JP2014207115A - Secondary battery type fuel battery system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery type fuel battery system capable of stable power generation and charging.SOLUTION: A secondary battery type fuel battery system includes: a hydrogen generation part capable of releasing hydrogen by oxidation reaction and regeneration by reductive reaction; a power generation/electrolysis part having a power generation function for generating power by using hydrogen supplied from the hydrogen generation part and an electrolysis function for performing electrolysis with the steam supplied from the hydrogen generation part at the time of regeneration at the hydrogen generation part; a gas passage for circulating gas containing hydrogen and steam between the hydrogen generation part and the power generation/electrolysis part; and a water refilling part for refilling water to the gas passage. The water refilling part refills water except during power generation operation time of a system in which the power generation/electrolysis part is generating power and a charging operation time of a system in which the power generation/electrolysis part performs electrolysis.

Description

  The present invention relates to a secondary battery type fuel cell system capable of performing not only a power generation operation but also a charging operation.

  A fuel cell typically includes a solid polymer electrolyte membrane using a solid polymer ion exchange membrane, a solid oxide electrolyte membrane using yttria-stabilized zirconia (YSZ), a fuel electrode (anode) and an oxidizer electrode. The one sandwiched from both sides by the (cathode) has a single cell configuration. A fuel gas channel for supplying a fuel gas (for example, hydrogen) to the fuel electrode and an oxidant gas channel for supplying an oxidant gas (for example, oxygen or air) to the oxidant electrode are provided. Electric power is generated by supplying the fuel gas and the oxidant gas to the fuel electrode and the oxidant electrode, respectively.

  Fuel cells are not only energy-saving because of the high efficiency of the power energy that can be extracted in principle, but they are also a power generation system that excels in the environment, and are expected as a trump card for solving global energy and environmental problems.

Japanese National Patent Publication No. 11-501448 International Publication No. 2012/098945

  Patent Document 1 and Patent Document 2 disclose a secondary battery type fuel cell system that combines a solid oxide fuel cell and a hydrogen generating member that generates hydrogen by an oxidation reaction and can be regenerated by a reduction reaction. Yes. In the secondary battery type fuel cell system, the hydrogen generating member generates hydrogen during the power generation operation of the system, and the hydrogen generating member is regenerated during the charging operation of the system.

  The secondary battery type fuel cell system disclosed in Patent Document 1 is a system in which the space where the fuel electrode of the fuel cell unit and the hydrogen generating member are sealed is not a closed space, and always requires replenishment of water. It is.

  On the other hand, in the secondary battery type fuel cell system disclosed in Patent Document 2, the space where the fuel electrode of the fuel cell portion and the hydrogen generating member are sealed is a closed space, Since the power generation operation of the system and the charging operation of the system are performed using the existing mixed gas of hydrogen and water vapor, the system basically does not require replenishment of water.

  However, since the closed space is formed by the enclosure of a plurality of members, gas may escape from the joints between the members even though only a minute amount. In particular, hydrogen is easy to escape due to its low molecular weight. If the gas escapes from the closed space and decreases over a long period of time and the pressure in the closed space falls below a predetermined value, the gas is insufficient and the power generation performance and the charging performance are degraded. Further, when the hydrogen generating member is deteriorated due to sintering or the like after long-term use, the power generation performance and the charging performance are deteriorated.

  Therefore, the secondary battery type fuel cell system disclosed in Patent Document 2 replenishes the closed space with water when detecting a pressure drop in the closed space, a deterioration of the hydrogen generating member, etc. This prevents a decrease in charging performance.

  However, when water is replenished in the closed space, the water vapor concentration in the closed space temporarily increases and the hydrogen concentration decreases, which may temporarily cause power generation and charging to become unstable.

  In view of the above situation, an object of the present invention is to provide a secondary battery type fuel cell system capable of stable power generation and charging.

