JP6932325B2 - High-concentration nitrogen gas generation system and high-concentration nitrogen gas generation method - Google Patents

Description

The present invention relates to a high concentration nitrogen gas generation system and a method for executing the system, and more particularly to a system and a method for generating a high concentration nitrogen gas from the air exhausted from a fuel cell.

Nitrogen (nitrogen gas) utilizes its inert physical characteristics to improve safety such as safety and purging, and to maintain quality such as antioxidants, from semiconductor manufacturing processes to petrochemicals and food / beverage manufacturing. It is used in a wide range of fields. Nitrogen gas for industrial use is required to have a nitrogen concentration of about 95% or more. Further, it is convenient that the pressure is applied when the product is used for each purpose.

By the way, about 99% of air is composed of oxygen and nitrogen, and the ratio is about 2 (oxygen): 8 (nitrogen), so nitrogen gas separates oxygen, which occupies about 20%, from the air. It can be obtained by removing it. There are mainly a membrane separation method and a PSA (pressure fluctuation adsorption) method as methods for generating such nitrogen gas in the vicinity of the place of demand. Since both methods produce nitrogen gas from compressed air, they are added at the time of becoming nitrogen gas. There is an advantage of being pressured.

The membrane separation method is a method using a special hollow fiber membrane, in which compressed air is permeated through the hollow fiber membrane, and oxygen is preferentially separated and removed due to the difference in the permeation rate of each component. , It is possible to extract nitrogen gas having a concentration of about 97% to 99%.

The PSA (pressure fluctuation adsorption) method uses an adsorbent, and by adsorbing oxygen in compressed air to the adsorbent, nitrogen having a concentration of about 99 to 99.99% is left over. It is possible to extract the gas.

In summary, the membrane separation method and PSA method can be expected to have a nitrogen gas concentration of 95% or more, which is the minimum concentration for industrial use, so they vary from semiconductor manufacturing processes to petrochemicals and food / beverage manufacturing. It can be used for various purposes.

As described above, since the ratio of oxygen to nitrogen in the air is about 2: 8, in order to generate nitrogen gas from the air, about 20% regardless of the membrane separation method or the PSA method. It is necessary to separate and remove oxygen. In this regard, if the oxygen concentration is reduced, such as by making the ratio of oxygen to nitrogen 1: 9, the amount of oxygen to be separated and removed can be reduced, so that the nitrogen gas generation efficiency is improved and the nitrogen gas is generated. The purity of nitrogen gas will also be improved, which will contribute to reducing the burden on the machine.

Exhaust gas discharged from the fuel cell can be considered as a reduced oxygen concentration. That is, a fuel cell generates electricity by chemically reacting hydrogen with oxygen in the air, and at that time, water and air having a reduced oxygen concentration are discharged. The air with reduced oxygen concentration is generally called nitrogen-rich gas.

Further, the fuel cell for industrial use can be installed mainly as a backup power supply device in a place where a power failure should be avoided, such as a factory, a hospital, a public office, and a computer server room.

Regarding the method of using the nitrogen-rich gas discharged from the fuel cell, JP-A-7-183041 (Patent Document 1), JP-A-7-183042 (Patent Document 2), and JP-A-2000-277138 (Patent Document 1). Technical proposals such as 3) have been made.

That is, the technical proposals according to the above Patent Documents 1 to 3 are technical proposals for using the nitrogen-rich gas discharged from the fuel cell as a gas for purging or sealing the same fuel cell, and are used for other purposes. It was not a technical proposal regarding the generation of nitrogen gas. The main reason for this is that the fuel cell does not emit nitrogen-rich gas having a nitrogen concentration of 95% or more, which is the minimum required for industrial use, in terms of the power generation efficiency of the fuel cell.

The applicant pays attention to the nitrogen-rich gas discharged from the fuel cell, and based on the idea that there is a method for improving the nitrogen concentration of the nitrogen-rich gas, the present applicant aims to generate a high-concentration nitrogen gas from the nitrogen-rich gas. A system and a method have been developed, leading to the proposal of "a high-concentration nitrogen gas generation system and a high-concentration nitrogen gas generation method" in the present invention.

