JP2010186668A - Heat storage device and fuel cell system using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase a heat storage volume for a cogeneration system using a fuel cell, while restraining enlargement of an installation space. <P>SOLUTION: The heat storage device 36 for storing exhaust heat recovered from the fuel cell includes a water storage tank 37 for storing the exhaust heat recovered by a heat exchanger 12 of an exhaust heat recovery unit in water, and heat storage tank 38 for storing the exhaust heat collected by the exhaust heat recovery unit in a latent heat storage material. The latent heat storage material has a larger heat storage capacity per unit volume by nearly one digit than sensible heat storage of water, so that the water storage tank 37 is downsized without changing a total heat storage volume of the heat storage device 36. Further, by using both the water storage tank 37 and the heat storage tank 38, the number of times of phase changes of the latent heat storage material is reduced to restrain its degradation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat storage device and a fuel cell system using the same.

  A polymer electrolyte fuel cell is formed by laminating a plurality of structures in which battery cells are sandwiched by separators, with the anode side electrode serving as the fuel electrode and the cathode side electrode serving as the oxidant electrode facing each other across the polymer electrolyte membrane. Configured. Since in-vehicle use places importance on mobility, there are usually many systems that use pure hydrogen as the fuel and air as the oxidant.

  However, for stationary and household use, a system that uses city gas or propane gas with a high methane component as the fuel is required because of infrastructure problems. In this case, in order to reform the fuel into hydrogen, a method using a fuel processor that generates hydrogen by mixing water vapor with the fuel is generally used. In any system, hydrogen supplied to the anode electrode side is ionized and flows in the solid polymer electrolyte membrane, reacts with oxygen on the cathode electrode side to generate water, and electric energy is obtained to the outside.

  By the way, this polymer electrolyte fuel cell generates exhaust heat of about 100 ° C. or less with generation of electric energy. For this reason, unless the battery efficiency reaches 100%, that is, unless the battery main body temperature can be generated at the ambient temperature, heat radiation from the high temperature battery to the surroundings is generated as heat. Also in a fuel processor for reforming fuel into hydrogen, since a combustor is usually used for heating a reforming reaction such as a reformer, combustion exhaust gas or exhaust heat from the outside of the fuel processor is generated.

  If such exhaust heat is used, hybrid operation with electric energy, that is, cogeneration operation is performed, so that it is possible to realize a very economical and energy-efficient operation that is friendly to the global environment. In recent years, development activities to introduce such a fuel cell system into the home have increased greatly, mainly in Japan, and practical application is coming soon. This is because, as a method of preventing global warming, this energy, which emits less carbon dioxide, has attracted attention, and attention has been focused on its energy saving and economic efficiency. It has been confirmed in demonstration tests at homes that increasing the amount of heat used is particularly effective as a system operation for improving energy efficiency and economy.

  On the other hand, the heat demand of each household is mainly dominated by cooking and hot water supply to the bath, and depends not only on the family structure but also on the installation area and environmental temperature. In general, the demand for heat is higher in winter than in summer and in cold regions than in warm regions, and the energy saving performance of the fuel cell system is enhanced. However, the power generation load and heat load at home do not necessarily coincide with each other in terms of time, and the former often peaks in the morning and evening, and the latter peaks after dinner. For this reason, a heat utilization system for temporarily storing the exhaust heat of the system is separately installed and stored as hot water in the hot water storage tank.

JP 2002-333207 A JP 2003-240465 A

  In order to increase the amount of waste heat stored in a cogeneration system using a fuel cell, a method of increasing the temperature of hot water or increasing the capacity of a hot water storage tank can be considered. There is a restriction that the limit temperature of hot water is determined by the system configuration. In addition, the hot water storage tank capacity is limited by the ease of installation and cost. Increasing the hot water storage tank capacity increases costs and requires a large installation space, which is not practical for general users.

  Further, for example, Patent Document 1 and Patent Document 2 disclose a method of using only a latent heat type heat storage tank for a heat utilization system. However, the user's convenience is not necessarily good only by this heat storage system.

  Accordingly, an object of the present invention is to increase the amount of heat storage while suppressing an increase in installation space in a cogeneration system using a fuel cell.

