JP2021136084A - Method for producing nitrogen gas for filtering fuel battery exhaust gas and device - Google Patents

Abstract

To provide a method of effectively generating a nitrogen gas with high purity by using a fuel battery.SOLUTION: A method for producing nitrogen gas is characterized in that a gas containing air, nitrogen or oxygen, and a fuel gas are supplied to a fuel battery to operate the fuel battery; an exhaust gas having an oxygen concentration lower than that of the air is taken out of the fuel battery; the exhaust gas is made to act on a filter using fibers having different penetration level of nitrogen and oxygen to take out the exhaust gas where a nitrogen concentration is increased from this filter. Here, it is preferable that the air or the gas, having a pressure exceeding an atmospheric pressure and the fuel gas having a pressure exceeding the atmospheric pressure are supplied to the fuel battery, and the exhaust gas having the pressure exceeding the atmospheric pressure and the oxygen concentration lower than the air is taken out from this fuel battery, and the exhaust gas is made to act on the filter with the pressure exceeding the atmospheric pressure.SELECTED DRAWING: Figure 1

Description

The present invention relates to a technique for producing high-purity nitrogen gas.

In recent years, the use of fuel cells has been actively promoted. For example, fuel cell vehicles have been put into practical use, and household and industrial fuel cell equipment is becoming widespread. Using a fuel cell not only realizes high-efficiency power generation, but also makes it possible to reduce carbon dioxide emissions to almost zero, unlike conventional power generation means using an internal combustion engine. From this, fuel cell technology is expected to greatly contribute to the realization of a low-carbon society.

The inventors of the present application have paid attention to the potential of such a fuel cell, and have invented a soldering device using a fuel cell as described in Patent Documents 1 and 2. In this soldering device, not only the electric power generated by the fuel cell but also the exhaust gas generated by the power generation is supplied to the soldering device and used.

Furthermore, as described in Patent Documents 3 and 4, the inventors of the present application apply the inert gas and electric power to a processing apparatus for processing by heating the object to be heated with electric power in the inert gas. He has also invented a power generation device that uses a fuel cell to supply and. This power generation device can also remove or reduce oxygen, water vapor, and water contained in the exhaust gas from the fuel cell, and convert the exhaust gas into an inert gas suitable for use in the processing device. It is.

Japanese Unexamined Patent Publication No. 2013-233549 Japanese Unexamined Patent Publication No. 2016-164987 Japanese Unexamined Patent Publication No. 2017-084796 JP-A-2018-163890

Here, the inventors of the present application have come to the conclusion that if a fuel cell is also used, it is possible to supply high-purity nitrogen gas, which is in great demand at various production and service provision sites.

Such a high-purity nitrogen gas is an inert gas that is neither fuel-supporting nor flammable, and is a very useful gas. At present, it is produced by an air separation method, a membrane separation method, or the like.

Here, I thought that it would be possible to efficiently generate high-purity nitrogen gas by using the exhaust gas from fuel cells instead of using air as a raw material as in the past. .. Of course, since a fuel cell is used, electric power can be supplied in accordance with high-purity nitrogen gas.

Therefore, an object of the present invention is to provide a method and an apparatus for efficiently generating high-purity nitrogen gas using a fuel cell.

According to the present invention, air or a gas containing nitrogen and oxygen and a fuel gas are supplied to the fuel cell to operate the fuel cell.
Exhaust gas with an oxygen concentration lower than that of air is extracted from the fuel cell.
The exhaust gas is allowed to act on a filter using fibers having different degrees of permeation for nitrogen and oxygen (for example, hollow fiber fibers), and the exhaust gas having an increased nitrogen concentration is taken out from the filter. A gas production method is provided.

In the method for producing nitrogen gas according to the present invention, the air or the gas having a pressure exceeding the atmospheric pressure and the fuel gas having a pressure exceeding the atmospheric pressure are supplied to the fuel cell, and the fuel cell is subjected to a large amount. Take out the exhaust gas that has a pressure exceeding the pressure and has an oxygen concentration lower than that of the air.
It is also preferable that the exhaust gas acts on the filter at a pressure exceeding atmospheric pressure.

Further, as one embodiment of the nitrogen gas generation method according to the present invention, it is also preferable that the exhaust gas taken out from the fuel cell is further increased in pressure by using a pressure increasing means and then acted on the filter.

Further, in the nitrogen gas generation method according to the present invention, the pressure of the exhaust gas acting on the filter is a pressure threshold value determined by the filter, and is larger as the flow rate of the exhaust gas when taken out from the filter increases. It is also preferable that the pressure exceeds the pressure threshold value.

Further, in the nitrogen gas generation method according to the present invention, it is also preferable to use a filter as the filter on which the exhaust gas acts, the lower the oxygen concentration of the gas to be filtered, the higher the recovery rate.

Further, in the nitrogen gas generation method according to the present invention, an exhaust gas having an oxygen concentration of 2.5% by volume or less is allowed to act on the filter, and the oxygen concentration is higher than the result of applying air from this filter. It is also preferable to take out the exhaust gas which is 1/10 or less.

Further, as another embodiment of the nitrogen gas generation method according to the present invention, from a filter on which the exhaust gas is allowed to act, a filter exhaust gas containing a gas permeated through the fibers (specifically, nitrogen (in the exhaust gas) by the filter). A gas containing oxygen molecules separated from the molecules), and a filter exhaust gas different from the exhaust gas whose nitrogen concentration has increased is taken out.
It is also preferable to use the extracted filter exhaust gas as a part of the gas supplied to the fuel cell and / or to use it in addition to the exhaust gas acting on the filter.

Further, as a further other embodiment in the nitrogen gas generation method according to the present invention, the exhaust gas is a filter exhaust gas containing a gas permeated through the fibers from a filter on which the exhaust gas is allowed to act, and the exhaust gas has an increased nitrogen concentration. Take out another filter exhaust gas,
Using the above filter as the first filter, N filters from the first filter using the fiber that permeates more oxygen than nitrogen to the Nth filter (N is an integer of 2 or more). In such a process, from the nth filter (n is 1 or more and an integer up to (N-1)), the exhaust gas having an increased nitrogen concentration or the exhaust gas from the filter having an increased nitrogen concentration, and what is it? Another process of taking out the filter exhaust gas, causing the taken out filter exhaust gas to act on the (n + 1) th filter, and taking out the filter exhaust gas having an increased nitrogen concentration from the (n + 1) th filter. It is also preferable to carry out.

Further, as a further other embodiment in the nitrogen gas generation method according to the present invention, the above filter is used as the first filter, and the first filter using the fiber that permeates more oxygen than nitrogen is used. Processing related to N filters up to N (N is an integer of 2 or more), and nitrogen concentration from the nth filter (n is 1 or more and an integer up to (N-1)). It is also possible to take out the increased exhaust gas, cause the taken out exhaust gas to act on the (n + 1) th filter, and take out the exhaust gas having an increased nitrogen concentration from the (n + 1) th filter. preferable.

Further, in the method for producing nitrogen gas according to the present invention, a treatment for removing or reducing at least one of sulfide, chloride, hydrocarbon, fluoride and a strong alkaline compound is performed on the exhaust gas taken out from the fuel cell. It is also preferable to let the exhaust gas act on the filter after the application.

Further, in the nitrogen gas generation method according to the present invention, the temperature of the exhaust gas taken out from the fuel cell is the temperature of the exhaust gas taken out from the fuel cell by using a temperature adjusting means capable of bringing the temperature of the introduced gas close to a suitable temperature set based on the characteristics of the filter. It is also preferable to let the exhaust gas act on the filter after adjusting the above.

Further, as yet another embodiment of the method for producing nitrogen gas according to the present invention, the exhaust gas taken out from the filter is supplied into another fuel cell and contains oxygen that has undergone a fuel cell reaction. Then, the original fuel gas supplied into the battery is brought close to the fuel gas via an electrolyte and supplied to another fuel cell capable of causing a fuel cell reaction, and this other fuel cell is operated. It is also preferable to extract the exhaust gas having a lower oxygen concentration from another fuel cell.

Further, as a further other embodiment in the nitrogen gas generation method according to the present invention, the exhaust gas taken out from the filter and the fuel gas are reacted on a combustion catalyst, and the exhaust gas has a lower oxygen concentration. It is also preferable to use exhaust gas.

Further, as yet another embodiment in the method for producing nitrogen gas according to the present invention, the above fuel cell is initially supplied into the battery with the air or the gas that has been supplied into the battery and undergoes a fuel cell reaction. It is also preferable that the fuel cell is capable of causing a fuel cell reaction by bringing the fuel gas in the vicinity thereof via an electrolyte.

According to the present invention, the fuel cell and
Filters using fibers with different degrees of permeation for nitrogen and oxygen,
A pressure control means capable of supplying air having a pressure exceeding atmospheric pressure, a gas containing nitrogen and oxygen having a pressure exceeding atmospheric pressure, and a fuel gas having a pressure exceeding atmospheric pressure to the fuel cell.
Exhaust gas discharged from the operating fuel cell, which has a pressure exceeding atmospheric pressure and has an oxygen concentration lower than that of air, is introduced to act on the filter, and the exhaust gas having an increased nitrogen concentration from the filter is introduced. A nitrogen gas generator having a filter input / output unit for taking out the fuel gas is provided.

According to the present invention, it is possible to efficiently generate high-purity nitrogen gas by using a fuel cell.

It is a schematic diagram which shows one Embodiment of the nitrogen gas generation system by this invention. It is a graph for demonstrating Example 1 which concerns on the nitrogen gas generation processing by this invention. It is a graph for demonstrating Example 1 which concerns on the nitrogen gas generation processing by this invention. It is a graph for demonstrating Example 1 which concerns on the nitrogen gas generation processing by this invention. It is a graph for demonstrating Example 2 which investigated the recovery rate of the nitrogen gas filter in the nitrogen gas generation processing by this invention. It is a schematic diagram for demonstrating another embodiment about the nitrogen filter U which concerns on this invention. It is a graph which showed the relationship between the introduction oxygen concentration in the nitrogen gas filter which concerns on this invention, and the oxygen concentration of a filter exhaust gas. It is a schematic diagram for demonstrating another embodiment about the "fuel cell" which concerns on this invention. It is a schematic diagram for demonstrating further other embodiment about the "fuel cell" which concerns on this invention. It is a schematic diagram for demonstrating further other embodiment about the nitrogen gas generation system by this invention. It is a schematic diagram for demonstrating further other embodiment about the nitrogen gas generation system by this invention. It is a graph which shows the relationship between the current and the voltage in the "fuel cell" in one Example which investigated the driving state of the "fuel cell" which concerns on this invention. It is a graph which shows the relationship between the cell temperature and electric power in the "fuel cell" in one Example which investigated the driving state of the "fuel cell" which concerns on this invention. It is a graph which shows the relationship between the cell temperature of a "fuel cell" and the relative humidity of the exhaust gas in one Example which investigated the driving state of the "fuel cell" which concerns on this invention.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In each drawing, the same components are shown using the same reference numbers. Components that can have similar structures and functions may also be indicated with the same reference number. Further, the dimensional ratios within the components and between the components in the drawing are arbitrary for the sake of readability of the drawing.

[Nitrogen gas generation system / equipment]
FIG. 1 is a schematic view showing an embodiment of a nitrogen gas generation system according to the present invention.

The nitrogen gas generation system 1 as an embodiment of the present invention shown in FIG. 1 has a remarkable feature.
(A) "Air or a gas containing nitrogen and oxygen" and "fuel gas" (hydrogen in this embodiment) are supplied to the "fuel cell (in the fuel cell U11)", and this "fuel cell" To run,
(B) Extract "exhaust gas (off gas)" having an oxygen concentration lower than that of air from the "fuel cell".
(C) "Exhaust gas" is allowed to act on a "nitrogen gas filter 12f" using fibers having different degrees of permeation for nitrogen and oxygen (for example, hollow yarn fibers), and nitrogen is generated from this "nitrogen gas filter 12f". It is a system that can implement a characteristic nitrogen gas generation method such as extracting "exhaust gas" with an increased concentration.

Here, the "nitrogen gas filter 12f" of the above (C) is a filter using fibers having different degrees of permeation for nitrogen and oxygen as described above, and the inventors of the present application (later described the contents thereof). In the filter using the fiber, the "oxygen concentration reduction index" in the "exhaust gas" having an oxygen concentration lower than that of air (ml in 100 ml of the medium and the unit is volume (vol)%) is , It has been confirmed by experiments that the lower the oxygen concentration, the higher the increase.

As described above, according to the nitrogen gas generation system 1, the low oxygen concentration can be efficiently achieved by combining the "fuel cell" and the "nitrogen gas filter 12f", which are very compatible with each other from the viewpoint of the low oxygen concentration. That is, it is possible to generate high-purity nitrogen gas.

Incidentally, as will be described in detail later, the inventors of the present application have described the "nitrogen gas filter 12f" by allowing "exhaust gas" having an oxygen concentration of 2.5 vol% or less to act on the "nitrogen gas filter 12f". Therefore, it has been confirmed by experiments that "exhaust gas" whose oxygen concentration is 1/10 or less of that of the result of applying air can be extracted.

Furthermore, the inventors of the present application have also experimentally confirmed that in the "nitrogen gas filter 12f" used in the present embodiment, the lower the oxygen concentration of the gas to be filtered, the higher the recovery rate. Therefore, by using such a "nitrogen gas filter 12f" for filtering "exhaust gas" having an oxygen concentration lower than that of air, it is possible to further increase the recovery rate in high-purity nitrogen gas. This recovery rate will also be described in detail later.

Further, in the embodiment shown in FIG. 1, the nitrogen gas generation system 1 is
(A') Supply "air or a gas containing nitrogen and oxygen" having a pressure exceeding atmospheric pressure (1 atmospheric pressure (atm)) and "fuel gas" having a pressure exceeding atmospheric pressure to a "fuel cell". do it,
(B') From the "fuel cell", take out the "exhaust gas" that has a pressure exceeding atmospheric pressure and an oxygen concentration lower than that of air.
(C') It is possible to cause the "exhaust gas" to act on the "nitrogen gas filter 12f" with a pressure exceeding atmospheric pressure.

Here, the "nitrogen gas filter 12f" will be described again, but it is a filter using fibers having different degrees of permeation between nitrogen and oxygen, and the present inventors have said that (this will also be described in detail later). In a filter using fibers, it was confirmed by experiments that the higher the pressure of the acting "exhaust gas", the lower the oxygen concentration of the "exhaust gas" extracted from the filter, that is, the higher the purity of nitrogen gas. doing. From the viewpoint of such pressure control, the nitrogen gas generation system 1 can efficiently generate nitrogen gas having a low oxygen concentration, that is, high purity.

Incidentally, as will be described in detail later, the pressure of the "exhaust gas" acting on the "nitrogen gas filter 12f" is a pressure threshold determined by the "nitrogen gas filter 12f" and is the "nitrogen gas filter 12f". It has been confirmed by experiments that it is also preferable to set the pressure to a value exceeding the pressure threshold, which takes a larger value as the flow rate of the "exhaust gas" when taken out from the above.

Further, the nitrogen gas generation system 1 of the present embodiment generates high-pressure "exhaust gas" by using the "fuel cell" in the above-described embodiments (A') to (C'), and uses this to generate "exhaust gas". Since it acts on the "filter", it is not necessary to increase the pressure (at once) from atmospheric pressure to a desired high pressure (for example, 7 atm). As a result, it is possible to efficiently generate high-purity nitrogen gas.

Here, the wording "high purity" or "high purity" described above means a state in which the oxygen concentration in the nitrogen gas is sufficiently reduced. Specifically, the nitrogen concentration in the "high-purity" or "high-purity" nitrogen gas produced in the present embodiment (ml in 100 ml of the medium and the unit is vol%) is the field and application of the nitrogen gas. Depending on the situation, for example, it may be 95 vol% or more, 99 vol% or more, or 99.9 vol% or more.

