JP2006032147A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out a low temperature start-up speedily by a simple and economical constitution. <P>SOLUTION: A fluid circulation device 46 for temperature control has a combustor 68 to burn a reactant gas and heat the fluid for temperature control, a fluid supply tube passage 70 for temperature control to warm up a fuel cell stack 12 by the fluid for temperature control heated by the combustor 68, a first waste heat gas supply passage 86 to warm up at least auxiliary equipment by the waste heat gas discharged from the combustor 68, and a second waste heat gas supply passage 94 to warm up an electricity storing device 96 by the waste heat gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a fuel cell stack in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is provided with a power generation cell sandwiched between separators, and a plurality of the power generation cells are stacked, and the fuel cell stack is operated. The present invention relates to a fuel cell system that includes auxiliary devices used to perform storage and a power storage device capable of storing and supplying electric energy.

  Generally, a polymer electrolyte fuel cell includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) in which an anode side electrode and a cathode side electrode are provided on both sides of an electrolyte membrane (electrolyte) made of a polymer ion exchange membrane, respectively. A power generation cell sandwiched by a separator. This type of power generation cell is normally used as a fuel cell stack by alternately laminating a predetermined number of electrolyte membrane / electrode structures and separators.

  In a fuel cell, a fuel gas, for example, a gas mainly containing hydrogen (hereinafter also referred to as a hydrogen-containing gas) is supplied to the anode side electrode, while an oxidant gas, for example, a main gas is supplied to the cathode side electrode. Is supplied with oxygen-containing gas or air (hereinafter also referred to as oxygen-containing gas). In the fuel gas supplied to the anode side electrode, hydrogen is ionized on the electrode catalyst and moves to the cathode side electrode side through the electrolyte membrane. Electrons generated during that time are taken out to an external circuit and used as direct current electric energy.

  By the way, in this type of fuel cell, in order to maintain ionic conductivity, it is necessary to appropriately humidify the electrolyte membrane made of the polymer ion exchange membrane. Furthermore, while water generated by the reaction exists as described above in the cathode side electrode, the generated water tends to be reversely diffused in the anode side electrode. For this reason, it has been pointed out that when the fuel cell is started at a low temperature such as below freezing point, the moisture in the fuel cell is likely to be frozen and the electrochemical reaction is difficult to occur in the fuel cell.

  In order to solve this type of problem, for example, a polymer electrolyte fuel cell power generation system disclosed in Patent Document 1 is known. As shown in FIG. 6, this polymer electrolyte fuel cell power generation system includes a fuel cell stack 1, and this fuel cell stack 1 contains oxidant gas from oxidant gas supply means 2, for example, air. While being supplied, fuel gas, for example, hydrogen gas is supplied from the fuel gas supply means 3.

  An antifreeze liquid is circulated and supplied to a cooling plate (not shown) constituting the fuel cell stack 1 through an antifreeze supply means 4. The antifreeze liquid supply means 4 includes an antifreeze liquid pump 5. The antifreeze liquid is supplied from the antifreeze liquid pump 5 to the antifreeze liquid heating means 6. The antifreeze liquid is heated by the antifreeze liquid heating means 6 and then supplied to the fuel cell stack 1. Then, the fuel cell stack 1 is warmed up.

  The antifreeze liquid heating means 6 includes a combustor 6a and a heat exchanger 6b for exchanging heat between the combustion waste gas from the combustor 6a and the antifreeze liquid. The antifreeze heating means 6 is provided with a combustion waste gas supply path 7 for supplying combustion waste gas, and the combustion waste gas supply path 7 is a combustion provided so as to surround the fuel cell stack 1. It communicates with the waste gas distribution channel 8.

  For this reason, the combustion waste gas discharged from the antifreeze liquid heating means 6 is guided to the combustion waste gas distribution path 8 through the combustion waste gas supply path 7, and the fuel cell stack 1 is heated in the combustion waste gas distribution path 8. After that, it is discharged to the outside.

JP 2000-164233 A (FIG. 2)

  Generally, in the polymer electrolyte fuel cell power generation system described above, power is supplied to auxiliary devices particularly when the fuel cell stack 1 is started up, and electric energy generated by the fuel cell stack is stored as necessary. Therefore, power storage devices such as capacitors and batteries are used.

  However, it is known that the output of the power storage device varies depending on the temperature, and the output decreases as the temperature decreases. For this reason, in the structure in which only the periphery of the fuel cell stack 1 is heated as in Patent Document 1, the polymer electrolyte fuel cell power generation system is successfully started in a short time due to a decrease in the output of the power storage device at low temperatures. There is a problem that cannot be made.