  In order to achieve the above-described object, the present invention provides a fuel cell system in which a fuel cell, an exhaust heat recovery device that recovers exhaust heat of the fuel cell, and waste heat recovered by the exhaust heat recovery device are stored in water. It has a hot water storage tank and a heat storage tank for storing the exhaust heat recovered by the exhaust heat recovery device in a latent heat storage material.

  The present invention also relates to a heat storage device for storing the exhaust heat recovered from the fuel cell, a hot water storage tank for storing the exhaust heat recovered by the exhaust heat recovery device in water, and the exhaust heat recovered by the exhaust heat recovery device. And a heat storage tank for storing the latent heat storage material.

  According to the present invention, in a cogeneration system using a fuel cell, it is possible to increase the amount of heat storage while suppressing an increase in installation space.

It is a block diagram which shows the detail of the thermal storage apparatus in 1st Embodiment of the fuel cell system which concerns on this invention. 1 is a block diagram of a first embodiment of a fuel cell system according to the present invention. It is a block diagram which shows the warm water flow at the time of the normal hot water storage of the thermal storage apparatus in 1st Embodiment of the fuel cell system which concerns on this invention. It is a block diagram which shows the warm water flow at the time of the thermal storage hot water operation of the thermal storage apparatus in 1st Embodiment of the fuel cell system which concerns on this invention. It is a block diagram which shows the warm water flow at the time of the thermal storage heat dissipation operation | movement of the thermal storage apparatus in 1st Embodiment of the fuel cell system which concerns on this invention. It is a block diagram which shows the detail of the thermal storage apparatus in 2nd Embodiment of the fuel cell system which concerns on this invention.

  Embodiments of a fuel cell system according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 2 is a block diagram of the first embodiment of the fuel cell system according to the present invention.

  The fuel cell system of the present embodiment has a fuel processing system, a battery main body 2, and a heat storage device 36. Most of the fuel processing system and the battery body 2 are accommodated in one package 16. The battery body 2 is also called CSA (Cell Stack Assembly).

  The fuel processing system, also called FPS (Fuel Processing System), includes a fuel supply source 3, a desulfurizer 4, a steam generator 5, a reformer 6, a CO shift reactor 7, a CO selective oxidizer 8, a steam separator 9, A quality water pump 11, two exhaust heat exchangers 81 and 82, and a tank 80 are provided. The reformer 6 is provided with a reforming combustor 10. The fuel supply source 3 is provided, for example, outside the package 16 and supplies a hydrocarbon-based fuel such as city gas or propane.

  The battery body 2 includes an anode electrode 13 and a cathode electrode 14. The anode 13 and the cathode 14 are provided with a solid polymer electrolyte membrane interposed therebetween. The battery body 2 is formed with a cooling flow path 70 for cooling the battery body 2.

  For example, when city gas is used as fuel, the fuel processing system performs reforming from city gas to hydrogen gas. The city gas is sent from the fuel supply source 3 to the reformer 6 by the blower 31 through the valve 20, the desulfurizer 4 and the valve 22. The sulfur gas is removed from the fuel such as city gas in the desulfurizer 4 by, for example, activated carbon or zeolite adsorption. Further, the water sent from the tank 80 through the filter 30 by the reforming water pump 11 is heated by the steam generator 5 and gasified. Only the water vapor is extracted from the gas sent from the water vapor generator 5 to the water vapor separator 9, passes through the valve 27, and merges with the desulfurized fuel gas. The liquid water separated by the water vapor separator 9 is sent to the tank 80 via the valve 83. The exhaust gas from the reformer 6 is sent to the steam generator 5 to heat the water, and then sent to the exhaust heat exchanger 81 provided in the tank 80, and then exhausted.

  The interior of the reformer 6 is heated by the reforming combustor 10 and the steam reforming reaction that is an endothermic reaction is maintained. The reforming combustor 10 is supplied with fuel from the fuel supply source 3 via a valve 21, and oxygen such as air is supplied by a blower 26 via a valve 25 or without this valve 25. Supplied. The reforming combustor 10 is supplied with gas discharged from the anode electrode 13 of the battery main body 2 containing hydrogen that has not been used for the battery reaction via the check valve 24.

