JP2016046075A - Fuel cell power generation system, vehicle including fuel cell power generation system and starting method of fuel cell power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power generation system capable of reducing fuel consumption, required at the time of start-up, remarkably while avoiding damage on the metallic components in the fuel cell due to high temperature, when starting the fuel cell power generation system, and to provide a vehicle including this fuel cell power generation system, and a starting method of a fuel cell power generation system.SOLUTION: When starting a fuel cell power generation system 1, a combustion apparatus 11 for start-up generates combustion gas Gb1 to be supplied to a fuel cell 10, and a part of combustion gas Gb2 from the fuel cell 10 is returned to the combustion apparatus 11 for start-up from the downstream side of a fuel reformer 16. Based on the temperature T1 of the combustion gas Gb1 flowing into the fuel cell 10, or the temperature T2 of returning combustion gas Gb3, the fuel quantity and the amount of air supplied to the combustion apparatus 11 for start-up, and the flow rate of return gas Gb3 are controlled.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel cell power generation system capable of reducing a fuel consumption required for raising the temperature of a fuel cell to a temperature at which power generation is possible, a vehicle including the fuel cell power generation system, and a method for starting the fuel cell power generation system. About.

  In recent years, research and development of fuel cell vehicles (FCVs) that use electric energy generated by a chemical reaction between hydrogen and oxygen in a fuel cell to rotate the motor to obtain power for vehicle travel has been conducted in the automotive industry. It has been broken.

  In general, a fuel cell has an air electrode to which air is supplied, a fuel electrode to which hydrogen obtained by reforming the fuel with a fuel reformer or the like, and an ion sandwiched between the air electrode and the fuel electrode. A single cell is made up of an electrolyte that passes only the electrolyte and an external electronic circuit that connects the air electrode and the fuel electrode outside the electrolyte, and a plurality of the single cells are stacked (in a stacked state) via a separator. It is configured.

In a fuel cell power generation system using a fuel cell, hydrogen (H ₂ ) is decomposed by the action of a catalyst provided in the fuel electrode, and electrons generated by the decomposition are transferred to the air electrode via an external electronic circuit. To generate electricity. Hydrogen ions generated by the decomposition move to the air electrode through the electrolyte and return to the air electrode via an external electronic circuit, and also chemically react with oxygen in the air supplied to the air electrode. It becomes. Since this water is generated with heat generated by the above chemical reaction, it is high-temperature water vapor and is discharged from the fuel cell as part of the exhaust gas from the fuel cell.

  This fuel cell includes a polymer electrolyte fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC) depending on the fuel, electrolyte, and the like. ) And solid oxide fuel cells (SOFCs).

  This solid oxide fuel cell has a higher power generation temperature (about 700 ° C. to 800 ° C.) than other types of fuel cells, and in order to generate power by starting the fuel cell, It is necessary to raise the temperature of the fuel cell to at least about 700 ° C. at the rated power generation. In this temperature raising method, the combustion gas generated by the combustion of the fuel in the start-up combustion apparatus (burner or the like) is supplied to the fuel cell to transmit the heat of the combustion gas.

  For example, a fuel cell stack composed of a plurality of single cells provided with an air electrode, an electrolyte, and a fuel electrode, an oxidant gas supply means for supplying an oxidant gas to the air electrode, and a fuel gas supply means for supplying fuel gas A fuel cell system comprising a steam reforming means for reforming the fuel gas supplied to the fuel gas supply means by a steam reforming reaction, and is supplied to the startup fuel supply path in the startup combustor during startup The starting fuel is burned by the starting air supplied from the starting air supply path, and the temperature of the fuel cell stack is raised to a temperature suitable for power generation by this combustion temperature. However, after a steady state is reached after startup, the supply of startup fuel through the startup fuel supply path is stopped, the startup air supply through the startup air supply path is stopped, and the heat generated by the startup combustor A fuel cell system for stopping supply has been proposed (see, for example, Patent Document 1).