  In addition, the auxiliary devices of the fuel cell stack 1 may freeze at the time of cold start. Thereby, in patent document 1, considerable time is required for warming up auxiliary devices, and there exists a problem that a low-temperature start cannot be performed rapidly.

  An object of the present invention is to solve this type of problem, and an object thereof is to provide a fuel cell system capable of promptly performing a cold start with a simple and economical configuration.

  The present invention provides a fuel cell stack in which an electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is provided with a power generation cell sandwiched between separators, and a plurality of the power generation cells are stacked, and the fuel cell stack is operated. And a power storage device capable of storing and supplying electrical energy, wherein the fuel cell system is configured to circulate a temperature adjusting fluid in the fuel cell stack. A conditioning fluid circulation device is provided.

  The temperature adjustment fluid circulation device includes a combustor that heats the temperature adjustment fluid by burning a reaction gas used for a power generation reaction of a power generation cell, and waste heat that is discharged from the combustor when the temperature adjustment fluid is heated. A first waste heat gas supply passage for supplying gas to at least the auxiliary devices to warm up the auxiliary devices; and a second waste heat gas for supplying the waste heat gas to the power storage device to warm up the power storage device. A waste heat gas supply path is provided.

  Moreover, it is preferable that a 2nd waste heat gas supply path is comprised by the cooling duct used in order to cool an electrical storage apparatus. Furthermore, it is preferable to provide a heat exchanging means for raising the temperature of the passenger compartment using waste heat gas.

  According to the present invention, it is possible to quickly warm up the auxiliary devices and the power storage device using the waste heat gas discharged from the combustor, and to defrost the auxiliary devices and improve the output characteristics of the power storage device. Is easily achieved. This makes it possible to improve the low temperature starting characteristics of the fuel cell system with a simple and economical configuration.

  FIG. 1 is an explanatory diagram of a schematic configuration of a fuel cell system 10 according to a first embodiment of the present invention. A fuel cell stack 12 constituting the fuel cell system 10 includes a plurality of power generation cells 14 in the direction of arrow A. It is constructed by stacking.

  The power generation cell 14 includes an electrolyte membrane / electrode structure (electrolyte / electrode structure) 16, and first and second metal separators 18 and 20 that sandwich the electrolyte membrane / electrode structure 16. The electrolyte membrane / electrode structure 16 includes, for example, a solid polymer electrolyte membrane 22 in which a perfluorosulfonic acid thin film is impregnated with water, and an anode-side electrode 24 and a cathode that sandwich and hold the solid polymer electrolyte membrane 22 Side electrode 26. Instead of the first and second metal separators 18 and 20, for example, a carbon separator (not shown) may be used.

  The anode side electrode 24 and the cathode side electrode 26 are uniformly coated on the surface of the gas diffusion layer with a gas diffusion layer (not shown) made of carbon paper or the like, and porous carbon particles with a platinum alloy supported on the surface. And an electrode catalyst layer (not shown).

  Between the first metal separator 18 and the anode side electrode 24, a fuel gas flow path 28 for supplying fuel gas along the anode side electrode 24 is formed. Between the second metal separator 20 and the cathode side electrode 26, an oxidant gas flow path 30 for supplying an oxidant gas along the cathode side electrode 26 is formed. Between the first and second metal separators 18 and 20, a temperature adjustment fluid channel 32 for supplying a temperature adjustment fluid for adjusting the temperature of the power generation cell 14, mainly for cooling, is formed.

  End plates 34a and 34b are disposed at both ends of the fuel cell stack 12, and a clamping load is applied between the end plates 34a and 34b. On the end plate 34 a side, a fuel gas inlet manifold 36 a for supplying fuel gas to the fuel gas passage 28 of each power generation cell 14, and an off-gas containing unused fuel gas that has passed through the fuel gas passage 28 are provided. A fuel gas outlet manifold 36 b for discharging, an oxidant gas inlet manifold 38 a for supplying an oxidant gas to the oxidant gas flow path 30, and an unused oxidant gas that has passed through the oxidant gas flow path 30. An oxidant gas outlet manifold 38b for discharging off-gas containing the gas, a temperature adjusting fluid inlet manifold 40a for supplying a temperature adjusting fluid to the temperature adjusting fluid channel 32, and the temperature adjusting fluid channel 32. A temperature adjustment fluid outlet manifold 40b for discharging the temperature adjustment fluid after the temperature adjustment is formed.