In the reformer 6, hydrogen is generated from the reaction of city gas and water vapor by the catalyst, but CO is simultaneously generated. In a polymer electrolyte fuel cell, CO poisoning in a MEA (Membrane Electrode Assembly) composed of a solid polymer electrolyte membrane and a catalyst layer of the battery body 2 becomes a problem, and therefore, CO must be oxidized to CO ₂ . is there. For this reason, it is necessary to advance the shift reaction by H ₂ O in the CO shift reactor 7. Further, it is necessary to advance the oxidation reaction to such an extent that the catalyst is not poisoned by the CO in the CO selective oxidizer 8 by supplying the air from the CO selective oxidation air blower 18. The catalytic reaction temperatures including the reformer 6 are different from each other, and the temperature difference between the reformer gas upstream and downstream is large, from several hundred degrees of the reformer 6 to hundreds of degrees of the CO selective oxidizer 8. Therefore, a water heat exchanger for lowering the downstream temperature may be provided.

  Next, main process reactions in each catalyst are shown below. For example, in the case of city gas reforming mainly composed of methane components, the steam reforming reaction is represented by equation (1), the CO shift reaction is represented by equation (2), and the CO selective oxidation reaction is represented by equation (3).

CH ₄ + 2H ₂ O → CO ₂ + 4H ₂ (1)
CO + H ₂ O → CO ₂ + H ₂ (2)
2CO + O ₂ → 2CO ₂ (3)
The reformed gas that has passed through the CO selective oxidizer 8 mainly contains hydrogen, carbon dioxide gas, excess water vapor, and the like. These gases are sent to the anode electrode 13. The hydrogen gas sent to the anode electrode 13 passes through the electrolyte membrane through the MEA catalyst layer, and the proton gas H ⁺ is combined with oxygen and electrons in the air passing through the cathode electrode 14 by the cathode electrode air blower 15. Is generated. Accordingly, the anode electrode 13 is a negative electrode and the cathode electrode 14 is a positive electrode, and a DC voltage is generated with a potential. If an electrical load is connected between these potentials, the system has a function as a power source.

  The remaining outlet gas of the anode electrode 13 that is not used for power generation is used as a fuel gas for heating the steam heater 5 and the reformer 6. Further, the water vapor is recovered from the water vapor in the outlet of the cathode electrode 14 and the water vapor in the combustion exhaust gas by the exhaust heat exchanger 81, and water self-supporting in the system is achieved. On the other hand, the exhaust heat of the battery main body 2 is recovered by the exhaust heat exchanger 82 disposed in the circulation line of the battery cooling water pump 29 that passes through the cooling flow path 70. The hot water heated by exchanging heat in the exhaust heat exchangers 81 and 82 by the operation of the hot water circulation pump 33 is stored in the heat storage device 36 and used as hot water for hot water supply or a bath. Tap water is supplied to the heat storage device 36 through a water pipe 84 as necessary.

  FIG. 1 is a block diagram showing details of the heat storage device in the present embodiment. In FIG. 1, an exhaust heat exchanger 81 for exchanging heat with water vapor at the outlet of the cathode electrode 14 and water vapor in the combustion exhaust gas, and an exhaust heat exchanger 82 disposed in the circulation line of the battery cooling water pump 29. Are collectively shown as a heat exchanger 12. The heat exchanger 12, the battery cooling water pump, and the like form an exhaust heat recovery device that recovers exhaust heat from the fuel cell 2, the reformer 6, and the like.

  The heat storage device 36 includes a hot water storage tank 37 and a heat storage tank 38. The hot water storage tank 37 and the heat storage tank 38 are made of, for example, resin.

  The hot water storage tank 37 stores heated tap water. In the heat storage tank 38, two types of latent heat storage materials having different temperatures are divided into upper and lower parts and incorporated. The latent heat storage material is a material that stores not only sensible heat but also latent heat by phase change in the range of operating temperature. In the present embodiment, for example, paraffin-based triacontane (melting point 65 ° C.) or organic-based stearic acid (melting point 71 ° C.) is incorporated in the lower high-temperature side heat storage tank 60, and the upper low-temperature side heat storage tank 61 Contains paraffinic eicosane (melting point 36 ° C.) and trimyristin (melting point 33 ° C.). Inside the heat storage tank 38, two pipes 91 and 92 penetrate through the latent heat storage material.

