JP2014167935A - Solid oxide fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heat the inside of a module to a high temperature quickly, by supplying combustion gas in a state of higher temperature, and increasing the heat exchange efficiency of power generation oxidant gas furthermore.SOLUTION: A heat exchanger extends in the horizontal direction while covering a fuel cell stack, and has a combustion gas inlet through which the combustion gas flows in, at one end of extension. A thermal insulation material for suppressing heat conduction from the combustion gas generated in the combustion chamber to the heat exchanger is provided between the heat exchanger and a reformer. An exhaust passage having a straightener as a bottom surface and introducing the combustion gas generated in the combustion chamber to the combustion gas inlet of the heat exchanger is provided below the thermal insulation material. The combustion gas generated in the combustion chamber passes through an opening of the straightener provided above the center of a fuel cell stack, and introduced to the combustion gas inlet via the exhaust passage.

Description

  The present invention relates to a solid oxide fuel cell device that generates power using a fuel gas and an oxidant gas.

  A solid oxide fuel cell (hereinafter also referred to as “SOFC”) uses an oxide ion conductive solid electrolyte as an electrolyte, has electrodes attached to both sides thereof, and supplies fuel gas to one side. This is a fuel cell device that generates power by supplying an oxidant gas (air, oxygen, etc.) to the other side and generating a power generation reaction at a relatively high temperature.

  Specifically, the SOFC generally includes a plurality of tubular fuel cells each having a solid electrolyte layer sandwiched between a fuel electrode layer that is an inner electrode layer and an air electrode layer that is an outer electrode layer. An assembly (fuel cell stack) is provided, which operates when fuel gas and oxidant gas (air, oxygen, etc.) flow from one end side to the other end side of the fuel cell. From the outside of the SOFC, a gas to be reformed (city gas, etc.), which is a raw material gas, is supplied, and the gas to be reformed is introduced into a reformer containing a reforming catalyst, and reformed into a hydrogen-rich fuel gas. After being refined, it is configured to be supplied to the fuel cell assembly.

  The SOFC also includes a plurality of processes for reforming the fuel gas in the reformer in the start-up process, that is, a partial oxidation reforming (POX) reaction process (hereinafter also referred to as a POX reaction process), an autothermal process. Transition to power generation process through reforming (Auto Thermal Reforming: ATR) reaction process (hereinafter also referred to as ATR reaction process) and steam reforming (SR) reaction process (hereinafter also referred to as SR reaction process) Is configured to do. In the SOFC, the reformer, the fuel cell stack, and the like can be raised to the operating temperature by sequentially executing these steps.

  In such an SOFC, it is common to perform a partial oxidation reforming reaction step at the time of startup. For example, Patent Document 1 describes a start-up method for a reformer that can smoothly start the reformer by changing the reforming reaction at the start-up of the reformer.

JP 2004-10411 A

  However, the POX reaction process is an exothermic reaction, and if the amount of input air varies, depending on the situation, an abrupt exothermic reaction may occur, which may cause an excessive temperature rise and thus have a serious impact on the life of the reformer. It was. Patent Document 1 merely discloses a general technique for start-up control using the POX reaction, and there is no disclosure or suggestion of a technical idea that actively suppresses the occurrence of excessive temperature rise in the reformer. .

  Here, considering that one of the purposes of executing the POX reaction process is to raise the temperature of the reformer using an exothermic reaction, the reformer can be improved by some means without excessive exothermic reaction in the POX reaction process. If it is possible to quickly increase the temperature and shift to the SR reaction step at an early stage, it is possible to suppress the excessive temperature increase associated with the POX reaction.

  Therefore, the present invention has been made in view of such circumstances, and even if the partial oxidation reforming reaction in the reformer is suppressed, the present invention can be transferred to the SR reaction process at an early stage, thereby suppressing the excessive temperature rise. An object of the present invention is to provide a fuel cell device.