[Configuration of nitrogen gas generation system]
Similarly, as shown in FIG. 1, the nitrogen gas generation system 1 of the present embodiment is
(A) A fuel cell U11 having a "fuel cell" and
(B) At a position in front of the fuel cell U11, a renewable energy power generation unit (U) 101, a storage U101s, a hydrogen generation U102, a hydrogen generation reforming U103, a hydrogen tank 104, a flow control U105, and air. Compression U106, air tank 107, filter U108, flow control U109,
(C) A drain 111, a pressure control U113, a gas-liquid separation U114, and a hydrogen recovery U115 are located at a position after the hydrogen electrode side of the fuel cell U11.
(D) A drain 112, a pressure control U121, a gas-liquid separation U122, an off-gas buffer tank 123, a pressure boosting U124, and a corrosive gas removal U125 are located at positions after the air electrode side of the fuel cell U11. , Temperature control U126, flow control U127, nitrogen filter U12 provided with nitrogen gas filter 12f, pressure boosting U128, nitrogen tank 129, and
(E) The system is equipped with an overall control U131, which incorporates natural energy such as air, water, and sunlight, and in some cases city gas, and even commercial electric power, to provide high-purity nitrogen gas. It is possible to supply electric power and thermal energy to the outside.

That is, the nitrogen gas generation system 1 of the present embodiment can also provide the electric power and thermal energy generated by the operated "fuel cell" to the outside in accordance with the generated nitrogen gas, and the nitrogen gas and the electric power. And it can also be regarded as a heat supply system (device).

The nitrogen gas generation system 1 can also be a single nitrogen gas generation device having the components shown above. Further, it is also possible to configure a nitrogen gas generator that includes at least the fuel cell U11, a component directly connected to the fuel cell U11, and a nitrogen filter U12, and at least the renewable energy power generation U101 is outside the device.

For example, all the components other than the renewable energy power generation U101, the storage U101s, the hydrogen generation U102, the hydrogen generation reforming U103, the hydrogen tank 104, the air compression U106, the air tank 107, the pressure boosting U128, and the nitrogen tank 129 are used as device components. It is also possible to configure a nitrogen gas generator.

Further, a nitrogen filter 12 provided with pressure control U121 to flow control U127, pressure boosting U124 to flow control U127, or corrosive gas removal U125 to flow control U127 as the first and second stages of filtering. It is also possible to configure a nitrogen gas generating device having it. Of course, a post-stage portion of the filtering process up to the nitrogen tank 129 may also be provided.

Further, such a nitrogen gas generator may be provided with a piping joint as an exhaust gas intake port which can be connected to, for example, an exhaust gas outlet of an externally installed "fuel cell", and the external "fuel cell" may be provided. It is also possible to use a device that takes in the exhaust gas discharged from the fuel gas and outputs the nitrogen gas having a reduced oxygen concentration. So to speak, it may be a "fuel cell-mounted filtering device" that can be attached to a "fuel cell".
[Possible invention claims]
A gas containing nitrogen and oxygen and having an oxygen concentration lower than that of air is allowed to act on a filter using fibers having different degrees of permeation for nitrogen and oxygen, and the gas having an increased nitrogen concentration is removed from the filter. A nitrogen gas generation method characterized by taking out.
[Possible invention claims]
An exhaust gas intake for receiving exhaust gas emitted from an external fuel cell,
A nitrogen gas which is a filter using fibers having different degrees of permeation for nitrogen and oxygen, and has a filter for outputting the exhaust gas having an increased nitrogen concentration by acting the received exhaust gas. Generator.

By the way, the substance / energy transfer and the flow of the processing to be performed shown by connecting the components in the system configuration diagram of FIG. 1 with arrows are also understood as an embodiment of the nitrogen gas generation method in the nitrogen gas generation system 1. Will be done.

Similarly, in FIG. 1, the renewable energy power generation unit U101 may be a solar power generation unit including a solar cell and converting sunlight into electric power, and a generator is rotated by rotating a rotor with blades (wings) by wind power. It may be a wind power generation unit that drives and generates electric power, or it may be a micro hydroelectric power generation unit that drives a generator by rotating a turbine (water wheel) by a water flow (hydraulic power) to generate electric power.

Further, various other power generation units can be adopted as the renewable energy power generation unit 101 as long as the light energy of sunlight and the kinetic energy of wind and water flow are finally converted into electric energy. Further, the renewable energy power generation unit 101 may be a combination of two or more of the power generation units as described above. In any case, it is also preferable that the output unit of the generated power is provided with a power meter so that the presence or absence of power generation and the amount of generated power can be measured at each time point.

The power storage U101s includes a secondary battery such as a lithium (Li) battery or a lead (Pb) storage battery, and is a power storage unit that stores and stores the electric power supplied from the renewable energy power generation unit 101. It is also preferable that the electricity storage U101s is provided with an electricity storage meter so that the amount of electricity stored at each time point and whether or not the battery is fully charged can be measured.

Here, electric power is supplied from the storage U101s to the hydrogen generation U102 and the air compression U106 (which electrolyzes water), which will be described later, but instead of or together with them, commercial electric power is the hydrogen generation U102 and the air. It may be supplied to the compressed U106.

Furthermore, there is a predetermined limit to the amount of electricity stored, and hydrogen generation U102 and air compression can be performed directly from the renewable energy power generation unit 101 without using the electricity storage U101s equipped with an expensive secondary battery (or to provide it as an auxiliary only). It is also preferable that power is supplied to the U106. In this case, the natural energy is directly converted into the chemical energy of hydrogen and the physical energy of compressed air and used.

When the renewable energy power generation unit 101 generates AC power (for example, when it is equipped with an AC generator), the AC power and commercial power are converted into direct current by a converter and then stored in storage U101s and hydrogen generation U102. Will be supplied to. Further, even when the air-compressed U106 includes the DC-driven compressor 22, it is converted to direct current and then supplied to the air-compressed U106.

In any case, the overall control U131 monitors the power supply to the hydrogen generation U102 and the air compressed U106 as described above, for example, the power generation status of the renewable energy power generation unit 101 and the power storage status of the storage U101s. , It is possible to switch and control appropriately.

Similarly, in FIG. 1, the hydrogen generation U102 is a hydrogen supply unit including an electrolysis unit capable of electrolyzing the acquired water with the supplied electric power to generate hydrogen and oxygen. Here, various known electrolysis methods can be adopted. For example, a method in which a large number of electrolytic cells having a structure in which a solid polymer electrolyte membrane is sandwiched between a catalyst and electrodes from both sides is used. Electrolysis may be performed.

Further, it is also preferable that the hydrogen generation U102 is provided with a dehumidifying portion for removing water from the generated hydrogen and oxygen. Further, a mechanism may be provided in which the water removed here is returned to the electrolysis section for electrolysis. It is also preferable to have a wattmeter that can measure the power consumed at each time point and the presence or absence of power consumption, and a flow meter or gas pressure gauge that can measure the amount of generated hydrogen and oxygen and the presence or absence of generation. You may have it.

Hydrogen production reforming U103 is introduced a hydrocarbon gas such as city gas or LPG, mixed with the hydrocarbon gas and steam, as a main component hydrogen (H ₂₎ by the steam reforming reaction from the mixed gas Produces hydrogen-containing gas. In addition, a mechanism for reducing the carbon monoxide gas content in the generated hydrogen-containing gas by using a CO modification catalyst or the like, or further reducing the carbon monoxide concentration by using a CO selective oxidation catalyst is provided. It is also preferable to have it.

By the way, when SOFC (Solid Oxide Fuel Cell) is adopted as the "fuel cell" of the fuel cell U11 described later, the high temperature (large calorific value) required for steam reforming in the hydrogen generation reforming U103 is used as this "fuel". It is also possible to cover it by exhausting heat from the "battery".

The nitrogen gas generation system 1 may include either hydrogen generation U102 or hydrogen generation reforming U103 as a hydrogen (fuel) supply source, or secures various supply sources. It is also preferable to have both as much as possible. Further, the hydrogen gas itself may be supplied from another system / device in place of or in combination with these sources.

The hydrogen tank 104 is a gas tank that temporarily stores and stores hydrogen gas supplied from hydrogen generation U102 and hydrogen generation reforming U103 in a compressed (high pressure) state, and is provided with a hydrogen storage alloy cylinder. May be good. It is also preferable that the hydrogen tank 104 is provided with a gas pressure gauge so that the gas pressure in the tank at each time point can be measured.

The flow control U105 is a unit that controls the pressure and flow rate of the hydrogen gas supplied from the hydrogen tank 104 to the fuel cell U11. Specifically, it may be provided with a hydrogen gas regulator and a hydrogen gas mass flow controller (or flow switch).

Here, the hydrogen gas may be supplied to the hydrogen electrode side of the fuel cell U11 in a state of high pressure (for example, 2 to 7 atm) having a pressure exceeding atmospheric pressure (1 atm). That is, in the present embodiment, the back pressure of the "fuel cell" provided in the fuel cell U11 can be set to a pressure exceeding the atmospheric pressure. The back pressure is 1 atm when the outlet side of the "fuel cell" is in the open state, that is, when the pressure of the exhaust gas is atmospheric pressure.

However, when a mass flow controller is used in the flow control U105, a pressure difference usually occurs here. Therefore, a regulator receives hydrogen gas having a pressure higher than the set pressure (back pressure), for example, about 1 to 2 atm, from the hydrogen tank 104. It is also preferable to flow the hydrogen gas to the mass flow controller after adjusting the pressure. Incidentally, it has been experimentally found that the above-mentioned pressure difference increases as the flow rate decreases (the flow is reduced).

Similarly, in FIG. 1, the air compression U106 is a unit including, for example, a compressor that compresses (makes high pressure) air taken in from the atmosphere and supplies it to the air tank 107. As a compression method in this compressor, various methods such as a reciprocating type, a scroll type, a screw type, a rotary type, a swing type, or a combination of two or more of these can be adopted.

The air tank 107 is a gas tank that temporarily stores and stores the compressed air supplied from the air-compressed U106 in a compressed state. It is also preferable that the air tank 107 is also provided with a gas pressure gauge so that the gas pressure in the tank at each time point can be measured.

The filter U108 includes an air filter and an oil filter, and is a unit for removing minute dust, oil components, and the like from the high-pressure air supplied from the air tank 107 by these filters.

The flow control U109 is a unit that controls the pressure and flow rate of compressed air supplied from the air tank 107 to the air electrode side of the fuel cell U11 via the filter U108. Specifically, it may be provided with a gas regulator and a mass flow controller (or flow switch).

Here, in the present embodiment, the compressed air is also a fuel (with a back pressure exceeding the atmospheric pressure) while being in a high pressure state (for example, 2 to 7 atmospheres) having a pressure exceeding the atmospheric pressure (1 atm). It may be supplied to the air electrode side of the battery U11. At this time, in consideration of the pressure difference of the mass flow controller, compressed air having a pressure higher than the set back pressure, for example, about 1 to 2 atm, is received from the air tank 107, the pressure is adjusted by the regulator, and then the compressed air is adjusted. May flow to the mass flow controller, as in the case of the hydrogen gas described above.

Similarly, in FIG. 1, the fuel cell U11 is provided with a "fuel cell", and exhaust gas, electric power, heat, and water (steam) having an oxygen concentration lower than that of air are extracted from the "fuel cell" and output. It is a unit to do.

Of course, the fuel cell U11 can be used by setting the back pressure of the "fuel cell" to 1 atm (atmospheric pressure), but as one preferred embodiment,
(A) Back pressure exceeding atmospheric pressure (for example, 2 to 7 atmospheres) is set.
(B) Receive hydrogen gas having a pressure exceeding atmospheric pressure (for example, 2 to 7 atmospheres) from the flow control U105, and further, compressed air having a pressure exceeding atmospheric pressure (for example, 2 to 7 atmospheres) from the flow control U109. Receive and operate,
(C) It is also preferable that the unit is provided with a "fuel cell" that discharges exhaust gas having a pressure exceeding atmospheric pressure (for example, 2 to 7 atmospheres).

Here, this "fuel cell" can have a known configuration, for example, an electrolyte is sandwiched between a hydrogen electrode (fuel electrode, anode, anode) and an air electrode (oxygen electrode, cathode, cathode). The cells having a structure may have a structure in which a plurality of cells are stacked (stacked) with a separator in between.

Further, as the battery system in the "fuel cell", a solid polymer fuel cell (PEFC), a solid oxide fuel cell (SOFC), a phosphoric acid fuel cell (PAFC), and a molten carbonate fuel cell (MCFC) ) Etc. can be adopted. Of these, SOFCs have high power generation efficiency, usually operate at about 700 to about 1000 ° C., and can supply exhaust gas at a considerably high temperature. As described above, when hydrogen gas is generated from city gas or the like by using the hydrogen reforming U103, SOFC can supply a large amount of heat required for the steam reforming. Further, the PEFC method is used in many fuel cell vehicles, for example, because it operates at a relatively low temperature and the battery size can be made compact.

When the "fuel cell" in the fuel cell U11 is PEFC, for example, the JARI type fuel cell developed for research and development by the Japan Automobile Research Institute (JARI) is referred to as "fuel cell". It is also possible to adopt it as. The JARI type fuel cell has a structure in which the back pressure can be increased and pressure can be applied to the inside of the battery, and on top of that, all the exhaust gas having a high back pressure can be recovered.

Here, in the present embodiment, the pressure in the "fuel cell", that is, the back pressure, is adjusted and controlled by the back pressure valve of the pressure control U113 and the back pressure valve of the pressure control U121, which will be described later.
(A) The back pressure on the hydrogen electrode side, which is mainly adjusted by the back pressure valve of the pressure control U113,
(B) It is also preferable that the back pressure on the air electrode side, which is mainly adjusted by the back pressure valve of the pressure control U121, is controlled to be substantially the same. In fact, if there is a difference of about 0.1 atm between both back pressures, a slight gas leak may occur from the "fuel cell", while if both back pressures are equal, even a considerably high back pressure is a problem. It is experimentally known that it does not occur. In particular, when the "fuel cell" is PEFC, the electrolytic film is relatively thin, so it is more preferable to make both back pressures equal.

Further, the fuel cell U11 provided with the "fuel cell" as described above has the amount, pressure and temperature of hydrogen gas / compressed air flowing into the "fuel cell", and the exhaust gas discharged from the "fuel cell". It is equipped with a measurement system / sensor group that can measure the amount of exhaust water vapor / moisture, pressure and temperature, and further, the overall control U131 that receives information from the measurement system / sensor group operates the "fuel cell". Is also preferably controlled.

Further, in the fuel cell U11, a heat exchanger that circulates a heat exchange medium such as water is arranged in or around the "fuel cell", and heat is taken out from the "fuel cell" that has been operated and generated heat to the outside of the unit. It is also preferable to transfer it. Alternatively, instead of the heat exchanger, the heat inside the "fuel cell" can be taken out directly to the outside by using a thermoelectric system in which the conductive separator and the heat pipe in the "fuel cell" are connected.

Incidentally, the heat transferred by the heat exchange medium or the heat pipe in this way is supplied not only to the outside but also to the inside of the system and can be used, and in the present embodiment, it is supplied to the off-gas buffer tank 123 described later. Therefore, the exhaust gas supplied to the nitrogen filter U12 can be heated to a higher temperature (for example, 45 ° C.). Of course, when the temperature of the exhaust gas is sufficiently high, such heat treatment in the off-gas buffer tank 123 becomes unnecessary.

