JP2004247290A - Hydrogen feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently generate hydrogen from a raw material gas, in a hydrogen feeder to generate electric power and hydrogen by using a fuel cell. <P>SOLUTION: This hydrogen feeder 1 is provided with a reformer 2 to reform a natural gas, a fuel cell 3 to generate electric power by the reformed gas from the reformer 2, and a refiner 4 to refine hydrogen from the exhaust gas of the fuel cell 3. The refiner 4 is provided with a PEM 9 to carry out refining by a membrane separation method and a PSA 11 to carry out refining by a pressure swing adsorption method. The reformed gas from the reformer 2 is used for power generation of the fuel cell 3 without refining it, and hydrogen is refined from the exhaust gas of the fuel cell 3 in the refiner 4. In addition, the off-gas of the PEM 9 is used in a heater 8, and the off-gas of the PSA 11 is used in the fuel cell 3. Thereby, since an amount of hydrogen burnt in the heater 8 reduces in comparison with the past, electric power and hydrogen can be generated by further efficiently using hydrogen contained in the raw material gas. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a hydrogen supply device that reforms a raw material gas such as natural gas, purifies hydrogen, and generates power using a fuel cell in each home or fuel station.

  2. Description of the Related Art In recent years, it has been considered to generate power using a fuel cell in a general home and supply power to electric equipment used in the home. In recent years, efforts have been made to spread the use of automobiles (hereinafter, referred to as “fuel cell vehicles”) that generate electric power using a fuel cell and drive by driving a motor with the generated electric power. When using these fuel cells, how to supply hydrogen gas as a fuel is a problem, and there is an urgent need to establish a hydrogen station such as a current gas station.

  As a conventional hydrogen supply device 31, one disclosed in Patent Document 1 below is known. The hydrogen supply device 31 will be described in a simplified manner. As shown in FIG. 4, a reformer 32 for reforming a raw material gas such as a city gas, and hydrogen from the reformed gas reformed by the reformer 32 are provided. It is provided with a purifying device 33 for purifying, a fuel cell 34 for generating electric power with the purified hydrogen, and a storage tank 35 for storing the hydrogen purified by the purifying device 33 and the hydrogen not used in the fuel cell 34. . 4 is a blower that extracts exhaust gas from the fuel cell 34. The electric power generated by the fuel cell 34 is stored in the battery 37 and is used in devices such as the refining device 33.

Here, the reformer 32 is provided with a heater 38 for heating and reforming the raw material gas. On the other hand, since the off-gas from the refining device 33 contains hydrogen in addition to carbon monoxide, it can be used as fuel. Therefore, in the conventional hydrogen supply device 31, the raw material gas is reformed by burning the off-gas from the purification device 33 with the heater 38 as an auxiliary fuel. In addition, when a sufficient amount of heat cannot be obtained in the heater 38 by only the off-gas from the refining device 33, the raw material gas is supplied to the heater 38 as it is (not shown).
JP-A-5-182683 (page 3, FIG. 1)

  As described above, in the conventional hydrogen supply device 31, the off-gas from the refining device 33 is used as the auxiliary fuel for the heater 38, so that the waste of the source gas can be suppressed. Not a little remains. For this reason, there has been a demand for an apparatus capable of efficiently generating hydrogen from a raw material gas.

  An object of the present invention is to improve a hydrogen supply device, and more specifically, to provide a hydrogen supply device capable of efficiently generating hydrogen from a raw material gas in order to solve the above-mentioned disadvantages.

  In order to achieve the above object, a hydrogen supply device of the present invention includes a reforming unit that reforms a raw material gas containing a hydrocarbon to generate a hydrogen-rich reformed gas, and a fuel that generates power using the reformed gas. A fuel cell; and a purifying unit for purifying hydrogen from exhaust gas discharged from the fuel cell.