  A pipe for circulating water is provided between the hot water storage tank 37 and the heat exchanger 12, and a first check valve 41, a first electric shut-off valve 43, and a hot water circulation pump are provided in the middle of the pipe. 33 is provided. A pipe 91 passing through the heat storage tank 38 is connected to the pipe via a second electric shut-off valve 44. The first check valve 41 is provided closer to the hot water storage tank 37 than the connecting portion. Further, the pipe 91 penetrating the heat storage tank 38 is connected to the second electric shut-off valve 44 via the second check valve 42 by a pipe extending from the opposite side of the heat storage tank 38 to the side connected via the second electric shut-off valve 44. It is connected between one electric shut-off valve 43 and the hot water circulation pump 33.

  A piping extends from the hot water storage tank 37 to, for example, a domestic water heater, and a fourth electric shut-off valve 47 and a hot water supply pressurizing pump 48 are provided in the middle of the piping. This pipe is connected to the heat storage tank via the third electric cutoff valve 46 upstream of the fourth electric cutoff valve 47 and via the third check valve 45 downstream of the fourth electric cutoff valve 47. 38 is connected to a pipe 92 penetrating through 38. The hot water supply pressurizing pump 48 is desirably disposed at the lower part in consideration of water filling and air venting.

  Thus, the hot water storage tank 37 and the heat storage tank 38 are provided in series, and the water stored in the hot water storage tank 37 and the latent heat storage material in the heat storage tank 38 are configured to be able to exchange heat.

  The heat storage tank 38 may be disposed below the hot water storage tank 37. The first check valve 41, the first electric cutoff valve 43, and the second electric cutoff valve 44 may be replaced with a three-way valve.

  The heat storage device 36 is operated in, for example, three operation modes of normal hot water storage, heat storage hot water, and heat storage and heat dissipation. The opening / closing of the valve and the driving of the pump in each operation mode are controlled by a control device, for example.

  FIG. 3 is a block diagram showing a hot water flow during normal hot water storage of the heat storage device in the present embodiment.

  During the normal hot water storage operation, the first electric cutoff valve 43 is opened and the second electric cutoff valve 44 is closed. During the normal hot water storage operation, the hot water circulation pump 33 is driven, and the exhaust heat of the fuel cell system 16 is recovered as hot water of 60 to 90 ° C. by the exhaust heat exchanger 12 and stored in the hot water storage tank 37 of the heat storage device 36. During hot water supply, when using hot water, the third electric shut-off valve 46 is closed, the fourth electric shut-off valve 47 is opened, the hot water supply pressurizing pump 48 is operated, and the hot water in the hot water storage tank 37 is used.

  FIG. 4 is a block diagram showing a hot water flow during the heat storage hot water storage operation of the heat storage device in the present embodiment.

  The heat storage hot water operation starts after the amount of heat stored in the hot water storage tank 37 reaches the maximum capacity, for example, after the temperature of the lower part of the hot water storage tank 37 rises and it is determined that the hot water storage is completed. In this case, the first electric cutoff valve 43 is closed and the second electric cutoff valve 44 is opened while the hot water circulation pump 33 is driven.

  In this state, the hot water passes through the hot water storage tank 37, passes through the heat storage heat exchanger 48 of the heat storage tank 38, and then returns to the hot water circulation pump 33. At this time, for example, a paraffin-based latent heat storage material undergoes a phase change from a solid state to a liquid state, and stores heat as sensible heat and latent heat. The two types of latent heat storage materials incorporated in the upstream high temperature side heat storage tank 60 and the downstream low temperature side heat storage tank 61 have different melting points, and the hot water passing through the downstream low temperature side heat storage tank 61 is the fuel cell 2 and The return temperature to the fuel processing system is controlled lower.

  When using hot water, the third electric shut-off valve 46 is closed, the fourth electric shut-off valve 47 is opened, and the hot water supply pressurizing pump 48 is operated. The hot water supply pressurizing pump 48 is arbitrarily variably controlled so as to satisfy the relationship between the required hot water supply amount and the hot water supply temperature in accordance with the pressure loss governed by the length and diameter of the hot water supply pipe of the house.

  FIG. 5 is a block diagram showing a hot water flow during the heat storage and heat radiation operation of the heat storage device in the present embodiment.

