JPH0963618A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system of which the efficiency of a reforming apparatus is improved, the structure is simplified, and apparatuses are miniaturized with excellent mobility. SOLUTION: In a fuel cell system 1, an evaporator 11 is heated by a heater 10 and hydrogen is produced by reforming a fuel by a reforming apparatus 3 which is so composed as to supply a fuel evaporated by the evaporator 11 to a catalyst layer 12. The obtained hydrogen is supplied to a fuel cell to generate electricity and a part of a reaction gas produced by the reform is taken out of the catalyst layer 12 and fed back to the heater 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell system that reforms a raw material to produce hydrogen and supplies the obtained hydrogen to a fuel cell to generate electricity.

[0002]

2. Description of the Related Art As a fuel cell system, for example, a reformer that heats an evaporator by a heater and supplies the vaporized raw material to the catalyst layer to reform the raw material to produce hydrogen. Then, the hydrogen obtained is supplied to a fuel cell to generate electricity.

[0003]

In this fuel cell system, the fuel utilization efficiency of the cells of the fuel cell is usually 20 to 90.
%. This is determined in consideration of the power generation efficiency of the fuel cell system or the cells of the fuel cell or the economical efficiency during operation. Therefore, the flow rate of the raw material processed by the reformer is
It is higher than the net flow rate consumed by the fuel cell.

During steady-state power generation, it is common to produce the reaction gas in excess of that consumed in the cells of the fuel cell and use it as fuel for the heater.

Further, the CO contained in the reaction gas poisons the catalyst of the cell of the fuel cell and deteriorates the performance of the cell. Therefore, the reformer is required to have a high conversion rate. Therefore, it was necessary to secure a sufficient amount of catalyst for the reaction. Therefore, the reformer had to process more than the flow rate required in the cell with a high conversion.

Further, in order to proceed the reaction, it is necessary to apply heat, but since the heat resistance level of the catalyst is low, heat is absorbed on the inlet side and heat is generated on the outlet side, so that the temperature distribution tends to be uneven. For this reason, the reformer becomes large and the structure becomes complicated. Therefore, for example, a fuel cell system mounted on an automobile has a problem that it is not suitable for small-sized mobile use.

Further, in the fuel cell, there is an excess of water from the start to the steady state, a water shortage in the steady state, and an excess of water from the end of power generation to the stop. For this reason, complicated water supply control according to each operation mode was required. Especially,
At the time of startup, the humidity around the ion exchange membrane changes greatly with the temperature rise of the fuel cell, and even if water is supplied from the outside, the fuel cell is still cold and water vapor enters the gas passage midway. It was condensed and the ion exchange membrane of the electrode substrate could not be sufficiently humidified. As described above, the difficulty in controlling the humidity has been a cause of deterioration in the performance of the cells of the fuel cell or insufficient cell performance at the initial stage of power generation.
In addition, a large amount of water was required, and the resulting adverse effects such as gas passage blockage occurred.

When used for transportation, the amount of water required for the cells of the fuel cell fluctuates drastically depending on the load level, cell temperature and the like. On the other hand, the amount of humidification cannot cope with the speed of change. Therefore, it is difficult to properly control the humidification amount.

Furthermore, if water is supplied at the maximum value of fluctuation so as not to cause insufficient humidification, water will become excessive, and the gas diffusion passages such as the pores of the carbon paper, which is the electrode base material, will be clogged with water. However, there was a problem that the performance of the machine deteriorated. Further, when water was supplied at an average value in consideration of water fluctuation, the excess and deficiency of the supply was repeated, and the cell performance could not be sufficiently obtained.

The present invention has been made in view of the above points, and the invention according to claim 1 improves the efficiency of the reformer, has a simple structure, can be downsized, and is excellent in mobility. The present invention is aimed at providing a fuel cell system. It is another object of the inventions of claims 2 and 3 to provide a fuel cell system capable of maintaining the performance of the cells of the fuel cell even under operating conditions such as starting and stopping.

[0011]

In order to solve the above-mentioned problems and to achieve the object, the invention according to claim 1 heats an evaporator by a heater, and a raw material vaporized by the evaporator is used as a catalyst layer. In a fuel cell system for producing hydrogen by reforming a raw material by a reforming device adapted to supply the hydrogen to the fuel cell and supplying the obtained hydrogen to a fuel cell to generate electricity, a part of the reaction gas by the reforming is produced. Is taken out from the catalyst layer and returned to the heater.

As described above, when a part of the reaction gas by reforming is taken out from the catalyst layer, the amount of treatment is reduced on the downstream side of the reaction gas taking-out portion, so that the space velocity is relatively decreased, which is advantageous for the reaction. become. In addition, since the exothermic level also decreases, the equilibrium shifts to the side where the reaction proceeds, and the reaction conversion rate improves. Further, since the heat generation level on the downstream side is lower on the upstream side than the reaction gas extraction part, it is possible to increase the amount of heating by the heater to effectively carry out the reaction, and to the inlet side of the catalyst layer. The heat can be concentrated, the amount of heat generated on the outlet side of the catalyst layer can be reduced and the temperature can be made uniform, the performance of the reformer can be improved, and the size of the reformer can be reduced, thereby reducing the size of the heater.

Further, when the reaction gas is directly supplied from the reaction gas outlet to the heater, energy for purification is unnecessary as compared with the case where the gas purified for the fuel cell is used as the raw material. , Efficient. Further, since the processing amount can be reduced even in the post-process of the reforming apparatus, it is possible to improve the conversion rate and downsize the device.

According to the second aspect of the present invention, the evaporator is heated by the heater, and the raw material vaporized by the evaporator is supplied to the catalyst layer to reform the raw material to produce hydrogen. In the fuel cell system that supplies the obtained hydrogen to the fuel cell to generate electric power, inside the cell stack of the fuel cell, water for absorption at the time of excess water and supply at the time of water shortage is provided outside the electrode base material. It is characterized in that a storage unit is provided, water is stored in the water storage unit at the time of stop, and water in the water storage unit is supplied at startup.