  However, since the amount of heat transfer by the combustion gas increases as the temperature difference increases, the temperature of the fuel cell is low at the start of temperature rise of the fuel cell, and the temperature difference from the combustion gas is large, so the amount of heat transfer increases and the temperature rises. Although the speed is high, as the temperature rises and the temperature of the fuel cell increases, the temperature difference from the combustion gas decreases, so the amount of heat transfer decreases and the temperature increase rate also decreases. Therefore, as the temperature of the fuel cell increases, the time required for the temperature increase increases, and the startup energy required to raise the temperature to a temperature at which power generation is possible, that is, the fuel between the start of startup of the fuel cell and the completion of startup. Consumption increases. For this reason, there is a problem that the time required for activation becomes longer and the amount of fuel consumption necessary for raising the temperature of the fuel cell to a temperature at which power can be generated increases.

JP 2009-76273 A (paragraph [0034])

  On the other hand, the present inventor has found that in a fuel cell power generation system using a solid oxide fuel cell, the combustion gas discharged from the fuel cell supplied with the starting combustion gas is about 800 ° C. Despite the high temperature, it is used to heat the fuel reformer downstream of the fuel cell, heat exchanger, and exhaust heat recovery in the hot water storage tank. In order to burn the fuel in excess of air so that most of the exhaust heat is released to the atmosphere without contributing and the temperature of the combustion gas in the start-up combustion device does not become too high, the fuel cell Considering that the combustion gas that is supplied and discharged from the fuel cell contains a large amount of oxygen, the exhaust gas has a large amount of exhaust heat and oxygen that is effectively used at start-up so that the temperature can be generated. Necessary when raising the temperature And it reached the finding that it is possible to reduce the fuel consumption.

  Further, in the recirculation of the combustion gas at the later stage of start-up, the temperature difference between the combustion gas and the fuel cell is small and the amount of heat transfer is reduced, so the temperature of the combustion gas discharged from the fuel cell is also increased. It has also been found that when the combustion gas is recirculated, the temperature of the combustion gas generated in the start-up combustion device rises and the metal parts in the fuel cell may be damaged.

  The present invention has been made in view of the above, and an object of the present invention is to occur in a start-up combustion device while avoiding damage due to high heat of metal parts in the fuel cell at the time of start-up of the fuel cell power generation system. By effectively using the amount of heat and oxygen contained in the combustion gas sent to the fuel cell, the fuel cell consumption can be significantly reduced when the temperature of the fuel cell is raised to a temperature at which power can be generated. An object of the present invention is to provide a power generation system, a vehicle including the fuel cell power generation system, and a method for starting the fuel cell power generation system.

  In order to achieve the above object, a fuel cell power generation system according to the present invention includes a fuel reformer that reforms fuel, and a fuel cell that generates power by receiving fuel and air reformed by the fuel reformer. The fuel is reformed by the fuel reformer, and then supplied to the fuel cell together with air to generate electric power. The exhaust gas from the fuel cell is sent to the fuel reformer, and the exhaust gas In a fuel cell power generation system for warming a fuel reformer, a start-up combustion device that generates combustion gas to be supplied to the fuel cell when the fuel cell power generation system is started, and a part of the combustion gas discharged from the fuel cell A recirculation passage that recirculates from the downstream side of the fuel reformer to the start-up combustion device, a flow rate adjustment valve that adjusts a flow rate of the combustion gas that flows through the recirculation passage, and a temperature of the combustion gas that flows into the fuel cell, or For start-up combustion equipment Combustion gas temperature for controlling the amount of fuel supplied to the start-up combustion device, the amount of air supplied to the start-up combustion device, and the flow rate of the combustion gas flowing through the return passage based on the temperature of the recirculation gas flowing And a control means.

  According to this configuration, a part of the combustion gas after passing through the fuel cell at the time of start-up is supplied as recirculation gas to the start-up combustion device together with air (fresh air), and the start-up by the combustion gas temperature control means Oxygen contained in the recirculated gas that flows back to the start-up combustion device while maintaining the combustion temperature in the combustion device at a constant temperature of, for example, about 900 ° C. to 1100 ° C. to prevent damage to metal parts and the like in the fuel cell Is effectively used as a high-temperature oxidant to promote combustion in the start-up combustion device, and high-temperature combustion gas can be supplied to the fuel cell with a small amount of fuel. As a result, it is possible to reduce the startup energy necessary for raising the temperature of the fuel cell to a temperature at which power can be generated, that is, the amount of fuel consumed between the start of startup of the fuel cell and the completion of startup.

  In particular, when a solid oxide form in which the temperature at which the fuel cell can generate electricity is as high as 700 ° C. to 800 ° C. is used as the fuel cell, the effect of reducing fuel consumption is particularly great. The more the system is activated, the greater the effect of reducing fuel consumption.

