JP2006107944A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system in which oxygen necessary for a reforming part is not insufficient. <P>SOLUTION: The fuel cell system is provided with: the fuel cell 5 on which, a cooling passage 5c in which an oxygen containing gas flows, is installed; a reformer 3 generating hydrogen-containing reformed gas from hydrocarbon based fuel by utilizing the oxygen containing gas; first passages (106, 5c, 110) connected to the reformer 3 through the cooling passage 5c; second passages (111, 112) connected to the reformer 3 without passing through the cooling passage 5c; an air pump 6 and a flow control valve 13 supplying the oxygen containing gas to either one or both of the first passages and the second passages; and a control part 12 controlling the oxygen containing gas supplying means so as to supply the oxygen containing gas to the second passages in the case that the quantity of the oxygen containing gas flowing in the first passages is less than that necessary for generating the reformed gas. <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.

  Since this steam reforming reaction is an endothermic reaction, it is necessary to apply heat to the reforming section. Therefore, a fuel cell system in which heat is applied to the reforming unit by a combustion device or the like has been developed. For example, a technique is disclosed in which air that has been heated to a high temperature by cooling a fuel cell is used to heat the reforming section through efficient combustion (see, for example, Patent Document 1). According to this technique, since it is not necessary to heat the combustion air, the fuel cell power generation system can be reduced in size.

On the other hand, a technique for providing a reformed gas generated by the reforming unit to a spark ignition engine is disclosed (for example, see 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.
JP-A-1-292757 JP 11-311136 A

  However, if the technique described in Patent Document 1 is applied to the technique described in Patent Document 2, when hydrogen is supplied to the spark ignition engine, the amount of power generated by the fuel cell decreases and the air required for cooling the fuel cell decreases. To do. Therefore, combustion air is insufficient and the amount of heat given to the reforming section is insufficient. As a result, the hydrogen produced by the steam reforming reaction is insufficient.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell system in which oxygen necessary for the reforming section is not insufficient.

  A fuel cell system according to the present invention includes a fuel cell provided with a cooling passage through which an oxygen-containing gas flows, and reforming means for generating a reformed gas containing hydrogen from a hydrocarbon fuel using the oxygen-containing gas. A first passage connected to the reforming means via the cooling passage, a second passage connected to the reforming means without going through the cooling passage, and the first passage and the second passage. An oxygen-containing gas supply means for supplying an oxygen-containing gas to one or both, and an oxygen-containing gas flowing in the first passage when the amount of oxygen-containing gas is less than that required for the generation of the reformed gas. Control means for controlling the oxygen-containing gas supply means so as to supply the oxygen-containing gas.

  In the fuel cell system according to the present invention, the oxygen-containing gas is supplied to one or both of the first passage and the second passage by the oxygen-containing gas supply means, and is supplied to the first passage. Is supplied to the reforming means through the cooling passage of the fuel cell, and the oxygen-containing gas supplied to the second passage is supplied to the reforming means without flowing through the cooling passage of the fuel cell. When the reformed gas containing hydrogen is generated from the hydrocarbon-based fuel using the oxygen-containing gas, and the amount of oxygen-containing gas flowing through the first passage is less than the amount necessary for generating the reformed gas, the second The oxygen-containing gas supply means is controlled by the control means so as to supply the oxygen-containing gas to the passage. Therefore, the oxygen-containing gas necessary for generating the reformed gas can be supplied to the reforming means. As a result, the reforming means can generate the necessary reformed gas.

  The oxygen-containing gas supply means includes a flow rate adjusting means for adjusting the flow rate of the oxygen-containing gas flowing through the second passage, and the control means requires the amount of oxygen-containing gas supplied to the second passage to generate the reformed gas. The flow rate adjusting means may be controlled so as to be the difference between the oxygen-containing gas amount and the oxygen-containing gas amount necessary for cooling the fuel cell. In this case, the oxygen-containing gas necessary for generating the reformed gas can be supplied to the reforming means without overcooling the fuel cell.

