JP2006261030A - Fuel cell power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell power generation system which can prevent a hydrogen storage alloy from deterioration caused by impurity gasses included in a reformed gas and which can prevent a fuel cell from decreasing of power generation output of the fuel cell caused by CO. <P>SOLUTION: The fuel cell power generation system includes a reformed gas formation portion 1 forming a reformed gas, in which hydrogen is a principal component, by steam reforming of a hydrocarbon-type fuel, a gas separation membrane 2 raising a volume fraction of hydrogen and lowering that of CO by transmitting the reformed gas, a hydrogen storage alloy 3 being supplied with the reformed gas transmitted through the gas separation membrane 2, and a fuel cell 4 generating an electric power by using hydrogen stored in the hydrogen storage alloy 3. The gas separation membrane 2 contains no noble metal substantially and a surface reforming treatment to prevent poisoning by CO is applied to the hydrogen storage alloy 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell power generation system in which hydrogen of a reformed gas obtained by steam reforming a hydrocarbon-based fuel is stored in a hydrogen storage alloy, and power is generated in the fuel cell using hydrogen released from the hydrogen storage alloy. Is.

  Conventionally, there has been a fuel cell power generation system including a reformed gas generation unit that generates a reformed gas mainly composed of hydrogen by steam reforming a hydrocarbon-based fuel, and a fuel cell that generates electric power using the reformed gas. Are known.

FIG. 3 shows an example of a conventional fuel cell power generation system. The reformed gas generation unit includes a reforming unit that generates a reformed gas containing hydrogen as a main component through a steam reforming reaction, a CO conversion unit that reduces CO contained in the reformed gas, and a reformer that is output from the CO conversion unit. It is formed with a CO selective oxidation reaction part for further reducing CO contained in the gas. In this system, the reformed gas generated in the reformed gas generator contains impurity gases such as CO, CO ₂ , and CH ₄ , and the reformed gas containing the impurity gases is supplied to the fuel cell. Therefore, it is necessary to always supply a reformed gas containing a larger amount of hydrogen than that required for power generation to the fuel cell. For this reason, it has been necessary to treat off-gas such as hydrogen that has not been used for power generation in the fuel cell in the combustion section or the like. In addition, it is necessary to adjust the amount of reformed gas generated in the reformed gas generation unit according to the fluctuation of the power generation load and supply it to the fuel cell, which causes a problem that the control of the reformed gas generation unit becomes complicated. .

In order to solve these problems, a fuel cell power generation system using a hydrogen storage alloy as shown in FIG. 4 has been proposed (see Patent Document 1). In this system, the reformed gas generator is composed of a reformer and a CO shifter, and the reformed gas generated in the reformed gas generator is mainly composed of hydrogen and has a volume fraction of CO of 1% or less. Has been reduced. This reformed gas is supplied to the hydrogen storage alloy. Since the hydrogen storage alloy selectively stores only hydrogen, impurity gases such as CO, CO ₂ , and CH ₄ contained in the reformed gas are stored when hydrogen is stored. Can be recovered without being supplied to the fuel cell. Therefore, since hydrogen stored in the hydrogen storage alloy is released during power generation of the fuel cell, only hydrogen can be supplied to the fuel cell. This eliminates the need for off-gas processing, and allows the fuel cell to be supplied with hydrogen from the hydrogen storage alloy in an amount necessary for power generation, thus making it easy to cope with fluctuations in power generation load.

  Here, when CO is contained in the reformed gas generated in the reformed gas generation section, there is a problem that the hydrogen storage capacity of the hydrogen storage alloy is reduced, or the storage and release of the reformed gas containing CO. If the process is repeated, the hydrogen storage alloy deteriorates, and there is a problem that the ability to store and release hydrogen gradually decreases. For this reason, in the thing of patent document 1, it was necessary to provide in the reformed gas production | generation part the CO conversion part for fully reducing CO contained in reformed gas.