  In order to achieve the above object, a secondary battery type fuel cell system according to the present invention can release hydrogen by an oxidation reaction and can be regenerated by a reduction reaction, and is supplied from the hydrogen generation unit. A power generation / electrolysis unit having a power generation function for generating power using hydrogen and an electrolysis function for electrolyzing water vapor supplied from the hydrogen generation unit during regeneration of the hydrogen generation unit, the hydrogen generation unit, and the power generation / A secondary battery type fuel cell system comprising a gas flow path for circulating a gas containing hydrogen and water vapor between the electrolysis section and a water replenishment section for replenishing the gas flow path with water. The water replenishing unit has a configuration (first configuration) in which water is replenished except when the power generation / electrolysis unit is generating power and when the power generation / electrolysis unit is performing electrolysis. The power generation / electrolysis unit electrolyzes, for example, a power generation operation that generates power using hydrogen supplied from the hydrogen generation unit and water vapor supplied from the hydrogen generation unit during regeneration of the hydrogen generation unit. For example, the fuel cell may be configured to switch between the electrolysis operation and the fuel cell that generates power using hydrogen supplied from the hydrogen generation unit, and the hydrogen at the time of regeneration of the hydrogen generation unit. The structure separately provided with the electrolyzer which electrolyzes the water vapor | steam supplied from a generation | occurrence | production part may be sufficient.

  The secondary battery type fuel cell system of the first configuration further includes a temperature control unit that controls the temperature of the gas flow path, and the temperature control unit supplies water by the water supply unit replenishing water It is sometimes preferable to adopt a configuration (second configuration) for controlling the temperature of the gas flow path.

  In the secondary battery type fuel cell system having the first or second configuration, the fuel cell system further includes a flow rate control unit that controls a flow rate of a gas containing hydrogen and water vapor present in the gas flow path, and the flow rate control unit includes: It is preferable to adopt a configuration (third configuration) for controlling the flow rate of the gas containing hydrogen and water vapor existing in the gas flow path when the water replenishment unit performs water replenishment.

  In the secondary battery type fuel cell system having any one of the first to third configurations, the water replenishment unit is configured to supply the gas flow between the power generation / electrolysis unit and a gas inflow side of the hydrogen generation unit. It is preferable to adopt a configuration (fourth configuration) in which water is supplied to the road.

  The secondary battery type fuel cell system of the fourth configuration further includes an oxidation degree detection unit that detects an oxidation degree of the hydrogen generation unit, and based on a detection result of the oxidation degree detection unit, It is preferable to adopt a configuration (fifth configuration) in which the water supply section supplies water before the degree of oxidation exceeds a predetermined upper limit.

  According to the secondary battery type fuel cell system according to the present invention, water supply is performed except when the power generation / electrolysis unit is generating power and when the power generation / electrolysis unit is performing electrolysis. The power generation and charging will not become unstable. Therefore, stable power generation and charging are possible.

1 is a schematic diagram showing a schematic configuration of a secondary battery type fuel cell system according to an embodiment of the present invention. It is a figure for demonstrating the example of the timing which performs water replenishment. It is a figure for demonstrating the example of the timing which performs water replenishment. It is a figure for demonstrating the example of the timing which performs water replenishment. It is a figure for demonstrating the example of the timing which performs water replenishment. It is a figure for demonstrating the example of the timing which performs water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the temperature control at the time of water replenishment. It is a figure for demonstrating the example of the circulating gas amount control at the time of water replenishment. It is a figure for demonstrating the example of the circulating gas amount control at the time of water replenishment. It is a figure for demonstrating the example of the circulating gas amount control at the time of water replenishment. It is a figure for demonstrating the example of the circulating gas amount control at the time of water replenishment. It is a figure for demonstrating the example of the circulating gas amount control at the time of water replenishment. It is a figure for demonstrating the time of water supply. It is a figure for demonstrating the time of water supply. It is a figure for demonstrating the time of water supply. It is a figure for demonstrating the time of water supply.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not restricted to embodiment mentioned later.