Japanese Unexamined Patent Publication No. 7-183041 Japanese Unexamined Patent Publication No. 7-183042 Japanese Unexamined Patent Publication No. 2000-277138

In view of the above technical background, it is an object of the present invention to provide a system and a method for generating high-concentration nitrogen gas from exhaust gas discharged from a fuel cell.

In order to solve the above problems, the present invention is a system for generating high-concentration nitrogen gas from the exhaust gas of a fuel cell, and receives power from one or more hydrogen gas tanks and hydrogen supplied from the hydrogen gas tanks. The fuel cell is composed of a circulation path connecting the air supply port and the exhaust port provided in the fuel cell, and a circulation booster arranged at a predetermined intermediate point of the circulation path, and circulates from the exhaust port of the fuel cell. The air exhausted to the road is circulated by a circulation booster and sent to the fuel cell again from the air supply port, and by repeating this, the oxygen concentration of the circulating air is reduced and the nitrogen concentration is increased, resulting in a high concentration. Take measures to generate nitrogen gas.

Further, the present invention employs a means in which one or more pressure reducing valves are arranged after the circulation booster in the circulation path.

Further, the present invention employs a means in which a storage tank is arranged at an intermediate predetermined position in the circulation path.

Furthermore, the present invention is a method for generating high-concentration nitrogen gas from the exhaust of a fuel cell, in which the air exhausted from the exhaust port of the fuel cell is circulated by a circulation booster and again from the air supply port. By sending air to the fuel cell and repeating this process, the oxygen concentration in the circulating air is reduced and the nitrogen concentration is increased to generate a high-concentration nitrogen gas.

Furthermore, the present invention employs means in which the air supplied to the fuel cell is supplied in a state of being depressurized by the pressure reducing valve.

Further, the present invention also employs a means in which the air sent to the fuel cell and the air exhausted from the fuel cell are temporarily stored in a pressurized state in the storage tank.

According to the high-concentration nitrogen gas generation system and the high-concentration nitrogen gas generation method according to the present invention, the air exhausted from the exhaust port of the fuel cell to the circulation path is circulated by the circulation booster, and the air supply port is returned to the fuel cell. By repeatedly supplying air, it is possible to gradually reduce the oxygen concentration in the air supplied by the power generation in the fuel cell, and finally generate high-concentration nitrogen gas, which is discharged from the fuel cell. It has excellent effects such as contributing to the effective use of exhaust.

Further, according to the high-concentration nitrogen gas generation system and the high-concentration nitrogen gas generation method according to the present invention, the electric power generated by the fuel cell is used in a compressor or other equipment requiring AC power via an inverter, or When the commercial power supply is stopped, by using it as an emergency power supply outside the system, it is possible to keep the expensive fuel cell in a useful operating state without letting it idle, which improves cost efficiency. It has an excellent effect of contributing.

It is a system configuration schematic diagram which shows the 1st Embodiment of the high-concentration nitrogen gas generation system which concerns on this invention. It is a system configuration schematic diagram which shows the 2nd Embodiment of the high-concentration nitrogen gas generation system which concerns on this invention.

In the high-concentration nitrogen gas generation system and the high-concentration nitrogen gas generation method according to the present invention, the air exhausted from the exhaust port of the fuel cell to the circulation path is circulated by a circulation booster, and the air is sent from the air supply port to the fuel cell again. By repeating this process, the oxygen concentration of the circulating air is reduced and the nitrogen concentration is increased to generate a high-concentration nitrogen gas.
Hereinafter, embodiments of the high-concentration nitrogen gas generation system and the high-concentration nitrogen gas generation method according to the present invention, that is, the system configuration and operation will be described with reference to the drawings.

The high-concentration nitrogen gas generation system and the high-concentration nitrogen gas generation method according to the present invention are not particularly limited to the embodiments described below, and are within the scope of the technical idea of the present invention, that is, the same effects. It is possible to appropriately change the device capable of exhibiting the above, the material or shape of the device, and the like.