  In addition, reformed gas is generated by a membrane reformer (hydrogen separation type reformer), or the reformed gas generated by the reformed gas generator is formed of a Pd film or a polymer film as shown in FIG. A fuel cell power generation system has been proposed in which the hydrogen storage alloy stores the CO after reducing the CO contained in the reformed gas through the gas separation membrane (see Patent Document 2, etc.). In this system, when a membrane reformer is used, there is a problem that a power for securing a large pressure difference of about 0.5 to 1 MPa is required between the primary side and the secondary side of the hydrogen permeable membrane. Alternatively, when the reformed gas is passed through the gas separation membrane, there is a problem that the noble metal membrane such as a Pd membrane is very expensive in addition to the performance deterioration due to the pinhole expansion, and the polymer membrane contains hydrogen and impurity gas. Since the separation factor is not sufficient, in order to sufficiently reduce CO, there is a problem that it is necessary to arrange polymer membranes in multiple stages and the system becomes complicated.

In addition, when the volume fraction of CO in the reformed gas supplied to the hydrogen storage alloy increases, the total amount of hydrogen stored in the hydrogen storage alloy decreases and the amount of CO slightly increases in the hydrogen released from the hydrogen storage alloy. Although a small amount is included, when hydrogen containing CO is supplied to the fuel cell, there is a problem in that the power generation output of the fuel cell decreases.
JP 2000-12061 A JP 2000-327306 A

  The present invention has been made in view of the above points, and in a fuel cell power generation system including a reformed gas generation unit, a hydrogen storage alloy, and a fuel cell, prevents deterioration of the hydrogen storage alloy due to impurity gas in the reformed gas. At the same time, it is an object of the present invention to provide a fuel cell power generation system capable of preventing a decrease in power generation output of the fuel cell due to CO.

  A fuel cell power generation system according to claim 1 of the present invention includes a reformed gas generation unit 1 that generates a reformed gas mainly composed of hydrogen by steam reforming a hydrocarbon-based fuel, and the generated reformed gas. A gas separation membrane 2 for passing and increasing the volume fraction of hydrogen in the reformed gas to reduce the volume fraction of CO, and a hydrogen storage alloy 3 to which the reformed gas that has passed through the gas separation membrane 2 is supplied , A fuel cell power generation system including a fuel cell 4 that generates power using hydrogen stored in the hydrogen storage alloy 3, wherein the gas separation membrane 2 is substantially free of noble metal, and the hydrogen storage alloy 3 Is characterized in that it has been subjected to surface modification treatment for suppressing poisoning of CO.

  The invention of claim 2 is characterized in that in claim 1, the gas separation membrane is a ceramic membrane.

  The invention of claim 3 is characterized in that, in claim 1 or 2, the surface modification treatment of the hydrogen storage alloy 3 is a fluorination treatment.

  The invention of claim 4 is characterized in that, in any one of claims 1 to 3, the reformed gas generator 1 does not include a CO conversion process of a CO shift reaction and a CO selective oxidation reaction. .

  According to a fifth aspect of the present invention, in the fuel cell power generation system according to any of the first to fourth aspects, before the hydrogen occluded in the hydrogen occlusion alloy 3 is released, the hydrogen occlusion alloy 3 is pressurized and heated. At least one of these operations is performed.

  A sixth aspect of the invention is characterized in that, in any one of the first to fifth aspects, a substance having catalytic activity is added to the hydrogen storage alloy 3.

  According to the fuel cell power generation system according to claim 1 of the present invention, since the gas separation membrane 2 is substantially free of noble metal, it is possible to suppress the performance deterioration of impurity gas reduction due to pinhole expansion or the like. In addition, since the hydrogen storage alloy 3 has been subjected to a surface modification treatment for suppressing poisoning of CO, the deterioration of the hydrogen storage alloy 3 is prevented and the performance deterioration of the impurity gas reduction is suppressed. It is something that can be done. As a result, it is possible to obtain a fuel cell power generation system that prevents a decrease in power generation output of the fuel cell 4 due to CO, has high power generation efficiency, and high reliability.

  The invention of claim 2 uses a ceramic membrane as the gas separation membrane, so that the separation factor between hydrogen and impurity gas is high, the CO contained in the reformed gas is sufficiently reduced, and the hydrogen storage alloy is deteriorated by the impurity gas. Thus, a more reliable fuel cell power generation system can be obtained.