  FIG. 1 shows a schematic configuration of a secondary battery type fuel cell system according to an embodiment of the present invention. The secondary battery type fuel cell system according to the present embodiment includes a hydrogen generating member 1, a fuel cell unit 2, a heater 3 for heating the hydrogen generating member 1, a heater 4 for heating the fuel cell unit 2, and hydrogen generation. A container 5 for housing the member 1 and the heater 3, a container 6 for housing the fuel cell part 2 and the heater 4, and a pipe for circulating a gas containing hydrogen and water vapor between the hydrogen generating member 1 and the fuel cell part 2. 7, a pump 8 that forcibly circulates gas between the hydrogen generating member 1 and the fuel cell unit 2, a heat insulating container 9, a pipe 10 for supplying air to the air electrode 2C of the fuel cell unit 2, A pipe 11 for discharging air from the air electrode 2C of the fuel cell part 2, a pressure sensor 12 for detecting the gas pressure in the pipe 11, and an oxidization degree detection part 13 for detecting the degree of oxidation of the hydrogen generating member 1 I have.

  The heat insulating container 9 accommodates the containers 5 and 6, a part of each of the pipes 7, 10, and 11, the pressure sensor 12, and the oxidation degree detection unit 13. The oxidation degree detection unit 13 is, for example, a device that detects the degree of oxidation based on a change in the weight of the hydrogen generation member 1, or the degree of oxidation based on a change in the permeability of the hydrogen generation member 1 when the hydrogen generation member 1 is Fe. And a device for detecting.

  In addition, the secondary battery type fuel cell system according to the present embodiment includes a switch unit 14, a power generation circuit unit 15, a current sensor 16, a charging circuit unit 17, a system controller 23 that controls the entire system, and water supply. Department.

  The switch unit 14 alternatively selects the power generation circuit unit 15 and the charging circuit unit 17 as the connection destination of the fuel cell unit 2. The power generation circuit unit 15 generates power to be supplied to the external load 100 using the output power of the fuel cell unit 2. The current sensor 16 detects a current flowing from the power generation circuit unit 15 to the external load 100. The charging circuit unit 17 generates power to be supplied to the fuel cell unit 2 using the output power of the external power source 200.

  In the present embodiment, the water replenishment section is constituted by a water storage chamber 18, a steam chamber 19, a heater 20, and opening / closing valves 21 and 22. Note that the water replenishment unit may of course have a configuration other than the present embodiment. The procedure in which the water replenishing unit of this embodiment replenishes the pipe 7 with water (water vapor) under the control of the system controller 23 is as follows. First, the opening / closing valve 21 is opened to introduce water stored in the water storage chamber 18 into the steam chamber 19, and then the opening / closing valve 21 is closed. Water is vaporized into steam by being introduced into the steam chamber 19 having a large volume. After the steam chamber 19 is heated by the heater 19 and the pressure in the steam chamber 19 is made higher than the pressure in the pipe 7, the open / close valve 22 is opened to introduce water vapor in the steam chamber 19 into the pipe 7, and then opened and closed Close the valve 21.

  In the present embodiment, the water replenishing unit replenishes the piping with water between the fuel cell unit 2 and the gas inflow side of the hydrogen generating unit 1. As a result, the water (steam) supplied to the pipe 7 is immediately reacted with the hydrogen generating member 1, and the fuel electrode 2B of the fuel cell unit 2 is oxidized and deteriorated with a temporary increase in the water vapor concentration due to the water supply. Can be prevented. Moreover, in this embodiment, the pump 8 is not arrange | positioned between the part in which the water of the piping 7 is replenished, and the gas inflow side of the hydrogen generating member 1. FIG. As a result, the replenished water (water vapor) is immediately reacted with the hydrogen generating member 1, and the pump 8 can be prevented from being oxidized and deteriorated with a temporary increase in the water vapor concentration due to water replenishment. Further, in order to immediately react the water (water vapor) supplied to the pipe 7 with the hydrogen generating member 1, in this embodiment, the system controller 23 is based on the detection result of the oxidation degree detection unit 13. Before the degree of oxidation exceeds a predetermined upper limit value (for example, 95%), the water replenishing section is made to replenish water.