FIG. 1 is a schematic system configuration diagram showing a first embodiment of the high-concentration nitrogen gas generation system according to the present invention.
The high-concentration nitrogen gas generation system according to the present invention includes one or more hydrogen gas tanks 10, a fuel cell 20 that is supplied with hydrogen from the hydrogen gas tank 10 to generate electric power, and an air supply port 21 provided in the fuel cell 20. It is composed of a circulation path R connecting the exhaust port 22 and a circulation booster 30 arranged at a predetermined intermediate position of the circulation path R.

The hydrogen gas tank 10 is provided for the purpose of temporarily storing hydrogen gas and supplying the hydrogen gas to the fuel cell 20 via the hydrogen supply pipeline 12, and the stored hydrogen gas is used as the fuel cell. Connected to 20 so that it can flow out.

The fuel cell 20 supplies hydrogen gas to the hydrogen electrode 20a on the anode side and air to the air electrode 20b on the cathode side, respectively, and reacts them electrochemically to generate electricity and output DC power. The present invention is not particularly limited as long as it discharges water and nitrogen-rich gas having a reduced oxygen concentration at that time. That is, the elements provided in the reaction are hydrogen and oxygen, and the nitrogen concentration of the air discharged from the fuel cell 20 is relatively high due to the decrease in oxygen from the air due to the reaction, which is a nitrogen-rich gas. It is called.

The fuel cell 20 is provided with an air supply port 21 for supplying air to the cathode side 20b and an exhaust port 22 for discharging nitrogen-rich gas whose oxygen concentration has been reduced by the reaction, and also has a reaction. A drain discharge port 24 for draining the water generated by the above is provided. Then, one end of the circulation path R is connected to the air supply port 21, and the other end of the circulation path R is connected to the exhaust port 22, whereby the air supply port 21 and the exhaust port 22 are connected to the circulation path. It is connected via R. Further, in the circulation path R, one or a plurality of check valves 42 are provided as necessary in order to prevent backflow and ensure the flow of air in a certain direction.

A circulation booster 30 is arranged in a predetermined intermediate portion of the circulation path R. The circulation booster 30 is for pressurizing the air (nitrogen-rich gas) discharged from the fuel cell 20 and sending it out to the fuel cell 20 again, and the nitrogen-rich gas discharged from the fuel cell 20 is the circulation path R. The nitrogen-rich gas is connected so as to be able to flow out to the fuel cell 20 via the circulation path R. The pressurization amount of the nitrogen-rich gas in the circulation booster 30 may be the minimum pressurization amount required for circulation, and is not particularly limited, but is generally about 0.3 to 1 Mpa.

The circulation booster 30 is provided with an attached tank 31, and the attached tank 31 is pre-filled with compressed air. The filled compressed air is boosted and sent out to the fuel cell 20, and the nitrogen-rich gas discharged from the fuel cell 20 is returned to the attached tank 31. The air pressure of the compressed air initially filled in the attached tank 31 is not particularly limited, but is approximately 0.1 to 0.5 Mpa.

By the way, in the circulation path R, a mode in which a pressure reducing valve 40 is arranged in order to reduce the air pressure sent to the fuel cell 20 is adopted . This is arranged for the purpose of avoiding a high-pressure load on the cathode side 20b of the fuel cell 20, which is a cause of failure, in consideration of reaction efficiency. In order to achieve such a purpose, the pressure reducing valve 40 is circulated. It is arranged in the rear stage of the circulation booster 30 and in the front stage of the fuel cell 20 on the road R. The pressure reducing valve 40 is not limited to one, and a plurality of such pressure reducing valves 40 may be arranged in order to gradually reduce the air pressure in the circulation path R. The air pressure finally sent to the fuel cell 20 is not particularly limited, but it is desirable to reduce the pressure to about 0.05 Mpa.

