JPH11307112A - Solid polymer electrolyte type fuel cell power generation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an entire system into a compact size in order to use a solid polymer electrolyte type fuel cell as a power source of an automobile and enhance the load response. SOLUTION: A reformer 26 is so structured as to have the function of a shift converter by using a reforming catalyst having high low-temperature activity and making it operable at the same temperature as the operation temperature of a shift converter, so that the shift converter is omitted and the system is formed into a compact size. In addition, its load responsiveness is improved by using a heat medium 30 having a large heat capacity as compared with gas for heating the reformer 26. The compaction of the system is realized by composing a composite heat exchanger 33 by integrating a heating part 34 of the heat medium 30, a methanol evaporating part 35 and a steam generation part 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power generator for a solid polymer electrolyte fuel cell, among fuel cells used in the energy sector which directly converts chemical energy of fuel into electric energy.

[0002]

2. Description of the Related Art The use of fuel cells as power sources for automobiles, ships, spacecrafts, and the like has been studied.
Since power is generated at a low temperature of 00 ° C or less, the output density is high, and the device operates at a low temperature, it has advantages such as less deterioration of battery constituent materials and easy start-up. Is effective as a power source for transport vehicles.

[0003] The basic structure of a solid polymer electrolyte fuel cell is that both surfaces of a solid polymer electrolyte membrane are coated with both a porous cathode (oxygen electrode) and an anode (fuel electrode) using a noble metal such as platinum as a catalyst. A cell is formed by being sandwiched between diffusion electrodes to form a cell, the cells are stacked via a separator to form a stack, gas passages are formed on both front and back surfaces of each separator, and an oxidizing gas is supplied to the cathode side. The gas is supplied and discharged through the gas passage, and the fuel gas is supplied and discharged through the gas passage on the anode side. Further, since the reaction of the fuel cell is an exothermic reaction, one cooling unit is provided for every several cells. Is provided.

As a power generator using a solid polymer electrolyte fuel cell having such a configuration, there is a conventional system configuration as shown in FIG. That is, a cell in which both surfaces of the solid polymer electrolyte membrane 1 are sandwiched between the gas diffusion electrodes of the cathode 2 and the anode 3 is stacked with a separator interposed therebetween to form a stack, and one cooling unit 4 is provided for every several cells. A reformer 5, a heat exchanger 6, a shift converter 7, a CO
The remover 8 is installed in order from the upstream side to the downstream side, and methanol as a raw material supplied from the methanol tank 9 is
A methanol supply line 11 is provided so as to be introduced into the reformer 5 via a methanol evaporator 10, while a water tank 1 is provided.
A steam line 14 for sending a part of the water from 2 into steam by a steam generator 13 is connected to the methanol supply line 11 so that methanol and steam are introduced into the reformer 5 to perform steam reforming. At the same time, another part of the water is passed through the heat exchanger 6 and the CO remover 8 for cooling, and the fuel gas FG reformed in the reformer 5
Is cooled by the heat exchanger 6 with the cooling water from the water tank 12, and then the shift converter 7 is operated at 200 ° C.
To carry out a shift reaction in the solid polymer electrolyte fuel cell I
The concentration of carbon monoxide (CO), which is a catalyst poison, is reduced to a concentration (1% or less) that the CO remover 8 can process. The fuel gas FG that has been subjected to the CO removal treatment by the CO remover 8 operated at 150 ° C. is supplied to the anode 3 of the solid polymer electrolyte fuel cell I via the humidifier 15. On the other hand, the cathode 2 of the solid polymer electrolyte fuel cell I
At the inlet side, air A as an oxidizing gas is compressed by the compressor 17 of the turbocharger 16 and supplied through the humidifier 15, and a part of the air A is branched into the CO remover 8 and CO is removed. It is used for combustion, and
After the entire amount of the cathode exhaust gas CG discharged from the cathode 2 and a part of the anode exhaust gas AG discharged from the anode 3 are burned in a combustor 19, they are introduced into a combustion chamber of a reformer 5. Methanol in the reforming chamber of the reformer 5 is heated to 250 ° C. in the presence of the reforming catalyst to absorb heat and react to reform the fuel gas FG.

