JP2015022852A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery in which the temperature of a fuel cell stack and a power generation auxiliary section can be raised efficiently during startup and power generation.SOLUTION: A fuel battery 10 includes a fuel cell stack 12 performing power generation by using liquid fuel and oxidant gas, a power generation auxiliary section 13 performing auxiliary processing for power generation, and an insulating container 14 for housing the fuel cell stack 12 and power generation auxiliary section 13. In the insulating container 14, two electric heaters 15, 16 are arranged to hold the fuel cell stack 12 in the vertical direction. A fuel cell controller 41 determines the operational state of the fuel battery 10 based on a stack temperature detected by a stack temperature detector 47, and controls an upper electric heater 15 and a lower electric heater 16 separately, so that the heater output is different during startup and power generation of the fuel battery 10.

Description

  The present invention relates to a fuel cell stack formed by stacking a plurality of flat plate fuel cells each having a fuel electrode, an air electrode, and an electrolyte layer, and a power generation auxiliary unit that performs auxiliary processing for power generation. It is related with a fuel cell provided with.

  Conventionally, a solid oxide fuel cell (SOFC) including a solid electrolyte layer (solid oxide) is known as a fuel cell which is a kind of power generation device. Solid oxide fuel cells have a very high energy conversion efficiency of 50% or more and can be miniaturized, and therefore are being developed as a power source for household cogeneration systems and automobiles.

  Specifically, the solid oxide fuel cell includes a fuel cell in which a fuel electrode in contact with the fuel gas and an air electrode in contact with the oxidant gas are disposed on both sides of the solid electrolyte layer. The fuel gas is for generating hydrogen, and the oxidant gas is for generating oxygen. Then, when hydrogen and oxygen react via a solid electrolyte layer (power generation reaction), DC power is generated with the air electrode as the positive electrode and the fuel electrode as the negative electrode.

  Generally, a solid oxide fuel cell is used in the form of a fuel cell stack formed by laminating a plurality of flat plate-shaped power generation cells. The solid oxide fuel cell is operated at a high temperature type of 1000 ° C. and an intermediate temperature type of 700 ° C. to 800 ° C. Therefore, it is necessary to store the fuel cell stack in a heat insulating container to keep the temperature. Moreover, since it is necessary to raise the temperature of the fuel cell stack to a temperature at which power can be generated when the fuel cell is activated, an electric heater, a combustor, and the like are accommodated in the heat insulating container (see Patent Documents 1 to 3).

  In the fuel cell of Patent Document 1, electric heaters are arranged at the upper and lower ends of the fuel cell stack, and the temperature of the fuel cell stack is raised by each heater, thereby shortening the startup time of the cell. Moreover, in the fuel cell of patent document 2, an electric heater is arrange | positioned inside a fuel cell stack, and a fuel cell is started rapidly by heating up a fuel cell stack with the electric heater. Furthermore, in the fuel cell of Patent Document 3, a combustor that generates heat by combustion of combustible gas is provided at an end portion in the stacking direction of the fuel cell stack, and the temperature of the fuel cell stack is increased by the combustor. With this configuration, the temperature distribution in the fuel cell stack is suppressed to be small, so that the power generation efficiency of the fuel cell is improved.

  Further, in the solid oxide fuel cell, a reformer or the like for causing a reforming reaction of the fuel gas to a composition suitable for power generation is accommodated in the heat insulating container. In general, the reforming reaction in the reformer is performed using a catalyst, but even in that case, a high temperature environment (for example, about 700 ° C.) is required to sufficiently advance the reaction. Accordingly, the reformer is configured to be heated using a combustor (such as a gas burner) or the like (see Patent Document 3).

JP-A-5-89900 JP 2007-103031 A JP 2009-93923 A

  However, in the fuel cell of Patent Document 3, since the temperature of the reformer and the fuel cell stack is raised using a combustor such as a gas burner, it is not possible to adjust the temperature so that the temperature distribution in the fuel cell stack is uniform. Have difficulty. Specifically, in the fuel cell of Patent Document 3, combustors are arranged on the upper side and the lower side of the fuel stack. The combustor (gas burner) can efficiently warm the member disposed on the upper side, but cannot warm the member disposed on the lower side. Therefore, it is difficult to improve the temperature distribution in the fuel cell stack even if the combustors are arranged above and below the fuel stack.

  Further, in the fuel cell of Patent Document 2, since the electric heater is disposed inside the fuel cell stack, the temperature difference between the stack center portion and the stack end portion increases, and the power generation efficiency decreases.

  On the other hand, in the fuel cell of Patent Document 1, since the electric heaters are arranged at the upper and lower ends of the fuel cell stack, the temperature difference in the fuel cell stack can be improved. However, when starting the fuel cell, it is necessary to raise the power generation auxiliary unit such as a reformer to a predetermined temperature. However, since the electric heaters of Patent Document 1 are arranged at the upper and lower ends of the fuel cell stack, The heater cannot efficiently raise the temperature of the power generation auxiliary unit.

  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 that can efficiently raise the temperature of the fuel cell stack and the power generation auxiliary unit at the time of start-up and power generation of the battery. is there.

  As means (means 1) for solving the above-mentioned problems, a plurality of flat plate fuel cells each having a fuel electrode, an air electrode and an electrolyte layer are laminated, and a fuel gas and an oxidant gas. A fuel cell stack that generates power using the power generation, a power generation auxiliary unit that performs auxiliary processing for power generation, and a heat insulating container that includes a heat insulating member and accommodates the fuel cell stack and the power generation auxiliary unit Two or more electric heaters provided in the heat insulation container and arranged to sandwich the fuel cell stack and the power generation auxiliary portion in the vertical direction, and temperature detection for detecting the temperature of the fuel cell stack And a fuel cell control means that is electrically connected to the electric heater and the temperature detection means and executes control necessary for starting, generating and stopping the fuel cell, the fuel cell control means comprising: The operation state of the fuel cell is determined based on the temperature detected by the temperature detecting means, and the heater cell is positioned below the fuel cell stack so that the heater output differs between when the fuel cell is started and when generating power. There is a fuel cell in which an electric heater and the electric heater located on the upper side of the fuel cell stack are separately controlled.