  In addition, since a part of the combustion gas after passing through the fuel cell is recirculated to the start-up combustion device via the recirculation passage from the downstream side of the fuel reformer, the fuel reformer is also installed together with the fuel cell. The fuel can be heated to a temperature at which it can be reformed. Therefore, when the temperature is raised to a temperature at which the fuel cell can generate power and the path is switched to the power generation path, the temperature of the fuel reformer has already been raised, so that power can be generated efficiently.

  Further, the combustion gas temperature control means controls the amount of fuel supplied to the startup combustion device based on the temperature of the combustion gas flowing into the fuel cell or the temperature of the recirculation gas returning to the startup combustion device, and the startup combustion device. Since the amount of air to be supplied and the flow rate of the combustion gas flowing in the recirculation passage can be controlled, the fuel cell can be efficiently saved while suppressing the rise in the temperature of the combustion gas generated in the start-up combustion device. Therefore, it is possible to avoid breakage due to high heat of metal parts or the like in the fuel cell at the time of starting the fuel cell power generation system.

  In the fuel cell power generation system, an air preheater for heating air supplied to the fuel cell using heat of exhaust gas generated in the fuel cell is provided on the downstream side of the fuel reformer, The reflux passage is configured to be branched from the downstream side of the air preheater.

  According to this configuration, a part of the combustion gas after passing through the fuel cell at the time of start-up is used as the recirculation gas, and the start-up is started from the downstream side of the air preheater provided on the downstream side of the fuel reformer via the recirculation passage. Since the air is recirculated to the combustion device, the air preheater is heated to reduce the temperature difference between the air supplied to the fuel cell and the exhaust gas discharged from the fuel cell during rated power generation after the fuel cell power generation system is started. It is possible to prevent breakage due to a temperature difference between components in the heat exchanger, particularly, ceramic components.

  In addition, a vehicle equipped with the fuel cell power generation system can achieve the same effects as the fuel cell power generation system.

  In addition, a method for starting a fuel cell power generation system according to the present invention for achieving the above object includes a fuel reformer and a fuel cell. The fuel is reformed by the fuel reformer, and then the fuel is combined with air. A method for starting a fuel cell power generation system that supplies power to a battery to generate power, sends exhaust gas from the fuel cell to the fuel reformer, and warms the fuel reformer with exhaust gas, the fuel cell power generation system At the start-up time, combustion gas supplied to the fuel cell is generated by the start-up combustion device, and a part of the combustion gas discharged from the fuel cell is sent from the downstream side to the start-up combustion device from the fuel reformer. Based on the temperature of the combustion gas flowing into the fuel cell or the temperature of the reflux gas returning to the start-up combustion device, the amount of fuel supplied to the start-up combustion device and the start-up combustion device are supplied Air When a method characterized by controlling the flow rate of the combustion gas reflux.

  According to this method, as in the fuel cell power generation system described above, the oxygen contained in the reflux gas recirculated to the start-up combustion device is effectively used as a high-temperature oxidant to promote combustion in the start-up combustion device. As a result, high-temperature combustion gas can be supplied to the fuel cell with a small amount of fuel, so that it is possible to reduce the amount of fuel consumed between the start of the start of the fuel cell and the completion of the start.

  In addition, since a part of the combustion gas after passing through the fuel cell is recirculated to the start-up combustion device from the downstream side of the fuel reformer, the temperature at which the fuel reformer can reform the fuel together with the fuel cell. When the temperature is raised to a temperature at which the fuel cell can generate electricity and switched to the power generation path, the temperature of the fuel reformer has already been raised, so that power can be generated efficiently.

  Furthermore, the combustion gas temperature control means relies on the temperature of the combustion gas flowing into the fuel cell or the temperature of the recirculation gas returning to the start-up combustion device, and the amount of fuel and air in the start-up combustion device being recirculated. By controlling the flow rate of the fuel cell, the fuel cell is heated while the fuel cell is efficiently saved while suppressing the rise in the temperature of the combustion gas generated in the start-up combustion device. In this case, it is possible to avoid damage due to high heat, such as metal parts in the fuel cell.