  In order to solve the above-described problems, a solid oxide fuel cell device according to the present invention is a solid oxide fuel cell device capable of generating electric power by a reaction between a supplied fuel gas containing hydrogen and an oxidant gas for power generation. In a solid oxide fuel cell device comprising a fuel cell stack in which a plurality of fuel cells are arranged, and a casing that accommodates the fuel cell stack therein, the solid oxide fuel cell device is provided above the fuel cell stack in the casing, A combustion chamber that generates combustion gas by burning the remaining fuel gas that has passed through the fuel cells, and a combustion chamber that is heated above the combustion chamber so as to be heated by the combustion gas in the casing. A reformer capable of reforming into a fuel gas, and a power generating oxidant gas and a combustion gas provided above the reformer to heat the power generating oxidant gas A heat exchanger that exchanges heat between the fuel cell stack, the heat exchanger extending in a horizontal direction over the fuel cell stack, and the combustion gas flowing into the extended one end A heat insulating material is provided between the heat exchanger and the reformer to suppress heat conduction from the combustion gas generated in the combustion chamber to the heat exchanger, and below the heat insulating material, It has an exhaust passage with a rectifying plate at the bottom that guides the combustion gas generated in the combustion chamber to the combustion gas inlet of the heat exchanger, and the combustion gas generated in the combustion chamber is provided above the center of the fuel cell stack. It passes through the opening of the rectifying plate and is led to the combustion gas inlet through the exhaust passage.

  Thus, in the present invention, by providing a heat insulating layer that suppresses heat conduction between the heat exchanger and the reformer, the combustion gas that has heated the reformer in the combustion chamber is in the heat exchanger case. Therefore, it has become possible to quickly raise the temperature of the reformer by increasing the amount of heat exchange with the reformer. In addition, a heat insulating layer that suppresses heat conduction acts so that the temperature rise is promoted from the inside of the heat exchanger, not the case of the heat exchanger. It becomes possible to quickly raise the temperature inside the quality device and the module. Thereby, the temperature of the reformer can be raised to a temperature at which steam reforming can be performed at an early stage without excessive POX reaction. As a result, it is possible to suppress the POX reaction, it is possible to suppress the amount of heat generated by the POX reaction, and it is possible to protect the reformer by suppressing the effect of excessive temperature rise of the reformer. Become.

  In the solid oxide fuel cell device according to the present invention, the heat insulating layer provided between the heat exchanger and the reformer is a heat insulating material having a low thermal conductivity.

  In this preferable embodiment, the heat insulating performance can be improved by providing the heat insulating material that positively suppresses the heat exchange amount with respect to the case of the heat exchanger. Therefore, the combustion gas can be supplied to the inside of the heat exchanger at a higher temperature, and the heat exchange efficiency of the oxidant gas for power generation can be further increased, so that the inside of the module can be quickly heated to a high temperature.

  In the solid oxide fuel cell device according to the present invention, an exhaust passage for discharging the combustion gas along the heat insulating material is further provided between the heat insulating material and the reformer, and an oxidation for power generation is provided. An oxidant gas inlet for power generation for supplying the oxidant gas into the heat exchanger is provided, and the exhaust passage includes an air layer in which the combustion gas stays in a region corresponding to the oxidant gas inlet for power generation. The heat insulation layer which comprises is further comprised.

  In this preferred embodiment, a heat insulating layer composed of an air layer in which combustion gas stays in a region corresponding to the oxidant gas inlet for power generation is further provided in the exhaust passage between the heat insulating material and the reformer. Because heat exchange between the low-temperature oxidant gas flowing in from the oxidant gas inlet and the combustion gas is suppressed, it is possible to reliably supply the heat exchanger with the temperature of the combustion gas maintained at a high temperature. Become. As a result, the heat exchange efficiency between the combustion gas and the oxidant gas for power generation can be increased, and the reformer can be heated by supplying high-temperature oxidant gas for power generation, thereby further suppressing the excessive temperature rise caused by the POX reaction. Is possible.

  According to the present invention, the heat exchange between the combustion gas and the heat exchanger case is suppressed, and the high-temperature combustion gas can be reliably supplied into the heat exchanger. Exchange efficiency can be improved. By improving the heat exchange efficiency, high-temperature power generation oxidant gas can be supplied in the start-up phase of the module at a low temperature, so the temperature of the reformer can be increased and the transition to the SR reforming process can be made early. can do. Therefore, it is possible to suppress the POX reaction, and it is possible to suppress the reformer deterioration due to excessive temperature rise.