In this way, by supplying water from the water storage unit at startup, the water storage unit rises at approximately the same temperature as the cell at startup, so that water can be supplied from the outside. Compared to this, more accurate humidity control is possible. Also, when stopped,
Since water can be stored in the cell or in the vicinity of the cell, it is possible to keep the humidity of the electrode base material of the cell substantially saturated during storage.

Further, it is possible to easily control the water supply of the fuel cell, and it is possible to supply the water corresponding to the load fluctuation during the power generation. In addition, since the amount of water supply can be minimized to the minimum required by the cell, the amount of water used can be reduced, the pump power required for water supply can be reduced, the amount of heating can be reduced, and the vaporizer, heat exchanger, etc. The water tank can be made smaller and the water tank can be made smaller, resulting in higher efficiency, smaller size and lighter weight.

According to the third aspect of the present invention, the evaporator is heated by the heater, and the raw material vaporized by the evaporator is supplied to the catalyst layer to reform the raw material to produce hydrogen. In the fuel cell system that supplies the obtained hydrogen to the fuel cell to generate electricity, the water storage inside the cell stack of the fuel cell is performed outside the electrode base material to absorb excess water and supply water when insufficient. It is characterized in that a unit is provided, water is stored in the water storage unit at the time of startup, and the water in the water storage unit is supplied at a steady state.

As described above, by supplying the water in the normal-time water storage unit, condensed water and excess water can be secured at the time of start-up, so that the supply amount of humidifying water can be reduced. In addition, during startup, water that does not contribute to humidification is removed from the gas passage, so high performance can be maintained from the start of power generation.

Further, it is possible to easily control the water supply of the fuel cell, and it is possible to supply the water corresponding to the load fluctuation during the power generation. In addition, since the amount of water supply can be minimized to the minimum required by the cell, the amount of water used can be reduced, the pump power required for water supply can be reduced, the amount of heating can be reduced, and the vaporizer, heat exchanger, etc. The water tank can be made smaller and the water tank can be made smaller, resulting in higher efficiency, smaller size and lighter weight.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the fuel cell system of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a fuel cell system.

The fuel cell system 1 is provided in, for example, an electric vehicle, and there is a system that runs using electricity generated by the fuel cell as a drive source. This fuel cell system 1 is
It is composed of a methanol tank 2, a reformer 3, a shift converter 4, a selective oxidation reactor 5, a fuel cell 6, a moisture recovery heat exchanger 7, a water tank 8 and a controller 9. The controller 9 is connected to various devices such as valves, pumps, fans, and sensors. Each of the reformer 3, shift converter 4, selective oxidation reactor 5 and fuel cell 6 is equipped with a temperature sensor Tr, Tb, Ts, Tp, Tc. Controlled.

The reformer 3 includes a heater 10 and an evaporator 1.
1, a catalyst layer 12 and the like are provided. In the heater 10,
The burner pump 13 is driven by the temperature detection of the temperature sensor Tb to supply methanol from the methanol tank 2, and the burner fan 14 is driven to supply air,
These are burned to heat the evaporator 11. Evaporator 11
Is supplied with a mixture of methanol supplied from the methanol tank 2 by driving the methanol pump 15 and water supplied from the water tank 8 by driving the water pump 16. The evaporator 11 is heated by the heater 10 to vaporize the mixed fuel of methanol and water, and the fuel vaporized by the evaporator 11 is supplied to the catalyst layer 12.

The reformer 3 reforms the raw material to produce hydrogen, and the hydrogen obtained by detecting the temperature of the temperature sensor Tr is supplied to the fuel cell 6 through the shift converter 4 and the selective oxidation reactor 5. To do. A switching valve 17 is provided between the reformer 3 and the shift converter 4, and this switching valve 17
The hydrogen is returned to the heater 10 of the reformer 3 by the operation of. The shift converter 4 is cooled by the cooling air fan 18 by detecting the temperature of the temperature sensor Ts. Shift converter 4
The hydrogen supplied from the reactor is mixed with the air supplied by the driving of the reaction air pump 19 and supplied to the selective oxidation reactor 5. The selective oxidation reactor 5 is cooled by the cooling air fan 20 by detecting the temperature of the temperature sensor Tp. A switching valve 21 is provided between the selective oxidation reactor 5 and the fuel cell 6, and the operation of the switching valve 21 returns hydrogen to the heater 10 of the reformer 3.

Water is supplied from the water tank 8 to the fuel cell 6 by driving the cooling / humidifying pump 22, and the temperature sensor Tc is supplied.
By the temperature detection, the pressurized air pump 23 is driven to supply air from the moisture recovery heat exchanger 7, and the fuel cell 6 generates electric power from these water, air and hydrogen. The water used in the fuel cell 6 is heat-exchanged in the moisture recovery heat exchanger 7 to be returned to the water tank 8. The hydrogen used for power generation in the fuel cell 6 is returned to the heater 10 of the reformer 3.

In the fuel cell system 1, the evaporator 11 is heated by the heater 10, and the raw material vaporized by the evaporator 11 is supplied to the catalyst layer 12 by the reformer 3 to reform the raw material. The hydrogen is produced, and the obtained hydrogen is supplied to the fuel cell 6 through the shift converter 4 and the selective oxidation reactor 5 to generate electric power, and the reformer 3 catalyzes a part of the reaction gas by the fuel reforming. The layer 12 is taken out from the middle and returned to the heater 10 via the return system 30. The return system 30 includes a reaction gas extraction part 31 provided on the catalyst layer 12 side, a pipe 32 connecting the reaction gas extraction part 31 and the heater 10 side, and a valve 33 provided on the pipe 32. Then, by opening the valve 33, a part of the reaction gas by the fuel reforming is taken out from the catalyst layer 12 and returned to the heater 10. As the valve 33, an ON / OFF valve or a flow rate adjusting valve is used.