  According to the hydrogen supply device of the present invention, power is generated in the fuel cell by the reformed gas reformed by the reforming means, and then hydrogen is purified from the exhaust gas of the fuel cell by the purifying means. That is, instead of purifying hydrogen from the reformed gas from the reforming means by the purifying means as in the related art, and performing power generation in the fuel cell using the purified hydrogen, power generation is performed in the fuel cell using the reformed gas. Hydrogen is purified from the exhaust gas of fuel cells. Thus, by purifying the exhaust gas of the fuel cell by the purifying means, the amount of off-gas discharged from the purifying means can be reduced. According to experiments performed by the inventors of the present application, since the hydrogen supply device of the present invention can efficiently generate hydrogen from a source gas, even when the same power is generated using the same amount of the source gas, However, the amount of hydrogen that can be stored has been greatly increased as compared with the conventional apparatus.

Further, in the hydrogen supply device of the present invention, it is preferable that the purifying unit purifies the hydrogen by a membrane separation method using a hydrogen permeable membrane and a pressure swing adsorption method. In the membrane separation method, CO ^{2 and the} like can be efficiently separated from a raw material gas, but water cannot be removed. Therefore, water is removed by a pressure swing adsorption method that can efficiently remove water. Here, the membrane separation method using a hydrogen permeable membrane is called PEM (Proton Exchange Membrane) purification, and the pressure swing adsorption method is generally called PSA (Pressure Swing Adsorption), which is known as a method for purifying hydrogen. Is the way.

  More specifically, the refining means includes a membrane separator for performing membrane separation using a hydrogen permeable membrane, a refining pressurizer for pressurizing a gas purified by the membrane separator, and pressurization by the refining pressurizer. And an adsorber for purifying the gas by a pressure swing adsorption method. Further, the purifying means may make the membrane separator have a hydrogen pressurizing function, so that a subsequent purifying press may not be required. Further, the adsorber for performing the pressure swing adsorption method includes a plurality of containers filled with an adsorbent, and purifies hydrogen by passing the plurality of containers while changing the pressure of the gas to be purified.

  The membrane separator performing the membrane separation method in the purifying means may perform hydrogen separation by providing electrodes on both sides of the hydrogen permeable membrane and applying a potential difference to the front and back of the hydrogen permeable membrane to allow hydrogen ions to pass therethrough. preferable. The hydrogen permeable membrane can transmit hydrogen by applying pressure even when there is no potential difference between the front and back surfaces.However, it is possible to transmit hydrogen ions more quickly by applying a potential difference and transmitting hydrogen ions. Can be.

  Further, in the hydrogen supply device of the present invention, when the reforming means reforms the raw material gas by heating with a heating means using the raw material gas as a fuel, the reforming means performs the reforming when performing the reforming. The off-gas separated by the membrane separation method is used as the fuel in addition to the source gas, and the fuel cell generates power using the off-gas separated by the pressure swing adsorption method in addition to the reformed gas. Is preferred. Since the offgas separated by the membrane separation method contains components that can be used as fuel, such as carbon monoxide and hydrogen, the offgas is burned by the heating means to use the raw material gas without waste. be able to. Further, since only hydrogen and moisture are contained in the off-gas separated by the pressure swing adsorption method, the purity of hydrogen is high. Therefore, the off-gas is supplied to the fuel cell to more effectively generate hydrogen in the source gas. Can be used.

  More specifically, the reforming means reforms the raw material gas by heating with a heater using the raw material gas as a fuel, and in addition to the raw material gas as a fuel of the heater when performing the reforming. It is preferable that the off-gas separated by the membrane separator is used, and the fuel cell generates power using the off-gas separated by the adsorber in addition to the reformed gas.

  Further, in the hydrogen supply device of the present invention, the hydrogen purified by the purifying means may be directly supplied to an automobile using the hydrogen, but the hydrogen supplying apparatus may include a storage means for storing the hydrogen purified by the purifying means. Good. Preferably, the storage means includes a storage pressurizing means for pressurizing the stored hydrogen gas, and a connection means connected to a vehicle using hydrogen. When supplying hydrogen to the vehicle, it is desirable to move hydrogen from the storage unit to the vehicle promptly.However, since the storage unit is provided with a pressurizing unit for storage, the hydrogen is quickly pressurized by pressurizing the hydrogen. Hydrogen can be supplied to the vehicle.

