JP3578148B2 - Fuel cell system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cell system, and more particularly to a fuel cell system having improved startup characteristics at low temperatures.
[0002]
[Prior art]
2. Description of the Related Art There is known a fuel cell that supplies hydrogen to a fuel electrode as fuel gas and oxygen-containing air to an air electrode to electrochemically react hydrogen and oxygen to generate power.
[0003]
The fuel cell requires a pure water supply system for humidifying the reaction gas with pure water, and a cooling system for cooling the fuel cell. These may freeze when the fuel cell is used below freezing, so it is necessary to release the freeze when starting the fuel cell, and it is important to efficiently perform this in order to enhance the startup characteristics. .
[0004]
Japanese Patent Application Laid-Open Nos. 9-147892 and 2000-164233 have proposed freezing cancellation at the time of starting a fuel cell system.
[0005]
[Problems to be solved by the invention]
However, the problem that the freezing can not be efficiently released and the time required for the start-up time is long has not been solved yet.
[0006]
The present invention has been proposed to solve such a problem, and provides a fuel cell system capable of completing warm-up in a short time by effectively utilizing heat energy of combustion gas at the time of startup. The purpose is to:
[0007]
[Means for Solving the Problems]
A first invention provides a fuel cell system that generates an electrochemical reaction between a fuel gas containing hydrogen and an oxidizing gas containing oxygen by using a fuel cell body having a fuel electrode and an air electrode, a fuel electrode and an air electrode. Means for supplying pure water for humidification to the oxidizing gas and the fuel gas to be supplied to the fuel cell, a cooling system for cooling the fuel cell body with cooling water, and a part of the fuel gas and A heat exchanger for heating the cooling water by the combustion gas obtained by burning the gas, a tank for storing the pure water for humidification, and a combustion gas discharged from the heat exchanger and stored in the storage tank. Heat exchange means for exchanging heat with pure water.
[0008]
According to a second aspect, in the first aspect, a combustor for burning a part of the fuel gas discharged from the fuel cell body and the oxidizing gas is provided upstream of the heat exchanger. The pure water storage tank is arranged so that heat can be transferred in proximity to the heat exchanger.
[0009]
In a third aspect based on the second aspect, fuel exhaust gas from the fuel electrode of the fuel cell main body is introduced into the combustor via a purge valve when the system is at low temperature.
[0010]
In a fourth aspect based on the first to third aspects, the heat exchange means is configured such that the combustion gas passes through the inside of the storage tank and applies heat to pure water.
[0011]
In a fifth aspect based on the first to third aspects, the heat exchange means is provided with a heat exchange portion adjacent to a bottom surface of the storage tank so that the combustion gas passes through the heat exchange portion. It is constituted by.
[0012]
In a sixth aspect based on the fourth or fifth aspect, a plurality of heat transfer plates for transferring heat from the combustion gas to pure water are arranged in the storage tank.
[0013]
In a seventh aspect based on the fourth or fifth aspect, the combustion gas from the combustor is directly introduced into the storage tank via a shutoff valve.
[0014]
In an eighth aspect based on the second to seventh aspects, a tank for supplying the pure water for humidification is provided above the storage tank, and is provided in a pipe connecting the tank and the storage tank. Is provided with a shut-off valve, an exhaust throttle valve is provided to throttle the combustion gas before discharging to the outside, and when the system is stopped, the shut-off valve is opened to recover pure water from the upper tank to the storage tank, At the time of startup, the exhaust throttle valve is throttled and the shut-off valve is opened to push the pure water to the upper tank by the exhaust pressure to be transferred.
[0015]
In a ninth aspect based on the eighth aspect, the pure water supply tank is arranged near at least one of the combustor, the heat exchanger, and the cooling system to exchange heat. ing.
[0016]
In a tenth aspect based on the second or third aspect, the cooling water of the cooling system is allowed to flow into the circulation pump via the combustor and the heat exchanger after passing through the fuel cell main body, or a radiator is provided. A switching valve is provided to switch whether the cooling water flows into the circulation pump via the circulating pump. When the temperature of the system is low, the cooling water is circulated through the combustor and the heat exchanger.