Further, the heat can be transferred to the hydrogen reforming U103 by such a heat exchange medium or a heat pipe to replenish the amount of heat required for steam reforming. Further, the heat can be used to turn the water to be electrolyzed in the hydrogen generation U102 into steam or raise the temperature of the water to improve the hydrogen generation efficiency in electrolysis.

At this time, in order to achieve the desired hydrogen generation efficiency and maintain it stably, it is also preferable to monitor the temperature of the electrolysis cell with an installed temperature sensor and control the electrolysis operation by the overall control U131. Further, it is also possible to increase the applied voltage between the electrodes so that the electrolysis treatment can be performed without using the electrolyte and without the need for monitoring or maintenance of the electrolyte.

Furthermore, as another embodiment of the fuel cell U11, two or more "fuel cells" are connected in series, and the exhaust gas of the previous fuel cell is sequentially taken in and used for the battery reaction, thereby finally. It is also easy to take out the exhaust gas having a lower oxygen concentration, for example, the exhaust gas having an oxygen concentration of 2.5 vol% or less. Incidentally, the inventors of the present application have published the invented fuel cell system having such a configuration in Japanese Patent Application Laid-Open No. 2019-129110.

Similarly, in FIG. 1, drains 111 and 112 are provided at the fuel passage outlet (on the hydrogen electrode side) and the air passage outlet (on the air electrode side) of the "fuel cell" in the fuel cell U11, respectively, and have a relative humidity (usually, relative humidity). (Approximately 100%) Recovers water generated by condensation of water vapor contained in the exhaust gas. As a result, the adverse effect on the battery reaction due to the so-called flooding phenomenon can be suppressed. Further, the water recovered in this way may be sent to the hydrogen generation U102 and reused as a hydrogen generation material.

Here, by setting the back pressure of the "fuel cell" to a value exceeding the atmospheric pressure (for example, 2 to 7 atm), the dew point is raised to increase the amount of water falling into the drains 111 and 112, and the dehumidifying effect is enhanced. It can also be increased. It is also preferable that the drains 111 and 112 have an auto-drain function that automatically discharges the water to the outside when a predetermined amount of water is accumulated. An example of the dehumidifying treatment in the drain 112 will be described in detail later with reference to FIG.

The pressure control U113 flows the hydrogen gas dehumidified at the drain 111 toward the fuel passage inlet (on the hydrogen electrode side) of the “fuel cell” while maintaining the set back pressure of the “fuel cell” (for example, flow). (After the control U105), for example, a unit for returning via a hydrogen mixer. Specifically, the pressure control U113 includes a back pressure valve and a pressure gauge, and by adjusting the back pressure valve, the pressure (back pressure) in the "fuel cell", particularly on the hydrogen electrode side, is controlled.

The gas-liquid separation U114 is for removing residual water vapor and water from the exhaust gas discharged from the fuel passage outlet (on the hydrogen electrode side) of the "fuel cell" and passing through the drain 111 and the pressure control U113. It is a unit. Specifically, a dehumidifier, a dry filter, a dehumidifier equipped with a pressurizing mechanism, and a gas-liquid separator can be used to remove water vapor and water. Here, as the dehumidifier, one containing silica gel and / or zeolite can be used. Further, as a gas-liquid separator type, a gravity separation type, a centrifuge type, a mist remover pad type, an airfoil type separation type, an atmospheric pressure separation corelesser type, or the like can be adopted.

The hydrogen recovery U115 is a unit for taking out unreacted residual hydrogen gas from the exhaust gas discharged from the fuel passage outlet (on the hydrogen electrode side) and reusing it by using a known hydrogen gas filter or executor. Here, the hydrogen gas taken out can be sent back to, for example, the hydrogen mixer at the subsequent stage of the flow control U105. Further, the gas after taking out the hydrogen gas may be discharged to the outside.

Similarly, in FIG. 1, the pressure control U121 is a unit for sending the exhaust gas (on the air electrode side) dehumidified by the drain 112 to the gas-liquid separation U122 while maintaining the set back pressure of the “fuel cell”. be. Specifically, this pressure control U121 also has a back pressure valve and a pressure gauge like the pressure control U113, and by adjusting the back pressure valve, the pressure (back pressure) in the "fuel cell", particularly on the air electrode side, is controlled. To do.

The gas-liquid separation U122 still remains from the high pressure (eg 2-7 atm) exhaust gas that has been discharged from the air passage outlet (on the air electrode side) of the "fuel cell" and has passed through the drain 112 and the pressure control U121. It is a unit for removing water vapor and water. Specifically, the fact that water vapor and water can be removed by using a dehumidifier, a dry filter, a dehumidifier provided with a pressurizing mechanism, and a gas-liquid separator is the same as the gas-liquid separation U114 described above. Incidentally, as one criterion, it is also preferable that the gas-liquid separation U122 suppresses the relative humidity in the exhaust gas to 20 to 30% or less.

In particular, in the embodiment in which the back pressure of the "fuel cell" is not increased (for example, 2 atm or less), the gas-liquid separation U122 cannot be expected to increase the amount of recovered water in the drain 112 due to the increase in the dew point. It will be a very important unit. However, as one embodiment, when the exhaust gas discharged from the drain 112 is stored in the off-gas buffer tank 123, which will be described later, the tank is brought into a high pressure state by, for example, a compression (pressure boosting) device provided in front of the tank. It is also possible to dehumidify by the auto drain installed in 123. In this case, the gas-liquid separation U122 may be omitted.

The off-gas buffer tank 123 is a gas tank that temporarily stores and stores the exhaust gas introduced from the gas-liquid separation U122. This exhaust gas is introduced into the off-gas buffer tank 123 until the pressure becomes the same as the set back pressure (for example, 2 to 7 atm). Further, in order to allow the exhaust gas to flow into the nitrogen filter U12 described later at a desired pressure (for example, 7 atm), the flow rate of the exhaust gas to the off-gas buffer tank 123 is equal to or equal to the required introduction flow rate to the nitrogen filter U12. It is also preferable to set the flow rate to exceed the flow rate.

Incidentally, when the "fuel cell" is stopped, the pressure inside the pipe to the off-gas buffer tank 123 returns to, for example, atmospheric pressure. Therefore, it is also preferable that the off-gas buffer tank 123 is provided with a check valve for preventing the backflow of the exhaust gas to the "fuel cell". It is also preferable that the off-gas buffer tank 123 is also provided with a gas pressure gauge so that the gas pressure in the tank at each time point can be measured.

Further, the off-gas buffer tank 123 uses a "heating means" capable of heat treatment by the heat generated by the "fuel cell" in the fuel cell U11 to heat the exhaust gas in the tank to a temperature higher than room temperature (for example, 30 to 45 ° C.). ) Is also preferable. This makes it possible to supply the exhaust gas at a temperature suitable for the nitrogen filtering process to the nitrogen gas filter 12f of the nitrogen filter U12, which will be described later.

Here, as the above-mentioned "heating means", the heat exchanger already described or the separator / heat pipe connecting system may be adopted. This makes it possible to effectively utilize the heat of the "fuel cell" and carry out a suitable nitrogen filtering process without using an energy consuming means such as an electric heater. Of course, when the temperature of the exhaust gas introduced into the off-gas buffer tank 123 is sufficiently high, such a "heating means" becomes unnecessary.

The pressure boosting U124 further boosts the pressure (for example, at a pressure of 7 atm) the exhaust gas extracted from the “fuel cell” of the fuel cell U11 and supplies it to the nitrogen filter U12. As the pressure booster U124, a known pressure booster valve, for example, a pressure booster valve VB11A or VBA42 for an inert gas manufactured by SMC Corporation can be adopted. It is also preferable to have a pressure gauge for monitoring the exhaust gas pressure increase.

Here, most of the known pressure boosting valves are of the air drive type, but in this case, a part of the compressed air supplied to the "fuel cell", that is, the compressed air taken out from the air tank 107 is used as the support gas. , This booster valve may be driven. As a result, it is not necessary to impose a burden such as further power consumption on driving the booster valve. It is also preferable to use a booster type compressor as the booster U124.

Incidentally, as described above, when the pressure of the exhaust gas from the off-gas buffer tank 123 is sufficiently high (for example, 7 atm), the boosting U124 is of course unnecessary. Further, although care must be taken in handling, the hydrogen gas taken out from the hydrogen tank 104 can also be used as this support gas.

Similarly, in FIG. 1, the corrosive gas removal U125 is subsequently subjected to sulfide, chloride, and hydrocarbons with respect to the exhaust gas (taken out from the “fuel cell”) to act on the nitrogen gas filter 12f of the nitrogen filter U12. A unit capable of being treated to remove or reduce at least one of hydrogen, fluoride and a strong alkaline compound.

For example, when hydrogen gas is generated from city gas or the like using hydrogen generation reforming U103 and the hydrogen gas is used as a fuel for a "fuel cell", the exhaust gas includes hydrocarbons such as hydrogen sulfide, sulfite gas, and methane gas. Various gas components other than hydrogen gas, such as gas, ammonia, and formaldehyde, are mixed. Further, when SOFC is used for the "fuel cell", nitrogen gas in the air may combine with oxygen in a high temperature atmosphere of about 800 ° C., and nitrogen oxides (NOx) may be generated. These gases not only become impurities in the final product nitrogen gas, but also pose a risk of adversely affecting the fibers (of the hollow fibers) of the nitrogen gas filter 12f.

Therefore, the corrosive gas removal U125 is provided with, for example, an activated carbon filter, and plays a role of removing or reducing the above-mentioned impurity gas in the exhaust gas as much as possible. By the way, as one standard for removing corrosive gas, etc., the concentration of hydrocarbon gas is ^{suppressed to 0.013 mg / Nm 3} (0.01 ppm wt) or less, and strong acidity of hydrogen sulfide, sulfite gas, hydrogen chloride, fluorine, etc. It is also preferable to keep the concentration of the gas and the strongly alkaline gas such as amine, ammonia and caustic soda below the detection limit in the predetermined detection method.

Further, as shown in FIG. 1, it is also preferable that a mist filter and a dust filter are installed before and after the corrosive gas removal U125. Of these, the mist filter is a filter that removes or reduces mist such as water mist, solvent mist, and oil mist in the exhaust gas. As one standard, this mist filter preferably keeps the concentration of residual oil from these mists to 0.01 mg / Nm ³ (0.008 ppm wt) or less. On the other hand, the dust filter is a filter that removes or reduces dust in the exhaust gas. As one standard, the dust filter preferably excludes almost all particles having a particle size of 0.01 μm or more.

The temperature control U126 is provided with, for example, an electric heater, and the temperature of the taken-in exhaust gas is brought close to or matched with a preset suitable temperature based on the characteristics of the nitrogen gas filter 12f, and the temperature-adjusted exhaust gas is sent to the nitrogen filter U12. It is a unit for supplying. Further, as a preferred embodiment, the temperature control U126 may receive the heat supplied from the fuel cell U11 via the heat exchanger and use it for temperature control, or is also supplied from the fuel cell U11. The exhaust gas temperature may be adjusted by electric power.

Incidentally, the UBE N ₂ separator NM-B01a of Ube Industries can be employed as a nitrogen gas filter 12f to be described later, the filtering when the temperature of the introduced gas is 30-45 ° C. above room temperature (25 ° C.) It is said that the effect will be higher. In this case, when the exhaust gas of the "fuel cell" is higher than the room temperature (25 ° C.), it is possible to enjoy this high filtering effect without using the temperature control U126. In addition, it is possible to suppress the power consumption for temperature adjustment by that amount.

It is also known that in the nitrogen gas filter 12f using fibers having different degrees of permeation for nitrogen and oxygen, the recovery rate is greatly reduced as the temperature of the introduced exhaust gas rises. Therefore, depending on the content of the nitrogen gas output performance set in this system, in order to secure a predetermined recovery rate, the temperature of the exhaust gas is generally kept at the temperature inside the off-gas buffer tank 123 without using the temperature control U126. It is possible to do so.

Similarly, in FIG. 1, the nitrogen filter U12 causes the exhaust gas supplied from the flow control U127 to act on the nitrogen gas filter 12f using fibers having different degrees of permeation for nitrogen and oxygen, and from the nitrogen gas filter 12f. It is a unit that takes out exhaust gas having an increased nitrogen concentration, that is, high-purity nitrogen gas in the present embodiment.

Specifically, in the present embodiment, the nitrogen filter U12 is
(A) Nitrogen gas filter 12f and
(B) A filter input / output unit that introduces exhaust gas to act on the nitrogen gas filter 12f and extracts exhaust gas with an increased nitrogen concentration from the nitrogen gas filter 12f.
(C) A filter purge unit that takes out a gas containing oxygen molecules (hereinafter abbreviated as filter exhaust gas) separated from nitrogen molecules (in the exhaust gas) by the nitrogen gas filter 12f separately from the exhaust gas taken out in the above (b). And have.

Specifically, as the nitrogen gas filter 12f, a hollow fiber filter (hollow fiber fiber filter) using a polymer fiber material that allows oxygen molecules to permeate more preferentially than nitrogen molecules can be used. For example, it may be employed Ube Industries of UBE _{N 2} separator NM-B01a with polyimide hollow fibers. This is a mechanism in which oxygen molecules selectively permeate the hollow fiber membrane while the high-pressure exhaust gas flows through the hollow fiber, and finally, nitrogen gas with increased purity is taken out from the outlet of the hollow fiber. It has become. Of course, the nitrogen gas filter 12f is not limited to this separator, and for example, a UBE N2 separator NM series separator manufactured by Ube Industries and a Sepuran N2 membrane module manufactured by Daicel Evonik are adopted as the nitrogen gas filter 12f. It is also possible to do.

Here, in such a nitrogen gas filter 12f,
(A) Oxygen concentration of the introduced exhaust gas (introduced oxygen concentration), pressure of the introduced exhaust gas (introduced pressure), flow rate of the exhaust gas at the outlet of the filter 12f (outlet flow rate),
(B) The relationship between the oxygen concentration of the exhaust gas at the outlet of the filter 12f (outlet oxygen concentration) and the recovery rate of the filter 12f will be described in detail later with reference to the examples shown in FIGS. 3 to 5. Therefore, various conditions for obtaining high-purity nitrogen gas will also be described.

The outlet flow rate of (a) above can be measured by a flow meter installed on the outlet side of the nitrogen filter U12 and controlled by a flow control U127 described later. Further, the outlet oxygen concentration in (b) above can also be measured by an oxygen concentration meter installed on the outlet side of the nitrogen filter U12. Here, of course, it is also preferable that the flow control U127 is installed immediately after these oxygen concentration meters and flow meters.

Further, in the present embodiment, the overall control U131 controls, for example, the back pressure valve of the pressure control U121 to adjust the set back pressure of the "fuel cell" based on the measured value of the outlet oxygen concentration by the oxygen concentration meter. By controlling the mass flow controller of the flow control U127 to adjust the flow rate of exhaust gas to the "filter", it is possible to supply high-purity nitrogen gas having a desired extremely low oxygen concentration.

Similarly, in FIG. 1, the flow control U127 controls the flow rate of the exhaust gas having an increased nitrogen concentration generated by the nitrogen filter U12, that is, the high-purity nitrogen gas in the present embodiment, and boosts the pressure of the nitrogen gas. It is a unit that sends to the nitrogen tank 129 via U128. That is, as described above, it is a unit that controls the outlet flow rate (f_out) in the nitrogen gas filter 12f. Specifically, it may be provided with a gas regulator and a mass flow controller (or flow switch).

In the present embodiment, the pressure boosting U128 further increases the pressure of the high-purity nitrogen gas whose flow rate is controlled by the flow control U127 (for example, at a pressure of 8 to 15 atm) and sends it to the nitrogen tank 129 in a larger amount. It is a unit for storing and storing high-purity nitrogen gas in a nitrogen tank 129. As the pressure boosting U128, for example, a boost pressure boosting valve or a boost compressor can be adopted. It is also preferable that a pressure gauge is provided for monitoring the pressure increase.