Since the fuel cell 20 generates water by an electrochemical reaction, the nitrogen-rich gas discharged from the fuel cell 20 contains a large amount of water (water vapor), and the nitrogen-rich gas is contained in the circulation path R. It is assumed that the water (water vapor) is cooled as it passes through the circulation booster 30 and becomes water droplets to cause dew condensation. Therefore, it is preferable to dispose the gas-liquid separation device 44 at a predetermined position on the circulation path R to remove water (water vapor) from the nitrogen-rich gas discharged from the fuel cell 20. In order to achieve such an object, the gas-liquid separation device 44 is arranged in the rear stage of the fuel cell 20 and in the front stage of the circulation booster 30 in the circulation path R. Moisture (water vapor) removed by the gas-liquid separator 44 is appropriately discharged by the drain trap 44a.

Further, in order to measure the generation state of the high-concentration nitrogen gas, it is preferable to appropriately dispose the oxygen concentration meter M. By measuring the oxygen concentration in the circulating air, it is possible to relatively measure the nitrogen concentration in the air, and the oxygen concentration meter M can measure the generation state of high-concentration nitrogen gas. It is desirable that the oxygen concentration meter M is arranged at a position where the oxygen concentration can be finally measured in the attached tank 31 in which the high concentration nitrogen gas is finally stored.

According to the high-concentration nitrogen gas generation system according to the present invention configured as described above, high-concentration nitrogen gas of about 95% or more can be easily generated. The generated high-concentration nitrogen gas is once stored in the attached tank 31 of the circulation booster 30, then taken out from the attached tank 31 and transferred to another tank, and is appropriately used according to the purpose and application. ..

Next, the method for producing high-concentration nitrogen gas according to the present invention will be described. The method is mainly realized by the high-concentration nitrogen gas generation system according to the present invention described above.

(Step 1)
First, as a preliminary preparation, the attached tank 31 of the circulation booster 30 is filled with compressed air. The air pressure of the compressed air to be filled is not particularly limited, but is generally about 0.1 to 0.5 Mpa.

(Step 2)
By operating the circulation booster 30, the air in the attached tank 31 is boosted and supplied to the circulation path R, and the air is supplied to the fuel cell 20 via the circulation path R. The air pressure due to the boosting is not particularly limited, but is generally about 0.3 to 1 Mpa.
If necessary, the air pressure in the circulation path R is reduced to about 0.05 Mpa by the pressure reducing valve in the stage before the air is supplied to the fuel cell 20.

(Step 3)
By operating the fuel cell 20 in this state, hydrogen gas is supplied to the hydrogen electrode 20a on the anode side via the hydrogen supply pipeline 12, and the air supply port 21 is provided to the air electrode on the cathode side 20b. The air supplied from the circulation path R is supplied through the circulation path R, and power generation is started by an electrochemical reaction. By this reaction, in addition to electric power, water and air (nitrogen-rich gas) in which oxygen is reduced and the nitrogen concentration is relatively increased are generated from the air.

(Step 4)
The nitrogen-rich gas generated by the reaction in the fuel cell 20 is exhausted from the exhaust port 22 to the circulation path R and returned to the circulation booster 30.

In the process of repeating steps 2 to 4, that is, in the process of repeating air circulation between the fuel cell 20 and the circulation booster 30 via the circulation path R, the oxygen concentration in the circulating air gradually increases. As the nitrogen concentration decreases, the nitrogen concentration rises relatively, and finally a high concentration of nitrogen gas is produced.

The generated high-concentration nitrogen gas is once stored in the attached tank 31 of the circulation booster 30, then taken out from the attached tank 31 and transferred to another tank, and is appropriately used according to the purpose and application. ..

The water generated in the fuel cell 20 in the process of step 3 is appropriately discharged through the drain discharge port 24.
Further, the electric power generated in the process of the above step 3 can be transmitted to the outside as a commercial power source by converting it into AC electric power via an inverter as necessary, or in the circulation booster 30 or this system. It can be used as a power source for other devices that require electric power.

According to the high-concentration nitrogen gas generation method according to the present invention configured as described above, a high-concentration nitrogen gas of about 95% or more can be easily generated, and the generated high-concentration nitrogen gas can be used for various purposes. Will be offered to.

