Nitrogen gas generation device and method for dehumidifying fuel cell exhaust gas by water exchange

Abstract

To provide a device that reliably and stably generates high-purity nitrogen gas using a fuel cell.SOLUTION: A nitrogen gas generation device includes a fuel cell that operates by taking in gas including air or nitrogen and oxygen and fuel gas, water exchange dehumidification means that performs water exchange between exhaust gas having lower oxygen concentration than the air taken out of the fuel cell and the gas including air or nitrogen and oxygen introduced into the fuel cell, and reduces moisture or water vapor content in exhaust gas, and nitrogen filtering means that includes filters with different degrees of permeation for nitrogen and oxygen, and converts exhaust gas with reduced moisture or water vapor content into gas with increased nitrogen concentration, and preferably further includes high-pressure gas supply means capable of supplying, to the fuel cell, high-pressure air having pressure greater than or equal to a pressure threshold set on the basis of minimum pressure required or determined at least in the nitrogen filtering means and high-pressure gas containing nitrogen and oxygen.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a technique for generating high-purity nitrogen gas.

Background Art

[0002] In recent years, the use of fuel cells has been actively promoted. For example, fuel cell vehicles have been commercialized, and household and industrial fuel cell equipment are also becoming more widespread. Using fuel cells not only enables highly efficient power generation, but also, unlike conventional power generation means using internal combustion engines, makes it possible to substantially reduce carbon dioxide emissions to almost zero. Therefore, fuel cell technology is expected to significantly contribute to the realization of carbon neutrality, a pressing issue, even considering a carbon-zero society.

[0003] The inventors of the present application have focused on the potential of such fuel cells and, as described in Patent Documents 1 to 8, have invented various devices and systems using fuel cells. In particular, as disclosed in Patent Documents 6 and 7, a nitrogen gas generation device has been invented that acts exhaust gas taken out from a fuel cell on a nitrogen filter and extracts gas with an increased nitrogen concentration from this filter. Also, as disclosed in Patent Document 8, a configuration has been invented in which the important dehumidification treatment of the exhaust gas in this nitrogen gas generation device is carried out using a water seal pump.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0005] Thus, the inventors of the present invention realized that by utilizing fuel cells, it would be possible to supply high-purity nitrogen gas, which is in high demand at various production and service provision sites.

[0006] Such high-purity nitrogen gas is an inert gas that neither supports nor assists combustion, making it extremely useful. However, currently, it is produced using air as a raw material through methods such as pressure fluctuation adsorption (PSA), cryogenic air separation, and membrane separation. The inventors of this invention hypothesized that, instead of using air directly as a raw material, it might be possible to produce high-purity nitrogen gas efficiently and at low cost by utilizing the exhaust gas from fuel cells.

[0007] One important challenge here is how to reduce the oxygen concentration in the exhaust gas. Another important challenge is how to dehumidify the exhaust gas extracted from the fuel cell, which has a relative humidity of approximately 100%. In this regard, if the exhaust gas is not properly dehumidified, it will hinder the subsequent oxygen concentration reduction process, making it difficult to carry out the process reliably and stably. Of course, the nitrogen gas generators disclosed in, for example, Patent Documents 6 to 8 are important solutions to these problems, but the inventors of this application have been seeking an even more suitable device configuration because they employ a fuel cell.

[0008] Therefore, the present invention aims to provide an apparatus, system, and method for reliably and stably generating high-purity nitrogen gas using a fuel cell. [Means for solving the problem]

[0009] According to the present invention, A fuel cell that operates by taking in air, or a gas containing nitrogen and oxygen, and a fuel gas, A water exchange dehumidification means that performs water exchange between exhaust gas having a lower oxygen concentration than air, extracted from a fuel cell, and the air or gas containing nitrogen and oxygen that is taken into the fuel cell, thereby reducing the moisture or water vapor content in the exhaust gas, It is equipped with filters with different degrees of permeability for nitrogen and oxygen, and is a nitrogen filtering means that converts the exhaust gas, which has had its moisture or water vapor content reduced, into a gas with an increased nitrogen concentration. A nitrogen gas generator having the following is provided.

[0010] As one embodiment of the nitrogen gas generator according to the present invention, the nitrogen gas generator further comprises a high-pressure gas supply means capable of supplying high-pressure air or a gas containing high-pressure nitrogen and oxygen having a pressure equal to or greater than a pressure threshold set based on the lower pressure limit pressure required or determined by the nitrogen filtering means to a fuel cell. The water exchange dehumidification means reduces the moisture or water vapor content in the high-pressure exhaust gas having a pressure above the pressure threshold. The nitrogen filtering means may also be used to reduce the moisture or water vapor content of the high-pressure exhaust gas, thereby increasing the nitrogen concentration of the gas.

[0011] Furthermore, in the embodiment relating to the high-pressure gas supply described above, the nitrogen gas generator further comprises a dry filtering means equipped with a dry filter for further reducing the moisture or water vapor content in the high-pressure exhaust gas extracted from the water exchange dehumidification means, and it is preferable that the pressure threshold is set based on a lower limit pressure required or determined by the dry filtering means. Moreover, it is preferable that the lower limit pressure be set to a pressure value of at least 3 atmospheres or higher.

[0012] Furthermore, in the embodiment relating to the high-pressure gas supply described above, it is also preferable that the nitrogen gas generator further includes a catalytic combustion means that reacts the high-pressure exhaust gas, which has a reduced moisture or water vapor content before being taken into the nitrogen filtering means, with the fuel gas on a combustion catalyst, or reacts the gas with an increased nitrogen concentration, which has been taken out of the nitrogen filtering means, with the fuel gas on a combustion catalyst to further reduce the oxygen concentration in the high-pressure exhaust gas or the gas with an increased nitrogen concentration.

[0013] Furthermore, in the embodiment relating to the high-pressure gas supply described above, the nitrogen gas generator further comprises a high-pressure electrolysis means that electrolyzes a decomposition target, which is water or water vapor supplied in a limited space, or a decomposition target containing water or water vapor, to generate high-pressure hydrogen gas having a pressure above a pressure threshold, and the fuel cell also preferably takes in the high-pressure hydrogen gas and the high-pressure air or a gas containing the high-pressure nitrogen and oxygen, and discharges the high-pressure exhaust gas. It is also preferable that the high-pressure electrolysis means further comprises a heat transfer means that transfers heat from the fuel cell to the high-pressure electrolysis means and uses at least the heat to generate the high-pressure hydrogen gas.

[0014] Furthermore, in an embodiment equipped with the above-described high-pressure electrolysis means, the nitrogen gas generating apparatus is A dry filtering means equipped with a dry filter for further reducing the moisture or water vapor content in the high-pressure exhaust gas extracted from the water exchange dehumidification means, A water supply means that supplies water from a dry filtering means, or water from a dry filtering means and a fuel cell, to a high-pressure electrolysis means as the object to be decomposed. It is also preferable to have further.

[0015] Also, in the embodiment provided with the above high-pressure electrolysis means, the nitrogen gas generation device reacts the high-pressure exhaust gas with reduced moisture or water vapor content before being incorporated into the nitrogen filtering means and the fuel gas on a combustion catalyst, or reacts the gas with increased nitrogen concentration taken out from the nitrogen filtering means and the fuel gas on a combustion catalyst to further reduce the oxygen concentration in the high-pressure exhaust gas or the gas with increased nitrogen concentration. It is also preferable that the catalytic combustion means uses at least the generated high-pressure hydrogen gas as the fuel gas used for catalytic combustion.

[0016] Furthermore, in the embodiment provided with the above high-pressure electrolysis means, the high-pressure gas supply means comprises gas pressure driving means that generates driving force using the generated high-pressure hydrogen gas and / or high-pressure oxygen gas having a pressure equal to or higher than the pressure threshold generated by the high-pressure electrolysis means, and gas pressure compression means that makes the air or the gas containing nitrogen and oxygen into the high-pressure air or the gas containing high-pressure nitrogen and oxygen by the received driving force. It is also preferable that it is provided with this.

[0017] Also, in the embodiment provided with catalytic combustion means among the above-described embodiments, it is also preferable that the nitrogen gas generation device further comprises heat transfer means that transfers heat from a fuel cell to the catalytic combustion means and uses at least the heat to heat the combustion catalyst required during catalytic combustion.

[0018] Furthermore, as another embodiment of the nitrogen gas generation device according to the present invention, the nitrogen gas generation device comprises pressure adjustment means that makes the exhaust gas taken out from the water exchange dehumidification means into high-pressure exhaust gas having a pressure equal to or higher than a pressure threshold set based on at least the lower limit pressure required or determined in the nitrogen filtering means. A dry filtering means equipped with a dry filter further reduces the moisture or water vapor content in the high-pressure exhaust gas taken out from the pressure regulating means. It is also preferable to have the following features. Furthermore, it is preferable that the lower limit pressure be set to a pressure value of at least 3 atmospheres or more.

[0019] Furthermore, in another embodiment of the nitrogen gas generator according to the present invention, it is preferable that the nitrogen gas generator further includes a temperature adjustment means for adjusting the temperature of the exhaust gas extracted from the fuel cell, and / or the temperature of the exhaust gas before it is taken into the nitrogen filtering means, to a temperature above a temperature threshold set based on the lower limit temperature required or determined in the water exchange dehumidification means and / or nitrogen filtering means. It is also preferable that this temperature adjustment means uses heat from the fuel cell to control the temperature of the exhaust gas to a temperature above the temperature threshold.

[0020] Furthermore, in another embodiment of the nitrogen gas generating device according to the present invention, the fuel cell comprises a plurality of cells, which are constituent units including two electrodes with an electrolyte in between, and the entire plurality of such cells is divided into a plurality of functional cell sections, each functional cell section comprising one or a plurality of consecutive cells, which are not electrically connected in series with other functional cell sections, but are electrically connected to individual power generation control units.

[0021] According to the present invention, A fuel cell that operates by taking in air, or a gas containing nitrogen and oxygen, and a fuel gas, A water exchange dehumidification means that performs water exchange between exhaust gas having a lower oxygen concentration than air, extracted from a fuel cell, and the air or gas containing nitrogen and oxygen that is taken into the fuel cell, thereby reducing the moisture or water vapor content in the exhaust gas, It is equipped with filters with different degrees of permeability for nitrogen and oxygen, and is a nitrogen filtering means that converts the exhaust gas, which has had its moisture or water vapor content reduced, into a gas with an increased nitrogen concentration. A nitrogen gas generation system having the following characteristics is provided.

[0022] According to the present invention, The steps include supplying air, or a gas containing nitrogen and oxygen, and a fuel gas to a fuel cell to operate the fuel cell, A step of performing a water exchange between exhaust gas, which has a lower oxygen concentration than air and is extracted from a fuel cell, and the air or gas containing nitrogen and oxygen that is taken into the fuel cell, thereby reducing the moisture or water vapor content in the exhaust gas. The exhaust gas, with reduced moisture or water vapor content, is subjected to filters with different degrees of permeability for nitrogen and oxygen, and the exhaust gas with increased nitrogen concentration is extracted from these filters. A method for generating nitrogen gas having the following characteristics is provided. [Effects of the Invention]

[0023] According to the present invention, high-purity nitrogen gas can be reliably and stably produced using a fuel cell. [Brief explanation of the drawing]

[0024] [Figure 1] This is a schematic diagram showing one embodiment of the nitrogen gas generating apparatus / system according to the present invention. [Figure 2] This is a schematic diagram showing one embodiment of a combination of the water exchange dehumidification means and fuel cell according to the present invention. [Figure 3] This is a schematic diagram showing another embodiment of the filtering means according to the present invention. [Figure 4] This is a schematic diagram showing another embodiment of the nitrogen gas generating apparatus / system according to the present invention. [Figure 5] This is a schematic diagram illustrating yet another embodiment of the nitrogen gas generating apparatus / system according to the present invention. [Figure 6] This is a schematic diagram showing another embodiment of the high-pressure gas supply means according to the present invention. [Figure 7] This is a schematic diagram illustrating another embodiment of the fuel cell unit according to the present invention. [Modes for carrying out the invention]

[0025] The embodiments for carrying out the present invention will be described in detail below with reference to the accompanying drawings. In each drawing, identical components are indicated by the same reference numeral. Components that can have similar structure and function may also be indicated by the same reference numeral. Furthermore, the dimensional ratios within and between components in the drawings are arbitrary for the sake of readability.

[0026] [Nitrogen gas generator / system] Figure 1 is a schematic diagram showing one embodiment of the nitrogen gas generating apparatus / system according to the present invention.

[0027] The nitrogen gas generator 1 (or nitrogen gas generation system 1) shown in Figure 1 as an embodiment of the present invention is, (A) A fuel cell 104 that operates by taking in "air, or a gas containing nitrogen and oxygen" and "fuel gas" (hydrogen gas in this embodiment), (B) A water exchange dehumidification unit (U) 105 performs water exchange between the "exhaust gas" (off-gas) extracted from the fuel cell 104, which has a lower oxygen concentration than air, and the "air, or a gas containing nitrogen and oxygen" taken into the fuel cell 104, thereby reducing the moisture or water vapor content in the "exhaust gas". (C) Equipped with filters with different degrees of permeability for nitrogen and oxygen, the nitrogen filter U109 converts the exhaust gas with reduced moisture or water vapor content into a gas with increased nitrogen concentration. It is characterized by having [this feature].

[0028] Of these, the nitrogen filter U109 described in (C) above is a means of further removing (filtering) oxygen (O2) gas from the "exhaust gas," which has a lower oxygen concentration than air, and outputting gas with an increased nitrogen concentration (high-purity nitrogen gas in this embodiment). Here, immediately after being discharged from the fuel cell 104, the "exhaust gas" is usually a gas with a relative humidity of approximately 100%. Therefore, dehumidification of the "exhaust gas" is extremely important in order to continuously perform good nitrogen filtering in the nitrogen filter U109.

[0029] In contrast, the water exchange dehumidification U105 described in (B) above is a dehumidification means that moves water vapor (H2O) from the "exhaust gas" to "air, or a gas containing nitrogen and oxygen" (performing water exchange) via a water vapor exchange membrane, for example, to make the "exhaust gas" a gas with reduced moisture or water vapor content. The "exhaust gas" becomes a gas that can be subjected to good nitrogen filtering treatment in the nitrogen filtering U109 by this water exchange dehumidification U105.

[0030] In this case, the "air, or gas containing nitrogen and oxygen" taken into the fuel cell 104 is actually humidified by this water exchange dehumidification U105. As a result, especially when the fuel cell 104 is a polymer electrolyte fuel cell (PEFC), the polymer membrane (electrolyte layer), which is essential for the fuel cell reaction, can maintain a moist state and thus maintain high proton conductivity. Consequently, a good fuel cell reaction becomes possible, and in turn, exhaust gas with sufficient oxygen consumption can be provided.