Further, the nitrogen tank 129 temporarily stores and stores the high-purity nitrogen gas supplied from the nitrogen filter U12 via the pressure boosting U128, and stably externally stores the high-purity nitrogen gas according to, for example, the control by the overall control U131. It is a nitrogen gas supply interface that supplies to. It is also preferable that the nitrogen tank 129 is also provided with a gas pressure gauge so that the gas pressure in the tank at each time point can be measured.

Even if the nitrogen tank 129 (and the pressure boosting U128) as such a nitrogen gas supply interface is not used and the generated nitrogen gas is directly supplied from the nitrogen filter U12 via a predetermined flow control means to the outside. good. For example, when this supply destination is a soldering device or the like, high-purity nitrogen gas that is directly supplied and has a temperature exceeding at least room temperature (25 ° C.) can be used as a soldering atmosphere to further increase the temperature. It is more preferable because it can save the required amount of heat.

The overall control U131 is capable of communicating with the main components including the fuel cell U11 and the nitrogen filter U12 described above, preferably all the components, via a wired or wireless communication network, and each configuration. Measures of the unit ・ Receives the measured quantities output from the sensor, such as pressure, gas flow rate, temperature, nitrogen concentration, oxygen concentration, hydrogen concentration, presence or absence of hydrogen leakage, etc., and monitors them as appropriate to monitor and monitor each component. It is a control unit that performs control.

For example, the overall control U131 includes a processor and a memory, and the memory stores and mounts a nitrogen gas generation system monitoring / control program for monitoring / controlling each component, and this processor. It is also preferable that the program is executed by.

Here, the control performed by the overall control U131 includes adjustment / control of pressure, gas flow rate, temperature, nitrogen concentration, oxygen concentration, hydrogen concentration, etc. between each component and each component. In particular, it is also preferable to control the back pressure in the "fuel cell" of the fuel cell U11 and to control the balance between the back pressure on the hydrogen electrode side and the back pressure on the air electrode side.

Further, the overall control U131 monitors the temperature (cell temperature) of the "fuel cell" of the fuel cell U11, the temperature of the exhaust gas introduced into the nitrogen gas filter 12f of the nitrogen filter U12, the temperature of the hydrogen generating U102, and the like. Therefore, it is also preferable to appropriately control the fuel cell reaction, the filtering operation, and the hydrogen generation (electrolysis) reaction in the nitrogen gas generation system 1. Further, it is also preferable to monitor the presence or absence of hydrogen leakage between each component and each component, and when it is determined that a problem has occurred, send an alarm including information on the hydrogen leak location to the outside.

[Example 1]
2 to 4 are graphs for explaining Example 1 according to the nitrogen gas generation treatment according to the present invention.

In Example 1 showing the measurement results and analysis results in FIGS. 2-4, using Ube Industries of UBE _{N 2} separator NM-B01a as a nitrogen gas filter 12f (FIG. 1), with respect to the nitrogen gas filter 12f , At room temperature (25 ° C), the oxygen concentration is 10.3vol%, 5.1vol%, and 1.1vol%, respectively, which is a mixed gas of nitrogen gas and oxygen gas and air having an oxygen concentration of 20.8vol%. Introducing each of the mixed gases of the seeds individually,
(A) The oxygen concentration of the introduced gas (introduced oxygen concentration c_in_O2 (vol%)), the pressure of the introduced gas (introduced pressure p_in (atmospheric pressure)), and the flow rate of the exhaust gas at the outlet of the nitrogen gas filter 12f (outlet flow rate f_out (outlet flow rate f_out). L / min, liter / minute)) and
(B) The oxygen concentration of the gas at the outlet of the nitrogen gas filter 12f (outlet oxygen concentration c_out_O2 (ppm vol)) was measured, and the relationship between the above (a) and (b) was investigated.

By the way, the oxygen concentrations of 10.3vol%, 5.1vol%, and 1.1vol% in the above-mentioned introduced gas are all the values realized in the exhaust gas of the actual "fuel cell".

2 (A), (B) and (C) show the introduced oxygen concentration c_in_O2 and the outlet oxygen concentration under the conditions of outlet flow rates f_out of 2.0 L / min, 1.5 L / min, and 1.0 L / min, respectively. A graph showing the relationship with c_out_O2 is shown.

According to these graphs
(A) The smaller the introduced oxygen concentration c_in_O2, the more
(B) The larger the introduction pressure p_in, the more
(C) The smaller the outlet flow rate f_out, the smaller
It is understood that the outlet oxygen concentration c_out_O2 becomes smaller and more pure nitrogen gas is output from the nitrogen gas filter 12f.

For example, when the introduced oxygen concentration c_in_O2 is 1.1%, the introduced pressure p_in is 7.0 atm, and the outlet flow rate f_out is set to 1.0 L / min (the graph points shown in FIG. 2C), the outlet oxygen The concentration c_out_O2 is 325ppm (0.0325vol%). By the way, under the same introduction oxygen concentration and introduction pressure condition, when the outlet flow rate f_out is set to 0.75 L / min, which is even smaller, the outlet oxygen concentration c_out_O2 becomes a very small value of 190 ppm (0.0190 vol%). It is also known that high-purity nitrogen gas with extremely low oxygen concentration can be obtained. Incidentally, it has been experimentally confirmed that the tendency of such a result is almost the same even when the temperature of the gas introduced into the nitrogen gas filter 12f is 40 ° C. and 50 ° C.

<Outlet flow rate and outlet oxygen concentration>
First, a more specific relationship between the outlet flow rate f_out and the outlet oxygen concentration c_out_O2 will be described. From the data of the graphs shown in FIGS. 2 (A) to 2 (C), the following equation (1) (c_out_O2) = C · (f_out) ^a
It is derived that the relationship represented by is established. here,
(A) The term coefficient C takes a positive value, and the smaller the introduced oxygen concentration c_in_O2 and the larger the introduced pressure p_in, the smaller the value. For example, when the introduced oxygen concentration c_in_O2 is 1.1% and the introduced pressure p_in is 7.0 atm, this C value is 319 (ppm), which is a very small value. on the other hand,
(B) The power coefficient a hardly depends on the introduced oxygen concentration c_in_O2, and the introduced pressure p_in becomes around 1.6 at 4.0 atm, and the larger the introduced pressure p_in, the larger the value, and the introduced pressure p_in becomes 7.0 atm. It will be around 2.0.

Therefore, in any case, it is understood that the smaller the outlet flow rate f_out, the smaller the outlet oxygen concentration c_out_O2, that is, a high-purity nitrogen gas having a lower oxygen concentration can be obtained. Here, since the power coefficient a is determined only by the introduction pressure p_in, the mechanism of contribution of the outlet flow rate to the outlet oxygen concentration is a dynamic one related to the fiber state of the filter 12f determined by the introduction pressure. it is conceivable that.

<Introduced oxygen concentration and filtering effect>
Next, using the analysis results shown in FIG. 3, the relationship between the introduced oxygen concentration c_in_O2 and the filtering effect of the nitrogen gas filter 12f, that is, the degree of the oxygen concentration reducing effect will be described.

3 (A), (B) and (C) show the introduced oxygen concentration c_in_O2 and the oxygen concentration under the conditions that the outlet flow rates f_out are 2.0 L / min, 1.5 L / min, and 1.0 L / min, respectively. A graph showing the relationship with the reduction index is shown. The four graph curves shown in each of these graphs are approximation curves for data points when the introduction pressure p_in is 4.0 atm, 5.0 atm, 6.0 atm, and 7.0 atm, respectively.

Here, the oxygen concentration reduction index is based on the following equation (2) (oxygen concentration reduction index) = c_out_O2 (Air), where the outlet oxygen concentration when air having an oxygen concentration of 20.8 vol% is introduced into the nitrogen gas filter 12f is c_out_O2 (Air). Air) / c_out_O2
It is an index calculated by, and represents the degree of absolute oxygen concentration reduction by filtering based on the result of applying air, that is, the magnitude of the filtering effect (relative to the case of air). It is an index.

According to the graphs of FIGS. 3 (A), (B) and (C),
(A) The oxygen concentration reduction index increases as the introduced oxygen concentration c_in_O2 decreases, and the rate of increase increases sharply, especially when the introduced oxygen concentration c_in_O2 exceeds 10 vol%.
(B) The oxygen concentration reduction index does not show a significant dependence on the introduction pressure p_in, and further
(C) It can be seen that the oxygen concentration reduction index does not show a significant dependence on the outlet flow rate f_out. Incidentally, the introduced oxygen concentration c_in_O2 = 10vol% at which the rate of increase of the oxygen concentration reduction index in (a) above begins to increase rapidly corresponds to the oxygen concentration in the exhaust gas of the "fuel cell" having an oxygen utilization rate of 50%.

From the above analysis results, for example, a filtering condition such that the oxygen concentration reduction index is 10, that is, the filtering effect is 10 times (compared to the case of air) is obtained (one digit higher). It is understood that the introduced oxygen concentration c_in_O2 should be 2.5 vol% or less regardless of the setting of the introduced pressure p_in and the outlet flow rate f_out. Here, the value of c_in_O2 = 2.5vol% is the average value of the introduced oxygen concentration values at which the oxygen concentration reduction index is 10 in the four power approximation curves in each graph. By the way, the intercept on the horizontal axis of the tangent line around c_in_O2 = 1.1vol% in the graph curve of each graph is also a value near this 2.5vol% (= c_in_O2).

Therefore, in the nitrogen gas generation system 1 of the embodiment shown in FIG. 1, the exhaust gas having an oxygen concentration of 2.5 vol% or less is allowed to act on the nitrogen gas filter 12f, so that air is allowed to act from the filter 12f. It is also possible to extract exhaust gas whose oxygen concentration is 1/10 or less of that of the result. By the way, with respect to the graph of FIG. 3 described above, it was confirmed by experiments that even when the temperature of the gas introduced into the nitrogen gas filter 12f was 40 ° C. and 50 ° C., they were almost the same especially in the low oxygen concentration region. Has been done.

<Introduction pressure and outlet oxygen concentration>
Next, the relationship between the introduction pressure p_in and the outlet oxygen concentration c_out_O2 will be described using the analysis results shown in FIG.

FIG. 4 shows the ratio of the quadratic coefficient and the linear coefficient in the four polynomial (quadratic) approximation formulas corresponding to the four graph curves in each of the graphs shown in FIGS. 2 (A) to 2 (C). In,
It is a graph showing the relationship between the introduction pressure p_in and (secondary coefficient) / (first order coefficient).

Here, in each graph shown in FIGS. 2 (A) to 2 (C), the introduced oxygen concentration c_in_O2 and the outlet oxygen concentration c_out_O2 when the introduced pressure p_in is 4.0 atm, 5.0 atm, 6.0 atm and 7.0 atm, respectively. Four graph curves showing the relationship with the graph curve are shown, and a polynomial (quadratic) approximation formula corresponding to the graph curve is described in the vicinity of each graph curve. For example, in the vicinity of the graph curve of p_in = 7.0 atm (and f_out = 1.0 L / min) in the graph of FIG. 2 (C),
(3) y = 6.6246 x ² + 161.96
Where y is c_out_O2 (vol%) and x is c_in_O2 (vol%)
In this case, the second-order coefficient is 6.6246 and the first-order coefficient is 161.96.

As described above, it can be seen that the introduced oxygen concentration c_in_O2 not only contributes (proportionally) to the outlet oxygen concentration c_out_O2 as a primary term, but also affects it as a secondary term. That is, if the introduced oxygen concentration c_in_O2 is reduced to 1/N, the outlet oxygen concentration c_out_O2 is not simply reduced to 1/N, and the quadratic term of the introduced oxygen concentration c_in_O2 is effective for the outlet oxygen concentration c_out_O2. It is.

The (second-order coefficient) / (first-order coefficient), which is the value of the ratio of the second-order coefficient to the first-order coefficient as described above, is obtained for each graph curve of each graph of FIGS. 2 (A) to 2 (C). After the calculation, the vertical axis is (secondary coefficient) / (first order coefficient), and the horizontal axis is the introduction pressure p_in, and the graph obtained by plotting these calculated values is the graph of FIG.

According to the graph of FIG. 4, three graph curves (straight lines in FIG. 4) having outlet flow rates f_out of 1.0 L / min, 1.5 L / min and 2.0 L / min are obtained, respectively, and the graph points of FIG. 4 are obtained. Can be approximated by a linear approximation formula determined for each outlet flow rate.

According to these graph curves (straight lines), the larger the introduction pressure p_in and the smaller the outlet flow rate f_out, the larger the (secondary coefficient) / (first order coefficient). Therefore, it can be seen that the quadratic term of the introduced oxygen concentration c_in_O2 described above contributes to making the outlet oxygen concentration c_out_O2 smaller.

From this, in order to obtain a higher-purity nitrogen gas (make the outlet oxygen concentration c_out_O2 smaller), the ratio of the quadratic term in the introduced oxygen concentration c_in_O2, that is, the (secondary coefficient) / (first-order coefficient) is set. , It is preferable to make it larger in the positive value, and it is understood that it is important to make it at least a value exceeding 0 (zero) at which the contribution of the quadratic term disappears. That is, it is preferable to express a secondary term exceeding a positive value.

Therefore, when the condition that the (secondary coefficient) / (first-order coefficient) exceeds 0 (zero) was obtained from the graph of FIG. 4, the outlet flow rates f_out were 1.0 L / min, 1.5 L / min, and 2.0. It can be seen that the condition is that the introduction pressure p_in exceeds 2.94 atm, 3.40 atm, and 3.86 atm, respectively, in the case of L / min. Here, it is also understood that these pressure threshold values take a larger value as the outlet flow rate f_out increases. That is, when the outlet flow rate f_out is set smaller, the introduction pressure p_in can be set based on the smaller pressure threshold value.

Further, from the above analysis results, in the nitrogen gas generation system 1 of the embodiment shown in FIG. 1, the pressure (introduction pressure) of the exhaust gas acting on the nitrogen gas filter 12f is determined by the nitrogen gas filter 12f. It is understood that it is also preferable to set the pressure to a value exceeding the pressure threshold, which is a threshold value and takes a larger value as the flow rate (outlet flow rate) of the exhaust gas when taken out from the nitrogen gas filter 12f increases.

[Example 2]
FIG. 5 is a graph for explaining Example 2 in which the recovery rate of the nitrogen gas filter 12f in the nitrogen gas generation treatment according to the present invention was investigated.

In Example 2, the same system as in Example 1 was used, and the same conditions were set for the introduced oxygen concentration, the introduced pressure, and the outlet flow rate as in Example 1, and the recovery rate of the nitrogen gas filter 12f was measured. ing. However, in the second embodiment, the measurement when the introduced oxygen concentration c_in_O2 = 0 (zero), that is, the measurement by introducing pure nitrogen gas into the filter 12f is additionally performed. Further, here, the recovery rate, which is the measurement item of the second embodiment, is the degree / degree of gas recovery in the filter 12f, and the flow rate (introduction flow rate) of the introduced gas at the inlet of the filter 12f is f_in, and the following equation (4) ) (Recovery rate) = (f_out) / (f_in)
It is the value of the ratio calculated by.

5 (A), (B) and (C) show the introduced oxygen concentration c_in_O2 and the recovery rate under the conditions of outlet flow rates f_out of 2.0 L / min, 1.5 L / min, and 1.0 L / min, respectively. A graph showing the relationship between is shown.

