JP2006107946A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system preventing deposition of carbon on a reforming part. <P>SOLUTION: The fuel cell system is provided with: a reformer 3 generating reformed gas containing hydrogen by reforming a hydrocarbon based fuel by a steam reforming reaction; a steam separating film 13 separating at least one part of steam in the reformed gas; and bypassing means (110, 111, 112) introducing the steam separated by the steam separating film 13 into the reformer 3. The reformed gas containing hydrogen is formed from the hydrocarbon based fuel by the reformer, at least one part of the steam in the reformed gas is separated by the steam separating film, and the separated steam is introduced into the reformer by the bypass means. Shortage of the steam in the reformer is prevented thereby. As a result, deposition of carbon in the reformer is prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell system including a reforming unit that generates a reformed gas used for fuel of a fuel cell from a hydrocarbon-based fuel.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. This fuel cell has been developed widely as a future energy supply system because it is environmentally friendly and can realize high energy efficiency.

  Currently, in many fuel cells, a reformed gas containing hydrogen is generated from a hydrocarbon-based fuel such as gasoline, natural gas, or methanol by a reforming unit, and supplied to the anode of the fuel cell. In this reforming section, reforming is performed by a steam reforming reaction using steam or the like (for example, see Patent Document 1).

  In recent years, a technique for providing a reformed gas generated by the reforming unit to a spark ignition engine has been disclosed (see, for example, Patent Document 2). According to this technique, one or both of hydrogen in gasoline and reformed gas can be used as a fuel for a spark ignition engine, and high thermal efficiency can be obtained.

  However, in order to generate the reformed gas by the steam reforming reaction, it is necessary to newly provide means for supplying steam to the reforming section. Therefore, the fuel cell is increased in size.

In order to solve this problem, a technique for introducing a cathode off-gas discharged from the cathode into the reforming section has been disclosed (for example, see Patent Document 3). According to this technique, since the water vapor contained in the cathode off gas can be supplied to the reforming section, there is no need to newly provide a water vapor generator or the like. As a result, the fuel cell can be reduced in size.
JP 7-215701 A JP 11-311136 A JP 2000-195534 A

  However, when hydrogen is supplied to the spark ignition engine, the amount of hydrogen supplied to the fuel cell decreases. Thereby, the amount of water vapor in the gas discharged from the fuel cell is reduced. Therefore, it becomes impossible to supply steam necessary for the steam reforming reaction to the reforming section. As a result, the steam reforming reaction may not be completed and carbon may be deposited in the reforming part.

  This invention is made | formed in view of the said subject, and it aims at providing the fuel cell system which can prevent precipitation of carbon in a reforming part.

  The system according to the present invention includes a reforming means for reforming a hydrocarbon fuel by a steam reforming reaction to generate a reformed gas containing hydrogen, and a steam separation for separating at least a part of the steam in the reformed gas. And a bypass means for introducing the water vapor separated by the water vapor separation means into the reforming means.

  In the system according to the present invention, a reformed gas containing hydrogen is generated from the hydrocarbon fuel by the reforming means, and at least a part of the water vapor in the reformed gas is separated by the steam separation means, and the separated steam is It is introduced into the reforming means by the bypass means. Therefore, a shortage of water vapor in the reforming means is prevented. As a result, carbon deposition in the reforming means can be prevented.

  You may further provide the flow volume adjustment means which adjusts the flow volume of the water vapor | steam which flows through a bypass means, and the control means which controls a flow volume adjustment means so that the flow volume of the water vapor | steam which flows through a bypass means may be adjusted. In this case, the amount of water vapor supplied to the reforming means can be adjusted according to the amount of water vapor in the reforming means.

  A buffer for storing water vapor may be provided in the bypass means. In this case, the water vapor separated by the water vapor separation means can be temporarily stored.