  According to the fuel cell power generation system, the vehicle equipped with the fuel cell power generation system, and the fuel cell power generation system startup method according to the present invention, at the time of startup of the fuel cell power generation system, damage to metal parts and the like in the fuel cell due to high heat is avoided. However, by effectively using the amount of heat and oxygen contained in the combustion gas that is generated by the start-up combustion device and sent to the fuel cell, the amount of fuel consumption required to raise the temperature of the fuel cell to a temperature at which power can be generated is reduced. It can be significantly reduced.

It is a figure which shows an example of a structure of the fuel cell power generation system of embodiment which concerns on this invention, and is a figure which shows the path | route at the time of starting. It is a figure which shows the other example of a structure of the fuel cell power generation system of embodiment which concerns on this invention, and is a figure which shows the path | route at the time of starting. It is a figure which shows an example of the relationship between the recirculation rate of the exhaust gas which concerns on this invention, and the reduction rate of fuel consumption. It is a figure which shows an example of a structure of the fuel cell power generation system of embodiment which concerns on a prior art, and is a figure which shows the path | route at the time of the rated power generation after starting. It is a figure which shows an example of a structure of the fuel cell power generation system of embodiment which concerns on a prior art, and is a figure which shows the path | route at the time of starting.

  DESCRIPTION OF EMBODIMENTS Hereinafter, a fuel cell power generation system according to an embodiment of the present invention, a vehicle including the fuel cell power generation system, and a startup method of the fuel cell power generation system will be described with reference to the drawings.

  First, in order to clarify the difference between the fuel cell power generation system according to the present invention and the fuel cell power generation system according to the prior art, a method for starting the fuel cell power generation system according to the prior art will be described.

  As shown in FIGS. 4 and 5, the fuel cell power generation system 1 </ b> X according to the prior art includes a fuel cell 10, a starting combustion device (burner or the like) 11, a blower 12, a fuel tank 13, a pressure regulating valve 14, and a combustor 15. , A fuel reformer 16, an air preheater (heat exchanger) 17, a hot water storage tank 18, a supply pump 19 and the like.

  The fuel cell 10 includes an air electrode (cathode) supplied with air (fresh air) A and a fuel electrode (anode) supplied with hydrogen H obtained by reforming the fuel F with the fuel reformer 16. A single cell having an electrolyte that allows only ions sandwiched between the air electrode and the fuel electrode to pass through, and an external electronic circuit that connects the air electrode and the fuel electrode outside the electrolyte. A plurality of layers are overlapped via a separator, that is, in a stacked state.

  At the time of power generation, as shown in FIG. 4, the air A from the blower 12 is heated by the air preheater 17 and then sent to the fuel cell 10, and the fuel F in the fuel tank 13 passes through the pressure adjustment valve 14. The fuel reformer 16 supplies the hydrogen H generated by the reforming of the fuel F to the fuel cell 10 to generate power, and the exhaust gas Ga1 from the fuel cell 10 is combusted. 15, the impurities contained in the exhaust gas Ga that are not consumed by the fuel cell 10 are combusted, and the exhaust gas Ga 2 thereafter is sent to the fuel reformer 16, the air preheater 17, and the hot water storage tank 18. The exhaust gas Ga2 warms the fuel reformer 16, the air preheater 17, and the hot water storage tank 18 to recover the exhaust heat.

In the rated power generation of the fuel cell 10, in each single cell of the fuel cell 10, oxygen in the air A supplied to the air electrode is decomposed into oxygen ions (O ^2-), the oxygen ions (O ^2-) Moves to the fuel electrode via the electrolyte. At the fuel electrode, oxygen ions (O ²⁻ ) electrochemically react with hydrogen to produce water. Electricity is generated by the electrons (2e ⁻ ) emitted at this time (H 2 + O ²⁻ → H ₂ O + 2e ⁻ ).

  The water generated at the time of power generation is high-temperature steam accompanied by heat generation due to the above chemical reaction, and is discharged from the fuel cell 10 as a part of the exhaust gas Ga1 from the fuel cell 10. The exhaust gas Ga1 includes, in addition to water vapor, air and hydrogen for unchemical reaction, fuel that has not been reformed by the fuel reformer 16, and the like. Combustion in the combustor 15 disposed downstream of the fuel reformer 16 and upstream of the fuel reformer 16 results in carbon dioxide, nitrogen dioxide, steam, or the like.

