JP2005116368A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact fuel cell system by eliminating the need for arranging a fuel cell and a combustor apart from each other to protect the fuel cell from heat. <P>SOLUTION: The fuel cell system comprises a fuel cell 3 for generating power by using fuel gas and oxidant gas, a water tank 25 for storing water for supplying to the fuel cell 3 as a reaction assistant, and a combustor 7 for combusting mixed gas of the fuel gas or anode gas, and the oxidant gas or cathode gas. The water tank 25 is arranged between the fuel cell 3 and the combustor 7. The water tank 25 functions as a heat insulator between the fuel cell 3 and the combustor 7, allowing the fuel cell 3 and the combustor 7 to be disposed nearby across the water tank 25. Accordingly, a compact fuel cell system can be achieved without using a separate heat insulator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system, and more particularly, a fuel cell system including a combustor that burns anode supply gas (fuel gas) or anode off gas and a water tank that stores water supplied as a reaction aid to the fuel cell. About.

  As disclosed in Patent Document 1, the fuel cell system is a fuel cell, in which a fuel gas such as hydrogen gas (anode supply gas) and an oxidizing gas containing oxygen (cathode supply gas) are electrochemically passed through an electrolyte. Electric energy is directly taken out from between electrodes provided on both surfaces of the electrolyte by reaction. In particular, solid polymer fuel cells using solid polymer electrolytes are attracting attention as power sources for electric vehicles because of their low operating temperature and easy handling. In other words, the fuel cell vehicle has a hydrogen storage device mounted on the vehicle, hydrogen supplied from the vehicle, and oxygen-containing air are sent to the fuel cell for reaction, and the electric energy extracted from the fuel cell is connected to the driving wheel. It is the ultimate clean vehicle that drives the motor and only emits water.

  Usually, the polymer electrolyte fuel cell used on the ground supplies air to the oxidizer electrode. Part of this nitrogen in the air leaks from the polymer electrolyte membrane, reaches the fuel electrode from the oxidizer electrode, and accumulates in the fuel gas circulation path. In addition, when chemical by-product hydrogen gas is used as the fuel gas, impurities in the hydrogen gas accumulate in the fuel gas circulation path. When such impurities such as nitrogen accumulate in the fuel gas circulation path, the partial pressure of the fuel gas supplied to the fuel electrode decreases, so that the power generation efficiency decreases.

For this reason, a purge operation is performed to discharge the fuel gas having an increased impurity concentration in the fuel gas circulation path to the outside of the circulation path every certain time or after generating a certain amount of power. However, since it is not preferable to discharge the purge gas containing hydrogen into the atmosphere as it is, it is discharged outside the system after being burned in a combustor equipped with a combustion catalyst. The combustor may be used for thawing pure water frozen by burning fuel gas and starting the fuel cell system.
Japanese Unexamined Patent Publication No. 2000-306594

  Such a combustor is generally operated at a combustion temperature of 500 ° C. or higher in order to facilitate combustion. On the other hand, in the case of a polymer electrolyte fuel cell, for example, the fuel cell is operated in the range of room temperature to 80 ° C. or less because the solid polymer electrolyte membrane is vulnerable to high heat.

  Therefore, in order to protect the fuel cell from heat, it is necessary to dispose the fuel cell and the combustor separately, and it is difficult to fit the fuel cell system in a compact manner.

  In order to solve the above-described conventional problems, the present invention provides a fuel cell that generates power using a fuel gas as an anode supply gas and an oxidant gas as a cathode supply gas, and supplies the fuel cell as a reaction aid. A combustor for burning a mixed gas of a water tank for storing water, an anode off-gas discharged from the fuel gas or the anode of the fuel cell, and an oxidant gas or a cathode off-gas discharged from the cathode of the fuel cell; A fuel cell system comprising: the water tank is disposed between the fuel cell and the combustor.

  According to the present invention, the water tank functions as a heat shield between the fuel cell and the combustor, whereby the fuel cell and the combustor can be disposed close to each other with the water tank interposed therebetween. As a result, the fuel cell system can be made compact without arranging a separate heat shield.

  Hereinafter, an embodiment of a fuel cell system according to the present invention will be described in detail with reference to FIGS. 1 and 2. The fuel cell system of this embodiment is applied to a fuel cell vehicle, and is mounted under the floor of a vehicle as a movable body and used as a drive source of the vehicle. First, the outline of the fuel cell system of this embodiment will be described.