  In the invention of claim 3, since the surface modification treatment of the hydrogen storage alloy 3 is a fluorination treatment, it is possible to sufficiently suppress the poisoning of CO and prevent deterioration of the hydrogen storage alloy due to impurity gas, A more reliable fuel cell power generation system can be obtained.

  In the invention of claim 4, since the reformed gas generation unit 1 does not include a CO conversion process of a CO shift reaction and a CO selective oxidation reaction, the system can be simplified and the cost can be reduced.

  In the invention of claim 5, since at least one of pressurization and heating of the hydrogen storage alloy 3 is performed before releasing the hydrogen stored in the hydrogen storage alloy 3, the hydrogen storage alloy 3 is changed into a fuel cell. CO contained in the supplied hydrogen can be reduced, and a decrease in the power generation output of the fuel cell 4 can be prevented.

  In the invention of claim 6, since a substance having catalytic activity is added to the hydrogen storage alloy 3, CO contained in hydrogen supplied to the fuel cell 4 can be further reduced. It is possible to prevent a decrease in output.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 is a schematic diagram showing an example of a fuel cell power generation system according to the present invention, in which a reformed gas generation unit 1 for reforming a hydrocarbon-based fuel by steam reforming to generate a reformed gas mainly composed of hydrogen, The volume fraction of hydrogen is increased by the gas separation membrane 2 and the gas separation membrane 2 for increasing the volume fraction of hydrogen in the reformed gas generated in the gas generator 1 and sufficiently reducing CO in the reformed gas. The fuel cell power generation system includes a hydrogen storage alloy 3 for storing hydrogen in the improved reformed gas, and a fuel cell 4 for generating power using the hydrogen stored in the hydrogen storage alloy 3.

  In the embodiment of FIG. 1, dimethyl ether is used as the hydrocarbon-based fuel, and is supplied to the reformed gas generator 1 together with water by the liquid feed pump 10. As the reformed gas generation unit 1, one having only a reforming unit that causes a steam reforming reaction of a hydrocarbon-based fuel can be used. As will be described later, in this system, the gas separation membrane 2 is used to sufficiently reduce the CO in the reformed gas, so that the reforming does not include a CO conversion process such as a CO shift reaction or a CO selective oxidation reaction. The gas generation unit 1 can be used, and the system can be simplified and the cost can be reduced. The reformed gas generated by the reformed gas generator 1 contains about 1% of CO in volume fraction.

  As the gas separation membrane 2, a ceramic membrane such as a silica membrane can be used. The ceramic membrane used as the gas separation membrane 2 is one that does not substantially contain a noble metal such as Pd. By using a ceramic film that does not substantially contain a noble metal such as Pd as described above, it is possible to prevent the performance deterioration of impurity gas reduction due to pinhole expansion or the like. The phrase “substantially no precious metal” means that it is allowed to be contained in such a small amount that pinhole expansion does not occur. Here, the reformed gas generated in the reformed gas generator 1 usually contains a high temperature and a large amount of unreacted moisture, but the separation performance of ceramic membranes such as silica membranes deteriorates due to high temperatures and heat cycles. Easily, the separation factor is lowered due to the moisture content, and the separation performance deteriorates. Therefore, in the embodiment of FIG. 1, a moisture cooling aggregator 11 including a moisture cooler and a moisture condensing / recovering device is provided between the reformed gas generator 1 and the gas separation membrane 2, and the reformed gas generator 1 The reformed gas generated in step 1 is passed through the moisture cooling condenser 11 to be cooled and recovered, and then sent to the gas separation membrane 2. The moisture recovered by the moisture cooling aggregator 11 can be reused for the humidification of the electrolyte membrane of the fuel cell 4 and the supply water for the steam reforming reaction.

