JP2014075248A - Fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell system having high durability.SOLUTION: The fuel cell system comprises: a fuel generation material for generating a fuel gas by chemical reaction and being recyclable by reductive reaction; a solid oxide type fuel cell unit for generation power by reaction of an oxidant gas containing oxygen with the fuel gas supplied from the fuel generation material; a circulation piping for circulating gas between the fuel generation material and the fuel electrode of the fuel cell unit; and a switching unit disposed in the circulation piping and used for switching a passage to either of a first state in which a gas discharged from the fuel generation material is supplied to the fuel electrode of the fuel cell unit or a second state in which a gas introduced from the outside is supplied to the fuel electrode of the fuel cell unit.

Description

  The present invention relates to a solid oxide which generates power by a reaction of a fuel generating member that generates fuel gas by an oxidation reaction and can be regenerated by a reduction reaction, an oxidant gas containing oxygen, and a fuel gas supplied from the fuel generating member. The present invention relates to a fuel cell system including a physical fuel cell unit.

  A solid oxide fuel cell includes a solid oxide electrolyte membrane using, for example, yttria-stabilized zirconia (YSZ) or a lanthanum gallate system (for example, LSGM represented by the general formula LaSrMgGaO), 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.

  Although the solid oxide fuel cell needs to have a higher operating temperature than the solid polymer fuel cell, it has the advantage of higher power generation efficiency than the solid polymer fuel cell.

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

  Patent Document 1 discloses a fuel cell system in which a solid oxide fuel cell and iron (hydrogen generating member) are combined. In the fuel cell system, iron (hydrogen generating member) generates hydrogen by an oxidation reaction with water vapor during the power generation operation of the system, and iron oxide (oxidized hydrogen generating member) is reduced by a reduction reaction with hydrogen during the charging operation of the system. Played.

  Patent Document 1 describes operations, conditions, and the like during operation of the fuel cell system, but does not describe assembly and maintenance of the fuel cell system.

For example, when considering the replacement of piping or the like by maintenance, the operation is generally performed in the atmosphere from the viewpoint of workability. Then, the pipe or the like if removed in the air, since the iron (hydrogen generating member) is exposed to air, is oxidized by oxygen in air to the Fe ₂ O _3.

In order to return the fuel cell system to a power generation operation state after the maintenance is completed, it is necessary to reduce and regenerate Fe ₂ O ₃ (oxidized hydrogen generating member).

Here, as a method of reducing the Fe ₂ O ₃ (oxidized hydrogen generating member) is circulated gas between Fe ₂ O ₃ (oxidized hydrogen generating member) and solid oxide fuel fuel electrode side of the battery After replacing the air in the gas flow path for water vapor with water vapor, the fuel cell system is operated in the energy storage mode described in Patent Document 1 to electrolyze water vapor in the solid oxide fuel cell, how to reduce Fe ₂ O ₃ with hydrogen produced by electrolysis (oxidized hydrogen generating member), or, Fe ₂ O ₃ (oxidized hydrogen generating member) and a solid oxide fuel cell anode side of There is a method of reducing Fe ₂ O ₃ (oxidized hydrogen generating member) by substituting air in a gas flow path for circulating gas between them with hydrogen.

  In the former method, the period from the replacement of the air in the gas flow path with water vapor to the electrolysis of the solid oxide fuel cell (mainly from the normal temperature to the electrolysis operating temperature of the solid oxide fuel cell (for example, During the period required to raise the temperature to about 800 ° C.), the gas flow path is filled with high-concentration water vapor. Then, the fuel electrode of the solid oxide fuel cell is oxidized by high concentration of water vapor, and the fuel electrode may be cracked or peeled off due to volume expansion due to oxidation, etc., which may deteriorate the performance of the solid oxide fuel cell. there were.