  Therefore, according to the invention described in the means 1, two or more electric heaters are arranged so as to sandwich the fuel cell stack and the power generation auxiliary portion in the vertical direction. Then, the fuel cell control means determines the operating state of the fuel cell based on the temperature detected by the temperature detection means, and controls each electric heater so that the heater output differs between when the fuel cell is started and when power is generated. . Specifically, when the fuel cell is started, each electric heater is driven to quickly warm up the power generation auxiliary unit. Further, during power generation, the output of each electric heater is controlled so as to keep the temperature distribution in the fuel cell stack uniform in consideration of heat absorption and heat generation in the power generation auxiliary section. As a result, it is possible to generate power efficiently without using wasted power when starting up the fuel cell or generating power.

  The power generation auxiliary unit includes a combustor that purifies exhaust gas discharged from the fuel cell stack after the fuel gas passes through the fuel cell stack in the fuel cell stack, and includes a fuel cell stack and an electric heater located below the fuel cell stack. A combustor may be disposed between them. In this case, heat is generated when the exhaust gas is burned in the combustor, and it can be efficiently warmed from the lower side of the fuel cell stack by the combustion heat in the combustor. In consideration of heating by the combustor, each electric heater is controlled by the fuel cell control means, so that the power generation efficiency of the fuel cell can be increased without using wasted power.

  When the combustor is disposed on the lower side of the fuel cell stack, the electric heater located on the lower side of the fuel cell stack is a heater that is a portion that can be heated more than the electric heater located on the upper side of the fuel cell stack. The area may be small. In this case, the electric heater located on the lower side of the fuel cell stack may have a smaller heater maximum output than the electric heater located on the upper side of the fuel cell stack. Even in this case, the lower side of the fuel cell stack can be sufficiently heated by the combustor and the electric heater.

  During power generation of the fuel cell, the fuel cell control means stops driving the electric heater located below the fuel cell stack, and in the cell stacking direction in the fuel cell stack based on the temperature detected by the temperature detection means. The electric heater located on the upper side of the fuel cell stack may be controlled so that the temperature distribution is uniform. During power generation of the fuel cell, the lower side of the fuel cell stack can be warmed by the combustor. For this reason, by stopping the driving of the lower electric heater and controlling the upper electric heater, the temperature distribution in the cell stacking direction in the fuel cell stack can be made uniform while suppressing the power consumption of the electric heater. The power generation efficiency of the fuel cell can be increased.

  The temperature detection means has a detection unit for detecting the temperatures of the upper, middle and lower positions in the stacking direction of the fuel cells in the fuel cell stack, and the fuel cell control means at the time of starting the fuel cell and at the time of power generation May control the electric heater located on the upper side of the fuel cell stack and the electric heater located on the lower side of the fuel cell stack so that the temperature at each position becomes equal. If it does in this way, the temperature distribution of the cell lamination direction in a fuel cell stack can be made uniform, and the electric power generation efficiency of a fuel cell can be improved.

  The fuel cell may further include a voltage detection unit that detects a cell stack voltage of the fuel cell stack, and a power output unit that is electrically connected to the fuel cell stack and converts and outputs the power of the fuel cell stack. Good. In this case, when the fuel cell control means determines that the fuel cell can generate power based on the temperature detected by the temperature detection means and the cell stack voltage detected by the voltage detection means, the power output means outputs power from the power output means. Let it begin. If it does in this way, the output of the voltage from a fuel cell can be performed at an appropriate timing.

  The power generation assisting unit disposed between the fuel cell stack and the electric heater located below the fuel cell stack may include a reformer that reforms the fuel gas in addition to the combustor. Further, the reformer of the devices constituting the power generation assisting unit may be disposed at a position closest to the electric heater located on the lower side of the fuel cell stack. In this way, the reformer can be quickly warmed by the lower electric heater, so that the fuel gas can be reformed quickly.

  In a fuel cell, as a power generation auxiliary unit disposed between a fuel cell stack and an electric heater located below the fuel cell stack, a vaporizer that vaporizes liquid fuel and a reformer that reforms the fuel gas vaporized by the vaporizer. And a quality device. If it does in this way, a carburetor and a reformer can be warmed quickly by the lower electric heater, the time taken from the start of the fuel cell to the time of power generation can be shortened, and the power generation efficiency can be increased.

  As a device constituting the power generation auxiliary unit, a carburetor, a combustor, and a reformer may be arranged in this order from the lower side. Here, the vaporizer and the reformer are portions that absorb heat, and the combustor is a portion that generates heat. In this way, in the power generation assisting portion, the temperature difference in the power generation assisting portion can be suppressed and the power generation efficiency can be increased by alternately arranging the heat absorbing portions and the heat generating portions.

  In addition, the power generation assisting unit may be disposed with a gap with respect to the electric heater. When the power generation auxiliary part is arranged in this way, the entire power generation auxiliary part can be warmed by the electric heater. Further, it is possible to prevent damage to the power generation auxiliary part due to local heating.

  The fuel cell stack may be stacked above the power generation auxiliary unit, and the fuel cell stack and the power generation auxiliary unit may have different projected areas when viewed from the stacking direction. For example, when the power generation auxiliary unit is disposed below the fuel cell stack with the projected area of the power generation auxiliary unit smaller than that of the fuel cell stack, the fuel cell in the fuel cell stack is heated by the combustor in the power generation auxiliary unit. It can warm up effectively. In addition, when the power generation auxiliary part is disposed below the fuel cell stack with the projected area of the power generation auxiliary part larger than that of the fuel cell stack, the entire fuel cell stack is uniformly heated by heating the combustor in the power generation auxiliary part. Can do.

  The combustor is configured using at least one of a gas burner and a combustion catalyst. In the present invention, the combustor includes a heater that burns exhaust gas using a gas burner in addition to a combustor that burns and purifies exhaust gas using a combustion catalyst. Here, when a combustor is comprised using a gas burner, you may use an electric heater as an ignition source of the gas burner. In this case, it is not necessary to prepare a separate ignition source for the gas burner, so that the cost of fuel cell components can be reduced.

  The vaporizer is a vaporizer that vaporizes and mixes liquid fuel and water necessary for reforming the fuel gas. In this case, water is supplied to the vaporizer before the liquid fuel is supplied. If it does in this way, in a vaporization mixer, fuel gas and water vapor | steam can be mixed reliably, avoiding the precipitation of carbon by the thermal decomposition of liquid fuel.