  In FIG. 1, illustration of a power transmission line other than between the fuel cell unit 2 and the external load 100 and the external power source 200, a control line for transmitting a control signal, and the like is omitted in order to prevent the drawing from being complicated. doing. Moreover, you may provide a temperature sensor etc. around the hydrogen generation member 1 and the fuel cell part 2 as needed. Further, instead of the pump 8, other circulators such as a compressor, a fan, and a blower may be used, and the gas may be naturally circulated by gas diffusion without providing the circulator such as the pump 8.

As the hydrogen generating member 1, for example, a metal is used as a base material, and a metal or metal oxide is added to the surface thereof. Hydrogen is generated by an oxidation reaction with water vapor, and can be regenerated by a reduction reaction with hydrogen. Can be used. Examples of the base metal include Ni, Fe, Pd, V, Mg, and alloys based on these, and Fe is particularly preferable because it is inexpensive and easy to process. Examples of the added metal include Al, Rh, Pd, Cr, Ni, Cu, Co, V, and Mo. Examples of the added metal oxide include SiO ₂ and TiO ₂ . However, the metal used as a base material and the added metal are not the same material. In the present embodiment, a hydrogen generation member mainly composed of Fe is used as the hydrogen generation member 1.

The hydrogen generating member mainly composed of Fe can generate hydrogen by consuming water vapor by an oxidation reaction represented by the following formula (1).
4H ₂ O + 3Fe → 4H ₂ + Fe ₃ O ₄ (1)

When the oxidation reaction of iron shown in the above formula (1) proceeds, the change from iron to iron oxide proceeds and the remaining amount of iron decreases, but the reverse reaction of the above formula (1), that is, the following (2 The hydrogen generating member 1 can be regenerated by the reduction reaction shown in the formula. The iron oxidation reaction shown in the above formula (1) and the reduction reaction in the following formula (2) can also be performed at a low temperature of less than 600 ° C.
4H ₂ + Fe ₃ O ₄ → 3Fe + 4H ₂ O (2)

  In the hydrogen generating member 1, it is desirable to increase the surface area per unit volume in order to increase the reactivity. As a measure for increasing the surface area per unit volume of the hydrogen generating member 1, for example, the main body of the hydrogen generating member 1 may be made into fine particles, and the fine particles may be molded. Examples of the fine particles include a method of crushing particles by crushing using a ball mill or the like. Further, the surface area of the fine particles may be further increased by generating cracks in the fine particles by a mechanical method or the like, and the surface area of the fine particles is further increased by roughening the surface of the fine particles by acid treatment, alkali treatment, blasting, etc. It may be increased.

  The hydrogen generating member 1 may have, for example, a form in which fine particles are formed into pellet-like particles and a large number of these particles are filled in the space, and the fine particles are solidified leaving a gap through which gas passes. There may be.

  As shown in FIG. 1, the fuel cell unit 2 has an MEA structure (membrane / electrode assembly) in which a fuel electrode 2B and an air electrode 2C as an oxidant electrode are bonded to both surfaces of an electrolyte membrane 2A. Although FIG. 1 illustrates a structure in which only one MEA is provided, a plurality of MEAs may be provided, or a plurality of MEAs may be stacked.

  As a material of the electrolyte membrane 2A, for example, a solid oxide electrolyte using yttria-stabilized zirconia (YSZ) can be used. For example, Nafion (trademark of DuPont), a cationic conductive polymer, an anion conductive polymer Solid polymer electrolytes such as, but not limited to, those that pass hydrogen ions, those that pass oxygen ions, and those that pass hydroxide ions can be used as fuel cell electrolytes. Any material that satisfies the characteristics is acceptable. In the present embodiment, an electrolyte that passes oxygen ions or hydroxide ions, for example, a solid oxide electrolyte using yttria-stabilized zirconia (YSZ) is used as the electrolyte membrane 2A.