It is a perspective view which shows the external appearance of the fuel cell module in embodiment of this invention. It is sectional drawing in the center vicinity of FIG. 1, Comprising: It is sectional drawing which shows the cross section seen from the A direction of FIG. It is sectional drawing in the center vicinity of FIG. 1, Comprising: It is sectional drawing which shows the cross section seen from the B direction of FIG. It is a perspective view which shows the state which removed some outer plates from the casing of FIG. FIG. 3 is a schematic diagram corresponding to FIG. 2, and is a schematic diagram showing flows of power generation air and combustion gas. FIG. 4 is a schematic diagram corresponding to FIG. 3, and is a schematic diagram showing flows of power generation air and combustion gas. It is a fragmentary sectional view which shows the fuel cell unit used for this embodiment. It is a perspective view which shows the structure of the fuel cell stack in this embodiment. It is a schematic diagram which shows the heat exchanger of FIG. It is a top view which shows the heat insulating material and heat storage part inside the fuel cell module shown in FIG. It is a top view which shows the heat storage part inside the fuel cell module in a modification. It is a schematic diagram which shows the flow of power generation air and combustion gas in a modification. It is a whole block diagram which shows the solid oxide fuel cell apparatus containing the fuel cell module shown in FIG. It is a block block diagram which shows the control structure of the solid oxide fuel cell apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  A fuel cell module used in a solid oxide fuel cell device according to an embodiment of the present invention will be described with reference to FIG. A fuel cell module 2 shown in FIG. 1 constitutes a part of a solid oxide fuel cell device. The solid oxide fuel cell device includes a fuel cell module 2 and an auxiliary unit. Details of the solid oxide fuel cell device and the auxiliary unit will be described later.

  In FIG. 1, the height direction of the fuel cell module 2 is the y-axis direction. The x axis and the z axis are defined along a plane perpendicular to the y axis, the direction along the short direction of the fuel cell module 2 is defined as the x axis direction, and the direction along the longitudinal direction of the fuel cell module 2 is defined as z. Axial direction. The x-axis, y-axis, and z-axis described in FIG. 2 and thereafter are based on the x-axis, y-axis, and z-axis in FIG. Further, the direction along the negative direction of the z axis is the A direction, and the direction along the positive direction of the x axis is the B direction.

  The fuel cell module 2 includes a casing 56 that accommodates fuel cells (details will be described later). The heat exchanger 22 is provided on the upper portion of the casing 56. The inside of the casing 56 is a sealed space. A reformed gas supply pipe 60 and a water supply pipe 62 are connected to the casing 56. On the other hand, a power generation air introduction pipe 74 and a combustion gas discharge pipe 82 are connected to the heat exchanger 22.

  The to-be-reformed gas supply pipe 60 is a pipe line that supplies a to-be-reformed gas for reforming such as city gas into the casing 56. The water supply pipe 62 is a pipe for supplying water used when steam reforming the gas to be reformed. The power generation air introduction pipe 74 is a pipe for supplying power generation air (oxidant gas) for causing a power generation reaction with the reformed fuel gas. The combustion gas discharge pipe 82 is a pipe line for discharging the combustion gas generated as a result of burning the fuel gas after the power generation reaction.

  Next, the inside of the fuel cell module 2 will be described with reference to FIGS. 2 is a cross-sectional view of the fuel cell module 2 as viewed from the direction A in FIG. 1 in the vicinity of the center thereof. 3 is a cross-sectional view of the fuel cell module 2 as viewed from the direction B in FIG. 2 in the vicinity of the center thereof. FIG. 4 is a perspective view showing a state where a part of the casing 56 covering the fuel cell assembly is removed from the fuel cell module 2 shown in FIG.