  In the first embodiment, the end plate 34a is provided with an inlet manifold and an outlet manifold for each fluid. For example, the end plate 34a is provided with an inlet manifold, while the end plate 34b is provided with an outlet manifold. Also good.

  The fuel cell stack 12 includes a fuel gas supply device 42 that communicates with the fuel gas inlet manifold 36a and the fuel gas outlet manifold 36b, and an oxidant gas supply device 44 that communicates with the oxidant gas inlet manifold 38a and the oxidant gas outlet manifold 38b. Are connected to the temperature adjusting fluid inlet manifold 40a and the temperature adjusting fluid outlet manifold 40b.

  The fuel gas supply device 42 includes a fuel tank (hydrogen tank) 48 that stores high-pressure hydrogen, and a regulator 52, a valve 54, and an ejector 56 are connected to a fuel gas pipe 50 having one end connected to the fuel tank 48. Is done. The fuel gas conduit 50 communicates with the fuel gas inlet manifold 36 a of the fuel cell stack 12, while the fuel gas circulation path 58 that connects one end to the fuel gas outlet manifold 36 b is connected to the ejector 56.

  The oxidant gas supply device 44 includes a compressor (or supercharger) 60 for compressing and supplying air. The compressor 60 and the oxidant gas inlet manifold 38a of the fuel cell stack 12 are connected to an oxidant gas pipe line. 62 communicates. A humidifier 64 can be connected to the oxidant gas pipe 62 via a valve 66.

  The temperature adjustment fluid circulation device 46 includes a combustor 68 for heating (heat exchange) the temperature adjustment fluid by combustion of fuel gas and air. The combustor 68 and the temperature adjustment fluid inlet manifold 40 a of the fuel cell stack 12 communicate with each other via a temperature adjustment fluid supply line 70, and a pump 72 is disposed in the temperature adjustment fluid supply line 70. The temperature adjustment fluid outlet manifold 40b and the combustor 68 of the fuel cell stack 12 communicate with each other through a temperature adjustment fluid discharge line 74, and the temperature adjustment fluid supply line 70 and the temperature adjustment fluid discharge line 74 communicate with each other. A circuit is constructed.

  A fuel supply line 76 is connected to the combustor 68 through a valve 54, and an exhaust air supply line 78 connected to the oxidant gas outlet manifold 38 b of the fuel cell stack 12 is connected. The combustor 68 is provided with a waste heat gas pipe 80 for discharging waste heat gas generated when the temperature control fluid is heated. The waste heat gas pipe 80 is connected to a discharge path via a valve 82. 84 and the first waste heat gas supply path 86.

  The first waste heat gas supply path 86 is connected to a cover member 88 that surrounds the fuel cell stack 12 and auxiliary devices, and is opened in the cover member 88. The cover member 88 is provided with a heat insulating material and accommodates auxiliary devices such as a regulator 52, valves 54 and 66, an ejector 56, a humidifier 64, a pump 72, and the like. An exhaust pipe line 90 is connected to the cover member 88.

  A second waste heat gas supply path 94 is connected to the first waste heat gas supply path 86 via a valve 92 (arranged as necessary). The second waste heat gas supply path 94 is connected to a power storage device (E / S) 96 such as a capacitor or a battery.

  In the vicinity of the fuel cell stack 12, a temperature sensor 98 is disposed in order to detect the surface temperature of components constituting the fuel cell system 10.

  The operation of the fuel cell system 10 configured as described above will be described below.

  First, when the fuel cell system 10 is normally operated, a fuel gas such as a hydrogen-containing gas is supplied from the fuel tank 48 constituting the fuel gas supply device 42 to the fuel gas conduit 50. The fuel gas is adjusted to a predetermined pressure via the regulator 52 and then supplied to the fuel gas inlet manifold 36 a of the fuel cell stack 12 through the ejector 56.

  The fuel gas is supplied to the fuel gas flow path 28 constituting each power generation cell 14, moves along the anode side electrode 24, and is then discharged from the fuel gas outlet manifold 36 b to the fuel gas circulation path 58. The discharged off gas is supplied again to the fuel gas inlet manifold 36 a via the ejector 56.