  The fuel cell control means estimates the temperature in the vaporization mixer based on the temperature detected by the temperature detection means, and determines that the temperature in the vaporization mixer has reached the vaporization temperature of the liquid fuel. Supply of fuel gas from the generator to the power generation auxiliary unit may be started. In this way, the fuel gas vaporized in the vaporization mixer can be supplied to the reformer of the power generation auxiliary unit at an appropriate timing without providing the temperature detection means in the vaporization mixer.

The schematic block diagram which shows the fuel cell in this Embodiment. The expanded sectional view which shows a fuel cell stack. The schematic block diagram which shows the fuel cell in another embodiment in which an upper electric heater and a lower electric heater have the same heater effective area. The schematic block diagram which shows the fuel cell in another embodiment arrange | positioned in the state which the electric power generation auxiliary | assistant part contacted directly to the electric heater. The schematic block diagram which shows the fuel cell in another embodiment provided with the electric power generation auxiliary | assistance part which the projection area when seen from the lamination direction is equal to a fuel cell stack. The schematic block diagram which shows the fuel cell in another embodiment provided with the electric power generation auxiliary | assistance part with a projected area larger than a fuel cell stack when it sees from a lamination direction. The schematic block diagram which shows the fuel cell in another embodiment by which the electric power generation assistance part was divided | segmented and arrange | positioned up and down of the fuel cell stack. The schematic block diagram which shows the fuel cell in another embodiment provided with the combustor which consists of a gas burner. The schematic block diagram which shows the fuel cell in another embodiment with which the vaporization mixer was provided between the fuel cell stack and the electric heater.

  The fuel cell 10 of the present embodiment is a solid oxide fuel cell (SOFC). As shown in FIG. 1, a fuel cell 10 includes a fuel cell stack 12 formed by laminating a plurality of flat plate fuel cell cells 11, a power generation auxiliary unit 13 that performs auxiliary processing for power generation, and a fuel cell. The heat insulation container 14 which accommodates the stack | stuck 12 and the electric power generation assistance part 13 and the two electric heaters 15 and 16 provided in the upper side and the lower side in the heat insulation container 14 are provided.

  As shown in FIG. 2, the fuel cell 11 constituting the fuel cell stack 12 includes an air electrode 21, a fuel electrode 22, and a solid electrolyte layer 23, and generates electric power through a power generation reaction. In the present embodiment, the number of stacked fuel cells 11 in the fuel cell stack 12 is about 20. In addition to the fuel cells 11, the fuel cell stack 12 is provided with a connector plate 24, a separator 25, an air electrode current collector 27, a fuel electrode current collector 28, and the like. Has been.

  More specifically, the connector plates 24 are made of a conductive material such as stainless steel, and a pair is arranged on both sides of the fuel cell 11 in the thickness direction. Each connector plate 24 ensures conduction between the fuel cells 11 in the thickness direction. The connector plate 24 disposed between the adjacent fuel cells 11 serves as an interconnector, and separates the adjacent fuel cells 11.

  The separator 25 is made of a conductive material such as stainless steel and has a substantially rectangular frame shape having a rectangular opening 29 at the center. The separator 25 functions as a partition plate between the fuel cells 11.

  The solid electrolyte layer 23 is formed in a rectangular plate shape by a ceramic material (oxide) such as yttria stabilized zirconia (YSZ). The solid electrolyte layer 23 is fixed to the lower surface of the separator 25 and is disposed so as to close the opening 29 of the separator 25. The solid electrolyte layer 23 functions as an oxygen ion conductive solid electrolyte body.

  An air electrode 21 in contact with the oxidant gas supplied to the fuel cell stack 12 is attached to the upper surface of the solid electrolyte layer 23, and the fuel supplied to the fuel cell stack 12 is also applied to the lower surface of the solid electrolyte layer 23. A fuel electrode 22 in contact with the gas is attached. That is, the air electrode 21 and the fuel electrode 22 are disposed on both sides of the solid electrolyte layer 23. The air electrode 21 is disposed in the opening 29 of the separator 25 so as not to contact the separator 25. In the fuel cell 11 of the present embodiment, the fuel chamber 31 is formed below the separator 25 and the air chamber 32 is formed above the separator 25.

In the fuel cell 11 of the present embodiment, the air electrode 21 is formed in a rectangular plate shape by LSCF (La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ ) which is a metal complex oxide. Has been. The fuel electrode 22 is formed in a rectangular plate shape by a mixture of nickel and yttria-stabilized zirconia (Ni-YSZ). In the fuel cell 11, the air electrode 21 functions as a cathode layer, and the fuel electrode 22 functions as an anode layer. The air electrode 21 is electrically connected to the connector plate 24 by the air electrode side current collector 27, and the fuel electrode 22 is electrically connected to the connector plate 24 by the fuel electrode side current collector 28. The air electrode side current collector 27 is made of a dense metal plate such as a SUS430 ferrite alloy. On the other hand, the fuel electrode side current collector 28 is made of, for example, a nickel porous body so that the fuel gas can pass therethrough.

  As shown in FIG. 1, the power generation auxiliary unit 13 of the present embodiment is configured to include a vaporization mixer 35, a reformer 36, and a combustor 37. The vaporizer 35 vaporizes and mixes liquid fuel (for example, light oil) and reformed water, and supplies the mixed fuel gas and water vapor to the reformer 36. As the liquid fuel, alcohol fuel such as methanol or ethanol may be used in addition to petroleum liquid fuel such as light oil.

  The reformer 36 reforms the fuel gas vaporized by the vaporizer 35 and water vapor to reform the fuel gas having a high hydrogen concentration, and supplies the fuel gas to the fuel cell stack 12. This fuel gas is supplied to the fuel chamber 31 of each fuel cell 11 in the fuel cell stack 12 and is used for the power generation reaction by contacting the fuel electrode 22.

  The combustor 37 has a combustion catalyst, and purifies the exhaust gas discharged from the fuel cell stack 12 (the fuel chamber 31 of each fuel cell 11) by using the catalyst for combustion. The exhaust gas purified by the combustor 37 is discharged to the outside of the heat insulating container 14 through the exhaust pipe 38.