The exhaust gas discharged from the combustion chamber of the reformer 5 is combusted in a combustor 20 together with a part of the anode exhaust gas AG discharged from the anode 3 and then guided to a turbine 18 for the compressor 17. The exhaust gas discharged from the turbine 18 is driven through the steam generator 13 and the methanol evaporator 10 to be discharged as exhaust gas. Further, a part of the cooling water from the water tank 12 is allowed to pass through the cooling section 4 of the solid polymer electrolyte fuel cell I via the humidifier 15 and passed through the cooling section 4. The cooling water is supplied to the cooler 21
And cooled into the water tank 12, and a steam-water separator 23 in the cathode exhaust gas line 22.
The water separated by the steam separator 25 in the anode exhaust gas line 24 is returned to the water tank 12 together with the water passed through the heat exchanger 6 and the CO remover 8.

[0006]

However, when a fuel cell is used as a power source for a vehicle such as an automobile, the fuel cell power generator must be compact and load responsive. Type fuel cell power generator,
The anode exhaust gas AG discharged from the anode 3 is burned in the combustor 19 in order to obtain heat necessary for the endothermic reaction in the reformer 5, and the load fluctuates to reform in the reformer 5. Even if the amount of gas and the fuel utilization rate at the anode 3 fluctuate, this cannot be dealt with flexibly, and the reformer 5 reforms methanol as a raw material. A line for supplying the fuel gas FG to the anode 3 is provided with a heat exchanger 6, a shift converter 7, and a CO remover 8 for cooling the fuel gas. The unit 13 is also provided separately, and there is a limit to compactness. Further, since the polymer electrolyte fuel cell is poisoned by CO,
The CO concentration must be below 10-100 ppm. However, this CO concentration is greatly affected by the mixing ratio (S / C) of steam and methanol.
In the fuel cell power generator shown in FIG. 3, no consideration is given to keep the S / C constant.
There was a problem that C changed.

Therefore, the present invention provides a simple and compact system as a whole, improves the load response, and can be used as a power source for a vehicle such as an automobile. Is intended to provide a solid polymer electrolyte fuel cell power generator in which the constant is always constant.

[0008]

According to the present invention, in order to solve the above-mentioned problems, a solid polymer electrolyte membrane is sandwiched between a cathode and an anode, and an oxidizing gas is supplied to the cathode side.
A line for reforming and supplying methanol to the anode of the fuel cell, which supplies fuel gas to the anode side, is operated at the same temperature as the shift converter using a reforming catalyst having high low-temperature activity. And the reformer
A CO remover for removing carbon monoxide in the fuel gas reformed by the reformer is installed, and a methanol evaporator, a steam generator, and a heating medium heater are integrated upstream of the reformer. The heat exchanger used to heat the reformer is installed by introducing a combined heat exchanger into which the methanol evaporated in the methanol evaporator and the steam generated in the steam generator are introduced. The medium is configured to be heated by the heat medium heating unit of the composite heat exchanger and guided to the reformer.

A compact heat exchanger can be achieved by integrating the reformer and the shift converter, and the combined heat exchanger is formed by integrating the methanol evaporator, steam generator and heat medium heater. Therefore, the space required for installation on an automobile can be reduced, which is advantageous. Further, since a heat medium is used for heating the reformer, load responsiveness can be improved.

Further, the exhaust gas of the exhaust gas turbine is used for heating the heat medium, but by using an appropriate temperature range of the exhaust gas, overheating of the heat medium can be prevented, and the reforming catalyst of the reformer can be used. It will be possible to operate at a temperature below the allowable temperature limit.

By employing air cooling as the cooling means of the CO remover, the system can be made compact by eliminating a cooling line as compared with a system in which cooling water or cooling gas is passed.