  More specifically, a storage unit for storing hydrogen purified by the purification unit is provided, and the storage unit is provided with a first tank that stores gas supplied from the adsorber, and a storage unit that is supplied from the first tank. A pressurizing device for pressurizing gas, a second tank for storing gas supplied from the pressurizing device, and a connector for connecting the second tank to a vehicle using hydrogen as fuel. Will be provided.

  Next, an example of an embodiment of the hydrogen supply device of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a hydrogen supply device of the present embodiment, FIG. 2 is an explanatory diagram showing a main part of PEM purification, and FIG. 3 is a block diagram showing a purification device of another embodiment of the present invention.

  The hydrogen supply device 1 of the present embodiment generates electric power by using city gas in each household, supplies electric power to electric appliances in the household, and generates hydrogen for replenishing a fuel cell vehicle 19 described later. It is. As shown in FIG. 1, the hydrogen supply device 1 includes a reformer 2 that reforms natural gas as a raw material gas, and a fuel cell 3 that generates power using the reformed gas sent from the reformer 2. , A purifier 4 for purifying hydrogen sent from the fuel cell 3, a low-pressure tank 5 (first tank), a high-pressure compressor 6 (storage pressurizer), and a high-pressure tank 7 (first tank) connected to the purifier 4. 2 tanks).

  The reformer 2 includes a heater 8. The purification device 4 includes a PEM 9 (membrane separator) for performing membrane separation by the hydrogen permeable membrane 16, a low-pressure compressor 10 (purification pressurizer) for compressing hydrogen gas from the PEM 9 at low pressure (about 0.7 MPa), and a low-pressure compressor. A PSA 11 (adsorber) for purifying hydrogen gas from the compressor 10 by a pressure swing adsorption method is provided.

  Further, the hydrogen supply device 1 transmits a connector 12 connected to a gas pipe (not shown) to which natural gas is supplied, a connector 13 connected to a fuel cell vehicle 19, and electric power generated by the fuel cell 3 to the outside. And a connector 14 to be connected. In FIG. 1, the path of the electric power generated by the fuel cell 3 is indicated by a dotted line. The electric power generated by the fuel cell 3 is stored by the battery 15, supplied to the PEM 9, the low-pressure compressor 10, the PSA 11, and the high-pressure compressor 6, and further output from the connector 14 for external electric equipment.

  As shown in FIG. 2, the PEM 9 according to the present embodiment includes a hydrogen permeable film 16 and an anode plate 17 and a cathode plate 18 attached to both surfaces thereof. A voltage from the battery 15 is applied to both electrodes. The hydrogen permeable film 16 has a property of passing hydrogen ions (protons). In the present embodiment, a material obtained by applying a catalyst to a fluorine-based ion exchange resin such as Nafion of DuPont is used. Both the anode plate 17 and the cathode plate 18 are a porous sheet-like electrically conductive material. In this embodiment, porous carbon paper is used.

  The PSA 11 in the present embodiment includes a plurality of adsorption chambers filled with an adsorbent such as activated carbon (not shown). Hydrogen gas is supplied to the plurality of adsorption chambers from the low-pressure compressor 10 and adsorption, decompression, washing, and pressure increase are performed to purify hydrogen.

  As shown in FIG. 1, the fuel cell vehicle 19 includes a hydrogen tank 20 and a fuel cell 21. The fuel cell 21 uses the hydrogen stored in the hydrogen tank 20 as fuel to generate power, and drives a motor (not shown). Is to run. In the present embodiment, since the reformer 2, the fuel cell 3, and the like have the same configuration as those conventionally used, detailed description will be omitted.

Next, the operation of the hydrogen supply device 1 of the present embodiment will be described with reference to FIG. First, when natural gas as a raw material gas is supplied from a gas pipe (not shown) connected to the connector 12, the reformer 2 reforms the natural gas. Here, the natural gas is supplied in an amount of 4.2 m ³ per hour as shown in FIG. In the present embodiment, “m ³ ” indicating the volume of the gas indicates the volume per hour.