  During the heat storage and heat radiation operation, the hot water storage tank 37 is used for backup hot water. During the heat storage and heat radiation operation, the third electric cutoff valve 46 is opened, the fourth electric cutoff valve 47 is closed, and the hot water supply pressure pump 48 is operated. In this case, the water cooled after the hot water stored in the hot water storage tank 37 is used is heated in the low temperature side heat storage tank 61 and the high temperature side heat storage tank 60 of the heat storage tank 38, and cooked through the hot water supply pressure pump 48. Used for hot water in baths.

  A specific start determination at the time of the heat storage and heat radiation operation is, for example, a case where the temperature of the upper part of the hot water storage tank 37 is lowered and the use of the high temperature water in the hot water storage tank 37 is finished. At this time, for example, two types of paraffin-based latent heat storage materials having different melting points each dissipate heat to change the phase from a liquid state to a solid state. Thereby, the water sent from the hot water storage tank 37 can be heated and supplied by releasing sensible heat accompanying the temperature decrease of the latent heat storage material and releasing latent heat due to phase change. In the present embodiment, since trimyristin having a melting point of 33 ° C. is used as the latent heat storage material of the low temperature side heat storage tank 61, even if the water sent from the hot water storage tank 37 rises to about 30 ° C. in summer, the latent heat storage material It can receive heat from.

  The latent heat storage material has a heat storage capacity that is about one digit larger per unit volume than the sensible heat storage of water. For this reason, the hot water storage tank 37 can be reduced in size without changing the heat storage amount of the entire heat storage device 36, and even if the heat storage tank 38 is provided separately, the entire heat storage device 36 can be reduced in size. For example, if the hot water storage tank 37 has a capacity of 150 L (liters) and the heat storage tank 38 has a capacity of 20 L, a total of 170 L, the heat storage amount increases as compared with the case where the 200 L hot water storage tank 37 is used alone. Can be made compact. Moreover, compared with the case where heat is stored using only the latent heat storage material, the necessary amount of the latent heat storage material that is more expensive than water is limited, so that the cost can be reduced.

  Due to the compactness of the heat storage device 36, restrictions on the installation location are reduced. In addition, the heat storage device 36 can be easily transported along with the weight reduction.

  Furthermore, since the heat storage to the latent heat storage material is started after the heat storage to the water in the hot water storage tank 37 is completed, the average temperature of the water that exchanges heat with the latent heat storage material at the time of heat storage uses only the latent heat storage material. Higher than when storing heat. For this reason, the time which the heat storage to a heat storage material requires is shortened. In addition, when heat dissipation from the latent heat storage material is started after hot water cannot be supplied from the hot water storage tank 37, the average temperature of the water that exchanges heat with the latent heat storage material at the time of heat dissipation decreases. For this reason, the time until the heat radiation ends is shortened. Thus, the durability of the heat storage material can be greatly improved by shortening the time for heat storage and heat dissipation of the latent heat storage material.

  In the present embodiment, when heat is stored, heat is stored in preference to the hot water storage tank 37 and then stored in the heat storage tank 38. When heat is released, heat is preferentially released from the hot water storage tank 37 and then released from the heat storage tank 38. For this reason, the frequency | count of the phase change of the latent heat storage material inside the thermal storage tank 38 decreases, and deterioration of a latent heat storage material can be suppressed. Moreover, since the volume change accompanying the phase change of a latent heat storage material becomes small, deterioration of the thermal storage tank 38 etc. which store a latent heat storage material can also be suppressed.

  Further, the heat storage tank 38 using the latent heat storage material replaces the auxiliary combustion burner and the auxiliary electric heater that are conventionally provided to heat the hot water stored in the hot water storage tank 37, so that these devices are unnecessary. . For this reason, not only a significant cost reduction of the heat storage device 36 but also a cost reduction of the entire fuel cell system is facilitated, and introduction into a general household becomes easy. By using two types of high temperature side heat storage material and low temperature side heat storage material having different melting points as the latent heat storage material, the return temperature of the hot water to the fuel cell 2 can be controlled to be low, and the fuel cell system can be operated stably. .