Further, by mechanically synchronizing the respective metering pumps of methanol and water, the ratio of methanol and water always becomes a set value, and the concentration of carbon monoxide is maintained at 10 to 100 ppm even when a load is responded. It can be reduced to:

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In the configuration similar to that of the solid polymer electrolyte fuel cell power generation apparatus shown in FIG. 3, which performs steam reforming using methanol as a raw material, The reformer 5 and the shift converter 7 are integrated to reform methanol to reduce the number of devices in a line for supplying fuel gas to the anode 3 of the solid polymer electrolyte fuel cell I, thereby simplifying the fuel cell system. The equipment is also simplified to reduce the size of the entire system, and to obtain heat for causing an endothermic reaction in the reformer with a heat medium having a large heat capacity so as to enhance load responsiveness. The metering pump for methanol and water is mechanically synchronized so that the ratio between methanol and water is always constant, so that the rotation speed of the pump is constant.

More specifically, the reforming catalyst of the reformer and the low-temperature shift catalyst of the shift converter when methanol is used as a raw material are both catalysts containing copper (Cu) and zinc (Zn) as active components. Focusing on this, instead of the conventional reformer 5, a reforming catalyst having a high low-temperature activity is used as the catalyst, and the same operating temperature as the operating temperature of the shift converter 7 is used.
By providing the reformer 26 which can be operated at 0 ° C., the heat exchanger 6 and the shift converter 7 which are conventionally installed are eliminated, and as shown in FIG. Only the CO remover 27 operating at a temperature of 0 ° C. is installed in the line 28 for reforming and supplying methanol on the inlet side of the anode 3 of the solid polymer electrolyte fuel cell I, and the CO remover 27 By installing an air-cooled fin 29 as a cooling means, and cooling the CO remover 27 with the air-cooled fin 29 instead of cooling with cooling water or cooling gas shown in FIG.
The conventional cooling line is omitted to simplify the system.

A heating medium 30 having a larger heat capacity than gas is used for heating the reformer 26, and the heating medium 30 is circulated by a heating medium pump 32. A heating medium heating unit for heating the heating medium flowing through the heating medium circulation line;
With the methanol evaporator 10 and the steam generator 1 in FIG.
3 constitutes a composite heat exchanger 33 integrated in the middle of a methanol evaporating section 35 and a steam generating section 36. Methanol that has passed through the methanol evaporating section 35 of the composite heat exchanger 33 and a composite heat exchanger The steam that has passed through the steam generating section 33 is introduced into the reforming chamber of the reformer 26, and the heat medium 30 that is heated by the heating medium heating section 34 and flows through the heating chamber of the reformer 26. The reformer 26 is heated, and the turbocharger compressor 39 is used in place of the turbocharger 16 in FIG. The exhaust gas discharged from the exhaust gas turbine 38 of the compressor 37 is used for heating the composite heat exchanger 33,
The turbine exhaust gas line 40 is connected to the composite heat exchanger 33 so that the exhaust gas is used for evaporating water, heating a heat medium, and evaporating methanol, and a part of the exhaust gas is branched from the turbine exhaust gas line 40. It is connected to a starting combustor 42 via a branch line 41, and a portion of the methanol introduced into the starting combustor 42 is burned so that the methanol can be introduced into the composite heat exchanger 33 for heating at the time of starting. ,on the other hand,
The exhaust gas combusted by the catalytic combustor 43 is introduced into the exhaust gas turbine 38, and the entire amount of the cathode exhaust gas from the cathode 2 and the entire amount of the anode exhaust gas from the anode 3 are introduced into the catalytic combustor 43 for combustion. Let it do.

Further, a metering pump 44 for pressure-feeding methanol from the methanol tank 9 to the methanol evaporating section 35 of the composite heat exchanger 33, and a composite heat exchanger 33 from the water tank 12
And a metering pump 45 for pumping water to the steam generator 36 of
The connection is made by the connecting means 46 so as to be mechanically synchronized so that the ratio of the number of rotations is constant so that the ratio of methanol to water is always constant even when the load changes.