  Note that the temperature of the fuel reformer 16 is preferably maintained at an optimum temperature for reforming the fuel F into hydrogen H, for example, about 500 to 600 ° C., and the temperature of the air preheater 17 is 400. It is preferable to maintain at about ~ 500 ° C. When a solid oxide fuel cell is used as the fuel cell 10, city gas is usually mainly used as the fuel F.

  Then, as shown in FIG. 5, when the fuel cell power generation system 1 </ b> X is started, the start-up combustion apparatus 11 is supplied from the fuel tank 13 by the supply pump 19 via the pressure adjustment valve 14 by the air As from the blower 12. By burning the fuel Fs and supplying the combustion gas Gb1 to the fuel cell 10, the temperature of the fuel cell 10 is raised to a temperature at which power can be generated, for example, about 700 ° C to 800 ° C. And the combustion gas Gb2 discharged | emitted from the fuel cell 10 is sent to the fuel reformer 16, the air preheater 17, and the hot water storage tank 18, and these apparatuses 16-18 are warmed and the waste heat is collect | recovered. 4 and 5, the combustion gas Gb2 is bypassed the combustor 15, but may be configured to pass through the combustor 15. In this case, the combustion gas Gb2 is allowed to pass through without being burned in the combustor 15.

  As shown in FIGS. 1 and 2, the fuel cell power generation system 1 according to the present invention is based on the fuel cell power generation system 1 </ b> X according to the related art described above. In addition to the start-up combustion device 11 that generates the combustion gas Gb1 to be supplied, a part of the recirculation gas Gb3 of the combustion gas Gb2 discharged from the fuel cell 10 is sent from the downstream side of the fuel reformer 16 to the start-up combustion device 11. A reflux passage 21 for reflux is provided. In FIG. 1, the reflux passage 21 is branched from between the fuel reformer 16 and the air preheater 17, and in FIG. 2, the reflux passage 21 is branched from the downstream side of the air preheater 17.

  At the same time, the flow rate adjusting valve 22 for adjusting the flow rate of the recirculation gas Gb3 flowing through the recirculation passage 21 and the temperature T1 of the combustion gas Gb1 flowing into the fuel cell 10 or the temperature T2 of the recirculation gas Gb3 recirculating to the start-up combustion device 11 are obtained. Based on this, a combustion gas temperature control means for controlling the amount of fuel supplied to the start-up combustion device 11, the amount of air supplied to the start-up combustion device 11, and the flow rate of the recirculation gas Gb3 flowing through the recirculation passage 21 is provided. This combustion gas temperature control means is normally provided in a control device that controls the fuel cell power generation system 1.

  Further, a first temperature sensor 23 for measuring the temperature T1 of the combustion gas Gb1 flowing into the fuel cell 10 and a second temperature sensor 24 for measuring the temperature T2 of the recirculation gas Gb3 returning to the start-up combustion device 11. Or both.

  When starting the fuel cell power generation system 1, the combustion gas Gb 1 supplied to the fuel cell 10 is generated by the startup combustion device 11, and a part of the recirculation gas Gb 3 of the combustion gas Gb 2 discharged from the fuel cell 10 is fueled. Starting from the downstream side of the reformer 16 to the start-up combustion device 11, the start-up is based on the temperature T1 of the combustion gas Gb1 flowing into the fuel cell 10 or the temperature T2 of the recirculation gas Gb3 returning to the start-up combustion device 11. The temperature T1 of the combustion gas Gb1 flowing into the fuel cell 10 is controlled by controlling the amount of fuel supplied to the combustion device 11, the amount of air supplied to the start-up combustion device 11, and the flow rate of the recirculation gas Gb 3. Feedback control is performed so as to maintain a temperature in the range of 1 ° C. or higher and 1100 ° C. or lower, preferably a target temperature T1t of 1000 ° C.

  For example, first, even if the flow rate of the reflux gas Gb3 to be refluxed is refluxed, the maximum value is set in a range in which the fuel can be combusted by the startup combustion device 11. This flow rate is obtained in advance by experiments or numerical calculations. The next fuel amount and the air amount with respect to this fuel amount are set in advance, the temperature T1 of the combustion gas Gb1 is increased by increasing the fuel amount, and the temperature T1 of the combustion gas Gb1 is decreased by decreasing the fuel amount. Thus, feedback control is performed to increase or decrease the fuel amount and the air amount with respect to the temperature T1 of the combustion gas Gb1 so that the temperature T1 of the combustion gas Gb1 becomes the target temperature T1t.