The reformer 2 reacts natural gas with water and air (oxygen in the air) from a water supply source (not shown) to generate a hydrogen-rich reformed gas containing a large amount of hydrogen. The reformed gas generated by the reformer 2 is about 10.0 m ³ , and the hydrogen concentration in the reformed gas is about 40%. The reformed gas contains carbon monoxide, carbon dioxide, nitrogen, unreacted natural gas, and moisture, in addition to hydrogen. Then, about 1.8 m ³ (about 100% of hydrogen) from the PSA 11 described later is added to the reformed gas, and about 11.8 m ³ (about 44% of hydrogen) is supplied to the fuel cell 3.

The fuel cell 3 generates electric power using the supplied hydrogen-containing gas as fuel. At this time, about 4.2 m ³ of hydrogen is consumed by the fuel cell 3. The exhaust gas discharged from the fuel cell 3 is about 7.6 m ³ , and the hydrogen content is about 34%.

Next, hydrogen is purified from the exhaust gas from the fuel cell 3 by the purifier 4. Specifically, about 5.8 m ³ of a gas of about 100% hydrogen is purified by PEM9. At this time, the purified gas also contains moisture. Here, the purification of hydrogen by the PEM 9 will be described with reference to FIG. In the PEM 9, a voltage is applied between the anode plate 17 and the cathode plate 18 to generate a potential difference between the front and back of the hydrogen permeable film 16.

  When the reforming gas is supplied from the reformer 2 in this state, the hydrogen gas releases electrons on the anode plate 17 to become hydrogen ions, and the released electrons are moved to the cathode plate 18 via the battery 15. . On the other hand, hydrogen ions permeate the hydrogen permeable membrane 16 and touch the cathode plate 18, receive electrons from the anode plate 17 and become hydrogen gas. As described above, in the PEM 9, hydrogen is purified from the reformed gas, but moisture is also guided to the downstream side through the electrodes 17 and 18 and the hydrogen permeable membrane 16. On the other hand, since the off-gas from the PEM 9 contains not only hydrogen but also natural gas which has not reacted with carbon monoxide, this off-gas is burned in the heater 8 and used for heating the reformer 2.

  Next, the hydrogen gas containing water is compressed by the low-pressure compressor 10 as necessary and sent to the PSA 11, and the PSA 11 removes the water to further improve the purity.

The hydrogen purified by the PSA 11 becomes about 4.0 m ^{3 as} shown in FIG. 1, and is temporarily stored in the low-pressure tank 5. Further, the hydrogen gas exceeding the storage amount of the low-pressure tank 5 is sent to the high-pressure compressor 6 and compressed (about 30 MPa), and stored in the high-pressure tank 7. When hydrogen is supplied to the fuel cell vehicle 19, high-pressure hydrogen is supplied from the high-pressure tank 7 to the hydrogen tank 20 of the fuel cell vehicle 19 via the connector 13.

  Here, in order to compress the hydrogen gas by the high-pressure compressor 6, it is necessary to sufficiently remove water by the PSA 11. If high-humidity hydrogen gas is compressed at high pressure, a large amount of drain water is generated, and various adverse effects such as water lock of a cylinder (not shown) in the high-pressure compressor 6 and corrosion of the high-pressure tank 7 occur. The dew point of the hydrogen gas after purification by the PSA 11 depends on the compression conditions of the high-pressure compressor 6, but is preferably -30 ° C or less at atmospheric pressure.

On the other hand, in the PSA 11, only hydrogen is purified from the hydrogen gas containing water, but the off-gas from the PSA 11 contains about 1.8 m ³ of hydrogen in addition to the water. In the present embodiment, hydrogen contained in the off-gas from the PSA 11 is used as fuel for the fuel cell 3.

As described above, the hydrogen supply device 1 of the present embodiment can finally generate 4.0 m ³ of hydrogen from 4.2 m ³ of natural gas.