In the case of a solid oxide electrolyte, the electrolyte membrane 2A can be formed using an electrochemical vapor deposition method (CVD-EVD method; Chemical Vapor Deposition _- Electrochemical Vapor Deposition) or the like. If there is, it can be formed using a coating method or the like.

  Each of the fuel electrode 2B and the air electrode 2C can be configured by, for example, a catalyst layer in contact with the electrolyte membrane 2A and a diffusion electrode laminated on the catalyst layer. As the catalyst layer, for example, platinum black or a platinum alloy supported on carbon black can be used. Further, as a material for the diffusion electrode of the fuel electrode 2B, for example, carbon paper, Ni—Fe cermet, Ni—YSZ cermet, or the like can be used. Moreover, as a material of the diffusion electrode of the air electrode 2C, for example, carbon paper, La—Mn—O-based compound, La—Co—Ce-based compound, or the like can be used. Each of the fuel electrode 2B and the air electrode 2C can be formed by using, for example, vapor deposition.

When the switch unit 24 selects the power generation circuit unit 15 under the control of the system controller 23, the fuel cell unit 2 and the external load 100 are electrically connected. And when the fuel cell part 2 is generating electric power, reaction of following (3) Formula occurs in the fuel electrode 2B. The system controller 23 can confirm whether or not the fuel cell unit 2 is generating power from the detection result of the current sensor 16.
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (3)

The electrons generated by the reaction of the above expression (3) reach the air electrode 2C through the external load 100, and the reaction of the following expression (4) occurs in the air electrode 2C.
(1/2) O ₂ + 2e ⁻ → O ²⁻ (4)

And the oxygen ion produced | generated by reaction of said (4) Formula reaches | attains the fuel electrode 2B through electrolyte membrane 2A. By repeating the above series of reactions, the fuel cell unit 2 performs a power generation operation. Further, as can be seen from the above equation (3), during the power generation operation of the secondary battery type fuel cell system according to the present embodiment, H ₂ is consumed and H ₂ O is generated on the fuel electrode 2B side. .

From the above equations (3) and (4), the reaction in the fuel cell unit 2 during the power generation operation of the secondary battery type fuel cell system according to the present embodiment is as shown in the following equation (5).
H ₂ + (1/2) O ₂ → H ₂ O (5)

On the other hand, the hydrogen generating member 1 is produced by the oxidation reaction shown in the above formula (1), and H ₂ produced on the fuel electrode 2B side of the fuel cell unit 2 during power generation of the secondary battery type fuel cell system according to this embodiment. O is consumed to produce H ₂ .

  When the oxidation reaction of iron shown in the above formula (1) proceeds, the change from iron to iron oxide proceeds and the remaining amount of iron decreases, but the hydrogen generating member is reduced by the reduction reaction shown in the above formula (2). 1 can be regenerated, and the secondary battery type fuel cell system according to this embodiment can be charged.

When the switch unit 24 selects the charging circuit unit 17 under the control of the system controller 23 during charging of the secondary battery type fuel cell system according to the present embodiment, the fuel cell unit 2 and the external power source 200 are electrically connected. . In the fuel cell unit 2, when the secondary battery type fuel cell system according to the present embodiment is charged, an electrolysis reaction represented by the following formula (6), which is a reverse reaction of the formula (5), occurs, and the fuel electrode 2B H ₂ O is consumed on the side and H ₂ is generated. In the hydrogen generating member 1, the reduction reaction shown in the above equation (2) occurs, and the H ₂ generated on the fuel electrode 2B side of the fuel cell unit ₂ is consumed. And H ₂ O is produced.
H ₂ O → H ₂ + (1/2) O ₂ (6)

<Timing for water supply>
The example of the timing which performs water replenishment is demonstrated with reference to FIGS. In the following description, the power generation mode means a mode in which the fuel cell unit 2 is generating power, and the charging mode means a mode in which the fuel cell unit 2 is electrolyzed and the hydrogen generating member 1 is regenerated. The water replenishment mode means a mode in which the water replenishment unit replenishes water, and the stop mode means that the fuel cell unit 2 does not perform power generation or electrolysis and the water replenishment unit replenishes water. Means no mode. 2 to 6 and FIGS. 7 to 22 to be described later, the shaded time zone is a water supply mode in which water supply is performed.