According to these graphs
(A) The smaller the introduced oxygen concentration c_in_O2 (although it may deviate slightly under the condition of 4.0 atm), the more
(B) The smaller the introduction pressure p_in (although the difference between 4.0 atm and 5.0 atm is very small), the more
(C) (This is highly probable from the definition of recovery rate) The larger the outlet flow rate f_out, the higher the probability.
It can be seen that the recovery rate becomes higher, and for example, even if an exhaust gas having a predetermined flow rate is introduced into the nitrogen gas filter 12f, a larger amount of nitrogen gas (exhaust gas having a reduced oxygen concentration) is obtained.

Here, regarding the introduced oxygen concentration c_in_O2 in (a) above, the direction of increasing the recovery rate and the direction of decreasing the outlet oxygen concentration c_out_O2 (as shown in FIG. 2, for example) are the same, and are concrete. Specifically, by reducing the introduced oxygen concentration c_in_O2, it is possible to further reduce the outlet oxygen concentration and increase the recovery rate. Therefore, in order to generate more nitrogen gas having higher purity, it is more preferable to use a nitrogen gas filter in which the lower the oxygen concentration of the gas to be filtered, the higher the recovery rate.

From this, the coupling system between the "fuel cell" that outputs low oxygen concentration exhaust gas and the above-mentioned "nitrogen gas filter" that uses the exhaust gas has both the outlet oxygen concentration and its recovery rate. From the viewpoint, it is also understood that the system is very compatible, that is, it is a system capable of efficiently producing nitrogen gas.

On the other hand, regarding the introduction pressure p_in of the above (b) and the outlet flow rate f_out of the above (c), the direction of increasing the recovery rate and the direction of decreasing the outlet oxygen concentration c_out_O2 (as shown in FIG. 2, for example) are In opposite directions, the recovery rate and the outlet oxygen concentration c_out_O2 are in a so-called trade-off relationship.

Therefore, for example, if the introduction pressure p_in is increased, a high-purity nitrogen gas having a lower oxygen concentration can be obtained, but on the other hand, the amount of exhaust gas required to obtain a predetermined amount of the nitrogen gas, and thus the "fuel cell" The required amount of air input to the air will increase.

Therefore, in order to secure a predetermined recovery rate while achieving the desired low outlet oxygen concentration c_out_O2 according to the performance content of the nitrogen gas output set in the nitrogen gas generation system 1 (FIG. 1), the introduction pressure p_in or It is also preferable to adjust the setting of the outlet flow rate f_out. For example, the performance content of producing high-purity nitrogen gas of a predetermined value or more (for example, 99.9 vol% or more) at a predetermined production cost (for example, equal to or less than the production cost in a PSA device as described later) is realized. Therefore, it is also preferable to determine the introduction pressure p_in and the outlet flow rate f_out (furthermore, the recovery rate depending on these) while controlling them.

Regarding the introduction pressure p_in in (b) above, the recoverability and the outlet oxygen concentration c_out_O2 have a trade-off relationship. In the nitrogen gas filter 12f of Example 1), as the introduction pressure p_in increases, the hollow fiber expands, and not only the oxygen molecule selectivity of the filter fiber but also the permeability to molecules other than oxygen molecules changes. I think it has something to do with it.

Further, regarding the recovery rate described above, the inventors of the present application have stated that the higher the temperature of the gas introduced into the nitrogen gas filter 12f, the smaller the recovery rate, and at a temperature equal to or higher than a predetermined value, the recovery rate is significantly reduced. Is confirmed. Therefore, in the temperature control U126 (FIG. 1) installed in front of the nitrogen filter U12 in the nitrogen gas generation system 1 (FIG. 1), the temperature of the exhaust gas is adjusted in consideration of ensuring a predetermined recovery rate in the nitrogen gas filter 12f. It is also preferable to carry out.

Here, regarding the influence of the temperature of the introduced gas on the recovery rate, the inventors of the present application also expand the hollow fiber of the nitrogen gas filter 12f as the temperature rises, and only the oxygen molecule selectivity of the filter fiber is selected. However, I think that it is also related to the fact that the permeability to molecules other than oxygen molecules also changes.

Examples 1 and 2 have been described above with reference to FIGS. 2 to 5, but based on the findings obtained from these experiments, the inventors of the present application have used the nitrogen gas generation system 1 to obtain 99.9 vol%. We have succeeded in producing high-purity nitrogen gas having a purity (nitrogen concentration) exceeding 0.1 vol% (1000 ppm vol) and an oxygen concentration of less than 0.1 vol% (1000 ppm vol). Such high-purity nitrogen gas can also be used in reflow soldering equipment with strict purity-related conditions. Incidentally, even in the reflow soldering apparatus, nitrogen gas having a purity (nitrogen concentration) of 99 vol% can be used depending on the type of solder paste used.

Of course, the demand for nitrogen gas is not limited to the fields of electronic devices and electric appliances that use soldering devices. In fact, the field of metals and resins that use nitrogen gas during laser processing and heat treatment, the field of transport equipment that requires nitrogen gas for tire filling and in-ship purging equipment, various process gases, pressure transport gas, and cooling. In the chemical field that uses nitrogen gas as gas, etc., in the mechanical field that requires nitrogen gas in dry cutting equipment, etc., for food storage and gas filling, and in CA (Controlled Atmosphere) storage atmosphere supply equipment and flyer equipment. Nitrogen gas is used for various purposes in various fields such as the food field where nitrogen gas is used.

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

In response to this situation, according to the Nitrogen Gas Generation System 1, for example, the introduced oxygen concentration c_in_O2, the introduced pressure p_in, and the outlet flow rate f_out were adjusted to suppress the residual oxygen to the required upper limit oxygen concentration. Nitrogen gas can be provided as appropriate. For example, in the case where the oxygen concentration may be about several vol%, the introduced oxygen concentration c_in_O2 is set to, for example, 10 vol%, the introduction pressure p_in is kept lower, the outlet flow rate f_out is made larger, and the recovery rate is increased. It is also possible to increase it.

Further, according to the present nitrogen gas generation system 1, it is possible to provide electric power and heat required at the same time according to the field and application according to the generated nitrogen gas. In this respect, it is, of course, difficult or impossible for conventional nitrogen gas generators to cover such energy supply.

Furthermore, the inventors of the present application have confirmed that the nitrogen gas generation cost can be significantly suppressed according to the nitrogen gas generation system 1 according to the present invention, based on the findings described above. For example, according to a survey by the inventors of the present application, the selling price of a nitrogen gas cylinder is, for example, ^{about 430 yen / Nm 3} , and the selling price of liquid nitrogen is, for example, about ^{120 yen / Nm 3.} Further, according to the PSA (pressure fluctuation adsorption) device, which is a widely used nitrogen gas generation device, the nitrogen gas generation cost is, for example, about ^{48 yen / Nm 3.}

On the other hand, according to the nitrogen gas generation system 1, by setting appropriate conditions including the standard output of the "fuel cell", the possible exhaust gas flow rate, and the expected hydrogen procurement cost, for example, in the PSA device as described above. It has also been confirmed by trial calculation that it is possible to realize a production cost equal to or less than the production cost. Further, as described above, in the case where the nitrogen gas generation system 1 also provides the (required) electric power and heat, the total procurement cost including these can be significantly reduced as compared with the conventional case. be.

[Other Embodiments of Nitrogen Filter U]
Hereinafter, other suitable embodiments of the nitrogen filter U12 will be described. As described above, the nitrogen filter U12 shown in FIG. 1 takes out "filter exhaust gas" containing oxygen molecules separated from nitrogen molecules (in exhaust gas) by permeating through the hollow fiber fibers of the nitrogen gas filter 12f. It has a filter purge section. Here, since the "filter exhaust gas" discharged from the filter purge section contains a considerable amount of oxygen molecules in this way, it may be used again for the fuel cell reaction or the filtering process may be performed again. Is also a possible gas.

By the way, a gas having an oxygen concentration of 10.2 vol% is introduced into the nitrogen gas filter 12f under the conditions of an introduction pressure of 6.0 atm and an outlet flow rate of 1.0 L / min, and the oxygen concentration of the filter exhaust gas discharged from the gas is examined. As a result, an experimental result of 14.9 vol% was obtained, and an experimental result of a recovery rate of 0.29 was obtained.

Here, assuming that almost all the oxygen molecules of the introduced gas (because the oxygen concentration at the outlet of the filter 12f is orders of magnitude smaller) are discharged from the filter purge portion of the nitrogen gas filter 12f, the oxygen concentration of the filter exhaust gas Is 0.102 / 0.71 = 14.4 in the calculation using the recovery rate (0.29) obtained as the above experimental result, which is almost the same as 14.9 vol% obtained as the above experimental result. Therefore, it can be seen that almost all of the oxygen gas separated as unnecessary can be recovered from the filter purge portion of the nitrogen gas filter 12f.

Therefore, in the nitrogen gas generation system 1 of the present embodiment, as shown by the “circled“ B ”” in FIG. 1, this filter exhaust gas is generated.
(A) It is sent back to the flow control U109 installed in the front stage on the air electrode side of the "fuel cell" and used again in the "fuel cell" as a gas containing oxygen and nitrogen, and / or
(B) It is sent back to the off-gas buffer tank 123 installed in front of the nitrogen filter U12, and is re-acted on the nitrogen gas filter 12f together with the exhaust gas. This makes it possible to use the oxygen gas component more effectively and to take out nitrogen gas having a lower oxygen concentration.

Here, if the filter exhaust gas whose oxygen concentration is lower than that of air is reused in the "fuel cell", the exhaust gas of this "fuel cell" can be the exhaust gas having a lower oxygen concentration. .. Further, as a result, the recovery rate of the nitrogen gas filter 12f into which such an exhaust gas is introduced is increased (as described with reference to FIG. 5), so that it is possible to finally take out more nitrogen gas. Further, although it depends on the setting of various conditions in the nitrogen gas generation system 1, by increasing the final recovery rate in the nitrogen gas filter 12f in this way, the nitrogen gas generation cost can be significantly reduced. You can.

Incidentally, as will be described in detail later with reference to FIG. 7, the oxygen concentration of the exhaust gas from the "fuel cell" is about 15 vol%, and the oxygen concentration of the filter exhaust gas is, for example, the introduced oxygen concentration c_in_O2 (as a typical value). ) Under conditions such as 1.4 times, the oxygen concentration of the filter exhaust gas is equal to or higher than that of air (20.8vol%), and as a result, the filter exhaust gas is moved to the air electrode side of the "fuel cell". It can be seen that the above-mentioned merit of remand does not occur.

On the other hand, if the oxygen concentration of the filter exhaust gas is 1.4 times the introduced oxygen concentration c_in_O2 and the oxygen concentration of the exhaust gas from the "fuel cell" is about 10 vol%, the oxygen concentration of the filter exhaust gas is about 14 vol% ( <20.8vol%), and the above-mentioned remand of filter exhaust gas is significant. Furthermore, if the oxygen concentration of the exhaust gas from the "fuel cell" is about 5 vol%, the oxygen concentration of the filter exhaust gas will be about 7 vol%, which is expected to improve the recovery rate and, depending on the system settings, nitrogen. The economic effect of significantly reducing gas production costs can also be achieved.

Hereinafter, other preferred embodiments for the reuse of the filter exhaust gas as described above will be described. FIG. 6 is a schematic diagram for explaining another embodiment of the nitrogen filter U12 according to the present invention.

According to the embodiment shown in FIG. 6A, three nitrogen gas filters 12f1, 12f2 and 12f3 are installed in the nitrogen filter U12 so as to be connected in series. Specifically, the exhaust gas taken into the nitrogen filter U12 is first introduced into the nitrogen gas filter 12f1, and the exhaust gas with an increased nitrogen concentration emitted from the nitrogen gas filter 12f1 is transferred to the next nitrogen gas filter 12f2. be introduced. Further, the exhaust gas having an increased nitrogen concentration emitted from the nitrogen gas filter 12f2 is introduced into the final nitrogen gas filter 12f3, and the nitrogen gas having a higher purity is finally taken out from the nitrogen gas filter 12f3. ..

Here, from the results of Examples 1 and 2 described above, it is understood that the nitrogen gas filter in the latter stage outputs the exhaust gas having a lower oxygen concentration with a higher recovery rate.

Further, in the present embodiment, the filter exhaust gases discharged from the nitrogen gas filters 12f1, 12f2 and 12f3 are collectively referred to as the flow control U109 (FIG. 1) in the pre-stage of the "fuel cell" and / or in the pre-stage of the nitrogen filter U12. It is sent back to the off-gas buffer tank 123 (Fig. 1) and reused. This makes it possible to use the oxygen gas component more effectively and to take out nitrogen gas having a lower oxygen concentration.

Naturally, the number of nitrogen gas filters used in this embodiment is not limited to three. Specifically, it is possible to use N nitrogen gas filters from the first nitrogen gas filter to the Nth nitrogen gas filter (N is an integer of 2 or more). in this case,
-Exhaust gas with increased nitrogen concentration is taken out from the nth (n is 1 or more and an integer up to (N-1)) nitrogen gas filter, and the taken out exhaust gas acts on the (n + 1) th filter. Then, the exhaust gas having an increased nitrogen concentration is taken out from the (n + 1) th filter.
The process of and is performed from n = 1 to (N-1).

On the other hand, according to the embodiment shown in FIG. 6B, three nitrogen gas filters 12f1, 12f2 and 12f3 are installed in the nitrogen filter U12 in a cascaded manner. Specifically, the exhaust gas taken into the nitrogen filter U12 is first introduced into the nitrogen gas filter 12f1, and the filter exhaust gas discharged from the nitrogen gas filter 12f1 is introduced into the next nitrogen gas filter 12f1. ..

Further, the filter exhaust gas discharged from the nitrogen gas filter 12f2 is introduced into the last nitrogen gas filter 12f3, and the filter exhaust gas discharged from the nitrogen gas filter 12f3 is the flow control U109 (flow control U109) in the previous stage of the "fuel cell". It is sent back to the off-gas buffer tank 123 (FIG. 1) in front of the nitrogen filter U12 and / or reused in FIG. 1) and / or.

Further, if the oxygen concentration in the filter exhaust gas discharged from the nitrogen gas filter 12f3 is equal to or higher than a predetermined value, the filter exhaust gas may be sent to an external oxygen tank for storage and storage. In any case, such treatment makes it possible to use the oxygen gas component more effectively and to take out nitrogen gas having a lower oxygen concentration.

Further, here, the exhaust gas having an increased nitrogen concentration emitted from the nitrogen gas filters 12f1, 12f2 and 12f3 is collectively output as high-purity nitrogen gas.

Since the flow rate of the gas to be introduced (introduction flow rate) decreases from the nitrogen gas filter 12f1 to 12f3, for example, the nitrogen gas filter 12f2 used is smaller than 12f1 (corresponding to a small flow rate). Further, it is also preferable to use a nitrogen gas filter 12f3 smaller than 12f2 (corresponding to a small flow rate).

Further, the number of nitrogen gas filters used in the present embodiment is naturally not limited to three. Specifically, similarly, it is possible to use N nitrogen gas filters from the first nitrogen gas filter to the Nth nitrogen gas filter (N is an integer of 2 or more).

When using N nitrogen gas filters in this way,
-From the nth (n is an integer greater than or equal to 1 and up to (N-1)) nitrogen gas filter, along with the exhaust gas with increased nitrogen concentration (or the exhaust gas from the filter with increased nitrogen concentration), another filter. The exhaust gas is taken out, the taken out filter exhaust gas is made to act on the (n + 1) th filter, and the filter exhaust gas with an increased nitrogen concentration is taken out from the (n + 1) th filter.
The process of and is performed from n = 1 to (N-1).

Here, the effect of returning the filter exhaust gas and the recovery rate in the cascade type filter system shown in FIG. 6B will be described. First, the experimental results on the oxygen concentration of the filter exhaust gas in one nitrogen gas filter 12f are shown.