  The second passage may be a passage connecting the upstream side of the cooling passage of the first passage and the downstream side of the cooling passage of the first passage. In this case, the second passage is saved in space. Thereby, the fuel cell system according to the present invention can be reduced in size.

  The oxygen-containing gas may be air. In this case, a means for newly generating the oxygen-containing gas is not necessary. As a result, the fuel cell system according to the present invention can be reduced in size. Moreover, since the air which does not cost can be utilized, cost reduction can be achieved.

  The reforming means may include combustion means, and the combustion means may generate heat necessary for generating the reformed gas by a combustion reaction between the oxygen-containing gas and the combustible fuel. In this case, the heat of combustion of the oxygen-containing gas and the combustible fuel can be used for an endothermic reaction such as a steam reforming reaction.

  A power unit that is driven by at least a part of the reformed gas and / or a hydrocarbon-based fuel, and a reformed gas supply unit that supplies the reformed gas to the internal combustion engine are further provided, and the control unit is supplied to the power unit. The oxygen-containing gas supply means may be controlled so as to increase the amount of oxygen-containing gas supplied to the reforming means when the amount of the reformed gas increases.

  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 state of the fuel cell system according to the present invention is possible. Furthermore, even if the amount of the reformed gas supplied to the power unit increases, the oxygen-containing gas necessary for generating the reformed gas can be supplied to the reforming means. As a result, the reforming means can generate the necessary reformed gas.

  According to the present invention, the oxygen-containing gas necessary for generating the reformed gas can be supplied to the reforming means. As a result, the reforming means can generate the necessary reformed gas.

  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, and includes a control unit 12 and a flow control valve 13. 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.

  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.

  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 cooling passage 5 c of the fuel cell 5 through a pipe 106. The cooling passage 5c is connected to the combustion unit 3b via a pipe 110. A pipe 111 is branched from the middle of the pipe 106 and connected to the flow control valve 13. The flow control valve 13 is connected to the middle of the pipe 110 through the pipe 112.

  One end of the pipe 107 is connected to the upstream side of the heat exchanger 4 of the pipe 102, 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.

  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. Air that has not reacted with the water vapor and hydrogen ions generated at the cathode 5b is supplied to the reforming unit 3a through the pipe 105 as a cathode off gas, and is used for the steam reforming reaction.

  Thus, since the air that has not reacted with the hydrogen ions at the cathode 5b and the water vapor generated at the cathode 5b are used for the water vapor reforming reaction, it is not necessary to newly provide a water vapor supply means such as a water tank. 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 supplied to the pipe 106 is supplied to the cooling passage 5c and the pipe 111. The air supplied to the cooling passage 5 c cools the fuel cell 5 and is supplied to the pipe 110. Air supplied to the pipe 111 is supplied to the flow control valve 13. The flow control valve 13 supplies a necessary amount of air to the pipe 110 via the pipe 112 in accordance with an instruction from the control unit 12. The air supplied to the pipe 110 is supplied to the combustion unit 3b and used for combustion of hydrogen and carbon monoxide in the anode off gas.

  With this configuration, the amount of air supplied to the cooling passage 5c by the air pump 6 can be adjusted according to the amount of power generated by the fuel cell 5. Thereby, the temperature of the fuel cell 5 can be maintained within an appropriate range.

  In addition, even if the power generation amount of the fuel cell 5 decreases, if the hydrogen supply amount to the internal combustion engine 10 described later increases, the flow rate control valve 13 causes the fuel cell 5 to be not supercooled in the combustion section 3b. It is possible to supply air necessary for combustion. Thereby, a shortage of heat given to the reforming unit 3a can be prevented. As a result, necessary hydrogen can be generated from gasoline and necessary hydrogen can be supplied to the internal combustion engine 10.

  Furthermore, since air is used as a supply source of oxygen, a means for newly generating a gas containing oxygen is not necessary. As a result, the fuel cell system 100 according to the present invention can be reduced in size. Moreover, since the air which does not cost can be utilized, cost reduction can be achieved.