  A fuel cell that generates power using hydrogen and oxygen, and an off-gas supply unit that supplies off-gas containing moisture discharged from the fuel cell to the reforming unit may be further provided. In this case, water vapor generated in the fuel cell can be used for the steam reforming reaction. Thereby, it is not necessary to newly provide a water vapor supply means. As a result, the system according to the present invention can be reduced in size.

  A power unit driven by at least a part of the reformed gas and / or a hydrocarbon-based fuel, a reformed gas supply unit that supplies the power unit with an amount of reformed gas necessary for the operation of the power unit, and a reforming unit Fuel supply means for supplying hydrocarbon fuel, and the control means controls the fuel supply means to adjust the amount of hydrocarbon fuel supplied to the reforming means in accordance with the amount of reformed gas supplied to the power unit. May be controlled.

  In this case, the power unit can be operated with high thermal efficiency by the combination of hydrogen in the reformed gas and hydrocarbon fuel. Further, by providing the fuel cell and the power unit, it is possible to combine either one or both of the electric power generated from the fuel cell and the power generated from the power unit. Thereby, an appropriate external output according to the operation status of the system according to the present invention is possible.

  The control means may fully close the flow rate adjusting means when the reformed gas is not supplied to the power section. In this case, the supply of water vapor to the reforming means does not become excessive. Thereby, it is possible to prevent a decrease in efficiency in generating the reformed gas.

  The power unit may be an internal combustion engine. In this case, the fuel cell system according to the present invention can be applied to a hybrid vehicle or the like. As a result, the thermal efficiency can be improved by selecting the power according to the operating condition.

  The water vapor separation means may be an ion exchange resin that selectively permeates water vapor in the gas. In this case, water vapor in the reformed gas can be efficiently separated.

  According to the present invention, insufficient steam in the reforming unit is prevented. As a result, carbon deposition in the reforming means can be prevented.

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

  FIG. 1 is a schematic diagram showing the overall configuration of a fuel cell system 100 according to the present invention. As shown in FIG. 1, the fuel cell system 100 includes a fuel tank 1, injectors 2 and 11, a reformer 3, heat exchangers 4 and 7, a fuel cell 5, air pumps 6 and 8, a flow control valve 9, an internal combustion engine. 10, a control unit 12, a water vapor separation membrane 13, and a water vapor flow rate control valve 14 are included. The reformer 3 includes a reforming unit 3a and a combustion unit 3b. The fuel cell 5 is a hydrogen separation membrane cell, and includes an anode 5a and a cathode 5b.

  Here, the hydrogen separation membrane battery is a fuel cell provided with a hydrogen separation membrane layer. The hydrogen separation membrane layer is a layer formed of a metal having hydrogen permeability, and can be formed of, for example, palladium, a palladium alloy, or the like. The hydrogen separation membrane battery has a structure in which the hydrogen separation membrane layer and an electrolyte having proton conductivity are laminated. Hydrogen supplied to the anode of the hydrogen separation membrane battery is converted into protons via a catalyst, moves through proton conductive electrolyte, and combines with oxygen at the cathode to become water. Therefore, most of the water or water vapor generated from the fuel cell 5 is contained in the cathode offgas. The operating temperature of the hydrogen separation membrane battery is about 300 ° C to 600 ° C.

  The fuel tank 1 is connected to the injector 2 via a pipe 101. The injector 2 is connected to the reforming unit 3a. The reforming unit 3a is connected to the anode 5a via the pipe 102. A part of the pipe 102 passes through the heat exchanger 4. The anode 5a is connected to the combustion unit 3b via the pipe 103.

  One end of the pipe 110 is connected to the upstream side of the heat exchanger 4 of the pipe 102, and the other end of the pipe 110 is connected to the water vapor separation membrane 13. The water vapor separation membrane 13 is connected to the water vapor flow rate control valve 14 through a pipe 111. The steam flow rate control valve 14 is connected to the middle of the pipe 105 through the pipe 112.