  By making the hot water storage tank 37 and the heat storage tank 38 made of resin, the weight can be reduced and the cost can be reduced as compared with the case of using a metal. In particular, by using a latent heat storage material having a boiling point higher than that of water, hot water having a higher temperature can be supplied in a state where the heat storage medium does not boil, so the internal pressure of the hot water storage tank 37 is about 0.8 MPa. There is no need to increase it. The internal pressure of hot water storage tank 37 of the present embodiment can be set to about 0.17 MPa, for example. Further, when the latent heat storage material is stored in a metal container, the container may be corroded. However, in this embodiment, the latent heat storage material does not need to be held at a high pressure, so it is stored in a resin container. There is no problem.

  In this embodiment, two types of latent heat storage materials having different melting points are used, but one type or three or more types of latent heat storage materials may be used. Any latent heat storage material may be used as long as the melting point is higher than the temperature of the water supplied to the hot water storage tank 37 and lower than the maximum temperature of the exhaust heat recovery medium for recovering the exhaust heat of the fuel cell system. . The water supplied to the hot water storage tank 37 is generally tap water, and the temperature of the tap water does not exceed 30 ° C. even in summer. In addition, as the exhaust heat recovery medium for recovering the exhaust heat of the fuel cell system, water is normally used at normal pressure, so the maximum temperature of the exhaust heat recovery medium does not exceed approximately 95 ° C. Therefore, a material having a melting point of 30 ° C. or higher and 95 ° C. or lower may be used as the latent heat storage material.

  Further, for example, in a house having two or more floors, a hot water pipe laid inside the home becomes long and the pressure loss becomes large, and the supply flow rate of hot water supply may be insufficient. However, in the present embodiment, since the necessary supply amount can be secured by operating the hot water supply pressurizing pump 48, the convenience and comfort of hot water supply are improved.

[Second Embodiment]
FIG. 6 is a block diagram showing details of the heat storage device in the second embodiment of the fuel cell system according to the present invention.

  In the present embodiment, there is one pipe 93 through which water flows through the heat storage tank 38.

  A pipe for circulating water is provided between the hot water storage tank 37 and the heat exchanger 12, and a first check valve 41, a first electric shut-off valve 43, and a hot water circulation pump are provided in the middle of the pipe. 33 is provided. A pipe 93 that penetrates the heat storage tank 38 is connected to the pipe via a second electric shut-off valve 44. The first check valve 41 is provided closer to the hot water storage tank 37 than the connecting portion. Furthermore, the pipe 93 penetrating the heat storage tank 38 is connected via the fifth electric shut-off valve 50 by a pipe extending from the opposite side of the heat storage tank 38 to the side connected via the second electric shut-off valve 44. It is connected between one electric shut-off valve 43 and the hot water circulation pump 33. Further, the pipe 93 penetrating the heat storage tank 38 is upstream of the fourth electric shut-off valve 47 by a pipe extending from the opposite side of the heat storage tank 38 to the side connected via the second electric shut-off valve 44. It is connected via a third electric shut-off valve 46 to a pipe extending from the hot water storage tank 37 to a domestic water heater.

  A fourth electric shut-off valve 47 and a hot water supply pressurizing pump 48 are provided in the middle of the piping extending from the hot water storage tank 37 to a hot water heater in the home. This pipe is connected to a pipe 93 penetrating the heat storage tank 38 via a third check valve 45 and a sixth electric cutoff valve 51 on the downstream side of the fourth electric cutoff valve 47.

  The operation method is in accordance with the first embodiment. In the present embodiment, when using hot water in normal operation, the second electric shut-off valve 44, the third electric shut-off valve 46, the fifth electric shut-off valve 50, and the sixth shut-off valve 51 are closed, Open the fourth electric cutoff valve 43 and the fourth electric cutoff valve 47. In addition, when using hot water in the heat storage operation, the third electric cutoff valve 46, the sixth electric cutoff valve 51, and the first electric cutoff valve 43 are closed, and the second electric cutoff valve 44 and the fourth electric cutoff valve are closed. The valve 47 and the fifth electric shut-off valve 50 are opened. When using hot water for heat radiation operation, the second electric cutoff valve 44, the fourth electric cutoff valve 47, and the fifth electric cutoff valve 50 are closed, and the first electric cutoff valve 43 and the third electric cutoff valve 46 are closed. Then, the sixth electric shut-off valve 51 is opened.