[0031] Thus, the water exchange dehumidifier U105 not only prepares the output gas from the fuel cell 104 into a gas suitable for nitrogen filtering, but (depending on the type and method of the fuel cell 104) it can also adjust the gas introduced into the fuel cell 104 into a gas suitable for the fuel cell reaction. In other words, by combining this water exchange dehumidifier U105 with the fuel cell 104 and the nitrogen filter U109 in an intermediary manner, high-purity nitrogen gas can be reliably and stably produced.

[0032] Incidentally, particularly in the field of fuel cell vehicles, humidifiers that humidify the air taken into the fuel cell with water vapor from exhaust gases are well known. For example, Patent Publication No. 2006-156203 discloses a humidifier that performs water exchange between the off-gas and the supply gas via a permeable membrane (water vapor exchange membrane). However, this known humidifier is merely a means of humidifying the air taken into the fuel cell, and in reality, the exhaust gas from the humidifier is simply discharged and has not been utilized in any way.

[0033] Furthermore, the terms "high purity" or "highly pure" used above refer to a state in which the oxygen concentration in the nitrogen gas has been sufficiently reduced. Specifically, the nitrogen concentration (in ml per 100 ml of medium, in units of vol%) in the "high purity" or "highly pure" nitrogen gas produced in this embodiment may be set to, for example, 95 vol% or higher, 99 vol% (2N) or higher, or even 99.9 vol% (3N) or higher, depending on the field and application of use of the nitrogen gas.

[0034] Furthermore, the pressure (gas pressure) values ​​for air, hydrogen gas, etc., listed below are absolute pressure values ​​based on a vacuum, meaning atmospheric pressure is set at 1 atmosphere (approximately 0.1 M Pascals (Pa)). For example, the "9 atmospheres" shown below corresponds to 8 atmospheres when measured by a pressure gauge installed in air or exhaust gas piping, which is based on atmospheric pressure.

[0035] [Device / System Configuration] As also shown in Figure 1, the nitrogen gas generator (system) 1 of this embodiment is (a) High-pressure gas supply unit (U) 101, (b) Fuel cell U103 equipped with fuel cell 104, (c) Water exchange dehumidifier U105 and (d) Dry filtering U107 equipped with dry filter 107F, (e) Nitrogen filtering U109 equipped with nitrogen gas filter 109F, (f) Gas reforming U121 and, (g) Pressure booster U123 and, (h) Hydrogen recovery U129 and, (i) Overall control U131 and The device (system) is equipped with the ability to take in "air, or a gas containing nitrogen and oxygen," generate high-purity nitrogen gas, and supply it to the outside. In the following explanation, air is used as the intake, but of course, "a gas containing nitrogen and oxygen" may also be used.

[0036] Furthermore, the nitrogen gas generation system 1 may, for example, include a device equipped with a fuel cell U103 and a water exchange dehumidifier U105, and a dry filter U107 and a nitrogen filter U109 located outside this device. Here, the dry filter U107 may be a unit within this device, and may be omitted as described later. Moreover, the nitrogen gas generation system 1 may not include a gas reformer U121 and may obtain hydrogen gas from outside the system.

[0037] Furthermore, the nitrogen gas generation system 1 can also be configured as a system that connects the "fuel cell-mounted dehumidifying filtering device (system)," which includes a piping joint connectable to the air intake and exhaust gas outlet of the fuel cell 104, a water exchange dehumidifier U105, a dry filter U107, and a nitrogen filter U109, to the "fuel cell U103."

[0038] Incidentally, the flow of mass and energy transfer and the processes performed, as shown by connecting the components with arrows in the apparatus / system configuration diagram of Figure 1, can also be understood as one embodiment of the nitrogen gas generation method according to the present invention.

[0039] <Means of supplying high-pressure gas> Also in Figure 1, the high-pressure gas supply U101 in this embodiment is a unit comprising a compressor that compresses air taken in from the atmosphere and supplies the generated high-pressure air to the fuel cell U103 (water exchange dehumidification U105), and an electric motor for operating this compressor. Here, various types of compressors can be used, such as reciprocating type, scroll type, screw type, rotary type, or swing type, or a combination of two or more of these.

[0040] Furthermore, in this embodiment, the high-pressure gas supply U101 is configured to supply high-pressure air having a pressure equal to or greater than a "pressure threshold" set (taking into account pressure loss within the device (system) 1) based on the "lower limit pressure" required or determined in at least the nitrogen filtering U109, preferably the dry filtering U107 and nitrogen filtering U109, to the fuel cell U103 (water exchange dehumidification U105). Here, the "lower limit pressure" is, as will also be explained later, a pressure value that is significantly higher than atmospheric pressure (1 atmosphere, approximately 0.1 megapascals (MPa)), and is set to a high pressure value of at least 3 atmospheres (approximately 0.3 MPa) or more.

[0041] Furthermore, the high-pressure gas supply U101 may have a buffer tank, in which compressed air may be temporarily stored at high pressure. Alternatively, the high-pressure air taken from this buffer tank may be passed through an air filter and oil filter that the unit itself has installed, thereby supplying high-pressure air from which fine dust and oil components have been removed.

[0042] Furthermore, other preferred embodiments of the high-pressure gas supply U101, specifically embodiments using a gas pressure motor and a compression pump, will be described in detail later with reference to Figure 6. Incidentally, if, for example, a compressed air supply facility is available at the site where the nitrogen gas generation device (system) 1 is to be introduced, this high-pressure gas supply U101 can be omitted.

[0043] Also in Figure 1, the flow controller FCa is a device that controls the flow rate and pressure of the high-pressure air supplied from the high-pressure gas supply U101 to the water exchange dehumidifier U105. Specifically, it can be a gas regulator and a mass flow controller (or flow switch). In this embodiment, this high-pressure air is supplied to the water exchange dehumidifier U105 while maintaining a high pressure, for example, 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa).

[0044] <Water exchange dehumidification means> In this embodiment, the water exchange dehumidifier U105 is, (a) The received high-pressure air having a pressure greater than or equal to the above-mentioned "pressure threshold," for example, a high pressure of 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa) in this embodiment, (b) Exhaust gas extracted from the fuel cell 104 having an oxygen concentration lower than that of air This provides a means of reducing the moisture or water vapor content in the exhaust gas described in (b) above by performing water exchange between the two. Furthermore, this also makes it possible to humidify the high-pressure air described in (a) above and supply moist high-pressure air to the fuel cell 104, thereby enabling a favorable fuel cell reaction to be carried out continuously (for example, by keeping the electrolyte layer moist).

[0045] The configuration and functions of this water-exchange dehumidifier U105 will be explained in detail later using Figure 2.

[0046] <Means of hydrogen production> Also in Figure 1, gas reformer U121 takes in a hydrocarbon gas such as city gas or LP (Liquefied Petroleum) gas, mixes this hydrocarbon gas with water vapor, and produces a hydrogen-containing gas mainly composed of hydrogen (H2) from this mixed gas through a water vapor reforming reaction. It is also preferable to have a mechanism to reduce the carbon monoxide gas content in the generated hydrogen-containing gas using a CO-modified catalyst, or to further reduce the carbon monoxide concentration using a CO-selective oxidation catalyst.

[0047] Furthermore, in this embodiment, the pressure booster U123 is equipped with a hydrogen storage alloy cylinder that temporarily stores the hydrogen gas supplied from the gas reformer U121 in a compressed (high-pressure) state, and serves as a unit that supplies high-pressure hydrogen gas to the fuel cell 104.

[0048] Furthermore, the flow controller FCb is a device that controls the flow rate and pressure of hydrogen gas supplied from the pressure booster U123 to the fuel cell 104. Specifically, it can be equipped with a hydrogen gas regulator and a hydrogen gas mass flow controller (or flow switch). In this embodiment, this high-pressure hydrogen gas is supplied to the fuel cell 104 at a pressure equivalent to that of the high-pressure air, for example, 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa). This makes it possible to apply equivalent pressure to each layer surface in the electrolyte layer of the fuel cell 104, for example, and prevent damage to the electrolyte layer.

[0049] Also in Figure 1, the pressure controller PCc, located downstream of the exhaust gas outlet on the hydrogen electrode side (fuel gas chamber side) of the fuel cell U103, is a device for maintaining the back pressure on the hydrogen electrode side (fuel gas chamber side) of the fuel cell 104 at a predetermined set pressure, for example, 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa) in this embodiment. In other words, it plays the role of maintaining the exhaust gas, i.e., the back pressure, discharged from the fuel gas chamber on the hydrogen electrode side of the fuel cell 104 (after some of the condensed water has been removed by the drain Db) at a high pressure state of a predetermined set pressure (for example, 3 to 10 atmospheres).

[0050] Specifically, this pressure controller PCc may be equipped with a back pressure valve and a pressure gauge, and the back pressure on the hydrogen electrode side within the fuel cell 104 may be controlled by adjusting this back pressure valve. Hereafter, the "back pressure" value on both the hydrogen electrode side and the air electrode side will be set to 1 atmosphere (approximately 0.1 MPa) when the exhaust side of the fuel cell 104 is open, i.e., when the exhaust gas pressure is atmospheric pressure.

[0051] Also in Figure 1, the hydrogen recovery unit U129 is a unit for extracting unreacted residual hydrogen gas from the exhaust gas that comes out via the pressure controller PCc, using, for example, a known hydrogen gas filter or executor, and reusing it. In this embodiment, the extracted hydrogen gas is sent back to the hydrogen mixer Ma downstream of the flow controller FCb. The gas after the hydrogen gas has been extracted may be discharged to the outside.

[0052] Furthermore, it is preferable that the hydrogen recovery U129 undergoes a dehumidification treatment to remove any remaining water vapor or moisture from the exhaust gas that has come out via the pressure controller PCc as a pretreatment for the removal of unreacted residual hydrogen gas. Here, it is also preferable that this dehumidification treatment be carried out by a dehumidifier using silica gel or zeolite, a dehumidification device equipped with a pressurization mechanism, a gas-liquid separator such as a gravity separation type, centrifugal separation type, mist remover pad type, airfoil separation type or pressure separation coalescer type, and a dry filter device.

[0053] <Fuel cell unit> Similarly, in Figure 1, the fuel cell U103 is equipped with a fuel cell 104, and in this embodiment, (a) Humid, high-pressure air humidified by a water exchange dehumidifier U105, having a pressure greater than or equal to the above-mentioned "pressure threshold," for example, a high pressure of 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa) in this embodiment, (b) High-pressure hydrogen gas supplied from a flow controller FCb (gas reformer U121) at a pressure equivalent to the high-pressure air in (a) above, for example, a high pressure of 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa) These gases are received from the air intake on the air electrode side and the hydrogen intake on the hydrogen electrode side of the fuel cell 104, respectively, and introduced into the oxidizing gas chamber and fuel gas chamber, respectively, to trigger the fuel cell reaction.

[0054] Next, as a result of this fuel cell reaction, exhaust gas is released from the exhaust gas outlet on the air electrode side and the exhaust gas outlet on the hydrogen electrode side of the fuel cell 104, respectively. (c) A high-pressure exhaust gas having a pressure greater than or equal to the "pressure threshold" mentioned above, for example, a high pressure of 3 to 10 atmospheres (approximately 0.3 to 0.1 MPa) in this embodiment, and having an oxygen concentration lower than that of air, (d) High-pressure exhaust gas having the same pressure as the exhaust gas in (c) above It discharges.

[0055] Here, the high-pressure exhaust gas described in (c) above has some of the condensation removed in drain Da, and then its temperature is adjusted in temperature controller TCa to a temperature suitable for the subsequent water exchange dehumidification process before being supplied to water exchange dehumidifier U105 for dehumidification. Furthermore, it undergoes nitrogen filtering and other processes before finally being converted into high-purity nitrogen gas, which is the result of device (system) 1. In any case, this high-pressure exhaust gas is usually a gas with a relative humidity of approximately 100%, and the subsequent dehumidification process by water exchange dehumidifier U105, etc., is extremely important. Incidentally, in this embodiment, since the exhaust gas is under high pressure, its dew point is considerably high, and the amount of water that falls into drains Da and Db increases accordingly. In other words, a higher level of dehumidification is performed in drains Da and Db as well.

[0056] Furthermore, as described above, by increasing the input and output pressure of the fuel cell 104, the fuel cell reaction is accelerated, and as a result, high-pressure exhaust gas with a lower oxygen concentration can be extracted. Also, as will be described in detail later as one embodiment, High-pressure gas supply U101 as an air supply source, high-pressure water electrolysis U125 as a hydrogen supply source (explained later using Figure 5), fuel cell U103, water exchange dehumidification U105, dry filtering U107, catalytic combustion U108 (explained later using Figures 4 and 5), and nitrogen filtering U109 By connecting all of these through the exchange of high-pressure gas, it becomes possible to generate high-pressure air to high-pressure, high-purity nitrogen gas with high efficiency in a single, continuous flow of high pressure within the entire apparatus (system) 1.

[0057] Furthermore, the fuel cell 104 can have a known configuration, for example, a configuration in which multiple cells, each having a structure in which an electrolyte layer is sandwiched between an air electrode (oxygen electrode, cathode) and a hydrogen electrode (fuel electrode, anode), are stacked (laminated) with a separator in between. In other words, each cell has a structure in which an oxidizing gas chamber on the air electrode side and a fuel gas chamber on the hydrogen electrode side are provided so as to sandwich the electrolyte layer.

[0058] Furthermore, while fuel cell 104 is a polymer electrolyte fuel cell (PEFC) in this embodiment, it can of course also be a solid oxide fuel cell (SOFC), a phosphoric acid fuel cell (PAFC), or a molten carbonate fuel cell (MCFC). Incidentally, the PEFC used in this embodiment operates at relatively low temperatures and allows for a compact battery size, and is therefore used in many fuel cell vehicles, for example.

[0059] In the fuel cell 104 employing this PEFC method, the solid polymer membrane (electrolyte layer) must be kept in a moist state in order to maintain high proton conductivity and continue a good fuel cell reaction. In this regard, the high-pressure air introduced into the fuel cell 104 as described in (a) above is moist air that has been humidified by the water exchange dehumidifier U105. As a result, the solid polymer membrane (electrolyte layer) can maintain a moist state by receiving moisture and water vapor from this moist high-pressure air, thereby enabling a stable supply of exhaust gas with sufficient oxygen consumption.