  In the present embodiment, the water supply mode does not overlap with the power generation mode and the charging mode. That is, since water supply is performed except when the fuel cell unit 2 is generating power and when the fuel cell unit 2 is performing electrolysis, power generation and charging are not unstable due to water supply. Therefore, stable power generation and charging are possible.

  For example, when the secondary battery type fuel cell system according to the present embodiment is a system that generates power during the day and charges at night, before the daytime power generation mode ends and enters the night charge mode, the water supply mode is set. (See FIG. 2). In another example, the water supply mode is set before the night charging mode is completed and the daytime power generation mode is entered (see FIG. 3). In general, since the stability of power generation is given priority over the stability of charging, the example shown in FIG. 2 is preferable to the example shown in FIG.

  Further, for example, when the secondary battery type fuel cell system according to the present embodiment is a system that generates power during the day and charges it at night, and stops the power generation and electrolysis of the fuel cell unit after the charging is completed, Supply water (see FIG. 4). That is, a part of the stop mode is changed to the water supply mode.

  In addition, for example, after the secondary battery type fuel cell system according to the present embodiment generates power during the day, the power generation and electrolysis of the fuel cell unit is temporarily stopped, and then charging is started. In the case of a system that stops power generation and electrolysis, water supply is performed during any stoppage (see FIG. 5). That is, a part of the stop mode is changed to the water supply mode.

  In addition, when it is necessary to supply water during the charging mode, charging may be temporarily stopped to supply water (see FIG. 6). That is, the water supply mode may be interrupted during the charging mode.

<Temperature control during water supply>
An example of temperature control during water replenishment will be described with reference to FIGS. 7 to 13, the thick line indicates the circulating gas temperature, that is, the gas temperature in the pipe 7.

  Here, the circulating gas temperature, that is, the gas temperature in the pipe 7 may be directly detected by providing a temperature sensor in the pipe 7, or by providing a temperature sensor provided in the hydrogen generating member 1 or the fuel cell unit 2. It may be detected indirectly in consideration of the correlation between the temperature of the generating member 1 or the fuel cell unit 2 and the temperature of the pipe 7. Further, a heater may be provided in the pipe 7 to directly heat the gas in the pipe 7, or the gas in the pipe 7 may be indirectly heated by the heater 3 or the heater 4.

  In the water replenishment mode, the water (water vapor) replenished to the pipe 7 can be made into a gaseous state by controlling the circulating gas temperature (for example, by maintaining the circulating gas temperature at 100 ° C. or higher at 1 atm).

  For example, the circulating gas temperature in the water supply mode is set to be the same as the circulating gas temperature in the power generation mode (see FIG. 7). In another example, the circulating gas temperature in the water supply mode is set to be the same as the circulating gas temperature in the charging mode (see FIG. 8). In these examples, since the circulating gas temperature is not changed at the start of the water supply mode, switching from the power generation mode or the charge mode to the water supply mode can be performed in a short time.

  In addition, since it is not necessary to keep the circulating gas temperature constant in the water supply mode, in the water supply mode, the circulating gas temperature is gradually changed toward the set temperature of the circulating gas temperature in the mode after the end of the water supply mode. It is also possible (see FIG. 9).

  Further, when the secondary battery type fuel cell system according to the present embodiment is a system in which the stop mode is set, even if the circulating gas temperature in the water supply mode is set to be the same as the circulating gas temperature in the stop mode Good (see FIG. 10).

  Even when the secondary battery type fuel cell system according to the present embodiment is a system in which the stop mode is set, the circulating gas temperature in the water supply mode is made the same as the circulating gas temperature in the power generation mode or the charging mode. It may be set (see FIG. 11), and the circulating gas temperature may be gradually changed as in FIG. 9 (see FIG. 12).