  In this embodiment as well, the amount of stored heat can be increased while suppressing the expansion of the installation space, as in the first embodiment. Moreover, although the number of valves increases slightly, the internal structure of the heat storage tank 38 can be simplified as compared with the first embodiment. For this reason, when it is necessary to replace the latent heat storage material at intervals shorter than the lifetime of the entire fuel cell system, the structure of the replacement part can be simplified, and the labor and cost required for maintenance can be reduced.

[Other embodiments]
The above-described embodiments are merely examples, and the present invention is not limited to these. Moreover, it can also implement combining the characteristic of each embodiment.

DESCRIPTION OF SYMBOLS 2 ... Battery main body, 3 ... Fuel supply source, 4 ... Desulfurizer, 5 ... Steam generator, 6 ... Reformer, 7 ... CO shift reactor, 8 ... CO selective oxidizer, 9 ... Steam separator, 10 ... Reforming combustor, 11 ... reforming water pump, 12 ... heat exchanger, 13 ... anode electrode, 14 ... cathode electrode, 15 ... cathode air blower, 16 ... package, 18 ... CO selective oxidation air blower, DESCRIPTION OF SYMBOLS 20 ... Valve, 21 ... Valve, 22 ... Valve, 24 ... Check valve, 25 ... Valve, 26 ... Blower, 27 ... Valve, 29 ... Battery cooling water pump, 30 ... Filter, 31 ... Blower, 33 ... Hot water circulation pump 36 ... Thermal storage device, 37 ... Hot water storage tank, 38 ... Thermal storage tank, 41 ... First check valve, 42 ... Second check valve, 43 ... First electric shut-off valve, 44 ... Second electric shut-off Valve, 45 ... third check valve, 46 ... third electric cutoff valve, 47 ... fourth electric cutoff valve 48 ... Hot water supply pressure pump, 50 ... Fifth electric shut-off valve, 51 ... Sixth electric cut-off valve, 60 ... High temperature side heat storage tank, 61 ... Low temperature side heat storage tank, 70 ... Cooling flow path, 80 ... Tank, 81 ... exhaust heat exchanger, 82 ... exhaust heat exchanger, 83 ... valve, 84 ... water pipe, 91 ... piping, 92 ... piping, 93 ... piping

Claims (9)

A fuel cell;
An exhaust heat recovery device for recovering exhaust heat of the fuel cell;
A hot water storage tank for storing the exhaust heat recovered by the exhaust heat recovery device in water;
A heat storage tank for storing the exhaust heat recovered by the exhaust heat recovery device in a latent heat storage material; and
A fuel cell system comprising:   2. The fuel according to claim 1, wherein a melting point of the heat storage medium is higher than a temperature of water supplied to the hot water storage tank and lower than a temperature of an exhaust heat recovery medium for recovering exhaust heat of the fuel cell. Battery system.   3. The fuel cell system according to claim 1, wherein water stored in the hot water storage tank and the latent heat storage material are configured to be able to exchange heat. 4.   The heat storage tank includes a high temperature side heat storage tank storing a first latent heat storage material, and a low temperature side heat storage tank storing a second latent heat storage material having a melting point lower than that of the high temperature side heat storage tank. The fuel cell system according to any one of claims 1 to 3.   The fuel cell system according to any one of claims 1 to 4, wherein the heat storage tank is configured to store exhaust heat exceeding a heat storage capacity of the hot water storage tank.   6. The fuel cell system according to claim 1, wherein the latent heat storage material is configured to radiate heat from the hot water storage tank when the temperature is equal to or lower than a temperature at which heat can be radiated.   The fuel cell system according to any one of claims 1 to 6, wherein the hot water storage tank is a resin container.   The fuel cell system according to any one of claims 1 to 7, further comprising a variable capacity booster pump provided downstream of the hot water storage tank and the heat storage tank. In a heat storage device that stores exhaust heat recovered from a fuel cell,
A hot water storage tank for storing the exhaust heat recovered by the exhaust heat recovery device in water;
A heat storage tank for storing the exhaust heat recovered by the exhaust heat recovery device in a latent heat storage material; and
A heat storage device characterized by comprising:

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