"Overall configuration of fuel cell system"
FIG. 1 is a system configuration diagram of the fuel cell system of this embodiment. In FIG. 1, the fuel cell system includes a hydrogen supply device (fuel gas supply device) 1 that supplies hydrogen as a fuel gas via a hydrogen supply pipe 11, and air as an oxidant gas via an air supply pipe 14. An air supply device (oxidant gas supply device) 2 to be supplied, an anode (fuel electrode) 4 and a cathode (oxidant electrode) 5 as electrodes, and a fuel that generates electricity using hydrogen and oxygen supplied to each electrode The refrigerant is heated by the battery 3, the anode offgas circulation device 6 that circulates the anode offgas upstream of the anode 4 through the anode offgas circulation pipe 12, the combustor 7 that combusts the anode offgas, and the combustion exhaust gas of the combustor 7. The refrigerant heat exchanger 8, the refrigerant cooling device 9, the humidifier 10A for humidifying hydrogen as the anode supply gas, and the air as the cathode supply gas are humidified. Heat exchange is performed between the humidifier 10B, the air flow rate control valve 16, the refrigerant pump 21 that circulates the refrigerant in the refrigerant flow path 20 between the heat exchanger 8 or the refrigerant cooling device 9 and the fuel cell 3, and the refrigerant flow path 20. A three-way valve 22 for switching to the combustor 8 or the refrigerant cooling device 9, an anode off-gas discharge valve 27 for discharging the anode off-gas from the anode off-gas circulation device 6 to the combustor 7 via the anode off-gas discharge pipe 13, and the entire fuel cell system. System controller 37.

  In this embodiment, the configuration of the humidifier 10A for anode supply gas and the humidifier 10B for cathode supply are different, and the humidifier 10A for anode supply gas uses water stored in the water tank 25. Then, the hydrogen flowing through the hydrogen supply pipe 11 is humidified. On the other hand, the humidifier 10B for the cathode supply gas has an assembly of hollow fiber membranes inside, and distributes the cathode off gas inside the hollow fiber membrane and distributes the cathode supply gas outside the hollow fiber membrane. The cathode supply gas is humidified with moisture in the off gas. Considering the cathode offgas side as a main component, the cathode offgas is dehumidified by absorbing moisture into the cathode supply gas.

  Here, the water tank 25 collects and stores the water condensed in the fuel cell 3, the humidifier, the combustor 7, the heat exchanger 8, the exhaust pipe 19, and the like through a pipe (not shown).

"Operation of the fuel cell system"
Next, the operation of the fuel cell system will be described.

  First, hydrogen from the hydrogen supply device 1 is humidified by the humidifier 10A and supplied to the anode 4, and air from the air supply device 2 is humidified by the humidifier 10B and supplied to the cathode 5, and these hydrogen and air are supplied. The fuel cell 3 reacts to generate electricity. At that time, the anode 4 which is not consumed and is left out is discharged from the anode 4. Also, a part of oxygen is consumed from the cathode 5 and cathode off gas containing moisture generated by power generation is discharged.

  During normal operation, the anode off-gas is circulated through the anode off-gas circulation pipe 6 through the anode off-gas circulation pipe 12 to the hydrogen supply pipe 11 and supplied to the anode 4 again. On the other hand, the cathode off-gas is exhausted out of the system through the humidifier 10B, the combustor 7, the refrigerant heat exchanger 8, and the exhaust pipe 19.

  Here, when a voltage lower than a predetermined voltage value is detected by the voltage detection means for detecting the cell voltage of the fuel cell 3, a purge signal is transmitted from the system controller 37, and based on this purge signal, the anode A predetermined flow rate of anode off-gas is discharged from the off-gas discharge valve 27 to the combustor 7.

  In the combustor 7, the anode offgas (exhaust hydrogen) supplied via the anode offgas discharge valve 27 is mixed with the cathode offgas by the mixer 23, and this mixed gas is combusted in the combustion chamber 24 having a combustion catalyst. The combustion gas generated in the combustor 7 passes through the refrigerant heat exchanger 8 and is exhausted outside the system (atmosphere) through the exhaust pipe 19.

  The combustor 7 can be supplied with hydrogen from the hydrogen supply device 1 through a pipe (not shown) and can be supplied with air through a pipe (not shown) to process the purged exhausted hydrogen. In addition to the time, heat can be generated by burning hydrogen and air (oxygen). Using this combustion heat, the fuel cell 3 can be heated as required.

"Fuel cell temperature control"
Next, temperature management of the fuel cell 3 will be described. The temperature of the fuel cell 3 is controlled so that the operating temperature is maintained at an appropriate temperature by a refrigerant such as antifreeze.

  During normal operation of the fuel cell system, it is necessary to keep the heated fuel cell 3 cooled to an appropriate operating temperature. Therefore, the refrigerant pump 21 and the refrigerant cooling device 9 are communicated with each other by the three-way valve 22 so that the refrigerant is circulated in the closed circuit of the refrigerant pump 21, the three-way valve 22, the refrigerant cooling device 9, the fuel cell 3, and the refrigerant pump 21. It has become. As a result, the heat generated in the fuel cell 3 is released from the refrigerant cooling device 9 to the outside of the system, and the temperature of the fuel cell 3 is maintained at an appropriate temperature.

