Apparatus and method for generating nitrogen by dehumidifying and filtering fuel cell exhaust

Abstract

Provided is a device / system for reliably and stably producing high-purity nitrogen using a fuel cell. The nitrogen generating device / system includes: a fuel cell that operates by taking in air or a gas containing nitrogen and oxygen, and a fuel gas; a dehumidification mechanism that reduces the moisture or water vapor content in exhaust gas extracted from the fuel cell and having a lower oxygen concentration than air; and a filtering mechanism that includes a filter using fibers having different permeabilities to nitrogen and oxygen and converts the exhaust gas with reduced moisture or water vapor content into a gas with an increased nitrogen concentration. Here, the filter is preferably a filter in which the recovery rate is higher when the oxygen concentration of the gas to be filtered is lower. In addition, the dehumidification mechanism is preferably a pump unit including a water seal pump, and in this case, an adiabatic expansion chamber is preferably provided in which the exhaust gas extracted from the fuel cell is adiabatically expanded.

Description

Technical Field

[0001] The present invention relates to a technology for generating high-purity nitrogen. Background Art

[0002] Priority is claimed under the Paris Convention on Japanese Patent Application No. JP2020-029364 filed on February 25, 2020, and Japanese Patent Application No. JP2021-010474 filed on January 26, 2021, and the contents of these Japanese patent application publications are incorporated herein by reference under PCT Rule 20.6.

[0003] In recent years, the use of fuel cells has been actively promoted. For example, fuel cell vehicles have entered practical use, and domestic and industrial fuel cell facilities have become available. Fuel cells not only achieve efficient power generation but also, unlike conventional power generation systems using internal combustion engines, can reduce carbon dioxide emissions to approximately zero. Therefore, fuel cell technology is expected to significantly contribute to the realization of a zero-carbon society.

[0004] The inventors of the present invention focused on the potential of such fuel cells and invented welding devices using fuel cells as described in PTLs 1 and 2. In the welding devices, not only the electricity generated by the fuel cell but also the exhaust gas generated by power generation is supplied to and used in the welding devices.

[0005] Furthermore, as described in PTLs 3 and 4, the present inventors have also invented a power generation device using a fuel cell. This power generation device supplies an inert gas and electricity to a processing device, which uses the electricity to heat and process an object to be heated in the inert gas. This power generation device can remove or reduce the oxygen content and water vapor content / moisture content contained in the exhaust gas from the fuel cell, and can convert the exhaust gas into an inert gas suitable for use in the processing device.

[0006] Furthermore, as described in PTL 5, the inventors of the present invention have invented a power supply and gas supply device in which N fuel cell sections, from a first fuel cell section to an Nth fuel cell section, are connected and oxygen-depleted gas having a sufficiently small amount of oxygen can be supplied. Furthermore, as described in PTL 6, the inventors of the present invention have also invented a nitrogen generation device in which air and fuel gas having a pressure exceeding atmospheric pressure are supplied to a fuel cell, the fuel cell is operated, exhaust gas having a pressure exceeding atmospheric pressure extracted from the fuel cell is applied to a nitrogen filter having a pressure exceeding atmospheric pressure, and gas having an increased nitrogen concentration is extracted from the filter.

[0007] Citation list

[0008] Patent Literature

[0009] [PTL 1] Japanese Patent Application Publication No. 2013-233549

[0010] [PTL 2] Japanese Patent Application Publication No. 2016-164987

[0011] [PTL 3] Japanese Patent Application Publication No. 2017-084796

[0012] [PTL 4] Japanese Patent Application Publication No. 2018-163890

[0013] [PTL 5] Japanese Patent Application Publication No. 2019-129110

[0014] [PTL 6] Japanese Patent Application Publication No. 2020-149838 Summary of the Invention

[0015] Technical issues

[0016] In this way, the inventors of the present invention concluded that high-purity nitrogen gas, which is in great demand at various production / service provision sites, can be supplied by using fuel cells.

[0017] Such high-purity nitrogen is an inert gas that is neither combustion-supporting nor flammable and is a very useful gas, and currently, it is currently produced from air as a raw material through a pressure swing adsorption (PSA) method, a cold air separation method, a membrane separation method, and the like.

[0018] Here, it is believed that high-purity nitrogen can be efficiently produced using exhaust gas from a fuel cell, rather than directly using air as a raw material as in conventional technology. In addition, of course, since a fuel cell is used, electricity and high-purity nitrogen can be supplied.

[0019] However, the exhaust gas extracted from the fuel cell generally contains a large amount of water (H2O) produced by the fuel cell reaction, and its relative humidity is about 100%. Therefore, if it is used without any modification, it will have a negative impact on the subsequent high-purification process and become difficult to process reliably and stably.

[0020] Here, an object of the present invention is to provide an apparatus, a system, and a method for reliably and stably generating high-purity nitrogen using a fuel cell.

[0021] Solution to the problem

[0022] According to the present invention, a nitrogen generating device and a nitrogen generating system are provided, which include (A) a fuel cell that operates by taking in air or a gas containing nitrogen and oxygen and a fuel gas, (B) a dehumidification mechanism that reduces the moisture or water vapor content in exhaust gas extracted from the fuel cell and having a lower oxygen concentration than air, and (C) a filtering mechanism that includes a filter using fibers with different permeabilities to nitrogen and oxygen and converts the exhaust gas with reduced moisture or water vapor content into a gas with an increased nitrogen concentration. Here, the filter is preferably a filter in which a recovery rate is higher when the oxygen concentration of the gas to be filtered is lower. In addition, the dehumidification mechanism is preferably a pump unit including a water seal pump, and in this case, an adiabatic expansion chamber is preferably provided in which the exhaust gas extracted from the fuel cell is adiabatically expanded.

[0023] According to the present invention, there is also provided a nitrogen generation method, the method including the steps of supplying air or a gas containing nitrogen and oxygen and a fuel gas to a fuel cell and operating the fuel cell, extracting an exhaust gas having an oxygen concentration lower than that of air from the fuel cell, reducing the moisture or water vapor content in the extracted exhaust gas, and applying the exhaust gas having the reduced moisture or water vapor content to a filter using fibers having different permeabilities to nitrogen and oxygen and extracting the exhaust gas having an increased nitrogen concentration from the filter.

[0024] Beneficial effects of the present invention

[0025] According to the present invention, high-purity nitrogen gas can be reliably and stably generated using a fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Provide accompanying drawings, in which:

[0027] Figure 1 is a schematic diagram illustrating one embodiment of a nitrogen generating device / system according to the present invention;

[0028] Figure 2 is a diagram showing Example 1 of a nitrogen generation process according to the present invention;

[0029] Figure 3 is a diagram showing Example 1 of a nitrogen generation process according to the present invention;

[0030] Figure 4 is a diagram showing Example 1 of a nitrogen generation process according to the present invention;

[0031] Figure 5 is a graph showing Example 2 in which the recovery rate of a nitrogen filter was studied in the nitrogen generation process according to the present invention;

[0032] Figure 6 is a schematic diagram showing another embodiment of a dehumidification mechanism according to the present invention;

[0033] Figure 7 is a schematic diagram showing an embodiment of a gas-liquid separator U as a dehumidification mechanism according to the present invention;

[0034] Figure 8 is a schematic diagram showing another embodiment of the filtering mechanism according to the present invention;

[0035] Figure 9 is a schematic diagram showing another embodiment of a nitrogen generating device / system according to the present invention; and

[0036] Figure 10 is a schematic diagram showing another embodiment of a fuel cell according to the present invention. DETAILED DESCRIPTION

[0037] Embodiments for implementing the present invention will be described in detail below with reference to the accompanying drawings. In the accompanying drawings, identical components are denoted by the same reference numerals. Furthermore, components having the same structure and function may be denoted by the same reference numerals. Furthermore, the dimensional ratios within and between components in the accompanying drawings are arbitrary to facilitate understanding of the drawings.

[0038] [Nitrogen generation device / system]

[0039] Figure 1 is a schematic diagram illustrating one embodiment of a nitrogen generation device / system according to the present invention.

[0040] Figure 1 The nitrogen generating device 1 (or nitrogen generating system 1) according to one embodiment of the present invention shown in FIG. 1 includes

[0041] (A) "Fuel cell (in the fuel cell U (unit) 11)", which operates by taking in "air or a gas containing nitrogen and oxygen" and "fuel gas" (in the embodiment of the present invention, hydrogen),

[0042] (B) Dehumidification mechanism Figure 1 Gas-liquid separation U (unit) 122 and Figure 6 a water seal pump U (unit) 30 in the fuel cell, which reduces the moisture or water vapor content in the exhaust gas (tail gas) extracted from the fuel cell, which has a lower oxygen concentration than air, and

[0043] (C) Filter mechanism Figure 1The nitrogen filter U (unit) 12) in the apparatus includes a "nitrogen filter 12f" using fibers (e.g., hollow fibers) having different permeabilities to nitrogen and oxygen, and converts "exhaust gas" having a reduced moisture or water vapor content into a gas having an increased nitrogen concentration.

[0044] Here, as described above, the "nitrogen filter 12f" in (C) above is a filter using fibers having different permeabilities to nitrogen and oxygen, and the inventors of the present invention will explain the details in detail below, and it has been confirmed through experiments that in the filter using fibers, when the oxygen concentration is low, the "oxygen concentration reduction index" (unit is volume percentage (vol%), representing ml in 100 ml of medium) in the "exhaust gas" having a lower oxygen concentration than air is larger.

[0045] In this way, according to the nitrogen generating device (system) 1, by combining the "fuel cell" and the "nitrogen filter 12f" (which are very compatible in consideration of low oxygen concentration), nitrogen with a low oxygen concentration, that is, high-purity nitrogen, can be efficiently generated.

[0046] Incidentally, as will be described in detail, the inventors of the present invention have confirmed through experiments that when "exhaust gas" having an oxygen concentration of 2.5 vol% or less is applied to the "nitrogen filter 12f", "exhaust gas" can be extracted from the "nitrogen filter 12f", and the oxygen concentration of the exhaust gas is 1 / 10 or less of the result obtained when air is applied to the filter.

[0047] Furthermore, the inventors of the present invention have experimentally confirmed that the nitrogen filter 12f used in the embodiments of the present invention achieves a higher recovery rate when the oxygen concentration of the gas to be filtered is low. Therefore, when this nitrogen filter 12f is used to filter "exhaust gas" having a lower oxygen concentration than air, the recovery rate of high-purity nitrogen can be further improved. This recovery rate will be described in detail below.

[0048] Here, the "nitrogen filter 12f" is a filter using fibers with different permeabilities for nitrogen and oxygen, as described above. The inventors of the present invention have experimentally confirmed that, with this type of fiber-based filter, when the pressure of the applied "exhaust gas" is high, the oxygen concentration of the "exhaust gas" extracted from the filter is lower, resulting in higher-purity nitrogen. Therefore, in an embodiment of the present invention, a booster U (unit) 124 is provided upstream of the nitrogen filter U to increase the pressure of the applied "exhaust gas," thereby efficiently generating nitrogen with a low oxygen concentration, i.e., high-purity nitrogen.

[0049] Incidentally, as will be described in detail, it has been confirmed through experiments that it is preferable to set the pressure of the "exhaust gas" applied to the "nitrogen filter 12f" to a value exceeding a pressure threshold value, which depends on the "nitrogen filter 12f" and becomes a larger value when the flow rate of the "exhaust gas" extracted from the "nitrogen filter 12f" is larger.

[0050] Here, the expression "high purity" or "high purity" refers to a state in which the oxygen concentration in the nitrogen gas is sufficiently reduced. Specifically, the nitrogen concentration (in volume percentage (vol%), representing ml per 100 ml of the medium) in the "high purity" or "high purity" nitrogen gas produced in embodiments of the present invention can be, for example, 95 vol% or greater, or 99 vol% or greater, or can be set to 99.9 vol% or greater, or 99.99 vol% or greater, depending on the field and application in which the nitrogen gas is used.

[0051] Furthermore, the dehumidification mechanism in (B) above reduces the moisture or water vapor content in the "exhaust gas" whose relative humidity is generally about 100%, allowing the subsequent high-purification process to be carried out reliably and stably without being adversely affected by the moisture or water vapor content. Therefore, the dehumidification mechanism is an important device for effectively generating high-purity nitrogen. Here, as such an important dehumidification mechanism, it is preferable to use a water seal pump U 30 including a water seal pump, which will be referred to below. Figure 6 Describe it in detail.

[0052] [Device / system configuration]

[0053] Likewise Figure 1 As shown, the nitrogen generating device (system) 1 of the embodiment of the present invention is a device (system) comprising the following:

[0054] (a) Fuel cell U (unit) 11, which includes a "fuel cell",

[0055] (b) Natural energy power generation U (unit) 101, power storage U (unit) 101s, hydrogen generation U (unit) 102, fuel reforming and hydrogen generation U (unit) 103, hydrogen tank 104, flow control U (unit) 105, air compression U (unit) 106, air tank 107, filter U (unit) 108, and flow control U (unit) 109, arranged in front of the fuel cell 11,

[0056] (c) a drainer 111, a pressure control unit 113, a gas-liquid separation unit 114, and a hydrogen recovery unit 115 arranged at the rear of the hydrogen electrode of the fuel cell U11.

[0057] (d) a drainer 112, a pressure control unit U121, a gas-liquid separator U122, an exhaust buffer tank 123, a supercharger U124, a corrosive gas removal unit U125, a temperature control unit U126, a flow control unit U127, a nitrogen filter U12 including a nitrogen filter 12f, a supercharger U128, and a nitrogen tank 129, which are arranged at a rear position on the air electrode side of the fuel cell U11, and

[0058] (e) Overall control U (unit) 131.

[0059] The device (system) can draw in air, water, natural energy such as sunlight, and in some cases, town gas, and even commercial electricity to supply high-purity nitrogen, electricity, and heat to the outside.

[0060] That is, the nitrogen generation device (system) 1 of the embodiment of the present invention can provide the electricity and heat energy generated by the operation of the "fuel cell" to the outside in addition to the generated nitrogen, and can also be regarded as a nitrogen, electricity and heat supply device (system).

[0061] Here, the nitrogen generation device (system) 1 may include at least the fuel cell U11, components directly connected thereto, the gas-liquid separator U122, and the nitrogen filter U12, and may constitute a nitrogen generation system together with at least the natural energy power generation U101 outside the device. For example, the nitrogen generation device (system) 1 may include all components except the natural energy power generation U101, the power storage U101s, the hydrogen generation U102, the fuel reforming and hydrogen generation U103, the hydrogen tank 104, the air compression U106, the air tank 107, the supercharger U128, and the nitrogen tank 129.