In the latter method, Fe ₂ O ₃ (oxidized hydrogen generating member) is reduced to Fe ₃ O ₄ by the reduction reaction of the following formula (1), and further by the reduction reaction of the following formula (2). Reduced to Fe.
3Fe ₂ O ₃ + H ₂ → 2Fe ₃ O ₄ + H ₂ O (1)
Fe ₃ O ₄ + 4H ₂ → 3Fe + 4H ₂ O (2)

  However, the reduction rate in the above equation (1) is very fast, and the gas composition ratio of water vapor and hydrogen in the chemical equilibrium in the above equation (1) is almost 100: 0. Since hydrogen is consumed quickly and water vapor is generated, the gas flow path is also filled with high-concentration water vapor in the latter method. Then, the fuel electrode of the solid oxide fuel cell is oxidized by high concentration of water vapor, and the fuel electrode may be cracked or peeled off due to volume expansion due to oxidation, etc., which may deteriorate the performance of the solid oxide fuel cell. there were.

  Patent Document 2 discloses a fuel cell system in which a hydrogen generation unit and a power generation / electrolysis unit are combined, and a gas containing hydrogen and water vapor that circulates between the hydrogen generation unit and the power generation / electrolysis unit. A fuel cell system including a water replenishment unit that replenishes water in an existing space is disclosed. However, when water is replenished by a water replenishment unit in a space where hydrogen and water vapor containing gas circulating between the hydrogen generation unit and the power generation / electrolysis unit exist, the water vapor concentration in the space increases. The fuel electrode of the solid oxide fuel cell is oxidized by the water vapor having a concentration, and the fuel electrode may be cracked or peeled due to volume expansion due to the oxidation and the performance of the solid oxide fuel cell may be deteriorated.

  In view of the above situation, an object of the present invention is to provide a highly durable fuel cell system.

  In order to achieve the above object, a fuel cell system according to the present invention generates a fuel gas by an oxidation reaction and is regenerated by a reduction reaction, an oxidant gas containing oxygen, and supplied from the fuel generation member. A solid oxide fuel cell unit that generates power by reaction with a fuel gas, a circulation pipe for circulating gas between the fuel generating member and the fuel electrode of the fuel cell unit, and the circulation pipe A first state in which the gas discharged from the fuel generating member is supplied to the fuel electrode of the fuel cell unit, and the gas discharged from the fuel generating member is discharged to the outside and introduced from the outside A configuration (first configuration) is provided that includes a switching unit that switches the flow path to either the second state in which the gas is supplied to the fuel electrode of the fuel cell unit. The second state is configured by a state in which the gas discharged from the fuel generating member is discharged to the outside and the gas introduced from the outside is simultaneously supplied to the fuel electrode of the fuel cell unit. Alternatively, the gas is discharged from the fuel generating member and the gas is discharged to the outside. The gas introduced from the outside is supplied to the fuel electrode of the fuel cell unit. May be.

  In the fuel cell system of the first configuration, the second state is such that the gas discharged from the fuel generating member is discharged to the outside, and the gas introduced from the outside is supplied to the fuel electrode of the fuel cell unit, Furthermore, it is good also as a structure (2nd structure) which is the state which supplies the gas introduce | transduced from the outside to the said fuel generation member, and discharges | emits the gas discharged | emitted from the fuel electrode of the said fuel cell part outside.

  In the fuel cell system of the second configuration, supply of the gas introduced from the outside to the fuel generating member, discharge of the gas discharged from the fuel generating member to the outside, and the fuel cell of the gas introduced from the outside The supply to the fuel electrode of the unit and the discharge of the gas discharged from the fuel electrode of the fuel cell unit to the outside may be performed simultaneously in the second state (third configuration).

  In the fuel cell system having any one of the first to third configurations, the first connector, the second connector paired with the first connector, the third connector, and the third connector are paired. And a first open / close valve disposed between the first connector and the fuel generating member in the vicinity of the first connector, and a second connector. An on-off valve is disposed between the second connector and the fuel cell portion and in the vicinity of the second connector, and a third on-off valve is provided between the third connector and the fuel generating member. And a fourth open / close valve is disposed between the fourth connector and the fuel cell unit and in the vicinity of the fourth connector, and the first connector is disposed near the third connector. Open / close valve, the second open / close valve It said third opening and closing valve, and the fourth on-off valve may be configured to be included in the switching unit (fourth configuration).