Here, as a comparative example, a case where the same electric power as that of the present embodiment is generated in the fuel cell 34 using 4.2 m ³ of hydrogen in the conventional example shown in FIG. In the conventional example shown in FIG. 4, 3.8 m ³ of hydrogen gas is stored in the storage tank 35 because the purification of hydrogen is performed only by the purification device 33. However, since the hydrogen gas that has passed through the fuel cell 34 always contains moisture, dry hydrogen gas suitable for compression by a high-pressure compressor cannot be obtained with only the purification device 33. Therefore, if the condition that the moisture in the hydrogen gas is removed by the purification using PSA is added as in the present embodiment, the generated hydrogen becomes about 2.6 m ³ .

The fuel cell 3 of the present embodiment and the fuel cell 34 of the comparative example generate the same electric power, but the amount of hydrogen consumed in the fuel cell 3 of the present embodiment is 4.2 m. ³ , and the consumption of hydrogen in the fuel cell 34 of the comparative example is 3.8 m ³ . This is because, in the present embodiment, power is not generated by the fuel cell using 100% purified hydrogen, but is generated by using the hydrogen-rich gas reformed by the reformer 2. Therefore, it is considered that the power generation efficiency of the fuel cell 3 alone has decreased.

However, in this embodiment, hydrogen is purified from the exhaust gas after power generation in the fuel cell 3 by the PEM 9 and the off gas is supplied to the heater 8, and the off gas of the PSA 11 is supplied to the fuel cell 3. Power generation. As described above, of the raw material gas, the off-gas burned by the heater 8 is 2.4 m ^{3 in the} comparative example, but is 1.8 m ³ in the present embodiment. In the present embodiment, the utilization rate of hydrogen in the entire system is improved by efficiently using the hydrogen in the raw material gas.

Therefore, in the comparison between the two, under the condition that the power generation amounts of the fuel cells 3 and 34 are the same using the same amount of the source gas, the hydrogen that can be stored in the conventional example is about 2.6 m ³ , Thus, in the present embodiment, it was able to be greatly improved to 4.0 m ³ .

  Next, another embodiment of the present invention will be described with reference to FIG. In this embodiment, when compressing the hydrogen gas in the purifier 4 ', the compression is performed by the PEM 9' having a hydrogen compression function without using the low-pressure compressor 10. In the refining device 4 ', the voltage of the battery 15 supplied to the PEM 9' is higher than the voltage supplied to the PEM 9 of the above embodiment. In the PEM 9 ′, pressure can be applied to the hydrogen gas that has passed through the hydrogen permeable film 16 in accordance with the increase in the electric energy. As described above, if the pressure is applied to the hydrogen gas by the PEM 9 ′, the pressure of the hydrogen gas can be increased efficiently because there is no mechanical loss as in a normal compressor.

  In the present embodiment, a case has been described in which each household uses city gas as a source gas to generate power using the fuel cell 3 and supplies hydrogen to the fuel cell vehicle 19. However, the present invention is not limited to this. As described above, the present invention may be applied to a hydrogen station that supplies hydrogen to a fuel cell vehicle 19 or a hydrogen vehicle equipped with an internal combustion engine using hydrogen as fuel.

  In the present embodiment, the hydrogen is temporarily stored in the low-pressure tank 5 and the high-pressure tank 7. However, the present invention is not limited to this, and the hydrogen gas from the PSA 11 is compressed by the high-pressure compressor 6 and the hydrogen tank of the fuel cell vehicle 19 is compressed. 20 may be supplied directly.

  Further, in the present embodiment, since the apparatus for supplying hydrogen to the fuel cell vehicle 19 has been described, the purity of the hydrogen gas is increased by the PSA 11 and the hydrogen is stored in the high-pressure tank 7. However, when supplying hydrogen for power generation in a fixed facility, hydrogen purified by the PEM 9 may be stored in the low-pressure tank 5. In this case, the PSA 11, the high-pressure compressor 6, and the high-pressure tank 7 become unnecessary.