When the reformed gas whose temperature is appropriately lowered by the moisture cooling aggregator 11 is passed through the gas separation membrane 2 formed of a ceramic membrane such as a silica membrane, the gas separation membrane 2 is CO, CO ₂ , CH _4. Since hydrogen permeation performance is higher than impurity gases such as, the volume fraction of hydrogen in the reformed gas can be increased, and the volume fraction of CO can be reduced to 0.1% or less. It can be done. At this time, since the liquid feed pump 10 is used as a hydrocarbon fuel and water supply device, the pressure on the primary side of the gas separation membrane 2 is increased by a small pump power and efficient volume expansion accompanying heating and reaction. Therefore, it is possible to sufficiently increase the flow rate when separating hydrogen and impurity gas in the gas separation membrane 2. Therefore, the area of the gas separation membrane 2 can be reduced, the volume fraction of CO of the reformed gas can be efficiently reduced, and the hydrogen recovery rate in the hydrogen storage alloy 3 can be increased. It is something that can be done. Impurity gases such as CO, CO ₂ , and CH ₄ that do not pass through the gas separation membrane 2 are recovered by the recovery device 25.

Further, as the hydrogen storage alloy 3, for example, an AB5 type LmNi alloy (lanthanum rich misch metal / nickel alloy: one having a hydrogen equilibrium pressure at room temperature greater than 0.1 MPa) can be used. The surface of the hydrogen storage alloy 3 is subjected to surface modification treatment for suppressing poisoning by CO. The surface modification treatment can be performed, for example, by fluorination treatment that forms a fluoride film on the surface of the hydrogen storage alloy 3. The fluorination treatment is performed, for example, by flowing a fluorine gas (F ₂ ) or a fluorine gas diluted with an inert gas for a predetermined time into a container enclosing the hydrogen storage alloy 3 at a predetermined temperature of about 150 ° C. The dry method of forming a fluorine film on the surface of the alloy 3 or the powder of the hydrogen storage alloy 3 is immersed in a hydrofluoric acid solution for a predetermined time and stirred, and then the hydrogen storage alloy 3 and the solution are separated. Thereafter, it can be carried out by any method such as a wet method in which heating is performed in an inert gas at a predetermined temperature of 150 ° C. or lower.

  A temperature controller 12 is connected to the hydrogen storage alloy 3 so that the hydrogen storage alloy 3 can be cooled and heated, and an on-off valve 13 is provided between the hydrogen storage alloy 3 and the gas separation membrane 2. An open / close valve 14 is provided between the hydrogen storage alloy 3 and the fuel cell 4. Further, a switching valve 15 is provided between the on-off valve 14 and the fuel cell 4. The switching valve 15 switches whether the flow path from the hydrogen storage alloy 3 is circulated to the fuel cell 4 side or to the collector 26 side. Then, when the reformed gas having a reduced volume fraction of CO is supplied from the gas separation membrane 2 to the hydrogen storage alloy 3 by opening the on-off valve 13, the hydrogen storage alloy 3 is cooled by the temperature controller 12, Hydrogen of the reformed gas is stored in the hydrogen storage alloy 3. Since the hydrogen storage alloy 3 selectively stores hydrogen, when the on-off valve 14 is opened and the switching valve 15 is switched to the recovery device 26 side, impurity gases such as CO other than hydrogen can be recovered in the recovery device 26. it can. Further, when the fuel cell 4 generates power, the hydrogen storage alloy 3 is heated by the temperature controller 12 so that hydrogen can be released from the hydrogen storage alloy 3. The on-off valve 14 is opened and the switching valve 15 is operated as a fuel. By switching to the battery 4 side, only hydrogen is supplied to the fuel cell 4 and power generation by the fuel cell 4 can be performed efficiently. The hydrogen storage and release in the hydrogen storage alloy 3 may be switched according to the power generation load of the fuel cell 4. The impurity gas recovered from the gas separation membrane 2 as described above and the impurity gas recovered from the hydrogen storage alloy 3 as described above contain a small amount of unrecovered hydrogen in addition to harmful combustible CO. It can be easily combusted and can be used as a heat source for the steam reforming reaction in the reformed gas generator 1.

  Here, since the surface of the hydrogen storage alloy 3 is subjected to a surface modification treatment such as a fluorination treatment, a small amount of CO is contained in the reformed gas supplied from the gas separation membrane 2 to the hydrogen storage alloy 3. Even so, the effect of CO on the hydrogen storage alloy 3 can be blocked by the coating formed by the surface modification treatment, and the deterioration of the hydrogen storage alloy 3 due to poisoning due to the action of CO can be prevented. It can be done. The surface modification treatment of the hydrogen storage alloy 3 may be a treatment other than the fluorination treatment as long as it can coat a film of a substance capable of obtaining poisoning resistance to CO.