[0062] The nitrogen generating device (system) 1 may include, for example, a piping joint as an exhaust gas inlet (which can be connected to an exhaust gas outlet in an externally mounted fuel cell), and may be a device (system) that inhales exhaust gas exhausted from an external fuel cell and outputs nitrogen with a reduced oxygen concentration. This may be a so-called "fuel cell-attached filter device (system)" that can be attached to a fuel cell.

[0063] That is, in this case, the nitrogen generating device (system) 1 is a device (system) including: (a) an exhaust gas inlet for receiving exhaust gas discharged from an external fuel cell, (b) a dehumidification mechanism for reducing the moisture or water vapor content in the received exhaust gas, and (c) a filter that uses fibers having different permeabilities to nitrogen and oxygen and outputs a gas with an increased nitrogen concentration by applying exhaust gas with a reduced moisture or water vapor content thereto.

[0064] Incidentally, in Figure 1 In the device / system configuration diagram, the material / energy transfer and process flow represented by the components connected by arrows can be understood as an embodiment of the nitrogen generation method according to the present invention.

[0065] Also in Figure 1 In the invention, the natural energy power generation U 101 can be a solar cell power generation unit (which includes solar cells and converts sunlight into electricity), a wind power generation unit (which uses wind power to rotate a rotor with blades, drives a power generation device and generates electricity), or a micro hydropower generation unit (which uses water flow (water power) to rotate a turbine (water turbine), drives a power generation device and generates electricity).

[0066] Furthermore, any other power generation unit can be used as the natural energy generator U 101, as long as it ultimately converts sunlight or wind / water kinetic energy into electrical energy. Furthermore, the natural energy generator U 101 can be a combination of two or more of the aforementioned power generation units. In any case, the unit for outputting generated electricity preferably includes a wattmeter that checks whether electricity is being generated at each point in time and measures the amount of generated electricity.

[0067] The power storage unit U 101s includes, for example, a secondary battery such as a lithium (Li) battery or a lead (Pb) battery, and is a storage unit that stores and accommodates the electricity supplied from the natural energy power generation unit U 101. Furthermore, the power storage unit U 101s preferably includes a storage meter that measures the amount of electricity stored at each point in time and checks whether the unit is fully charged. While electricity is supplied from the power storage unit U 101s to the hydrogen generation unit U 102 (which electrolyzes water) and the air compression unit U 106, which will be described below, commercial power may be supplied to the hydrogen generation unit U 102 and the air compression unit U 106 in place of or in addition to this electricity.

[0068] Alternatively, it is also preferable to supply electricity directly from the natural energy power generation U 101 to the hydrogen generation U 102 and air compression U 106, without using the storage U 101s, which has a predetermined limit on the storage capacity and includes expensive secondary batteries (or wherein the storage U 101s is set only as an auxiliary). In this case, natural energy is utilized by being directly converted into the chemical energy of hydrogen or the physical energy of compressed air.

[0069] Here, when the natural energy power generation U 101 generates AC (alternating current) electricity (for example, when it includes an AC generator), the AC electricity or commercial power is converted into DC (direct current) by a converter and then supplied to the power storage U 101s and the hydrogen generation U 102. In addition, if the air compression U 106 includes a DC-driven compressor 22, the electricity is converted into DC and then supplied to the air compression U 106.

[0070] In any case, the overall control U 131 can appropriately switch and control the power supply to the hydrogen generation U 102 and air compression U106 as described above while monitoring, for example, the power generation state of the natural energy power generation U 101 and the storage state of the storage U 101s.

[0071] Also in Figure 1 In the present invention, hydrogen generation U102 is a hydrogen supply unit including an electrolysis unit that can electrolyze the obtained water and generate hydrogen and oxygen using the supplied electricity. Various known electrolysis methods can be used here, and for example, electrolysis can be performed using a laminate comprising multiple electrolytic cells having a structure in which a solid polyelectrolyte membrane is interposed between a catalyst and an electrode.

[0072] The hydrogen generator U 102 preferably includes a dehumidifier to remove moisture from the generated hydrogen and oxygen. A mechanism may also be provided to return the removed moisture to the electrolysis unit for further electrolysis. Furthermore, a wattmeter is preferably provided to measure power consumption at each point in time and verify whether power is being consumed. A flow meter or barometer may also be provided to measure the amount of generated hydrogen and oxygen and verify whether hydrogen and oxygen are being generated.

[0073] The fuel reforming and hydrogen generation U 103 inhales hydrocarbon gas, such as town gas or LPG, mixes the hydrocarbon gas with steam, and generates a hydrogen-containing gas primarily composed of hydrogen (H2) from the mixed gas through a steam reforming reaction. Furthermore, it is preferred to provide a mechanism for reducing the carbon monoxide content contained in the generated hydrogen-containing gas using a CO reforming catalyst or the like, and further reducing the carbon monoxide concentration using a CO selective oxidation catalyst.

[0074] Incidentally, when a solid oxide fuel cell (SOFC) is used as the "fuel cell" of the fuel cell U 11 to be described below, waste heat from the "fuel cell" can be applied to the large amount of heat (high temperature) required for steam reforming in the fuel reforming and hydrogen generation U 103.

[0075] Here, the nitrogen generation device (system) 1 may include a hydrogen generation U102 or a fuel reforming and hydrogen generation U103 as a hydrogen (fuel) supply source, or preferably includes both of them to ensure a variety of supply sources. In addition, instead of or in addition to these supply sources, hydrogen itself may be supplied by another system / device.

[0076] The hydrogen tank 104 is a gas tank that temporarily stores and compresses (high-pressure) hydrogen supplied from the hydrogen generation unit 102 and the fuel reforming and hydrogen generation unit 103, and may include a hydrogen storage alloy bottle. Preferably, a barometer is provided in the hydrogen tank 104, and the gas pressure within the tank can be measured at each time point.

[0077] The flow control U 105 is a unit that controls the pressure and flow rate of hydrogen supplied from the hydrogen tank 104 to the fuel cell U 11. Specifically, it may include a hydrogen regulator and a hydrogen mass flow controller (or flow switch).

[0078] Here, hydrogen gas in a high-pressure state (e.g., 1.1 to 7 atm, approximately 0.11 to 0.7 MPa (megapascals)) having a pressure exceeding atmospheric pressure (1 atm, approximately 0.1 MPa) can be supplied to one side of the hydrogen electrode of the fuel cell U 11. That is, in an embodiment of the present invention, the back pressure of the "fuel cell" provided in the fuel cell U 11 can be set to, for example, atmospheric pressure or a pressure exceeding atmospheric pressure. Here, when the outlet side of the "fuel cell" is in an open state, that is, when the pressure of the exhaust gas is atmospheric pressure, the back pressure becomes 1 atm (approximately 0.1 MPa).

[0079] However, when a mass flow controller is used in the flow control U105, pressure loss generally occurs. Therefore, it is preferable to receive hydrogen gas from the hydrogen tank 104 at a pressure higher than the set pressure (back pressure), for example, by about 1 to 2 atm (about 0.1 to 0.2 MPa), adjust the pressure with a regulator, and then flow the hydrogen gas to the mass flow controller. Incidentally, it has been found through experiments that the above-mentioned pressure loss increases when the flow rate decreases (the flow rate decreases).

[0080] Also in Figure 1 , the air compression U 106 is a unit including a compressor that compresses air sucked from, for example, the atmosphere to a high pressure and supplies the air to the air tank 107. As a compression method type in the compressor, for example, various method types such as a reciprocating type, a scroll type, a screw type, a rotary type, or an oscillating type, or a combination of two or more thereof can be used.

[0081] The air tank 107 is a gas tank that temporarily accommodates and stores compressed air supplied from the air compressor U 106. Preferably, a barometer is also provided in the air tank 107, and the air pressure in the tank can be measured at each time point.

[0082] The filter U 108 is a unit that includes an air filter and an oil filter and removes fine dust, oil components, and the like from the high-pressure air supplied from the air tank 107 using these filters.

[0083] The flow control U 109 is a unit that controls the pressure and flow rate of compressed air supplied from the air tank 107 to the air electrode side of the fuel cell U11 via the filter U 108. Specifically, it may include a gas regulator and a mass flow controller (or flow switch).

[0084] Here, in an embodiment of the present invention, compressed air can also be supplied to one side of the air electrode in the fuel cell U 11 in a high-pressure state (e.g., 1.1 to 7 atm, about 0.11 to 0.7 MPa), which has a pressure exceeding atmospheric pressure (1 atm, about 0.1 MPa) (e.g., the back pressure is set to a pressure exceeding atmospheric pressure). In addition, in this case, considering the pressure loss of the mass flow controller, it is preferred that compressed air having a pressure higher than the back pressure, for example, about 1 to 2 atm (about 0.1 to 0.2 MPa), is received from the air tank 107, the pressure is adjusted by the regulator, and then the compressed air is caused to flow to the mass flow controller, which is the same as in the above-mentioned hydrogen.

[0085] Also in Figure 1 In the example, the fuel cell U 11 is a unit that includes a “fuel cell” and extracts and outputs exhaust gas having an oxygen concentration lower than that of air, electricity, heat, and water (steam) from the “fuel cell”.

[0086] Of course, the fuel cell U 11 can be used by setting the back pressure of the "fuel cell" to atmospheric pressure (1 atm, about 0.1 MPa). However, as a preferred embodiment, the fuel cell U 11 may include a "fuel cell"

[0087] (a) wherein a back pressure exceeding atmospheric pressure is set (e.g., 1.1 to 7 atm, approximately 0.11 to 0.7 MPa),

[0088] (b) it receives hydrogen having a pressure exceeding atmospheric pressure (e.g., 1.1 to 7 atm, about 0.11 to 0.7 MPa) from flow control U 105 and receives compressed air having a pressure exceeding atmospheric pressure (e.g., 2 to 7 atm) from flow control U 109, and then starts operating, and

[0089] (c) It discharges exhaust gas having a pressure exceeding atmospheric pressure (eg, 1.1 to 7 atm, approximately 0.11 to 0.7 MPa).

[0090] Here, the “fuel cell” may have a known configuration and may have a structure in which, for example, a plurality of cells having a structure in which an electrolyte is placed between a hydrogen electrode (fuel electrode, positive electrode, or anode) and an air electrode (oxygen electrode, negative electrode, or cathode) are stacked (laminated) with a separator therebetween.

[0091] Fuel cells include polymer electrolyte fuel cells (PEFCs), solid oxide fuel cells (SOFCs), phosphoric acid fuel cells (PAFCs), and molten carbonate fuel cells (MCFCs). SOFCs offer high power generation efficiency, generally operate at temperatures of approximately 700°C to 1,000°C, and can supply relatively high-temperature exhaust gas. As mentioned above, when hydrogen is generated from town gas, for example, using fuel reforming and hydrogen generation (U 103), SOFCs can supply the large amounts of heat required for steam reforming. PEFCs are also used in many fuel cell vehicles, for example, because they operate at relatively low temperatures and can reduce cell size.

[0092] In the case of adopting PEFC, for example, a JARI-type fuel cell developed by the Japan Automobile Research Institute (JARI) Research and Development can be used as the "fuel cell" in the fuel cell U 11. The JARI-type fuel cell has a structure in which pressure can be applied to the inside of the cell by increasing back pressure, and in addition, all exhaust gas with high back pressure can be recovered.

[0093] Furthermore, as a "fuel cell," a fuel cell with a maximum output of, for example, greater than 10 kW (e.g., fuel cells manufactured by PowerCell, a Swedish fuel cell manufacturer) can be used. For example, in a PowerCell fuel cell with 96 cells and a maximum output of 12.9 kW, the hydrogen flow rate and air flow rate required to output 10 kW of electricity are 150 L / min (liters per minute) and 500 L / min, respectively. In this case, the flow rate of nitrogen contained in the exhaust gas is 400 L / min. Furthermore, the flow rate of water vapor contained in the exhaust gas is 150 L / min, which, expressed as water, is 5.3 L / h (liters per hour).

[0094] Incidentally, in order to reduce such a large amount of water vapor content / moisture exhausted from the "fuel cell" and to reliably and stably perform the subsequent nitrogen generation process, a dehumidification mechanism ( Figure 1 Gas-liquid separation in U 122 and Figure 6 The water seal pump U30 in the dehumidification mechanism is preferably provided to the outside in the form of pure water or high-purity water. Furthermore, for this "fuel cell," both air and hydrogen are preferably introduced via a humidification device (not shown) to reduce the decrease in proton conductivity of the electrolyte membrane (due to insufficient wettability), which would result in heat loss in the fuel cell reaction.

[0095] In the embodiment of the present invention, the pressure in the "fuel cell", that is, the back pressure, is regulated and controlled by the back pressure regulating valve of the pressure control U 113 and the back pressure regulating valve of the pressure control U 121 to be described below. Here, it is preferred to control

[0096] (a) The back pressure on the hydrogen electrode side, which is mainly regulated by the back pressure regulating valve of pressure control U113, and

[0097] (b) The back pressure on the air electrode side is mainly regulated by the back pressure regulating valve of pressure control U121.

[0098] Make them substantially the same. In practice, if there is a difference of approximately 0.1 atm (0.01 MPa) between the two back pressures, a small amount of gas may leak from the fuel cell. On the other hand, experiments have found that if the two back pressures are the same, there is no problem even at relatively high back pressures. In particular, when the fuel cell is a PEFC, since the electrolyte membrane is relatively thin, it is more preferable to make the two back pressures the same.

[0099] Furthermore, the fuel cell U 11 including the above-mentioned "fuel cell" preferably includes a measurement system / sensor group capable of measuring the following:

[0100] (a) the flow rate, pressure and / or temperature of hydrogen and air entering the “fuel cell”,

[0101] (b) the flow rate, pressure and / or temperature of the exhaust gases and water vapor / moisture from the “fuel cell”, and

[0102] (c) Complex impedance between the hydrogen electrode and the air electrode of the “fuel cell”.

[0103] Furthermore, the operation of the "fuel cell" is preferably controlled by an overall control U 131 which has received information from the measuring system / sensor group.

[0104] As an example of simple control, preferably, a machine learning model is constructed (using, for example, a deep neural network (DNN) algorithm), wherein (b) and (c) above are explanatory variables, and (a) above is a target variable. Using the constructed model, the flow rate, pressure, and / or temperature of the hydrogen and air supplied to the "fuel cell" can be adjusted so that the "fuel cell" produces the desired output. In addition, when the complex impedance value in (c) above deviates from a predetermined allowable range, control is preferably performed, such as stopping the hydrogen supply and stopping the "fuel cell."