  The circulating gas temperature in the water supply mode is set to an intermediate temperature between the set temperature of the circulating gas in the mode before the start of the water supply mode and the set temperature of the circulating gas in the mode after the end of the water supply mode. You may do (refer FIG. 13). By doing in this way, switching with water supply mode and the mode before and behind that can be performed in a short time.

<Circulating gas amount control during water supply>
An example of circulating gas amount control at the time of water supply will be described with reference to FIGS. 14 to 18, the thick line indicates the amount of circulating gas, that is, the gas flow rate in the pipe 7. The gas flow rate in the pipe 7 can be adjusted by, for example, the pump 8.

  For example, the amount of circulating gas in the water supply mode is set to be the same as the amount of circulating gas in the power generation mode (see FIG. 14). In another example, the circulating gas amount in the water supply mode is set to be the same as the circulating gas amount in the charging mode (see FIG. 15). In these examples, since the amount of circulating gas is not changed at the start of the water supply mode, switching from the power generation mode or the charge mode to the water supply mode can be performed in a short time.

  Further, when the secondary battery type fuel cell system according to the present embodiment is a system in which the stop mode is set, the circulating gas amount in the water replenishment mode may be set to be the same as the circulating gas amount in the stop mode. Good (see FIG. 16). If the circulating gas amount in the stop mode is set to zero, the circulating gas amount in the water replenishment mode must not be zeroed in order to quickly restore the original increase in water vapor concentration due to water replenishment. Is desirable. For example, the circulating gas amount in the water replenishment mode is set to the same setting as the circulating gas amount in the power generation mode or the charging mode (see FIG. 17), or smaller than in the power generation operation and the charging operation (see FIG. 18). Good.

<Time for water supply>
The timing of water supply will be described with reference to FIGS. In FIG. 20, the alternate long and short dash line indicates the amount of gas remaining in the pipe 7. The amount of gas remaining in the pipe 7 can be detected by, for example, the pressure sensor 12. If it is difficult to detect the amount of circulating gas (hydrogen and water) using only the pressure sensor 12, a gas composition detector (such as a dew point meter) may be provided.

  For example, the frequency of water replenishment is calculated based on the amount of circulating gas containing hydrogen leaked per unit time and the volume of the piping 7 so that the battery performance can be guaranteed without water replenishment. A constant cycle shorter than that is stored in the system controller 23 in advance, and water is replenished at the fixed cycle (FIG. 19). The fixed period here is a relatively long period such as several days or months, and does not need to coincide with the minute unit or the hour unit. For this reason, even if water replenishment is performed at a constant cycle, the water replenishment mode can be prevented from overlapping with the power generation mode and the charging mode.

  The frequency of water replenishment may be determined by appropriately detecting the amount of gas remaining in the pipe 7 and calculating the timing at which the system controller 23 replenishes water based on the detection result. For example, the time when the amount of gas remaining in the pipe 7 becomes less than the threshold may be set as the timing for replenishing water. However, if the timing of replenishing the water thus obtained is during the power generation mode or the charging mode, the water replenishment may be started after waiting for the power generation mode or the charging mode to end (see FIG. 20). . When the charging mode is in progress, the water supply mode may be interrupted during the charging mode.

  In addition, an input unit or the like that receives a user's instruction may be provided in the secondary battery type fuel cell system according to the present invention so that the user can instruct the timing of water supply. When the system accepts an instruction for water supply by the user, if it is in the charging mode, if it is in the power generation mode or the charging mode, it is only necessary to start water supply after waiting for the power generation mode or the charging mode to end (See FIG. 21). In addition, when in the charging mode, the water supply mode may be interrupted during the charging mode (see FIG. 22).