  When feedback control is performed to increase or decrease the amount of fuel and the amount of air based on the temperature T2 of the recirculation gas Gb3, the relationship between the temperature T2 of the recirculation gas Gb3 and the temperature T1 of the combustion gas Gb1 is previously determined through experiments and numerical values. The target temperature T2t of the temperature T2 of the recirculation gas Gb3 is set by calculation or the like, and the fuel amount and the air with respect to the temperature T2 of the recirculation gas Gb3 are set so that the target temperature T2t becomes the temperature T2 of the recirculation gas Gb3. What is necessary is just to perform feedback control to increase or decrease the amount.

  As shown in FIG. 2, when the reflux passage 21 is branched from the downstream side of the air preheater 17 provided on the downstream side of the fuel reformer 16, the air preheater 17 is heated at startup. Therefore, during rated power generation after startup, the temperature difference between the air A supplied to the fuel cell 10 and the exhaust gas Ga2 discharged from the fuel cell 10 can be reduced. It is possible to prevent damage caused by temperature differences in ceramic parts.

  A part of the exhaust heat of the remaining combustion gas Gb4 (= Gb2-Gb3) that does not recirculate to the start-up combustion device 11 may be recovered by the hot water storage tank 18.

  In the fuel cell power generation system 1 according to the present invention, the path during rated power generation after startup and the operation method thereof are the same as those of the fuel cell power generation system 1X (see FIG. 4) according to the prior art. The vehicle according to the embodiment of the present invention is a vehicle equipped with the fuel cell power generation system according to the embodiment of the present invention.

  According to the fuel cell power generation system 1, the vehicle equipped with the fuel cell power generation system 1, and the method for starting the fuel cell power generation system, a part of the combustion gas Gb2 after passing through the fuel cell 10 is recirculated gas Gb3. As well as air (fresh air) As and is supplied to the start-up combustor 11 and the combustion gas temperature control means maintains the combustion temperature in the start-up combustor 11 at a constant temperature of about 900 ° C. to 1100 ° C., for example. Thus, the oxygen contained in the recirculation gas Gb3 recirculated to the start-up combustion device 11 is effectively used as a high-temperature oxidant while preventing damage to the metal parts and the like in the fuel cell 10. Combustion is promoted, and high-temperature combustion gas Gb1 can be supplied to the fuel cell with a small amount of fuel Fs. Thereby, it is possible to reduce the startup energy necessary for raising the temperature of the fuel cell 10 to a temperature at which power generation is possible, that is, the amount of fuel consumed between the start of startup of the fuel cell 10 and the completion of startup.

  Further, a part of the combustion gas Gb2 after passing through the fuel cell 10 is recirculated as a recirculation gas Gb3 from the downstream side of the fuel reformer 16 to the start-up combustion device 11 via the recirculation passage 21, so that the fuel cell 10 and the fuel reformer 16 can also be heated to a temperature at which the fuel F can be reformed. Therefore, when the temperature is raised to a temperature at which the fuel cell 10 can generate power and switched to the power generation path, the temperature of the fuel reformer 16 has already been raised, so that power can be generated efficiently.

  Further, the amount of fuel supplied to the startup combustion device 11 by the combustion gas temperature control means based on the temperature T1 of the combustion gas Gb1 flowing into the fuel cell 10 or the temperature T2 of the recirculation gas Gb3 returning to the startup combustion device 11 And the amount of air supplied to the start-up combustion device 11 and the flow rate of the recirculation gas Gb3 flowing through the recirculation passage 21 can be controlled, so that fuel can be efficiently saved and combustion generated in the start-up combustion device 11 Since the temperature of the fuel cell 10 can be increased while suppressing an increase in the temperature T1 of the gas Gb1, it is possible to avoid damage due to high heat of metal parts and the like in the fuel cell 10 when the fuel cell power generation system 1 is started.

  FIG. 3 shows a case where the recirculation rate C of the combustion gas indicating the ratio of the recirculation gas Gb3 to the combustion gas Gb2 at the time of start-up (= Gb3 / Gb2) and the recirculation rate C with respect to the fuel consumption when not recirculating. The result of having calculated | required the relationship of the reduction rate R of the fuel consumption of this is shown. The exhaust gas recirculation rate C is calculated based on the flow rate of the combustion gas Gb2 and the concentration of oxygen contained in the recirculation gas Gb3.