The reforming reaction in the reforming device 3 is shown as follows. _{CH 3 OH → 3H 2 + CO} - 21kcal ··· (1) CO + H 2 O → CO 2 + H 2 + 10kcal ··· (2) CH 3 OH + H 2 O → 3H 2 + CO 2 - 11kcal ··· ( 3) The endothermic reaction (1) is dominant on the inlet side of the catalyst layer 12 near the heater 10, while the exothermic reaction (2) is dominant on the outlet side of the catalyst layer 12, and as a whole Is an endothermic reaction (3).

If a part of the reaction gas is taken out from the middle of the catalyst layer 12, the amount of treatment is reduced on the downstream side of the reaction gas take-out portion 31, so that the space velocity is relatively decreased, which is advantageous for the reaction. Further, since the exothermic level according to the exothermic reaction (2) also decreases, the equilibrium shifts to the right side of the reaction. Therefore, the reaction conversion rate is improved.

Further, since the heat generation level on the downstream side is lower on the upstream side than the reaction gas extraction section 31, the heating amount by the heater 10 is increased to effectively carry out the reaction of the endothermic reaction (1). It is possible to wake up. Therefore, heat can be concentrated on the inlet side of the catalyst layer 12, the amount of heat generated on the outlet side of the catalyst layer 12 can be reduced, and the temperature can be made uniform. Can be downsized.

Further, when the reaction gas is directly supplied from the reaction gas extraction section 31 to the heater 10, energy for purification is unnecessary as compared with the case where the gas purified for the cell is used as fuel. It is efficient. Further, since the amount of treatment can be reduced even in the post-process of the reforming device 3, it is possible to improve the conversion rate and downsize the device.

In the mobile fuel cell system 1 provided in, for example, an electric vehicle, the catalyst of the catalyst layer 12 used in the reformer 3 is mainly a copper-based catalyst. The copper-based catalyst has a low heat resistance and is about 300 ° C., and if it exceeds this temperature, the catalyst is severely deteriorated.
Care is taken to keep the upper limit of the catalyst temperature.

Further, since the reaction of the endothermic reaction (1) mainly occurs on the upstream side of the catalyst layer 12, heat is positively applied to the upstream side and heat is gently applied to the downstream side to generate an exothermic reaction ( 2)
Progressing the reaction of the formula is effective for improving the reaction conversion rate. Therefore, the position of the reaction gas extraction part 31 is preferably located on the downstream side of the high temperature part where the heat of the heater 10 is likely to be directly applied.

A concrete embodiment of the reformer will be described with reference to FIGS. 2 and 3. 2 is a sectional view of the reformer, and FIG. 3 is a sectional view taken along line III-III of FIG.

In the figure, reference numeral 41 denotes a tubular housing of the reforming apparatus 3, and a heating chamber 42 provided in the lower portion of the housing 41 is provided with an evaporator 11 for vaporizing the raw material, which is formed of a spiral pipe.
Is provided. The evaporator 11 is configured by spirally winding a continuous pipe, and has an evaporation section 11a for vaporizing the raw material and an overheating section 11b for further superheating the vaporized raw material gas. . Evaporator 11
A burner 43 that constitutes the heater 10 is installed below. A fan 44 is connected to the heating chamber 42 so that air is forcibly blown.

Above the heating chamber 42, the catalyst layer 12 formed by spirally winding two parallel plate materials is provided. A spiral heating layer 45 is formed in parallel with and adjacent to the catalyst layer 12. A heating gas passage 46 that penetrates vertically is provided at the center of the scroll-shaped catalyst layer 12 and the heating layer 45, and connects the heating chamber 42 and the heating layer 45 at the bottom. In the heating layer 45, several bypasses 47 leading to the heating chamber 42 are provided in the middle of the heating layer 45, and the temperature distribution in the intermediate region is adjusted.
Further, the heating gas passage 46 is penetrated by the superheated portion 11b extending from the evaporation portion 11a of the evaporator 11, and a pipe 48 extending from the superheated portion 11b communicates with the catalyst layer 12.

In the reformer 3, the heating gas generated in the heating chamber 42 by heating the burner of the heater 10 enters the heating layer 45 through the heating gas passage 46 and spirals outward from the center of the heating layer 45. Catalyst layer 12 while being washed away
Is heated and finally exhausted from the exhaust port 49 on the outer periphery. On the other hand, a raw material, for example, a mixed liquid of methanol and water is supplied from the supply pipe 50 to the evaporation unit 11a of the evaporator 11, and is vaporized by heating the burner of the heater 10 to become a raw material gas. The raw material gas is supplied to the catalyst layer 12 through the superheater 11b and the pipe 48, and reacts by being heated by the heating layer 45 while flowing spirally outward from the central portion thereof, and hydrogen gas is mainly used. It becomes the reaction gas of. The reaction gas is supplied from the exhaust pipe 51 to the fuel cell side.

The reformer 3 has a long reaction path because the catalyst layer 12 has a spiral shape and is formed by a spiral continuous layer. Therefore, the reformer 3 has a small number of parts and can be simplified.

Further, in the catalyst layer 12, the reactions of the equations (1) and (2) occur, and as a result, the reaction gas as shown on the right side of the equation (3) is generated. (1),
Of the equations (2), the first equation (1) is an endothermic reaction, while the latter equation (2) is an exothermic reaction, and the equation (2) is a reverse direction (← direction) in a high temperature atmosphere. It tends to react easily. Therefore, the raw material gas of the catalyst layer 12 and the heating gas of the heating layer are made to flow in the same direction in parallel, so that the temperature is high in the initial stage of the reaction and low in the latter stage. The reaction is less likely to occur and an extremely efficient reaction is performed. Further, when the heating gas is made to flow from the central portion of the reforming device 3 to the outside as in the embodiment,
Since the temperature becomes lower toward the outer periphery, the loss of heat energy to the outside can be reduced.