[0017]
In an eleventh aspect based on the tenth aspect, the cooling water discharged from the circulation pump is caused to flow to the pure water supply means before flowing into the fuel cell main body.
[0018]
In a twelfth aspect based on the sixth aspect, the storage tank attenuates and reduces pressure pulsation as a combustion gas silencer.
[0019]
In a thirteenth aspect based on the fifth aspect, the pressure of the combustion gas flowing through the heat exchange section is connected to the storage tank so as to be transmitted via a pipe, and the storage tank functions as a Helmholtz type muffler. .
[0020]
[Action / Effect]
In the first invention, the cooling water of the cooling system of the fuel cell is heated by the heat exchanger when the temperature of the system is low, and the temperature of the entire system is increased, while the combustion gas discharged from the heat exchanger and the pure water of the storage tank are increased. Since heat is exchanged with water, the heat energy of the combustion gas exiting the heat exchanger can be used to heat and decompress the pure water even if the pure water is frozen. By effectively utilizing the energy, the start-up and warm-up of the system can be completed early.
[0021]
According to the second and third aspects of the present invention, the pure water storage tank is disposed close to the combustor and the heat exchanger for burning the fuel gas when the temperature of the system is low, and the indirect heat transfer is also performed. In addition, thawing of pure water can be performed more efficiently.
[0022]
In the fourth to sixth inventions, the heat energy of the combustion gas is efficiently transmitted to the pure water by passing the combustion gas through the pure water storage tank or the heat exchange section adjacent to the bottom of the storage tank. Then, the thawing can be promoted, and in particular, in the sixth invention, the efficiency of heat transfer to pure water is enhanced by the heat transfer plate.
[0023]
In the seventh aspect, since the high-temperature combustion gas from the combustor is directly introduced into the storage tank, the pure water can be heated more rapidly.
[0024]
In the eighth invention, when the system is stopped, the pure water in the supply tank is dropped by gravity into the storage tank, and when the system is started, the pure water can be pushed up from the storage tank to the supply tank using the combustion gas pressure, By collecting pure water in only one storage tank when the system is stopped, damage to moving parts due to freezing of pure water can be easily avoided, and no special means is required to move pure water. In addition, the system can be simplified.
[0025]
According to the ninth aspect, the supply tank can be indirectly heated by using heat of the combustor, the heat exchanger, and the cooling system, and freezing of pure water can be avoided when the system is operated in a low temperature state.
[0026]
According to the tenth and eleventh aspects, when the temperature of the system is low, the cooling water is heated by the heat of the combustor and the heat exchanger, and the entire system can be quickly warmed up. The cooling water is radiated by the radiator to prevent the temperature of the fuel cell from rising excessively, and the pure water for humidifying the fuel gas and the oxidizing gas is heated to promote the evaporation of the humidified water, thereby promoting the fuel cell. Power generation efficiency can be improved.
[0027]
In the twelfth and thirteenth inventions, the storage tank functions as a silencer when discharging the combustion gas to the outside, so that noise mainly caused by vibration noise of the oxidizing gas supply system is effectively attenuated and reduced. In addition, quietness during system operation can be improved.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0029]
FIGS. 1 and 2 show a first embodiment. First, in FIG. 1, reference numeral 1 denotes a fuel cell main body, which includes a fuel electrode (anode) 2 and an air electrode (cathode) 3, and both electrodes have a solid height. Separated by molecular membranes. A cooling layer 4 for eliminating heat generated during power generation is provided inside the fuel cell body 1.
[0030]
Fuel cells include a type that directly supplies stored hydrogen gas and a type that supplies a hydrogen-rich gas by reforming a hydrocarbon-based fuel. In this embodiment, the type that holds the former hydrogen gas is used. Is illustrated.
[0031]
Reference numeral 5 denotes a hydrogen storage tank in which hydrogen gas is compressed and held in a high pressure state. The hydrogen gas is decompressed by the pressure regulating valve 6, humidified by pure water in the humidifier 7, and then supplied to the fuel electrode 2 of the fuel cell 1.