  According to FIG. 3, when the exhaust gas recirculation rate C is 10% to 80%, the fuel consumption reduction rate R is 5% to 30%. However, the exhaust gas recirculation rate C has an upper limit because it is necessary to prevent an excessive increase in the flow rates of the combustion gas Gb1 and the recirculation gas Gb3 and to prevent an excessive decrease in the oxygen concentration in the recirculation gas Gb3. The upper limit is about 70 to 90%.

  In FIG. 3, the exhaust gas recirculation rate C and the fuel consumption reduction rate R are linearly proportional, but this calculation does not take into account heat loss. The exhaust gas recirculation rate C and the fuel consumption reduction rate R are not necessarily linearly proportional as shown in FIG.

  According to the fuel cell power generation system 1, the vehicle equipped with the fuel cell power generation system 1, and the method for starting the fuel cell power generation system according to the present invention, when the fuel cell power generation system 1 is started, high heat such as metal parts in the fuel cell 10 is generated. When the fuel cell 10 is heated to a temperature capable of generating power by effectively using the amount of heat and oxygen of the combustion gas Gb1 generated in the start-up combustion device 11 and sent to the fuel cell 10 while avoiding damage due to The amount of fuel Fs required for the fuel consumption can be significantly reduced.

DESCRIPTION OF SYMBOLS 1, 1X Fuel cell power generation system 10 Fuel cell 11 Start-up combustion apparatus 12 Blower 13 Fuel tank 14 Pressure adjustment valve 15 Combustor 16 Fuel reformer 17 Air preheater 18 Hot water storage tank 19 Supply pump 21 Reflux passage 22 Flow rate adjustment valve 23 First temperature sensor 24 Second temperature sensor A, As air (fresh air)
F, Fs Fuel Gb1 Combustion gas Gb2 Combustion gas Gb3 from the fuel cell Recirculation gas Gb4 Remaining exhaust gas (Gb2-Gb3)
H Hydrogen

Claims (4)

A fuel reformer that reforms the fuel; and a fuel cell that generates electricity by receiving the fuel reformed by the fuel reformer and the air, and reforms the fuel by the fuel reformer. In the fuel cell power generation system for supplying power to the fuel cell together with air to generate power, sending exhaust gas from the fuel cell to the fuel reformer, and warming the fuel reformer with exhaust gas,
A start-up combustion device for generating combustion gas to be supplied to the fuel cell when the fuel cell power generation system is started;
A recirculation passage for recirculating a part of the combustion gas discharged from the fuel cell to the start-up combustion device from the downstream side of the fuel reformer;
A flow rate adjusting valve for adjusting the flow rate of the combustion gas flowing through the reflux passage;
Based on the temperature of the combustion gas flowing into the fuel cell or the temperature of the recirculation gas returning to the start-up combustion device, the amount of fuel supplied to the start-up combustion device, and the amount of air supplied to the start-up combustion device; A fuel cell power generation system comprising combustion gas temperature control means for controlling the flow rate of the combustion gas flowing through the reflux passage.   An air preheater that warms the air supplied to the fuel cell using heat of the exhaust gas generated in the fuel cell is provided on the downstream side of the fuel reformer, and the return passage is downstream of the air preheater. The fuel cell power generation system according to claim 1, wherein the fuel cell power generation system is provided by branching from the side.   A vehicle comprising the fuel cell power generation system according to claim 1.   A fuel reformer and a fuel cell are provided, fuel is reformed by the fuel reformer, and then supplied to the fuel cell together with air to generate power, and exhaust gas from the fuel cell is supplied to the fuel reformer. A starting method of a fuel cell power generation system for sending and warming the fuel reformer with exhaust gas, and at the time of starting the fuel cell power generation system, generating combustion gas to be supplied to the fuel cell with a starting combustion device; A part of the combustion gas discharged from the fuel cell is returned to the start-up combustion device from the downstream side of the fuel reformer, and is also returned to the start-up combustion device or the temperature of the combustion gas flowing into the fuel cell. A fuel cell that controls an amount of fuel supplied to the start-up combustion device, an amount of air supplied to the start-up combustion device, and a flow rate of the recirculating combustion gas based on a temperature of the recirculating gas Power generation system How to start.

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