  According to the fuel cell system of the present invention, from the first state in which the gas discharged from the fuel generating member is supplied to the fuel electrode of the fuel cell unit by the switching unit disposed on the circulation pipe, from the fuel generating member. The flow path can be switched to the second state in which the exhausted gas is discharged to the outside and the gas introduced from the outside is supplied to the fuel electrode of the fuel cell unit. For example, the oxidized fuel generating member is reduced after the maintenance is completed. Thus, when the regeneration is performed in the second state, it is possible to prevent the high concentration oxidizing gas discharged from the fuel generating member from being supplied to the fuel electrode of the fuel cell unit. Therefore, the fuel electrode of the solid oxide fuel cell is oxidized by the high-concentration oxidizing gas, and the fuel electrode is cracked or peeled due to volume expansion due to the oxidation and the performance of the solid oxide fuel cell is deteriorated. No fear. That is, according to the present invention, a highly durable fuel cell system can be realized.

1 is a schematic diagram showing a schematic configuration of a fuel cell system according to a first embodiment of the present invention. 1 is a schematic diagram showing a schematic configuration of a fuel cell system according to a first embodiment of the present invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 2nd Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 3rd Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 4th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 4th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 5th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 5th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 5th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 6th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 6th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 6th Embodiment of this invention. It is a schematic diagram which shows schematic structure of the fuel cell system which concerns on 6th Embodiment of this invention.

  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.

<First Embodiment>
1A and 1B are schematic views showing a schematic configuration of a fuel cell system according to a first embodiment of the present invention. The fuel cell system according to the present embodiment includes a fuel generating member 1 that generates fuel gas by an oxidation reaction and can be regenerated by a reduction reaction, an oxidant gas containing oxygen, and a fuel gas supplied from the fuel generating member 1. And a solid oxide fuel cell unit 2 (hereinafter referred to as a fuel cell unit 2) that generates power by reaction. As shown in FIGS. 1A and 1B, the fuel cell unit 2 has an MEA structure (membrane / electrode assembly) in which a fuel electrode 2B and an oxidant electrode 2C are bonded to both surfaces of a solid oxide electrolyte membrane 2A. . 1A and 1B illustrate a structure in which only one MEA is provided, a plurality of MEAs may be provided, or a plurality of MEAs may be stacked.

  The fuel cell system according to the present embodiment includes a heater 3 for heating the fuel generating member 1, a heater 4 for heating the fuel cell unit 2, a container 5 for housing the fuel generating member 1 and the heater 3, A container 6 housing the fuel cell unit 2 and the heater 4, a circulation pipe 7 for circulating gas between the fuel generating member 1 and the fuel electrode 2B, a container 5, a container 6, a circulation pipe 7, and A pump 8 that circulates a gas present in a space surrounded by the solid oxide electrolyte membrane 2A between the fuel generating member 1 and the fuel electrode 2B, a four-way valve 9, a gas inlet 10, and a gas outlet 11. Is further provided. Instead of the pump 8, other circulators such as a blower and a compressor may be used, and the pump 8 and other circulators replacing the pump 8 may not be provided. Moreover, you may provide a temperature sensor etc. around the fuel generation member 1 and the fuel cell part 2 as needed.

  The four-way valve 9 is disposed on the circulation pipe 7, and has a first state in which the gas discharged from the fuel generating member 1 is supplied to the fuel electrode of the fuel cell unit 2, and the gas discharged from the fuel generating member 1. It functions as a switching unit that switches the flow path to either the second state in which the gas discharged to the outside and introduced from the outside to the fuel electrode 2B of the fuel cell unit 2 is supplied. During power generation and charging of the fuel cell system according to the present embodiment, the gas flow path is switched to the first state by the four-way valve 9 as shown in FIG. 1A. On the other hand, for example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, the gas flow path is switched to the second state by the four-way valve 9 as shown in FIG. 1B.

  In the following description, a case where a fuel generating member made of a fine particle compressed body whose base material (main component) is iron is used as the fuel generating member 1 and hydrogen is used as the fuel gas will be described.