[0032]
On the discharge side of the fuel electrode 2, a circulation path 8 branches off from a branch portion 10 of the discharge side line via an ejector 9 in order to recirculate the exhaust gas containing excess hydrogen for the power generation reaction to the fuel electrode 2 again. The exhaust gas is returned to the upstream side of the humidifier 7 again.
[0033]
On the other hand, in order to supply air to the air electrode 3 of the fuel cell 1, there is provided a compressor 13 that takes in the air, compresses the air, and sends it to the air line. This compressed air also flows into the fuel cell 1 after being humidified by pure water in the humidifier 7.
[0034]
In the fuel cell 1, the hydrogen of the fuel electrode 2 and the oxygen of the air electrode 3 undergo an electrochemical reaction to generate power. The remaining exhaust gas from the air electrode 3 that has consumed oxygen by the reaction in the fuel cell 1 is introduced into the combustor 12. Exhaust gas containing excess hydrogen from the fuel electrode 2 is usually recirculated to the circulation path 8 to increase fuel consumption efficiency. However, the purge valve 11 provided downstream of the branch portion 10 is opened. At this time, the fuel is sent to the combustor 12, and at this time, the fuel burns with the air in the combustor 12.
[0035]
The purge valve 11 is closed during normal operation. However, when heat energy for heating is required, such as when the system is started at a low temperature, or when the power generation output request of the fuel cell 1 suddenly decreases, the purge valve 11 is closed. When the amount of hydrogen becomes excessive, when there is excessive water vapor in the hydrogen circulation system, or when the concentration of gas such as nitrogen gas permeating from the air electrode 3 that hinders the power generation reaction increases, Opened by a signal, exhaust gas containing excess hydrogen gas is introduced into the combustor 12.
[0036]
A catalyst 14 is disposed in the combustor 12, and when the purge valve 11 is opened and hydrogen gas is supplied, the catalyst reacts with oxygen in the exhaust gas from the air electrode 3 to generate heat. Note that an electrothermal catalyst is arranged upstream of the catalyst 14, and the catalyst works by energizing even at a low temperature start.
[0037]
Before starting the power generation in the fuel cell 1 such as when the system is at a temperature lower than the freezing point, the cooling water (antifreeze liquid) of the fuel cell 1 is generated by using the high-temperature gas generated by burning the hydrogen gas in the combustor 12. ), And when the pure water supplied for humidification in the reaction gas is frozen, it is thawed.
[0038]
For this reason, first, a heat exchanger 15 that heats the cooling water of the fuel cell 1 with the high-temperature gas from the combustor 12 is disposed downstream of the combustor 12. A part of the cooling water that has passed through the cooling layer 4 of the fuel cell 1 is guided to the heat exchanger 15 from the branch portion 27 through the passage 27a, where the cooling water is heated, thereby warming the entire system. It has become. Further, a storage tank 19 of pure water supplied to the humidifier 7 and the like is provided so as to be adjacent to the combustor 12 and the heat exchanger 15, and after the storage tank 19 has passed through the heat exchanger 15, Is heated, and the pure water in the storage tank 19 is heated and then discharged to the outside via the pressure regulating valve 25. However, these will be described later in detail.
[0039]
The fuel cell 1 is provided with the above-described cooling system that removes heat generated by the reaction of the fuel cell 1 during normal operation, and heats the system at a low temperature by being heated by the heat exchanger 15 described above. .
[0040]
A circulation pump 16 is provided in this cooling system, and during normal operation, cooling water from a radiator 17 is sent to the cooling layer 4 of the fuel cell 1 via the switching valve 18. More specifically, the cooling water heated by the cooling layer 4 flows from the branch portion 27 to the passage 27b, radiates heat by the radiator 17, and then raises the temperature of the hydrogen gas and the air gas by the humidifier 7 and then again. By being fed into the fuel cell 1, the temperature of the system is kept constant and the thermal energy required for humidification is supplied.