FIG. 7 is a graph showing the relationship between the introduced oxygen concentration c_in_O2 in the nitrogen gas filter 12f according to the present invention and the oxygen concentration c_fout_O2 of the filter exhaust gas. Here, the graph of FIG. 7 (A) shows the result of conducting the experiment with the outlet flow rate f_out set to 2.0 L / min, while the graph of FIG. 7 (B) shows the outlet flow rate f_out of 1.0. The result of the experiment set to L / min is shown.

According to the graphs of FIGS. 7 (A) and 7 (B),
(A) The larger the introduced oxygen concentration c_in_O2, the more
(B) The smaller the introduction pressure p_in, the more
(C) The larger the outlet flow rate f_out, the more
It can be seen that the oxygen concentration c_fout_O2 of the filter exhaust gas becomes larger. Here, the calculated value of the oxygen concentration c_fout_O2 of the filter exhaust gas calculated by using the introduced flow rate f_in and the introduced oxygen concentration c_in_O2 from the measured value of the outlet flow rate f_out in (c) above is very different from the measured value of c_fout_O2 this time. It has been confirmed that they match well.

Further, between the introduced oxygen concentration c_in_O2 (vol%) in (a) above and the oxygen concentration c_fout_O2 (vol%) in the filter exhaust gas, the approximate curves shown in FIGS. 7 (A) and 7 (B) are shown. (Straight line), the following equation (5) (c_fout_O2) = b · (c_in_O2)
The relationship is established. Here, the proportional coefficient b takes a larger value as the introduction pressure p_in becomes smaller, and when the outlet flow rate f_out is 2.0 L / min, b = 1.6 to 2.1 in the graph range of FIG. 7 (A), while the outlet flow rate f_out. When is 1.0 L / min, b = 1.3 to 1.7 in the graph range of FIG. 7 (B).

In this way, under the conditions of the predetermined introduction pressure p_in and the outlet flow rate f_out, the oxygen concentration c_fout_O2 of the filter exhaust gas can increase from 1.3 times to 2.1 times the value of the introduced oxygen concentration c_in_O2. I understand.

Therefore, as a typical example, the above proportional coefficient b is set to 1.4, that is, the following equation (5') (c_fout_O2) = 1.4 · (c_in_O2)
Let us consider the effect of returning the filter exhaust gas in the cascade type filter system shown in FIG. 6 (B) above.

Returning to FIG. 6B, as shown in the figure, the oxygen concentration c_in_O2 introduced into the nitrogen gas filter 12f1 is set to C1, and the filter exhaust gas from the nitrogen gas filter 12f1 is sent to the nitrogen gas filter 12f2. The oxygen concentration c_fout_O2 of the introduced filter exhaust gas is C2, and the oxygen concentration c_fout_O2 of the filter exhaust gas introduced into the nitrogen gas filter 12f3, which is the filter exhaust gas from the nitrogen gas filter 12f2, is C3, and is from the nitrogen gas filter 12f3. Let C4 be the oxygen concentration c_fout_O2 of the filter exhaust gas of.

Here, for example, considering the case where the exhaust gas obtained by injecting air (oxygen concentration 20.8 vol%) into a "fuel cell" having an oxygen utilization rate of 50% is introduced into the nitrogen gas filter 12f1, the above equation (5) According to')
C1 = 10.4 (vol%), C2 = 14.6 (vol%), C3 = 20.4 (vol%), C4 = 28.5 (vol%)
Will be. From this result, in this case, the oxygen concentration (that is, C4) exceeds the air (20.8vol%) at the stage of the filter exhaust gas from the third nitrogen gas filter 12f3, and this gas is transferred to the "fuel cell". It can be seen that the effect of remand is not seen. Incidentally, such a filter exhaust gas may be stored and stored in another tank as a rich oxygen gas and used separately.

On the other hand, considering the case where the exhaust gas having an oxygen concentration of 5.0 vol% is introduced into the nitrogen gas filter 12f1, according to the above equation (5'),
C1 = 5.0 (vol%), C2 = 7.0 (vol%), C3 = 9.8 (vol%), C4 = 13.7 (vol%)
Will be. From this result, in this case, the oxygen concentration is less than air (20.8vol%) even at the stage of the filter exhaust gas from the third nitrogen gas filter 12f3, and this gas is returned to the "fuel cell". It is expected that the final recovery rate will be improved. Furthermore, depending on the system settings, the economic effect of significantly reducing the cost of producing nitrogen gas can also be achieved.

Next, the final recovery rate in the cascade type filter system also shown in FIG. 6 (B) will be considered.

First, as shown in FIG. 6B, the flow rate f_in introduced into the nitrogen gas filter 12f1 is f1, and the flow rate f_fout of the filter exhaust gas from the nitrogen gas filter 12f1 (and to the nitrogen gas filter 12f2). The flow rate of the filter exhaust gas from the nitrogen gas filter 12f2 is f_fout (the flow rate of introduction into the nitrogen gas filter 12f3) is f3, and the flow rate of the filter exhaust gas from the nitrogen gas filter 12f3 is f_fout. Let it be f4.

Here, in order to simplify the calculation, it is assumed that the flow rate f1 introduced into the nitrogen gas filter 12f1 is 1, and the recovery rates of the three nitrogen gas filters 12f1, 12f2 and 12f3 are all 0.3. Then, considering the above formula (5'),
f2 = 1 x (1-0.3) = 0.7, f3 = 1 x (1-0.3) ² = 0.49, f4 = 1 x (1-0.3) ³ = 0.34
Will be. From this result, the final recovery rate in the cascade type filter system shown in FIG. 6 (B) is
(6) (Recovery rate) = (1-0.34) / 1 = 0.66
Therefore, a recovery rate that greatly exceeds the recovery rate of 0.3 for each filter is realized.

The calculation result of the above equation (6) is for the case where the recovery rate of each filter is fixed at 0.3, but in reality, as described above, the introduced oxygen concentration increases from 12f1 to 12f3 of the nitrogen gas filter. c_in_O2 increases and works to reduce the recovery rate. However, on the other hand, the introduction pressure p_in becomes smaller and works in the direction of increasing the recovery rate, so in the end, the final recovery rate is not much different from the above equation (6), and at least the recovery rate of each filter is 0.3. It is considered that the value will exceed the value.

In this way, considering the recovery rate of each filter, the cascade type filter system shown in FIG. 6B is expected to improve the final recovery rate, and further, depending on the system settings, The economic effect of significantly reducing the cost of producing nitrogen gas can also be achieved.

Although various embodiments relating to the nitrogen filter U12 have been described above, also in these embodiments, the overall control U131 (FIG. 1) includes the oxygen concentration, pressure and flow rate of the exhaust gas of the "fuel cell", and further. The introduced oxygen concentration, introduction pressure, introduction flow rate, introduction gas temperature, outlet oxygen concentration, outlet pressure, outlet flow rate, etc. of each nitrogen gas filter are constantly monitored, and a predetermined amount of nitrogen gas having a predetermined high nitrogen concentration is applied in a timely manner. It is also preferred to control the individual units so that they can provide (predetermined flow).

At this time, the overall control U131 (FIG. 1) controls the oxygen concentration, pressure and flow rate of the exhaust gas of the "fuel cell", as well as the introduction oxygen concentration, introduction pressure, introduction flow rate and introduction gas temperature of each nitrogen gas filter. A known control model such as a neural network, which can estimate the optimum control value of each unit and the achievable nitrogen gas generation cost by using the measured values such as the outlet oxygen concentration, the outlet pressure, and the outlet flow rate as learning data, is known. It may be constructed using a machine learning algorithm, and control of each unit may be performed using the constructed control model.

Incidentally, the requirements of nitrogen gas users for the purity (nitrogen concentration) and production cost of nitrogen gas are diverse depending on the field and specific application, as already described. For example, some users require a purity of 99.9 vol% or higher, while others want the purity to be about 95 vol% but the production cost to be below a predetermined level. The overall control U131 (Fig. 1) is a nitrogen gas generation system that selects a control model according to such individual user requirements and uses the appropriately selected control model to achieve high performance that meets the user's requirements. It is also preferable to exert it in 1.

[Other embodiments relating to fuel cells]
FIG. 8 is a schematic diagram for explaining another embodiment of the "fuel cell" according to the present invention. It should be noted that FIGS. 8A to 8C show cross sections of each fuel cell, and linearly extending air passages and fuel passages appear in these cross sections, but these shapes are However, this is just a simple example for the explanation of the present embodiment, and the air passage and the fuel passage of the present embodiment are not limited to such a shape.

First, according to the embodiment shown in FIG. 8A, in the fuel cell 20, a plurality of battery cells such as the first cell 201, the second cell 202, ... Are stacked while being separated by a separator. ) Has the configuration. In addition, each battery cell
(A) An air passage through which air (or a gas containing nitrogen and oxygen) flows, and an air electrode whose electrode surface is exposed to the air passage.
(B) A fuel passage through which hydrogen gas, which is a fuel gas, flows, and a fuel electrode whose electrode surface is exposed to the fuel passage.
(C) It has an electrolyte provided so as to be sandwiched between the air electrode and the fuel electrode, and like a known fuel cell, the electric power generated between the air electrode and the fuel electrode by operation is externally generated. It is possible to provide to.

Here, in the fuel cell 20 of the present embodiment, in each of the battery cells of the first cell 201, the second cell 202, ..., Air and hydrogen are introduced into the battery cell from opposite sides of the battery cell. be introduced. That is, each battery cell has a configuration in which the vicinity of the outlet of the air passage and the vicinity of the inlet of the fuel passage are close to each other via the electrolyte. In the present embodiment, the flow direction of air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are consistently opposite to each other.

With the configuration described above, in the vicinity of the outlet of the air passage of each battery cell, the air that has consumed its own oxygen content by the fuel cell reaction begins to flow near the inlet of the fuel passage via the electrolyte. It will come into contact with a sufficient amount of hydrogen gas in a reactive manner. As a result, much of the small amount of oxygen remaining in the air is positively consumed by the sufficient amount of hydrogen, and finally, the air has a sufficient or considerable residual oxygen concentration. It is output as a small nitrogen gas.

That is, in the fuel cell 20 of the present embodiment, since the vicinity of the outlet of the air passage of each battery cell and the vicinity of the inlet of the fuel passage are close to each other via the electrolyte, the "altitude" is near the outlet of the air passage. An "oxygen consumption area" (FIG. 8 (A)) is formed, in which much of the residual oxygen content is used for the fuel cell reaction. As a result, it is possible to take out nitrogen gas having a sufficiently or considerably small residual oxygen concentration.

By the way, the same configuration as the above fuel cell 20 is provided not only in the solid polymer fuel cell (PEFC) and the solid oxide fuel cell (SOFC), but also in the phosphoric acid fuel cell (PAFC) and molten carbonate. It can also be realized in a salt fuel cell (MCFC) or the like.

Next, according to the embodiment shown in FIG. 8B, the fuel cells 31, 32, and 33 having a plurality of known internal structures (three in the figure) are connected in series with respect to the air passage and the fuel passage. It constitutes a fuel cell system. In particular,
(A) The air passage outlet of each battery cell (311, 312, ...) In the fuel cell 31 and the air passage inlet of each battery cell (321, 322, ...) In the fuel cell 32 are connected by piping. Connected,
(B) The air passage outlet of each battery cell (321, 322, ...) In the fuel cell 32 and the air passage inlet of each battery cell (331, 332, ...) In the fuel cell 33 are connected by piping. Connected, and more
(C) In each battery cell (331, 332, ...) Of the fuel cell 33, the fuel passage outlet on the same side as the air passage inlet and each battery cell (321, 322, ...) Of the fuel cell 32. The fuel passage inlet, which is on the same side as the air passage outlet, is connected by a pipe.
(D) In each battery cell (321, 322, ...) Of the fuel cell 32, the fuel passage outlet on the same side as the air passage inlet and each battery cell (311, 312, ...) Of the fuel cell 31. The fuel passage inlet on the same side as the air passage outlet is connected by a pipe.

In the present embodiment, under such a configuration, air (or a mixed gas of nitrogen and oxygen) is introduced from the air passage inlet of each battery cell in the fuel cell 31, while hydrogen is on the opposite side of the fuel cell. It is introduced from the fuel passage inlet of each battery cell in 33. As a result, in each fuel cell, the flow direction of air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are opposite to each other, and each battery cell of the fuel cell 33 near the final outlet for air. The air passage) and the vicinity of the initial inlet for hydrogen (the fuel passage of each battery cell of the fuel cell 33) are configured to be close to each other via an electrolyte.

Further, with such a configuration, in the air passage of each battery cell in the fuel cell 33 (which is near the final outlet for air), the air that has consumed its own oxygen content by the fuel cell reaction up to that point is in each of the fuel cell 33. It will come into contact with a sufficient amount of hydrogen gas that has just begun to flow through the fuel cell's fuel cell in a reactive manner via an electrolyte. As a result, much of the small amount of oxygen remaining in the air is positively consumed by the sufficient amount of hydrogen, and finally, the air has a sufficient or considerable residual oxygen concentration. It is output as a small nitrogen gas.

Incidentally, the fuel cells 31 to 33 constituting the above fuel cell system may be not only PEFC and SOFC but also PAFC, MCFC and the like. Further, the number of fuel cells constituting the fuel cell system is not limited to three, of course, and may be two or four or more.

Next, according to the embodiment shown in FIG. 8C, the cylindrical stack type fuel cell 40 has a configuration in which a plurality of cylindrical cells 401 are stacked in a form in which the cell axes are aligned in parallel with each other. Have. In addition, each cylindrical cell 401 is
(A) An air passage through which air (or a gas containing nitrogen and oxygen) flows, and a cylindrical air electrode that surrounds the air passage on its inner surface side.
(C) A cylindrical electrolyte that wraps around the outside of the cylindrical air electrode, and
(B) It has a cylindrical fuel electrode that further wraps the outside of the electrolytic electrolyte, and a fuel path through which hydrogen gas, which is a fuel gas, surrounds the outer surface side of the fuel electrode, and is known. Similar to a fuel cell, it is possible to provide the electric power generated between the air electrode and the fuel electrode to the outside by operating.

Here, in the cylindrical stack type fuel cell 40 of the present embodiment, in each battery cell 401, air and hydrogen are introduced into the battery cell 401 from opposite sides of the battery cell 401. That is, each battery cell 401 has a configuration in which the vicinity of the outlet of the air passage and the vicinity of the inlet of the fuel passage are close to each other via the electrolyte. In the present embodiment, the flow direction of air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are consistently opposite to each other.

With such a configuration, in the vicinity of the outlet of the air passage of each battery cell 401, the air that has consumed its own oxygen content by the fuel cell reaction to that point passes through the electrolyte that surrounds itself, and further outside the fuel passage. It will come into contact with a sufficient amount of hydrogen gas that has begun to flow near the inlet in a reactive manner. As a result, much of the small amount of oxygen remaining in the air is positively consumed by the sufficient amount of hydrogen, and finally, the air has a sufficient or considerable residual oxygen concentration. It is output as a small nitrogen gas.

That is, in the cylindrical stack type fuel cell 40 of the present embodiment, the vicinity of the outlet of the air passage and the vicinity of the inlet of the fuel passage of each battery cell 401 are close to each other via the electrolyte, and therefore, the vicinity of the outlet of the air passage. In addition, a "high oxygen consumption area" (FIG. 8C) is formed, in which most of the residual oxygen content is used for the fuel cell reaction. As a result, it is possible to take out nitrogen gas having a sufficiently or considerably small residual oxygen concentration.

Incidentally, the same configuration as the above-mentioned cylindrical stack type fuel cell 40 can be realized not only in SOFC but also in PEFC, PAFC, MCFC and the like.