  The fuel cell 10 is provided with a fuel cell control device 41 (combustion cell control means) for executing control necessary for starting, generating and stopping the battery 10. The fuel cell control device 41 is configured by a known computer including a CPU, ROM, RAM, input / output port, and the like. Further, the fuel cell 10 includes an air pump 42 that supplies an oxidant gas (specifically, air) to the fuel cell stack 12 (the air chamber 32 of each fuel cell 11), and a liquid fuel that is supplied to the vaporization mixer 35. A fuel pump 43 and a feed water pump 44 for supplying reforming water to the vaporizer 35 are provided. These pumps 42 to 44 are electrically connected to the fuel cell control device 41. Based on the control signal output from the control device 41, the pumps 42 to 44 are driven to control the supply timing and supply amount of air, liquid fuel and reformed water.

  In the fuel cell 10 according to the present embodiment, two electric heaters 15 and 16 are arranged in the heat insulating container 14 so as to sandwich the fuel cell stack 12 in the vertical direction. Further, between the lower electric heater 16 and the fuel cell stack 12, a reformer 36 and a combustor 37 among the devices constituting the power generation auxiliary unit 13 are disposed. The reformer 36 and the combustor 37 are provided integrally with the fuel cell stack 12. The fuel cell stack 12, the reformer 36, and the combustor 37 constitute a power generation module 39, and the power generation module 39 is sandwiched between the two electric heaters 15 and 16.

  Specifically, the reformer 36 in the power generation auxiliary unit 13 is disposed closest to the electric heater 16 located on the lower side of the fuel cell stack 12. The reformer 36 is disposed with a gap with respect to the electric heater 16, and a combustor 37 is provided above the reformer 36. Furthermore, the vaporizer 35 is disposed in a position where the lower electric heater 16 sandwiching the reformer 36 can be heated and close to the electric heater 16. In this way, the devices constituting the power generation assisting unit 13 are arranged with a gap from the electric heater 16.

  In the fuel cell 10 of the present embodiment, the fuel cell stack 12 is stacked and disposed above the power generation auxiliary unit 13 (the reformer 36 and the combustor 37), and the fuel cell stack 12 and the power generation auxiliary unit 13 include: The power generation auxiliary unit 13 is formed so that the projected area in the stacking direction is smaller than that of the fuel cell stack 12, that is, the area of the lower surface of the fuel cell stack 12 is the area of the upper surface of the reformer 36 and the combustor 37. Is bigger than.

  In the fuel cell 10, the electric heaters 15 and 16 in the heat insulating container 14 are connected to a heater power source 46, and the heater power source 46 is connected to a fuel cell control device 41. In the present embodiment, the electric heater 16 disposed on the lower side of the fuel cell stack 12 has a heater effective area which is a heatable portion is smaller than that of the upper electric heater 15 and the maximum heater output is higher than that of the upper electric heater 15. It is a small heater.

  The fuel cell stack 12 is provided with a stack temperature detector 47 (temperature detection means) made of a thermocouple or the like, and the vaporization mixer 35 is also provided with a vaporization temperature detector 48 made of a thermocouple or the like. In the present embodiment, the stack temperature detector 47 has a detector that detects the temperatures of the upper, middle, and lower positions P1, P2, and P3 in the stacking direction of the fuel cells 11 of the fuel cell stack 12. ing.

  Each temperature detector 47, 48 is connected to the fuel cell control device 41. Detection signals corresponding to the temperatures of the positions P1 to P3 of the fuel cell stack 12 and the temperature of the vaporization mixer 35 are input from the temperature detectors 47 and 48 to the fuel cell control device 41. The fuel cell control device 41 outputs a control signal to the heater power supply 46 based on the detection signal of the stack temperature detector 47, thereby causing the energization timing and supply power from the heater power supply 46 to the electric heaters 15 and 16 (heater power). Output). Further, the fuel cell control device 41 controls the supply timing of liquid fuel or reformed water to the vaporization mixer 35 (drive timing of the fuel pump 43 and the feed water pump 44) based on the detection signal of the vaporization temperature detector 48. To do.

  A voltage detector 52 (voltage detection means) for detecting a cell stack voltage is connected to the output terminal 51 of the fuel cell stack 12, and the cell stack voltage detected by the voltage detector 52 is supplied to the fuel cell control device 41. It comes to be taken in. Further, a fuel cell output converter 53 as power output means is connected to the output terminal 51 of the fuel cell stack 12, and the output converter 53 is connected to the fuel cell control device 41. The fuel cell output converter 53 operates based on a control signal from the fuel cell control device 41, converts the output voltage of the fuel cell stack 12 into a voltage of a predetermined standard, and then outputs the voltage to an external device. .

  Next, the operation of the fuel cell 10 of the present embodiment will be described.

  First, the fuel cell control device 41 outputs a control signal to the heater power supply 46 and starts energization of the electric heaters 15 and 16 from the heater power supply 46. Thereafter, the fuel cell control device 41 monitors the temperatures of the upper, middle, and lower positions P1 to P3 in the fuel cell stack 12 based on the detection signal from the stack temperature detector 47. The fuel cell control device 41 controls the power supplied from the heater power supply 46 to the electric heaters 15 and 16 based on the detection signal from the stack temperature detector 47. As a result, the electric heaters 15 and 16 raise the temperature of the power generation module 39 including the fuel cell stack 12 and the power generation auxiliary unit 13 uniformly.

  The fuel cell control device 41 determines the temperature of the vaporization mixer 35 based on the detection signal of the vaporization temperature detector 48. When the fuel cell control device 41 determines that the temperature of the vaporization mixer 35 has reached a temperature at which reformed water can be sufficiently vaporized (200 ° C. in the present embodiment), the fuel cell control device 41 drives the water supply pump 44 to vaporize. The reforming water is supplied to the mixer 35. Further, based on the detection signal of the vaporization temperature detector 48, the fuel cell control device 41 has reached the temperature at which the vaporizer 35 can sufficiently vaporize the liquid fuel (230 ° C. in the present embodiment). Is determined, the fuel pump 43 is driven to supply the liquid fuel to the vaporizer 35. At this time, in the vaporizer 35, the liquid fuel and the reformed water are vaporized and mixed. Then, the mixed fuel gas and water vapor are introduced into the reformer 36. In the reformer 36, the fuel gas and water vapor undergo a reforming reaction to obtain a fuel gas having a high hydrogen concentration. The fuel gas is introduced from the reformer 36 into the fuel cell stack 12, and the fuel gas is supplied to the fuel chamber 31 of each fuel cell 11 in the stack 12.