The fuel cell unit 2 is electrically connected to an external load (not shown) during power generation of the fuel cell system according to the present embodiment. In the fuel cell unit 2, the following reaction (3) occurs in the fuel electrode 2B during power generation of the fuel cell system according to the present embodiment.
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (3)

The electrons generated by the reaction of the above formula (3) pass through an external load (not shown) and reach the oxidant electrode 2C, and the reaction of the following formula (4) occurs at the oxidant electrode 2C.
1 / 2O ₂ + 2e ⁻ → O ²⁻ (4)

And the oxygen ion produced | generated by reaction of said (4) Formula reaches | attains the fuel electrode 2B through 2 A of solid oxide electrolyte membranes. 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 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 fuel cell system according to the present embodiment is as shown in the following equation (5).
H ₂ + 1 / 2O ₂ → H ₂ O (5)

On the other hand, the fuel generating member 1 consumes H ₂ O generated on the fuel electrode 2B side of the fuel cell unit 2 during power generation of the fuel cell system according to the present embodiment by an oxidation reaction expressed by the following equation (6). To produce H ₂ .
3Fe + 4H ₂ O → Fe ₃ O ₄ + 4H ₂ (6)

  When the oxidation reaction of iron shown in the above formula (6) proceeds, the change from iron to iron oxide proceeds and the remaining amount of iron decreases, but by the reverse reaction (reduction reaction) of the above formula (6), The fuel generating member 1 can be regenerated and the fuel cell system according to this embodiment can be charged.

When the fuel cell system according to this embodiment is charged, the fuel cell unit 2 is connected to an external power source (not shown). In the fuel cell unit 2, when the fuel cell system according to the present embodiment is charged, an electrolysis reaction shown in the following equation (7) which is a reverse reaction of the above equation (5) occurs, and H ₂ is generated on the fuel electrode 2B side. O is consumed and H ₂ is generated, and the fuel generating member 1 undergoes a reduction reaction represented by the following equation (8), which is a reverse reaction of the oxidation reaction represented by the above equation (6), and the fuel electrode of the fuel cell unit 2 H ₂ produced on the 2B side is consumed and H ₂ O is produced.
H ₂ O → H ₂ + 1 / 2O ₂ (7)
Fe ₃ O ₄ + 4H ₂ → 3Fe + 4H ₂ O (8)

  In the present embodiment, the fuel generating member 1 and the fuel cell unit 2 are heated to about 600 ° C. by the heaters 3 and 4 both during power generation and charging of the fuel cell system according to the present embodiment.

  Further, for example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, hydrogen is introduced from the outside into the gas inlet 10 and the gas discharged from the fuel generating member 1 is discharged from the gas outlet 11 to the outside. Discharge. Thereby, the air in the gas flow path for circulating the gas between the fuel generating member 1 and the fuel electrode 2B side of the fuel cell unit 2 can be replaced with hydrogen, and the oxidized fuel generating member 1 Even when the water is reduced and high-concentration water vapor is generated, the high-concentration water vapor is not supplied to the fuel electrode 2B of the fuel cell unit 2. Therefore, the fuel electrode 2B of the fuel cell unit 2 is oxidized by the high-concentration water vapor, and there is no possibility that the fuel electrode 2B is cracked or peeled due to volume expansion due to the oxidation and the performance of the fuel cell unit 2 is deteriorated. That is, durability is improved.

Second Embodiment
2A and 2B are schematic views showing a schematic configuration of a fuel cell system according to a second embodiment of the present invention. 2A and 2B, the same parts as those in FIGS. 1A and 1B are denoted by the same reference numerals. Hereinafter, differences between the present embodiment and the first embodiment of the present invention will be mainly described, and the description of the common points between the present embodiment and the first embodiment of the present invention will be omitted as appropriate.

  The fuel cell system according to this embodiment has a configuration in which the four-way valve 9 is removed from the fuel cell system according to the first embodiment, and on-off valves 13 to 15 are provided instead of the four-way valve 9. The opening / closing valve 14 is provided between the circulation pipe 7 and the gas inlet 10, the opening / closing valve 15 is provided between the circulation pipe 7 and the gas outlet 11, and the opening / closing valve 13 is provided with the opening / closing valve 14 and the opening / closing valve. 15 is provided.