[0060] Furthermore, in this embodiment, as described above, the fuel cell 104 is a high-pressure type that receives the high-pressure (e.g., 3 to 10 atmospheres) air described in (a) and the high-pressure (e.g., 3 to 10 atmospheres) hydrogen gas described in (b), and discharges high-pressure (e.g., 3 to 10 atmospheres) exhaust gas from the oxidation gas chamber described in (c) and high-pressure (e.g., 3 to 10 atmospheres) exhaust gas from the fuel gas chamber described in (d). Here, the pressure in these oxidation gas chamber and fuel gas chamber, i.e., the back pressure (e.g., 3 to 10 atmospheres), is set and adjusted by a pressure controller PCa equipped with a back pressure valve and a pressure controller PCc equipped with a back pressure valve, respectively. In order to prevent damage to the electrolyte layer of the fuel cell 104, it is also preferable that the back pressure of the oxidation gas chamber and the back pressure of the fuel gas chamber be set to be equivalent with an error of, for example, less than 0.1 atmospheres (approximately 0.01 MPa). Furthermore, if the back pressure on the oxidizing gas chamber side (air electrode side) can be controlled by the pressure controller PCd, described later, which is located downstream of the nitrogen filter U109, the pressure controller PCa can be omitted.

[0061] Incidentally, as a high-pressure fuel cell, it is also preferable to use a fuel cell with an input pressure of 9 atmospheres (approximately 0.9 MPa) and a rated output of several tens of kilowatts (for example, 70 kW). By employing a fuel cell with a high output, the amount of exhaust gas extracted increases, and it becomes possible to increase the amount (flow rate) of high-purity nitrogen gas that is ultimately produced.

[0062] Furthermore, it is preferable that the fuel cell U103 equipped with the fuel cell 104 as described above is also equipped with a group of measuring devices and sensors capable of measuring (a) the flow rate, pressure, and temperature of the high-pressure air or high-pressure hydrogen gas taken into the fuel cell 104, (b) the flow rate, pressure, and temperature of the exhaust gas or water vapor / moisture discharged from the fuel cell 104, and (c) the complex impedance between the hydrogen electrode and the air electrode of the fuel cell 104. It is also preferable that the operation of the fuel cell 104 is appropriately controlled by the overall control U131 which receives the measurement information from the group of measuring devices and sensors.

[0063] For example, as a simple control example, a fuel cell control (machine learning) model using a DNN (Deep Neural Network) algorithm or the like may be constructed with (b) and (c) above as explanatory variables and (a) above as the objective variable, and the flow rate, pressure, and / or temperature of the hydrogen gas or air supplied to the fuel cell 104 may be adjusted using this constructed model so that the fuel cell 104 produces the desired output.

[0064] Furthermore, it is preferable that the fuel cell U103 has a heat exchanger that circulates a heat exchange medium such as water, placed inside or around the fuel cell 104, to extract heat from the operating fuel cell 104 that generates heat, and transfer it to the outside of the unit. Examples of usable heat exchangers include multi-tube heat exchangers such as shell-and-tube heat exchangers, and plate heat exchangers such as Alfa Laval brazed plate heat exchangers. Alternatively, instead of a heat exchanger, it is also possible to directly extract heat from inside the fuel cell 104 to the outside using a heat conduction system that connects a conductive separator and a heat pipe in the fuel cell 104. In any case, such heat transfer means can control the temperature of the cells of the fuel cell 104 to a predetermined temperature (e.g., 80°C) or lower, and maintain optimal operation of the fuel cell 104.

[0065] Here, the heat transferred by the heat transfer means such as the heat exchanger and heat conduction system described above is, in this embodiment, (a) A temperature controller TCa that adjusts the temperature of the high-pressure exhaust gas supplied to the water exchange dehumidifier U105, and (b) Temperature controller TCb for adjusting the temperature of the high-pressure exhaust gas supplied to the nitrogen filter U109 The heat is sent to a pressure adjustment unit PCb equipped with an off-gas buffer tank (described later) and used to adjust the temperature of the high-pressure exhaust gas. For example, it is preferable to adjust the temperature by changing the temperature of the metal tube through which the high-pressure exhaust gas passes using this heat. Furthermore, it is also preferable to send this heat to a pressure adjustment unit PCb equipped with an off-gas buffer tank (described later) and use it to adjust the temperature of the exhaust gas in the tank. In addition, it is also possible to use the heat transferred from the fuel cell 104 to provide the heat required for steam reforming in the gas reformer U121.

[0066] Furthermore, it is preferable that the fuel cell U103 supplies the electricity generated by the fuel cell 104 to the high-pressure gas supply U101, and that the high-pressure gas supply U101 operates its own compressor using this electricity or using this electricity in conjunction with commercial power. This makes it possible to suppress (or reduce to approximately zero) the power supply to the entire device (system) 1.

[0067] In another embodiment, the fuel cell U103 may be configured such that two or more fuel cells 104 are connected in series, and each subsequent fuel cell 104 sequentially takes in the exhaust gas from the previous fuel cell 104 and uses it in the fuel cell reaction, ultimately producing exhaust gas with a lower oxygen concentration (for example, exhaust gas with an oxygen concentration of 2.5 vol% or less). Incidentally, the inventors of this application have published a fuel cell system with such a configuration in Japanese Patent Application Publication No. 2019-129110.

[0068] Herein, the fuel cell 104 of this embodiment described above is a fuel cell that can handle high pressure (for example, 3 to 10 atmospheres), but it is also possible to use a normal fuel cell that handles gas at less than 3 atmospheres (or 2 atmospheres). In this case, the high-pressure gas supply U101 and the pressure boosting U123 can be used to supply air or hydrogen gas at less than 3 atmospheres (or 2 atmospheres), or they may be omitted depending on the gas pressure to be introduced into the fuel cell 104.

[0069] In this case, the water exchange dehumidifier U105 performs water exchange between the intake air, for example, at less than 3 atmospheres (or 2 atmospheres), and the exhaust gas, for example, at less than 3 atmospheres (or 2 atmospheres), extracted from the fuel cell 104, thereby reducing the moisture or water vapor content in the exhaust gas. Of course, even in this case, as will be explained in detail later, it is possible to reliably carry out the dehumidification process by adjusting the temperature difference between the air and the exhaust gas.

[0070] In the following, such fuel cells will be referred to as "conventional gas pressure type" fuel cells, and embodiments using this "conventional gas pressure type" fuel cell 104 will be described as appropriate.

[0071] <Dry filtering means> Also in Figure 1, the dry filtering U107 in this embodiment is equipped with a dry filter 107F and is a dehumidification means that further reduces the moisture or water vapor content in the high-pressure (e.g., 3 to 10 atmospheres) exhaust gas taken out from the water exchange dehumidification U105.

[0072] As shown in Figure 1, the dry filter 107F of this embodiment is a filter that introduces high-pressure exhaust gas into a hollow fiber membrane 107Fa from an inlet of the hollow fiber membrane 107Fa, which allows more water vapor to pass through compared to air, and extracts dry exhaust gas with further reduced moisture or water vapor content from the outlet of the hollow fiber membrane 107Fa. Here, a portion of the extracted dry exhaust gas (for example, 10-20%) is returned to the surface side of the hollow fiber membrane 107Fa and used as a purge gas to capture the water vapor that has permeated through the hollow fiber membrane 107Fa and release it outside the filter. In a modified form, it is also possible to use compressed air supplied from an external source (for example, deployed in the factory) as this purge gas instead of a portion of the generated dry exhaust gas.

[0073] Furthermore, the hollow fiber membrane 107Fa described above can be, for example, a fluorine-based non-porous membrane with high affinity for water molecules. In any case, a force acts on the hollow fiber membrane 107Fa to eliminate the difference in moisture concentration between the exhaust gas flowing inside the membrane and the purge gas flowing outside the membrane, and as a result, moisture and water vapor move from the exhaust gas to the purge gas.

[0074] In the dry filter 107F described above, experiments have confirmed that the higher the pressure of the introduced high-pressure exhaust gas (inlet pressure) and the lower the flow rate of the introduced high-pressure exhaust gas (filter inlet flow rate), the lower the relative humidity (i.e., the lower the dew point) of the exhaust gas that can be extracted from the filter outlet. For example, when exhaust gas with a relative humidity of 100% was introduced into a hollow fiber membrane type dry filter under the condition of a filter inlet flow rate of 100 liters (L) / min, the relative humidity of the resulting dry exhaust gas was 55% when the inlet pressure was 2 atmospheres (approximately 0.2 MPa) and 33% when the inlet pressure was 4 atmospheres (approximately 0.4 MPa). Furthermore, when the inlet pressure was 4 atmospheres (approximately 0.4 MPa) and the filter inlet flow rate was set to 50 L / min, the relative humidity of the resulting dry exhaust gas decreased to 20%.

[0075] Incidentally, for example, if a dry filter is used that can extract dry gas with a dew point of -60°C at atmospheric pressure, under conditions where the introduction pressure is 9 atmospheres (approximately 0.9 MPa), the filter inlet flow rate is 520 L / min, and the outlet flow rate is 280 L / min (i.e., the yield is 54%), then by using N of these dry filters (for example, 3) arranged in parallel, it is possible to generate such dry exhaust gas at a flow rate of 280 × N (840 if N=3) L / min.

[0076] In this embodiment, it has been explained that the dry filter U107 further reduces the moisture or water vapor content in high-pressure (e.g., 3 to 10 atmospheres) exhaust gas. Here, in this embodiment, this high pressure value is greater than or equal to the "lower limit pressure" required or determined by the dry filter 107F itself (not just the nitrogen gas filter 109F of the nitrogen filter U109 that passes through thereafter). Here, this "lower limit pressure" is a pressure value that significantly exceeds atmospheric pressure (1 atmosphere, approximately 0.1 MPa) determined by the filter characteristics, and is usually set to a high pressure value of at least 3 atmospheres (approximately 0.3 MPa) or higher.

[0077] For example, when using a dry filter 107F in order to extract dry exhaust gas at a desired flow rate with a desired low relative humidity, the introduction pressure should be 9 atmospheres (approximately 0.9 MPa) or higher (i.e., the "lower limit pressure" should be 9 atmospheres (approximately 0.9 MPa)), the exhaust gas introduced into the dry filter U107 can be a gas with a pressure of, for example, 9 to 9.5 atmospheres (approximately 0.9 to 0.95 MPa). Incidentally, in this case, it is also preferable that the high-pressure gas supply U101, which is the source of the high-pressure air, generates high-pressure air with a pressure of, for example, 9.5 atmospheres (approximately 0.95 MPa) or higher, which is a "pressure threshold" set based on this "lower limit pressure" (9 atmospheres) (taking into account the pressure loss within the device (system) 1).

[0078] As described above, the high-pressure fuel cell 104 and the dry filtering U107, when combined into a single high-pressure system, are a very suitable combination because they can efficiently remove moisture and water vapor generated while promoting the efficiency of the battery reaction. However, if the dehumidification of the high-pressure exhaust gas is sufficiently carried out by the preceding water exchange dehumidification U105, for example, if the relative humidity of the high-pressure exhaust gas is reduced by the water exchange dehumidification U105 to a level where it is acceptable to supply it to the nitrogen filtering U109 (to a level where nitrogen filtering is effectively carried out), the dry filtering U107 can be omitted.

[0079] The above describes an embodiment equipped with a high-pressure fuel cell 104 and a dry filtering U107. However, in this device (system) 1, it is also possible to adopt an embodiment using a "normal gas pressure type" fuel cell 104 and a dry filtering U107. In this case, as shown in Figure 1, a "pressure adjustment unit PCb" may be provided before the dry filtering U107.

[0080] This pressure adjustment unit PCb adjusts the pressure of the exhaust gas taken out of the water exchange dehumidifier U105 to a pressure equal to or greater than the "pressure threshold" set based on the lower pressure limit required or determined in the nitrogen filter U109 (here, in the dry filter U107 and nitrogen filter U109). For example, it adjusts the pressure of the exhaust gas taken out of the water exchange dehumidifier U105 to be equal to or greater than the inlet pressure set in the dry filter U107 (e.g., 9 atmospheres).

[0081] Specifically, the pressure adjustment unit PCb may include a compression pump, a booster pump, or a gas-driven pressure boosting valve, and an off-gas buffer tank equipped with a gas pressure gauge. The exhaust gas removed from the water exchange dehumidification U105 is pressurized to a pressure equal to or greater than the introduction pressure set in the dry filtering U107, introduced into the off-gas buffer tank, and temporarily stored. Here, (although a high-pressure gas supply U101 is provided as described above) it is also preferable to draw in a portion of the high-pressure air from the high-pressure gas supply U101 and thereby drive the pressure boosting valve.

[0082] Furthermore, it is preferable that the off-gas buffer tank of the pressure adjustment unit PCb receives heat transferred from the fuel cell U103 via heat transfer means such as a heat exchanger or heat conduction system, and raises the temperature of the exhaust gas in the tank to a temperature higher than room temperature. This makes it possible to supply exhaust gas at a temperature within a temperature range suitable for dry filtering to the dry filter 107F of the dry filtering U107. Of course, if the temperature of the exhaust gas taken out from the water exchange dehumidification U105 is within a temperature range suitable for dry filtering, heating treatment of the exhaust gas in the off-gas buffer tank is unnecessary.

[0083] Here, by employing the pressure adjustment unit PCb described above, it becomes possible to utilize the nitrogen filtering U109 and catalytic combustion U108, which will be described in detail later, even in this embodiment using the "normal gas pressure type" fuel cell 104.

[0084] Furthermore, such a pressure adjustment unit PCb can also be used in embodiments that utilize a high-pressure compatible fuel cell 104. For example, if the pressure of the exhaust gas introduced into the dry filtering U107 does not reach the introduction pressure set in the dry filtering U107 (e.g., 9 atmospheres) due to the original settings or pressure loss along the way, it is preferable for the pressure adjustment unit PCb to compensate for the pressure deficiency. Of course, if such pressure adjustment is not necessary, this pressure adjustment unit PCb may be omitted.

[0085] <Nitrogen filtering means> Also in Figure 1, the nitrogen filter U109 in this embodiment is a means of converting the high-pressure (e.g., 3 to 10 atmospheres) exhaust gas (removed from the dry filter U107) with reduced moisture or water vapor content into a gas with increased nitrogen concentration, or in this embodiment, high-purity nitrogen gas, using the nitrogen gas filter 109F.