  The air pump 8 is connected to the cathode 5b through the pipe 104. A part of the pipe 104 passes through the heat exchanger 7 and the heat exchanger 4. The cathode 5b is connected to the reforming unit 3a via the pipe 105. The air pump 6 is connected to the combustion unit 3b via a pipe 106. A part of the pipe 106 passes through the fuel cell 5.

  One end of the pipe 107 is connected upstream of the heat exchanger 4 of the pipe 102 and downstream of the branch point with the pipe 110, and the other end of the pipe 107 is connected to the flow control valve 9. A part of the pipe 107 passes through the heat exchanger 7. The flow control valve 9 is connected to the internal combustion engine 10 via a pipe 108. The fuel tank 1 is connected to the injector 11 via a pipe 109. The injector 11 is connected to the internal combustion engine 10.

  Next, the operation of the fuel cell system 100 will be described. In the fuel tank 1, gasoline is stored as a hydrocarbon fuel. The fuel tank 1 supplies a required amount of gasoline to the injector 2 via the pipe 101 in accordance with an instruction from the control unit 12. The injector 2 supplies a required amount of gasoline to the reforming unit 3a according to an instruction from the control unit 12.

  In the reforming unit 3a, reformed gas is generated by the gasoline supplied from the injector 2 and a cathode off gas described later. First, a steam reforming reaction occurs between the gasoline supplied from the injector 2 and the steam in the cathode off gas, and hydrogen and carbon monoxide are generated. Next, a part of the generated carbon monoxide reacts with the water vapor in the cathode offgas, and hydrogen and carbon dioxide are generated. When the steam required for the steam reforming reaction is insufficient, oxygen and carbon monoxide in the cathode off-gas cause a partial oxidation reaction via the catalyst in the reforming section 3a to generate carbon dioxide. .

  The reformed gas generated in the reforming unit 3a is cooled by the air flowing through the pipe 104 in the heat exchanger 4 and supplied to the anode 5a. In the anode 5a, hydrogen in the reformed gas is converted into hydrogen ions. Hydrogen that has not been converted into hydrogen ions at the anode 5a and carbon monoxide that has not reacted at the reforming unit 3a are supplied to the combustion unit 3b through the pipe 103 as an anode off-gas, and in the air supplied from the pipe 106 It burns with oxygen and is discharged outside the fuel cell system 100. The combustion heat at this time is used for the steam reforming reaction in the reforming unit 3a.

  Thus, since the combustion heat using the anode off gas as fuel is used for the steam reforming reaction in the reforming unit 3a, it is not necessary to newly provide a fuel tank for combustion. Thereby, the fuel cell system 100 can be reduced in size. Incomplete combustion components such as carbon monoxide contained in the anode off gas can be completely burned in the combustion section 3b. Thereby, environmental pollution can be prevented.

  The air pump 8 supplies air from the outside of the fuel cell system 100 to the pipe 104 in accordance with instructions from the control unit 12. This air cools the reformed gas flowing through the pipe 107 in the heat exchanger 7, then cools the reformed gas flowing through the pipe 102 in the heat exchanger 4, and is supplied to the cathode 5 b. In the cathode 5b, water is generated and electric power is generated from hydrogen ions generated in the anode 5a and oxygen in the air supplied to the cathode 5b. The generated water becomes water vapor by the heat generated in the fuel cell 5. The water vapor generated at the cathode 5b is supplied to the reforming unit 3a through the pipe 105 as a cathode off gas and used for the water vapor reforming reaction.

  Thus, since the steam generated in the cathode 5b is used for the steam reforming reaction, it is not necessary to newly provide a steam supply means. Thereby, the fuel cell system 100 can be reduced in size.

  The air pump 6 supplies air from the outside of the fuel cell system 100 to the pipe 106 in accordance with instructions from the control unit 12. The air flowing through the pipe 106 cools the fuel cell 5, is supplied to the combustion unit 3b, and is used for combustion of hydrogen and carbon monoxide in the anode off-gas. Thus, since the cooling air of the fuel cell 5 is used for combustion in the combustion section 3b, it is not necessary to newly provide oxygen supply means for burning the anode off gas. Thereby, the fuel cell system 100 can be reduced in size.