[0105] In addition, in the fuel cell U 11, a heat exchanger that circulates a heat exchange medium such as water can be placed inside or around the "fuel cell". The heat exchanger preferably extracts heat from the "fuel cell" that is operating and generating heat, and transfers the heat to the outside of the unit. Examples of heat exchangers that can be used include multi-tubular heat exchangers such as shell and tube heat exchangers and plate heat exchangers such as brazed plate heat exchangers (commercially available from Alfa Laval AB).

[0106] Furthermore, instead of a heat exchanger, a heat transfer system connecting a conductive membrane in the fuel cell and a heat pipe can be used to extract heat directly from the fuel cell to the outside. In any case, through this heat exchange / conduction mechanism, the cell temperature of the fuel cell can be controlled to a predetermined temperature (e.g., 80°C) or lower, and proper operation of the fuel cell can be maintained. Here, when water (cooling water) is used as the heat exchange medium, it is preferred to remove ions (cations and anions) from the circulating cooling water using an ion exchanger.

[0107] The heat transferred in this manner through the heat exchange medium or heat pipe can be utilized not only by supplying it to the outside, but also by supplying it to the inside of the system. In an embodiment of the present invention, the heat can be supplied to the exhaust buffer tank 123, which will be described below, and the heat can increase the temperature of the exhaust gas supplied to the nitrogen filter U12 to a high temperature (e.g., 45°C). Of course, when the exhaust gas temperature is sufficiently high, such heat treatment in the exhaust buffer tank 123 is unnecessary.

[0108] Furthermore, this heat exchange medium or heat pipe can be used to transfer heat to the fuel reforming and hydrogen generation unit (U103), supplementing the heat required for steam reforming. Furthermore, the heat from the hydrogen generation unit (U102) can be used to convert water to be electrolyzed into steam or to raise the water temperature, thereby improving the efficiency of hydrogen generation during electrolysis.

[0109] Here, in this case, in order to achieve the desired hydrogen generation efficiency and maintain it stable, it is preferable to monitor the temperature of the electrolytic cell with an installed temperature sensor and control the electrolysis operation through the overall control U 131. In addition, it is possible to increase the voltage applied between the electrodes and perform an electrolysis process that does not use an electrolyte and does not require electrolyte monitoring or maintenance.

[0110] Furthermore, for example, the interior of the facility in which the device (system) 1 is installed can be heated using high-temperature medium from a heat exchanger or a high-temperature medium that has received heat transferred via a heat pipe. For example, this high-temperature medium is placed in a cooling column (cooling tower) to reduce the temperature, and the low-temperature medium is used to generate cold air in the condenser / evaporator and air conditioner, thereby cooling the interior of the facility. Furthermore, in this case, the nitrogen generation device (system) 1 can also utilize electricity from a "fuel cell" to assist in the operation of these air conditioning devices, and thus, it can also serve as an energy-saving device (system) in the facility.

[0111] As another embodiment of the fuel cell U 11, two or more "fuel cells" are connected in series, sequentially drawing in exhaust gas from the previous fuel cell and using it for the cell reaction. This allows for easy extraction of exhaust gas with a low oxygen concentration, for example, 2.5 vol% or less. This fuel cell configuration, invented by the present inventors, is disclosed in Japanese Patent Application Publication No. 2019-129110.

[0112] Also in Figure 1 In the example, drainers 111 and 112 are respectively provided at the fuel channel outlet (on the hydrogen electrode side) and the air channel outlet (on the air electrode side) of the "fuel cell" in the fuel cell U11. These drainers recover water produced by condensation of water vapor contained in the exhaust gas (generally having a relative humidity of approximately 100%). Thus, the adverse effects on the cell reaction caused by the so-called flooding phenomenon can be reduced. Furthermore, the water recovered in this manner can be sent to the hydrogen generation U102 and reused as a hydrogen generation material.

[0113] Here, by setting the back pressure of the "fuel cell" to a value exceeding atmospheric pressure (e.g., 2 to 7 atm, approximately 0.2 to 0.7 MPa), the dew point can be increased, the amount of water falling into the drains 111 and 112 can be increased, and the dehumidification effect can be improved. The drains 111 and 112 preferably have an automatic drain function that automatically drains water to the outside when a predetermined amount of water accumulates.

[0114] Pressure control U 113 is a unit that returns the hydrogen gas dehumidified by drainer 111 to the fuel channel inlet (on the hydrogen electrode side) of the "fuel cell" (e.g., at the downstream stage of flow control U 105) via a hydrogen mixer, for example, while maintaining the back pressure of the "fuel cell." Specifically, pressure control U 113 includes a back pressure regulating valve and a pressure gauge, and controls the pressure in the "fuel cell," particularly the pressure (back pressure) on the hydrogen electrode side, by adjusting the back pressure regulating valve.

[0115] The gas-liquid separator U114 is a unit that removes residual water vapor and moisture from the exhaust gas discharged from the fuel channel outlet (on the hydrogen electrode side) via the drain 111 and pressure control U113. Specifically, a dehumidification device including a dehumidifier, a dehumidification device with a pressurizing mechanism, a gas-liquid separator, and / or a dry filter can be used to remove water vapor and moisture. Here, as a dehumidifier, a dehumidifier containing silica gel and / or zeolite can be used. And as a gas-liquid separator, a gravity separation type, a centrifugal separation type, a demisting pad type, a wing-type separation type, a gas pressure separation coalescer type, etc. can be used.

[0116] The hydrogen recovery unit (U115) extracts unreacted residual hydrogen from the exhaust gas discharged from the fuel channel outlet (on the hydrogen electrode side) using a known hydrogen filter or actuator and reuses it. For example, the extracted hydrogen can be returned to the hydrogen mixer located after the flow control unit (U105). Alternatively, the gas from which hydrogen has been extracted can be discharged externally.

[0117] The pressure control unit 121 is a unit that sends the exhaust gas dehumidified by the drain 112 (on the air electrode side) to the gas-liquid separation unit 122 while maintaining the back pressure of the "fuel cell." Specifically, like the pressure control unit 113, the pressure control unit 121 includes a back pressure regulating valve and a pressure gauge, and controls the pressure in the "fuel cell," particularly the pressure (back pressure) on the air electrode side, by adjusting the back pressure regulating valve.

[0118] Also in Figure 1 In the present invention, the gas-liquid separator U 122 is a unit that removes residual water vapor and moisture from the exhaust gas discharged from the air channel outlet (on the air electrode side) via the drain 112 and the pressure control unit 121. Specifically, the gas-liquid separator U 122 removes water vapor and moisture using a dehumidification device including a dehumidifier, a dehumidification device with a pressurizing mechanism, or a gas-liquid separator. As a standard, the gas-liquid separator U 122 can reduce the relative humidity in the exhaust gas to 60% or less, and more preferably 30% or less.

[0119] In addition, as will be referenced below Figure 7 As described in detail, the gas-liquid separation U 122 may be a dry filter unit using a dry filter 122f ( Figure 7 As another preferred embodiment, reference will be made to Figure 6As described in detail, the water seal pump U 30 including the water seal pump 301 can be used as a dehumidification mechanism instead of the gas-liquid separator U 122. In addition, the gas-liquid separator U 122 can be a pump unit including a dry vacuum pump. A dry vacuum pump is a vacuum pump that does not use oil or liquid in the vacuum chamber and can be used to discharge, for example, water vapor. As such a dry vacuum pump, for example, an air-cooled dry vacuum pump NeoDry 60E (commercially available from KASHIYAMA Industries, Ltd.) can be used. The air-cooled dry vacuum pump has a structure in which a pair of multi-stage Roots rotors rotate in a non-contact manner to compress and discharge gas.

[0120] The exhaust buffer tank 123 is a gas tank that temporarily holds and stores the exhaust gas introduced from the gas-liquid separator U122. The exhaust gas is introduced into the exhaust buffer tank 123 until the pressure reaches the same level as the back pressure (e.g., 1.1 to 7 atm, approximately 0.11 to 0.7 MPa). In order to allow the exhaust gas to flow into the nitrogen filter U12 described below at the desired pressure (e.g., 7 atm, approximately 0.7 MPa), the flow rate of the exhaust gas to the exhaust buffer tank 123 is preferably set to be equal to or greater than the desired introduction flow rate for the nitrogen filter U12.

[0121] Incidentally, when the "fuel cell" stops, the pressure in the pipe connected to the exhaust gas buffer tank 123 returns to, for example, atmospheric pressure. Therefore, the exhaust gas buffer tank 123 preferably includes a check valve to prevent exhaust gas from flowing back into the "fuel cell." Furthermore, it is preferable to provide a barometer in the exhaust gas buffer tank 123 so that the gas pressure within the tank can be measured at each point in time.

[0122] Furthermore, in the exhaust buffer tank 123, the exhaust gas in the tank is preferably set to a temperature higher than room temperature (e.g., 30° C. to 45° C.) using a "heating mechanism" (which can be heat-treated using the heat generated by the "fuel cell" in the fuel cell U 11). Thus, exhaust gas having a temperature suitable for nitrogen filtration processing can be supplied to the nitrogen filter 12 f of the nitrogen filter U 12, which will be described below.

[0123] The aforementioned heat exchanger or separator and heat pipe connection system can be used as the "heating mechanism." This allows for efficient utilization of the heat from the "fuel cell" to achieve appropriate nitrogen filtration without the use of energy-consuming devices such as electric heaters. However, this heating mechanism is unnecessary when the exhaust gas introduced into the exhaust buffer tank 123 is sufficiently hot.

[0124] The supercharger U 124 further increases the pressure of the exhaust gas (for example, to a pressure of 7 atm (about 0.7 MPa)), the exhaust gas is extracted from the "fuel cell" of the fuel cell U 11 and the moisture or water vapor content therein is reduced, and the gas is supplied to the nitrogen filter U 12. As the supercharger U 124, a known compression pump such as Bebicon (registered trademark) POD-7.5VNB (commercially available from Hitachi Industrial Equipment Systems Co., Ltd.) can be used. Alternatively, a known boost valve such as a boost valve VB11A or VBA42 for inert gas (commercially available from SMC Corporation) can be used. In addition, a pressure gauge for monitoring the increased exhaust gas pressure is preferably provided.

[0125] Most known boost valves are air-driven. In this case, a portion of the compressed air supplied to the "fuel cell," namely, compressed air drawn from the air tank 107, can be used as the supply gas to drive the boost valve. This eliminates the burden of driving the boost valve, such as additional power consumption. Furthermore, a boost compressor is preferably used as the supercharger U 124.

[0126] Incidentally, as described above, of course, when the pressure of the exhaust gas from the exhaust buffer tank 123 is sufficiently high (for example, 7 atm (about 0.7 MPa)), the supercharger U 124 is unnecessary. In addition, although careful handling is required, hydrogen extracted from the hydrogen tank 104 can be used as the supply gas.

[0127] Also in Figure 1 Among them, the corrosive gas removal U 125 is such a unit that can remove or reduce at least one of sulfides, chlorides, hydrocarbons, fluorides and strong alkaline compounds from the exhaust gas (extracted from the "fuel cell") to be applied to the nitrogen filter 12f of the nitrogen filter U 12.

[0128] For example, when hydrogen is generated from town gas or the like using fuel reforming and hydrogen generation U103 and used as fuel for a "fuel cell," various gas components other than hydrogen, such as hydrogen sulfide, sulfurous acid gas, hydrocarbon gases such as methane gas, ammonia, and formaldehyde, are mixed into the exhaust gas. Furthermore, when an SOFC is used as a "fuel cell," nitrogen in the air may combine with oxygen in a high-temperature atmosphere of approximately 800°C, potentially generating nitrogen oxides (NOx). These gases not only become impurities in the final nitrogen product but also pose a risk of adversely affecting the fibers (hollow fibers) of the nitrogen filter 12f.

[0129] Therefore, the corrosive gas etc. removal U 125 includes, for example, an activated carbon filter and plays a role in removing impurity gases in the exhaust gas or reducing the impurity gases as much as possible. As a standard, the corrosive gas etc. removal U 125 preferably reduces the concentration of hydrocarbon gas to 0.013 mg / Nm 3 (0.01 ppm wt) or less, and preferably reduce the concentration of strong acid gases such as hydrogen sulfide, sulfurous acid gas, hydrogen chloride and fluorine, and strong alkaline gases such as amines, ammonia and caustic soda to the detection limit or less in a predetermined detection method.

[0130] In addition, if Figure 1 As shown, it is preferable to install a mist filter and a dust filter before or after the U125 removal process for corrosive gases, etc. The mist filter is a filter that removes or reduces mist such as water mist, solvent mist, and oil mist from the exhaust gas. As a standard, the mist filter preferably reduces the concentration of residual oil from these mists to 0.01 mg / Nm 3 (0.008 ppmwt) or less. On the other hand, a dust filter is a filter that removes or reduces dust in exhaust gas. As a standard, a dust filter preferably eliminates almost all particles having a particle size of 0.01 μm or larger.

[0131] The temperature control U 126 is a unit that includes, for example, an electric heater and brings the temperature of the sucked exhaust gas close to or equal to a suitable temperature preset based on the characteristics of the nitrogen filter 12f and supplies the exhaust gas having its temperature adjusted to the nitrogen filter U 12. As a preferred embodiment, the temperature control U 126 can receive heat supplied by the fuel cell U 11 via a heat exchanger and use the heat for temperature adjustment, and can also adjust the temperature of the exhaust gas using electricity supplied by the fuel cell U 11.

[0132] Incidentally, in the UBE N2 separator NM-B01A (commercially available from Ube Industries, Ltd.), which can be used as the nitrogen filter 12f described in detail below, it is proposed that the filtering effect becomes stronger when the temperature of the introduced gas is 30°C to 45°C (higher than room temperature (25°C)). In this case, when the exhaust gas temperature from the "fuel cell" is higher than room temperature (25°C), a strong filtering effect can be exhibited without using the temperature control U126, and therefore, the amount of electricity consumed for temperature regulation can be reduced.

[0133] Furthermore, it has been demonstrated that, in nitrogen filter 12f using fibers having different permeabilities for nitrogen and oxygen, the recovery rate significantly decreases when the temperature of the introduced exhaust gas is high. Therefore, based on the nitrogen output performance set by the system of the present invention, in order to maintain a predetermined recovery rate, the exhaust gas temperature can be maintained approximately the same as the temperature in exhaust buffer tank 123 without using temperature control unit U126.

[0134] Also in Figure 1 In the embodiment, the nitrogen filter U 12 is a unit that applies the exhaust gas controlled by the flow control U 127 to the nitrogen filter 12f using fibers having different permeabilities to nitrogen and oxygen, and extracts the exhaust gas with an increased nitrogen concentration, that is, the high-purity nitrogen in the embodiment of the present invention, from the nitrogen filter 12f.