  As shown in FIGS. 2 to 4, the fuel cell assembly 12 of the fuel cell module 2 is entirely covered with a casing 56. As shown in FIG. 4, the fuel cell assembly 12 has a substantially rectangular parallelepiped shape that is longer in the A direction than in the B direction, and has an upper surface on the reformer 20 side, a lower surface on the fuel gas tank 68 side, A long side surface extending along the A direction and a short side surface extending along the B direction in FIG. 4 are provided.

  As shown in FIG. 6, the evaporative mixer 23 for evaporating the water supplied from the water supply pipe 62 is provided inside the reformer 20. The evaporative mixer 23 is heated by the combustion gas to convert water into water vapor, and to mix the water vapor, fuel gas (city gas) as the reformed gas, and air.

  The reformed gas supply pipe 60 and the water supply pipe 62 are both connected to the reformer 20 after being led into the casing 56. More specifically, as shown in FIG. 3, the reformer 20 is connected to an end on the right side in the drawing, which is an upstream end of the reformer 20.

  The reformer 20 is disposed further above the combustion chamber 18 formed above the fuel cell assembly 12. Therefore, the reformer 20 is heated by the combustion heat of the remaining fuel gas and air after the power generation reaction, and serves as an evaporative mixer 23 and partially oxidizes the fuel by chemically reacting the fuel gas and the oxidant gas. It is configured to serve as a reformer capable of generating hydrogen by both a reforming reaction for reforming and a steam reforming reaction by chemically reacting fuel and steam.

  The upper end of the fuel supply pipe 66 is connected to the downstream end of the reformer 20 (the left end in FIG. 3). The lower end side 66 a of the fuel supply pipe 66 is disposed so as to enter the fuel gas tank 68.

As shown in FIGS. 2 to 4, the fuel gas tank 68 is provided directly below the fuel cell assembly 12. A plurality of small holes (not shown) are formed along the longitudinal direction (A direction) on the outer periphery of the lower end side 66 a of the fuel supply pipe 66 inserted into the fuel gas tank 68. The fuel gas reformed by the reformer 20 is uniformly supplied in the longitudinal direction into the fuel gas tank 68 through the plurality of small holes (not shown). The fuel gas supplied to the fuel gas tank 68 is supplied into a fuel gas flow path (details will be described later) inside each fuel cell unit 16 constituting the fuel cell assembly 12, and the fuel cell unit 16 It rises up to reach the combustion chamber 18.

  Next, a structure for supplying power generation air to the inside of the fuel cell module 2 will be described with reference to FIGS. FIG. 5 is a schematic diagram corresponding to FIG. 2 and shows the flow of power generation air and combustion gas. FIG. 6 is a schematic diagram corresponding to FIG. 3, and similarly shows the flow of power generation air and combustion gas. As shown in these drawings, a heat exchanger 22 is provided above the reformer 20, and a heat insulating layer 81 is provided between the reformer 20 and the heat exchanger 22. Apart from the heat insulating layer 81, the casing 56 is covered with a heat insulating material 80. The heat exchanger 22 is provided with a plurality of combustion gas pipes 70 and a power generation air flow path 72 formed around the combustion gas pipes 70.

  A power generation air introduction pipe 74 is attached to one end side (the right end in FIG. 3) of the upper surface of the heat exchanger 22. With this power generation air introduction pipe 74, power generation air is introduced into the heat exchanger 22 from a power generation air flow rate adjustment unit (details will be described later).

  As shown in FIG. 2, a pair of outlet ports 76 a of the power generation air flow path 72 is formed on the other end side (the left end in FIG. 3) on the upper side of the heat exchanger 22. The outlet port 76a is connected to a pair of communication channels 76. Further, power generation air supply passages 77 are formed on the outer sides of both sides of the casing 56 of the fuel cell module 2 in the width direction (B direction: short side surface direction).

Therefore, power generation air is supplied to the power generation air supply path 77 from the outlet port 76 a of the power generation air flow path 72 and the communication flow path 76. The power generation air supply path 77 is formed along the longitudinal direction of the fuel cell assembly 12. Furthermore, in order to blow out the air for power generation toward each fuel cell unit 16 of the fuel cell assembly 12 in the power generation chamber 10 at a position corresponding to the lower side of the fuel cell assembly 12 below the fuel cell assembly 12. A plurality of outlets 78a and 78b are formed. The power generation air blown out from these air outlets 78 a and 78 b flows from the lower side to the upper side along the outer side of each fuel cell unit 16.