  Further, the fuel cell control device 41 drives the air pump 42 at a timing synchronized with the drive of the fuel pump 43. As a result, air is introduced from the air pump 42 into the fuel cell stack 12 and air is supplied to the air chambers 32 of the fuel cells 11. In the fuel battery cell 11, hydrogen and oxygen react (power generation reaction) through the solid electrolyte layer 23, thereby generating DC power with the air electrode 21 as the positive electrode and the fuel electrode 22 as the negative electrode.

  Exhaust gas containing fuel gas and oxidant gas that has not been used for power generation reaction in each fuel cell 11 is introduced into the combustor 37 through a gas discharge path (not shown) of the fuel cell stack 12. In the combustor 37, the exhaust gas is combusted and purified by the combustion catalyst, and then discharged to the outside of the heat insulating container 14 through the exhaust pipe 38.

  Thus, when combustion of exhaust gas is started in the combustor 37, the fuel cell stack 12 is heated by the combustion heat. At this time, in order to maintain the upper and lower heating balance, the fuel cell control device 41 outputs a control signal to the heater power supply 46 and stops energization from the heater power supply 46 to the lower electric heater 16. On the other hand, energization to the upper electric heater 15 is continued, and the temperature of the fuel cell stack 12 is raised by the upper electric heater 15 and the combustor 37. Further, the fuel cell control device 41 determines the temperatures of the upper, middle, and lower positions P1 to P3 in the fuel cell stack 12 based on the detection signal from the stack temperature detector 47, and the stacking direction in the fuel cell stack 12 is determined. The supply power (heater output) from the heater power supply 46 to the upper electric heater 15 is adjusted so as to maintain the temperature balance of the positions P1 to P3.

  Based on the detection signal from the stack temperature detector 47, the fuel cell control device 41 determines that the temperature of the fuel cell stack 12 (for example, the average temperature at each of the upper, middle, and lower positions P1 to P3) has reached 480 ° C. At times, the outputs of the air pump 42, the fuel pump 43 and the feed water pump 44 are increased. As a result, the amount of fuel gas and oxidant gas supplied to the fuel cell stack 12 is increased. At this time, since the amount of heat generated by the combustor 37 increases, the fuel cell control device 41 controls the heater power supply 46 according to the amount of heat generated, thereby generating electric power supplied from the heater power supply 46 to the upper electric heater 15. adjust. Specifically, the fuel cell control device 41 determines the heater output of the upper electric heater 15 so as to maintain the temperature balance of the positions P1 to P3 in the fuel cell stack 12 based on the detection signal of the stack temperature detector 47. Adjust. In this way, the temperature of the fuel cell stack 12 is raised to a temperature of 610 ° C. that is the power generation start temperature.

  At this time, the fuel cell control device 41 determines the cell stack voltage based on the detection signal of the voltage detector 52. When the fuel cell control device 41 determines that the fuel cell 10 can generate power based on the temperature of the fuel cell stack 12 and the cell stack voltage, the fuel cell output converter 53 is operated. As a result, the output voltage of the fuel cell stack 12 is converted into a voltage of a predetermined standard and then output from the fuel cell output converter 53 to an external device.

  During power generation of the fuel cell 10, the fuel cell control device 41 monitors the temperature of each position P 1 to P 3 of the fuel cell stack 12 based on the detection signal of the stack temperature detector 47. Then, the fuel cell control device 41 outputs a control signal to the heater power supply 46 in consideration of the amount of heat generated by the combustor 37 so that the temperature of each position P1 to P3 of the fuel cell stack 12 is kept uniform. The heater output of the heater 15 is controlled.

  Thereafter, when the fuel cell 10 is stopped, the fuel cell control device 41 stops driving the pumps 42 to 44 and then stops the energization of the electric heater 15 by the heater power supply 46. Thus, the power generation process of the fuel cell 10 is completed.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In the fuel cell 10 of the present embodiment, based on the stack temperature detected by the stack temperature detector 47, the fuel cell control device 41 causes the fuel cell 10 to operate (specifically, during startup or during power generation). ) Is determined. Then, the fuel cell control device 41 has an electric heater 16 positioned on the lower side of the fuel cell stack 12 and an upper position of the fuel cell stack 12 so that the heater output differs between when the fuel cell 10 is started and when generating power. The electric heater 15 is controlled separately. Specifically, when the fuel cell 10 is started, the upper electric heater 15 and the lower electric heater 16 are driven to quickly warm the power generation auxiliary unit 13. Further, during power generation, the outputs of the electric heaters 15 and 16 are controlled so as to keep the temperature distribution in the fuel cell stack 12 uniform in consideration of heat absorption and heat generation in the power generation auxiliary unit 13. As a result, it is possible to efficiently generate power without using wasted power when starting up the fuel cell 10 or generating power.

  (2) In the fuel cell 10 of the present embodiment, the power generation auxiliary unit 13 includes a combustor 37 that purifies the exhaust gas, and burns between the fuel cell stack 12 and the lower electric heater 16. A container 37 is arranged. In this case, heat is generated when the exhaust gas is burned in the combustor 37, and the fuel cell stack 12 can be efficiently warmed from below by the combustion heat in the combustor 37. When the exhaust gas is burned in the combustor 37, the fuel cell control device 41 stops the driving of the lower electric heater 16 and drives only the upper electric heater 15. The fuel cell stack 12 can be efficiently warmed by the upper electric heater 15 and the combustor 37. At this time, based on the stack temperature detected by the stack temperature detector 47, the upper electric heater 15 is controlled so that the temperature distribution in the cell stacking direction in each fuel cell stack 12 is uniform. If it does in this way, the power generation efficiency of fuel cell 10 can be raised, without using useless electric power.

  (3) In the fuel cell 10 of the present embodiment, the lower electric heater 16 is one that has a heater effective area and a heater maximum output that are heatable parts smaller than the upper electric heater 15. In the fuel cell 10, the fuel cell stack 12 can be heated by the combustor 37 disposed below the fuel cell stack 12. For this reason, even when a heater having a small heater effective area and a small heater maximum output is used as the lower electric heater 16, the fuel cell stack 12 and the power generation auxiliary unit 13 can be efficiently warmed.

