygen includes air.
3. 3. The process of claim 2, further including compressing air before contacting the first side of the cathode.
4. 4. The process of claim 3, further including recovering oxygen as product gas stream from the second side of the anode.
5. 5. The process of claim 4, further including reacting a retentate gas stream exiting the second side of the cathode with a second gaseous fuel stream to generate combustion products.
6. 6. The process of claim 5, wherein the combustion products are used to drive a turbine. The process of claim 2, wherein a recovery heat exchanger transfers heat of at least one current, after contacting the current with at least one of the first and second sides of the cathode and anode, said air and the first gaseous fuel stream upstream of the solid oxide fuel cell. The process of claim 2, which further includes sweeping the second side of the anode with steam at an elevated pressure whereby a permeate gas stream leaving the second side of the anode contains a mixture of steam and oxygen. The process of claim 8, further including adjusting the vapor to oxygen ratio in the permeate gas stream from the second side of the anode to an effective molar ratio for charcoal gasification. The process of claim 9, wherein the adjustment step comprises dividing the permeate gas stream from the second side of the anode into a first portion and a second portion, cooling the second portion, condensing water from the second portion, compressing the remaining gas from the second portion back to the pressure of the permeate gas stream and then recombining the first portion and the second portion.