FIG. 9 is a schematic diagram for explaining still another embodiment of the "fuel cell" according to the present invention. The cross sections of the fuel cells are also shown in FIGS. 9A to 9C, and linearly extending air passages and fuel passages appear in the cross sections, but these shapes are However, this is just a simple example for the explanation of the present embodiment, and the air passage and the fuel passage of the present embodiment are not limited to such a shape.

First, according to the embodiment shown in FIG. 9A, the solid oxide fuel cell and the solid polymer fuel cell SOFC51 and PEFC52 are connected in series with respect to the air passage and the fuel passage, respectively. It constitutes a fuel cell system. In particular,
(A) The air passage outlet of each battery cell (511, 512, ...) In the SOFC 51 and the air passage inlet of each battery cell (521, 522, ...) In the PEFC 52 are connected by a pipe.
(B) The fuel passage outlet on the same side as the air passage inlet in each battery cell (521, 522, ...) Of PEFC52 and the air passage in each battery cell (511,512, ...) Of SOFC51. The fuel passage inlet on the same side as the outlet is connected by piping.

In the present embodiment, under such a configuration, air (or a gas containing nitrogen and oxygen) is introduced from the air passage inlet of each battery cell in SOFC 51, while hydrogen is introduced in PEFC 52 on the opposite side thereof. It is introduced from the fuel passage inlet of the battery cell. As a result, the flow direction of air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are opposite to each other, and near the final outlet for air (the air passage of each battery cell of PEFC 52) and hydrogen. The vicinity of the entrance of the PEFC 52 at the time of introduction (the fuel passage of each battery cell of the PEFC 52) is configured to be close to each other via an electrolyte.

Further, with such a configuration, in the air passage of each battery cell in the PEFC 52 (near the final outlet for air), the air that has consumed its own oxygen content by the fuel cell reaction to that extent is the fuel of each battery cell in the PEFC 52. It will come into contact with a sufficient amount of hydrogen gas that has just begun to flow through the path in a reactive manner via an electrolyte. As a result, much of the small amount of oxygen remaining in the air is positively consumed by the sufficient amount of hydrogen, and finally, the air has a sufficient or considerable residual oxygen concentration. It is output as a small nitrogen gas.

Further, the connection system between the SOFC 51 and the PEFC 52 described above suppresses the deterioration of the electrolyte in each fuel cell. Specifically, the electrolyte of PEFC52 is a solid polymer membrane formed of a fluorine-based polymer or the like, but since a sufficient amount of hydrogen is secured in PEFC52, hydrogen ions are deficient in this solid polymer membrane. There is nothing to do. As a result, it is possible to avoid a situation in which hydrogen atoms of the polymer in the solid polymer film are taken into the fuel cell reaction and deteriorate the solid polymer film.

On the other hand, the electrolyte of SOFC51 is a solid oxide film formed of stabilized zirconia, various perovskite oxides, etc. However, since a sufficient amount of oxygen is secured in SOFC51, oxides are formed in this solid oxide film. There is no ion deficiency. As a result, the solid oxide film is exposed to a strong reducing atmosphere (high temperature of 700 to 800 ° C.), and oxygen atoms in the solid oxide film are incorporated into the fuel cell reaction to reduce and deteriorate the solid oxide film. It is possible to avoid the situation where it ends up.

Further, as one preferred embodiment, the SOFC 51 and the PEFC 52 are fuel cells having the same efficiency, and the consumption of oxygen in the air and the consumption of oxygen in the air at the connection point between the SOFC 51 and the PEFC 52, that is, the piping position connecting the two. It is also preferable to set the consumption amount of hydrogen in the hydrogen gas to be substantially the same.

Further, it is also preferable that a heat exchanger is connected to the air passage outlet of each battery cell in the SOFC 51, and heat is recovered from the high temperature exhaust gas emitted from the air passage outlet by this heat exchanger. It is also preferable to install a corrosive gas removal unit using an activated carbon filter or the like after the heat exchanger. Further, it is also preferable to install a unit having a dehumidifying function such as an auto drain or a dehumidifier at the outlet of each battery cell in the PEFC 52, particularly at the outlet of the fuel passage.

Next, according to the embodiment shown in FIG. 9B, the fuel cell 61 and the fuel cell 62, both of which have a known internal structure, are connected in series with respect to the air passage to form a fuel cell system. There is. In particular,
(A) The air passage outlet of each battery cell (611, 612, ...) In the fuel cell 61 and the air passage inlet of each battery cell (621, 622, ...) In the fuel cell 62 are connected to each other. Connected by
(B) In each battery cell (621, 622, ...) Of the fuel cell 62, the fuel passage outlet on the same side as the air passage inlet and each battery cell (611, 612, ...) Of the fuel cell 61. The fuel passage inlet on the same side as the air passage inlet is connected by a pipe.

In this embodiment, under such a configuration, air (or a gas containing nitrogen and oxygen) is introduced from the air passage inlet of each battery cell in the fuel cell 61, while hydrogen is the fuel on the opposite side. It is introduced from the fuel passage inlet of each battery cell in the battery 62. As a result, the vicinity of the final outlet for air (the air passage of each battery cell of the fuel cell 62) and the vicinity of the initial inlet for hydrogen (the fuel cell of each battery cell of the fuel cell 62) become It is configured to be close to each other via an electrolyte.

Incidentally, in the present embodiment, in each battery cell of the fuel cell 61, the flow direction of air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are the same, but in each battery cell of the fuel cell 62, the flow direction is the same. The opposite of each other.

Further, according to the configuration as described above, in the air passage of each battery cell in the fuel cell 62 (which is near the final outlet for air), the air that has consumed its own oxygen content by the fuel cell reaction up to that point is fuel. It comes into contact with a sufficient amount of hydrogen gas that has just begun to flow through the fuel cell of each battery cell in the battery 62 in a reactive manner via an electrolyte. As a result, much of the small amount of oxygen remaining in the air is positively consumed by the sufficient amount of hydrogen, and finally, the air has a sufficient or considerable residual oxygen concentration. It is output as a small nitrogen gas.

Incidentally, the fuel cells 61 and 62 constituting the above fuel cell system may be not only PEFC and SOFC but also PAFC, MCFC and the like. Here, in the fuel cell 61, although the flow direction of the air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are the same, the residual amount of hydrogen gas is small, so that the fuel cell 61 has a small amount. In order to avoid the situation where the solid polymer film is deteriorated, it is also preferable not to use PEFC. On the other hand, it is also preferable that the fuel cell 62 is not SOFC in order to avoid a situation in which the solid oxide film (as described above) is reduced or deteriorated.

Next, according to the embodiment shown in FIG. 9C, the fuel cell 71 and the fuel cell 72, both having a known internal structure, are connected in series with respect to the air passage and in parallel with respect to the fuel passage. , Consists of the fuel cell system. In particular,
(A) The air passage outlet of each battery cell (711, 712, ...) In the fuel cell 71 and the air passage inlet of each battery cell (721, 722, ...) In the fuel cell 72 are connected to each other. Connected by
(B) In each battery cell (711, 712, ...) Of the fuel cell 71, the fuel passage inlet on the same side as the air passage inlet and each battery cell (721, 722, ...) Of the fuel cell 72. The fuel passage inlet on the same side as the air passage outlet in the above is connected in parallel with the pipe from the hydrogen supply source.

In the present embodiment, under such a configuration, air (or a mixed gas of nitrogen and oxygen) is introduced from the air passage inlet of each battery cell in the fuel cell 71, while hydrogen is introduced into the pipe of the above (b). Therefore, it is introduced into each fuel cell (71, 72). As a result, the vicinity of the final outlet for air (the air passage of each battery cell of the fuel cell 72) and the vicinity of the initial inlet for hydrogen (the fuel passage of each battery cell of the fuel cell 72) become It is configured to be close to each other via an electrolyte.

Incidentally, also in this embodiment, as in the above-described embodiment (B), in each battery cell of the fuel cell 71, the flow direction of air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are the same. However, in each battery cell of the fuel cell 72, they are opposite to each other.

Further, according to the configuration as described above, in the air passage of each battery cell in the fuel cell 72 (which is near the final outlet for air), the air that has consumed its own oxygen content by the fuel cell reaction up to that point is fuel. It comes into contact with a sufficient amount of hydrogen gas that has just begun to flow through the fuel cell of each battery cell in the battery 72 in a reactive manner via an electrolyte. As a result, much of the small amount of oxygen remaining in the air is positively consumed by the sufficient amount of hydrogen, and finally, the air has a sufficient or considerable residual oxygen concentration. It is output as a small nitrogen gas.

Incidentally, the fuel cells 71 and 72 constituting the above fuel cell system may be not only PEFC and SOFC but also PAFC, MCFC and the like. Here, in the fuel cell 71, air and hydrogen are introduced from the same side of the fuel cell 71, and the flow direction of the air flowing through the air passage and the flow direction of hydrogen flowing through the fuel passage are the same. , It is the same as a normal fuel cell. Therefore, the fuel cell 71 may be of any of the above types. On the other hand, it is also preferable that the fuel cell 72 is not SOFC in order to avoid a situation in which the solid oxide film (as described above) is reduced or deteriorated.

As described above, using FIGS. 8 (A) to 8 (C) and FIGS. 9 (A) to 9 (C), the fuel cell 20, the fuel cell system of the fuel cells 31 to 33, the cylindrical stack type fuel cell 40, the SOFC 51, and the PEFC 52. The fuel cell system, the fuel cell system of the fuel cells 61 and 62, and the fuel cell system of the fuel cells 71 and 72 have been described. Here, these fuel cells (systems) may be used as components of the fuel cell U11 in the nitrogen gas generation system 1 shown in FIG. 1 and contribute to the generation of nitrogen gas having a lower oxygen concentration. good. Of course, it can also be used as a component of the fuel cell U11 in the nitrogen gas generation system 1 that employs the combustion catalyst U90 (FIG. 11) described later.

Alternatively, these fuel cells (systems) may be used as a main component in an apparatus that produces high-purity nitrogen gas or exhaust gas (nitrogen gas) having a low oxygen concentration without depending on a nitrogen gas filter. That is, for example, it is possible to efficiently generate nitrogen gas having a lower oxygen concentration only with these fuel cells (systems) without using the nitrogen filter U12 (FIG. 1).
[Possible invention claims]
For a fuel cell capable of causing a fuel cell reaction by bringing an oxygen-containing gas supplied into the battery and undergoing a fuel cell reaction and the initial fuel gas supplied into the battery close to each other via an electrolyte. , Air, or a gas containing nitrogen and oxygen to operate the fuel cell, and the air or the gas having a lower oxygen concentration is taken out from the fuel cell.
[Possible invention claims]
For a fuel cell capable of causing a fuel cell reaction by bringing an oxygen-containing gas supplied into the battery and undergoing a fuel cell reaction and the initial fuel gas supplied into the battery close to each other via an electrolyte. , A method for generating a low oxygen concentration gas, which comprises supplying a gas containing oxygen to operate the fuel cell, and extracting the gas having a lower oxygen concentration from the fuel cell.

FIG. 10 is a schematic diagram for explaining further other embodiments of the nitrogen gas generation system according to the present invention.

In the embodiment shown in FIG. 10, in the nitrogen gas generation system 1 shown in FIG. 1, a new fuel cell U80 different from the fuel cell U11 is provided in the subsequent stage of the nitrogen filter U12 (for example, immediately after the flow control U127). Has been done.

Here, the "fuel cell" of the fuel cell U80 and the "fuel cell" of the fuel cell U11 roughly correspond to (or correspond to) the fuel cell 61 and the fuel cell 62 shown in FIG. 9B, respectively. It has become. That is, as already explained in detail, in the "fuel cell" of the fuel cell U80, the vicinity of the final outlet for air (the air passage of each battery cell of the "fuel cell") and the initial introduction for hydrogen. The vicinity of the inlet (the fuel path of each battery cell of the "fuel cell") is configured to be close to each other via an electrolyte.

Specifically, the "fuel cell" of the fuel cell U80 is an air passage inlet (on the air electrode side) of a low oxygen concentration (for example, an oxygen concentration of 0.1 to several vol%) taken out from the nitrogen filter U12. In addition, hydrogen is introduced from the fuel passage inlet (on the fuel electrode side) opposite to the air passage inlet to cause a fuel cell reaction, and most of the residual oxygen content in the nitrogen gas taken in is sufficient. It is actively consumed by a large amount of hydrogen, and finally, a high-purity nitrogen gas having a sufficiently low residual oxygen concentration (for example, an oxygen concentration of less than 0.1 vol%) is output.

Here, the high-purity nitrogen gas is temporarily stored and stored in the nitrogen tank 129 (FIG. 1) via the drain 802, the gas-liquid separation U, the oxygen concentration meter, the flow meter, and the pressure boosting U128 (FIG. 1). It is also preferable that it is appropriately provided to the outside.

Further, the hydrogen gas (including a considerable amount of residual hydrogen) taken out from the fuel passage outlet on the same side as the air passage inlet in the "fuel cell" of the fuel cell U80 is drain 801, gas-liquid separation U803, and check valve. , And sent to the hydrogen recovery U115 via the flow control U804, and is put into the "fuel cell" from the fuel passage inlet (on the hydrogen electrode side) of the "fuel cell" of the fuel cell U11, and is subjected to the fuel cell reaction again. It is used.

Incidentally, in the present embodiment, the "fuel cell" of the fuel cell U11 and the "fuel cell" of the fuel cell U80 are both preferably PEFC, and may be SOFC and PEFC, respectively. In any case, the problem of electrolyte deterioration as described above can be avoided.

Further, in the nitrogen gas generation system of the embodiment shown in FIG. 10, it is possible to generate nitrogen gas having a lower oxygen concentration only by the fuel cells U11 and 80 without using the nitrogen filter U12.

[Other embodiments using a combustion catalyst]
FIG. 11 is a schematic diagram for explaining further other embodiments of the nitrogen gas generation system according to the present invention.

In the embodiment shown in FIG. 11, in the nitrogen gas generation system 1 shown in FIG. 1, the combustion catalyst U90 is provided in the subsequent stage of the nitrogen filter U12 (for example, immediately after the flow control U127). Here, the combustion catalyst U90 combines hydrogen gas and oxygen content in exhaust gas on a solid catalyst composed of a noble metal-based compound such as palladium (Pd) or platinum (Pt), or another transition metal-based compound. It is a unit that makes contact and performs catalytic combustion, which is a controlled oxidation reaction rather than flame combustion.

Specifically, in the present embodiment, the combustion catalyst U90 is
(A) Nitrogen gas with a low oxygen concentration (for example, an oxygen concentration of 0.1 to several vol%) taken out from the nitrogen filter U12, and
(B) Hydrogen gas taken out from the fuel passage outlet of the fuel cell U11, passed through the drain 111, the pressure control U113, and the gas-liquid separation U114, and then recovered by the hydrogen recovery U115, and then the flow control U902 and the non-stop. It takes in hydrogen gas sent through the valve and brings them into contact with each other on a "solid catalyst" installed in the unit to cause a catalytic combustion reaction, and finally the residual oxygen concentration is sufficiently small ( For example, it outputs nitrogen gas (with an oxygen concentration of 0.01 vol% (100 ppm vol) order). Of course, instead of the hydrogen gas described in (b) above, hydrogen gas can be supplied to the combustion catalyst U90 from, for example, hydrogen generation U102 or hydrogen generation reforming U103.

Here, the "solid catalyst" installed in the combustion catalyst U90 is a ceramic having many fine holes and supporting a catalyst such as platinum (Pt) or palladium (Pd) on the surface including the inside of the holes. It is also preferable to use a honeycomb. In this case, the total area of the catalyst surface, which is the field of the catalyst combustion reaction, can be made sufficiently large, and efficient catalyst combustion can be carried out.