  (4) In the fuel cell 10 of the present embodiment, the stack temperature detector 47 detects the temperatures of the upper, middle, and lower positions P1 to P3 in the stacking direction of the fuel cells 11 in the fuel cell stack 12. . And each electric heater 15 and 16 is controlled by the fuel cell control apparatus 41 so that the temperature of each position P1-P3 becomes equal. In this way, the temperature distribution in the cell stacking direction in the fuel cell stack 12 can be made uniform, and the power generation efficiency of the fuel cell 10 can be increased.

  (5) In the fuel cell 10 of the present embodiment, the fuel cell control device 41 generates power from the fuel cell 10 based on the stack temperature detected by the stack temperature detector 47 and the cell stack voltage detected by the voltage detector 52. It is determined whether or not it is possible. When the fuel cell control device 41 determines that the power generation is possible, the fuel cell output converter 53 starts outputting power. If comprised in this way, the output of the electric power from the fuel cell 10 to the external apparatus which is not shown in figure can be performed at an appropriate timing.

  (6) In the fuel cell 10 of the present embodiment, the power generation assisting portion 13 is arranged with a gap from the electric heater 16. When the power generation auxiliary unit 13 is arranged in this manner, the entire power generation auxiliary unit 13 can be efficiently warmed by the radiant heat of the electric heater 16. Further, it is possible to prevent the power generation auxiliary unit 13 from being damaged due to local heating.

  (7) In the fuel cell 10 of the present embodiment, the reformer 36 of the devices constituting the power generation assisting unit 13 is disposed closest to the electric heater 16 located on the lower side of the fuel cell stack 12. ing. In this way, the reformer 36 can be warmed quickly, so that the fuel gas can be reformed quickly.

  (8) In the fuel cell 10 of the present embodiment, the reforming water is supplied to the vaporization mixer 35 prior to the supply of the liquid fuel. If it does in this way, fuel gas and water vapor | steam can be reliably mixed in the vaporization mixer 35, avoiding the precipitation of carbon by thermal decomposition of liquid fuel.

  (10) In the fuel cell 10 of the present embodiment, the fuel cell stack 12 is stacked above the power generation auxiliary unit 13 (combustor 37). The fuel cell stack 12 and the reformer 36 and the combustor 37 of the power generation auxiliary unit 13 are formed such that the projection area in the stacking direction is smaller in the power generation auxiliary unit 13 than in the fuel cell stack 12. Further, the reformer 36 and the combustor 37 are integrally provided in the fuel cell stack 12. With this configuration, the temperature of the fuel cell 11 provided in the central portion of the fuel cell stack 12 can be reliably raised by the heat generated by the combustor 37.

  In addition, you may change embodiment of this invention as follows.

  In the fuel cell 10 of the above embodiment, the two electric heaters 15 and 16 are provided. However, if the electric heaters 15 and 16 are arranged so as to be sandwiched between the upper and lower sides of the fuel cell stack 12, Three or more electric heaters may be provided. Specifically, for example, two electric heaters may be arranged on the upper side of the fuel cell stack 12 and one electric heater may be arranged on the lower side.

  In the fuel cell 10 of the above embodiment, the upper electric heater 15 and the lower electric heater 16 use heaters having different heater effective areas and heater maximum outputs. However, the present invention is not limited to this. Like the fuel cell 10 </ b> A shown in FIG. 3, as the electric heater 16 </ b> A disposed on the lower side of the fuel cell stack 12, a heater having the same heater effective area and maximum heater output as the upper electric heater 15 may be used. In this case, it is possible to reduce costs by sharing parts.

  Further, when a heater having a sufficiently large heater effective area is used as the lower electric heater, the electric heater 16A and the power generation auxiliary unit 13 (reformer 36) are brought into direct contact as in the fuel cell 10B shown in FIG. May be. As described above, when the reformer 36 with endothermic heat is brought into direct contact with the electric heater 16A, the temperature of the reformer 36 can be quickly raised at the time of startup. For this reason, it is possible to advance the timing of supplying the fuel gas to the fuel cell stack 12 and to shorten the startup time.

  In the fuel cells 10, 10 </ b> A, and 10 </ b> B of the above-described embodiment, the power generation auxiliary unit 13 and the fuel cell stack 12 that is stacked above the power generation auxiliary unit 13 have a projected area in the stacking direction that is greater than that of the fuel cell stack 12. However, the present invention is not limited to this. For example, as in the fuel cell 10C shown in FIG. 5, the projected area when the fuel cell stack 12 and the power generation auxiliary unit 13A (the reformer 36A and the combustor 37A) are viewed from the stacking direction is substantially the same. You may form so that it may become. Further, as in the fuel cell 10D shown in FIG. 6, the size of the reformer 36B and the combustor 37B is increased, and the projected area in the stacking direction of the power generation auxiliary unit 13B and the fuel cell stack 12 is the fuel cell stack 12. You may form so that the electric power generation assistance part 13B may become larger than. If it does in this way, the inside of the heat insulation container 14 can be efficiently heated up with the heat_generation | fever of the combustor 37B in the power generation auxiliary | assistance part 13B.

  In the fuel cells 10, 10 </ b> A to 10 </ b> D of the above embodiment, the combustor 37 that constitutes the power generation auxiliary portions 13, 13 </ b> A, 13 </ b> B between the fuel cell stack 12 and the electric heaters 16, 16 </ b> A located below the fuel cell stack 12. , 37A, 37B and the reformers 36, 36A, 36B are disposed, but the present invention is not limited to this. As in the fuel cell 10E shown in FIG. 7, a combustor 37 is disposed between the fuel cell stack 12 and the electric heater 16 positioned below the fuel cell stack 12, and the electric heater 15 positioned above the fuel cell stack 12 is disposed. A reformer 36 may be disposed between the two. That is, the reformer 36 and the combustor 37 constituting the power generation assisting part 13 </ b> C are arranged separately on the upper side and the lower side of the fuel cell stack 12. Further, here, the vaporizer 35 is disposed at a position close to the upper electric heater 15 sandwiching the reformer 36. Thus, even when the fuel cell 10E is configured, the heat generating auxiliary portion 13C and the fuel cell stack 12 can be efficiently warmed using the upper electric heater 15 and the lower electric heater 16. In contrast to the fuel cell 10E, the reformer 36 may be disposed below the fuel cell stack 12 and the combustor 37 may be disposed above the fuel cell stack 12 to configure the fuel cell.