Other configurations are the same as those of the conventional system shown in FIG. 3, and the same components are denoted by the same reference numerals.

FIG. 2 shows a composite heat exchanger and a reformer and a CO
This is a specific example in which a remover and a heat medium circulation line are assembled. Reference numeral 47 denotes a heat medium tank, and the heat medium in the heat medium tank 47 is circulated by a heat medium pump 32 through a closed loop circulation line 31. It was made.

When the solid polymer electrolyte fuel cell power generator of the present invention is started, first, methanol in the methanol tank 9 is catalyzed by the starting combustor 42, and steam is generated by the combustion heat. The heating of the heating medium 30 and the evaporation of methanol are performed. The heated heat medium heats the reformer 26 by circulating and flowing through the heat medium circulation line 31, and the methanol that has passed through the methanol evaporator 35 and the steam generated by the steam generator 36 are discharged from the reformer 26. It is introduced into a reforming chamber, and steam reforming of methanol is performed.

The reformer 26 is operated at 200 ° C. which is the same as the operating temperature of the conventional shift converter, and the CO concentration at the outlet of the reformer 26 can be reduced to a concentration that can be processed by the CO remover 27. Fuel gas F reformed in reformer 26
G enters the CO remover 27, where CO accompanying the fuel gas is removed. Since the air-cooled fins 29 are used as the cooling means of the CO remover 27, it is not necessary to provide a cooling line in the CO remover 27 as in the case of the conventional cooling water, and the system can be simplified,
In addition, since the reformer 26 has a configuration in which the conventional reformer and the shift converter are integrated, the system can be more simplified and the size can be reduced.

The fuel gas FG from which CO has been removed by the CO remover 27 is supplied to the anode 3, and the anode exhaust gas AG discharged from the anode 3 is separated into steam and water by the steam-water separator 25, and the gas is used as a catalyst. The water is introduced into the combustor 43 and the water is introduced into the water tank 12.

On the other hand, to the cathode 2, the air A compressed by the rescholl compressor 39 is supplied as an oxidizing gas, and a part of the air is supplied to the CO remover 27.
Cathode exhaust gas CG discharged from the cathode 2 is separated into steam and water by a steam-water separator 23, and the entire amount of gas is exhausted by the catalytic combustor 4.
3 and the water is introduced into the water tank 12.

The exhaust gas burned and exhausted by the catalytic combustor 43 is sent to an exhaust gas turbine 38, where it is expanded and expanded, and the composite heat exchanger 33 and the starting combustor 42 are expanded.
The turbine exhaust gas sent to the combined heat exchanger 33 is subjected to steam generation, heating of a heat medium, and evaporation of methanol, and then discharged.

In the present invention, as described above, the heat medium 30 having a large heat capacity is used for heating the reformer 26. However, since the heat medium has a larger specific heat than the gas,
It is superior in response to load change compared to gas heating, and can improve load response. In addition, since the heat resistant temperature of the reforming catalyst of the reformer 26 is 350 ° C., the heating of the reformer 26 If the temperature of the heat medium 30 used for the heating is too high, the reforming catalyst is deteriorated. However, in the present invention, the exhaust gas discharged from the exhaust gas turbine 38 is used for heating the heat medium 30. Therefore, by using an appropriate temperature range of the exhaust gas, it is possible to prevent the heating medium temperature from being overheated when the heating medium is directly heated by the combustion gas.

[0026]