Other examples will be described. The same part as in the first embodiment is omitted.
In the first embodiment, the attached tank 31 of the circulation booster 30 is filled with the initially compressed air, and the generated high-concentration nitrogen gas is temporarily stored in the attached tank 31 and then taken out from the attached tank 31. The modes to be used as appropriate have been described. However, depending on the capacity of the attached tank 31 provided in the circulation booster 30, the generation of high-concentration nitrogen gas is completed immediately, and it may be necessary to frequently stop the operation in order to take out the nitrogen gas from the attached tank 31. Can also be assumed.
Therefore, there has been a demand for a technique capable of storing a certain amount of nitrogen gas.

FIG. 2 is a schematic system configuration diagram showing a second embodiment of the high-concentration nitrogen gas generation system according to the present invention.
The high-concentration nitrogen gas generation system according to the present invention adopts a configuration in which a storage tank 50 is arranged at an intermediate predetermined position in the circulation path R.

The storage tank 50 is for storing the initial compressed air and temporarily storing the nitrogen-rich gas and the high-concentration nitrogen gas generated by the fuel cell 20, and the nitrogen-rich gas discharged from the fuel cell 20. Is connected so as to be able to flow in through the circulation path R, and the nitrogen-rich gas is connected so as to be able to flow out to the fuel cell 20 via the circulation path R. The storage tank 50 is also a place where the high-concentration nitrogen gas is finally stored, and it is desirable that the storage tank 50 is equipped with an oxygen concentration meter M in order to measure the generation state of the high-concentration nitrogen gas in the tank.

By the way, the relationship of the arrangement position of the storage tank 50 with the circulation booster 30 similarly arranged at the intermediate predetermined position of the circulation path R is not particularly limited in terms of the function and operation effect of the present invention. Considering the storage capacity and circulation action of the gas (air, nitrogen-rich gas, high-concentration nitrogen gas) stored in the storage tank 50, it is preferable to store the inside of the tank in a higher pressure state, as shown in the figure. It is desirable that the circulation booster 30 is arranged after the circulation booster 30 and before the fuel cell 20 in the circulation path R. At this time, the position of the pressure reducing valve 40 is the rear stage of the storage tank 50 and the front stage of the fuel cell 20.

According to the high-concentration nitrogen gas generation system according to the present invention configured as described above, it not only contributes to the generation of high-concentration nitrogen gas, but also cools the nitrogen-rich gas that flows in with heat and smoothes the pulse pressure. It is also effective in. The generated high-concentration nitrogen gas is temporarily stored in the storage tank 50 and the attached tank 31, and then taken out from the storage tank 50 and the attached tank 31 and transferred to another tank as appropriate according to the purpose and application. used.

Next, the method for producing high-concentration nitrogen gas according to the present invention will be described. The method is mainly realized by the high-concentration nitrogen gas generation system according to the present invention described above.

(Step 1)
First, as a preliminary preparation, the storage tank 50 is filled with compressed air. The air pressure of the compressed air to be filled is not particularly limited, but is generally about 0.1 to 0.5 Mpa.

(Step 2)
By operating the circulation booster 30, the air in the attached tank 31 is boosted and supplied to the circulation path R, and the air is supplied to the storage tank 50 via the circulation path R. The air pressure due to the boosting is not particularly limited, but is generally about 0.3 to 1 Mpa.

(Step 3)
The air sent to the storage tank 50 is integrated with the compressed air filled in advance, and is further sent to the fuel cell 20 in the subsequent stage via the circulation path R.
If necessary, the air pressure in the circulation path R is reduced to about 0.05 Mpa by the pressure reducing valve in the stage before the air is supplied to the fuel cell 20.

(Step 4)
By operating the fuel cell 20 in this state, hydrogen gas is supplied to the hydrogen electrode 20a on the anode side via the hydrogen supply pipeline 12, and the air supply port 21 is provided to the air electrode on the cathode side 20b. The air supplied from the circulation path R is supplied through the circulation path R, and power generation is started by an electrochemical reaction. By this reaction, in addition to electric power, water and air (nitrogen-rich gas) in which oxygen is reduced and the nitrogen concentration is relatively increased are generated from the air.