The reformer 3 takes out a part of the reaction gas by the fuel reforming from the middle of the catalyst layer 12 and returns it to the return system 30.
It is configured to be returned to the heater 10 via. The return system 30 includes a reaction gas extraction unit 31 provided on the catalyst layer 12 side.
And a pipe 32 connecting the reaction gas extraction part 31 and the heater 10 side, and a valve 33 provided in the pipe 32. By opening the valve 33, a part of the reaction gas due to the fuel reforming is It is taken out from the catalyst layer 12 and returned to the heater 10.

Another embodiment of the reformer will be described with reference to FIGS. 4 and 5. In the reformer 3 of the embodiment shown in FIG. 4, a plurality of catalyst layers 12a and 12b are vertically connected in series, a raw material is supplied to the lower catalyst layer 12a, and a reaction gas is discharged from the upper catalyst layer 12b. It Catalyst layer 12 connected in series
A reaction gas extraction part 31 is provided between a and 12b, the reaction gas extraction part 31 and the heater 10 side are connected by a pipe 32, and the pipe 32 is provided with a valve 33. By opening the valve 33, a part of the reaction gas by the fuel reforming is taken out from the catalyst layer 12a and returned to the heater 10.

In the reformer of the embodiment shown in FIG. 5, a plurality of catalyst layers 12c and 12d are constituted by a double cylinder, and the inner cylinder catalyst layer 12c and the outer cylinder catalyst layer 12d are connected. A reaction gas extraction part 31 is provided between the catalyst layers 12c and 12d connected in series, the reaction gas extraction part 31 and the heater 10 side are connected by a pipe 32, and the pipe 32 is provided with a valve 33. ing. By opening the valve 33, a part of the reaction gas due to the fuel reforming is partially discharged from the catalyst layer 12c and the catalyst layer 1.
It is taken out from between 2d and returned to the heater 10.

6 and 7 show a concrete structure of the reformer shown in FIG. 5, FIG. 6 is a sectional view of the reformer, and FIG. 7 is FIG.
FIG. 7 is a sectional view taken along line VII-VII of FIG.

The reformer 3 is provided with an evaporator 11 for vaporizing a liquid raw material, and a heater 10 consisting of a burner installed below the evaporator 11. Concentric cylindrical catalyst layers 12c and 12d are arranged above the evaporator 11, inside the catalyst layers 12c thus arranged, between the catalyst layers 12c and 12d, and outside the catalyst layer 12d. Have heating layers 45a, 45b, 45c through which the heating gas passes.

The evaporator 11 is constructed by spirally winding a continuous pipe, and the evaporator 1 for vaporizing the raw material is used.
It has 1a and an overheating part 11b for further superheating the vaporized raw material gas. The evaporation section 11a has a disc-shaped spiral that directly faces the burner of the heater 10, and the heating section 11b has a cylindrical spiral-shaped pipe that is inserted into the heating layer 45a. In this way, the pipes are formed into a disk shape or a cylindrical shape and are arranged in a plane shape, and the heater 10 and the catalyst layers 12c, 1
The partition between 2d and the heating layers 45b and 45c is partitioned. When a raw material for reaction is supplied to the evaporator 11 from the supply pipe 50, it is heated from the outside by the heater 10, first vaporized in the evaporation section 11a, and then superheated in the superheating section 11b.

The heater 10 is adapted to burn the combustion fuel supplied from the fuel supply source by taking in air from the air port 51 as shown by an arrow. The heating gas generated by this combustion heats the evaporator 11 and then exits through the gap between the pipes arranged in a plane to form the heating layer 45 as indicated by an arrow.
a, 45b, 45c respectively, and the catalyst layers 12c,
Exhaust gas is discharged from the upper exhaust pipe 52 by performing heat exchange while flowing countercurrently with the reaction gas flowing down 12d.

The upper part of the catalyst layer 12c communicates with the upper part of the superheater 11b, and the reaction gas is supplied from the superheater 11b. The lower sides of the catalyst layers 12c and 12d are connected to each other by a communication chamber 53, and the upper side of the catalyst layer 12d is collected in a collecting chamber 54, and a discharge pipe 55 is provided in the collecting chamber 54 and further connected to the fuel cell main body. ing. Such a catalyst layer 12
The raw material gas vaporized in the evaporator 11 is supplied to the c and 12d as shown by the arrow, and by reacting there, it becomes a reaction gas mainly composed of hydrogen gas, and passes through the upper collecting chamber 54 and the outlet pipe 55 to the fuel cell main body. F will be supplied.

According to the reformer 3, since the evaporator 11 is composed of a spirally wound pipe, it is possible to secure a large heat exchange area while being compact.
The load response can be improved. Further, since the pipe has a large number of gaps, the heating gas can be introduced into the catalyst tanks 12c and 12d with a low pressure loss.

Further, in the reformer 3, the pipes constituting the evaporator 11 are arranged in a plane and the heater 10 and the catalyst layer 12 are arranged.
Since the pipes are partitioned from c and 12d, the pipes arranged in a line form a partition effect, and the heating gas of the heater 10 that reaches 1000 ° C. or more directly reaches the catalyst layers 12c and 12d. I try not to.

In this reformer 3, a plurality of catalyst layers 12 are provided.
c and 12d are double cylinders, and the catalyst layer 1 is an inner cylinder.
2c and the outer cylindrical catalyst layer 12d are connected via a communication chamber 53. This catalyst layer 12 connected in series
A reaction gas extraction part 31 is provided between c and 12d, the reaction gas extraction part 31 and the heater 10 side are connected by a pipe 32, and a valve 33 is provided in the pipe 32. By opening the valve 33, a part of the reaction gas due to the reforming is taken out from between the catalyst layers 12c and 12d and returned to the heater 10.

Next, a specific embodiment of the fuel cell will be described with reference to FIGS. 8 is a front view of the fuel cell, FIG. 9 is a sectional view taken along line IX-IX of FIG. 8, and FIG. 10 is FIG.
2 is a cross-sectional view taken along line XX and YY of FIG.