Further, the nitrogen gas having an extremely low oxygen concentration output from the combustion catalyst U90 comes out in a high temperature state, but the heat may be recovered by the heat exchanger 901 installed at the outlet of the combustion catalyst U90. In this case, the heat recovered by the heat exchanger 901 is supplied to the off-gas buffer tank 123 and the exhaust gas supplied to the nitrogen filter U12 at a higher temperature (for example, 45 ° C.), similarly to the heat recovered from the fuel cell U11. It is also preferable that it is used for making or supplied to the outside. When the temperature of the nitrogen gas output from the combustion catalyst U90 is not so high, the nitrogen gas may be sent to the hydrogen filter U903 described later without passing through the heat exchanger 901.

Here, the nitrogen gas having an extremely low oxygen concentration output from the combustion catalyst U90 usually includes residual hydrogen gas that has not been burned in the catalyst combustion reaction. In the present embodiment, the hydrogen filter U903 takes in the high-purity nitrogen gas that has passed through the heat exchange U901, and the residual hydrogen gas is separated from the nitrogen gas having an extremely low oxygen concentration by a known hydrogen gas filter installed inside. And output higher purity nitrogen gas. The output high-purity nitrogen gas is then stored and stored in the nitrogen tank 129 (Fig. 1) via a check valve, an oxygen concentration meter, a flow meter, and a pressure boosting U128 (Fig. 1), and is appropriately externally stored. It is also preferable to be provided in.

Incidentally, as the above-mentioned hydrogen gas filter, for example, a filter provided with a palladium (Pd) -based hydrogen permeation membrane can be used, but a hydrogen gas filter provided with an aromatic polyimide-based gas separation membrane may be adopted. .. For example, UBE GAS SEPARATOR manufactured by Ube Industries, which uses a pipe in which hollow filamentous membranes are bundled, and SEPURUN Noble manufactured by EVONIC can be adopted.

Further, in the present embodiment, the hydrogen gas separated from the nitrogen gas by the hydrogen filter U903 is sent to the hydrogen recovery U115 via the flow control U904 and used again in the fuel cell U11 or again in the combustion catalyst U90. It can be used for catalytic combustion.

Further, as a preferred embodiment, by adopting the combustion catalyst U90 in the nitrogen gas generation system 1 (FIG. 1) as described above, the recovery rate of the nitrogen filter U12 in the nitrogen gas filter 12f (FIG. 1) is improved. It is also possible. That is, based on the fact that the combustion catalyst U90 finally makes the oxygen concentration extremely low, for example, if the oxygen concentration of the gas output from the nitrogen gas filter 12f is set to be several vol%, the nitrogen gas filter 12f can be used. Can introduce a considerably large flow rate (outlet flow rate) of exhaust gas (as can be seen from the graph of FIG. 2). As a result, the recovery rate of the nitrogen gas filter 12f can be increased (as can be seen from the graph of FIG. 5). Furthermore, if a cascade type filter system as shown in FIG. 6 (B) is adopted as the nitrogen gas filter of the nitrogen filter U12, it is possible to achieve a recovery rate of nearly 1.0 (100%) depending on the design. It becomes.

Further, in the nitrogen gas generation system of the embodiment shown in FIG. 11, it is also possible to efficiently generate nitrogen gas having a lower oxygen concentration only by the fuel cell U11 and the combustion catalyst U90 without using the nitrogen filter U12. It becomes. In any case, the coupling system between the "fuel cell" and the "combustion catalyst" is very compatible in that it can share the required hydrogen gas, and it is a system that can efficiently generate nitrogen gas. It is understood that
[Possible invention claims]
Air or a gas containing nitrogen and oxygen and a fuel gas are supplied to the fuel cell to operate the fuel cell.
Exhaust gas having an oxygen concentration lower than that of air is extracted from the fuel cell.
A method for producing nitrogen gas, which comprises reacting the extracted exhaust gas with the fuel gas on a combustion catalyst to make the exhaust gas into an exhaust gas having a lower oxygen concentration.

[Fuel cell characteristics]
FIG. 12 is a graph showing the relationship between the current and the voltage in the “fuel cell” in one embodiment in which the driving state of the “fuel cell” according to the present invention is investigated.

Here, in this embodiment, a JARI type PEFC is used as the "fuel cell" of the fuel cell U11, the cell temperature of the "fuel cell" being driven is 80 ° C., and the back pressure of the "fuel cell", that is, When the pressures of air and hydrogen introduced into the "fuel cell" are 4.0 atm, 5.0 atm, 6.0 atm and 7.0 atm, the current flowing between the air electrode and the fuel electrode of the "fuel cell" and the air electrode And the voltage between the fuel electrode and the fuel electrode are measured. The resistance value of the external resistor connected as a load between the two electrodes is 0.075Ω.

According to the graph of FIG. 12, the voltage of the "fuel cell" decreases as the current increases, but the degree of decrease (slope of the graph line) becomes more gradual as the pressure of the introduced air and hydrogen increases. Become. As described above, in the "fuel cell", in a state of higher pressure, even if the fuel cell reaction proceeds and the current increases, the voltage does not decrease so much and is maintained at a higher value.

Therefore, it is understood that the higher the pressure of air and hydrogen introduced into the "fuel cell", the more stable the voltage of electric power can be provided.

FIG. 13 is a graph showing the relationship between the cell temperature and the electric power in the “fuel cell” in one embodiment in which the driving state of the “fuel cell” according to the present invention is investigated.

Here, the experimental conditions in this example are the same as those in the example described with reference to FIG. 12 except for the cell temperature, and the cell temperature is changed from about 45 ° C. to about 80 ° C., and the normalized power at that time is changed. Is being measured. In addition, this standardized power is each pressure (4.0 atm), where the power value (= voltage value x current value) on the low temperature side of the graph when the pressure of the introduced air and hydrogen is atmospheric pressure (1 atm) is 1. , 5.0 atm, 6.0 atm, 7.0 atm).

According to the graph of FIG. 13, when the pressure of the introduced air and hydrogen is 4.0 atm, the standardized power of the “fuel cell” tends to decrease as the cell temperature increases, but the larger the pressure, the more. , The tendency of the decrease becomes smaller. Further, when the pressures of the introduced air and hydrogen are 6.0 atm and 7.0 atm, the normalized power becomes almost constant regardless of the cell temperature.

Therefore, it is understood that the higher the pressure of air and hydrogen introduced into the "fuel cell", the more stable electric power can be provided with less fluctuation due to cell temperature.

FIG. 14 is a graph showing the relationship between the cell temperature of the “fuel cell” and the relative humidity of the exhaust gas in one embodiment in which the driving state of the “fuel cell” according to the present invention is investigated.

Here, the experimental conditions in this embodiment are substantially the same as those in the embodiment described with reference to FIG. 13, and the cell temperature is changed from 35 ° C. to 80 ° C., and the cell temperature is changed from 35 ° C. to 80 ° C. The relative humidity of the exhaust gas after passing through the drain 112 (FIG. 1) is measured. Incidentally, this relative humidity is measured by taking out the exhaust gas that has passed through the drain 112, storing it in a measuring container, and then using a thermohygrometer.

According to the graph of FIG. 14, the relative humidity of the exhaust gas passing through the drain 112 is 80% in the range of the cell temperature from 35 ° C. to 80 ° C. when the pressure of the introduced air and hydrogen is atmospheric pressure (1.0 atm). However, when the pressure is 3.0 atm and 5.0 atm, it decreases to about 30% and about 20%, respectively. It is considered that such a result is because the higher the pressure of the introduced air and hydrogen, the higher the dew point of the exhaust gas at the drain 112, and the more water and water vapor in the exhaust gas are condensed and removed.

Therefore, it is understood that the higher the pressure of air and hydrogen introduced into the "fuel cell", the drier (less water and water vapor content) exhaust gas can be obtained.

As described in detail above, according to the present invention, it is possible to efficiently generate high-purity nitrogen gas by using a fuel cell. In particular, if a nitrogen gas filter or a combustion catalyst is used, it is possible to generate nitrogen gas having a higher purity.

Moreover, when the hydrogen gas society arrives in the future, the utilization of fuel cells that use hydrogen gas as a fuel gas is expected to become widespread everywhere. The present invention will greatly contribute to the efficient production of nitrogen gas in such an era. Of course, it is also possible to meet the needs of supplying electricity and heat on the spot. That is, it is considered that the present invention greatly contributes to the construction of an energy / product supply and demand system for local production for local consumption, which is considered to be one ideal form in the future.

Further, although it is only one embodiment of the present invention, in the present invention, hydrogen gas is supplied as a fuel gas to a fuel cell having a high back pressure setting by using a hydrogen generation U provided with an electrolysis unit. Is also possible. Such a configuration is also considered to be greatly utilized in the hydrogen gas society described above.

It should be noted that all of the embodiments described above are exemplary and not limited to the present invention, and the present invention can be carried out in various other modifications and modifications. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

1 Nitrogen gas generation system / equipment 101 Renewable energy power generation unit (U)
101s storage U
102 Hydrogen generation U
103 Hydrogen production reforming U
104 Hydrogen tank 105, 109, 127, 804, 902, 904 Flow control U
106 Air compression U
107 Air tank 108 Filter U
11,80 Fuel cell U
111, 112, 801, 802 Drain 113, 121 Pressure control U
114, 122, 803 Vapor-liquid separation U
115 Hydrogen recovery U
12 Nitrogen filter U
12f, 12f1, 12f2, 12f3 Nitrogen gas filter 123 Off-gas buffer tank 124, 128 Pressure boost U
125 Removal of corrosive gas, etc. U
126 Temperature control U
129 Nitrogen tank 131 Overall control U
20, 31, 32, 33, 61, 62, 71, 72 Fuel cells 201, 311, 321, 331, 511, 521, 611, 621, 711, 721 First cell 202, 312, 322, 332, 512, 522 , 612, 622, 712, 722 Second cell 40 Cylindrical stack fuel cell 401 Cylindrical cell 51 SOFC
52 PEFC
90 Combustion catalyst U
901 Heat Exchange U
903 Hydrogen filter U

Claims (15)

Air or a gas containing nitrogen and oxygen and a fuel gas are supplied to the fuel cell to operate the fuel cell.
Exhaust gas having an oxygen concentration lower than that of air is extracted from the fuel cell.
A method for producing nitrogen gas, which comprises allowing the exhaust gas to act on a filter using fibers having different degrees of permeation for nitrogen and oxygen, and extracting the exhaust gas having an increased nitrogen concentration from the filter. The air or the gas having a pressure exceeding the atmospheric pressure and the fuel gas having a pressure exceeding the atmospheric pressure are supplied to the fuel cell, and the air having a pressure exceeding the atmospheric pressure is supplied from the fuel cell. Take out the exhaust gas with a lower oxygen concentration than
The nitrogen gas generation method according to claim 1, wherein the exhaust gas acts on the filter at a pressure exceeding atmospheric pressure. The nitrogen gas generation method according to claim 1 or 2, wherein the exhaust gas taken out from the fuel cell is further increased in pressure by using a pressure increasing means and then acted on the filter. The pressure of the exhaust gas acting on the filter is a pressure threshold value determined by the filter, which exceeds the pressure threshold value which becomes larger as the flow rate of the exhaust gas when taken out from the filter increases. The method for producing nitrogen gas according to any one of claims 1 to 3, wherein the pressure is used. The nitrogen gas generation method according to any one of claims 1 to 4, wherein as the filter on which the exhaust gas acts, a filter whose recovery rate increases as the oxygen concentration of the gas to be filtered decreases. Exhaust gas having an oxygen concentration of 2.5% by volume or less is allowed to act on the filter, and the exhaust gas having an oxygen concentration of 1/10 or less of the result of applying air is taken out from the filter. The nitrogen gas generation method according to any one of claims 1 to 5, wherein the nitrogen gas is generated. From the filter on which the exhaust gas is allowed to act, a filter exhaust gas containing a gas that has permeated the fiber and is different from the exhaust gas having an increased nitrogen concentration is taken out.
From claim 1, the extracted filter exhaust gas is used as a part of the gas supplied to the fuel cell and / or is used in addition to the exhaust gas acting on the filter. The nitrogen gas generation method according to any one of 6. From the filter on which the exhaust gas is allowed to act, a filter exhaust gas containing a gas that has permeated the fiber and is different from the exhaust gas having an increased nitrogen concentration is taken out.
The filter relates to N filters from the first filter using the fiber which permeates more oxygen than nitrogen to the Nth filter (N is an integer of 2 or more), using the filter as the first filter. In the treatment, from the nth filter (n is 1 or more and an integer up to (N-1)), the exhaust gas having an increased nitrogen concentration or the exhaust gas from the filter having an increased nitrogen concentration is separated from the filter. The filter exhaust gas is taken out, the taken out filter exhaust gas is allowed to act on the (n + 1) th filter, and the filter exhaust gas with an increased nitrogen concentration is taken out from the (n + 1) th filter. The nitrogen gas generation method according to any one of claims 1 to 7, wherein the method is carried out. The filter relates to N filters from the first filter using the fiber that permeates more oxygen than nitrogen to the Nth filter (N is an integer of 2 or more), using the filter as the first filter. In the treatment, the exhaust gas having an increased nitrogen concentration is taken out from the nth filter (n is 1 or more and an integer up to (N-1)), and the taken out exhaust gas is used as the (n + 1) th filter. The nitrogen gas generation according to any one of claims 1 to 7, wherein the treatment is carried out in which the exhaust gas having an increased nitrogen concentration is taken out from the (n + 1) th filter. Method. The exhaust gas taken out from the fuel cell is treated to remove or reduce at least one of sulfide, chloride, hydrocarbon, fluoride and a strong alkaline compound, and then the exhaust gas is applied to the filter. The method for producing a nitrogen gas according to any one of claims 1 to 9, wherein the method is allowed to act. The temperature of the exhaust gas taken out from the fuel cell is adjusted by using a temperature adjusting means capable of bringing the temperature of the introduced gas close to a suitable temperature set based on the characteristics of the filter, and then the exhaust gas is used. The method for producing nitrogen gas according to any one of claims 1 to 10, wherein the method acts on a filter. The exhaust gas extracted from the filter is used as an electrolyte in another fuel cell, which is a gas containing oxygen that has been supplied into the battery and undergoes a fuel cell reaction, and the initial fuel gas supplied into the battery. By supplying fuel to another fuel cell capable of causing a fuel cell reaction in the vicinity through the fuel cell, the other fuel cell is operated, and the exhaust gas having a lower oxygen concentration is extracted from the other fuel cell. The nitrogen gas generation method according to any one of claims 1 to 11, which is characterized. Any one of claims 1 to 11, wherein the exhaust gas taken out from the filter and the fuel gas are reacted on a combustion catalyst to obtain the exhaust gas having a lower oxygen concentration. The method for producing nitrogen gas according to the section. In the fuel cell, the air or the gas supplied into the battery and undergoing the fuel cell reaction and the initial fuel gas supplied into the battery are brought close to each other via an electrolyte to cause a fuel cell reaction. The method for producing a nitrogen gas according to any one of claims 1 to 13, wherein the fuel cell is capable of producing a fuel cell. With fuel cells
Filters using fibers with different degrees of permeation for nitrogen and oxygen,
A pressure control means capable of supplying air having a pressure exceeding atmospheric pressure, a gas containing nitrogen and oxygen having a pressure exceeding atmospheric pressure, and a fuel gas having a pressure exceeding atmospheric pressure to the fuel cell.
Exhaust gas discharged from the operating fuel cell, which has a pressure exceeding atmospheric pressure and has an oxygen concentration lower than that of air, is introduced to act on the filter, and the exhaust gas having an increased nitrogen concentration from the filter is introduced. A nitrogen gas generator characterized by having a filter input / output unit for taking out a fuel.

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