[0086] Specifically in this embodiment, the nitrogen gas filter 109F of the nitrogen filter U109 is (a) Hollow fiber sections with different degrees of permeability to nitrogen and oxygen (109Fa in Figure 3), (b) A filter inlet (109Fb in Figure 3) for introducing high-pressure exhaust gas (e.g., 3 to 10 atmospheres) to act upon the hollow fiber section of the nitrogen gas filter 109F, and a filter outlet (109Fc in Figure 3) for extracting exhaust gas with increased nitrogen concentration (high-purity nitrogen gas) from this hollow fiber section, (c) A filter purge section (109Fd in Figure 3) separates the gas containing oxygen molecules separated from nitrogen molecules (in the exhaust gas) by the hollow fiber section of the nitrogen gas filter 109F (hereinafter abbreviated as filter exhaust gas) from the exhaust gas (high-purity nitrogen gas) extracted in (b) above. It is equipped with.

[0087] Of these, the hollow fiber section of the nitrogen gas filter 109F is made of hollow polymer fibers that preferentially allow oxygen molecules to pass through rather than nitrogen molecules. As high-pressure exhaust gas (e.g., 3 to 10 atmospheres) flows from the filter inlet through this hollow fiber section, oxygen molecules selectively permeate through these polymer fibers and exit, so that high-purity nitrogen gas is ultimately extracted from the filter outlet.

[0088] Furthermore, experiments have confirmed that in such hollow fiber sections, the higher the pressure of the introduced high-pressure exhaust gas (introduction pressure), the lower the flow rate of the extracted high-pressure exhaust gas (high-purity nitrogen gas) (outlet flow rate), and the lower the oxygen concentration of the introduced high-pressure exhaust gas (introduction oxygen concentration), the more gas with a lower oxygen concentration (outlet oxygen concentration) (i.e., a higher nitrogen concentration) can be extracted from the filter outlet.

[0089] From the perspective of the dependence of the outlet oxygen concentration on the input oxygen concentration, it can be seen that the fuel cell 104, which emits exhaust gas with a low oxygen concentration, and the nitrogen gas filter 109F, which filters this exhaust gas, are a very suitable combination for producing high-purity nitrogen gas. Furthermore, experiments have confirmed that the recovery rate (= outlet flow rate / input flow rate) increases as the input oxygen concentration decreases. Therefore, from the perspective of recovery rate, the fuel cell 104 and the nitrogen gas filter 109F are a suitable combination capable of recovering a sufficient amount of high-purity nitrogen gas.

[0090] Specifically, for the nitrogen gas filter 109F, we can use, for example, UBE N2 separators manufactured by Ube Industries using polyimide hollow fibers, SEPURAN N2 membrane modules manufactured by Daicel-Evonik, or selective type nitrogen gas filters also manufactured by Daicel-Evonik.

[0091] In this embodiment, it has been explained that the nitrogen gas filter 109F further reduces the oxygen concentration in exhaust gas at high pressure (e.g., 3 to 10 atmospheres). Here, in this embodiment, this high pressure value is equal to or greater than the "lower limit pressure" required or determined for the dry filter 107F. Here, as mentioned above, this "lower limit pressure" is a pressure value that significantly exceeds atmospheric pressure (1 atmosphere, approximately 0.1 MPa) determined by the filter characteristics, and is usually set to a high pressure value of at least 3 atmospheres (approximately 0.3 MPa) or higher.

[0092] For example, when using a nitrogen gas filter 109F in order to extract nitrogen gas (exhaust gas) at a desired flow rate with a desired low oxygen concentration, the introduction pressure should be 8 atmospheres (approximately 0.8 MPa) or higher (i.e., the "lower limit pressure" should be 8 atmospheres (approximately 0.8 MPa)), the exhaust gas introduced into the nitrogen gas filter 109F can be a gas with a pressure of, for example, 8 to 8.5 atmospheres (approximately 0.8 to 0.85 MPa). Incidentally, in this case, it is also preferable that the high-pressure gas supply U101, which is the source of the high-pressure air, generates high-pressure air with a pressure of, for example, 8.5 atmospheres (approximately 0.85 MPa) or higher, which is a "pressure threshold" set based on the "lower limit pressure" (8 atmospheres) (taking into account the pressure loss within the device (system) 1) (for example, 9.5 atmospheres (approximately 0.95 MPa) or higher (as mentioned above, taking into account the requirements of the dry filter 107F).

[0093] Here is one example. Using a UBE N2 separator NM-B01A manufactured by Ube Industries as the nitrogen gas filter 109F, a nitrogen-oxygen mixed gas with a temperature of 50°C and an oxygen concentration of 5.1 vol% was introduced to this nitrogen gas filter 109F at an introduction pressure of 7.0 atmospheres (approximately 0.7 MPa). When the outlet flow rate was set to 1.0 L / min, high-purity nitrogen gas with an oxygen concentration of approximately 1000 ppm vol (0.1 vol%) was obtained. Furthermore, when a nitrogen-oxygen mixed gas with an oxygen concentration of 1.1 vol% was introduced under the same conditions, high-purity nitrogen gas with an oxygen concentration of approximately 300 ppm vol (0.03 vol%) was obtained.

[0094] As described above, the high-pressure fuel cell 104, dry filter U107, and nitrogen filter U109, by forming a high-pressure through-system with respect to pressure (gas pressure), efficiently remove moisture and water vapor generated while promoting the efficiency of the battery reaction, and further reduce the oxygen concentration in the exhaust gas. Therefore, this combination is very suitable for producing high-purity nitrogen gas. For example, the exhaust gas pressure of 8 to 10 atmospheres (approximately 0.8 to 10 MPa) may be controlled to be consistently maintained by a pressure controller PCa, a pressure adjustment unit PCb, or a pressure controller PCd, which will be described later.

[0095] However, as mentioned above, if the relative humidity of the high-pressure exhaust gas is reduced by the water exchange dehumidification U105 to a level where it is acceptable to supply it to the nitrogen filter U109 (to a level where nitrogen filtering can be effectively performed), then the dry filter U107 does not need to be provided. Incidentally, experiments have confirmed that with a certain nitrogen gas filter 109F, good nitrogen filtering can be performed with high-pressure exhaust gas with a relative humidity of approximately 20%, and it is also possible to perform nitrogen filtering even with high-pressure exhaust gas with a relative humidity of approximately 60%.

[0096] Furthermore, the fuel cell 104, dry filter U107, and nitrogen filter U109 are an extremely suitable combination from the standpoint of minimizing the hydrogen gas content in the nitrogen gas generated from the exhaust gas and providing higher purity nitrogen gas. In fact, the high-pressure exhaust gas discharged from the air electrode side (oxidation gas chamber side) of the fuel cell 104 usually contains hydrogen gas leaked from the fuel gas chamber on the hydrogen electrode side, or hydrogen gas as residual purge gas, sometimes amounting to about 1-3 vol%.

[0097] In contrast, most hollow fiber membranes that can be used in the dry filter 107F have the property of selectively permeating not only water vapor (H2O) but also hydrogen (H2) more effectively than nitrogen (N2). By using a dry filter 107F having a hollow fiber membrane 107Fa with such properties, it is possible to significantly reduce or nearly eliminate the hydrogen gas content in high-pressure exhaust gas.

[0098] Furthermore, many of the hollow fiber materials that can be used in the nitrogen gas filter 109F also have the property of selectively permeating not only oxygen (O2) but also hydrogen (H2) more effectively than nitrogen (N2). By using a nitrogen gas filter 109F having a hollow fiber section (109Fa in Figure 3) with such properties, it is possible to significantly reduce or nearly eliminate the hydrogen gas content in high-pressure exhaust gas.

[0099] The following describes the various instruments and devices installed before the nitrogen filter U109.

[0100] Also shown in Figure 1, the various filter units FLa are units that treat the high-pressure exhaust gas supplied to the nitrogen filter U109 to remove or reduce sulfides, chlorides, hydrocarbons, fluorides, and strong alkaline compounds that are harmful to the hollow fiber portion of the nitrogen gas filter 109F. Specifically, the various filter units FLa are equipped with, for example, activated carbon filters to remove or reduce the above-mentioned impurities in the exhaust gas. Furthermore, it is preferable that the various filter units FLa also be equipped with mist filters and dust filters to remove or reduce mist such as water mist, solvent mist, and oil mist in the exhaust gas.

[0101] Also in Figure 1, the temperature controller TCb is a device for supplying temperature-controlled high-pressure exhaust gas to the nitrogen filter U109 by bringing the temperature of the incoming high-pressure exhaust gas close to or matching a preset suitable temperature (e.g., 35-60°C) based on the characteristics of the nitrogen gas filter 109F. In this embodiment, it is also preferable that the temperature controller TCb adjusts the temperature by changing the temperature of the metal tube through which the high-pressure exhaust gas passes, for example, by using heat transferred from the fuel cell U103 by a heat transfer means such as a heat exchanger or a heat conduction system. Alternatively, it may be equipped with an electric heater, and the exhaust gas temperature may be adjusted by the power supplied from the fuel cell U103. Of course, if the temperature of the exhaust gas supplied to the nitrogen filter U109 is sufficiently high, this temperature controller TCb can also be omitted.

[0102] Here, the temperature controllers TCa and TCb described above are means of controlling the temperature of the high-pressure exhaust gas taken from the fuel cell 104, and the temperature of the high-pressure exhaust gas before it is taken into the nitrogen filter U109, to a temperature above a "temperature threshold" (e.g., 60°C and 50°C) set based on the "lower limit temperature" required or determined in the water exchange dehumidification U105 and the nitrogen filter U109. In other words, they are means of adjusting the exhaust gas temperature in a consistent manner throughout the entire device (system) 1. For example, the temperature may be adjusted to consistently maintain an exhaust gas temperature of 60-80°C.

[0103] Furthermore, as mentioned above, it is also preferable that these temperature controllers TCa and TCb use heat from the fuel cell 104 (heat transferred by heat transfer means such as heat exchangers and heat conduction systems) to control the temperature of the high-pressure exhaust gas to a temperature above the "temperature threshold." The "lower limit temperature" in the water exchange dehumidification U105 will be explained in detail later using Figure 2.

[0104] Next, we will explain the various instruments and devices installed downstream of the nitrogen filter U109.

[0105] Similarly, in Figure 1, pressure controller PCd, like pressure controller PCa, is equipped with a back pressure valve and controls the outlet pressure (pressure of the extracted nitrogen gas) at nitrogen filter U109, i.e., the back pressure. In this embodiment, it plays a role in introducing high-pressure exhaust gas (e.g., 3 to 10 atmospheres) with a pressure above the "pressure threshold" into dry filter U107 and nitrogen filter U109. In other words, pressure controller PCd is a pressure control means for maintaining at least the dry filter U107 to nitrogen filter U109 as a series of high-pressure systems. Furthermore, in this embodiment, which employs a high-pressure compatible fuel cell 104, it plays a role in maintaining the fuel cell U103 (fuel cell 104) through dry filter U107 to nitrogen filter U109 as a series of high-pressure systems. Incidentally, in this case, as mentioned above, pressure controller PCa can be omitted.

[0106] Also in Figure 1, the flow controller FCc is a device that controls the flow rate of the high-pressure exhaust gas with increased nitrogen concentration generated by the nitrogen filter U109, which in this embodiment is high-pressure, high-purity nitrogen gas, and supplies this high-purity nitrogen gas at a predetermined flow rate to a nitrogen gas tank outside the system 1 or to equipment that requires high-purity nitrogen gas. Specifically, this flow controller FCc can be equipped with a gas regulator and a mass flow controller (or flow switch).

[0107] In any case, in this embodiment, the high-purity nitrogen gas produced by the apparatus (system) 1 is under high pressure, and can be supplied as is to destinations that require high-pressure nitrogen gas, while it can be supplied to destinations that do not require high pressure after being reduced in pressure using a pressure reducing valve or the like. Furthermore, it is preferable for the overall control unit U131 to check the measurement data received from the oxygen concentration meter Oa and gas pressure meter Pa, which are located downstream of the nitrogen filter U109, and to check whether the quality (low oxygen concentration) and gas pressure of the high-purity nitrogen gas supplied externally meet the specifications.

[0108] Furthermore, as described above, the nitrogen gas generation apparatus (system) 1 of this embodiment can generate not only high-purity nitrogen gas, but also electricity, heat (energy), and water (pure water), and can provide these as results to external parties. In other words, it functions as a nitrogen gas, electricity, heat, and water supply apparatus (system).

[0109] Here, we will describe the applications and usage methods of the high-purity nitrogen gas produced by the nitrogen gas generator (system) 1. As mentioned above, there is a great demand for high-purity nitrogen gas in various production and service provision sites. For example, it is an indispensable gas as a reducing atmosphere in various furnaces such as atmosphere furnaces, reflow soldering equipment, flow soldering equipment, and even in fryers.

[0110] Furthermore, in many cases, "nitrogen gas mixed with a predetermined amount of hydrogen gas" is used as such a reducing atmosphere. The nitrogen gas generator (system) 1 can provide such "nitrogen gas mixed with a predetermined amount of hydrogen gas" by using hydrogen gas that remains (or is intentionally left behind) in the exhaust gas discharged from the fuel cell 104, by mixing in hydrogen gas produced by gas reforming U121 or high-pressure water electrolysis U125 (Figure 5), which will be explained later, or by using hydrogen gas that remains (or is intentionally left behind) after catalytic combustion treatment in catalytic combustion U108, which will be explained later.

[0111] Furthermore, the high-purity nitrogen gas produced by the nitrogen gas generator (system) 1 can also be used as a means of removing or reducing dissolved oxygen in water or oil. For example, deoxygenation treatment is necessary to remove or reduce the amount of oxygen (O2) normally dissolved in water and oil for purposes such as mold cooling water, semiconductor cleaning water, circulating water for various heat storage tanks, boiler feedwater, air conditioning cooling water, edible water used in the production of juices, teas, beers, etc., edible oil, frying oil used in fryers, and water and oil used as raw materials for various chemical products, in order to prevent rust in pipes, for the manufacturing and processing processes of manufactured and processed products, and to maintain the quality of manufactured and processed products.

[0112] Specifically, this deoxygenation treatment involves blowing high-purity nitrogen gas, for example, 3N (nitrogen concentration 99.9 vol%), into the target material, such as water. When high-purity nitrogen gas is blown into water in this way, nitrogen (N2) and oxygen (O2) move across the gas-liquid interface to reach equilibrium according to Henry's Law. As a result, dissolved oxygen in the water is mixed as oxygen gas into the bubbles of the blown-in high-purity nitrogen gas, and is ultimately released into the water along with these bubbles.

[0113] Thus, by using the high-purity nitrogen gas produced by the nitrogen gas generator (system) 1, it becomes possible to safely and reliably remove or reduce oxygen (O2) dissolved in water or oil without using chemicals, for example.