As shown in FIG. 6, a heat insulating layer 81 is formed between the heat exchanger 22 and the reformer 20. The heat insulation layer 81 is formed from the lower end of the combustion gas inlet 22a through which the combustion gas flows into the heat exchanger 22 to the lower end of the combustion gas discharge pipe 82 for discharging the combustion gas along the heat exchanger bottom surface 22b. The heat transfer from the combustion gas generated in the combustion chamber 18 to the heat exchanger 22 is suppressed. The heat insulating layer 81 only needs to have a function of suppressing the heat of the combustion gas from being transferred from the outer surface of the heat exchanger 22 to reach the inside of the heat exchanger 22. Various things can be selected according to the material and thickness of the member forming the outside of the exchanger 22. Therefore, the heat insulating layer 81 may be formed as an air layer in which only air is filled in the space surrounded by the metal plate, or the heat insulating member may be disposed in the space surrounded by the metal plate.

Subsequently, a structure for discharging combustion gas generated by combustion of fuel gas and power generation air will be described. In the combustion chamber 18 above the fuel cell unit 16, combustion gas is generated by burning the fuel gas that has not been used for the power generation reaction and the power generation air. This combustion gas rises in the combustion chamber 18 and reaches the rectifying plate 21. As shown in FIG. 6, the rectifying plate 21 is provided with an opening 21a, and the combustion gas is guided into the opening 21a. The combustion gas that has passed through the opening 21 a reaches the combustion gas inlet 22 a of the heat exchanger 22 through the exhaust passage 200 provided in the lower region of the heat insulating layer 81. In the exhaust passage 200, a heat reservoir 205 is formed in a corresponding region of the power generation air introduction pipe 74 so that the combustion gas is trapped. In the heat exchanger 22, a plurality of combustion gas pipes 70 (combustion gas passages) for discharging combustion gas are provided. A combustion gas discharge pipe 82 is connected to the downstream end side of these combustion gas pipes 70 so that the combustion gas is discharged to the outside.

  By providing the heat insulating layer 81 between the heat exchanger 22 and the reformer 20 as described above, the combustion gas is supplied to the heat exchanger 22 before the combustion gas flows into the combustion gas inlet 22a of the heat exchanger 22. Heat transfer can be suppressed. As a result, the combustion gas can flow into the heat exchanger 22 in a high temperature state, and the efficiency of heat exchange between the power generation air and the combustion gas can be improved. Thereby, since the power generation air can be supplied into the module chamber in a high temperature state, the reformer 20 is quickly raised to a temperature capable of steam reforming, and the reformer resulting from the partial oxidation reforming reaction Can be suppressed.

  Further, the heat insulating layer 81 may be formed of a heat insulating material that prevents air convection. Specifically, as a heat insulating material for preventing air convection, for example, a heat insulating material such as a vacuum heat insulating layer or a silica-based material can be used. By comprising in this way, since heat insulation performance can be improved rather than what provided the heat insulation layer 81 with the heat insulation layer of air, combustion gas can be supplied to a heat exchanger in a higher temperature state. The efficiency of heat exchange with the oxidant gas for power generation can be increased.

  In the present embodiment, the heat insulating layer 81 is formed from the lower end of the combustion gas inlet 22a to the lower end of the combustion gas discharge pipe 82, but the heat insulating material is formed in at least a part of the lower region of the heat exchanger 22b. You may comprise so that it may do. For example, the heat insulating material may be formed only in a region corresponding to the power generation air introduction pipe 74.

  By forming the heat insulating layer 81 in the region corresponding to the power generation air introduction pipe 74 in this way, the low temperature power generation oxidant gas flowing in from the power generation air introduction pipe 74 is transferred to the high temperature combustion chamber. Therefore, the module chamber can be maintained at a high temperature, and the temperature of the reformer can be increased. As a result, partial oxidation reforming reaction in the reformer can be suppressed, and excessive temperature rise can be suppressed.