  A part of the reformed gas supplied to the pipe 102 is supplied to the pipe 110. The reformed gas supplied to the pipe 110 is supplied to the water vapor separation membrane 13. The water vapor separation membrane 13 is made of a water vapor permeable ion exchange resin or the like, and selectively supplies water vapor in the reformed gas to the pipe 111. As the water vapor permeable ion exchange resin, for example, a resin such as a polyester polyether nonporous resin can be used. The water vapor supplied to the pipe 111 is supplied to the water vapor flow rate control valve 14. The steam flow rate control valve 14 supplies a necessary amount of steam to the pipe 112 in accordance with an instruction from the control unit 12. The water vapor supplied to the pipe 112 is supplied to the reforming unit 3 a via the pipe 105. Details of supplying water vapor from the pipe 112 to the pipe 105 will be described later.

  As described above, since the steam that has not been used for the steam reforming reaction in the reforming unit 3a is supplied again to the reforming unit 3a, the lack of steam in the reforming unit 3a is prevented. As a result, carbon deposition in the reforming part 3a is prevented.

  A part of the reformed gas supplied to the pipe 102 is supplied to the pipe 107, cooled by the air flowing through the pipe 104 in the heat exchanger 7, and supplied to the flow control valve 9. The flow control valve 9 supplies a required amount of reformed gas to the internal combustion engine 10 via the pipe 108 in accordance with instructions from the control unit 12. Further, the fuel tank 1 supplies a required amount of gasoline to the injector 11 via the pipe 109 in accordance with an instruction from the control unit 12. The injector 11 supplies a required amount of gasoline to the internal combustion engine 10 in accordance with an instruction from the control unit 12.

  Thus, since the reformed gas cooled in the heat exchanger 7 is supplied to the internal combustion engine 10, thermal damage or thermal deterioration of the internal combustion engine 10 can be prevented. For example, by cooling the reformed gas to 100 ° C. or lower, it is possible to prevent thermal damage or deterioration of an intake system gasket, electrical components, electrical wiring, and the like built in the internal combustion engine 10.

  The internal combustion engine 10 operates by creating an air-fuel mixture at a predetermined air-fuel ratio from at least a part of the reformed gas and / or gasoline and air in accordance with instructions from the control unit 12 and burning the air-fuel mixture. In this case, the internal combustion engine 10 can be operated with high thermal efficiency by a combination of hydrogen and gasoline.

  Further, when hydrogen is not supplied to the internal combustion engine 10, the control unit 12 controls the air-fuel ratio of the internal combustion engine 10 according to a base map created in advance. When supplying hydrogen to the internal combustion engine 10, the control unit 12 controls the air-fuel ratio of the internal combustion engine 10 so as to perform lean combustion corresponding to the amount of hydrogen supplied to the internal combustion engine 10. In this case, the lean limit can be expanded according to the proportion of hydrogen supplied to the internal combustion engine 10. For example, by supplying gasoline and hydrogen to the internal combustion engine 10 so that the combustion heat of gasoline supplied to the internal combustion engine 10 is five times the combustion heat of hydrogen supplied to the internal combustion engine 10, an excess air ratio ( The ratio to the stoichiometric air / fuel ratio can be increased to about 2. Thereby, gasoline consumption is reduced and nitrogen oxide emissions are reduced.

  By providing the fuel cell 5 and the internal combustion engine 10 as in the fuel cell system 100 according to the present invention, either or both of electric power generated from the fuel cell 5 and power generated from the internal combustion engine 10 can be combined. As a result, an appropriate external output according to the operation status of the fuel cell system 100 is possible.