  The on-off valves 13 to 15 are disposed on the circulation pipe 7 and are discharged from the fuel generation member 1 in a first state in which the gas discharged from the fuel generation member 1 is supplied to the fuel electrode of the fuel cell unit 2. It functions as a switching unit that switches the flow path to either the second state in which the gas is discharged to the outside and the gas introduced from the outside is supplied to the fuel electrode 2B of the fuel cell unit 2.

  In FIG. 2A and FIG. 2B, the white paint of each of the on-off valves 13 to 15 indicates an open state, and the black paint of each of the on-off valves 13 to 15 indicates a closed state. At the time of power generation and charging of the fuel cell system according to the present embodiment, as shown in FIG. 2A, the on-off valve 13 is opened, the on-off valves 14 and 15 are closed, and the gas flow path is the first. Switch to state. On the other hand, for example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, as shown in FIG. 2B, the opening / closing valve 13 is closed and the opening / closing valves 14 and 15 are opened, causing gas to enter. Are switched to the second state.

  The fuel cell system according to the present embodiment has the same effects as the fuel cell system according to the first embodiment of the present invention.

<Third Embodiment>
3A and 3B are schematic views showing a schematic configuration of a fuel cell system according to a third embodiment of the present invention. 3A and 3B, the same reference numerals are given to the same portions as those in FIGS. 1A and 1B. Hereinafter, differences between the present embodiment and the first embodiment of the present invention will be mainly described, and the description of the common points between the present embodiment and the first embodiment of the present invention will be omitted as appropriate.

  The fuel cell system according to the present embodiment removes the four-way valve 9, the gas inlet port 10, and the gas outlet port 11 from the fuel cell system according to the first embodiment of the present invention, and replaces them with the four-way valves 16 and 17 and the fuel. In this configuration, an electrode side gas inlet port 18, a fuel electrode side gas outlet port 19, a fuel generating member side gas inlet port 20, and a fuel generating member side gas outlet port 21 are provided.

  The four-way valves 16 and 17 are disposed on the circulation pipe 7 and are discharged from the fuel generating member 1 in a first state in which the gas discharged from the fuel generating member 1 is supplied to the fuel electrode of the fuel cell unit 2. It functions as a switching unit that switches the flow path to either the second state in which the gas is discharged to the outside and the gas introduced from the outside is supplied to the fuel electrode 2B of the fuel cell unit 2. At the time of power generation and charging of the fuel cell system according to the present embodiment, the gas flow path is switched to the first state by the four-way valves 16 and 17 as shown in FIG. 3A. On the other hand, for example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, the gas flow path is switched to the second state by the four-way valves 16 and 17 as shown in FIG. 3B.

  For example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, hydrogen is introduced from the outside into the fuel electrode side gas inlet 18 and the gas discharged from the fuel electrode 2B side of the fuel cell unit 2 is used as the fuel. While discharging to the outside from the pole side gas discharge port 19, hydrogen is introduced from the outside to the fuel generation member side gas introduction port 20, and the gas discharged from the fuel generation member 1 is discharged from the fuel generation member side gas discharge port 21 to the outside. Discharge

  Thereby, the air in the gas flow path for circulating the gas between the fuel generating member 1 and the fuel electrode 2B side of the fuel cell unit 2 can be replaced with hydrogen, and the oxidized fuel generating member 1 Even when the water is reduced and high-concentration water vapor is generated, the high-concentration water vapor is not supplied to the fuel electrode 2B of the fuel cell unit 2. Therefore, the fuel electrode 2B of the fuel cell unit 2 is oxidized by the high-concentration water vapor, and there is no possibility that the fuel electrode 2B is cracked or peeled due to volume expansion due to the oxidation and the performance of the fuel cell unit 2 is deteriorated. That is, durability is improved. In addition, since the gas flow path on the fuel generating member 1 side and the gas flow path on the fuel electrode 2B side of the fuel cell unit 2 are completely separated, the fuel generating member can be used even if a reverse gas flow occurs for some reason. There is no possibility that the high-concentration water vapor generated on one side is supplied to the fuel electrode 2B of the fuel cell unit 2.