[0114] [Water exchange dehumidification U105] Figure 2 is a schematic diagram showing one embodiment of the combination of the water exchange dehumidification means and fuel cell according to the present invention.

[0115] First, the water exchange dehumidifier U105 of this embodiment shown in Figure 2(A) is equipped with a humidification chamber 105H and a dehumidification chamber 105D with a water vapor exchange membrane 105V in between, and in this embodiment, (a) High-pressure (e.g., 3-10 atmospheres) air introduced from high-pressure gas supply U101 to humidification chamber 105H via flow controller FCa, (b) High-pressure (e.g., 3-10 atmospheres) exhaust gas introduced from the oxidizing gas chamber 104X of the fuel cell 104 to the dehumidifying chamber 105D via the temperature controller TCa and Water exchange is performed via a water vapor exchange membrane 105V between these points to reduce the moisture or water vapor content in the high-pressure exhaust gas described in (b) above.

[0116] Here, the water vapor exchange membrane 105V plays the role of receiving water vapor (H2O) from the high-pressure exhaust gas flowing through the dehumidification chamber 105D, allowing it to pass through, and transferring it to the high-pressure air flowing through the humidification chamber 105H. This membrane permeation and transfer process of water vapor is an endothermic reaction, and in order for this process (endothermic reaction) to proceed, the temperature of the high-pressure exhaust gas flowing through the dehumidification chamber 105D must be maintained at a higher temperature than the temperature of the high-pressure air flowing through the humidification chamber 105H.

[0117] Furthermore, the progress of this membrane permeation and migration process depends not only on the partial pressure of water vapor in both (and also on the flow rates of both), but also on the temperature difference between them, as it is an endothermic reaction. Therefore, the temperature of the high-pressure exhaust gas needs to be set to a sufficiently high temperature. In this regard, the temperature of the exhaust gas discharged from the fuel cell 104 is typically around 55-80°C in the case of a PEFC, which is sufficiently high compared to high-pressure air, which is typically at room temperature (e.g., 25°C). For example, it has been found that if this temperature difference is maintained, approximately 30% of the moisture and water vapor in the high-pressure exhaust gas can be transferred to the high-pressure air.

[0118] Incidentally, the pressure of the high-pressure air in (a) above (e.g., 3 to 10 atmospheres) and the pressure of the high-pressure exhaust gas in (b) above (e.g., 3 to 10 atmospheres) are both controlled by the pressure controller PCa (Figure 1) installed downstream of the water exchange dehumidifier U105, and due to the configuration of the flow path, they are approximately the same. Therefore, damage to the water vapor exchange membrane 105V due to the applied high pressure can be avoided.

[0119] As mentioned above, the membrane permeation and transfer process of water vapor (H2O) in the water vapor exchange membrane 105V is a reaction that continuously absorbs heat, so it is necessary to maintain a state in which the temperature difference between the high-pressure air in (a) and the high-pressure exhaust gas in (b) is above a predetermined level. For this reason, in this embodiment, gas thermometers Tc and Td, and gas thermometers Ta and Tb are installed in the preceding and succeeding stages of the humidifying chamber 105H into which high-pressure air is introduced and taken out, and in the preceding and succeeding stages of the dehumidifying chamber 105D into which high-pressure exhaust gas is introduced and taken out.

[0120] The overall control unit U131 monitors the temperatures of these gas thermometers and adjusts the amount of high-pressure air introduced by the flow controller FCa so that the above temperature difference is above a predetermined level, and further adjusts the temperature of the high-pressure exhaust gas by the temperature regulator TCa. This makes it possible to reliably produce high-pressure exhaust gas that has undergone dehumidification (relative humidity reduced to below the target value). The humidified high-pressure air is supplied to the oxidation gas chamber 104X of the fuel cell 104, wetting the electrolyte layer 104E provided between it and the fuel gas chamber 104H, thereby continuing a good fuel cell reaction.

[0121] Here, the temperature controller TCa mentioned above is a means of controlling the temperature of the high-pressure exhaust gas taken from the fuel cell 104 to a temperature above a "temperature threshold" (e.g., 60°C) that is set based on the "lower limit temperature" required or determined in the water exchange dehumidification U105. Furthermore, this "lower limit temperature" is a temperature value determined from the minimum "temperature difference" (between the high-pressure exhaust gas and the high-pressure air) required to achieve the dehumidification effect (reduction of relative humidity) set in the water exchange dehumidification U105. For example, if the temperature of the high-pressure air is 25°C and the minimum required "temperature difference" is 30°C, then the "lower limit temperature" will be 55 (=25+30)°C.

[0122] The above describes one embodiment of the water exchange dehumidifier U105. As this water exchange dehumidifier U105, for example, a Perma Pure humidifier equipped with a Nafion® membrane tube as the water vapor exchange membrane 105V can be used.

[0123] The above describes the combination of the high-pressure compatible fuel cell U103 (fuel cell 104) and the water exchange dehumidifier U105 that handles high-pressure gas. Now, a preferred embodiment of this high-pressure compatible fuel cell 104 will be described.

[0124] As shown in Figure 2(B), the fuel cell 104 of this embodiment is (a) The cell stack 104S which is the battery body, (b) A heat exchange section 104G in the cell stack 104S for transferring heat generated by the fuel cell reaction to the outside using a heat exchange medium, (c) A pressure vessel 104C that houses the cell stack 104S and the heat exchange section 104G inside a container filled with a filling gas such as air under high pressure (in this embodiment, filled with high-pressure gas from the high-pressure gas supply U101), (d) A pressure gauge 104Pa for monitoring the pressure of the filling gas in the pressure vessel 104C, (e) Based on the monitoring value of the gas pressure inside the pressure vessel 104C by the pressure gauge 104Pa, the internal pressure regulator 104P replenishes the amount of filling gas that has leaked out of the pressure vessel 104C (or exchanges filling gas with the pressure vessel 104C) and maintains the gas pressure inside the pressure vessel 104C at a "predetermined pressure value". It is equipped with.

[0125] Here, the cell stack 104S in (a) above is a battery body in which multiple cells are stacked (layered) together, each cell having a structure in which an oxidizing gas chamber on the air electrode side and a fuel gas chamber on the hydrogen electrode side are sandwiched between an electrolyte layer. Furthermore, the container pressure regulator 104P in (e) above includes a gas regulator (which can be adjusted according to the gas pressure monitoring value) and directly receives high-pressure air as the filling gas from the high-pressure gas supply U101 and supplies the received high-pressure air to the pressure vessel 104C while adjusting it with the gas regulator in order to set the gas pressure inside the pressure vessel 104C to a "predetermined pressure value". Here, it is also preferable that this "predetermined pressure value" (in (e) above) be set to a value equivalent to or slightly higher than the pressure (introduction pressure) of the high-pressure gas (high-pressure air or high-pressure hydrogen gas) introduced into the cell stack 104S. In this respect, in this embodiment, since the high-pressure air from the high-pressure gas supply U101 itself is used as the filling gas, such pressure setting is easy. Furthermore, as a modification, it is also possible to omit the internal pressure regulator 104P and pressure gauge 104Pa, and supply high-pressure air directly from the high-pressure gas supply U101 into the pressure vessel 104C.

[0126] In any case, in the fuel cell 104 described above, the cell stack 104S, which contains high-pressure gas at, for example, 9 atmospheres (approximately 0.9 MPa), receives a compressive force of, for example, about 9 atmospheres from the filling gas in the pressure vessel 104C. As a result, the fuel cell 104 can maintain a stable high-pressure state inside without being damaged or destroyed by the high-pressure gas inside, and can continuously carry out the high-pressure fuel cell reaction.

[0127] Furthermore, a portion of the high-pressure air (from the water exchange dehumidifier U105) introduced into the oxidation gas chamber of the fuel cell 104 may be used as the filling gas. Alternatively, instead of the high-pressure air from the high-pressure gas supply U101, compressed air from a compressed air supply system or compressed nitrogen gas from a nitrogen gas tank or compressed nitrogen gas supply system may be used as the filling gas. In addition, the internal pressure regulator 104P may be equipped with a cylinder or buffer tank with pressure and flow rate control functions containing the filling gas supplied to (or exchanged with) the pressure vessel 104C, and a pump for supplying the filling gas. Moreover, of course, the high-pressure fuel cell 104 is not limited to those described above. For example, the cell stack 104S itself may be made pressure-resistant to handle high introduction pressures without using a pressure vessel 104C. Furthermore, as mentioned above, in order to prevent damage to the electrolyte layer 104E of the fuel cell 104, it is preferable that the introduction pressure (back pressure) of the oxidizing gas chamber and the introduction pressure (back pressure) of the fuel gas chamber be set to be equivalent, for example, with an error of less than 0.1 atmospheres (approximately 0.01 MPa).

[0128] [Other embodiments of nitrogen filtering U109] Figure 3 is a schematic diagram showing another embodiment of the filtering means according to the present invention.

[0129] As described above, the nitrogen gas filter 109F in the nitrogen filter U109 of the embodiment shown in Figure 3 comprises a hollow fiber section 109Fa, a filter inlet section 109Fb for introducing high-pressure exhaust gas into the hollow fiber section 109Fa, a filter outlet section 109Fc for extracting (in this embodiment) high-purity nitrogen gas from the hollow fiber section 109Fa, and a filter purge section 109Fd for extracting filter exhaust gas containing oxygen gas separated by the hollow fiber section 109F separately from the high-purity nitrogen gas.

[0130] The filter exhaust gas extracted from the filter purging section 109Fd contains a considerable amount of separated oxygen gas, making it a gas that can be reused in the fuel cell reaction or subjected to further nitrogen filtering.

[0131] Incidentally, when using the UBE N2 separator NM-B01A manufactured by Ube Industries as the nitrogen gas filter 109F, and introducing a gas with an oxygen concentration of 10.2 vol% into this nitrogen gas filter 109F under the conditions of an introduction pressure of 6.0 atmospheres (approximately 0.61 MPa) and an outlet flow rate of 1.0 L / min, the oxygen concentration of the filter exhaust gas discharged from it was 14.9 vol%, which is considerably high, and furthermore, the recovery rate (= outlet flow rate / introduction flow rate) was 0.29. Incidentally, experiments have confirmed that the oxygen concentration of the filter exhaust gas increases as the introduction oxygen concentration increases, as the introduction pressure decreases, and as the outlet flow rate increases.

[0132] Therefore, in this embodiment, the nitrogen filter U109 uses the filter exhaust gas discharged from the nitrogen gas filter 109F to (a) The gas is sent back to the flow controller FCa (Figure 1) located upstream of the fuel cell U103, and used again as an oxidizing gas in the fuel cell 104 as a gas containing oxygen and nitrogen. (b) The gas is sent back to the off-gas buffer tank of the pressure adjustment unit PCb (Figure 1) located upstream of itself (in this embodiment, upstream of the dry filtering U107), and the mixed gas of the filtered exhaust gas and the high-pressure exhaust gas is subjected to nitrogen filtering treatment again by itself. This allows for the extraction of nitrogen gas with a lower oxygen concentration. However, it should be noted that if the oxygen concentration of the filtered exhaust gas is the same as or higher than that of air (20.8 vol%), the above benefits of returning the filtered exhaust gas to the air electrode side of the fuel cell 104 will not be realized.

[0133] Furthermore, as shown in Figure 3, the nitrogen filter U109 of this embodiment is provided with three nitrogen gas filters 109F1, 109F2, and 109F3 connected in parallel. Of course, the number of nitrogen gas filters connected in parallel is not limited to three; it may be two or four or more.

[0134] Specifically, the high-pressure exhaust gas supplied to the nitrogen filter U109 is divided and taken into three nitrogen gas filters 109F1, 109F2, and 109F3, respectively. Each nitrogen gas filter acts on the portion of the supplied high-pressure exhaust gas that it takes into itself to produce gas with increased nitrogen concentration, i.e., high-purity nitrogen gas. Finally, these high-purity nitrogen gases merge and are discharged from the nitrogen filter U109.

[0135] Furthermore, it is preferable that the filter exhaust gas discharged from each of the three nitrogen gas filters 109F1, 109F2, and 109F3 is sent back to the flow controller FCa (Figure 1) upstream of the fuel cell U103, as described above, and used again as an oxidizing gas in the fuel cell 104 as a gas containing oxygen and nitrogen, or sent back to the off-gas buffer tank of the pressure adjustment unit PCb (Figure 1), mixed with the high-pressure exhaust gas, and subjected to further (dry filtering and) nitrogen filtering.

[0136] As explained above, by arranging multiple nitrogen gas filters in parallel and performing nitrogen filtering, it becomes possible to simultaneously take in a large amount of high-pressure exhaust gas and provide a larger amount of high-purity nitrogen gas to the outside. For example, according to its catalog specifications, a 4-inch diameter nitrogen gas filter manufactured by Daicel-Evonik is said to discharge high-purity nitrogen gas with an oxygen concentration of approximately 0.1 vol% (assuming a recovery rate of approximately 0.25) at a flow rate of approximately 10 L / min when receiving air at 8 atmospheres (approximately 0.8 MPa) at a flow rate of 40 L / min.

[0137] If, for example, three such nitrogen gas filters are arranged in parallel, and exhaust gas (with a lower oxygen concentration than air, for example, 5-10 vol%) is fed into each nitrogen gas filter at 8 atmospheres (approximately 0.8 MPa) and a flow rate of 40 L / min, it becomes possible to supply high-purity nitrogen gas with an oxygen concentration of around 0.01 vol% (100 ppm vol), or significantly lower than 0.1 vol% (1000 ppm vol), for example, on the order of 100 ppm vol, to the outside at a total flow rate of approximately 30 (=10 × 3) L / min. Here, since the exhaust gas flows into each nitrogen gas filter at one-third of the original total flow rate of 120 (=40 × 3) L / min, the oxygen separation capacity of each nitrogen gas filter is improved compared to using a single nitrogen gas filter. Of course, if a larger diameter nitrogen gas filter, for example a 6-inch diameter filter, is used, it will be possible to supply an even larger amount of high-purity nitrogen gas.

[0138] [Catalytic combustion U108] Figure 4 is a schematic diagram showing another embodiment of the nitrogen gas generating apparatus / system according to the present invention.