[0041]
On the other hand, when the system is started from a low temperature state, the switching valve 18 is switched by a signal from the controller 50 to change the circulation system, the passage 27a is connected to the suction side of the circulation pump 16, and the fuel cell 1 The cooling water that has flowed out flows all the way to the passage 27a, bypassing the radiator 17, and by passing through the heat exchanger 15, heat generated in the combustor 12 is given to the cooling water, and the fuel cell 1 and other The system is heated and heated. By using an antifreeze as the cooling water, it is possible to start the engine from below freezing.
[0042]
The switching valve 18 may be configured to automatically switch the operation by sensing the temperature of the cooling water. Even during the normal operation, the switching valve 18 guides a part of the cooling water to the side of the passage 27a, thereby enabling the catalyst 14 of the combustor 12 to operate. The temperature can be kept active. In this case, during normal operation in which the purge valve 11 is closed, cooling water that has been cooled and warmed by the fuel cell 1 passes through the combustor 12, and the catalyst 14 can be heated. Even if the saturated steam gas discharged from the air electrode 3 flows in, no condensed water is generated in the catalyst 14, and the function of the combustor 12 is not impaired.
[0043]
Next, as a pure water supply system for supplying pure water to the humidifier 7, a pure water supply tank 22 is provided, and a pump 23 supplies an injection valve 24 provided to the humidifier 7 via a supply passage 23 a. Pure water is sprayed on hydrogen and oxygen, which are reaction gases, and humidified. Although not shown, the injection valve 24 is provided independently so that pure water can be separately supplied to the hydrogen gas and the oxygen gas.
[0044]
Pure water generated at the air electrode 3 during power generation of the fuel cell 1 is collected in the supply tank 22 through the collection passage 28. The pure water recovery passage 28 and the supply passage 23a are arranged along the pipe of the cooling water for maintaining the temperature in a cold state, and receive heat from the cooling water that has passed through the fuel cell 1 and has increased in temperature. .
[0045]
A storage tank 19 for pure water is provided below and adjacent to the combustor 12 and the heat exchanger 15, and is connected to a supply tank 22 via a transfer pipe 20.
[0046]
The storage tank 19 is disposed below the supply tank 22. When the operation of the fuel cell 1 is stopped, the controller 50 opens the shutoff valve 21 provided in the transfer pipe 20 before stopping the supply pump 23 and the compressor 13. As a result, the pure water in the supply tank 22 is dropped into the pure water storage tank 19 using gravity, and the pure water remaining in the recovery passage 28 on the discharge side of the air electrode 3 is also supplied using air pressure. It can be collected in the storage tank 19 through the storage tank 22.
[0047]
The space above the supply tank 22 is communicated with the atmosphere by an air breather 22a, so that pure water can be normally pumped by the pump 23 and dropped into the storage tank 19 by gravity when stopped.
[0048]
As shown in FIG. 2, a pipe 30 through which the combustion exhaust gas flows from the combustor 12 via the heat exchanger 15 is connected to the storage tank 19. In addition, a bypass pipe 32 with a shutoff valve 26 that branches off from the middle of the pipe 30 and connects to the storage tank 19 is also connected between the combustor 12 and the heat exchanger 15.
[0049]
Further, the storage tank 19 is provided with an exhaust pipe 31 for discharging the exhaust gas to the outside, and the exhaust pipe 31 is provided with a pressure adjusting valve 25 so that the pressure of the exhaust gas in the storage tank 19 can be adjusted. Has become.
[0050]
The internal structure of the storage tank 19 is basically such that there are no moving parts such as pumps and valves inside the storage tank 19, and even if the pure water inside freezes, the moving parts are damaged. Not to be.
[0051]
The inside of the storage tank 19 is provided with a plurality of heat transfer plates 33 arranged in parallel, and the heat transfer plate 33 is partitioned so as to form a flow path 33a in which the inside meanders in parallel. The pipe 30 on the inlet side is connected to the storage tank 19 at the most upstream side of the meandering flow path 33a, and the exhaust pipe 31 on the outlet side is connected to the most downstream side.