[0135] Specifically, in an embodiment of the present invention, the nitrogen filter U12 includes

[0136] (a) Nitrogen filter 12f,

[0137] (b) a filter input and output section that introduces exhaust gas to be applied to the nitrogen filter 12f and extracts exhaust gas having an increased nitrogen concentration from the nitrogen filter 12f, and

[0138] (c) A filter purge section which extracts a gas (hereinafter referred to as filter exhaust gas) containing oxygen molecules separated from nitrogen molecules (in the exhaust gas) by the nitrogen filter 12f from the exhaust gas extracted in (b) above.

[0139] Specifically, as the nitrogen filter 12f, a hollow fiber filter using a polymer fiber material that preferentially permeates oxygen molecules over nitrogen molecules can be used. For example, the UBE N2 separator NM-B01A (commercially available from Ube Industries, Ltd.) using polyimide hollow fibers can be used. The mechanism of the N2 separator is that when high-pressure exhaust gas flows through the hollow fiber, oxygen molecules selectively permeate the hollow fiber membrane, and high-purity nitrogen is ultimately extracted from the outlet of the hollow fiber.

[0140] Of course, the nitrogen filter 12f is not limited to the above separators. For example, UBE N2 separator NM series separators (commercially available from Ube Industries, Ltd.), SEPURAN N2 membrane modules (commercially available from Daicel-Evonik Ltd.), and also selective nitrogen filters (commercially available from Daicel-Evonik Ltd.) can be used as the nitrogen filter 12f.

[0141] Here, in such a nitrogen filter 12f, the relationship between the following is:

[0142] (a) the oxygen concentration of the introduced exhaust gas (introduction oxygen concentration), the pressure of the introduced exhaust gas (introduction pressure), and the flow rate of the exhaust gas at the outlet of the filter 12f (outlet flow rate), and

[0143] (b) Oxygen concentration of exhaust gas at the outlet of filter 12f (outlet oxygen concentration) and recovery rate of filter 12f

[0144] Will be used below Figures 2 to 5 The actual example shown will be described in detail, and among them, the various conditions for obtaining high-purity nitrogen will also be described.

[0145] Here, the outlet flow rate in (a) above can be measured with a flow meter installed on the outlet side of the nitrogen filter U12 and controlled by the flow control U127 described below. In addition, the outlet oxygen concentration in (b) above can also be measured with an oxygen concentration meter installed on the outlet side of the nitrogen filter U12. Of course, the flow control U127 is preferably installed immediately behind the oxygen concentration meter and the flow meter.

[0146] In addition, in an embodiment of the present invention, based on the outlet oxygen concentration value measured by the oxygen concentration meter, the total control U131 controls the back pressure regulating valve of the pressure control U121 to adjust the back pressure of the "fuel cell", for example, controls the mass flow controller of the flow control U127 to adjust the exhaust gas flow rate with respect to the filter, for example, and thereby the supply of high-purity nitrogen with a desired extremely low oxygen concentration can be achieved.

[0147] Also in Figure 1 In the embodiment, the flow control unit U127 is a unit that controls the flow rate of the exhaust gas with an increased nitrogen concentration (i.e., high-purity nitrogen in the embodiment of the present invention) generated by the nitrogen filter U12, and feeds the nitrogen gas into the nitrogen tank 129 via the booster U128. That is, as described above, it is a unit that controls the outlet flow rate (f_out) of the nitrogen filter 12f. Specifically, it can include a gas regulator and a mass flow controller (or flow switch).

[0148] In an embodiment of the present invention, the booster U 128 is a unit that further increases the pressure of the high-purity nitrogen gas whose flow rate is controlled by the flow control U 127 (for example, to a pressure of 8 to 15 atm (about 0.8 to 1.5 MPa)), feeds the gas into the nitrogen tank 129, and enables the nitrogen tank 129 to accommodate and store a larger amount of high-purity nitrogen gas. As the booster U 128, for example, a boost valve or a boost compressor can be used. The booster Bebicon (registered trademark) OBB-7.5GP (commercially available from Hitachi Industrial Equipment Systems Co., Ltd.) capable of increasing the pressure to 10 atm (about 1.0 MPa) or higher can be used. In addition, a pressure gauge for monitoring the pressure increase is preferably provided.

[0149] The nitrogen tank 129 temporarily accommodates and stores high-purity nitrogen gas supplied from the nitrogen filter U 12 via the booster U 128, and serves as a nitrogen supply interface through which high-purity nitrogen gas is stably supplied to the outside under the control of, for example, the main control U 131. Preferably, a barometer is also provided in the nitrogen tank 129, so that the gas pressure in the tank can be measured at each time point.

[0150] Here, without using the nitrogen tank 129 (and the booster U 128) as a nitrogen supply interface, the generated nitrogen can be directly supplied to the outside from the nitrogen filter U 12 via a predetermined flow control device. For example, in the case where the supply destination is a welding device, directly supplied high-purity nitrogen with a temperature at least higher than room temperature (25°C) is more suitable for use as a welding atmosphere because the heat required for a higher temperature atmosphere can be saved.

[0151] The overall control U 131 is a controller that can communicate with the main components including the above-mentioned fuel cell U 11 and nitrogen filter U12, and preferably all components (including, for example, the water seal pump U 30 ( Figure 6 )) Communicates via a wired or wireless communication network, receives measurement quantities output from the measuring unit / sensor of each component, such as pressure, gas flow rate, temperature, nitrogen concentration, oxygen concentration, hydrogen concentration, and whether there is hydrogen leakage, monitors appropriately, and supervises and controls each component.

[0152] For example, preferably, the general control U 131 includes a processor and a memory, a nitrogen generation system monitoring / control program for monitoring / controlling each component is installed and stored in the memory, and the program is executed by the processor.

[0153] Here, the control performed by the overall control U 131 includes adjusting and controlling the pressure, gas flow rate, temperature, nitrogen concentration, oxygen concentration, and hydrogen concentration in each component and between components. In particular, it is preferred to control the back pressure of the "fuel cell" of the fuel cell U 11 and control the balance between the back pressure on the hydrogen electrode side and the back pressure on the air electrode side.

[0154] In addition, it is preferred that the overall control U 131 monitors the temperature of the "fuel cell" of the fuel cell U 11 (cell temperature), the temperature of the exhaust gas introduced into the nitrogen filter 12f of the nitrogen filter U 12, and also the temperature of the hydrogen generation U 102, and appropriately controls the fuel cell reaction, the filtration operation, and also the hydrogen generation (electrolysis) reaction in the nitrogen generation device (system) 1. In addition, the occurrence of hydrogen leakage in each component and between components is monitored, and when it is determined that a problem has occurred, the overall control U 131 preferably sends an alarm including information about the location of the hydrogen leak to the outside.

[0155] [Example 1]

[0156] Figures 2 to 4 FIG. 1 is a diagram showing Example (Application Example) 1 of the nitrogen generation process according to the present invention.

[0157] The measurement and analysis results are shown in Figures 2 to 4 In Example 1, UBEN2 separator NM-B01A (commercially available from Ube Industries, Ltd.) was used as the nitrogen filter 12f ( Figure 1 ), air having an oxygen concentration of 20.8 vol% and three mixed gases, which are gases in which nitrogen and oxygen are mixed and have oxygen concentrations of 10.3 vol%, 5.1 vol% and 1.1 vol%, were respectively introduced into the nitrogen filter 12f, and the following were measured:

[0158] (a) the oxygen concentration of the introduced gas (introduced oxygen concentration c_in_O2 (vol%)), the pressure of the introduced gas (introduced pressure p_in (atm)), and the flow rate of the exhaust gas at the outlet of the nitrogen filter 12f (outlet flow rate f_out (L / min)), and

[0159] (b) oxygen concentration of the gas at the outlet of the nitrogen filter 12f (outlet oxygen concentration c_out_O2 (ppm vol)),

[0160] And study the relationship between (a) and (b) above.

[0161] Here, the oxygen concentrations of 10.3 vol%, 5.1 vol%, and 1.1 vol% in the introduced gas are values that may occur in the exhaust gas of an actual “fuel cell”.

[0162] Figure 2 (A), 2(B) and 2(C) are graphs showing the relationship between the introduced oxygen concentration c_in_O2 and the outlet oxygen concentration c_out_O2 under the conditions that the outlet flow rate f_out is 2.0 L / min, 1.5 L / min and 1.0 L / min, respectively.

[0163] From these figures, it should be understood that

[0164] (a) When the introduced oxygen concentration c_in_O2 is low,

[0165] (b) When the introduction pressure p_in is large, and

[0166] (c) When the outlet flow rate f_out is low, the outlet oxygen concentration c_out_O2 is low and higher purity nitrogen is output from the nitrogen filter 12f.

[0167] For example, when the introduced oxygen concentration c_in_O2 is set to 1.1%, the introduced pressure p_in is set to 7.0 atm (about 0.7 MPa), and the outlet flow rate f_out is set to 1.0 L / min, the outlet oxygen concentration c_out_O2 is 325 ppm (0.0325 vol%) (although it is Figure 2 (C)). It was found that under the same conditions of introduced oxygen concentration and introduction pressure as above, when the outlet flow rate f_out was set to a relatively low 0.75 L / min, the outlet oxygen concentration c_out_O2 was a very low value of 190 ppm (0.0190 vol%), and high-purity nitrogen gas with an extremely low oxygen concentration was obtained. Furthermore, it was confirmed experimentally that this result trend remained almost unchanged even when the temperature of the gas introduced into the nitrogen filter 12f was 40°C and 50°C.

[0168] <Outlet flow rate and outlet oxygen concentration>

[0169] First, a more specific relationship between the outlet flow rate f_out and the outlet oxygen concentration c_out_O2 will be described. Figure 2 The data in Figures (A) to 2(C) are used to deduce the relationship between them, which is expressed by the following equation.

[0170] (1)(c_out_O2)=C·(f_out) a

[0171] Here, the coefficient C of item (a) has a positive value and has a smaller value when the introduced oxygen concentration c_in_O2 is low and the introduced pressure p_in is large. For example, when the introduced oxygen concentration c_in_O2 is 1.1% and the introduced pressure p_in is 7.0 atm (about 0.7 MPa), the C value is 319 (ppm), which is a very small value. On the other hand,

[0172] (b) When the introduction pressure p_in is 4.0 atm (about 0.4 MPa), the power coefficient 'a', which is almost independent of the introduction oxygen concentration c_in_O2, is about 1.6. Furthermore, when the introduction pressure p_in is 7.0 atm (about 0.7 MPa), the power coefficient is about 2.0, which becomes larger as the introduction pressure p_in increases.

[0173] Therefore, it should be understood that, in any case, when the outlet flow rate f_out is low, the outlet oxygen concentration c_out_O2 can be lower, that is, high-purity nitrogen gas with a lower oxygen concentration is obtained. Here, since the power coefficient 'a' is determined only by the inlet pressure p_in, the contribution mechanism of the outlet flow rate to the outlet oxygen concentration is considered to be dynamic relative to the fiber state of the filter 12f, which is determined by the inlet pressure of the filter.

[0174] <Introduced Oxygen Concentration and Filtration Effect>

[0175] Next, use Figure 3 The analysis results shown will describe the relationship between the introduced oxygen concentration c_in_O2 and the filtering effect of the nitrogen filter 12f (ie, the degree of the oxygen concentration reducing effect).

[0176] Figure 3 3(A), 3(B), and 3(C) are graphs showing the relationship between the introduced oxygen concentration c_in_O2 and the oxygen concentration reduction index under the conditions of the outlet flow rate f_out being 2.0 L / min, 1.5 L / min, and 1.0 L / min, respectively. Here, the four graphical curves shown in each of these figures are power approximation curves with respect to data points when the introduction pressure p_in is 4.0 atm (about 0.40 MPa), 5.0 atm (about 0.51 MPa), 6.0 atm (about 0.61 MPa), and 7.0 atm (about 0.71 MPa).

[0177] Here, when air having an oxygen concentration of 20.8 vol% is introduced into the nitrogen filter 12f, the outlet oxygen concentration is set to c_out_O2 (air), and the oxygen concentration reduction index is calculated by the following formula.

[0178] (2) (Oxygen concentration reduction index) = c_out_O2 (air) / c_out_O2

[0179] That is, the oxygen concentration reduction index is an index showing the extent to which the absolute oxygen concentration is reduced by filtration, that is, the magnitude of the filtration effect (relative to the case of air), based on the results of the introduced air.

[0180] according to Figure 3 (A), 3(B) and 3(C) found that

[0181] (a) The oxygen concentration reduction index is large when the introduced oxygen concentration c_in_O2 is low, and in particular, the increase rate of the index increases sharply when the introduced oxygen concentration c_in_O2 exceeds 10 vol%,

[0182] (b) The oxygen concentration reduction index does not show a significant dependence on the introduction pressure p_in, and there is also

[0183] (c) The oxygen concentration reduction index does not show a significant dependence on the outlet flow rate f_out.

[0184] Here, the introduced oxygen concentration c_in_O2 of 10 vol% (at which time the exponential growth rate in (a) above begins to increase rapidly) is roughly equivalent to the oxygen concentration in the exhaust gas of a "fuel cell" having an oxygen utilization rate of 50%.

[0185] Furthermore, based on the above analysis results, it should be understood that, for example, when attempting to find a filtration condition that results in an oxygen concentration reduction index of 10, i.e., a filtration effect multiplied by 10, i.e., one digit higher (compared to the case of air), the introduced oxygen concentration c_in_O2 should be 2.5 vol% or lower, regardless of the set values of the introduction pressure p_in and the outlet flow rate f_out. Here, the c_in_O2 value of 2.5 vol% is the average of the introduced oxygen concentration values at which the oxygen concentration reduction index in the four power approximation curves in each figure is 10. Incidentally, the horizontal axis intercept of the tangent line near 1.1 vol% of c_in_O2 for each curve in each figure is a value close to 2.5 vol% (= c_in_O2).

[0186] Therefore, in Figure 1 In the nitrogen generating device (system) 1 of the embodiment shown, when exhaust gas having an oxygen concentration of 2.5 vol% or less is applied to the nitrogen filter 12f, exhaust gas having an oxygen concentration of 1 / 10 or less can be extracted from the filter 12f compared to the result obtained by introducing air. Here, it was confirmed by experiments that even when the temperature of the gas introduced into the nitrogen filter 12f was 40°C and 50°C, the above-mentioned Figure 3 The results shown in the figure are basically consistent, especially in the low oxygen concentration area.