<Fourth embodiment>
4A and 4B are schematic views showing a schematic configuration of a fuel cell system according to a fourth embodiment of the present invention. 4A and 4B, the same parts as those in FIGS. 3A and 3B are denoted by the same reference numerals. Hereinafter, differences between the present embodiment and the third embodiment of the present invention will be mainly described, and description of common points between the present embodiment and the third embodiment of the present invention will be omitted as appropriate.

  In the fuel cell system according to the present embodiment, the four-way valves 16 and 17 are removed from the fuel cell system according to the third embodiment of the present invention, and on-off valves 22 to 24 are provided instead of the four-way valve 16. Is provided with open / close valves 25-27. The on-off valve 23 is provided between the circulation pipe 7 and the fuel electrode side gas inlet 18, and the on-off valve 24 is provided between the circulation pipe 7 and the fuel generation member side gas inlet 20, and the on-off valve 22 Is provided between the opening / closing valve 23 and the opening / closing valve 24. The open / close valve 26 is provided between the circulation pipe 7 and the fuel electrode side gas discharge port 19, and the open / close valve 27 is provided between the circulation pipe 7 and the fuel generation member side gas discharge port 21 to open and close it. The valve 25 is provided between the opening / closing valve 26 and the opening / closing valve 27.

  The on-off valves 22 to 27 are arranged on the circulation pipe 7 and are discharged from the fuel generating member 1 in a first state in which the gas discharged from the fuel generating member 1 is supplied to the fuel electrode of the fuel cell unit 2. It functions as a switching unit that switches the flow path to either the second state in which the gas is discharged to the outside and the gas introduced from the outside is supplied to the fuel electrode 2B of the fuel cell unit 2.

  In FIGS. 4A and 4B, the white paint of the open / close valves 22 to 27 indicates the open state, and the black paint of the open / close valves 22 to 27 indicates the closed state. At the time of power generation and charging of the fuel cell system according to the present embodiment, as shown in FIG. 4A, the opening / closing valves 22 and 25 are opened, and the opening / closing valves 23, 24, 26, and 27 are closed and gas is discharged. Are switched to the first state. On the other hand, for example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, as shown in FIG. 4B, the opening and closing valves 22 and 25 are closed, and the opening and closing valves 23, 24, 26, and 27 are closed. Is opened and the gas flow path is switched to the second state.

  The fuel cell system according to the present embodiment has the same effects as the fuel cell system according to the third embodiment of the present invention.

<Fifth Embodiment>
5A, 5B, and 5C are schematic views showing a schematic configuration of a fuel cell system according to a fifth embodiment of the present invention. 5A, 5B, and 5C, the same parts as those in FIGS. 3A and 3B are denoted by the same reference numerals. Hereinafter, differences between the present embodiment and the third embodiment of the present invention will be mainly described, and description of common points between the present embodiment and the third embodiment of the present invention will be omitted as appropriate.

  In the fuel cell system according to this embodiment, the four-way valves 16 and 17 are removed from the fuel cell system according to the fourth embodiment of the present invention, a three-way valve 28 is provided instead of the four-way valve 16, and a three-way valve 17 is used instead of the four-way valve 17. A valve 29 is provided, a gas introduction port 10 is provided instead of the fuel electrode side gas introduction port 18 and the fuel generation member side gas introduction port 20, and a fuel electrode side gas discharge port 19 and a fuel generation member side gas discharge port 21 are substituted. The gas outlet 11 is provided.

  The three-way valve 28 is disposed on the circulation pipe 7 and has a first state in which the gas discharged from the fuel generating member 1 is supplied to the fuel electrode of the fuel cell unit 2 and the gas discharged from the fuel generating member 1. It functions as a switching unit that switches the flow path to either the second state in which the gas discharged to the outside and introduced from the outside to the fuel electrode 2B of the fuel cell unit 2 is supplied.