  Next, the fuel cell unit 16 will be described with reference to FIG. FIG. 7 is a partial cross-sectional view showing the fuel cell unit 16 of the present embodiment.

  As shown in FIG. 7, the fuel cell unit 16 includes a fuel cell 84 and inner electrode terminals 86 respectively connected to the vertical ends of the fuel cell 84.

  The fuel cell 84 is a tubular structure extending in the vertical direction, and includes a cylindrical inner electrode layer 90 that forms a fuel gas flow path 88 therein, a cylindrical outer electrode layer 92, an inner electrode layer 90, and an outer side. An electrolyte layer 94 is provided between the electrode layer 92 and the electrode layer 92. The inner electrode layer 90 is a fuel electrode through which fuel gas passes and becomes a (−) electrode, while the outer electrode layer 92 is an air electrode in contact with air and becomes a (+) electrode.

Since the inner electrode terminals 86 attached to the upper end side and the lower end side of the fuel cell unit 16 have the same structure, the inner electrode terminal 86 attached to the upper end side will be specifically described here. The upper portion 90 a of the inner electrode layer 90 includes an outer peripheral surface 90 b and an upper end surface 90 c exposed to the electrolyte layer 94 and the outer electrode layer 92. The inner electrode terminal 86 is connected to the outer peripheral surface 90b of the inner electrode layer 90 through a conductive sealing material 96, and is further in direct contact with the upper end surface 90c of the inner electrode layer 90, thereby Electrically connected. A fuel gas passage 98 communicating with the fuel gas passage 88 of the inner electrode layer 90 is formed at the center of the inner electrode terminal 86.

  The inner electrode layer 90 includes, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, and Ni and ceria doped with at least one selected from rare earth elements. The mixture is formed of at least one of Ni and a mixture of lanthanum garade doped with at least one selected from Sr, Mg, Co, Fe, and Cu.

  The electrolyte layer 94 includes, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, lanthanum gallate doped with at least one selected from Sr and Mg, Formed from at least one of the following.

  The outer electrode layer 92 includes, for example, lanthanum manganite doped with at least one selected from Sr and Ca, lanthanum ferrite doped with at least one selected from Sr, Co, Ni and Cu, Sr, Fe, Ni and Cu. It is formed from at least one of lanthanum cobaltite doped with at least one selected from the group consisting of silver and silver.

  Next, the fuel cell stack 14 will be described with reference to FIG. FIG. 8 is a perspective view showing the fuel cell stack 14 of the present embodiment.

  As shown in FIG. 8, the fuel cell stack 14 includes 16 fuel cell units 16, and a lower end side and an upper end side of these fuel cell units 16 are respectively made of ceramic fuel gas tank upper plate 68 a and It is supported by the upper support plate 100. The fuel gas tank upper plate 68a and the upper support plate 100 are formed with through holes through which the inner electrode terminal 86 can pass.

  Furthermore, a current collector 102 and an external terminal 104 are attached to the fuel cell unit 16. The current collector 102 electrically connects the inner electrode terminal 86 attached to the inner electrode layer 90 that is a fuel electrode and the outer peripheral surface of the outer electrode layer 92 that is the air electrode of the adjacent fuel cell unit 16. To do.

  Further, the external terminals 104 are connected to the inner electrode terminals 86 at the upper and lower ends of the two fuel cell units 16 located at the ends of the fuel cell stack 14. These external terminals 104 are connected to the external terminals 104 of the fuel cell unit 16 at the end of the adjacent fuel cell stack 14, and all 160 fuel cell units 16 are connected in series. Yes.

  Next, the heat exchanger 22 will be further described with reference to FIG. FIG. 9 is a diagram schematically showing the heat exchanger 22 shown in FIG.

  As described above, the heat exchanger 22 generates power by using the heat of the combustion gas generated by the combustion of the fuel gas that has not been used for the power generation reaction in the fuel cell assembly 12 and the power generation air. The power generation air used for the reaction is heated. The heat exchanger 22 in the present embodiment is characterized in that a turbulent flow generation member 71 is provided in the combustion gas pipe 70. That is, by providing the turbulent flow generation member 71 in the combustion gas pipe 70, it is possible to improve the heat exchange efficiency at low temperatures and improve the operation efficiency at high temperatures. Hereinafter, the turbulent flow generation member 71 will be described in detail.