<Others>
In the embodiment described above, a solid oxide electrolyte is used as the electrolyte membrane 2A of the fuel cell unit 2, and water is generated on the fuel electrode 2B side during power generation. According to this configuration, water is generated on the side where the hydrogen generating member 1 is provided, which is advantageous for simplification and miniaturization of the apparatus. On the other hand, as a fuel cell disclosed in Japanese Patent Application Laid-Open No. 2009-99491, a solid polymer electrolyte that allows hydrogen ions to pass through may be used as the electrolyte membrane 2A of the fuel cell unit 2. However, in this case, since water is generated on the air electrode 2C side that is the oxidant electrode of the fuel cell unit 2 during power generation, a flow path for propagating this water to the hydrogen generating member 1 is provided. Just do it. In each of the above-described embodiments, one fuel cell unit 2 performs both power generation and water electrolysis. However, a fuel cell (for example, a solid oxide fuel cell dedicated to power generation) and a water electrolyzer (for example, water) The solid oxide fuel cell dedicated to electrolysis) may be connected to the hydrogen generating member 1 in parallel on the gas flow path.

  In the above-described embodiment, the hydrogen generating member 1 and the fuel cell unit 2 are accommodated in separate containers. However, the hydrogen generating member 1 and the fuel cell unit 2 may be accommodated in the same container. When the hydrogen generating member 1 and the fuel cell unit 2 are accommodated in the same container, the hydrogen generating member 1 and the fuel cell unit 2 are arranged at a predetermined interval, and the hydrogen generating member 1 and the fuel cell unit 2 are arranged. Are arranged in contact with each other. In the former, the space between the hydrogen generating member 1 and the fuel cell unit 2 becomes a gas flow path, and in the latter, the gap of the hydrogen generating member 1 becomes a gas flow path.

  In the above-described embodiment, air is used as the oxidant gas, but an oxidant gas other than air may be used.

DESCRIPTION OF SYMBOLS 1 Hydrogen generating member 2 Fuel cell part 2A Electrolyte membrane 2B Fuel electrode 2C Air electrode 3, 4, 20 Heater 5, 6 Container 7, 10, 11 Piping 8 Pump 9 Heat insulation container 12 Pressure sensor 13 Oxidation detection part 14 Switch part 15 Power generation circuit section 16 Current sensor 17 Charging circuit section 18 Water storage chamber 19 Steam chamber 21, 22 Open / close valve 23 System controller 100 External load 200 External power supply

Claims (5)

Hydrogen generation part that can release hydrogen by oxidation reaction and can be regenerated by reduction reaction,
A power generation / electrolysis unit having a power generation function for generating power using hydrogen supplied from the hydrogen generation unit and an electrolysis function for electrolyzing water vapor supplied from the hydrogen generation unit during regeneration of the hydrogen generation unit;
A gas flow path for circulating a gas containing hydrogen and water vapor between the hydrogen generation unit and the power generation / electrolysis unit;
A secondary battery type fuel cell system comprising a water replenishment unit for replenishing water to the gas flow path,
The secondary battery type fuel characterized in that the water replenishing unit replenishes water except when the power generation / electrolysis unit is generating power and when the power generation / electrolysis unit is performing electrolysis Battery system. A temperature control unit for controlling the temperature of the gas flow path;
2. The secondary battery type fuel cell system according to claim 1, wherein the temperature control unit controls the temperature of the gas flow path when water is supplied by the water supply unit. 3. A flow rate controller for controlling the flow rate of the gas containing hydrogen and water vapor present in the gas flow path;
The said flow control part controls the flow volume of the gas containing hydrogen and water vapor | steam which exists in the said gas flow path at the time of the water replenishment which the said water replenishment part is replenishing with water. Item 5. The secondary battery type fuel cell system according to Item 2.   The said water replenishment part replenishes water to the said gas flow path between the said power generation / electrolysis part and the gas inflow side of the said hydrogen generation part, The any one of Claims 1-3 characterized by the above-mentioned. The secondary battery type fuel cell system according to one item. An oxidation degree detection unit for detecting an oxidation degree of the hydrogen generation unit;
5. The water supply unit according to claim 4, wherein the water supply unit supplies water before the degree of oxidation of the hydrogen generation unit exceeds a predetermined upper limit value based on a detection result of the oxidation degree detection unit. Secondary battery type fuel cell system.