  For example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, the three-way valves 28 and 29 are first switched from the state shown in FIG. 5A to the state shown in FIG. 5B. The gas introduced into the gas inlet 10 and discharged from the fuel electrode 2B side of the fuel cell unit 2 is discharged to the outside from the gas outlet 11, and then the three-way valves 28 and 29 are changed from the state shown in FIG. 5B to FIG. 5C. After the switching is completed, hydrogen is again introduced from the outside into the gas inlet 10, and the gas discharged from the fuel generating member 1 is discharged from the gas outlet 11 to the outside.

  The fuel cell system according to the present embodiment has basically the same effects as the fuel cell system according to the third embodiment of the present invention, but the second state is the state shown in FIG. 5B and the state shown in FIG. 5C. Therefore, the time required from the start to the end of the second state is longer than that of the fuel cell system according to the third embodiment of the present invention.

<Sixth Embodiment>
6A, 6B, 6C, and 6D are schematic views showing a schematic configuration of a fuel cell system according to a sixth embodiment of the present invention. 6A, 6B, 6C, and 6D, the same parts as those in FIGS. 5A, 5B, and 5C are denoted by the same reference numerals. Hereinafter, differences between the present embodiment and the fifth embodiment of the present invention will be mainly described, and description of points common to the present embodiment and the fifth embodiment of the present invention will be omitted as appropriate.

In the fuel cell system according to the present embodiment, the three-way valves 28 and 29 are removed from the fuel cell system according to the fifth embodiment of the present invention, and on-off valves 30 to 32 are provided instead of the three-way valve 28, and instead of the three-way valve 29. Provided with a first connector 36 and a second connector 37 which are paired with each other, and a third connector 38 and a fourth connector 39 which are paired with each other. It is. The open / close valve 32 is provided between the circulation pipe 7 and the gas inlet 10, the open / close valve 30 is provided between the fuel generating member 1 and the open / close valve 32, and the open / close valve 31 is connected to the fuel cell unit 2 and the open / close valve. The opening / closing valve 35 is provided between the circulation pipe 7 and the gas outlet 11, the opening / closing valve 33 is provided between the fuel generating member 1 and the opening / closing valve 35, and the opening / closing valve 34. Is provided between the fuel cell unit 2 and the open / close valve 35.
The first to fourth connectors 36 to 39 provided on the circulation pipe 7 are connectors that enable connection and separation between the circulation pipes 7, and the first connector 36 is provided in the vicinity of the opening / closing valve 30. A second connector 37 is provided in the vicinity of the opening / closing valve 31, a third connector 38 is provided in the vicinity of the opening / closing valve 33, and a fourth connector 39 is provided in the vicinity of the opening / closing valve 34.

  The on-off valves 30 to 35 are disposed on the circulation pipe 7, and are discharged from the fuel generation member 1 in a first state in which the gas discharged from the fuel generation member 1 is supplied to the fuel electrode of the fuel cell unit 2. It functions as a switching unit that switches the flow path to either the second state in which the gas is discharged to the outside and the gas introduced from the outside is supplied to the fuel electrode 2B of the fuel cell unit 2.

  6A, FIG. 6B, FIG. 6C, and FIG. 6D, the white color of each of the on-off valves 30 to 35 indicates an open state, and the black color of each of the on-off valves 30 to 35 indicates a closed state. At the time of power generation and charging of the fuel cell system according to the present embodiment, as shown in FIG. 6A, the on-off valves 30, 32, 33, and 34 are in an open state, and the on-off valves 32 and 35 are in a closed state. Are switched to the first state. On the other hand, for example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, the opening / closing valves 30 to 35 are first switched from the state shown in FIG. 6A to the state shown in FIG. Hydrogen is introduced into the gas inlet 10 from the fuel electrode 2B side, and the gas discharged from the fuel electrode 2B side of the fuel cell unit 2 is discharged from the gas outlet 11 to the outside. Thereafter, the opening and closing valves 30 to 35 are opened from the state shown in FIG. Switching to the state shown in FIG. 6C, hydrogen is again introduced from the outside into the gas inlet 10 after the switching is completed, and the gas discharged from the fuel generating member 1 is discharged from the gas outlet 11 to the outside.