[0052]
Therefore, when the operation of the fuel cell system is stopped, the controller 50 opens the shut-off valve 21 before stopping the supply pump 23 and the compressor 13 and drops the pure water in the supply tank to the storage tank 19 by gravity, Next, the pure water remaining in the recovery passage 28 is also returned from the supply tank 22 to the storage tank 19 using the air pressure.
[0053]
After the operation is stopped in this way, when the temperature drops below the freezing point and the pure water in the storage tank 19 freezes, the controller 50 starts up the system, and starts the high-temperature operation from the heat exchanger 15. The exhaust gas is introduced into the storage tank 19. The high-temperature exhaust gas flows in a meandering manner in the flow path 33a inside the storage tank 19 while increasing the flow velocity, and at this time, heat is applied to the pure water frozen and gradually thawed. In addition, since the high-temperature exhaust gas contains water vapor, it is cooled and condensed and liquefied, thereby increasing the amount of pure water.
[0054]
Due to the pressure regulating valve 25 provided in the exhaust pipe 31, the internal pressure of the storage tank 19 is maintained at a pressure higher than the atmospheric pressure, and as the pure water that has been frozen is melted, pure water that has accumulated below the tank is removed. Then, the transfer pipe 20 connected below the storage tank 19 flows backward and is pushed up to the supply tank 22 above.
[0055]
Since the transfer pipe 20 is connected below the storage tank 19, the liquefied pure water can be transferred to the supply tank 22 promptly and, if necessary, to the supply tank 22. Further, since the transfer pipe 20 is piped along the outer wall of the storage tank 19, even if there is frozen pure water in a part of the transfer pipe 20, the transfer pipe 20 easily receives the exhaust heat from the storage tank 19 and melts.
[0056]
In this case, when the shut-off valve 26 upstream of the heat exchanger 15 is opened, the higher temperature combustion gas reacted in the combustor 12 can be directly led to the storage tank 19, so that the thawing of the frozen pure water can be promoted. it can.
[0057]
When the water level sensor (not shown) provided in the supply tank 22 detects that the water level has reached a predetermined value, the controller 50 closes the shut-off valve 21 of the transfer pipe 20 so that the supply tank 22 can return from the supply tank 22 in the same manner as during normal operation. Pure water can be supplied.
[0058]
The ratio of the latent heat of fusion for thawing pure water to the heat energy required to start the fuel cell system is relatively large. To shorten the start-up time, the heat energy generated in the combustor 12 is reduced by the cooling water. Therefore, it is necessary to appropriately distribute the system heating and the defrosting of the purified pure water through the system. For this purpose, the opening and closing of the shut-off valve 21 is controlled while monitoring the water level of the supply tank 22 and the temperature of the cooling system of the system. ing.
[0059]
When the water level in the supply tank 22 reaches the specified value, the shutoff valve 21 is closed to stop the introduction of pure water from the storage tank 19 to the supply tank 22. Can be stored as is. When the liquid level of the supply tank 22 drops below a specified value as pure water for humidification is supplied from the humidifier 7 by the shift to the normal operation of the system, the shut-off valve 21 is opened again, and the inside of the storage tank 19 is opened. Pure water can be pushed up and supplied to the supply tank 22 using the internal pressure.
[0060]
In the storage tank 19, when the system is warmed up, the high-temperature exhaust gas flows in a meandering manner in the meandering flow path 33a while increasing the flow velocity. Since the exchange of heat with water is also promoted, thawing can be performed efficiently.
[0061]
On the other hand, during normal operation, most of the internal space of the storage tank 19 serves as an exhaust gas passage, and the heat transfer plate 33 functions as a baffle plate for the exhaust gas, reduces the exhaust pressure, and reduces the pressure of the supercharger 13. It also has the function of reducing the generated pressure pulsation, and can also function as an exhaust silencer.
[0062]
Next, a second embodiment will be described with reference to FIGS.
[0063]
The second embodiment is different from the first embodiment mainly in the structure of a storage tank of pure water.