  Moreover, since the air supplied to the combustion part 3b via the piping 111 and 112 is supplied from the piping 106, it is not necessary to provide a means for supplying new air. Thereby, the fuel cell system 100 according to the present invention can be reduced in size.

  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 about 100 ° C. to 200 ° C., 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 map used when the control unit 12 controls the air pumps 6, 8, the flow control valve 9, the internal combustion engine 10, and the injector 11. FIG. 2A is a map showing the relationship between the power generation amount of the fuel cell 5 and the amount of oxygen necessary for the combustion unit 3b. The horizontal axis in FIG. 2 (a) indicates the amount of power generated by the fuel cell 5, and the vertical axis in FIG. 2 (a) indicates the amount of oxygen necessary for the combustion unit 3b. As shown in FIG. 2A, the amount of oxygen necessary for the combustion section 3b increases in proportion to the amount of power generated by the fuel cell 5.

  FIG. 2B is a map showing the relationship between the torque of the internal combustion engine 10 and the amount of oxygen necessary for the combustion unit 3b. The horizontal axis in FIG. 2 (b) indicates the torque of the internal combustion engine 10, and the vertical axis in FIG. 2 (b) indicates the amount of oxygen necessary for the combustion unit 3b. As shown in FIG. 2B, oxygen is not required in the combustion unit 3b up to a certain torque, but when a certain torque is reached, a predetermined amount of oxygen is required in the combustion unit 3b, and the torque exceeds that. The amount of oxygen required for the combustion part 3b increases in proportion. The control unit 12 calculates the amount of air that the air pump 6 supplies to the pipe 106 based on the maps of FIGS. 2 (a) and 2 (b).

  FIG. 2C is a map showing the relationship between the temperature of the fuel cell 5 and the amount of air necessary for cooling the fuel cell 5. The horizontal axis of FIG. 2 (c) indicates the temperature of the fuel cell 5, and the vertical axis of FIG. 2 (c) indicates the amount of air necessary for cooling the fuel cell 5. As shown in FIG. 2C, the amount of air required for cooling the fuel cell 5 increases in proportion to the square of the temperature of the fuel cell 5. The controller 12 calculates the amount of air supplied to the cooling passage 5c by the air pump 6 and the flow rate control valve 13 based on the map of FIG.

  FIG. 2D is a map showing the relationship between the amount of air supplied by the air pump 6 and the pump rotation speed of the air pump 6. The vertical axis in FIG. 2D indicates the pump rotation speed of the air pump 6, and the horizontal axis in FIG. 2D indicates the air supply amount by the air pump 6. As shown in FIG. 2D, the pump rotational speed of the air pump 6 increases in proportion to the square of the air supply amount of the air pump 6. The control unit 12 controls the air pump 6 based on the map of FIG.

  FIG. 2E 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. 2 (e) indicates the torque of the internal combustion engine 10, and the horizontal axis in FIG. 2 (e) 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. 2 (e), 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. 3 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. 3, 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. 4 is a diagram for explaining carbon deposition. 4 represents the S / C ratio in the reforming unit 3a, and the horizontal axis in FIG. 4 represents 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. 4, 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.

  In this case, the excess air ratio λ in the reforming unit 3a can be increased by increasing the amount of air supplied by the air pump 8. Thereby, carbon deposition in the reforming part 3a can be reliably prevented. For example, even when the S / C ratio becomes 0, the carbon excess in the reforming part 3a can be reliably prevented by setting the excess air ratio λ to 0.4 or more.

  Next, when the internal combustion engine 10 is operated, the control performed by the control unit 12 to supply air necessary for combustion in the combustion unit 3b will be described. FIG. 5 is a flowchart illustrating the control performed by the control unit 12.

  As shown in FIG. 5, the control unit 12 calculates the air amount A that needs to be supplied to the combustion unit 3b from the power generation amount of the fuel cell 5 and the hydrogen supply amount to the internal combustion engine 10 (step S1). In this case, the air amount A that needs to be supplied to the combustion unit 3b is calculated based on the graphs described in FIGS. 2 (a) and 2 (b).