(Step 5)
The nitrogen-rich gas generated by the reaction in the fuel cell 20 is exhausted from the exhaust port 22 to the circulation path R and returned to the circulation booster 30.

In the circulating air, the steps 2 to 5 are repeated, that is, in the process of repeating the air circulation between the fuel cell 20, the circulation booster 30, and the storage tank 50 via the circulation path R. As the oxygen concentration of the fuel cell gradually decreases, the nitrogen concentration increases relatively, and finally a high concentration of nitrogen gas is produced.

The generated high-concentration nitrogen gas is temporarily stored in the storage tank 50 and the attached tank 31, and then taken out from the storage tank 50 and the attached tank 31 and transferred to another tank as appropriate according to the purpose and application. used.

The water generated in the fuel cell 20 in the process of step 4 is appropriately discharged through the drain discharge port 24.
Further, the electric power generated in the process of step 4 is converted to AC electric power via an inverter as necessary and transmitted to the outside as a commercial power source, or in the circulation booster 30 or this system. It can be used as a power source for other devices that require electric power.

According to the high-concentration nitrogen gas generation method according to the present invention configured as described above, high-concentration nitrogen gas can be easily generated, and the nitrogen-rich gas flowing in with heat can be cooled and the pulse pressure can be reduced. It works effectively even in smoothing, and the generated high-concentration nitrogen gas will be used for various purposes.

The present invention is an invention relating to the production of nitrogen gas, and the fields of utilization of the nitrogen gas can be used in a wide range of fields such as semiconductor manufacturing processes, petrochemistry, foods and beverages. In the field of generation and utilization of such nitrogen gas, its purity and efficiency of production are required, and the present invention can realize all of these requirements as described in the above-mentioned "Effects of the Invention". Is what you do. Therefore, it is considered that the industrial applicability of the "high-concentration nitrogen gas generation system and the high-concentration nitrogen gas generation method" in the present invention is great.

10 Hydrogen gas tank 12 Hydrogen supply pipeline 20 Fuel cell 20a Hydrogen pole 20b Air pole 21 Air supply port 22 Exhaust port 24 Drain discharge port 30 Circulation booster 31 Attached tank 40 Pressure reducing valve 42 Check valve 44 Gas-liquid separator 44a Drain trap 50 Storage tank M Oxygen meter R Circulation path

Claims (4)

A system for producing high-concentration nitrogen gas from fuel cell exhaust.
With one or more hydrogen gas tanks,
A fuel cell that receives the supply of hydrogen from the hydrogen gas tank and generates electric power,
A circulation path connecting the air supply port and the exhaust port provided in the fuel cell,
A circulation booster arranged at a predetermined intermediate point of the circulation path, and
It consists of one or more pressure reducing valves arranged in the rear stage of the circulation booster and in the front stage of the fuel cell in the circulation path.
The air exhausted from the exhaust port of the fuel cell to the circulation path is circulated by the circulation booster and sent to the fuel cell again from the air supply port, and by repeating this, the oxygen concentration of the circulating air is reduced and the nitrogen concentration. A high-concentration nitrogen gas generation system characterized by producing a high-concentration nitrogen gas by increasing the amount of nitrogen gas. The high-concentration nitrogen gas generation system according to claim 1, wherein a storage tank is arranged at an intermediate predetermined position in the circulation path. A method for producing high-concentration nitrogen gas from fuel cell exhaust.
The air exhausted from the exhaust port of the fuel cell is circulated by the circulation booster, depressurized by the pressure reducing valve, and then sent to the fuel cell again from the air supply port, and by repeating this, the oxygen concentration of the circulating air is increased. A method for producing a high-concentration nitrogen gas, which comprises reducing and increasing the nitrogen concentration to generate a high-concentration nitrogen gas. The high-concentration nitrogen gas generation according to claim 3, wherein the air sent to the fuel cell and the air exhausted from the fuel cell are temporarily stored in a pressurized state in the storage tank. Method.

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