[0064]
That is, the storage tank 40 has a layered heat exchange section 44 on its lower surface, and the exhaust gas flows into the heat exchange section 44 and is discharged to the outside from the exhaust pipe 45. The exhaust pipe 45 is provided with a pressure adjusting valve 25, and adjusts the internal pressure of the storage tank 40 and the heat exchange unit 44 in the same manner as described above.
[0065]
The exhaust gas from the heat exchanger 15 flows into the heat exchange unit 44 via the pipe 41, but a part of the exhaust gas flows into the storage tank 40 via the branch pipe 43 branched from the pipe 41. However, the storage tank 40 does not have an outlet for exhaust gas, and only the pressure of the pipe 41 is transmitted to the storage tank 40.
[0066]
The storage tank 40 is connected to the upper supply tank 22 via the transfer pipe 20. When the system is stopped, pure water from the supply tank 22 drops, and when the system is started, the decompressed pure water is supplied to the supply tank 22 by internal pressure. Push up.
[0067]
A plurality of heat transfer plates 46 are erected from the bottom surface of the storage tank 40 so as to form a meandering flow path in parallel, thereby facilitating the transfer of heat from the lower heat exchange unit 44 into the storage tank 40. are doing. Above the storage tank 40, a pipe 32 for directly introducing high-temperature combustion gas when the shutoff valve 26 on the upstream side of the heat exchanger 15 is opened is connected.
[0068]
With such a configuration, when the system is started, high-temperature exhaust gas flows from the heat exchanger 15 into the heat exchange unit 44 via the pipe 41, and thereby heats the storage tank 40 from the bottom surface side. The heat transfer plate 46 erected on the bottom surface of the storage tank 40 comes into contact with pure water and directly transfers exhaust heat. Thereby, the frozen pure water in the storage tank 40 receives the heat and is quickly thawed. If necessary, the shutoff valve 26 is opened and the high-temperature combustion gas from the combustor 12 is directly injected into the storage tank 40. In this way, heat is simultaneously received from the upper surface and the lower surface in the storage tank, and the pure water frozen inside can be rapidly thawed.
[0069]
The internal pressure of the storage tank 40 is maintained at or above the atmospheric pressure by the pressure regulating valve 25 in the same manner as the internal pressure of the heat exchange section 44. Therefore, pure water dissolved from the bottom of the storage tank 40 is transferred to the upper part by the transfer pipe 20. It is pushed up to the supply tank 22.
[0070]
In this way, since the purified pure water is sequentially pushed out from the bottom of the storage tank 40, the efficiency of heat transfer is good, and the supply of pure water from the supply tank 22 to the humidifier 7 can be started earlier. Become.
[0071]
When the system shifts to the normal operation after the start of the system, the pure water remaining in the storage tank 40 disappears or becomes very small. At this time, all of the exhaust gas is discharged from the pipe 41 to the outside via the heat exchange unit 44, but the pressure of the exhaust gas passing through the pipe 41 through the branch pipe 43 is formed in the closed internal space in the storage tank 40. Waves are transmitted.
[0072]
Now, assuming that the volume of the internal space of the storage tank 40 is V, the length of the branch pipe 43 is L, and the inside diameter is D, the storage tank 40 is a Hertzholm type silencer with respect to the pipe 41 through which exhaust gas flows. Can function as
[0073]
Therefore, if the rotational frequency of the supercharger 13 in the air supply system and the vibration frequency of the noise determined by the piping system are F,
F = K ｛{D / (L ・ V)} ^1/2
However, by setting each of D, L, and V such that K is a value that satisfies the coefficient affected by the speed of sound in the exhaust gas, it is possible to exhibit a noise-canceling effect on the noise at the frequency F. .
[0074]
As described above, according to the present embodiment, even when pure water is frozen when the system is stopped, the operating parts are not damaged by the freezing, and the heat energy generated in the combustor at the time of starting the system is used to raise the temperature of the system. It can be effectively used for thawing warm and frozen pure water, and it is possible to shorten the time until the start of the system and to reduce energy consumption. In addition, it can contribute to reduction of noise of the air supply system during normal operation.