The fuel cell 6 has a cell stack 103 assembled by the assembly shaft 102. The cell stack 103 is configured by stacking a plurality of separators 104a, 104b and 104c as a set and assembling them. The gas blocking plate 1 is provided between the separators 104a and 104c.
04d is provided. A tunnel passage 115b is formed between the separator 104c and the gas blocking plate 104d. Between the separators 104a and 104b,
A cell 106 is provided. Electrode base material B of cell 106
Is composed of an ion exchange membrane 107, a positive catalyst electrode 108 and a negative catalyst electrode 109. Ion exchange membrane 10
7. The outer peripheral portion 107a of No. 7 has separators 104a and 104b.
The ion-exchange membrane 107 has a positive catalyst electrode 108 on one side and a negative catalyst electrode 1 on the other side.
09, and hydrogen and oxygen of the reaction gas are reacted by this cell 106 to generate water, and at that time, electricity is generated.

Outside the positive catalyst electrode 108 of the cell 106, a porous guide body 110 formed of a porous member is provided.
Are arranged in contact with each other, and a porous guide body 111 formed of a porous member is also arranged in contact with the outside of the negative catalyst electrode 109. It constitutes a water storage unit A for supplying water.

The porous guide members 110 and 111 are formed of a porous porous member, and grooves 110a and 111a are formed on one surface side at equal intervals. The porous guide body 110 contacts the positive catalyst electrode 108 on the side on which the groove 110a is formed, and the porous guide body 111 forms the groove 11a.
1a is arranged in a direction orthogonal to the groove 110a of the porous guide body 110. Porous guide body 110
Is provided with a reaction gas passage 112 that communicates between the groove 110a of the cathode and the positive catalyst electrode 108.
A reaction gas passage 113 is provided between the groove 111 a and the negative catalyst electrode 109.

In the cell stack 103, the cells 106 are arranged at an angle α, and a gasket 114 is provided between the separators 104b and 104c surrounding the cell 106. The gasket 114 seals the cells 106. An inlet 115 for hydrogen is provided on the upper left side of the cell stack 103, and an outlet 116 for hydrogen is provided on the lower right side.
The gaskets 117 and 118 are provided between the separators 104a and 104b so as to surround the inlet 115 and the outlet 116, and seal the inlet 115 and the outlet 116. At the entrance 115, the cell 1
The inlet passage 115a is formed in the stacking direction of 06, and four tunnel passages 115b pass from the inlet passage 115a below the gasket 114 and the distribution passage 11 of the cell 106.
5c, from the distribution passage 115c to the reaction gas passage 11
It communicates with 3. An outlet passage 116 a is formed in the outlet portion 116 in the stacking direction of the cells 106.
The four tunnel passages 116b communicated with 16a pass below the gasket 114, and the collective passage 11 of the cell 106
6 c, and the collecting passage 116 c is the reaction gas passage 113.
Is in communication with

An oxygen inlet 119 is provided on the upper right side of the cell stack 103, and an oxygen outlet 1 is provided on the lower left side.
20 are provided, and gaskets 121 and 122 are provided between the separators 104a and 104b so as to surround the inlet 119 and the outlet 120, and seal the inlet 119 and the outlet 120. An inlet passage 119a is formed in the inlet portion 119 in the stacking direction of the cells 106. From this inlet passage 119a, four tunnel passages 119b pass below the gasket 114 and the distribution passage 1 of the cell 106 is formed.
19c, from the distribution passage 119c to the reaction gas passage 1
It communicates with 12. An outlet passage 120a is formed in the outlet portion 120 in the stacking direction of the cells 106, and the four tunnel passages 120b communicating with the outlet passage 120a pass under the gasket 114 and the collecting passage 1 of the cell 106.
20 c, and the collecting passage 120 c is connected to the reaction gas passage 11
Communicates with 2.

Further, the water passage 1 is provided at the contact portion of the gas blocking plate 104d, which is the lower surface in FIG. 9, with the porous guide body 110.
23 is formed. One side 123a of the water passage 123
Is a tunnel passage 124 that passes below the gasket 114.
The discharge port 124 provided on the upper side in the vicinity of the hydrogen inlet 115 via a, while the other 123b moves downward near the hydrogen outlet 116 via the tunnel passage 125a passing below the gasket 114. Provided supply section 125
Is communicated to. Gaskets 126a and 127a are provided between the separators 104a and 104c so as to surround the discharge section 124 and the supply section 125, respectively.
And the supply part 125 is sealed.

A water passage 128 is formed at the contact portion of the separator 104b, which is the upper surface in FIG. 9, with the porous guide body 110. One of the water passages 128a
Is a tunnel passage 129a passing under the gasket 114
Via the gas inlet 119 to the outlet 129 provided on the right side, and the other 128b is the gasket 1
It is communicated with a supply unit 130 provided on the left side in the vicinity of the oxygen outlet unit 120 via a tunnel passage 130 a passing below 14. Gaskets 126b and 127b are provided between the separators 104a and 104b so as to surround the discharge section 129 and the supply section 130, and seal the discharge section 129 and the supply section 130.

Therefore, when heated and humidified hydrogen is supplied from the hydrogen inlet portion 115 of the cell stack 103, the hydrogen containing water is supplied from the inlet passage 115a to the tunnel passage 11a.
5b to the distribution passage 115c of the cell 106,
The reaction gas passage 113 flows from the distribution passage 115c. On the other hand, when heated and humidified oxygen is supplied from the oxygen inlet 119, the oxygen containing water passes from the inlet passage 119a through the tunnel passage 119b to the distribution passage 11 of the cell 106.
9c, from the distribution passage 119c to the reaction gas passage 11
Flow through 2.

At this time, electric power is generated by the cell 106 to generate water by an electrochemical reaction of hydrogen and oxygen of the reaction gas and to take out the change in free energy at that time as electric energy. The cell 106 is a separator 104c
The cell 106 is connected in series with the adjacent cell 106 via the, and the generated electric power is taken out from a current collector (not shown) provided at both ends of the cell stack 103.