  On the other hand, air is supplied as an oxidant gas to the oxidant gas pipe 62 under the action of the compressor 60 constituting the oxidant gas supply device 44. This air is sent to the humidifier 64 as necessary, and then supplied from the oxidant gas inlet manifold 38a of the fuel cell stack 12 to the oxidant gas flow path 30 of each power generation cell 14. After moving along the cathode side electrode 26, the air is sent from the oxidant gas outlet manifold 38 b to the combustor 68 through the exhaust air supply line 78, and from the exhaust path 84 through the waste heat gas line 80. It is discharged outside.

  Therefore, in the electrolyte membrane / electrode structure 16 constituting each power generation cell 14, the fuel gas supplied to the anode side electrode 24 and the air supplied to the cathode side electrode 26 are electrochemically generated in the electrode catalyst layer. It is consumed by the reaction and power is generated.

  In the temperature adjusting fluid circulation device 46, the temperature adjusting fluid is supplied from the temperature adjusting fluid inlet manifold 40 a of the fuel cell stack 12 to the temperature adjusting fluid flow path 32 under the action of the pump 72. The temperature adjustment fluid is cooled (temperature adjustment) of the power generation cell 14, and then discharged from the temperature adjustment fluid outlet manifold 40b and circulated.

  Next, the low temperature start of the fuel cell system 10 will be described with reference to the flowchart shown in FIG.

  First, it is determined whether or not the fuel cell stack 12 is warming up (step S1). If it is determined that the fuel cell stack 12 is not warming up (NO in step S1), the process proceeds to step S2, and the system warming-up valve 82 is turned off. In this state, the normal operation is performed.

  On the other hand, if it is determined that the fuel cell stack 12 is warming up (YES in step S1), the process proceeds to step S3, and whether or not the temperature detected by the temperature sensor 98 is higher than the warming-up threshold value. To be judged. When it is determined that the detected temperature is equal to or lower than the warm-up threshold value (NO in step S3), the process proceeds to step S4, and the system warm-up valve 82 is turned on.

  Here, the fuel cell stack 12 is warming up. For this reason, as shown in FIG. 1, the combustion gas is supplied to the combustor 68 from the fuel gas supply device 42 and off-gas air is supplied from the exhaust air supply pipe 78 to perform combustion. The heating is done.

  Accordingly, a relatively high temperature waste heat gas is discharged from the combustor 68 to the waste heat gas pipe line 80, and this waste heat gas is supplied into the cover member 88 from the first waste heat gas supply path 86. The As a result, the piping including the auxiliary devices and the fuel gas pipe 50 can be directly warmed up, and the warming-up speed of the auxiliary devices and the piping can be improved at once.

  Moreover, the relatively high-temperature waste heat gas is sent to the power storage device 96 via the second waste heat gas supply path 94, and the power storage device 96 is directly warmed up. At that time, as shown in FIG. 3, the output of the power storage device 96 fluctuates with respect to the temperature, and the output at a low temperature is considerably reduced. Therefore, by directly warming up the power storage device 96 with waste heat gas, the output characteristics of the power storage device 96 are improved at once, and the power storage device 96 can exhibit desired performance in a short time. Become.

  Thereby, in 1st Embodiment, the effect that the low temperature starting characteristic of the fuel cell system 10 can be improved favorably with a simple and economical structure is acquired.

  Next, when the temperature of the fuel cell stack 12 exceeds the warm-up threshold value (YES in step S3), the process proceeds to step S5 and the valve 82 is turned off. Accordingly, the waste heat gas is discharged to the discharge path 84, the warm-up operation of the fuel cell system 10 is finished, and it is possible to shift to the normal operation.

  In the first embodiment, the exhaust air discharged to the oxidant gas outlet manifold 38b of the fuel cell stack 12 is supplied to the combustor 68. However, the present invention is not limited to this. For example, an oxidant gas supply pipe (not shown) may be branched from the oxidant gas pipe 62 and air may be directly supplied to the combustor 68.

  FIG. 4 is a schematic configuration explanatory diagram of a fuel cell system 100 according to the second embodiment of the present invention.

  The same components as those of the fuel cell system 10 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly, in the third embodiment described below, detailed description thereof is omitted.

  In the fuel cell system 100, a fuel gas supply device 102, an oxidant gas supply device 104, and a temperature control fluid circulation device 46 are connected to the fuel cell stack 12. The fuel gas supply device 102 may be configured in the same manner as the fuel gas supply device 42 described above, or may employ various configurations that are normally used. The oxidant gas supply device 104 may be similarly configured in the same manner as the oxidant gas supply device 44 described above, or may employ various configurations that are normally used.