  Further, after such surface modification treatment, a metal having catalytic activity for methanation reaction, shift reaction, selective oxidation reaction, such as Pt or Pd, may be added to the surface of the hydrogen storage alloy 3. . The metal can be added by mixing metal powder into the hydrogen storage alloy 3, depositing metal on the surface of the hydrogen storage alloy 3 by plating or vapor deposition, or the surface of the hydrogen storage alloy 3 in the form of an organic complex. It can be carried out by an arbitrary method such as a method in which an organic substance is removed by heat treatment.

  Further, when hydrogen is released from the hydrogen storage alloy 3 and supplied to the fuel cell 4 as described above, if the volume fraction of CO contained in the reformed gas supplied to the hydrogen storage alloy 3 is high, the hydrogen storage alloy The hydrogen released from 3 may contain a small amount of CO. Therefore, a method for reducing CO contained in hydrogen will be described below. Before releasing hydrogen from the hydrogen storage alloy 3, the inlet and outlet of the hydrogen storage alloy 3 are closed by the on-off valve 13 and the on-off valve 14. When the hydrogen storage alloy 3 is heated in this state, the physical properties of the hydrogen storage alloy 3 The hydrogen equilibrium pressure increases due to the characteristics. Thus, by pressurizing the hydrogen storage alloy 3 while heating, the methanation reaction of CO by the catalytic action of a metal such as Ni contained in the hydrogen storage alloy 3 or the transformation reaction with water contained in a trace amount is promoted. The CO in the storage alloy 3 can be reduced, and the CO contained in the hydrogen released from the hydrogen storage alloy 3 can be sufficiently reduced. Although it is desirable to pressurize the hydrogen storage alloy 3 while heating, it may be either heating or pressurization. A means for reducing the CO concentration may be added as a process before and after the hydrogen storage alloy 3. Further, by adjusting the temperature condition and pressure condition of the container containing the hydrogen storage alloy 3 appropriately without going through the heating and pressurizing processes as described above, the methanation reaction and the metamorphic reaction proceed, and at the same time the CO concentration May be reduced. In this case, it is necessary to select an alloy material having an appropriate characteristic that ensures a sufficient occlusion speed under the set conditions. It is also effective to promote the reduction of the CO concentration by keeping the container storing the hydrogen storage alloy 3 during the exothermic reaction during hydrogen storage, using a pressure holding valve, or the like.

  FIG. 2 shows another embodiment of the present invention, in which the hydrogen storage alloy 3 having the configuration of FIG. 2 is used in place of the configuration of the hydrogen storage alloy 3 of the system of FIG. In the embodiment of FIG. 2, two hydrogen storage alloys 3a and 3b are used as the hydrogen storage alloy 3, and between the first and second hydrogen storage alloys 3a and 3b. A heat exchange device 17 is provided. A switching valve 19 is provided in the inflow channel 18 led out from the gas separation membrane 3, and the switching valve 19 branches the inflow channel 18 into a first inflow channel 18a and a second inflow channel 18b. The flow path 18a is connected to the first hydrogen storage alloy 3a, and the second inflow flow path 18b is connected to the second hydrogen storage alloy 3b. In addition, a switching valve 21 is provided in the first discharge flow path 20 derived from the first hydrogen storage alloy 3 a, and the first discharge flow path 20 is connected to the recovery device 27 by the switch valve 21. It branches off to a supply flow path 20b connected to the fuel cell 4. Furthermore, the switching valve 23 is provided in the 2nd discharge path 22 derived | led-out from the 2nd hydrogen storage alloy 3b, the 2nd discharge flow path 22 is connected by the switch valve 23 with the collection | recovery flow path 22a connected to the recovery device 28, and fuel. It branches off to a supply flow path 22 b connected to the battery 4. In the embodiment of FIG. 2, the supply flow path 20 b and the supply flow path 22 b are joined and connected to the fuel cell 4.