[0139] The nitrogen gas generator (system) 1 of this embodiment shown in Figure 4 is characterized in that, compared to the embodiment shown in Figure 1, a catalytic combustion U108 is provided at a position downstream of the dry filtering U107 and upstream of the nitrogen filtering U109. This catalytic combustion U108 is (a) Exhaust gas with reduced moisture or water vapor content at high pressure (e.g., 3-10 atmospheres) before being taken into the nitrogen filter U109, (b) Hydrogen gas produced in gas reforming U121, for example, high-pressure (e.g., 3-10 atmospheres) hydrogen gas taken from downstream of hydrogen mixer Ma This is a means of bringing the material into contact with the combustion catalyst, specifically on the surface of the solid catalyst 108C in this embodiment, to induce a catalytic combustion reaction, thereby further reducing the oxygen concentration in the high-pressure exhaust gas described in (a) above.

[0140] Thus, in the catalytic combustion U108 of this embodiment, high-pressure (e.g., 3 to 10 atmospheres) gases come into contact with each other on the combustion catalyst, increasing the reaction rate of the catalytic combustion reaction and further promoting the reaction, thereby improving the effect of reducing the oxygen concentration in the high-pressure exhaust gas. Furthermore, as described in (b) above, the high-pressure hydrogen gas that comes into contact with the high-pressure exhaust gas does not need to be procured from outside the device (system) 1.

[0141] Furthermore, the solid catalyst 108C, which is the combustion catalyst in this embodiment, may be a ceramic honeycomb with numerous fine holes, on which metals such as platinum (Pt), palladium (Pd), or nickel (Ni) are supported as catalysts on the surface, including the inside of these holes. In addition, as such a solid catalyst 108C, for example, an NA honeycomb oxidation catalyst (platinum catalyst) manufactured by Nagamine Seisakusho Co., Ltd. can be used.

[0142] 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 support mainly composed of calcium aluminate (CaO·Al2O3), fused silica (SiO2), and titanium dioxide (TiO2). Here, the support has a honeycomb shape, and the contact area of ​​the platinum group metals supported on it is very large, so oxidation reactions are efficiently initiated.

[0143] Furthermore, the catalytic combustion reaction in such a solid catalyst 108C is accelerated as the temperature of the solid catalyst 108C increases. Therefore, it is important to heat the solid catalyst 108C to a predetermined required temperature, which can be done, for example, by wrapping a heating wire around the solid catalyst 108C and passing an electric current through it. In another preferred embodiment, induction heating may be performed on the solid catalyst 108C. Specifically, an iron-based alloy such as iron (Fe) or stainless steel is mixed into the support of the solid catalyst 108C, and a magnetic field (electromagnetic field) of, for example, several tens of kilohertz (kHz) to several hundred kHz is applied to such a solid catalyst 108C using an electromagnetic field generator, and the solid catalyst 108C is directly heated by Joule heating due to eddy currents generated by the principle of electromagnetic induction.

[0144] Here, in accordance with the skin effect of electromagnetic induction, it is also preferable to disperse iron powder, iron flakes, or iron-based alloys such as powdered or flaked stainless steel near the surface of the solid catalyst 108C support, for example, in the interior of the support to a depth of at least the penetration depth δ. This makes it possible to raise the portion of the solid catalyst 108C near the surface that needs to be heated to a predetermined high temperature with a uniform temperature distribution.

[0145] Alternatively, a plate made of iron or an iron-based alloy such as stainless steel can be placed in contact with, for example, the side of the solid catalyst 108C, and the solid catalyst 108C can be induced and heated through the plate by electromagnetic induction. In any case, when inductive heating of the solid catalyst 108C, even when using multiple solid catalysts 108Ca, wiring such as heating wires to each solid catalyst 108C is not required, and multiple solid catalysts 108C can be heated simultaneously and easily. It is also preferable that at least a portion of the power required for heating by electric heating or electromagnetic induction as described above be supplied from the fuel cell 104.

[0146] Furthermore, it is also preferable to use heat from the fuel cell 104 to heat the solid catalyst 108C as described above. Specifically, heat from the fuel cell 104 may be transferred to the solid catalyst 108C of the catalytic combustion U108 using heat transfer means such as a heat exchanger or a heat conduction system, and at least this heat may be used to heat the solid catalyst 108C necessary for catalytic combustion.

[0147] For example, it is possible to directly transfer heat by connecting the ends of a heat exchanger or heat conduction system to the solid catalyst 108C. Alternatively, the heat transferred by the heat exchanger or heat conduction system may be used to heat the gas reacting on the solid catalyst 108C. Of course, such heating using heat from the fuel cell 104 may be carried out in parallel with the heating by electric heating or electromagnetic induction described above. In any case, by utilizing the heat from the fuel cell 104, it is possible to reduce or nearly eliminate the power consumption in catalytic combustion U108.

[0148] Incidentally, in this embodiment, the oxygen concentration of the high-pressure exhaust gas used for catalytic combustion is, for example, about 0.5 to 10 vol%, and the reaction heat of catalytic combustion is considerably large, so in many cases, the solid catalyst 108C does not need to be heated to a high temperature, such as over 200°C. Therefore, depending on the specifications of the high-purity nitrogen gas that is ultimately provided, it is possible to cover most of the high temperature with heat from the fuel cell 104.

[0149] Furthermore, the catalytic combustion reaction in catalytic combustion U108 is also affected by the water vapor (H2O) content in the high-pressure exhaust gas. Therefore, there is a suitable water vapor content range for the introduced high-pressure exhaust gas that increases the catalytic combustion reaction rate. (a) The temperature controller TCa adjusts the temperature of the high-pressure exhaust gas taken into the water exchange dehumidifier U105, and controls the relative humidity (water vapor content) of the high-pressure exhaust gas taken out from the water exchange dehumidifier U105 to a value within a predetermined range, (b) The pressure controller PCa adjusts the pressure of the high-pressure exhaust gas taken into the dry filter U107 (the dry filter 107F), and controls the relative humidity (water vapor content) of the high-pressure exhaust gas taken out from the dry filter U107 to a value within a predetermined range. It is also preferable to introduce high-pressure exhaust gas within a suitable water vapor content range into the catalytic combustion U108.

[0150] Incidentally, regarding the installation position of the catalytic combustion U108, if the high-pressure exhaust gas extracted from the water exchange dehumidification U105 is within the above-mentioned preferred water vapor content range, it is also possible to install the catalytic combustion U108 before the dry filtering U107. In connection with this, as mentioned above, in the embodiment in which the dry filtering U107 is omitted, the high-pressure exhaust gas extracted from the water exchange dehumidification U105 and taken into the catalytic combustion U108 must be within the above-mentioned preferred water vapor content range or within the permissible water vapor content range.

[0151] Furthermore, the low-oxygen exhaust gas discharged from catalytic combustion U108 typically contains residual hydrogen gas that was not burned in the catalytic combustion reaction. Therefore, it is possible to install a hydrogen gas filter (not shown) immediately after catalytic combustion U108 to separate the residual hydrogen gas from this low-oxygen exhaust gas that has passed through catalytic combustion U108, and output exhaust gas with a further reduced or nearly zero hydrogen concentration. Incidentally, as this hydrogen gas filter, for example, a filter equipped with a palladium (Pd)-based hydrogen permeable membrane or a filter equipped with an aromatic polyimide-based hydrogen gas separation membrane may be used.

[0152] However, in this embodiment, the exhaust gas discharged from the catalytic combustion U108 is subsequently subjected to a nitrogen filtering process in the nitrogen filtering U109, which filters not only oxygen gas but also hydrogen gas as described above. Therefore, the hydrogen gas filter is basically unnecessary, although this depends on the specifications required for the high-purity nitrogen gas to be provided.

[0153] Furthermore, while this is a typical specification for the high-purity nitrogen gas output from the catalytic combustion U108 described above, if, for example, the catalytic combustion U108 receives high-pressure exhaust gas with an oxygen concentration of, for example, about 0.5 to 10 vol% from the dry filtering U107, and then performs catalytic combustion treatment under high pressure (for example, 9 atmospheres), it becomes possible to produce high-purity nitrogen gas with an oxygen concentration of, for example, less than 1000 ppm vol (0.1 vol%) from the catalytic combustion U108. Therefore, depending on the required specifications for the high-purity nitrogen gas to be provided, it is also possible to omit the nitrogen filtering U109 and have the oxygen concentration reduction treatment handled by the catalytic combustion U108.

[0154] Here, as another embodiment regarding the installation location of the catalytic combustion U108, it is also possible to install the catalytic combustion U108 downstream of the nitrogen filtering U109. In this case as well, catalytic combustion treatment is applied to the high-pressure exhaust gas (with increased nitrogen concentration) after nitrogen filtering, making it possible to ultimately output, for example, very high-purity (extremely low oxygen concentration) nitrogen gas.

[0155] However, in this case, the exhaust gas after nitrogen filtering is already a gas with a low oxygen concentration (e.g., on the order of 100 ppm vol). As a result, it is necessary to supply hydrogen gas to this exhaust gas in an amount that uses up the trace amount of oxygen gas in the exhaust gas while minimizing residual gas, which requires very sophisticated control. In other words, in this case, since the nitrogen filtering process that filters out hydrogen gas is not performed afterward, residual hydrogen gas must be suppressed as much as possible, and the control of the hydrogen gas supply amount must be extremely sophisticated.

[0156] Furthermore, in this case, the amount of oxygen gas is very small compared to general catalytic combustion, so the reaction heat generated by catalytic combustion is extremely small. Therefore, in order to carry out effective catalytic combustion, it becomes necessary to heat the solid catalyst 109C to, for example, about 250°C, and as a result, the power consumption of the catalytic combustion U108 increases.

[0157] In contrast, the apparatus configuration in this embodiment shown in Figure 4, in which catalytic combustion U108 is provided before the nitrogen filtering U109, is understood to be an excellent configuration that eliminates or prevents the problems of heating the solid catalyst 108C (i.e., the power consumption problem of catalytic combustion U108) and the problems of reducing and removing residual hydrogen gas (or the problem of controlling hydrogen gas supply during catalytic combustion) described above.

[0158] Furthermore, the configuration of this apparatus, in which catalytic combustion U108 is provided before the nitrogen filter U109, is also highly suitable from the viewpoint of the filtering effect (oxygen concentration reduction index) of the nitrogen gas filter 109F. First, the oxygen concentration reduction index of the nitrogen gas filter 109F, as an indicator of the filtering effect, is given by the following formula (1) (Oxygen concentration reduction index)=c_out_O2(Air) / c_out_O2 This is defined as follows: In equation (1) above, c_out_O2(Air) is the outlet oxygen concentration when air is introduced into the nitrogen gas filter 109F, and c_out_O2 is the outlet oxygen concentration when the gas subject to effect (index) evaluation is introduced into the nitrogen gas filter 109F.

[0159] In this experiment, using a UBE N2 separator manufactured by Ube Industries as the nitrogen gas filter 109F, and under conditions of an inlet pressure of 8 atmospheres (approximately 0.8 MPa) and an outlet flow rate of 2 L / min, when a nitrogen-oxygen mixed gas with an oxygen concentration of 1000 ppm vol (0.1 vol%), equivalent to the exhaust gas after catalytic combustion treatment in catalytic combustion U108, was introduced to this nitrogen gas filter 109F, the oxygen concentration reduction index (filtering effect) was approximately 170. On the other hand, under the same conditions, when a nitrogen-oxygen mixed gas with an oxygen concentration of 5.1 vol%, equivalent to the exhaust gas immediately after discharge from fuel cell 104, was introduced, the oxygen concentration reduction index (filtering effect) was only approximately 6.

[0160] Thus, it is understood that by providing a catalytic combustion U108 before the nitrogen filter U109 and introducing the exhaust gas after catalytic combustion treatment to the nitrogen gas filter 109F, a filtering effect (oxygen concentration reduction index) is obtained that is orders of magnitude greater than when introducing exhaust gas that has not undergone catalytic combustion treatment (immediately after being discharged from the fuel cell 104). In other words, by providing a catalytic combustion U108 before the nitrogen filter U109 and significantly reducing the oxygen concentration introduced to the nitrogen gas filter 109F in advance, it becomes possible to perform more efficient nitrogen filtering treatment.

[0161] As described above, the high-pressure fuel cell 104, dry filter U107, catalytic combustion U108, and nitrogen filter U109 are a highly suitable combination for producing high-purity nitrogen gas because, by forming a high-pressure, continuous system with respect to pressure (gas pressure), they can efficiently remove moisture and water vapor generated while promoting the efficiency of the battery reaction, and further reduce the oxygen concentration in the exhaust gas. For example, a pressure controller PCa, a pressure adjustment unit PCb, or even a pressure controller PCe or pressure controller PCd located downstream of the catalytic combustion U108 may be used to control the exhaust gas pressure to be consistently maintained at 8 to 10 atmospheres (approximately 0.8 to 10 MPa).

[0162] Furthermore, the aforementioned temperature controller TCa, the temperature controller TCc located before the catalytic combustion U108, and the aforementioned temperature controller TCb are means of controlling the temperature of the high-pressure exhaust gas taken from the fuel cell 104, the temperature of the high-pressure exhaust gas before it is taken into the catalytic combustion U108, and the temperature of the high-pressure exhaust gas before it is taken into the nitrogen filtering U109 to a temperature above a "temperature threshold" (e.g., 60°C, 80°C, and 50°C) set based on the "lower limit temperature" required or determined in the water exchange dehumidification U105, catalytic combustion U108, and nitrogen filtering U109. In other words, these temperature controllers are means of adjusting the exhaust gas temperature in a consistent manner throughout the entire device (system) 1. For example, they may be adjusted to consistently maintain an exhaust gas temperature of 60 to 80°C.

[0163] Here, it is also preferable that the above-mentioned temperature controller TCc, like temperature controllers TCa and TCb, uses heat from the fuel cell 104 (heat transferred by heat transfer means such as a heat exchanger or heat conduction system) to control the temperature of the high-pressure exhaust gas to a temperature above the "temperature threshold".

[0164] [High-pressure water electrolysis U125] Figure 5 is a schematic diagram showing yet another embodiment of the nitrogen gas generating apparatus / system according to the present invention.

[0165] The nitrogen gas generator (system) 1 of this embodiment shown in Figure 5, in the embodiment shown in Figure 4 which includes catalytic combustion U108 as a component, employs high-pressure water electrolysis U125 and a pressure adjustment unit PCf as high-pressure hydrogen gas generation means, instead of gas reforming U121 (Figure 4) and pressure boosting U123 (Figure 4). This high-pressure water electrolysis U125 is a high-pressure hydrogen generation means that electrolyzes a decomposition target which is water or water vapor supplied in a limited space (electrolytic cell), or a decomposition target which contains water or water vapor (the former in this embodiment), to generate high-pressure hydrogen gas having a pressure of a set "pressure threshold" or higher.