As described above, the solid polymer electrolyte fuel cell power generator according to the present invention has the above-described configuration, and therefore can provide the following excellent effects. (1) Since a reforming catalyst with high low-temperature activity is used for the reformer and the reformer is operated at the same low temperature as the operating temperature of the shift converter, the heat exchanger and shift The converter can be eliminated, and the system can be simplified and downsized. (2) Since cooling is performed by air-cooled fins without using cooling gas or cooling water as cooling means for the CO remover, a cooling line for flowing cooling fluid can be eliminated, and the system can be cooled. Can be simplified. (3) Since a heat medium with a large heat capacity is used for heating the reformer, the heat medium has a higher specific heat than gas, so it has better response to load changes compared to gas heating and can improve load response. it can. (4) The heating section for heating the heat medium is integrated with a steam generation section and a methanol evaporating section to form a composite heat exchanger, and the exhaust gas turbine is used for evaporating water, heating the heating medium, and evaporating methanol in the composite heat exchanger. The use of a composite heat exchanger reduces the number of separately used devices, simplifies the system, and heats the heating medium from the exhaust gas turbine. Since the exhaust gas is used, by using an appropriate temperature range of the exhaust gas, it is possible to operate the reformer at a temperature lower than the allowable temperature limit of the reforming catalyst, and to prevent overheating of the heat medium temperature. (5) Since the metering pump that sends methanol to the methanol evaporator and the metering pump that sends water to the steam generator are mechanically synchronized, the ratio between the rotation speeds of both the methanol and water metering pumps is kept constant. Thus, even when the load changes, the ratio of methanol to water can be kept constant, and the CO concentration can be reduced to 10 to 100 ppm or less. (6) As described above, the solid polymer electrolyte fuel cell power generator can have a compact system configuration and can achieve improved load responsiveness, which is optimal as a power source for an automobile.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a system configuration of a solid polymer electrolyte fuel cell power generator according to the present invention.

FIG. 2 is a perspective view showing an example in which a reformer, a CO remover, and a heat medium circulation line are combined with the composite heat exchanger in FIG.

FIG. 3 is a system configuration diagram of a conventional solid polymer electrolyte fuel cell power generator.

[Explanation of symbols]

 I Solid polymer electrolyte fuel cell 1 Solid polymer electrolyte membrane 2 Cathode 3 Anode 9 Methanol tank 12 Water tank 26 Reformer 27 CO remover 28 Line 29 Air-cooled fin 30 Heat medium 31 Heat medium circulation line 33 Composite heat exchanger 34 Heat medium heating section 35 Methanol evaporation section 36 Steam generation section 37 Turbo-Richorm compressor 38 Exhaust gas turbine 39 Ryshorm compressor 44, 45 Metering pump 46 Connecting means

Continued on the front page (72) Inventor Takenori Watanabe 3-1-1-15 Toyosu, Koto-ku, Tokyo Ishikawajima-Harima Heavy Industries Co., Ltd. Inside the Toji Technical Center (72) Inventor Yasuo Yamanaka 3-1-1, Toyosu, Koto-ku, Tokyo No. Ishikawajima Harima Heavy Industries, Ltd.

Claims (4)

[Claims] 1. A solid polymer electrolyte membrane sandwiched between a cathode and an anode, an oxidant gas is supplied to the cathode side,
A line for reforming and supplying methanol to the anode of the fuel cell, which supplies fuel gas to the anode side, is operated at the same temperature as the shift converter using a reforming catalyst having high low-temperature activity. And the reformer
A CO remover for removing carbon monoxide in the fuel gas reformed by the reformer is installed, and a methanol evaporator, a steam generator, and a heating medium heater are integrated upstream of the reformer. The heat exchanger used to heat the reformer is installed by introducing a combined heat exchanger into which the methanol evaporated in the methanol evaporator and the steam generated in the steam generator are introduced. A solid polymer electrolyte fuel cell power generator, wherein the medium is heated by a heating medium heating section of the composite heat exchanger and guided to a reformer. 2. The solid polymer electrolyte fuel cell power generator according to claim 1, wherein exhaust gas from an exhaust gas turbine is used for evaporating methanol, heating a heat medium, and evaporating water in the composite heat exchanger. 3. The solid polymer electrolyte fuel cell power generator according to claim 1, wherein the cooling means of the CO remover is air-cooled. 4. A fixed quantity pump for sending methanol to a methanol evaporator and a fixed quantity pump for sending water to a steam generator are mechanically synchronized so that the ratio of the rotation speeds of the two fixed quantity pumps is constant. 4. The solid polymer electrolyte fuel cell power generator according to 2 or 3.