  The power storage device 96 is provided with a cooling duct 106 for cooling the power storage device 96, and the second waste heat gas supply path 94 communicates with the cooling duct 106. That is, the cooling duct 106 constitutes at least a part of the second waste heat gas supply path 94.

  Therefore, in the second embodiment, the same effect as that of the first embodiment can be obtained, and the waste heat gas is supplied to the cooling duct 106 provided in the power storage device 96. There is an advantage that the machine configuration is effectively simplified.

  FIG. 5 is a schematic configuration explanatory diagram of a fuel cell system 120 according to the third embodiment of the present invention.

  In the fuel cell system 120, a discharge path 84, a first waste heat gas supply path 86, and a third waste heat gas supply path 124 can be connected to a waste heat gas pipe 80 connected to the combustor 68 via a valve 122. It is. The third waste heat gas supply path 124 is connected to the heat exchanger 126, and the heated air that exchanges heat with the waste heat gas supplied to the heat exchanger 126 passes through the pipe 128. To the vehicle compartment (not shown).

  Thereby, in 3rd Embodiment, the inside of a vehicle interior can be warmed using the waste heat gas discharged | emitted from the combustor 68, and the effect that the effective utilization of waste heat gas is achieved further is acquired.

1 is an explanatory diagram of a schematic configuration of a fuel cell system according to a first embodiment of the present invention. 4 is a flowchart for explaining a low-temperature start of the fuel cell system. It is explanatory drawing of the output characteristic with respect to the temperature of an electrical storage apparatus. It is a schematic structure explanatory drawing of the fuel cell system concerning the 2nd Embodiment of this invention. It is schematic structure explanatory drawing of the fuel cell system which concerns on the 3rd Embodiment of this invention. 1 is a configuration explanatory diagram of a polymer electrolyte fuel cell power generation system of Patent Document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 100, 120 ... Fuel cell system 12 ... Fuel cell stack 14 ... Power generation cell 16 ... Electrolyte membrane electrode assembly 18, 20 ... Metal separator 22 ... Solid polymer electrolyte membrane 24 ... Anode side electrode 26 ... Cathode side electrode 28 ... Fuel gas flow path 30 ... Oxidant gas flow path 32 ... Temperature adjustment fluid flow path 34a, 34b ... End plate 36a ... Fuel gas inlet manifold 36b ... Fuel gas outlet manifold 40a ... Temperature adjustment fluid inlet manifold 40b ... Temperature adjustment fluid outlet Manifold 42, 102 ... Fuel gas supply device 44, 104 ... Oxidant gas supply device 46 ... Temperature control fluid circulation device 48 ... Fuel tank 50 ... Fuel gas conduit 52 ... Regulator 54, 66, 82, 122 ... Valve 56 ... Ejector 58 ... Fuel gas circulation path 60 ... Compressor 62 ... Oxidant gas pipe line 64 Humidifier 68 ... Combustor 70 ... Temperature adjustment fluid supply line 74 ... Temperature adjustment fluid discharge line 76 ... Fuel supply line 78 ... Exhaust air supply line 80 ... Waste heat gas line 84 ... Discharge path 86, 94, 124 ... Waste heat gas supply path 88 ... Cover member 90 ... Exhaust pipe line 96 ... Power storage device 98 ... Temperature sensor 126 ... Heat exchanger 128 ... Pipe line

Claims (3)

An electrolyte / electrode structure provided with a pair of electrodes on both sides of an electrolyte is provided with a power generation cell sandwiched between separators, and is used to operate a fuel cell stack in which a plurality of the power generation cells are stacked, and the fuel cell stack A fuel cell system comprising auxiliary devices and a power storage device capable of storing and supplying electric energy,
A temperature adjusting fluid circulating device for circulating a temperature adjusting fluid in the fuel cell stack;
The temperature control fluid circulation device is configured to burn a reaction gas used for a power generation reaction of the power generation cell to heat the temperature control fluid;
A first waste heat gas supply passage for supplying waste heat gas discharged from the combustor when heating the temperature adjusting fluid to at least the auxiliary devices to warm up the auxiliary devices;
A second waste heat gas supply path for supplying the waste heat gas to the power storage device to warm up the power storage device;
A fuel cell system comprising:   2. The fuel cell system according to claim 1, wherein the second waste heat gas supply path is constituted by a cooling duct used for cooling the power storage device. 3. The fuel cell system according to claim 1, further comprising a heat exchanging unit configured to raise a temperature in a vehicle interior using the waste heat gas.

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