[0187] <Inlet Pressure and Outlet Oxygen Concentration>

[0188] Next, we will use Figure 4 The analysis results shown describe the relationship between the inlet pressure p_in and the outlet oxygen concentration c_out_O2.

[0189] Figure 4 is a graph showing the relationship between the introduction pressure p_in and (secondary coefficient) / (primary coefficient), which is in the case corresponding to Figure 2 The four polynomial (second-order) approximations for the four graphical curves in each of Figures (A) to 2(C) are derived by taking the ratio of the quadratic coefficient to the linear coefficient.

[0190] exist Figure 2 In the graphs shown in (A) to 2(C), four graphs are shown that indicate the relationship between the introduced oxygen concentration c_in_O2 and the outlet oxygen concentration c_out_O2 when the introduced pressure p_in is 4.0 atm (about 0.40 MPa), 5.0 atm (about 0.51 MPa), 6.0 atm (about 0.61 MPa), and 7.0 atm (about 0.71 MPa). And near each graph, a polynomial (second-order) approximation formula corresponding to the graph is shown. For example, in Figure 2In the graph (C), near the curve of p_in=7.0atm (and f_out=1.0L / min), the polynomial approximation

[0191] (3)y=6.6246x 2 +161.96

[0192] Here, it is shown that y is c_out_O2 (vol %) and x is c_in_O2 (vol %).

[0193] In this formula, the quadratic coefficient is 6.6246, and the linear coefficient is 161.96.

[0194] In this way, it is found that the introduced oxygen concentration c_in_O2 not only contributes proportionally to the outlet oxygen concentration c_out_O2 as a linear term, but also has an impact as a quadratic term. In other words, even if the introduced oxygen concentration c_in_O2 is reduced to 1 / N, the outlet oxygen concentration c_out_O2 does not simply decrease to 1 / N, but rather the quadratic term of the introduced oxygen concentration c_in_O2 has an impact on the outlet oxygen concentration c_out_O2.

[0195] Figure 4 The graph of is obtained by: Figure 2 In each graphical curve of Figures (A) to 2(C), (quadratic coefficient) / (primary coefficient) is calculated, which is the ratio of the quadratic coefficient to the primary coefficient as described above, and then these calculated values are plotted, where the vertical axis represents (quadratic coefficient) / (primary coefficient) and the horizontal axis represents the introduced pressure p_in.

[0196] according to Figure 4 It is found that three graphical curves with outlet flow rates f_out of 1.0 L / min, 1.5 L / min and 2.0 L / min are obtained ( Figure 4 ), and therefore Figure 4 The plot points in can be approximated by a linear approximation determined for each outlet flow rate.

[0197] According to these graphs (straight lines), when the inlet pressure p_in is large and the outlet flow rate f_out is low, (quadratic coefficient) / (primary coefficient) is large. Therefore, it is found that the quadratic term of the inlet oxygen concentration c_in_O2 contributes to the decrease of the outlet oxygen concentration c_out_O2.

[0198] Therefore, it should be understood that in order to obtain higher purity nitrogen (to make the outlet oxygen concentration c_out_O2 lower), the ratio of the quadratic term to the introduced oxygen concentration c_in_O2, that is, (quadratic coefficient) / (primary coefficient), is preferably a large positive value, and it is important to set it to at least a value exceeding 0 (zero) at which the contribution of the quadratic term disappears. That is, it is preferable to express the quadratic term with a large positive value.

[0199] Then, in Figure 4 In the figure, the conditions under which (quadratic coefficient) / (primary coefficient) becomes a value exceeding 0 (zero) are determined. It was found that the conditions determined are that when the outlet flow rate f_out is 1.0 L / min, 1.5 L / min, and 2.0 L / min, respectively, the introduction pressure p_in is a value exceeding 2.94 atm (about 0.298 MPa), 3.40 atm (about 0.344 MPa), and 3.86 atm (about 0.391 MPa). It should also be understood that when the outlet flow rate f_out is large, these pressure thresholds are large values. That is, when the outlet flow rate f_out is set to be small, the introduction pressure p_in can be set based on the small pressure threshold.

[0200] In addition, according to the above analysis results, it should be understood that Figure 1 In the nitrogen generating device (system) 1 of the illustrated embodiment, the pressure (introduction pressure) of the exhaust gas applied to the nitrogen filter 12f preferably has a value exceeding a pressure threshold value depending on the nitrogen filter 12f, and the pressure threshold value is a larger value when the flow rate (outlet flow rate) of the exhaust gas extracted from the nitrogen filter 12f is larger.

[0201] [Example 2]

[0202] Figure 5 : is a graph showing Example 2 in which the recovery rate of the nitrogen filter 12f was studied in the nitrogen generation process according to the present invention.

[0203] Here, in Example 2, the same system as in Example 1 was used, and the same conditions as in Example 1 were set for the introduction of oxygen concentration, introduction pressure, and outlet flow rate, and then the recovery rate of the nitrogen filter 12f was measured. However, in Example 2, a measurement was additionally performed in which the introduction of oxygen concentration c_in_O2 was equal to 0 (zero), that is, a measurement in which pure nitrogen was introduced into the filter 12f. In addition, the recovery rate, which was a measurement item of Example 2, was defined as the degree / level of gas recovery in the filter 12f. That is, the recovery rate was calculated according to the following formula.

[0204] (4) (Recovery rate) = (f_out) / (f_in)

[0205] Here, f_in is the flow rate of the introduced gas at the inlet of the filter 12f (introduction flow rate).

[0206] Figure 5 (A), 5(B) and 5(C) are graphs showing the relationship between the introduced oxygen concentration c_in_O2 and the recovery rate under the conditions that the outlet flow rate f_out is 2.0 L / min, 1.5 L / min and 1.0 L / min, respectively.

[0207] According to these figures, it is found that

[0208] (a) When the introduced oxygen concentration c_in_O2 is low (although there may be slight deviations under 4.0 atm (about 0.40 MPa) conditions),

[0209] (b) when the introduction pressure p_in is low (although the difference between 4.0 atm (about 0.40 MPa) and 5.0 atm (about 0.51 MPa) is very small), and

[0210] (c) When the outlet flow rate f_out is large (which is very likely according to the definition of recovery rate), the recovery rate is large.

[0211] For example, under the conditions of (a) to (c) above, even if the exhaust gas having a predetermined flow rate is introduced into the nitrogen filter 12f, a large amount of nitrogen (exhaust gas having a reduced oxygen concentration) is obtained.

[0212] Here, in the above (a) of the introduced oxygen concentration c_in_O2, the direction in which the recovery rate increases and the direction in which the outlet oxygen concentration c_out_O2 decreases (for example, as Figure 2 Specifically, when the introduced oxygen concentration c_in_O2 is low, the outlet oxygen concentration is further reduced and the recovery rate can be higher. Therefore, it is more preferred to use a nitrogen filter with a higher recovery rate when the oxygen concentration of the gas to be filtered is low, so as to produce a larger amount of higher-purity nitrogen.

[0213] And therefore, it should be understood that, considering both the outlet oxygen concentration and the recovery rate, the "fuel cell" that outputs low oxygen concentration exhaust gas and the "nitrogen filter" as described above that uses this exhaust gas are very compatible, and therefore such a system combining them can effectively produce nitrogen.

[0214] On the other hand, in the introduction pressure p_in in the above (b) and the outlet flow rate f_out in the above (c), the direction in which the recovery rate increases (e.g., as Figure 2 The directions in which the recovery rate decreases and the outlet oxygen concentration c_out_O2 decrease are opposite to each other. That is, there is a so-called trade-off relationship between the recovery rate and the outlet oxygen concentration c_out_O2.

[0215] Therefore, for example, when the introduction pressure p_in is larger, high-purity nitrogen with a lower oxygen concentration can be obtained, and on the other hand, the amount of exhaust gas required to obtain a predetermined amount of nitrogen and the required amount of air that ultimately enters the "fuel cell" increases.

[0216] Therefore, in order to achieve the desired low outlet oxygen concentration c_out_O2 and according to the nitrogen generation device (system) 1 ( Figure 1 ) to ensure a predetermined recovery rate, it is preferred to adjust the settings of the introduction pressure p_in and the outlet flow rate f_out. For example, in order to achieve a performance content of producing high-purity nitrogen having a predetermined concentration or greater (e.g., 99.9 vol% or greater) at a predetermined power generation cost (e.g., equal to or less than the power generation cost in the PSA device described below), it is preferred to determine the introduction pressure p_in and the outlet flow rate f_out (and the recovery rate depending on them) while controlling them.

[0217] Regarding the trade-off relationship between the above recovery rate at the introduction pressure p_in and the outlet oxygen concentration c_out_O2 in (b) above, the inventors of the present invention believe that in the nitrogen filter 12f of Example 2 (Example 1) (wherein the filter fiber is a hollow fiber), when the introduction pressure p_in is larger, the hollow fiber expands more, and thus what changes is not only the oxygen molecule selectivity of the filter fiber but also the permeability to molecules other than oxygen molecules.

[0218] Furthermore, regarding the above recovery rate, the inventors of the present invention have confirmed that when the temperature of the gas introduced into the nitrogen filter 12f is high, the recovery rate is low, and at a predetermined temperature or higher, the recovery rate is significantly reduced. Therefore, in the nitrogen generating device (system) 1 ( Figure 1 ), in consideration of ensuring the predetermined recovery rate in the nitrogen filter 12f, the temperature control U 126 ( Figure 1 ) It is preferred to control the temperature of the exhaust gas.

[0219] Here, regarding the effect of the temperature of the introduced gas on the recovery rate, the inventors of the present invention also believe that the hollow fibers of the nitrogen filter 12f expand more at higher temperatures, and thus change not only the oxygen molecule selectivity of the filter fiber but also the permeability to molecules other than oxygen molecules.

[0220] refer to Figures 2 to 5, Examples 1 and 2 have been explained above. Based on the findings from these experiments, the present inventors have successfully used a nitrogen gas generating apparatus (system) 1 to generate high-purity nitrogen gas with a purity (nitrogen concentration) exceeding 99.9 vol% and an oxygen concentration of less than 0.1 vol% (1,000 ppm vol). This high-purity nitrogen gas can be used in reflow soldering equipment with strict purity requirements. In reflow soldering equipment, nitrogen gas with a purity (nitrogen concentration) of 99 vol% can be used, depending on the type of solder paste used.

[0221] Of course, the demand for nitrogen is not limited to the electronic and electrical equipment fields using welding equipment. In fact, nitrogen is used for various applications in a variety of fields and is used in CA (controlled atmosphere) storage atmosphere supply devices or flyer devices. These fields include the metal / resin field where nitrogen is used for laser processing, heat treatment, etc., the transportation equipment field where nitrogen is required, such as tire filling and inside purge equipment, the chemical field where nitrogen is used as various process gases, pressure conveying gas, cooling gas, etc., the mechanical field where nitrogen is required, such as dry cutting equipment, and the food field where nitrogen is used for food preservation and aeration.

[0222] Therefore, the required nitrogen purity (nitrogen concentration) also varies depending on the field and application. For example, there are cases where the oxygen concentration (oxygen concentration) as an impurity gas is required to be approximately 0.01 vol% (100 ppm vol), and there are also cases where an oxygen concentration of up to several vol% may be acceptable.

[0223] In response to this situation, the nitrogen generating apparatus (system) 1 of the present invention adjusts, for example, the introduced oxygen concentration c_in_O2, the introduced pressure p_in, and the outlet flow rate f_out, so that nitrogen can be appropriately supplied while reducing the residual oxygen to the desired upper limit of the oxygen concentration. For example, in a case where the oxygen concentration may be approximately several vol%, the introduced oxygen concentration c_in_O2 can be set to, for example, 10 vol%, while the introduced pressure p_in is kept low and the outlet flow rate f_out is set high, thereby increasing the recovery rate.

[0224] Furthermore, the nitrogen generation device (system) 1 according to the present invention can provide not only the generated nitrogen but also the required electricity and heat depending on its field and application. Of course, in conventional nitrogen generation devices, it is difficult or impossible to cover such energy supply.

[0225] Furthermore, based on the above findings, the inventors of the present invention have confirmed that the nitrogen generation device (system) 1 of the present invention can also significantly reduce the cost of nitrogen generation. For example, according to the investigation of the inventors of the present invention, the current selling price of nitrogen cylinders is, for example, about 430 yen / Nm 3, and the selling price of liquid nitrogen is, for example, about 120 yen / Nm 3 In addition, according to a pressure swing adsorption (PSA) device which is a widely used nitrogen generation device, the nitrogen generation cost is, for example, about 48 yen / Nm 3 .

[0226] On the other hand, preliminary calculations have confirmed that, based on the nitrogen generation device (system) 1, appropriate conditions, including the standard output of the "fuel cell" and the possible exhaust gas flow rate, as well as the expected hydrogen procurement costs, can achieve power generation costs equal to or less than those of the above-mentioned PSA device. Furthermore, as described above, when the nitrogen generation device (system) 1 provides the required electricity and heat, the total procurement cost, including these, can be significantly reduced compared to those of conventional devices.

[0227] [Another embodiment of the dehumidification mechanism: water seal pump U]

[0228] Figure 6 FIG. 1 is a schematic diagram showing another embodiment of the dehumidification mechanism according to the present invention.

[0229] first, Figure 6 (A) shows the water seal pump U 30, which receives the exhaust gas extracted from the air electrode (drainer 112) side of the "fuel cell" of the fuel cell U 11 through the flow control valve, reduces the moisture or water vapor content in the exhaust gas, and sends the exhaust gas that has undergone such dehumidification treatment into the exhaust gas buffer tank 123.

[0230] The water seal pump U 30 includes a water seal pump 301 which is a water seal vacuum pump and a gas-liquid separation tank 302 , and also includes a heat exchanger for cooling the circulating seal liquid (which is a part of the heat exchange U (unit) 40 ).

[0231] Among them, the water seal pump 301 is a vacuum pump, wherein

[0232] (a) Due to the centrifugal force caused by the eccentric rotation of the impeller 301a, the sealing liquid (sealing water) contained in the pump cage forms a crescent-shaped water film inside the pump, and

[0233] (b) Due to the eccentric rotation of the impeller 301a, the volume of the enclosed space formed between the sealing liquid water film and two adjacent blades of the impeller 301a changes periodically, so that the sealing liquid water film acts as a piston and a seal, and specifically, a series of processes are initiated in which the exhaust gas is sucked into the cage, compressed in the cage, and then discharged to the outside of the cage together with the sealing liquid.

[0234] Of course, the structure of the water seal pump 301 is not limited to Figure 6(A) is the structure shown, and any of various structures can be used as this structure as long as it is a structure related to a water seal pump.