  In this case, as shown in FIG. 2A, the switching valve 19 is switched to connect the flow path from the inflow path 18 to the second inflow path 18b and to the first inflow path 18a. The switching valve 21 is switched to connect the flow path from the first discharge flow path 20 to the supply flow path 20b, the flow path to the recovery flow path 20a is blocked, and the switching valve 23 is switched to 2 The flow path from the discharge flow path 22 to the supply flow path 22b is blocked and the flow path to the recovery flow path 22a is communicated (the flow path communicating in FIG. 2 is indicated by a solid line, and the flow path to be blocked is indicated by a broken line). When the respective channels are switched in this way, the hydrogen stored in the first hydrogen storage alloy 3a is supplied from the first release channel 20 to the fuel cell 4 through the supply channel 20b. At the same time, the reformed gas generated in the reformed gas generator 1 and permeated through the gas separation membrane 2 is supplied from the inflow channel 18 through the second inflow channel 18b to the second hydrogen storage alloy 3b and stored. Impurity gases other than hydrogen, such as CO, are recovered from the second discharge channel 22 to the recovery device 28 through the recovery channel 22a. Further, as shown in FIG. 2B, the switching valve 19 is switched to connect the flow path from the inflow flow path 18 to the first inflow flow path 18a and the flow path to the second inflow flow path 18b is shut off. Further, the switching valve 21 is switched to connect the flow path from the first discharge flow path 20 to the supply flow path 20b, the flow path to the recovery flow path 20a is shut off, and the switching valve 23 is further switched to switch the second discharge flow path. The flow path from 22 to the supply flow path 22b is communicated and the flow path to the recovery flow path 22a is blocked. When the respective flow paths are switched in this way, hydrogen stored in the second hydrogen storage alloy 3b is supplied from the second discharge flow path 22 to the fuel cell 4 through the supply flow path 22b. At the same time, the reformed gas generated in the reformed gas generator 1 and permeated through the gas separation membrane 2 is supplied from the inflow channel 18 to the first hydrogen storage alloy 3a through the first inflow channel 18a and stored. Impurity gases other than hydrogen, such as CO, are recovered from the first discharge flow channel 20 to the recovery device 27 through the recovery flow channel 20a.

  In this way, while hydrogen is discharged from the first hydrogen storage alloy 3a to the fuel cell 4 to generate power, the hydrogen of the reformed gas generated in the reformed gas generation unit 1 is stored in the second hydrogen storage alloy 3b. When the hydrogen storage amount of the first hydrogen storage alloy 3a is reduced, hydrogen is released from the second hydrogen storage alloy 3b to the fuel cell 4 to generate power, and is generated in the reformed gas generation unit 1. The hydrogen of the reformed gas can be stored in the first hydrogen storage alloy 3a, and the first hydrogen storage alloy 3a and the second hydrogen storage alloy 3b are stored and released by the switching operation of the switching valves 19, 21, 23. By alternately switching the gas, hydrogen is continuously supplied from the hydrogen storage alloy 3 to the fuel cell 4 while generating the reformed gas continuously from the reformed gas generator 1, and stable for a long time. That can drive the system. That.

  Here, since the heat exchange device 17 is provided between the first hydrogen storage alloy 3a and the second hydrogen storage alloy 3b, one of the first and second hydrogen storage alloys 3a, 3b is one of the hydrogen storage alloys 3a. , 3b can be used as heat for releasing hydrogen from the other hydrogen storage alloys 3a, 3b, and by using the heat generated by the storage of hydrogen. The hydrocarbon fuel and water supplied to the reformed gas generator 1 can be preheated. Further, the exhaust heat of the fuel cell 4 can be used as heat necessary for releasing hydrogen from the hydrogen storage alloys 3a and 3b by the heat exchange device 17, and energy saving can be achieved. . In the embodiment of FIG. 2, two hydrogen storage alloys 3 are provided, but the number of hydrogen storage alloys 3 may be two or more, and the number is not particularly limited.