  Next, the control unit 12 calculates the air amount B that needs to be supplied to the cooling passage 5c from the temperature of the fuel cell 5 (step S2). In this case, the air amount B that needs to be supplied to the cooling passage 5c is calculated based on the map described with reference to FIG.

  Next, the control unit 12 determines which of the air amount A required for the combustion unit 3b and the air amount B required for the cooling passage 5c is larger (step S3). When it is determined in step S3 that the amount of air A required for the combustion unit 3b is larger, the control unit 12 controls the air pump 6 so as to supply air necessary for the combustion unit 3b to the pipe 106. (Step S4). In this case, the air that needs to be supplied to the pipe 106 is calculated based on the map described in FIG.

  Next, the control unit 12 controls the flow control valve 13 so that the amount of air supplied to the pipe 111 is the difference between the amount of air A required for the combustion unit 3b and the amount of air B required for the cooling passage 5c ( Step S5). Hereinafter, the control part 12 repeats from the operation | movement of step S1.

  In step S3, when it is not determined that the air amount A required for the combustion unit 3b is larger, the control unit 12 controls the air pump 6 so as to supply air necessary for the cooling passage 5c to the pipe 106 ( Step S6). In this case, the air that needs to be supplied to the pipe 106 is calculated based on the map described in FIG.

  Next, the control unit 12 controls the flow control valve 13 so as to stop the air supply to the pipe 111 (step S7). Hereinafter, the control part 12 repeats from the operation | movement of step S1.

  As described above, even if the necessary air for the cooling passage 5c is reduced, the necessary air is supplied to the combustion unit 3b, so that it is possible to prevent a shortage of heat given to the reforming unit 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 calculates the amount of air to be supplied by the air pump 8 based on the amount of oxygen consumed in the cathode 5b and the amount of oxygen necessary for preventing carbon from being deposited in the reforming unit 3a (Step S12). S15). In this case, the amount of air necessary to prevent carbon from being deposited in the reforming unit 3a is calculated based on the graph described with reference to FIG.

  Next, the control unit 12 calculates the air amount A that needs to be supplied to the combustion unit 3b from the power generation amount of the fuel cell 5 and the hydrogen supply amount to the internal combustion engine 10 (step S16). In this case, the air amount A that needs to be supplied to the combustion unit 3b is calculated based on the maps described in FIGS. 2 (a) and 2 (b).

  Next, the control unit 12 calculates the air amount B that needs to be supplied to the cooling passage 5c from the temperature of the fuel cell 5 (step S17). In this case, the air amount B that needs to be supplied to the cooling passage 5c is calculated based on the map described with reference to FIG.

  Next, the control unit 12 determines which of the air amount A required for the combustion unit 3b and the air amount B required for the cooling passage 5c is larger (step S18). In step S18, when it is determined that the amount of air A required for the combustion unit 3b is larger, the control unit 12 controls the air pump 6 so as to supply air necessary for the combustion unit 3b to the pipe 106. (Step S19). In this case, the air that needs to be supplied to the pipe 106 is calculated based on the map described in FIG.

  Next, the control unit 12 controls the flow control valve 13 so that the amount of air supplied to the pipe 111 is the difference between the amount of air A required for the combustion unit 3b and the amount of air B required for the cooling passage 5c ( Step S20).

  Next, the control unit 12 controls the injector 2 based on the calculation result in step S13, and controls the air pump 8 based on the calculation result in step S15 (step S21). 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 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 S22). 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 is about 2 (step S23). Hereinafter, the control unit 12 repeats the operation from step S11.

  In step S18, when it is not determined that the air amount A required for the combustion unit 3b is larger, the control unit 12 controls the air pump 6 so as to supply air necessary for the cooling passage 5c to the pipe 106 ( Step S24). In this case, the air that needs to be supplied to the pipe 106 is calculated based on the map described in FIG.