  FIG. 2 is a schematic diagram for explaining how water vapor flowing through the pipe 112 is supplied to the pipe 105. As shown in FIG. 2, an orifice portion 105 a having a narrow flow path is provided in the middle of the pipe 105. The pipe 112 is connected to the orifice portion 105a. The flow rate of the cathode off gas flowing through the pipe 105 increases rapidly at the orifice portion 105a. As a result, water vapor flowing through the pipe 112 is sucked into the pipe 105 by the ejector effect. From the above, the steam supplied from the steam flow rate control valve 13 of FIG. 1 to the pipe 112 is supplied to the reforming unit 3a via the pipe 105.

  FIG. 3 is a map used when the control unit 12 controls the air pump 8, the flow control valve 9, the internal combustion engine 10, and the injector 11. FIG. 3A is a map showing the relationship between the amount of air supplied by the air pump 8 and the pump rotation speed of the air pump 8. The vertical axis in FIG. 3A indicates the pump rotation speed of the air pump 8, and the horizontal axis in FIG. 3A indicates the amount of air supplied by the air pump 8. As shown in FIG. 3A, the pump rotational speed of the air pump 8 increases in proportion to the square of the air supply amount of the air pump 8. The control unit 12 controls the air pumps 6 and 8 based on the map of FIG.

  FIG. 3B is a map showing an example of the relationship between the rotational speed of the internal combustion engine 10, the torque of the internal combustion engine 10, and the excess air ratio λ. The vertical axis in FIG. 3B indicates the torque of the internal combustion engine 10, and the horizontal axis in FIG. 3B indicates the rotational speed of the internal combustion engine 10. The broken line in the figure is a map when the excess air ratio λ is 1, and the solid line in the figure is a map when the excess air ratio λ is 2. As shown in FIG. 3 (b), the torque of the internal combustion engine 10 increases as the rotational speed of the internal combustion engine 10 increases, but the internal combustion engine increases as the rotational speed of the internal combustion engine 10 increases with a predetermined rotational speed as a boundary. A torque of 10 decreases. The control unit 12 controls the flow rate control valve 9, the internal combustion engine 10, and the injector 11 based on the map of FIG.

  FIG. 4 is a schematic diagram showing an example when the fuel cell system 100 according to the present invention is applied to a hybrid vehicle. As shown in FIG. 4, the hybrid vehicle 200 includes a fuel cell system 100, a storage battery 21, a power generation device 22, a power transmission device 23, a plurality of wheels 24, and a regeneration device 25.

  The electric power generated in the fuel cell of the fuel cell system 100 is supplied to the power generation device 22 or stored in the storage battery 21 and then supplied to the power generation device 22. The power generation device 22 includes a converter, an inverter, an electric motor, and the like, converts electric power supplied from the fuel cell system 100 or the storage battery 21 into a shaft output, and transmits the shaft output to the power transmission device. The power transmission device 23 transmits the given shaft output to the wheels 24. As a result, the hybrid vehicle 200 starts operating.

  Subsequently, the hybrid vehicle 200 switches the power to the internal combustion engine as the load increases. First, the power transmission device 23 stops supplying the shaft output from the power generation device 22. Next, power generated by the internal combustion engine of the fuel cell system 100 is given to the power transmission device 23 as a shaft output. The power transmission device 23 transmits the given shaft output to the wheels 24. If the load further increases, the power transmission device 23 transmits the shaft output given from both the internal combustion engine of the fuel cell system 100 and the power generation device 22 to the wheels 24.

  The regeneration device 25 includes a generator and the like. When the user decelerates the hybrid vehicle 200, the generator of the regenerative device 25 converts the power of the wheels 24 into electric power and supplies the converted electric power to the battery 21.

  Thus, by applying the fuel cell system 100 according to the present invention to a hybrid vehicle, it is possible to select the power of either one or both of the electric motor and the internal combustion engine according to the driving situation. Thereby, thermal efficiency can be improved.