Hydrogen and water are mainly collected in the collecting passage 116c of the cell 106, are guided to the outlet passage 116a through the tunnel passage 116b, and are discharged from the outlet portion 116. Mainly oxygen and water are gathering passages 120c of the cell 106.
Collected at the exit passage 1 through the tunnel passage 120b
20a and is discharged from the outlet 120.

On the other hand, the electrochemical reaction of hydrogen and oxygen by the cell 106 is such that oxygen and water react with each other in the porous guide body 11.
0, the positive catalyst electrode 108 is supplied to the surface of the ion exchange membrane 107, and on the other hand, hydrogen and water pass through the porous guide body 111 and the negative catalyst electrode 109, and the ion exchange membrane 10
7 is supplied to the surface of the positive electrode 7 and the interface between the positive catalyst electrode 108 and the ion exchange membrane 107 and the interface between the negative catalyst electrode 109 and the ion exchange membrane 107. The ion exchange membrane 107 is
Since the elongation greatly changes depending on the water content, the ion exchange membrane 1 should always be kept at a proper humidification level.
It is necessary to keep the elongation of 07 constant and keep the interface stable.

Electricity is generated by the electrochemical reaction of hydrogen and oxygen of the reaction gas by this cell 106, and water is generated at that time, but not only the expansion due to the relative humidity inside this cell 106 When excess water such as generated condensed water, generated water, and excess supply water directly contacts the ion exchange membrane 107, the water further expands and the performance of the cell 106 deteriorates. However, a porous guide is provided to the catalyst electrodes 108 and 109 on both sides of the cell 106. The cells 110 and 111 are arranged in contact with each other, and the cell 1
The porous guide bodies 110 and 111 can absorb and remove excess water such as condensed water, generated water, and excess supply water that are generated in the inside of 06.

Therefore, the expansion of the ion exchange membrane 107 can be prevented, the performance of the cell 106 can be maintained at high efficiency for a long period of time, and the diffusibility of the reaction gas can be prevented from decreasing. Thus, excess water can be removed without using a special device, and the device can be simple, low-priced, compact and lightweight. Porous guide body 110, 111
By forming the reaction gas passages 112 and 113 by
When water is supplied, it is absorbed by the porous guide bodies 110 and 111, part of which diffuses into the reaction gas passages 112 and 113, and part of which moves directly to the catalyst electrodes 108 and 109, thereby effectively humidifying, When excess water is generated, it has a damper effect of absorbing it and supplying it when there is a shortage, and an appropriate amount of humidification is possible.

In addition, inside the cell stack 103 of the fuel cell 6, outside the electrode base material composed of the ion exchange membrane 107, the positive catalyst electrode 108 and the negative catalyst electrode 109, when water is absorbed and water is insufficient, Storage unit A for supplying water
Is provided, water is stored in the water storage unit A at the time of stop, and the water in the water storage unit A at the time of start is supplied.

In this way, by supplying water from the water storage unit A at startup, the water storage unit A rises at approximately the same temperature as the cell 106 at startup. Compared to this, more accurate humidity control is possible. Also, when stopped,
Since water can be stored in the water storage unit A while being contained in or near the cell 106, the humidity of the ion exchange membrane 107 of the cell 106 can be kept substantially saturated even during storage.

Further, the water supply control of the fuel cell 6 is easy, and the water supply corresponding to the load fluctuation can be performed at the time of power generation. Further, since the amount of water supplied can be set to the minimum necessary for the cell 106, the amount of water used can be reduced, the pump power required for supplying water can be reduced, the amount of heating can be reduced, the vaporization unit,
It is possible to reduce the size of heat exchangers and the water tank, and to achieve high efficiency and small size and weight.

Further, the water is stored in the starting-time water storage section A, and the steady-state water storage section A is supplied with the water. In this way, by supplying the water in the water storage unit A during steady state, it is possible to secure condensed water and excess water at the time of startup,
The supply amount of humidifying water can be reduced. In addition, during startup, water that does not contribute to humidification is removed from the gas passage, so high performance can be maintained from the start of power generation.

Further, the water supply of the fuel cell 6 can be easily controlled, and the water can be supplied in response to load fluctuations during power generation. In addition, since the amount of water supply can be minimized to the minimum required by the cell, the amount of water used can be reduced, the pump power required for water supply can be reduced, the amount of heating can be reduced, and the vaporizer, heat exchanger, etc. The water tank can be made smaller and the water tank can be made smaller, resulting in higher efficiency, smaller size and lighter weight.

11 to 14 show another embodiment of the water storage unit. The water storage unit A in FIG. 11 has a multi-layer structure, the first storage unit A1 is formed of a porous member having a passage 300, and the second storage unit A2 is also formed of a porous member. Water is the passage 300 of the first storage unit A1.
Is absorbed and held in the second storage unit A2 from the above, but the first storage unit A1 absorbs water better than the second storage unit A2, and the water storage amount is increased by making the water storage unit A a multi-layer structure. .

The water storage unit A shown in FIG. 12 also has a multi-layer structure. The first storage unit A1 is also formed of a porous member having a passage 300, and the second storage unit A2 is a porous member or an impermeable material. Has been formed. First of the second storage unit A2
The storage section A1 has a recess, and a space is formed between the recess and the first storage section A1.
Is formed. The water is absorbed and held in the second storage unit A2 from the passage 300 of the first storage unit A1, and a large amount of water is reliably held by the passage 301.

The water storage unit A in FIG. 13 also has a multi-layer structure, the first storage unit A1 is formed of a porous member having the passage 300, and the second storage unit A2 is also formed of a porous member. However, the impermeable material C is arranged outside the second storage portion A2. The first storage unit A1 has a passage 300
A guide passage 302 that connects the outside of the electrode base material B and the second storage portion A2 is formed between the two. A water passage 303 is formed between the second storage unit A2 and the impermeable material C. Therefore, by pulling with a negative pressure, water is absorbed in the first storage section A1 from the passage 300 and further absorbed in the second storage section A2 by the guide passage 302, so that the water is absorbed faster.