[0235] The gas-liquid separator tank 302 is a water storage tank that receives a mixture of exhaust gas and sealing liquid discharged from the water seal pump 301, separates the moisture / water vapor content in the exhaust gas from the sealing liquid, and stores the separated sealing liquid (including the moisture / water vapor content). The stored sealing liquid is returned to the water seal pump 301 via a heat exchanger that is part of the heat exchange unit U40 and reused. When the amount of stored sealing liquid reaches a predetermined amount or more, a portion of it is discharged to the outside of the tank as overflow water.

[0236] In the water seal pump 301, since the impeller 301a is rotated at high speed by the motor, the temperature of the sealing liquid generally rises due to frictional heat, and if it is not cooled, the sealing liquid may boil. Therefore, for example, when the sealing liquid is equal to or higher than a predetermined temperature (e.g., 50°C), the sealing liquid is cooled by the heat exchanger (which is part of the heat exchange U40).

[0237] Heat exchange U 40 regulates (cools) the temperature of the sealing liquid in the water seal pump U 30 in this way, but Figure 6 In the embodiment shown in (A), in addition, another heat exchanger which is part of the heat exchange U 40 is applied to the fuel cell U 11 and regulates (cools) the temperature of the "fuel cell".

[0238] That is, in the heat exchange U 40, the heat exchanger included in the water seal pump U 30 and the heat exchanger incorporated in the fuel cell U 11 are arranged in series, and for example, using a common cooler and pump, it is possible to receive heat from the sealing liquid and the "fuel cell" and adjust (cool) their temperature at the same time. As an alternative, the two heat exchangers can be arranged in parallel to each other to adjust (cool) the temperature at the same time. Of course, the two heat exchangers can also be controlled independently. In addition, the heat exchange U 40 can supply the heat recovered in this way to an external device or facility, or, for example, the recovered heat can be used for cooling and heating in the facility where the device (system) 1 is installed. Here, in this case, the cooler can be omitted.

[0239] Even if the outlet pressure on the air electrode side of the "fuel cell" is "low pressure" close to atmospheric pressure (about 0.1 MPa), for example, the above-mentioned water seal pump 301 can suck the exhaust gas according to the operation of its vacuum pump, dehumidify it, and transfer the resultant to the exhaust buffer tank 123. Here, in such a "low pressure" case, the outlet pressure at the air electrode side of the "fuel cell" drops to less than 1 atm (about 0.1 MPa) according to the suction action of the water seal pump 301, and as a result, the gas after the fuel cell reaction in the cells of the "fuel cell" is expected to be actively extracted, and thus the power generation efficiency of the "fuel cell" is improved.

[0240] In this way, the water seal pump 301 is very suitable for combination with the "fuel cell". In fact, when dehumidifying the exhaust gas of the "fuel cell" where the outlet pressure is 1.2 atm (about 0.12 MPa) and the relative humidity is about 100%, by using the water seal vacuum pump LEH100SMS (commercially available from Kashiyama Industry Co., Ltd.), the exhaust gas having a relative humidity similar to the typical value in the atmosphere (i.e., several tens of%) is obtained, and it can also be quickly stored in the tank 123.

[0241] Incidentally, if the vacuum pump of water seal pump 301 is operated too strongly, excessive gas may be extracted from the fuel cell, potentially hindering the fuel cell reaction. Therefore, it is preferable to adjust the rotational speed of impeller 301a in water seal pump 301 so that the delivery flow rate to exhaust gas buffer tank 123 does not exceed the reference value of the inlet flow rate. Furthermore, to properly perform this adjustment, it is preferable to install a flow meter and a pressure gauge immediately before the suction port and immediately after the extraction port of water seal pump U30 to monitor the flow rate and pressure of the exhaust gas.

[0242] Next, in Figure 6 In the embodiment shown in (B), an adiabatic expansion chamber 50 is provided between the fuel cell U11 and the water seal pump U30. Here, exhaust gas, extracted from the air electrode side of the "fuel cell" via a flow control valve, is drawn into the adiabatic expansion chamber 50 by the suction force of the water seal pump 301. The drawn-in exhaust gas is immediately discharged from the outlet pipe on the air electrode side into the adiabatic expansion chamber 50, which has a predetermined chamber volume. This causes the exhaust gas to adiabatically expand and its temperature to decrease. As a result, a portion of the moisture / water vapor contained in the exhaust gas condenses and accumulates in the lower portion of the adiabatic expansion chamber 50 due to the decrease in saturated water vapor density. Here, when the vacuum pump operation of the water seal pump 301 (the rotation speed of the impeller 301a) is increased within predetermined limits and the flow control valve regulates the flow rate of the exhaust gas flowing into the adiabatic expansion chamber 50 to sharply reduce the exhaust gas pressure, the degree of adiabatic expansion increases, thereby enhancing the dehumidification effect caused by condensation. For example, the temperature of the exhaust gas can be reduced by several tens of degrees Celsius, condensing a large amount of water vapor content and removing it from the exhaust gas.

[0243] In this manner, the adiabatic expansion chamber 50 functions as an exhaust gas dehumidification mechanism preceding the water seal pump U30. In this case, the water seal pump U30 draws in the exhaust gas whose moisture / water vapor content has been reduced after adiabatic expansion, further reducing the moisture / water vapor content in the exhaust gas. Specifically, the installation of the adiabatic expansion chamber 50 allows exhaust gas with an even lower relative humidity to be delivered to the exhaust buffer tank 123.

[0244] Furthermore, in an embodiment of the present invention, a heat exchange U 60 is provided, wherein

[0245] (a) The heat exchanger included in the water seal pump U 30, the heat exchanger installed in the adiabatic expansion chamber 50 (in Figure 6 (B), the tube bundle 501), and the heat exchanger included in the fuel cell U 11 are arranged in series (or in parallel), and

[0246] (b) Receive heat from the sealing liquid of the water seal pump U 30 and the "fuel cell" and transfer the heat to the adiabatic expansion chamber 50, and immediately adjust the temperature of the sealing liquid, the adiabatic expansion chamber 50 and the "fuel cell".

[0247] Heat exchanger U 60 also uses a cooler and a pump to adjust the temperature, but since the heat exchange medium is cooled in the adiabatic expansion chamber 50, a cooler and a pump with low power consumption can be used. Of course, in heat exchanger U 60, the heat recovered in this way can be supplied to an external device or facility, or, for example, the recovered heat can be used for cooling and heating in the facility where the device (system) 1 is installed. Here, in this case as well, the cooler can be omitted.

[0248] As an improved embodiment, in the heat exchanger U 60, the heat exchanger in the "fuel cell" can be omitted, and the heat exchanger U 60 can also be used as a heat transfer mechanism for removing heat from the sealing liquid of the water seal pump U 30 and transferring the heat to the adiabatic expansion chamber 50. In this case as well, the cooler can be omitted or the power consumption can be reduced.

[0249] As yet another embodiment in which the adiabatic expansion chamber 50 is used as a dehumidification mechanism, Figure 6 (B) The configuration omits the water seal pump U 30, and in addition,

[0250] (a) The pressure of the exhaust gas from the "fuel cell" of the fuel cell U 11 is set to a pressure exceeding the atmospheric pressure (1 atm, about 0.1 MPa), for example, a pressure equal to or greater than 3 atm (about 0.3 MPa) (i.e., the "fuel cell" is driven at high pressure using the pressure control U 121 and the pressure control U 113 ( Figure 1 )),and

[0251] (b) Exhausting this high pressure exhaust gas into the adiabatic expansion chamber 50 to release it from the high pressure state and thereby remove a considerable amount of the moisture / water vapor content in the exhaust gas.

[0252] In this case, the exhaust gas can be reliably dehumidified without using the water seal pump U30 requiring a driving force.

[0253] refer to Figure 6 (A) and 6 (B), the dehumidification mechanism using the water seal pump 301 has been described above. In either of the embodiments shown in the two figures, at least a portion of the power for driving the water seal pump U 30 and the cooler and pump can be supplied by a "fuel cell", and in addition, of course, it can be generated by natural energy U 101 ( Figure 1 ) and storage U 101s( Figure 1 ) supply. In addition, it is preferable to provide a pure water recovery mechanism (specifically, such as a pipe, a pump and a filter) to recover the water discharged from the "fuel cell", the water discharged from the adiabatic expansion chamber 50 (in the Figure 6 (B) in the case of the extraction (overflow) water, and also the overflow water of the gas-liquid separation tank 302 (when its purity is high), and the recovered water is provided to the outside as pure water or high-purity water. In this case, the device (system) 1 of the present invention also serves as a pure water supply device (system).

[0254] [An Example of Gas-Liquid Separation U: Dry Filter]

[0255] Figure 7 1 is a schematic diagram showing an embodiment of the gas-liquid separator U 122 as the dehumidification mechanism according to the present invention.

[0256] exist Figure 7 In the embodiment shown, the gas-liquid separator U 122 is a dry filter unit using a dry filter 122f. The dry filter 122f is a filter that can

[0257] (a) receiving exhaust gas having a pressure exceeding atmospheric pressure (1 atm, about 0.1 MPa), for example, 3 atm (about 0.3 MPa) or higher,

[0258] (b) Rapidly change the flow direction of the exhaust gas in the lower part of the container and separate the water, oil and trace mixtures in the exhaust gas,

[0259] (c) the exhaust gas which has been redirected and entered the mesh pipe 122f1 is filtered by the mesh of the mesh pipe 122f1 and the hollow fiber filter therein (which permeates more water vapor than air), and the fine particles / moisture / water vapor content in the exhaust gas is removed, and

[0260] (d) Evaporation of moisture in the exhaust gas by the heat generated during filtration.

[0261] Here, the moisture / water vapor content extracted from the exhaust gas can be discharged to the outside of the filter 122f via the drain 122f2, and this can be supplied to the outside as pure water or high-purity water. Figure 7 The structure shown in FIG. 1 is a schematic diagram of a dry filter structure shown in FIG.

[0262] In such Figure 7 In the embodiment of the present invention shown, in order to supply the exhaust gas having a high pressure (eg, 3 to 7 atm (about 0.3 to 0.7 MPa)) to the dry filter 122f, a mechanism is provided wherein

[0263] (a) using the pressure control U 121 and the pressure control U 113, air (or a gas containing nitrogen and oxygen) having a high pressure (e.g., 3 to 7 atm (about 0.3 to 0.7 MPa)) and hydrogen (fuel gas) having a high pressure (e.g., 3 to 7 atm (about 0.3 to 0.7 MPa)) are supplied to the "fuel cell", and

[0264] (b) Exhaust gas having a high pressure (eg, 3 to 7 atm (about 0.3 to 0.7 MPa)) is extracted from the "fuel cell" and sent to the dry filter 122f.

[0265] As mentioned above, the high-pressure specification "fuel cell" and dry filter 112f are a very suitable combination, that is, the high-pressure system as a series of "fuel cell" and dry filter 112f can effectively remove the generated moisture / water vapor content while improving the battery reaction efficiency.

[0266] Furthermore, in an embodiment of the present invention, the exhaust gas discharged from dry filter 112f (having a reduced moisture or water vapor content and high pressure) is directed to nitrogen filter U12 without passing through (or may pass through) tail gas buffer tank 123. Here, as described above, when the applied exhaust gas pressure is high, the oxygen concentration of the output exhaust gas is lowered in nitrogen filter 12f of nitrogen filter U12, resulting in higher-purity nitrogen. Therefore, it should be understood that dry filter 112f and nitrogen filter U12 are also a highly suitable combination for forming a high-pressure system in their series.

[0267] [Another embodiment of the nitrogen filter U]

[0268] Hereinafter, another preferred embodiment of the nitrogen filter U12 will be described. As described above, Figure 1The nitrogen filter U12 shown includes a filter purge unit that extracts "filter off-gas" containing oxygen molecules separated from nitrogen molecules (in the exhaust gas) by permeating through the hollow fibers of the nitrogen filter 12f. Since the "filter off-gas" discharged from the filter purge unit thus contains a considerable amount of oxygen molecules, it becomes a gas that can be reused in the fuel cell reaction or filtered again.

[0269] Using a UBE N2 separator NM-B01A (commercially available from Ube Industries, Ltd.) as the nitrogen filter 12f, a gas with an oxygen concentration of 10.2 vol% was introduced into the nitrogen filter 12f under conditions of an inlet pressure of 6.0 atm (approximately 0.61 MPa) and an outlet flow rate of 1.0 L / min. The oxygen concentration of the filter off-gas discharged therefrom was then examined. As a result, an oxygen concentration of 14.9 vol% and a recovery rate of 0.29 were achieved. Furthermore, the experiments confirmed that the oxygen concentration in the filter off-gas was higher (a) when the inlet oxygen concentration was higher, (b) when the inlet pressure was lower, and (c) when the outlet flow rate was higher.

[0270] Here, assuming that almost all of the oxygen molecules in the introduced gas are exhausted from the filter purge unit of the nitrogen filter 12f (this is possible because the oxygen concentration at the outlet of the filter 12f is orders of magnitude smaller), using the recovery rate (0.29) obtained in the above experiment, the oxygen concentration of the filter exhaust gas is calculated to be 0.102 / 0.71 = 14.4, which is almost the same as the 14.9 vol% obtained in the above experiment. Therefore, it was found that almost all of the oxygen content that was not separated as an undesirable component could be recovered from the filter purge unit of the nitrogen filter 12f.

[0271] Therefore, the nitrogen generating device (system) 1 of the embodiment of the present invention includes the following Figure 1 The gas return channel indicated by the circled "B" in the figure, and

[0272] (a) Returning the filter exhaust gas to the flow control U 109 installed in the front stage of the air electrode side of the "fuel cell" and reusing it as a gas containing oxygen and nitrogen in the "fuel cell", and / or

[0273] (b) It is sent back to the tail gas buffer tank 123 installed before the nitrogen filter U12, and is applied to the nitrogen filter 12f again together with the exhaust gas.

[0274] Thereby, the oxygen content can be utilized efficiently and nitrogen with a lower oxygen concentration can be extracted.

[0275] Here, if the filter off-gas having a lower oxygen concentration than air is reused in the "fuel cell", the off-gas of the "fuel cell" can become off-gas having a lower oxygen concentration. And thus, since the recovery rate in the nitrogen filter 12f into which such off-gas is introduced becomes large (as shown in FIG. Figure 5 Furthermore, by increasing the final recovery rate in the nitrogen filter 12f in this way, the nitrogen generation cost can also be significantly reduced, although this depends on the settings of various conditions in the nitrogen generation device (system) 1.