  Next, carbon deposition in the reforming part 3a in FIG. 1 will be described. FIG. 5 is a diagram for explaining carbon deposition. 5 indicates the S / C ratio in the reforming unit 3a, and the horizontal axis in FIG. 5 indicates the excess air ratio λ in the reforming unit 3a. Here, S / C ratio shows the molar ratio of the water vapor | steam supplied to the reforming part 3a, and the carbon in the gasoline supplied to the reforming part 3a.

  As shown in FIG. 5, when the S / C ratio is 1.5 or more, water vapor is excessively supplied to gasoline supplied to the reforming unit 3a, and carbon is not deposited. However, as the amount of reformed gas supplied to the internal combustion engine 10 increases, the amount of water vapor generated at the cathode 5b decreases. Thereby, the amount of water vapor supplied to the reforming unit 3a is reduced, and the S / C ratio is reduced. If the S / C ratio is 1.5 or less, the steam necessary for the steam reforming reaction is insufficient, and carbon can be deposited in the reforming section 3a.

  Next, the control performed by the control unit 12 to prevent carbon deposition in the reforming unit 3a when the internal combustion engine 10 is operated will be described. FIG. 6 is a flowchart illustrating the control performed by the control unit 12.

  As shown in FIG. 6, the control unit 12 determines whether or not it is necessary to supply hydrogen to the internal combustion engine 10 (step S1). Specifically, the determination is made based on whether the internal combustion engine 10 performs high load rotation or high speed rotation. If it is determined in step S1 that hydrogen needs to be supplied to the internal combustion engine 10, the control unit 12 fully opens the steam flow rate control valve 14 to supply steam to the reforming unit 3a (step S2). . Hereinafter, the control unit 12 repeats the operation from Step S1.

  In step S1, when it is determined that it is not necessary to supply hydrogen to the internal combustion engine 10, the control unit 12 controls the water vapor flow rate control valve 14 to be fully closed to stop the supply of water vapor to the reforming unit 3a. (Step S3). Hereinafter, the control part 12 repeats from the operation | movement of step S1.

  As described above, by supplying hydrogen to the internal combustion engine 10, even if the steam supplied from the cathode off gas to the reforming unit 3a is insufficient, the water vapor that has passed through the water vapor separation membrane 13 is supplied to the reforming unit 3a. Therefore, it is possible to prevent carbon from being deposited in the reforming part 3a.

  FIG. 6 is a diagram illustrating another example of a flowchart regarding the control performed by the control unit 12. As shown in FIG. 6, the control unit 12 determines whether or not it is necessary to supply hydrogen to the internal combustion engine 10 (step S11). Specifically, the determination is made based on whether the internal combustion engine 10 performs high load rotation or high speed rotation. If it is determined in step S11 that hydrogen needs to be supplied to the internal combustion engine 10, the control unit 12 calculates the amount of hydrogen supplied to the internal combustion engine 10 (step S12). In this case, the amount of hydrogen supplied to the internal combustion engine 10 is calculated so that the combustion heat of gasoline supplied to the internal combustion engine 10 is five times the combustion heat of hydrogen supplied to the internal combustion engine 10.

  Next, the control unit 12 calculates the amount of gasoline to be supplied to the reforming unit 3a based on the hydrogen amount and the hydrogen amount necessary for the operation of the fuel cell 5 (step S13). Next, the control unit 12 calculates the amount of water vapor supplied from the cathode 5b to the reforming unit 3a based on the amount of hydrogen consumed in the anode 5a (step S14).

  Next, the control unit 12 fully opens the water vapor flow rate control valve 14 to supply water vapor to the reforming unit 3a (step S15). Next, the control unit 12 controls the injector 2 based on the calculation result in step S13 (step S16).

  Next, the control unit 12 controls the flow rate control valve 9 and the injector 11 so that the ratio of hydrogen to gasoline added to the internal combustion engine 10 becomes a target value (step S17). In this case, the flow rate control valve 9 and the injector 11 are controlled so that the combustion heat of gasoline supplied to the internal combustion engine 10 is five times the combustion heat of hydrogen supplied to the internal combustion engine 10. Next, the control unit 12 controls the air-fuel ratio of the internal combustion engine 10 so that the excess air ratio λ becomes about 2 (step S18). Hereinafter, the control unit 12 repeats the operation from step S11.