  In the fuel cells 10, 10A to 10E of the above embodiment, the combustors 37, 37A, and 37B include a combustion catalyst, but are not limited to this. Like the fuel cell 10 </ b> F shown in FIG. 8, a combustor 37 </ b> C (heater) configured using a gas burner instead of the combustion catalyst may be provided. The gas burner that constitutes the combustor 37 </ b> C shown in FIG. 8 is formed in an elongated shape in a pipe shape, and its starting end is connected to the upper surface of the fuel cell stack 12. Furthermore, the gas burner of the combustor 37 </ b> C passes near the upper electric heater 15 and is disposed along the vicinity of the side surface and the lower surface of the fuel cell stack 12. In the combustor 37C, the upper electric heater 15 is used as an ignition source of the gas burner, and the exhaust gas is burned. In this case, energization of the electric heater 15 may be stopped with the ignition of the gas burner of the combustor 37C. Furthermore, when the gas burner of the combustor 37 </ b> C misfires, the electric burner is used to reignite the gas burner. By doing so, the electric heater 15 can be commonly used as an ignition source for the combustor 37C (gas burner), so that the cost of components of the fuel cell 10F can be kept low. Further, the periphery of the fuel cell stack 12 can be efficiently warmed by the pipe-shaped gas burner.

  In the fuel cells 10, 10 </ b> A to 10 </ b> D of the above embodiment, the reformers 36 </ b> A constituting the power generation auxiliary portions 13, 13 </ b> A, 13 </ b> B between the fuel cell stack 12 and the electric heater 16 positioned below the fuel cell stack 12. Although 36B and the combustors 37, 37A, and 37B were provided, it is not limited to this. As in the fuel cell 10G shown in FIG. 9, in addition to the reformer 36 and the combustor 37 constituting the heat generation assisting portion 13D, the vaporization mixer 35A is provided between the fuel cell stack 12 and the lower electric heater 16. It may be arranged. In the fuel cell 10 </ b> G, the electric heater 16, the vaporizer / mixer 35 </ b> A, the combustor 37, the reformer 36, the fuel cell stack 12, and the electric heater 15 are arranged in this order from the lower side to the upper side in the heat insulating container 14. . During power generation by the fuel cell 10G, the fuel cell stack 12 and the combustor 37 are portions that generate heat, and the vaporization mixer 35A and the reformer 36 are portions that absorb heat. Therefore, when the fuel cell stack 12 and the combustor 37 are defined as heat generating portions, and the vaporizer 35A and the reformer 36 are defined as heat absorbing portions, the heat generating portions and the heat absorbing portions are alternately arranged in the heat insulating container 14. Is arranged. The fuel cell 10G is configured so that the heat distribution in the heat insulating container 14 is not biased to a predetermined location by arranging the devices in this way. In the fuel cell 10 </ b> G, the vaporizer / mixer 35 </ b> A constituting the power generation assisting unit 13 </ b> D is disposed with a gap from the combustor 37. In addition, when the heat distribution in the power generation auxiliary unit 13 is not biased, the vaporizer 35 </ b> A may be provided integrally with the reformer 36 and the combustor 37.

  In the fuel cell 10G shown in FIG. 9, the vaporizer 35A, the combustor 37, and the reformer 36 are arranged in this order from the lower side as devices constituting the power generation auxiliary unit 13, but these arrangements are appropriately arranged. It may be changed. For example, the vaporization mixer 35A, the reformer 36, and the combustor 37 may be arranged in this order from the lower side. The vaporizer 35 </ b> A and the reformer 36 are portions that serve as heat absorption units, but by arranging these devices in the vicinity of the electric heater 15, it is possible to quickly raise the temperature of each device when the battery is activated. For this reason, it is possible to vaporize the liquid fuel and reform the combustion gas in a relatively short time after starting the battery, and to shorten the start-up time of the fuel cell.

  In the above embodiment, the electric heaters 15, 16, and 16 </ b> A are manufactured as separate members from the heat insulating container 14, the upper electric heater 15 is fixed to the upper surface of the heat insulating container 14, and the lower electric heaters 16 and 16 </ b> A are Although it fixed to the lower surface of the heat insulation container 14, it is not limited to this. The electric heaters 15, 16, 16 </ b> A may be formed so that at least a part thereof is embedded in a heat insulating member constituting the heat insulating container 14. Specifically, in the heat insulating container 14, the upper electric heater 15 is embedded in the heat insulating member serving as the top plate, and the lower electric heaters 16 and 16A are embedded in the heat insulating member serving as the bottom plate. 16, 16A may be provided. That is, the fuel cell is configured in such a manner that the heat insulating material of the electric heaters 15, 16, 16 A is shared with the heat insulating member of the heat insulating container 14. If it does in this way, size reduction of a fuel cell can be achieved. In addition, the fuel cell manufacturing cost can be kept low by sharing parts.

  In the above embodiment, the stack temperature detector 47 that detects the temperature of the fuel cell stack 12 and the vaporization temperature detector 48 that detects the temperatures of the vaporization mixers 35 and 35A are provided. Is not to be done. An operation test or the like of the fuel cell 10 is performed in advance to obtain data indicating the correlation between the temperature change of the fuel cell stack 12 and the temperature change of the vaporizers 35 and 35A, and based on the temperature of the fuel cell stack 12 Thus, the temperature of the vaporizers 35 and 35A may be estimated. In this case, the vaporization temperature detector 48 can be omitted, and the component cost of the fuel cell 10 can be reduced.

  In the fuel cell 10 of the above-described embodiment, energization of the lower electric heaters 16 and 16A is stopped as the exhaust gas is burned in the combustor 37. However, the present invention is not limited to this. For example, when the calorific value of the combustor 37 is insufficient to heat the fuel cell stack 12, the lower electric heater 16 may be driven to warm the fuel cell stack 12. However, even in this case, the fuel cell stack 12 is efficiently heated by adjusting the heater output of the electric heater 16 in consideration of the combustion heat in the combustor 37.

  In the above embodiment, the fuel cell 10 that generates power using liquid fuel is embodied. However, the fuel cell 10 that uses gaseous fuel (fuel gas) may be embodied. In this case, the vaporizer 35 for vaporizing the liquid fuel may be omitted.