  The present invention is not limited to the above embodiments. For example, as the hydrocarbon fuel, in addition to the above dimethyl ether, other liquid fuels such as methanol and ethanol may be used, or gaseous fuels such as methane and propane may be used. Further, in the reforming reaction in the reformed gas generation unit 1, not only a steam reforming reaction but also a catalytic combustion combined reforming apparatus such as a partial oxidation reaction or autothermal can be applied. When a gaseous fuel is used as the hydrocarbon-based fuel, it may be necessary to increase the pressure on the primary side of the gas partial pressure film by supplying the fuel to the reformed gas generator 1 with a compressor.

  Further, when a ceramic membrane is used as the gas separation membrane 2, it is sufficient if a necessary separation factor such as a zeolite membrane or a zirconia membrane is ensured in addition to the silica membrane as described above. In particular, the ceramic film is characterized in that a large amount of gas permeation can be obtained with a relatively low differential pressure, which is effective in improving the efficiency of the entire system. When the reforming temperature of the reformed gas generator 1 is relatively low, the volume fraction of CO contained in the reformed gas is low. Therefore, a polymer membrane such as polyimide is used as the gas separation membrane 2. In addition, CO contained in the reformed gas supplied to the hydrogen storage alloy 3 can be sufficiently reduced. Since the polymer film is less expensive than the ceramic film, the cost of the system can be reduced. In addition, when the ability to resist CO poisoning is sufficiently obtained by the surface modification treatment of the hydrogen storage alloy 3, the gas separation membrane itself is not necessary.

  Further, as the hydrogen storage alloy 3, in addition to the above LmNi alloy, a LaNi alloy, a Ti alloy (for example, TiFe0.85Mn0.15) or the like can be used. In addition to hydrogen storage alloys, materials that can selectively store only hydrogen, such as organic, inorganic, and carbon-based hydrogen storage materials that have been surface-modified for resistance to poisoning, are also resistant. If the material is strong, it can be used.

  As a means for storing and releasing hydrogen in the hydrogen storage alloy 3, the storage of hydrogen is performed by relatively high pressure, natural or forced cooling, the release of hydrogen is performed at room temperature, and the storage of hydrogen is performed at normal pressure.・ Natural or forced cooling and release with relatively high temperature heating, or hydrogen occlusion with relatively low pressure and natural or forced cooling and release with relatively low temperature heating, etc. By adjusting the composition of the hydrogen storage alloy 3, various conditions can be selected, and appropriate system characteristics can be provided according to required specifications such as emphasis on load following and efficiency. It is.

It is the schematic which shows an example of embodiment of this invention. It shows an example of another embodiment of the above, and (a) and (b) are schematic diagrams respectively. It is the schematic which shows an example of the past. It is the schematic which shows another example of the past. It is the schematic which shows another example of the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reformed gas production | generation part 2 Gas separation membrane 3 Hydrogen storage alloy 4 Fuel cell

Claims (6)

  A reformed gas generation unit that generates a reformed gas mainly composed of hydrogen by steam reforming a hydrocarbon fuel, and the generated reformed gas is allowed to pass through to increase the hydrogen volume fraction of the reformed gas. A gas separation membrane for reducing the volume fraction of CO, a hydrogen storage alloy to which the reformed gas that has passed through the gas separation membrane is supplied, and a fuel cell that generates power using hydrogen stored in the hydrogen storage alloy A fuel cell power generation system provided with a gas separation membrane that does not substantially contain a noble metal, and a hydrogen storage alloy that has been subjected to a surface modification treatment for suppressing poisoning of CO. A fuel cell power generation system.   The fuel cell power generation system according to claim 1, wherein the gas separation membrane is a ceramic membrane.   The fuel cell power generation system according to claim 1 or 2, wherein the surface modification treatment of the hydrogen storage alloy is a fluorination treatment.   4. The fuel cell power generation system according to claim 1, wherein the reformed gas generation unit does not include a CO conversion process of a CO shift reaction and a CO selective oxidation reaction.   5. The fuel cell power generation system according to claim 1, wherein at least one of pressurization and heating of the hydrogen storage alloy is performed before releasing the hydrogen stored in the hydrogen storage alloy. The fuel cell power generation system according to any one of the above. 6. The fuel cell power generation system according to claim 1, wherein a substance having catalytic activity is added to the hydrogen storage alloy.

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