The water storage unit A of FIG. 14 also has a multi-layer structure, the first storage unit A1 is formed of a porous member having a passage 300, and the impermeable material C is provided outside the first storage unit A1.
Is arranged. A water passage 304 is formed between the impermeable material C and the first storage unit A1, and water is smoothly supplied from the water passage 304 to the first storage unit A1.

15 and 16 show the arrangement position of the water storage unit A. In the embodiment of FIG. 15, gas passages 400 are formed on both sides of the cell 106 made of an electrode base material, and a water storage portion A is formed in the space of the gas passages 400. As described above, the water storage unit A is the cell 1 having the electrode base material.
The water provided by the water pump 401 is stored in the water storage unit A at a position apart from 06.

In the embodiment shown in FIG. 16, a hydrogen inlet 115 and a hydrogen outlet 116 are provided on both sides of the cell 106 composed of an electrode base material. An inlet passage 115a is formed in the inlet portion 115 in the stacking direction of the cells 106, and four tunnel passages 115b are connected from the inlet passage 115a to the distribution passages 115c of the cell 106, and the water storage portion A is provided on the inlet side. It is formed.

An outlet passage 116a is formed in the outlet portion 116 in the stacking direction of the cells 106.
Four tunnel passages 116b from 16a communicate with the collecting passage 116c of the cell 106, and the water storage unit A is provided on the outlet side.
Is formed.

Next, the operation of the fuel cell system will be described with reference to FIG. In FIG. 17A, the characteristic curve a1 indicates the conventional operation, the characteristic curve b1 indicates the invention described in claim 1, and the characteristic curve c1 indicates the invention described in claim 2. Further, in FIG. 17B, the characteristic curve a2 indicates the conventional operation, the characteristic curve b2 indicates the invention described in claim 1, and the characteristic curve c2 indicates the invention described in claim 2.

In the conventional system, when the fuel cell system is stopped, the supply of water vapor to the fuel cell is gradually stopped immediately after the stop operation of the fuel cell system. During storage, the humidity inside the cell changes depending on the ambient temperature. As the temperature decreases, the humidity gradually approaches the saturated humidity, and when it exceeds the saturated humidity, water condenses and blocks passages and the like. Further, even if the temperature rises, since the condensed water is unevenly distributed, the effect of humidifying the membrane of the electrode base material is small.
At the time of start-up, preparation for supplying water (or steam) from the outside (driving a pump to generate steam by heating or heat exchange) is performed before power generation is started. With the start of power generation, the temperature of the cell is raised to an appropriate temperature and water (or steam) is supplied from the outside. During power generation, it is necessary to change the amount of water supplied according to the output, the temperature of the cell, and the like, so there is a problem in that the amount of humidification must be changed frequently.

The fuel cell system 1 according to the invention of claim 1
Then, at the time of stoppage, the supply of water vapor is not stopped, and the flow rate equal to or higher than that at the time of power generation is continued to be supplied to the water storage unit A as water. During storage, the saturated humidity is maintained according to the ambient temperature, and the condensed content is further absorbed. At the time of startup, the cell 106
Raise the temperature of to the proper temperature. External heating or self-heating is used for this. Water (or steam) is not supplied from the outside in the initial stage, but the water in the water storage unit A is used. The temperature of the water in the water storage unit A rises as the cell temperature rises and evaporates into the gas passage. This keeps the gas passages close to saturated humidity. Since there is a time limit only by humidifying the stored water by natural evaporation, water (or steam) is supplied from the outside after a certain period of time in order to shorten the startup time. Absorption of water during power generation
Since the release effect can be used, proper humidification control is possible without frequently changing the humidification amount.

Further, in the fuel cell system 1 according to the second aspect of the present invention, at the time of stop, the supply of steam is gradually stopped immediately after the stop operation of the system. During storage,
Maintained at saturated humidity due to ambient temperature. The condensed matter is further absorbed. At start-up, before power generation starts,
Preparations for supplying water (or steam) from the outside (driving a pump to generate steam by heating or heat exchange) are performed. With the start of power generation, the temperature of the cell is raised to an appropriate temperature and water (or steam) is supplied from the outside. Since the water in the water storage unit A can be used to some extent, water (or steam) is not supplied from the outside in the initial stage, and the water in the water storage unit A is used. Therefore, the water supply amount can be smaller than the conventional one. While supplying water, store the water in the water storage unit A and use it for humidity control later. During power generation, the effect of absorbing and releasing water can be used,
Proper humidification control is possible without changing the humidification amount frequently.

FIG. 18 is a block diagram showing another embodiment of the fuel cell system. The fuel cell 6 of this embodiment has the same structure as that of FIG. 1, but differs from that of FIG.
The air is sent from the water tank 8 to the heating unit 501 arranged in the reformer 3 by the driving of, and the air heated by the heating unit 501 is sent to the inlet side 502 of the fuel cell 6. Further, the reforming device 3 is driven by driving the water humidification pump 510.
Sends water from the water tank 8 to the heating unit 511 arranged in
The water heated by the heating unit 511 is configured to be sent to the inlet side 512 of the fuel cell 6.

In the fuel cell 6, the hydrogen side has a large amount of water at the inlet and the air side has a large amount of water at the outlet. Therefore, the reformer 3 is driven by driving the air pump 500 at a predetermined timing.
To the inlet side 502 of the fuel cell 6 by sending the air heated by the heating unit 501. Further, by driving the humidifying pump 510 for hydrogen at a predetermined timing, hydrogen is sent from the water tank 8 to the heating unit 511 arranged in the reformer 3, and the hydrogen heated by the heating unit 511 is supplied to the inlet side of the fuel cell 6. Send to 512.