  The fuel cell system according to the present embodiment has the same effects as the fuel cell system according to the fifth embodiment of the present invention.

  Furthermore, since the fuel cell system according to the present embodiment can be separated into the fuel generating member side module 100 and the fuel cell unit side module 200 as shown in FIG. 6D, replacement or maintenance in module units is possible. It becomes. Since the open / close valves 30, 31, 33, and 34 can also be used as valves for enclosing gas in the gas flow path in the module, an increase in the number of components can be suppressed.

<Others>

  In each of the above-described embodiments, the fuel gas of the fuel cell unit 2 is hydrogen, but a reducing gas other than hydrogen, such as carbon monoxide or hydrocarbon, may be used as the fuel gas of the fuel cell unit 2. For example, when the oxidized fuel generating member is reduced and regenerated after the maintenance is completed, the same gas as the fuel gas may be introduced from the outside.

DESCRIPTION OF SYMBOLS 1 Fuel generating member 2 Solid oxide fuel cell part 2A Solid oxide electrolyte membrane 2B Fuel electrode 2C Oxidant electrode 3, 4 Heater 5, 6 Container 7 Circulation piping 8 Pump 9, 16, 17 Four-way valve 10 Gas inlet DESCRIPTION OF SYMBOLS 11 Gas discharge port 13-15, 22-27, 30-35 Open / close valve 18 Fuel electrode side gas introduction port 19 Fuel electrode side gas discharge port 20 Fuel generation member side gas introduction port 21 Fuel generation member side gas discharge port 28, 29 Three-way valve 36 1st connector 37 2nd connector 38 3rd connector 39 4th connector 100 Fuel generation member side module 200 Fuel cell part side module

Claims (4)

A fuel generating member that generates fuel gas by an oxidation reaction and can be regenerated by a reduction reaction;
A solid oxide fuel cell unit that generates power by a reaction between an oxidant gas containing oxygen and a fuel gas supplied from the fuel generating member;
A circulation pipe for circulating gas between the fuel generating member and the fuel electrode of the fuel cell unit;
A first state in which the gas discharged from the fuel generating member is disposed on the circulation pipe and supplied to the fuel electrode of the fuel cell unit; and the gas discharged from the fuel generating member is discharged to the outside. A fuel cell system comprising: a switching unit that switches a flow path to any one of a second state in which gas introduced from the outside is supplied to the fuel electrode of the fuel cell unit.   In the second state, the gas discharged from the fuel generating member is discharged to the outside, the gas introduced from the outside is supplied to the fuel electrode of the fuel cell unit, and the gas introduced from the outside is generated as the fuel. 2. The fuel cell system according to claim 1, wherein the fuel cell system is in a state of being supplied to the member and discharging the gas discharged from the fuel electrode of the fuel cell unit to the outside.   In the second state, supply of gas introduced from the outside to the fuel generation member, discharge of gas discharged from the fuel generation member to the outside, and fuel electrode of the fuel cell unit of gas introduced from the outside The fuel cell system according to claim 2, wherein the supply to the fuel cell and the discharge of the gas discharged from the fuel electrode of the fuel cell unit to the outside are performed simultaneously. A first connector; a second connector paired with the first connector; a third connector; and a fourth connector paired with the third connector on the circulation pipe;
A first on-off valve is disposed between the first connector and the fuel generating member and in the vicinity of the first connector;
A second on-off valve is disposed between the second connector and the fuel cell unit and in the vicinity of the second connector;
A third on-off valve is disposed between the third connector and the fuel generating member and in the vicinity of the third connector;
A fourth open / close valve is disposed between the fourth connector and the fuel cell unit and in the vicinity of the fourth connector;
The fuel cell according to any one of claims 1 to 3, wherein the first open / close valve, the second open / close valve, the third open / close valve, and the fourth open / close valve are included in the switching unit. system.