  If it is determined in step S11 that hydrogen does not need to be supplied to the internal combustion engine 10, the controller 12 supplies the anode 5a and the cathode 5b with hydrogen and oxygen in amounts necessary for power generation by the fuel cell 5, respectively. Thus, the injector 2 and the air pump 8 are controlled (step S19). In this case, the control unit 12 controls the air pump 8 according to the map of FIG.

  Next, the control unit 12 controls the flow control valve 9 so as to stop hydrogenation to the internal combustion engine 10 (step S20). Next, the control unit 12 controls the air-fuel ratio of the internal combustion engine 10 according to the base map (step S21). Next, the control unit 12 controls the water vapor flow rate control valve 14 to be fully closed to stop the supply of water vapor to the reforming unit 3a (step S22). Hereinafter, the control unit 12 repeats the operation from step S11.

  As described above, since the air-fuel ratio in the internal combustion engine 10 is controlled according to the amount of hydrogen supplied to the internal combustion engine 10, combustion with high thermal efficiency can be realized. Moreover, even if the steam required for the steam reforming reaction is insufficient, the proportion of the oxygen supply amount increases, so that it is possible to prevent carbon from being deposited in the reforming section 3a. Further, by supplying hydrogen to the internal combustion engine 10, even if the steam supplied from the cathode off gas to the reforming unit 3a is insufficient, the water vapor that has passed through the steam separation membrane 13 is supplied to the reforming unit 3a. Precipitation of carbon in the mass portion 3a can be prevented.

  In the present embodiment, the reformer 3 corresponds to the reforming means, the steam separation membrane 13 corresponds to the steam separation means, the pipes 110, 111, 112 correspond to the bypass means, and the steam flow rate control valve 13 corresponds to the flow rate. Corresponding to the adjusting means, the pipe 105 corresponds to the off-gas supply means, the injector 2 corresponds to the fuel supply means, the air pump 8 corresponds to the oxygen supply means, the internal combustion engine 10 corresponds to the power unit, and the flow control valve 9 Corresponds to the reformed gas supply means, and the control unit 12 corresponds to the determination means and the control means.

  In this embodiment, the internal combustion engine 10 that can be used as a gasoline engine is used as a power unit. However, another internal combustion engine such as a hydrogen combustion turbine can be used, and an external combustion engine that uses hydrogen as fuel. Can also be used. Moreover, although the hydrogen separation membrane battery was used as the fuel cell 5, other fuel cells may be used. For example, a solid oxide fuel cell, a solid polymer fuel cell, or the like can be used. In this case, water vapor in the anode off gas can be used for the steam reforming reaction in the reforming unit 3a.

  Furthermore, although gasoline is used as the hydrocarbon fuel, other hydrocarbon fuels such as natural gas and methanol can also be used. In the present embodiment, the water vapor flow rate adjusting valve 14 is provided, but it is not always necessary to provide it. Further, the water vapor separation membrane 13 may be provided at a branch point between the pipe 102 and the pipe 110. In this case, it is possible to efficiently separate the steam that has not been used for the steam reforming reaction in the reforming unit 3a. Further, the reforming unit 3a of the present embodiment generates hydrogen gas by the steam reforming reaction, but may generate hydrogen in combination with other reforming reactions. Furthermore, in this embodiment, carbon deposition is prevented by introducing steam that has not been used in the steam reforming reaction in the reforming section 3a into the reforming section 3a, but other means for preventing carbon deposition You may combine.

  FIG. 8 is a schematic diagram showing the overall configuration of the fuel cell system 100a according to the second embodiment. The fuel cell system 100a differs from the fuel cell system 100 of FIG. 1 in that the steam flow rate control valve 14 is not provided, the piping 111 and the piping 105 are connected by the buffer 15, and the buffer 15 is the piping 112. Is connected to the reforming section 3a via

  The water vapor permeated by the water vapor separation membrane 13 flows through the pipe 111 and is stored in the buffer 15. The cathode off-gas flowing through the pipe 105 is supplied to the pipe 112 containing water vapor when passing through the buffer 15. Details of the buffer 15 will be described later.