[0276] Incidentally, it was found that under the conditions where the oxygen concentration of the exhaust gas from the "fuel cell" is about 15 vol% and the oxygen concentration of the filter exhaust gas is also 1.4 times the introduced oxygen concentration c_in_O2 as a typical value, the oxygen concentration of the filter exhaust gas becomes equal to or higher than the oxygen concentration of the air (20.8 vol%), and as a result, the above advantage of returning the filter exhaust gas to the air electrode side of the "fuel cell" does not occur.

[0277] On the other hand, when the oxygen concentration of the filter off-gas is still 1.4 times the incoming oxygen concentration and the oxygen concentration of the fuel cell exhaust is approximately 10 vol%, the oxygen concentration of the filter off-gas is approximately 14 vol% (<20.8 vol%), and the return of the filter off-gas becomes significant. Furthermore, when the oxygen concentration of the fuel cell exhaust is approximately 5 vol%, the oxygen concentration of the filter off-gas is approximately 7 vol%, which is expected to improve the recovery rate. Depending on the system settings, this can also significantly reduce nitrogen generation costs.

[0278] Hereinafter, still another embodiment of the nitrogen filter U 12 will be described. Figure 8 FIG. 1 is a schematic diagram showing another embodiment of the filtering mechanism according to the present invention.

[0279] according to Figure 8 In the illustrated embodiment, three nitrogen filters 12f1, 12f2, and 12f3 are installed in the nitrogen filter U 12 so that they are connected in parallel. Of course, the number of nitrogen filters connected in parallel is not limited to 3, and may be 2 or 4 or more.

[0280] Specifically, the exhaust gas supplied to the nitrogen filter U12 is divided and drawn into each of the three nitrogen filters 12f1, 12f2, and 12f3. Each nitrogen filter acts on a certain amount of the supply exhaust gas drawn in by itself (each nitrogen filter) and produces a gas with an increased nitrogen concentration, that is, high-purity nitrogen gas, and finally, these high-purity nitrogen gases are combined and sent to the nitrogen tank 129.

[0281] Furthermore, it is preferable to send the filter exhaust gas discharged from each of the three nitrogen filters 12f1, 12f2 and 12f3 back to the flow control U 109 ( Figure 1 ), and / or sent back to nitrogen filter U 12 ( Figure 1 ) of the front stage exhaust gas buffer tank 123 ( Figure 1 ) and reused. Furthermore, when the oxygen concentration in the filter off-gas discharged from these nitrogen filters is equal to or greater than a predetermined value, the filter off-gas can be sent to an external oxygen tank and held and stored. In either case, according to this process, the oxygen content can be more efficiently utilized, and nitrogen with a lower oxygen concentration can be extracted.

[0282] Furthermore, the aforementioned filtration process using multiple nitrogen filters arranged in parallel makes it possible to simultaneously inhale a large amount of exhaust gas and supply an even greater amount of high-purity nitrogen to the outside. For example, according to catalog values for a 4-inch diameter nitrogen filter (commercially available from Daicel-Evonik), when receiving air at 7 atm (approximately 0.7 MPa) at a flow rate of 40 L / min, the 4-inch diameter nitrogen filter discharges high-purity nitrogen with an oxygen concentration of approximately 0.1 vol% at a flow rate of approximately 10 L / min, with a recovery rate of approximately 0.25.

[0283] For example, when three such nitrogen filters are arranged in parallel with each other and exhaust gas (having an oxygen concentration lower than that of air, for example, an oxygen concentration of 5 to 10 vol%) is put into each nitrogen filter at 7 atm (about 0.7 MPa) and at a flow rate of 40 L / min, high-purity nitrogen having an oxygen concentration in the range of 0.01 vol% (100 ppm vol) or an oxygen concentration far below 0.1 vol% (1000 ppm vol) can be supplied to the outside at a total flow rate of about 30 (=10×3) L / min.

[0284] In this case, since the exhaust gas flows into each nitrogen filter at a flow rate of one-third of the original total flow rate of 120 (=40×3) L / min, the oxygen separation capacity of each nitrogen filter is further improved compared to the case of using a single nitrogen filter. Of course, when using a nitrogen filter with a larger diameter (e.g., a 6-inch diameter), a larger amount of high-purity nitrogen can be supplied. For example, in a selective 6-inch diameter nitrogen filter (commercially available from Daicel-Evonik), the recovery rate is approximately 0.32, which is significantly higher than the recovery rate of a 4-inch diameter nitrogen filter (approximately 0.25), and a correspondingly larger amount of high-purity nitrogen can be supplied to the outside.

[0285] Also in the embodiment of the present invention, it is preferred that the overall control U 131 ( Figure 1) continuously monitors the oxygen concentration, pressure and flow rate of the exhaust gas from the "fuel cell" and also the introduced oxygen concentration, introduced pressure, introduced flow rate, introduced gas temperature, outlet oxygen concentration, outlet pressure, outlet flow rate, etc. of each nitrogen filter, and timely controls the individual units so that a predetermined amount (predetermined flow rate) of nitrogen with a predetermined high nitrogen concentration can be provided.

[0286] [Control through machine learning]

[0287] Hereinafter, the control of nitrogen generation in the nitrogen generation device (system) 1 using machine learning will be described, wherein the water seal pump U 30 ( Figure 6 (A)) is used as the dehumidification mechanism according to the present invention, using a nitrogen filter U12 ( Figure 1 ) The exhaust gas that has been dehumidified in the water seal pump U 30 is converted into high-purity nitrogen. Here, the exhaust gas can be converted into high-purity nitrogen in the main control U 131 ( Figure 1 ) to perform this control.

[0288] First, it is assumed that the nitrogen generating device (system) 1 that generates high-purity nitrogen using inhaled air and hydrogen is in a stable operating state. A large number of measurement value data sets obtained in the stable operating state are prepared, for example,

[0289] (a) Regarding the fuel cell U 11 ( Figure 1 ) the air introduction flow rate of the "fuel cell",

[0290] (b) the complex impedance between the hydrogen electrode and the air electrode of the “fuel cell”,

[0291] (c) the temperature of the “fuel cell”,

[0292] (d) the electricity generated by the “fuel cell”,

[0293] (e) The exhaust gas outlet flow rate at the air electrode side of the fuel cell,

[0294] (f) The exhaust gas outlet pressure at the air electrode side of the fuel cell,

[0295] (g) the speed (or driving power) of the impeller 301a in the water seal pump 301,

[0296] (h) The sealing liquid temperature at the water seal pump 301 or the gas-liquid separation tank 302,

[0297] (i) Relative humidity of the exhaust gas at the outlet of the water seal pump U 30,

[0298] (j) the temperature of the exhaust gas introduced into the nitrogen filter U12,

[0299] (k) The pressure of the exhaust gas introduced into the nitrogen filter U12,

[0300] (1) outlet flow rate (of nitrogen) of nitrogen filter U 12, and

[0301] (m) Outlet oxygen concentration (of nitrogen) in the nitrogen filter U12.

[0302] Then, using these data sets, a nitrogen generation model based on, for example, a deep neural network (DNN) algorithm is constructed. Thus, a control program including the constructed model preferably controls the operating state of the nitrogen generation device (system) 1. In the constructed nitrogen generation model, for example, (a) to (k) above can be set as explanatory variables, and (l) and (m) above can be set as target variables.

[0303] By inputting information about the operating states of the fuel cell U 11, the water seal pump U 30, and the nitrogen filter U 12 into the constructed model, the performance of the device (system) 1 can be known or predicted.

[0304] (1') the supply flow rate of high-purity nitrogen gas that can be supplied to the outside, and

[0305] (m') The purity (or oxygen concentration) of the high-purity nitrogen gas that can be supplied to the outside. Here, as explanatory variables for model construction and performance prediction, it is preferred to use at least (a) and (g) above. Furthermore, (l) or (m) above can be set as a target variable.

[0306] As another improved embodiment, a nitrogen generation control model can be constructed in which the above (b) to (f) and the above (h) to (m) are set as explanatory variables, and the above (a) and (g) are set as target variables. The control program including the constructed control model enables the operation state of the nitrogen generation device (system) 1 to be controlled. Thus,

[0307] (a) Regarding the air introduction flow rate of the fuel cell and

[0308] (g) Speed (or driving power) of impeller 301a in water seal pump 301

[0309] These are necessary to achieve the target supply flow rate and target purity (or oxygen concentration) in the high-purity nitrogen to be supplied. Therefore, the target can be achieved by performing control based on these obtained values. Here, it is preferred to use at least one of (1) or (m) above as an explanatory variable for model construction and control amount prediction. Furthermore, (a) or (g) above can be set as a target variable.

[0310] As already mentioned, the nitrogen purity and supply (flow rate) requirements of nitrogen users are very dependent on the field and specific application. In some cases, the overall control U 131 ( Figure 1) It is preferred to construct the nitrogen generation model and the nitrogen generation control model differently according to the requirements of such individual users, and it is preferred to use a control program including the constructed model suitable for the performance desired by the user to make the nitrogen generation device (system) 1 exhibit high performance that meets the user's requirements.

[0311] [Another embodiment using catalyst combustion]

[0312] Figure 9 FIG. 1 is a schematic diagram showing another embodiment of a nitrogen generating device / system according to the present invention.

[0313] exist Figure 9 In the embodiment shown, Figure 1 A catalytic combustion U (unit) 90 is provided after the nitrogen filter U12 in the illustrated nitrogen generation device (system) 1 (for example, immediately after the flow control U 127). The catalytic combustion U90 is a unit that brings hydrogen and oxygen in the exhaust gas into contact with each other over a combustion catalyst composed of a precious metal compound such as palladium (Pd) and platinum (Pt) or other transition metal compounds, and performs catalytic combustion, which is an oxidation reaction that is more controllable than flame combustion.

[0314] Specifically, in an embodiment of the present invention, the catalyst combustion U 90 inhalation

[0315] (a) Nitrogen gas with a low oxygen concentration (for example, an oxygen concentration of 0.1 to several vol%) extracted from the nitrogen filter U12 and

[0316] (b) Hydrogen, which is extracted from the outlet on the hydrogen electrode side of the fuel cell U 11, passes through the drainer 111, the pressure control U 113 and the gas-liquid separation U 114, and is then recovered by the hydrogen recovery U 115, and then sent through the flow control U 902 and the check valve.

[0317] The catalytic combustion unit U 90 then brings these nitrogen and hydrogen gases into contact with each other on the surface of the solid catalyst 90a, which serves as a combustion catalyst installed in the unit, causing a catalytic combustion reaction. Ultimately, high-purity nitrogen with an extremely low oxygen concentration (e.g., an oxygen concentration of approximately 0.01 vol% (100 ppmvol)) and a very small amount of water vapor is supplied to the outside. Of course, instead of the hydrogen in (b) above, hydrogen can be supplied to the catalytic combustion unit U 90 from, for example, the hydrogen generation unit U 102 and / or the fuel reforming and hydrogen generation unit U 103.

[0318] The solid catalyst 90a, which serves as a combustion catalyst installed in the catalyst combustion unit 90, is preferably a ceramic honeycomb having many fine pores and a metal such as platinum (Pt) or palladium (Pd) supported on the surface including the interior of the pores as a catalyst. For example, an NA honeycomb (platinum catalyst, commercially available from Nagamine Manufacturing Co., Ltd.) serving as an oxidation catalyst can be used as the solid catalyst 90a.

[0319] As shown in the catalog, NA honeycomb is a solid catalyst in which platinum group metals such as platinum (Pt) and palladium (Pd) are supported on the surface of a carrier primarily composed of calcium aluminate (CaO·Al2O3), fused silica (SiO2), and titanium dioxide (TiO2). This carrier has a honeycomb shape, and the contact area of the platinum group metal supported on it is large, thereby effectively inducing the oxidation reaction. The optimal operating temperature of the NA honeycomb is 200°C to 850°C.

[0320] In the embodiment of the present invention, since hydrogen is combusted with a small amount of oxygen, the heat of reaction is significantly smaller than in typical catalytic combustion. Therefore, solid catalyst 90a is heated to, for example, 250°C and used as a catalyst for catalytic combustion. For example, electric heating can be used, in which a heating wire is wrapped around solid catalyst 90a and heated by a current.

[0321] In addition, as another preferred embodiment of heating, the solid catalyst 90a can be induction heated. Specifically, iron (Fe) or an iron alloy (such as stainless steel) is mixed into the carrier of the solid catalyst 90a, and an electromagnetic field generating device is used to apply a magnetic field (electromagnetic field) of, for example, tens of kilohertz (kHz) to hundreds of kHz to the solid catalyst 90a. Due to the eddy currents generated according to the principle of electromagnetic induction, the solid catalyst 90a is directly heated by Joule heat.

[0322] Here, based on the skin effect of electromagnetic induction, it is preferable to disperse an iron alloy such as stainless steel in the form of dust, fragments, powder, or flakes near the surface of the solid catalyst carrier 90a, for example, at least in the inner portion of the carrier, at a depth from the surface equal to or greater than the penetration depth δ. Thus, the portion near the surface of the solid catalyst 90a to be heated to a predetermined high temperature with a uniform temperature distribution.

[0323] Alternatively, a plate made of iron or an iron alloy such as stainless steel may be installed so as to contact the side surface of the solid catalyst 90a, for example, and the solid catalyst 90a may be inductively heated by electromagnetic induction via the plate. In any case, in the inductive heating of the solid catalyst 90a, even if a plurality of solid catalysts 90a are used, it is not necessary to wire each solid catalyst 90a, such as by winding a heating wire, and the plurality of solid catalysts 90a may be heated simultaneously and easily.

[0324] As described above, in an embodiment of the present invention, the solid catalyst 90a is heated to promote catalytic combustion. Here, in order to reduce the power required for heating, the oxygen concentration in the nitrogen extracted from the nitrogen filter U12 can be set slightly higher. When the oxygen concentration is large in this way, the heat generated during the catalytic combustion increases, and thus the power used to heat the solid catalyst 90a can be reduced. In any case, considering the purity and supply amount (flow rate) required for the nitrogen to be supplied in the end, it is important to appropriately adjust the filtration conditions of the nitrogen filter U12 (e.g., the introduction flow rate of the exhaust gas) and the combustion conditions of the catalyst (e.g., the temperature of the solid catalyst 90a).

[0325] Furthermore, the nitrogen gas with an extremely low oxygen concentration, which is sent out from the catalyst combustion unit U 90, is sent out at a high temperature. However, the heat can be recovered by a plate-type or multi-tube heat exchanger 901 installed at the outlet of the catalyst combustion unit U 90. In this case, it is preferable to supply the heat recovered by the heat exchanger 901 to the tail gas buffer tank 123 in the same manner as the heat recovered from the fuel cell U 11, and then use it to increase the temperature of the exhaust gas to be supplied to the nitrogen filter U 12 to a high value (e.g., 45°C) or supply it to the outside. Here, when the temperature of the nitrogen gas output from the catalyst combustion unit U 90 is not so high, the gas can be sent to the hydrogen filter U 903, which will be described below, without passing through the heat exchanger 901.