  On the other hand, when starting the fuel cell system, it is necessary to raise the fuel cell 3 to an appropriate operating temperature. Therefore, by connecting the refrigerant pump 21 and the refrigerant heat exchanger 8 with the three-way valve 22, the refrigerant is closed to the refrigerant pump 21, the three-way valve 22, the refrigerant heat exchanger 8, the fuel cell 3, and the refrigerant pump 21. It is designed to circulate. As a result, the medium used as the refrigerant during normal operation can be used as the heating medium, and the temperature of the fuel cell 3 is increased to an appropriate temperature for starting operation by increasing the temperature of the heating medium with the refrigerant heat exchanger 8. Can do.

"Layout layout of fuel cell and combustor"
Next, the layout of the fuel cell and the combustor will be described with reference to FIG. FIG. 2 is a plan view showing the vicinity of the fuel cell and the combustor.

  Reference numeral 30 in FIG. 2 denotes a frame fixed to the vehicle body under the floor below the front seat. In this frame 30, the exhaust system components (humidifier 10B, combustor 7, refrigerant heat exchanger 8, exhaust pipe 19 and the like) mainly including the fuel cell 3 and the combustor 7 are sub-assembled. The mounting is fixed. Note that a hydrogen tank (not shown) and a secondary battery (not shown) for storing electricity generated by the fuel cell 3 and a system controller 37 are fixedly attached to another frame (not shown) below the floor behind the fuel cell 3. .

  As shown in FIG. 2, a water tank 25 functioning as a heat shield is disposed between the combustor 7 and the fuel cell 3 having greatly different operating temperatures. As for the arrangement relationship of the combustor 7, the water tank 25, and the fuel cell 3, the combustor 7, the water tank 25, and the fuel cell 3 are arranged close to each other in order from the front to the rear of the vehicle. The humidifier 10 </ b> B for cathode supply gas is disposed in front of the vehicle with respect to the fuel cell 3 and on the side of the vehicle with respect to the combustor 7 and the water tank 25. As described above, the humidifier 10B for cathode supply gas receives the heat of the combustor 7 by being disposed in the vicinity of the combustor 7, and can prevent condensation of moisture flowing through the humidifier 10B, and further freezing. Can be prevented. Further, since the humidifier 10B for the cathode supply gas is arranged in the vehicle width direction with respect to the combustor 7, the humidifier 10B is not directly exposed to combustion heat due to the influence of the traveling wind, and is generally a hollow with low heat resistance. The yarn membrane can be reliably protected.

"effect"
Hereinafter, the effects of the fuel cell system of this embodiment will be summarized.

  First, the fuel cell system is characterized in that the water tank 25 is disposed between the fuel cell 3 and the combustor 7, so that the water tank 25 is disposed between the fuel cell 3 and the combustor 7. Thus, the fuel cell 3 and the combustor 7 can be disposed close to each other with the water tank 25 interposed therebetween. As a result, the fuel cell system can be made compact without arranging a separate heat shield. In this example, the vehicle can be made compact in the longitudinal direction. Further, since the water tank 25 can be heated by using the combustion heat of the combustor 7, it is advantageous for defrosting in the water tank 25 and in the piping around the water tank 25 when the temperature is below freezing. Further, since the fuel cell 3 can also be heated through the water tank 25, it is advantageous for heating the fuel cell 3.

  Secondly, the fuel cell system is mounted on a vehicle as a movable body so that the fuel cell system is a movable power generator, and the movable body is moved from the front (front of the vehicle) to the rear in the main movement direction. Since the combustor 7, the water tank 25, and the fuel cell 3 are arranged in this order, heat can be transmitted to the water tank 25 and the fuel cell 3 more efficiently using the traveling wind. In general, a part of the traveling wind also enters the floor under a small amount, so that a part of the traveling wind can be used.

  Thirdly, according to this fuel cell system, the humidifier 10B has a water-permeable hollow fiber membrane, allows water to flow through either the inside or outside of this hollow fiber membrane, and humidifies the other. The humidifying gas is humidified by circulating the gas, and the humidifier 10B is arranged on the side of the movable body in the main movement direction (vehicle width direction) with respect to the water tank 25 and the combustor 7. Therefore, the humidifier 10B and the combustor 7 can be disposed close to each other, and the heat of the combustor 7 is received by the humidifier 10B so that the water flowing through the humidifier 10B is not condensed or frozen. In addition, since the humidifier 10B is disposed on the side of the movable body in the main movement direction (vehicle width direction) with respect to the combustor 7, the variation in the amount of heat received due to the influence of the traveling wind can be suppressed as much as possible. A low hollow fiber membrane can be reliably protected.