  Next, the control part 12 controls the flow control valve 13 so that the air supply to the piping 111 is stopped (step S25). Hereinafter, the control unit 12 performs the operation of step S21.

  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 S26). 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 rate control valve 9 so as to stop the hydrogen addition to the internal combustion engine 10 (step S27). Next, the control unit 12 controls the air-fuel ratio of the internal combustion engine 10 according to the base map (step S28). Next, the control part 12 controls the flow control valve 13 so that the air supply to the piping 111 is stopped (step S29). 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. Furthermore, even if the air required for the cooling passage 5c decreases, the necessary air is supplied to the combustion unit 3b, so that it is possible to prevent a shortage of heat given to the reforming unit 3a. As a result, necessary hydrogen can be supplied to the internal combustion engine 10.

  In the present embodiment, the pipes 106 and 110 and the cooling passage 5c correspond to the first passage, the pipes 111 and 112 correspond to the second passage, and the air pump 6 and the flow control valve 13 serve as the oxygen-containing gas supply means. The flow rate control valve 13 corresponds to the flow rate adjusting means, the combustion part 3b corresponds to the combustion means, the reformer 3 corresponds to the reforming means, the internal combustion engine 10 corresponds to the power part, and the flow control valve 9 corresponds to the reformed gas supply means, and the control unit 12 corresponds to the control means.

  In the present embodiment, the pipe 111 is branched from the middle of the pipe 106, but may be connected to the outside of the fuel cell system 100 without passing through the pipe 106. Further, although the internal combustion engine 10 that can be used as a gasoline engine is used as a power unit, other internal combustion engines such as a hydrogen combustion turbine can be used, and an external combustion engine that uses hydrogen as fuel can also be used. Furthermore, 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 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. In addition, although gasoline is used as the hydrocarbon fuel, other hydrocarbon fuels such as natural gas and methanol may be used. Furthermore, in the present embodiment, the air supplied from the air pump is used for combustion in the combustion section 3b, but may be used for a partial oxidation reaction in the reforming section 3a.

1 is a schematic diagram showing an overall configuration of a fuel cell system according to the present invention. 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.

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 Flow control valve 100 Fuel cell system

Claims (6)

A fuel cell provided with a cooling passage through which oxygen-containing gas flows;
Reforming means for generating a reformed gas containing hydrogen from a hydrocarbon fuel using the oxygen-containing gas;
A first passage connected to the reforming means via the cooling passage;
A second passage connected to the reforming means without going through the cooling passage;
Oxygen-containing gas supply means for supplying the oxygen-containing gas to one or both of the first passage and the second passage;
The oxygen-containing gas supply means so as to supply the oxygen-containing gas to the second passage when the amount of the oxygen-containing gas flowing through the first passage is less than the amount necessary for generating the reformed gas. And a control means for controlling the fuel cell system. The oxygen-containing gas supply means includes a flow rate adjusting means for adjusting a flow rate of the oxygen-containing gas flowing in the second passage,
The control means is configured such that the amount of oxygen-containing gas supplied to the second passage is a difference between the amount of oxygen-containing gas necessary for generating the reformed gas and the amount of oxygen-containing gas necessary for cooling the fuel cell. 2. The fuel cell system according to claim 1, wherein the flow rate adjusting means is controlled. The second passage is a passage connecting an upstream side of the cooling passage of the first passage and a downstream side of the cooling passage of the first passage. The fuel cell system described. The fuel cell system according to claim 1, wherein the oxygen-containing gas is air. The reforming means includes combustion means,
The fuel cell according to any one of claims 1 to 4, wherein the combustion means generates heat necessary for generating the reformed gas by a combustion reaction between the oxygen-containing gas and a combustible fuel. system. 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 to the internal combustion engine;
The control means controls the oxygen-containing gas supply means so as to increase the amount of the oxygen-containing gas supplied to the reforming means when the amount of the reformed gas supplied to the power unit increases. A fuel cell system according to any one of claims 1 to 5, wherein

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