[0326] The nitrogen gas with an extremely low oxygen concentration output from the catalyst combustion U90 generally also includes residual hydrogen that was not burned in the catalyst combustion reaction. In an embodiment of the present invention, the hydrogen filter U903 introduces high-purity nitrogen that has passed through the heat exchange U901, and a known hydrogen filter installed therein separates the residual hydrogen from the nitrogen gas with an extremely low oxygen concentration and outputs high-purity nitrogen. The output high-purity nitrogen is then preferably passed through a check valve, an oxygen concentration meter, a flow meter, and a supercharger U128 ( Figure 1 ) is contained and stored in nitrogen tank 129( Figure 1 ) and appropriately provided to the outside.

[0327] Incidentally, as a hydrogen filter, a filter including, for example, a palladium (Pd)-based hydrogen permeable membrane can be used, or a hydrogen filter including an aromatic polyimide-based gas separation membrane can also be used. For example, UBE GAS SEPARATOR (commercially available from Ube Industries, Ltd.) and SEPURUN Noble (commercially available from Evonik) using a tube in which hollow fiber membranes are bundled can be used.

[0328] Furthermore, in an embodiment of the present invention, hydrogen separated from nitrogen by a hydrogen filter U 903 is sent to a hydrogen recovery U 115 via a flow control U 904, and can then be reused in the fuel cell U 11 or catalytically combusted again in a catalytic combustion U 90. Furthermore, if a reducing atmosphere is required at the nitrogen supply destination, such as an anti-oxidation atmosphere furnace, a flywheel, or the like, the supplied nitrogen can be set to contain a small amount of hydrogen while ensuring safety.

[0329] In addition, as described above, when the nitrogen generating device (system) 1 ( Figure 1 ) When using catalyst combustion U90, the nitrogen filter 12f of the nitrogen filter U 12 can be improved ( Figure 1 That is, considering that the oxygen concentration is ultimately set to a very low value in the catalytic combustion U 90, if the oxygen concentration of the gas output from the nitrogen filter 12f is set to, for example, several vol%, exhaust gas having a considerable flow rate (outlet flow rate) (such as from Figure 2 As a result, the recovery rate in the nitrogen filter 12f can be improved (as can be seen from the figure). Figure 5 can be seen in the figure).

[0330] In addition, Figure 9 In the nitrogen generation device (system) of the illustrated embodiment, nitrogen with a relatively low oxygen concentration can be efficiently generated using only the fuel cell U11 and the catalytic combustion U90 (i.e., without the nitrogen filter U12). In any case, it should be understood that the combination of the "fuel cell" and the "catalytic combustion" is highly suitable for sharing the required hydrogen and efficiently generating nitrogen.

[0331] Incidentally, although this is an embodiment in which a fuel cell is not used, as an apparatus (system) for efficiently generating high-purity nitrogen gas having a sufficiently reduced moisture or water vapor content, a device (system) from Figure 9 The configuration of the device (system) shown omits the device (system) of the fuel cell U 11 , that is, the device includes the nitrogen filter U 12 and the catalyst combustion U 90 as main components.

[0332] [Another embodiment of a fuel cell]

[0333] Figure 10 FIG. 1 is a schematic diagram showing another embodiment of a “fuel cell” according to the present invention.

[0334] Figure 10 shows a suitable as included in the fuel cell U 11 ( Figure 1 ) is a fuel cell 11F of a "fuel cell" in a battery. The fuel cell 11F includes a plurality of cells (these cells are configuration units, each cell including a hydrogen electrode and an air electrode with an electrolyte interposed therebetween), and is designed so that the cells are laminated so that hydrogen (fuel gas) and air (gas containing nitrogen and oxygen) pass through the hydrogen electrode in the cell and the air electrode in the cell, respectively, in this order from the upper cell on the fuel supply side to the lower cell on the opposite side.

[0335] The entire battery is divided into multiple functional battery parts, specifically in Figure 10 In the example, the power generation priority cell section 11Fa, the intermediate cell section 11Fb and the deoxidation cell section 11Fc. Each of the functional cell sections (11Fa, 11Fb and 11Fc) includes one cell or a plurality of consecutive cells ( Figure 10 In the embodiment, two or three batteries, in practice for example several to several hundred batteries) are arranged, and are not electrically connected in series with other functional battery sections, but are electrically connected to a single controller (11Ca, 11Cb, 11Cc) that controls the amount of power generated.

[0336] like Figure 10 As shown, controllers 11Ca, 11Cb, and 11Cc receive the electromotive force generated between the hydrogen electrode and the air electrode in power generation priority cell section 11Fa, intermediate cell section 11Fb, and deoxidation cell section 11Fc, respectively, and output power according to the corresponding functional cell section for which the controller is responsible. Furthermore, in this case, the controller preferably measures the complex impedance of the functional cell section for which the controller is responsible and performs control / management according to the functional cell section.

[0337] On the other hand, conventional fuel cells, particularly PEFC-type conventional fuel cells, are constructed from a series of, for example, several hundred cells electrically connected in series. This is because the electromotive force of a single cell is generally less than 1V (volt). While cells with a low oxygen supply naturally generate less power, it is necessary to achieve a certain degree of uniformity in the power generated by the individual cells connected in series. Consequently, the power generation efficiency (relative to the hydrogen supply) of all the series-connected cells, including these cells with a low oxygen supply, is significantly affected.

[0338] In contrast, in the fuel cell 11F,

[0339] (a) a power generation priority cell portion 11Fa having a large oxygen supply amount (in which oxygen in the supply air is not consumed much),

[0340] (b) an intermediate cell portion 11Fb, which is an intermediate body with respect to oxygen supply amount, and

[0341] (c) Deoxygenation cell section 11Fc with a small oxygen supply (consumes a large amount of oxygen in the supply air)

[0342] The power generation amount control suitable for each oxygen supply amount can be individually received. Therefore, by implementing such power generation amount control, both the oxygen reduction efficiency and the power generation efficiency (with respect to the hydrogen supply amount) can be maximized or improved in the fuel cell 11F.

[0343] In this way, the fuel cell 11F acts as the fuel cell U 11 ( Figure 1 ) is a very suitable fuel cell for generating high-purity nitrogen. Of course, the fuel cell 11F can also be used for other general objects as a suitable fuel cell capable of optimizing power generation efficiency.

[0344] Incidentally, the number of functional cell sections in the fuel cell 11F is not limited to three and may be two or four or more. For example, among hundreds of cells, the lower 150-level cell group and the remaining upper cell group may serve as the first functional cell section and the second functional cell section, respectively.

[0345] As described above, according to the present invention, high-purity nitrogen can be reliably and stably generated using a fuel cell. In particular, by dehumidifying the exhaust gas from the fuel cell using a water seal pump or a dry filter, and also using a nitrogen filter and catalytic combustion, higher-purity nitrogen can be generated more reliably, stably, and efficiently.

[0346] Furthermore, in the future, when a hydrogen / zero-carbon society emerges, the use of fuel cells using hydrogen as fuel gas is expected to become widespread. This invention will significantly facilitate efficient nitrogen production in such an era. Of course, it will also enable on-site supply of electricity and heat, and in some cases, pure water. In other words, it is believed that this invention will significantly facilitate the development of a zero-carbon energy / product demand-supply system for local production and local consumption, which is considered an ideal future scenario.

[0347] Furthermore, according to the present invention, although this is only one embodiment of the present invention, it is also possible to utilize a hydrogen generator including an electrolysis unit to supply hydrogen as fuel gas to a fuel cell. This configuration is also expected to be of great use in the aforementioned hydrogen society / zero-carbon society.

[0348] Many widely different alternatives and modifications of the various embodiments of the present invention may be constructed without departing from the spirit and scope of the present invention. All of the foregoing embodiments are merely examples of the present invention and are not intended to be limiting. Therefore, the present invention is limited only as defined in the following claims and their equivalents.

[0349] Reference Signs List

[0350] 1 Nitrogen generation device / system

[0351] 101 Natural Energy Power Generation U (unit)

[0352] 101s Battery U

[0353] 102 Hydrogen Production U

[0354] 103 Fuel Reforming and Hydrogen Generation

[0355] 104 Hydrogen Tanks

[0356] 105, 109, 127, 902, 904 Flow Control

[0357] 106 Air Compressor

[0358] 107 Air Tank

[0359] 108 Filter U

[0360] 11 Fuel Cell U

[0361] 11Ca, 11Cb, 11Cc controllers

[0362] 11F Fuel Cell

[0363] 11Fa power generation priority battery part

[0364] 11Fb middle battery part

[0365] 11Fc deoxygenation cell part

[0366] 111, 112 drains

[0367] 113, 121 Pressure Control U

[0368] 114, 122 Gas-Liquid Separation

[0369] 115 Hydrogen Recovery

[0370] 12 Nitrogen filter U

[0371] 12f, 12f1, 12f2, 12f3 nitrogen filters

[0372] 122f dry filter

[0373] 112f1 Network Management

[0374] 122f2 Drain

[0375] 123 exhaust buffer tank

[0376] 124, 128 Supercharger U

[0377] 125 Corrosive gas removal

[0378] 126 Temperature Control

[0379] 129 Nitrogen Tank

[0380] 131 Total Control U

[0381] 30 Water seal pump U

[0382] 301 water seal pump

[0383] 302 gas-liquid separation tank

[0384] 40, 60, 901 heat exchange U

[0385] 50 Adiabatic expansion chamber

[0386] 501 Discipline

[0387] 90 Catalytic Combustion U

[0388] 90a solid catalyst

[0389] 903 Hydrogen Filter U

Claims

1. A nitrogen generating device comprising: a fuel cell configured to operate by taking in air or a gas containing nitrogen and oxygen and a fuel gas, and to discharge an exhaust gas having an oxygen concentration lower than that of air from an outlet on one side of an air electrode; a filtering mechanism including a filter using fibers having different permeabilities to nitrogen and oxygen and configured to further reduce the oxygen concentration in the exhaust gas by applying the exhaust gas to the filter, thereby converting the exhaust gas into a gas having an increased nitrogen concentration; and It further includes a catalyst combustion mechanism, which is configured to cause the gas with increased nitrogen concentration extracted from the filter to react with the fuel gas on a combustion catalyst, further reduce the oxygen concentration of the gas with increased nitrogen concentration, and convert the gas with increased nitrogen concentration into a gas with further increased nitrogen concentration.

2. The nitrogen generating device according to claim 1, further comprising a supercharger mechanism configured to increase the pressure of the exhaust gas. Wherein the filtering mechanism is adapted to convert the exhaust gas having an increased pressure into a gas having an increased nitrogen concentration.

3. The nitrogen generating device according to claim 1, wherein: This filter is a filter in which the recovery rate is higher when the oxygen concentration of the gas to be filtered is lower.

4. The nitrogen generating device according to claim 1 , further comprising a gas reflux passage in which filter off-gas is extracted from the filter to which the off-gas is applied, the filter off-gas being a gas containing gas that has permeated the fibers and being different from the gas having an increased nitrogen concentration, and the extracted filter off-gas is added to the air or the gas containing nitrogen and oxygen to be supplied to the fuel cell and used in the fuel cell, and / or is added to the off-gas to be supplied to the filtering mechanism and used in the filtering mechanism.

5. The nitrogen generating device according to claim 1, wherein: The filtering mechanism includes a plurality of filters arranged in parallel with each other, and each of the filters acts on a certain amount of supply exhaust gas drawn into each of the filters.

6. The nitrogen generating device according to claim 1, wherein: The catalyst combustion mechanism reacts the gas having an increased nitrogen concentration with the fuel gas on the combustion catalyst heated by electromagnetic induction.

7. The nitrogen generating apparatus according to claim 1 , further comprising a pressure controller configured to enable supply of air having a pressure exceeding atmospheric pressure or a gas containing nitrogen and oxygen and having a pressure exceeding atmospheric pressure, and a fuel gas having a pressure exceeding atmospheric pressure to the fuel cell. The filtering mechanism converts the exhaust gas having a pressure exceeding atmospheric pressure into a gas having an increased nitrogen concentration.

8. The nitrogen generating device according to claim 7, further comprising a dry filter unit that reduces the moisture or water vapor content in the exhaust gas having a pressure exceeding atmospheric pressure, and in, The filtering mechanism converts exhaust gas having a reduced moisture or water vapor content and having a pressure exceeding atmospheric pressure into a gas having an increased nitrogen concentration.

9. The nitrogen generating device according to claim 1, wherein: The fuel cell includes a plurality of cells arranged as a unit, each cell including two electrodes with an electrolyte disposed therebetween, all of the plurality of cells being divided into a plurality of functional cell sections, each functional cell section including one cell or a plurality of consecutive cells and not electrically connected in series to other functional cell sections but being electrically connected to a single controller that controls the amount of power generated.

10. A nitrogen generation system comprising: a fuel cell configured to operate by taking in air or a gas containing nitrogen and oxygen and a fuel gas, and to discharge an exhaust gas having an oxygen concentration lower than that of air from an outlet on one side of an air electrode; a filtering mechanism including a filter using fibers having different permeabilities to nitrogen and oxygen and configured to further reduce the oxygen concentration in the exhaust gas by applying the exhaust gas to the filter, thereby converting the exhaust gas into a gas having an increased nitrogen concentration; and It further includes a catalyst combustion mechanism, which is configured to cause the gas with increased nitrogen concentration extracted from the filter to react with the fuel gas on a combustion catalyst, further reduce the oxygen concentration of the gas with increased nitrogen concentration, and convert the gas with increased nitrogen concentration into a gas with further increased nitrogen concentration.

11. A method for generating nitrogen, comprising: supplying air or a gas containing nitrogen and oxygen and a fuel gas to a fuel cell and operating the fuel cell; extracting an exhaust gas having an oxygen concentration lower than that of air from an outlet on the air electrode side of the fuel cell; applying the exhaust gas to a filter using fibers having different permeabilities to nitrogen and oxygen and further reducing the oxygen concentration in the exhaust gas, and extracting a gas having an increased nitrogen concentration from the filter; and The step of allowing the gas with increased nitrogen concentration extracted from the filter to react with the fuel gas on a combustion catalyst to further reduce the oxygen concentration of the gas with increased nitrogen concentration and convert the gas with increased nitrogen concentration into a gas with further increased nitrogen concentration.

Images