[0075]
It is apparent that the present invention is not limited to the above-described embodiment, and that various changes can be made within the scope of the technical idea.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a configuration of a first embodiment of the present invention.
FIG. 2 is a perspective explanatory view showing a part of the storage tank.
FIG. 3 is a schematic diagram illustrating a configuration of a second embodiment.
FIG. 4 is a perspective explanatory view showing a part of the storage tank.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel cell main body 2 Fuel electrode 3 Air electrode 5 Hydrogen storage tank 7 Humidifier 8 Circulation line 11 Purge valve 12 Combustor 15 Heat exchanger 16 Circulation pump 19 Storage tank 20 Transfer pipe 21 Shutoff valve 22 Supply tank 23 Pump 25 Exhaust Throttle valve 26 Shut-off valve 30 Pipe 31 Exhaust pipe 33 Heat transfer plate

Claims (13)

In a fuel cell system for generating electricity by electrochemically reacting a fuel gas containing hydrogen and an oxidizing gas containing oxygen,
A fuel cell body having a fuel electrode and an air electrode,
Means for supplying pure water for humidification to the oxidizing gas and the fuel gas to be supplied to the fuel electrode and the air electrode,
A cooling system for cooling the fuel cell body with cooling water,
A heat exchanger that heats the cooling water by a combustion gas obtained by burning a part of the fuel gas and the oxidizing gas at a low temperature of the system,
A tank for storing the pure water for humidification,
Heat exchange means for exchanging heat between the combustion gas discharged from the heat exchanger and pure water stored in the storage tank,
A fuel cell system comprising: A combustor for burning a part of the fuel gas discharged from the fuel cell main body and the oxidizing gas is provided upstream of the heat exchanger. The fuel cell system according to claim 1, wherein the storage tank of the pure water is disposed as possible. 3. The fuel cell system according to claim 2, wherein a fuel exhaust gas from a fuel electrode of the fuel cell main body is introduced into the combustor via a purge valve at a low temperature of the system. 4. The fuel cell system according to claim 1, wherein the heat exchange unit is configured to allow the combustion gas to pass through the inside of the storage tank and apply heat to pure water. 5. 4. The heat exchange unit according to claim 1, wherein a heat exchange unit is provided adjacent to a bottom surface of the storage tank, and the combustion gas is passed through the heat exchange unit. The fuel cell system according to item 1. The fuel cell system according to claim 4, wherein a plurality of heat transfer plates that transfer heat from the combustion gas to pure water are arranged in the storage tank. The fuel cell system according to claim 4, wherein a combustion gas from the combustor is directly introduced into the storage tank via a shutoff valve. A tank for supplying the pure water for humidification is provided above the storage tank, and a shutoff valve is provided in a pipe connecting the tank and the storage tank to discharge the combustion gas to the outside. An exhaust throttle valve is provided to throttle before the system is closed.When the system is stopped, the shutoff valve is opened to recover pure water from the upper tank to the storage tank.When the system is started, the exhaust throttle valve is throttled and the shutoff valve is opened. The fuel cell system according to any one of claims 2 to 7, wherein pure water is pushed up and transferred to an upper tank by exhaust pressure. 9. The combustion battery system according to claim 8, wherein the pure water supply tank is arranged near at least one of the combustor, the heat exchanger, and the cooling system to exchange heat. A switching valve is provided for switching between cooling water of the cooling system after passing through the fuel cell main body, flowing into the circulation pump via the combustor and the heat exchanger, and flowing into the circulation pump via the radiator. 4. The fuel cell system according to claim 2, wherein cooling water is circulated through the combustor and the heat exchanger when the temperature of the system is low. The fuel cell system according to claim 10, wherein the cooling water discharged from the circulation pump flows to the pure water supply unit before flowing into the fuel cell main body. 7. The fuel cell system according to claim 6, wherein the storage tank functions as a combustion gas silencer to attenuate and reduce pressure pulsation. The fuel cell system according to claim 5, wherein the pressure of the combustion gas flowing through the heat exchange unit is connected to the storage tank via a pipe so that the storage tank functions as a Helmholtz silencer.

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