  As described above, since the steam that has not been used for the steam reforming reaction in the reforming unit 3a is supplied again to the reforming unit 3a, the lack of steam in the reforming unit 3a is prevented. As a result, carbon deposition in the reforming part 3a is prevented.

  FIG. 9 is a schematic diagram for explaining the details of the buffer 15 of FIG. As shown in FIG. 9, the buffer 15 stores water. Pipes 105, 111, and 112 are connected to the buffer 15. The outlet of the pipe 105 is provided under the water surface of the buffer 15.

  The water vapor supplied from the pipe 111 is liquefied and stored in the buffer 15. The cathode off gas supplied from the pipe 105 is supplied to the pipe 112 through the water stored in the buffer 15. Thereby, the cathode off gas supplied to the pipe 112 contains a large amount of water vapor.

  In this embodiment, the pipes 110 and 111 correspond to bypass means.

1 is a schematic diagram showing an overall configuration of a fuel cell system according to the present invention. It is a schematic diagram explaining a mode that water vapor | steam is supplied to piping. It is a figure which shows the map which a control part follows when controlling the component apparatus of a fuel cell system. It is a schematic diagram which shows an example at the time of applying the fuel cell system which concerns on this invention to a hybrid vehicle. It is a figure for demonstrating carbon deposition. It is a figure which shows the flowchart in the case of supplying reformed gas to an internal combustion engine. It is a figure which shows the other example of the flowchart in the case of supplying reformed gas to an internal combustion engine. It is a schematic diagram which shows the whole structure of the fuel cell system which concerns on 2nd Example. It is a schematic diagram for demonstrating the detail of the buffer of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 2,11 Injector 3 Reformer 3a Reforming part 3b Combustion part 4,7 Heat exchanger 5 Fuel cell 5a Anode 5b Cathode 6,8 Air pump 9 Flow control valve 10 Internal combustion engine 12 Control part 13 Water vapor separation membrane 14 Steam flow control valve 15 Buffer 100 Fuel cell system

Claims (8)

A reforming means for reforming a hydrocarbon fuel by a steam reforming reaction to generate a reformed gas containing hydrogen;
Water vapor separation means for separating at least part of the water vapor in the reformed gas;
And a bypass means for introducing the water vapor separated by the water vapor separation means into the reforming means. Flow rate adjusting means for adjusting the flow rate of water vapor flowing through the bypass means;
2. The system according to claim 1, further comprising control means for controlling the flow rate adjusting means so as to adjust a flow rate of water vapor flowing through the bypass means. 3. The system according to claim 1, wherein a buffer for storing water vapor is provided in the bypass means. A fuel cell for generating electricity with hydrogen and oxygen;
The system according to any one of claims 1 to 3, further comprising an offgas supply means for supplying offgas containing moisture discharged from the fuel cell to the reforming means. A power unit driven by at least a part of the reformed gas and / or a hydrocarbon-based fuel;
A reformed gas supply means for supplying the reformed gas in an amount necessary for the operation of the power section to the power section;
Fuel supply means for supplying the hydrocarbon fuel to the reforming means,
The control means controls the fuel supply means so as to adjust the amount of the hydrocarbon-based fuel supplied to the reforming means in accordance with the amount of the reformed gas supplied to the power unit. Item 5. The system according to any one of Items 2 to 4. 6. The system according to claim 5, wherein the control means controls the flow rate adjusting means to be fully closed when the reformed gas is not supplied to the power unit. The system according to claim 5, wherein the power unit is an internal combustion engine. The system according to claim 1, wherein the water vapor separation means is an ion exchange resin that selectively permeates water vapor in the gas.

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