As described above, the replacement can be carried out by driving the air pump 500 and the water humidification pump 510, whereby the water content can be kept uniform, and the replacement timing is
After a certain amount of electric current and a certain amount of electric power,
Every time the load becomes 0 (or below a certain value), or start /
Do it every time you stop. This air replacement is performed by the valve 50.
3, 504 is operated, and replacement of hydrogen is performed by operating valves 513, 514.

[0083]

As described above, according to the invention of claim 1, a part of the reaction gas by reforming is taken out from the catalyst layer,
It is configured to return to the heater, and part of the reaction gas by reforming is taken out from the catalyst layer.Therefore, the amount of treatment is reduced on the downstream side of the reaction gas extraction part, so the space velocity is relatively reduced, which is advantageous for the reaction. And the fever level will drop,
The equilibrium shifts to the side where the reaction proceeds, and the reaction conversion rate improves. Further, since the heat generation level on the downstream side is lower on the upstream side than the reaction gas extraction part, it is possible to increase the amount of heating by the heater to effectively carry out the reaction, and to the inlet side of the catalyst layer. The heat can be concentrated, the amount of heat generated on the outlet side of the catalyst layer can be reduced and the temperature can be made uniform, the performance of the reformer can be improved, and the size of the reformer can be reduced, thereby reducing the size of the heater.

Furthermore, since the reaction gas is supplied directly from the reaction gas extraction section to the heater, energy for purification is unnecessary and efficiency is improved as compared with the case where the gas purified for the cells of the fuel cell is used as fuel. good. Further, since the processing amount can be reduced even in the post-process of the reforming apparatus, it is possible to improve the conversion rate and downsize the device.

According to a second aspect of the present invention, a water storage unit for absorbing excess water and supplying water when water is insufficient is provided outside the electrode substrate inside the cell stack of the fuel cell. Since water is stored and the water in the water storage section is supplied at startup, and the water in the water storage section is supplied at startup, the temperature of the water storage section is almost the same as that of the cell at startup. Since the temperature rises at a higher temperature, it is possible to control humidity more accurately than when water is supplied from the outside. In addition, since water can be stored in the cell or in the vicinity of the cell when stopped, it is possible to keep the humidity of the ion exchange membrane of the cell substantially saturated even during storage.

Further, it is possible to easily control the water supply of the fuel cell, and it is possible to supply the water corresponding to the load fluctuation during the power generation. In addition, since the amount of water supply can be minimized to the minimum required by the cell, the amount of water used can be reduced, the pump power required for water supply can be reduced, the amount of heating can be reduced, and the vaporizer, heat exchanger, etc. The water tank can be made smaller and the water tank can be made smaller, resulting in higher efficiency, smaller size and lighter weight.

According to a third aspect of the present invention, a water storage unit for absorbing excess water and supplying water when water is insufficient is provided outside the electrode base material inside the cell stack of the fuel cell. Since water is stored and the water in the water storage section is supplied at steady time, and the water in the water storage section at steady time is supplied, condensed water and excess water can be secured at startup. The amount of humidifying water supplied can be reduced. In addition, during startup, water that does not contribute to humidification is removed from the gas passage, so high performance can be maintained from the start of power generation.

Further, it is possible to easily control the water supply of the fuel cell, and it is possible to supply the water corresponding to the load fluctuation during the power generation. In addition, since the amount of water supply can be minimized to the minimum required by the cell, the amount of water used can be reduced, the pump power required for water supply can be reduced, the amount of heating can be reduced, and the vaporizer, heat exchanger, etc. The water tank can be made smaller and the water tank can be made smaller, resulting in higher efficiency, smaller size and lighter weight.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a fuel cell system.

FIG. 2 is a cross-sectional view of a reformer.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a configuration diagram showing another embodiment of the reformer.

FIG. 5 is a configuration diagram showing still another embodiment of the reformer.

FIG. 6 is a cross-sectional view of a reformer.

FIG. 7 is a sectional view taken along the line VII-VII of FIG. 6;

FIG. 8 is a front view of a fuel cell.

FIG. 9 is a sectional view taken along the line IX-IX of FIG.

10 is a cross-sectional view taken along line XX and YY of FIG.

FIG. 11 is a diagram showing another embodiment of the water storage unit.

FIG. 12 is a view showing another embodiment of the water storage unit.

FIG. 13 is a diagram showing another embodiment of the water storage unit.

FIG. 14 is a diagram showing another embodiment of the water storage unit.

FIG. 15 is a diagram showing another embodiment showing the arrangement of the water storage unit.

FIG. 16 is a diagram showing another embodiment showing the arrangement of the water storage unit.

FIG. 17 is a diagram for explaining the operation of the fuel cell system.

FIG. 18 is a configuration diagram showing another embodiment of the fuel cell system.

[Explanation of symbols]

 1 Fuel Cell System 10 Heater 11 Evaporator 12 Catalyst Layer

Claims (3)

[Claims] 1. A hydrogen obtained by reforming a raw material by a reformer configured to heat the evaporator by a heater and supply the raw material vaporized by the vaporizer to a catalyst layer. In a fuel cell system for supplying power to a fuel cell to generate electric power, wherein a part of the reaction gas by the reforming is taken out from the catalyst layer and returned to the heater. 2. The hydrogen obtained by reforming the raw material by a reformer configured to heat the evaporator by a heater and supply the raw material vaporized by the vaporizer to the catalyst layer. In a fuel cell system that supplies electricity to a fuel cell to generate electricity, a water storage unit is provided inside the cell stack of the fuel cell outside the electrode base material for absorbing excess water and supplying water when insufficient. When storing water in the water storage section,
A fuel cell system configured to supply water from the water storage unit at startup. 3. The obtained hydrogen is produced by reforming the raw material by a reforming device configured to heat the vaporizer by a heater and supply the vaporized raw material to the catalyst layer. In a fuel cell system that supplies electricity to a fuel cell to generate electricity, a water storage unit is provided inside the cell stack of the fuel cell outside the electrode base material for absorbing excess water and supplying water when insufficient. A fuel cell system characterized in that water is stored in the water storage unit, and the water in the water storage unit is supplied in a steady state.