  In the above embodiment, the solid oxide fuel cell is embodied. However, other fuel cells such as a molten carbonate fuel cell (MCFC) may be embodied.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above are listed below.

  (1) In the means 1, a reformer for reforming the fuel gas as the power generation auxiliary unit disposed between the fuel cell stack and the electric heater located below the fuel cell stack, and the fuel cell stack And the combustor for purifying the exhaust gas discharged from the fuel cell stack after passing through the fuel cell stack in the fuel gas stack, wherein the reformer is located below the fuel cell stack. A fuel cell, wherein the fuel cell is disposed at a position closest to the heater.

  (2) In the means 1, as the power generation auxiliary portion disposed between the fuel cell stack and the electric heater located below the vaporizer, a vaporizer that vaporizes liquid fuel, and vaporized by the vaporizer A fuel cell comprising: a reformer that reforms fuel gas; and a combustor that purifies exhaust gas discharged from the fuel cell stack after the fuel gas passes through the fuel cell stack in the fuel cell stack. .

  (3) In the technical idea (2), the fuel cell is characterized in that the carburetor, the combustor, and the reformer are arranged in this order from the lower side as the devices that constitute the power generation auxiliary unit.

  (4) The fuel cell according to (1), wherein the power generation assisting portion is arranged with a gap with respect to the electric heater.

  (5) In the means 1, the fuel cell stack is stacked and disposed above the power generation assisting portion, and the projected area when viewed from the stacking direction is different between the fuel cell stack and the power generation assisting portion. The fuel cell characterized by the above-mentioned.

  (6) The fuel cell according to means 1, wherein the combustor is configured by using at least one of a gas burner and a combustion catalyst.

  (7) The fuel cell according to the technical idea (6), wherein the electric heater is used as an ignition source of the gas burner.

  (8) The fuel cell according to the first aspect, wherein the vaporizer is a vaporization mixer that vaporizes and mixes liquid fuel and water necessary for reforming the fuel gas.

  (9) The fuel cell according to the technical idea (8), wherein the water is supplied to the vaporizer before the liquid fuel is supplied.

  (10) In means 1, the fuel cell control means estimates the temperature in the vaporization mixer based on the temperature detected by the temperature detection means, and the temperature in the vaporization mixer is the vaporization of the liquid fuel. When it is determined that the temperature has been reached, supply of the fuel gas from the vaporizer to the power generation auxiliary unit is started.

  (11) The fuel cell according to means 1, wherein the electrolyte layer is a solid electrolyte layer made of a solid oxide.

DESCRIPTION OF SYMBOLS 10,10A-10G ... Fuel cell 11 ... Fuel cell 12 ... Fuel cell stack 13, 13A-13D ... Power generation auxiliary part 14 ... Thermal insulation container 15 ... Upper electric heater 16, 16A ... Lower electric heater 21 ... Air electrode DESCRIPTION OF SYMBOLS 22 ... Fuel electrode 23 ... Solid electrolyte layer 35, 35A as an electrolyte layer ... Evaporation mixer 36, 36A, 36B which comprises a power generation auxiliary part 37, 37A-37C ... Power generation auxiliary part which comprises a power generation auxiliary part Combustor 41 ... Fuel cell control device as fuel cell control means 47 ... Stack temperature detector as temperature detection means 52 ... Voltage detector as voltage detection means 53 ... Fuel cell output converter as power output means

Claims (7)

A fuel cell stack in which a plurality of flat plate-shaped fuel cells configured to include a fuel electrode, an air electrode, and an electrolyte layer are stacked, and power is generated using a fuel gas and an oxidant gas;
A power generation auxiliary unit that performs auxiliary processing for the power generation;
A heat insulating container configured using a heat insulating member and containing the fuel cell stack and the power generation auxiliary unit;
Two or more electric heaters provided in the heat insulating container and arranged so as to sandwich the fuel cell stack and the power generation auxiliary portion in the vertical direction;
Temperature detecting means for detecting the temperature of the fuel cell stack;
A fuel cell control means that is electrically connected to the electric heater and the temperature detection means, and executes control necessary for starting, generating and stopping the fuel cell;
The fuel cell control means determines an operating state of the fuel cell based on the temperature detected by the temperature detecting means, and the fuel cell stack is configured so that a heater output differs between when the fuel cell is started and when power is generated. A fuel cell, wherein the electric heater located on the lower side and the electric heater located on the upper side of the fuel cell stack are separately controlled.   The power generation auxiliary unit includes a combustor that purifies the exhaust gas discharged from the fuel cell stack after the fuel gas in the fuel cell stack passes through the fuel cell stack. The fuel cell according to claim 1, wherein the combustor is disposed between the electric heater located.   The heater according to claim 2, wherein the electric heater located on the lower side of the fuel cell stack has a smaller heater effective area that is a portion that can be heated than the electric heater located on the upper side of the fuel cell stack. Fuel cell.   4. The fuel cell according to claim 2, wherein the electric heater located on the lower side of the fuel cell stack has a smaller heater maximum output than the electric heater located on the upper side of the fuel cell stack.   During power generation of the fuel cell, the fuel cell control means stops driving the electric heater located below the fuel cell stack, and based on the temperature detected by the temperature detection means, the fuel The fuel according to any one of claims 1 to 4, wherein the electric heater located above the fuel cell stack is controlled so that a temperature distribution in a cell stacking direction in the battery stack is uniform. battery.   The temperature detection means has a detection unit that detects the temperature of each of the upper, middle, and lower positions in the stacking direction of the fuel cells in the fuel cell stack, and at the time of startup and power generation of the fuel cell, The fuel cell control means controls the electric heater located on the upper side of the fuel cell stack and the electric heater located on the lower side of the fuel cell stack so that the temperature at each position becomes equal. The fuel cell according to any one of claims 1 to 4. Voltage detecting means for detecting a cell stack voltage of the fuel cell stack;
A power output means that is electrically connected to the fuel cell stack and converts and outputs the power of the fuel cell stack;
When the fuel cell control means determines that the fuel cell can generate power based on the temperature detected by the temperature detection means and the cell stack voltage detected by the voltage detection means, the power output means The fuel cell according to claim 1, wherein output of the electric power is started.

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