  Fourth, according to this fuel cell system, the humidifier 10B is further moved forward of the movable body in the main movement direction (front of the vehicle) with respect to the fuel cell 3 and with respect to the combustor 7 and the water tank 25. Since it arrange | positions to the main movement direction side (vehicle width direction), it can be made compact also with respect to the main movement direction side (vehicle width direction) of a movable body. Therefore, it can be arranged most compactly in the vehicle front-rear left-right direction.

  Fifth, according to this fuel cell system, the humidifier 10B is a humidifier 10B for cathode supply gas, and this cathode supply gas humidifier 10B is a fuel cell on either the inside or the outside of the hollow fiber membrane. 3, the cathode supply gas is circulated to the other side, and the cathode supply gas is circulated to the other side to humidify the cathode supply gas with moisture contained in the cathode offgas. As shown in FIG. 2, (1) humidification for cathode supply gas because the movable body is disposed in front of the moving direction (front of the vehicle) and on the side of the movable body in the main moving direction (vehicle width direction) with respect to the combustor 7 and the water tank 25. Piping 14 for sending the cathode supply gas from the battery 10B to the fuel cell 3, and (2) a distribution for sending the cathode off-gas exhausted from the fuel cell 3 to the humidifier 10B for the cathode supply gas. 15 and (3) the piping for sending the cathode off gas from the cathode supply gas humidifier 10B to the combustor 7 can be set short, so that the piping structure can be simplified and the fuel cell system can be made more compact. .

  Further, since the humidifier 10B and the combustor 7 in the upstream / downstream relationship with the cathode offgas exhaust passage can be sub-assembled in advance, the assembly of the fuel cell system is also improved.

  Sixth, according to this fuel cell system, since the movable body is a vehicle, the fuel cell 3 can be used as a power source for driving the vehicle, which is suitable as a fuel cell vehicle.

  In short, the fuel cell system of the present invention is characterized in that a water tank is disposed between the fuel cell and the combustor, so that the water tank serves as a heat shield between the fuel cell and the combustor. The fuel cell and the combustor can be disposed close to each other with the water tank interposed therebetween. As a result, the fuel cell system can be made compact without arranging a separate heat shield.

  In the above embodiment, the water tank 25 stores the condensed water generated in the system and supplies the stored water to the anode supply gas humidifier 10A. However, in the present invention, the water tank 25 is used. It is also possible to supply water to other components. Moreover, you may change another structure in the range which does not deviate from the technical idea of this invention.

1 is a system configuration diagram showing a first embodiment of a fuel cell system according to the present invention. The top view which shows the arrangement layout of the vicinity of the fuel cell and combustor of the fuel cell system in 1st Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 ... Fuel cell 4 ... Anode 5 ... Cathode 7 ... Combustor 10B ... Humidifier (humidifier) for cathode supply gas
25 ... Water tank

Claims (6)

A fuel cell that generates power using a fuel gas as an anode supply gas and an oxidant gas as a cathode supply gas;
A water tank for storing water supplied as a reaction aid to the fuel cell;
A combustor that burns a mixed gas of the fuel gas or an anode off-gas discharged from the anode of the fuel cell and an oxidant gas or a cathode off-gas discharged from the cathode of the fuel cell;
A fuel cell system comprising:
A fuel cell system, wherein the water tank is disposed between the fuel cell and the combustor. The fuel cell system according to claim 1, wherein
By mounting the fuel cell system on a movable body, the fuel cell system is configured as a movable power generator,
The fuel cell system, wherein the combustor, the water tank, and the fuel cell are arranged in this order from the front to the rear in the main moving direction of the movable body. The fuel cell system according to claim 2, wherein
A humidifier for humidifying the cathode supply gas and / or the anode supply gas as the humidified gas,
The humidifier has a water-permeable hollow fiber membrane and circulates moisture through either the inside or outside of the hollow fiber membrane, and circulates humidified gas through the other to humidify the humidified gas. Structure to
The fuel cell system, wherein the humidifier is disposed on the side of the movable body in the main movement direction with respect to the water tank and the combustor. The fuel cell system according to claim 3, wherein
The fuel cell is characterized in that the humidifier is disposed in front of the movable body in the main movement direction with respect to the fuel cell and laterally in the main movement direction of the movable body with respect to the combustor and the water tank. system. The fuel cell system according to claim 4, wherein
The humidifier is a humidifier for cathode supply gas,
The humidifier for the cathode supply gas causes the cathode offgas from the fuel cell to flow through either the inside or the outside of the hollow fiber membrane and the cathode supply gas to flow through the other to form the cathode with moisture contained in the cathode offgas. A fuel cell system characterized by humidifying a supply gas. The fuel cell system according to any one of claims 1 to 5,
The fuel cell system, wherein the movable body is a vehicle.