[0166] Specifically, the high-pressure water electrolysis U125 of this embodiment includes a "high-pressure water electrolyzer" 125E, which has a structure in which an ion exchange membrane 125Ec such as a solid polymer membrane is sandwiched between catalysts and electrodes (cathode 125Ea and anode 125Eb) on both sides, and is stacked in a plurality of these electrolytic cells. Of course, as long as it can generate high-pressure hydrogen gas, various other configurations and methods can be used for this "high-pressure water electrolyzer" 125E.

[0167] Here, the "pressure threshold" is set to the same value as the "pressure threshold" set for the high-pressure air generated by the high-pressure gas supply U101, as described above. In other words, the high-pressure water electrolysis U125 generates high-pressure hydrogen gas at a sufficiently high pressure so that the generated hydrogen gas can ultimately be introduced into the fuel cell 104 at a pressure approximately the same as that of the high-pressure air. In this embodiment, the high-pressure water electrolysis U125 can also generate high-pressure hydrogen gas at, for example, several hundred atmospheres. In this case, the generated high-pressure hydrogen gas is reduced to approximately the same pressure as the high-pressure air (for example, 3 to 10 atmospheres) in a pressure adjustment unit PCf equipped with a downstream buffer tank and a pressure adjustment valve.

[0168] Furthermore, the high-pressure water electrolyzer 125E of this embodiment generates high-temperature water or steam and electrolyzes it to produce high-pressure hydrogen gas in order to improve electrolysis efficiency (hydrogen generation efficiency). Here, it is also preferable that the high-pressure water electrolyzer 125E receives heat transferred from the fuel cell U103 by heat transfer means such as a heat exchanger or heat conduction system, and uses at least this heat to generate high-temperature water or steam, or to raise the temperature inside the electrolytic cell to increase the pressure of the hydrogen gas.

[0169] Furthermore, it is preferable that the high-pressure water electrolyzer 125E receives electricity generated by the fuel cell 104 and uses this electricity, or this electricity and commercial electricity, to perform electrolysis or generate high-temperature water or steam (for example, by electric heating). It is also preferable that water (pure water) taken out from the drains Da and Db of the fuel cell U103 and the dry filter 107F of the dry filtering U107 is received from a water collection and distribution pipe as a water supply means, and this water is also used as a raw material for electrolysis. In this way, by having the high-pressure water electrolyzer 125E receive and utilize heat, electricity and water from components within the device (system) 1 such as the fuel cell 104, it is possible to significantly reduce the amount of heat, electricity and water that needs to be supplied from outside the device (system) 1 for the electrolysis process.

[0170] In this embodiment, it is also preferable that a portion of the high-pressure hydrogen gas generated in the high-pressure water electrolyzer 125E is taken out, for example, from the downstream of the hydrogen mixer Ma and sent to the catalytic combustion U108. The catalytic combustion U108 uses this received high-pressure hydrogen gas as fuel gas for catalytic combustion. This makes it possible for the catalytic combustion U108 to perform catalytic combustion without introducing fuel gas from, for example, outside the apparatus (system) 1.

[0171] Incidentally, in the high-pressure water electrolysis unit 125E, it is also preferable that the high-pressure oxygen gas generated together with the high-pressure hydrogen gas be stored in an oxygen tank, for example, or supplied to the outside via predetermined piping.

[0172] As explained above, by combining the high-pressure water electrolysis U125 and the high-pressure compatible fuel cell 104 into a single high-pressure system, it is possible to generate high-pressure fuel gas (fuel gas) corresponding to the high-pressure air generated by the high-pressure gas supply U101 and use it in the fuel cell reaction while maintaining the high pressure, thereby supporting and promoting the generation of high-pressure exhaust gas, which is the source of high-purity nitrogen gas. In other words, the two are a very suitable combination for generating high-purity nitrogen gas. Incidentally, even in embodiments using a "normal gas pressure type" fuel cell 104, the high-pressure water electrolysis U125 described above can be employed, and the generated high-pressure hydrogen gas can be reduced in pressure and used as fuel gas. Alternatively, in this embodiment, hydrogen gas as fuel gas may be generated using a non-high-pressure type water electrolysis means.

[0173] The high-pressure water electrolysis U125 has been described above, but in order to secure a variety of hydrogen sources, the nitrogen gas generator (system) 1 may also be equipped with a gas reformer U121 (and a pressure booster U123) along with the high-pressure water electrolysis U125 as a means of generating high-pressure hydrogen. Alternatively, it is also possible to obtain high-pressure hydrogen gas itself from another system or device instead of or in conjunction with these means of generating high-pressure hydrogen. Below, we will describe the "natural energy power generation U127," which is preferable to be provided together with the "high-pressure water electrolysis U125," which can easily generate high-pressure hydrogen.

[0174] Similarly, in Figure 5, the renewable energy power generation U127 may be a solar power generation unit equipped with solar cells that convert sunlight into electricity, a wind power generation unit that generates electricity by rotating a rotor with blades using wind power to drive a generator, or a micro-hydropower generation unit that generates electricity by rotating a turbine using water flow (hydraulic power) to drive a generator.

[0175] Furthermore, any other type of power generation unit that ultimately converts the light energy of sunlight or the kinetic energy of wind and water flow into electrical energy can be adopted as the natural energy power generation unit 127. In addition, the natural energy power generation unit 127 may be a combination of two or more of the power generation units described above.

[0176] Furthermore, the renewable energy power generation unit 127 of this embodiment is equipped with a storage battery 127B, which is a secondary battery such as a lithium (Li) battery or a lead (Pb) battery, and stores the power it generates in the storage battery 127B (after converting AC power to DC power using a converter).

[0177] In this embodiment, the natural energy power generation unit 127 is equipped with a power generation meter to measure its own power generation and a storage meter to measure the amount of energy stored in the storage battery 127B, making it possible to measure the amount of power generated and stored at each point in time. In this embodiment, the overall control unit U131 checks the measured amount of power generated and stored, and then supplies power from the storage battery 127B to the high-pressure water electrolysis unit U125, which requires power for electrolysis, and to the high-pressure gas supply unit U101, which requires power for high-pressure air generation. Of course, commercial power may also be supplied here (to supplement any shortfall).

[0178] In any case, the combination of the renewable energy power generation unit 127, high-pressure water electrolysis U125, fuel cell U103, and catalytic combustion U108 described above generates hydrogen gas while minimizing the emission of greenhouse gases such as carbon dioxide (CO2) when producing high-purity nitrogen gas. In other words, it greatly contributes to the realization of a carbon-neutral or carbon-zero society.

[0179] [High-pressure gas supply U102: Gas pressure motor and gas compression pump] Figure 6 is a schematic diagram showing another embodiment of the high-pressure gas supply means according to the present invention.

[0180] The high-pressure gas supply U102 in this embodiment shown in Figure 6 is a high-pressure air generation means that was adopted in place of the high-pressure gas supply U101 (Figure 5) in the embodiment shown in Figure 5, which includes high-pressure water electrolysis U125 as a component.

[0181] Specifically in this embodiment, the high-pressure gas supply U102 is (M1) A gas pressure motor 102M1 as a gas pressure drive means that generates driving force using high-pressure oxygen gas produced by high-pressure water electrolysis U125, (P1) A compression pump 102P1, which is a gas compression means that converts the intake air (gas containing nitrogen and oxygen) into high-pressure air (gas containing nitrogen and oxygen at high pressure) by the driving force (rotational force in this embodiment) received from the gas pressure motor 102M1, (M2) A gas pressure motor 102M2 as a gas pressure drive means that generates driving force using high-pressure hydrogen gas produced by high-pressure water electrolysis U125, (P2) The compression pump 102P2, which is a gas compression means that converts the intake air (gas containing nitrogen and oxygen) into high-pressure air (gas containing nitrogen and oxygen at high pressure) by the driving force (rotational force in this embodiment) received from the gas pressure motor 102M2, It is equipped with.

[0182] Incidentally, the high-pressure water electrolysis U125 of this embodiment is capable of generating high-pressure hydrogen gas at tens to hundreds of atmospheres, and simultaneously generating high-pressure oxygen gas at tens to hundreds of atmospheres. This high-pressure oxygen gas is first buffered in oxygen tank TA1, and after its pressure and flow rate are adjusted by a pressure / flow controller provided at the tank outlet, it is introduced to the gas pressure motor 102M1. On the other hand, the high-pressure hydrogen gas is first buffered in hydrogen tank TA2, and after its pressure and flow rate are adjusted by a pressure / flow controller provided at the tank outlet, it is introduced to the gas pressure motor 102M2.

[0183] Here, since the configurations of (M1) and (P1) and (M2) and (P2) are similar in their mechanisms and operating modes, only the configurations of (M1) and (P1) will be described below. Note that the high-pressure gas supply U102 may have only the configurations of (M1) and (P1), or only the configurations of (M2) and (P2).

[0184] First, the gas pressure motor 102M1 is equipped with an eccentric rotor having multiple vanes (wing-shaped shutters) inside its main body casing. High-pressure oxygen gas supplied from the oxygen tank TA1 flows from the intake port into the space between the main body casing and the eccentric rotor, which is separated by adjacent vanes. The incoming high-pressure oxygen gas expands, exerting stronger pressure on one of the vanes, which in turn causes the eccentric rotor to rotate at high speed. As the eccentric rotor rotates, the expanded high-pressure air in this space weakens the total pressure on the vanes and is discharged from the main exhaust port and residual exhaust port, so the high-speed rotation of the eccentric rotor is maintained by the continuous inflow of high-pressure oxygen gas.

[0185] Next, the rotational force of the eccentric rotor is transmitted to the compression pump 102P1 via the eccentric rotor's shaft and an intermediate reduction gear mechanism. The compression pump 102P1 uses the received rotational force to compress, for example, air taken in from the outside, to generate high-pressure air. The high-pressure air generated here is adjusted to a predetermined pressure (for example, 3 to 10 atmospheres) by the pressure controller PCg and the flow controller FCa, and then supplied to the water exchange dehumidifier U105.

[0186] Incidentally, the compression pump 102P1 can be a known compressor that uses rotational force. Alternatively, as a modification, a gas-pressure linear actuator can be used as the gas-pressure drive means instead of the gas-pressure motor 102M1, and the driving force related to the reciprocating motion by high-pressure oxygen gas can be transmitted to the compression pump 102P1. In this case, the compression pump 102P1 can be a known compressor that uses the driving force related to this reciprocating motion.

[0187] In this embodiment, the pressure of the compressed air generated by the compression pump 102P1 (compression pump 102P2) is adjusted and set to a desired value by the overall control unit U131 (Figure 5), which monitors the pressure with a pressure controller PCg (pressure controller PCh), and controls the pressure and flow rate of the high-pressure oxygen gas (high-pressure hydrogen gas) introduced from the oxygen tank TA1 (hydrogen tank TA2) to the gas pressure motor 102M1 (gas pressure motor 102M2).

[0188] Furthermore, it is preferable that the high-pressure oxygen gas discharged from the main exhaust port and residual exhaust port of the gas pressure motor 102M1 be recovered and stored in an oxygen tank, for example, or provided to the outside via predetermined piping. In addition, although this applies to the configurations of (M2) and (P2) described above, the high-pressure hydrogen gas discharged from the main exhaust port and residual exhaust port of the gas pressure motor 102M2 is adjusted to a predetermined flow rate and pressure (for example, 3 to 10 atmospheres) by the flow controller FCb and supplied to the fuel cell U103 as fuel gas.

[0189] As explained above, the high-pressure gas supply U102 generates high-pressure air by utilizing the physical energy of the high-pressure gas supplied from the high-pressure water electrolysis U125. Therefore, unlike a typical compressor (using an electric motor) that consumes a considerable amount of power, the power consumption during high-pressure air generation can be reduced to almost zero. As a result, it becomes possible to provide more of the electricity generated by the fuel cell U103 to external parties instead of using it for high-pressure air generation.

[0190] [Other embodiments of the fuel cell U103] Figure 7 is a schematic diagram illustrating another embodiment of the fuel cell U according to the present invention.

[0191] The fuel cell U103 of this embodiment, shown in Figure 7, comprises a fuel cell 104 and control units 103Ca, 103Cb, and 103Cc. The fuel cell 104 comprises multiple cells, which are constituent units including a hydrogen electrode and an air electrode with an electrolyte layer in between. These cells are stacked, and are designed so that hydrogen (fuel gas) and air (gas containing nitrogen and oxygen) pass through the hydrogen electrode and air electrode within each cell sequentially, from the cell on the upper side to the cell on the lower side.

[0192] Furthermore, the entirety of these multiple cells is divided into multiple functional cell sections, in Figure 7, a power generation priority cell section 104a, an intermediate cell section 103b, and an oxygen removal cell section 103. Each of these functional cell sections (104a, 104b, 104c) contains one or a series of cells (two or three in Figure 7, actually several to several hundred), and is not electrically connected in series with the other functional cell sections, but is electrically connected to a power generation control unit (103Ca, 103Cb, 103Cc) that is provided individually for each.

[0193] As shown in Figure 7, the control units 103Ca, 103Cb, and 103Cc receive the electromotive force generated between the hydrogen electrode and air electrode in the power generation priority cell section 104a, the intermediate cell section 104b, and the oxygen removal cell section 104c, respectively, and output power corresponding to the functional cell section they are responsible for. It is also preferable to measure the complex impedance of the functional cell section in charge and perform control and management according to that functional cell section.

[0194] In contrast to the fuel cell 104 of this embodiment, conventional fuel cells, especially PEFC type fuel cells, typically have an electromotive force of less than 1V (volt) in a single cell. Therefore, in order to secure the power required as an actual power source, a series of several hundred cells are electrically connected in series. In this configuration, the amount of power that can be generated is naturally smaller in the lower-level cells with less oxygen supply. However, the power generation efficiency (relative to the amount of hydrogen supplied) of the entire series of cells, including these lower-level cells, is considerably impaired because the power generation of each cell must be somewhat equalized.

[0195] In contrast, in the fuel cell 104 of this embodiment, (a) A power generation priority cell section 104a with a large oxygen supply (where the oxygen in the supplied air has not yet been consumed much), (b) Intermediate cell section 104b with respect to oxygen supply, (c) The oxygen removal cell section 104c has a low oxygen supply (a considerable amount of oxygen in the supplied air is consumed) However, it can receive individual power generation control that is tailored to the oxygen supply level.

[0196] Furthermore, by implementing this power generation control, it becomes possible to maximize or improve both the oxygen reduction efficiency and the power generation efficiency (relative to the hydrogen supply) in the fuel cell 104. In addition, by simultaneously controlling the power generation in each control unit (103Ca, 103Cb, 103Cc), it becomes possible to adjust the oxygen concentration of the exhaust gas (outlet oxygen concentration) to a desired value.