  Further, in the present embodiment, the fluorine-based ion exchange resin is used as the hydrogen permeable membrane 16 in the PEM 9, but the present invention is not limited to this, and any other known membrane that can transmit hydrogen gas or hydrogen ions is used. May be used. In addition, although porous carbon paper is used for the anode plate 17 and the cathode plate 18, the invention is not limited thereto, and a known technique such as depositing a metal on the hydrogen permeable film 16 to form each electrode may be used. Good.

FIG. 2 is a block diagram showing a configuration of the hydrogen supply device according to the embodiment. Explanatory drawing which shows the principal part of PEM purification. FIG. 6 is a block diagram showing a purification device according to another embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a conventional hydrogen supply device.

Explanation of reference numerals

  DESCRIPTION OF SYMBOLS 1 ... Hydrogen supply apparatus, 2 ... Reformer, 3 ... Fuel cell, 4 ... Purification apparatus.

Claims (11)

  Reforming means for reforming a raw material gas containing hydrocarbons to generate a hydrogen-rich reformed gas, a fuel cell for generating power using the reformed gas, and purifying hydrogen from exhaust gas discharged from the fuel cell A hydrogen supply device comprising: a purification unit.   2. The hydrogen supply device according to claim 1, wherein the purification unit purifies the hydrogen by a membrane separation method using a hydrogen permeable membrane and a pressure swing adsorption method. 3.   The purification means includes a membrane separator for performing membrane separation using a hydrogen permeable membrane, a purification pressurizer for pressurizing the gas purified by the membrane separator, and a pressure swing of the gas pressurized by the purification pressurizer. The hydrogen supply device according to claim 1, further comprising an adsorber for purifying by an adsorption method.   The purifying means includes a membrane separator for performing membrane separation using a hydrogen permeable membrane having a hydrogen pressurizing function, and an adsorber for purifying a gas pressurized by the membrane separator by a pressure swing adsorption method. The hydrogen supply device according to claim 1, wherein:   The membrane separator performing the membrane separation method in the purifying means, by providing electrodes on both surfaces of the hydrogen permeable membrane, applying a potential difference to the front and back of the hydrogen permeable membrane to allow hydrogen ions to permeate to separate hydrogen. The hydrogen supply device according to any one of claims 2, 3, and 4, wherein:   The adsorber performing the pressure swing adsorption method includes a plurality of containers filled with an adsorbent, and purifies hydrogen by passing the plurality of containers while varying the pressure of the gas to be purified. The hydrogen supply device according to any one of claims 2, 3, and 4.   The reforming means reforms the raw material gas by heating by a heating means using the raw material gas as a fuel, and separates by the membrane separation method in addition to the raw material gas as a fuel of the heating means when performing the reforming. 3. The hydrogen supply device according to claim 2, wherein the generated off-gas is used, and the fuel cell generates power using the off-gas separated by the pressure swing adsorption method in addition to the reformed gas. 4.   The reforming means reforms the raw material gas by heating with a heater using the raw material gas as a fuel, and separates by the membrane separator in addition to the raw material gas as a fuel of the heater when performing the reforming. 5. The hydrogen supply device according to claim 3, wherein the off-gas is used, and the fuel cell performs power generation using the off-gas separated by the adsorber in addition to the reformed gas. 6.   The hydrogen supply device according to any one of claims 1 to 8, further comprising a storage unit configured to store the hydrogen purified by the purification unit.   The hydrogen storage device according to claim 9, wherein the storage device includes a storage pressurizing device that pressurizes stored hydrogen gas, and a connection device that is connected to a vehicle that uses hydrogen as a fuel. Feeding device. A storage unit for storing hydrogen purified by the purification unit,
The storage means includes a first tank that stores gas supplied from the adsorber, a storage pressurizer that pressurizes the gas supplied from the first tank, and a gas that is supplied from the storage pressurizer. 9. The vehicle according to claim 3, further comprising a second tank for storing, and a connector for connecting the second tank to a vehicle using hydrogen as fuel. Hydrogen supply equipment.

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