[0197] Thus, the fuel cell 104 of this embodiment is a very suitable fuel cell for generating high-purity nitrogen gas. Of course, this fuel cell 104 may also be used for other general purposes as a suitable fuel cell that allows for optimization of power generation efficiency.

[0198] Incidentally, the number of functional cell sections in the fuel cell 104 of this embodiment is not limited to three, but can be two or four or more. For example, out of several hundred cell stages, the lower 150 cell stage group and the upper remaining cell stage group can be designated as the first functional cell section and the second functional cell section, respectively.

[0199] [Overall Control Unit 131] Here, we will explain the overall control unit 131 shown in Figures 1, 4, and 5. The following explanation will focus on the control of the overall control unit 131 shown in Figure 5, but the explanations regarding the components (units) present in Figures 1 and 4 also apply to the overall control unit 131 shown in Figures 1 and 4.

[0200] The overall control unit 131 shown in Figure 5 is (a) High-pressure air generation process in high-pressure gas supply U101, (b) High-pressure hydrogen generation process in high-pressure water electrolysis U125, (c) High-pressure exhaust gas generation process in fuel cell U103, (d) High-pressure exhaust gas dehumidification treatment in water exchange dehumidification U105, (e) High-pressure exhaust gas dehumidification treatment in dry filtering U107, (f) High-pressure exhaust gas deoxygenation treatment in catalytic combustion U108, and (g) High-purity nitrogen gas generation process in nitrogen filtering U109 This is a control means that controls and implements each of these.

[0201] Specifically, the overall control unit 131 of this embodiment is capable of communicating with each of the units (a) to (g) described above, and with various instruments and devices provided within or before / after those units, via a wired or wireless communication network. Based on measurement data from these instruments and devices, it transmits control and adjustment instructions to each of the units (a) to (g) described above and to the instruments and devices, thereby controlling and executing each of the processes described (a) to (g).

[0202] In this embodiment, the overall control unit 131 includes a processor and memory, and this memory stores and stores a processing control program for controlling each of the processes (a) to (g) described above, and this processing control program is executed by this processor. In a preferred embodiment, this processing control program may execute the control process using a machine learning model for processing control, such as a model constructed with a DNN (Deep Neural Network) algorithm, with measurement data from the various instruments and devices as explanatory variables and the control and adjustment instruction information as the objective variable.

[0203] Furthermore, it is also preferable that the overall control unit 131 of this embodiment treats the fuel cell 104, dry filtering U107, catalytic combustion U108, and nitrogen filtering U109 as a single high-pressure through-system with respect to pressure (gas pressure), and uses the above-mentioned processing control program to send pressure (flow rate) control and adjustment instructions to the pressure controller PCa, pressure adjustment unit PCb, pressure controller PCd, and flow controller FCc, etc., so that the pressure of the exhaust gas along the way remains consistently at, for example, 8 to 10 atmospheres (approximately 0.8 to 10 MPa).

[0204] Furthermore, the overall control unit 131 of this embodiment may also use the above-described processing control program to send temperature control and adjustment instructions to temperature controllers TCa, TCc, and TCb, etc., so that the temperature of the exhaust gas along the way remains consistently, for example, 60 to 80°C.

[0205] Furthermore, it is preferable that the overall control unit 131 monitors the oxygen concentration of the high-pressure exhaust gas (outlet) extracted from the fuel cell U103, catalytic combustion U108, and nitrogen filtering U109 (using an oxygen concentration meter installed at the relevant location), and controls the oxygen concentration of the high-purity nitrogen gas ultimately supplied to be below a predetermined upper limit determined by the required specifications.

[0206] In this case, specifically, the overall control unit 131 uses, for example, the same processing control program as described above, (a) In the case where the fuel cell U103 (fuel cell 104) is as shown in Figure 7, a power generation control / adjustment instruction is sent to each control unit (103Ca, 103Cb, 103Cc) corresponding to each functional cell unit (104a, 104b, 104c) to set the power generation amount to a predetermined value. (b) In order to control the reduction in oxygen concentration due to the catalytic combustion treatment in catalytic combustion U108, a catalyst temperature control / adjustment instruction is sent to catalytic combustion U108 to adjust the heating treatment (heating temperature) of the solid catalyst 108C, (c) In order to control the reduction in oxygen concentration due to nitrogen filtering in nitrogen filter U109, flow rate / pressure control / adjustment instructions are sent to the flow controller FCc to set the outlet flow rate and outlet pressure of nitrogen filter U109 to predetermined values. This allows for the control and adjustment of the oxygen concentration in the exhaust gas extracted from each unit.

[0207] As described in detail above, according to the present invention, by subjecting the exhaust gas from a fuel cell to water exchange dehumidification treatment and nitrogen filtering treatment, it is possible to reliably and stably produce high-purity nitrogen gas. Furthermore, in one embodiment, by using catalytic combustion treatment, it is possible to produce even higher-purity nitrogen gas more reliably, more stably, and more efficiently.

[0208] Furthermore, in the future, when a hydrogen gas society and a carbon-free society arrive, the use of fuel cells that utilize hydrogen gas as a fuel gas is expected to become widespread everywhere. This invention will greatly contribute to the efficient production of nitrogen gas in such an era. Of course, it will also be possible to meet the needs for supplying electricity, heat, and in some cases, pure water on the same site.

[0209] In other words, this invention is expected to contribute to the creation of a locally produced and consumed, carbon-free energy and product supply and demand system, which is considered an ideal model for the future. Furthermore, it is expected to be of great help in achieving carbon neutrality, which is an urgent issue.

[0210] Furthermore, although this is merely one embodiment of the present invention, it is also possible to supply hydrogen gas to the fuel cell as a fuel gas by using a high-pressure electrolysis means. Such a configuration is also expected to be widely utilized in the hydrogen gas society and carbon-free society described above.

[0211] Furthermore, all embodiments described above are illustrative and not limiting to the present invention, and the present invention can be implemented in various other variations and modifications. Accordingly, the scope of the present invention is defined solely by the claims and their equivalents. [Explanation of Symbols]

[0212] 1. Nitrogen gas generation equipment / system 101, 102 High-pressure gas supply unit (U) 102M1, 102M2 Gas Pressure Motor 102P1, 102P2 Compressor Pumps 103 Fuel Cell U 103Ca, 103Cb, 103Cc control unit 104 Fuel Cell 104C Pressure Vessel 104E Electrolyte layer 104G heat exchange section 104H Fuel Gas Chamber 104P Internal pressure regulator 104 Pa pressure gauge 104S Cell Stack 104X Oxidizing gas chamber 105 Water exchange dehumidification U 105D Dehumidification room 105H Humidification room 105V water vapor exchange membrane 107 Dry Filtering U 107F Dry Filter 108 Catalytic Combustion U 108C solid catalyst 109 Nitrogen Filtering U 109F, 109F1, 109F2, 109F3 Nitrogen Gas Filters 109Fa Hollow fiber section 109Fb filter inlet 109Fc filter outlet 109Fd Filter Purge Section 121 Gas Reforming U 123 Pressure Booster U 125 High-pressure water electrolysis U 125E High-Pressure Water Electrolyzer 125Ea cathode 125Eb Anode 125Ec Ion exchange membrane 127 Renewable Energy Power Generation U 127B storage battery 129 Hydrogen Recovery U 131 Overall control U

Claims

1. A fuel cell that operates by taking in air or a gas containing nitrogen and oxygen, and a fuel gas; a water exchange and dehumidification means for performing water exchange between exhaust gas having an oxygen concentration lower than that of air and the air or the gas containing nitrogen and oxygen introduced into the fuel cell, thereby reducing the moisture or water vapor content in the exhaust gas; a nitrogen filtering means for converting the exhaust gas having a reduced moisture or water vapor content into a gas having an increased nitrogen concentration, the nitrogen filtering means being provided with filters having different degrees of permeability for nitrogen and oxygen; A nitrogen gas generating device comprising:

2. The nitrogen gas generating device according to claim 1, further comprising a catalytic combustion means for reacting the exhaust gas, which has had its moisture or water vapor content reduced before being taken into the nitrogen filtering means, with the fuel gas on a combustion catalyst, or for reacting the gas, which has had its nitrogen concentration increased and which has been removed from the nitrogen filtering means, with the fuel gas on a combustion catalyst, thereby further reducing the oxygen concentration in the exhaust gas or the gas, which has had its nitrogen concentration increased.

3. The fuel cell further includes a high-pressure gas supply means for supplying high-pressure air or a gas containing high-pressure nitrogen and oxygen having a pressure equal to or higher than a pressure threshold value set based on at least a lower limit pressure required or determined by the nitrogen filtering means, The water exchange dehumidification means reduces the moisture or water vapor content in the high-pressure exhaust gas having a pressure equal to or higher than the pressure threshold value, The nitrogen filtering means converts the high-pressure exhaust gas into a gas having an increased nitrogen concentration with a reduced moisture or water vapor content.

3. The nitrogen gas generating device according to claim 1 or 2.

4. Further comprising a dry filtering means having a dry filter for further reducing the moisture or water vapor content in the high-pressure exhaust gas extracted from the water exchange dehumidification means, The pressure threshold is set based on a lower limit pressure required or determined in the dry filtering means.

4. The nitrogen gas generating device according to claim 3.

5. The apparatus further includes a high-pressure electrolysis means for electrolyzing a decomposition target that is water or water vapor or a decomposition target that contains water or water vapor supplied in a limited space, and generating high-pressure hydrogen gas having a pressure equal to or higher than the pressure threshold value; The fuel cell takes in the high-pressure hydrogen gas and the high-pressure air or the high-pressure gas containing nitrogen and oxygen, and discharges the high-pressure exhaust gas.

5. The nitrogen gas generating device according to claim 3 or 4.

6. 6. The nitrogen gas generating device according to claim 5, further comprising a heat transfer means for transferring heat from the fuel cell to the high-pressure electrolysis means and generating the high-pressure hydrogen gas using at least the heat.

7. a dry filtering means for further reducing the moisture or water vapor content in the high-pressure exhaust gas taken out from the water exchange dehumidification means; a water supply means for supplying water from the dry filtering means, or water from the dry filtering means and the fuel cell, to the high-pressure electrolysis means as the water to be decomposed; 7. The nitrogen gas generating apparatus according to claim 5 or 6, further comprising:

8. The system further comprises catalytic combustion means for reacting the high-pressure exhaust gas with reduced moisture or water vapor content before being introduced into the nitrogen filtering means with the fuel gas on a combustion catalyst, or for reacting the gas with increased nitrogen concentration taken out from the nitrogen filtering means with the fuel gas on a combustion catalyst, thereby further reducing the oxygen concentration in the high-pressure exhaust gas or the gas with increased nitrogen concentration, The catalytic combustion means uses at least the generated high-pressure hydrogen gas as the fuel gas used for catalytic combustion.

8. The nitrogen gas generating device according to claim 5, wherein the nitrogen gas generating device is a gas supply device.

9. The high pressure gas supply means includes: a gas pressure driving means for generating a driving force using the generated high-pressure hydrogen gas and / or the high-pressure oxygen gas having a pressure equal to or higher than the pressure threshold value generated by the high-pressure electrolysis means; a gas compression means for converting the air or the gas containing nitrogen and oxygen into the high-pressure air or the gas containing nitrogen and oxygen by the received driving force; 9. The nitrogen gas generating device according to claim 5, further comprising:

10. 9. The nitrogen gas generating device according to claim 2 or 8, further comprising a heat transfer means for transferring heat from the fuel cell to the catalytic combustion means and using at least the heat to heat the combustion catalyst required during catalytic combustion.

11. a pressure adjusting means for adjusting the exhaust gas taken out from the water exchange dehumidification means to a high-pressure exhaust gas having a pressure equal to or higher than a pressure threshold set based on at least a lower limit pressure required or determined in the nitrogen filtering means; a dry filtering means having a dry filter for further reducing the moisture or water vapor content in the high-pressure exhaust gas extracted from the pressure regulating means; 3. The nitrogen gas generating apparatus according to claim 1 or 2, further comprising:

12. 12. The nitrogen gas generating device according to claim 3, wherein the lower limit pressure is set to a pressure value of at least 3 atmospheres.

13. A nitrogen gas generating device as described in any one of claims 1 to 12, further comprising a temperature adjustment means for adjusting the temperature of the exhaust gas extracted from the fuel cell and / or the temperature of the exhaust gas before being taken into the nitrogen filtering means to a temperature equal to or higher than a temperature threshold set based on a lower limit temperature required or determined in the water exchange dehumidification means and / or the nitrogen filtering means.

14. 14. The nitrogen gas generating device according to claim 13, wherein the temperature adjusting means uses heat from a fuel cell to control the temperature of the exhaust gas to a temperature equal to or higher than the temperature threshold value.

15. The fuel cell comprises a plurality of cells, which are structural units each including two electrodes sandwiching an electrolyte therebetween, and the entirety of the plurality of cells is divided into a plurality of functional cell sections, each of which includes one or a plurality of consecutive cells, is not electrically connected in series with other functional cell sections, and is electrically connected to an individual power generation control unit. A nitrogen gas generating device as described in any one of claims 1 to 14, characterized in that the fuel cell comprises a plurality of cells, which are each divided into a plurality of functional cell sections each including one or a plurality of consecutive cells, is not electrically connected in series with other functional cell sections, and is electrically connected to an individual power generation control unit.

16. A fuel cell that operates by taking in air or a gas containing nitrogen and oxygen, and a fuel gas; a water exchange and dehumidification means for performing water exchange between exhaust gas having an oxygen concentration lower than that of air and the air or the gas containing nitrogen and oxygen introduced into the fuel cell, thereby reducing the moisture or water vapor content in the exhaust gas; a nitrogen filtering means for converting the exhaust gas having a reduced moisture or water vapor content into a gas having an increased nitrogen concentration, the nitrogen filtering means being provided with filters having different degrees of permeability for nitrogen and oxygen; A nitrogen gas generating system comprising:

17. supplying air or a gas containing nitrogen and oxygen and a fuel gas to the fuel cell to operate the fuel cell; performing water exchange between exhaust gas having an oxygen concentration lower than that of air and the air or the gas containing nitrogen and oxygen introduced into the fuel cell, thereby reducing the moisture or water vapor content in the exhaust gas; applying the exhaust gas with reduced moisture or water vapor content to a filter having different permeabilities for nitrogen and oxygen, and extracting the exhaust gas with increased nitrogen concentration from the filter; A method for generating nitrogen gas, comprising:

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