  The turbulent flow generation member 71 is a member that generates a turbulent flow in the combustion gas flowing through the combustion gas pipe 70. The turbulent flow generation member 71 is formed by spirally twisting a rod-shaped member. By disposing such a spiral turbulent flow generation member 71 in the combustion gas pipe 70, the combustion gas flowing in the combustion gas pipe 70 can be turbulent and diffused. Thereby, since the flow distance and flow time of the combustion gas in the combustion gas pipe 70 can be extended, the heat exchange efficiency from the combustion gas to the power generation air can be improved.

  The turbulent flow generation member 71 is formed of a member that expands and contracts in the longitudinal direction of the turbulent flow generation member 71 according to the temperature. That is, when the temperature rises, the length of the turbulent flow generation member 71 increases, and when the increased temperature decreases, the length of the turbulent flow generation member 71 decreases.

  By forming the turbulent flow generating member 71 in a spiral shape, the length of the turbulent flow generating member 71 is increased when compared with a linear member formed of the same material and the same length as the turbulent flow generating member 71. can do. That is, the turbulent flow generation member 71 has a larger expansion rate than the cylindrical combustion gas pipe 70 in the longitudinal direction. The turbulent flow generation member 71 is not limited to being formed of the same material as that of the combustion gas pipe 70, and may be formed of a material that is more easily thermally expanded than the combustion gas pipe 70. By forming it with a material that easily undergoes thermal expansion, the effect of reducing turbulent flow at a high temperature described later can be further enhanced.

  As shown in FIG. 9, the turbulent flow generation member 71 is formed to have the same length as the length of the combustion gas pipe 70 at a low temperature such as 0 ° C., for example. When the turbulent flow generating member 71 is disposed in the combustion gas pipe 70, the end 71 a located on the upstream side of the combustion gas pipe 70 is fixed to the combustion gas pipe 70 and is located on the downstream side of the combustion gas pipe 70. The end 71b is arranged without being fixed to the combustion gas pipe 70.

  By arranging the turbulent flow generating member 71 in this way, for example, at a high temperature such as during power generation, the turbulent flow generating member 71 extends due to thermal expansion, and the turbulent flow generating member 71 extends from the downstream opening of the combustion gas pipe 70. The end 71b side protrudes.

  11 and 12 are views showing a fuel cell module as a modification. FIG. 11 is a plan view showing a heat reservoir inside the fuel cell module according to a modification. FIG. 12 is a schematic diagram showing the flow of power generation air and combustion gas.

As shown in FIG. 12, an exhaust passage 200 a is provided between the heat exchanger 22 and the reformer 20. As shown in FIGS. 11 and 12, a heat reservoir 205a is formed in the exhaust passage 200a in a region corresponding to the power generation air introduction pipe 74 so that the combustion gas that has passed through the opening 21a stagnate. Specifically, the opening 21 a for introducing the combustion gas into the exhaust passage 200 a is arranged on the inlet side where the combustion gas is sent to the heat exchanger 22. Therefore, the heat reservoir 205a is formed farther than the flow of the combustion gas flowing from the opening 21a to the heat exchanger 22, and the flow of the combustion gas can be retained more reliably. The speed can be reduced.

  With this configuration, the flow rate of the combustion gas in the heat reservoir 205a can be surely made smaller than the flow rate of the combustion gas passing from the opening 21a to the combustion gas inlet 22a. The stream can be retained. As a result, even when a low-temperature oxidant gas flows from the power generation air introduction pipe 74, heat transfer into the combustion chamber 18 is prevented by the heat reservoir 205a, so that the module chamber can be maintained at a high temperature. Thereby, the temperature of the reformer 20 can be raised, and the occurrence of overheating due to the partial oxidation reforming reaction can be suppressed.

  Next, a solid oxide fuel cell device including the above-described fuel cell module 2 will be described with reference to FIGS. 13 and 14. FIG. 13 is an overall configuration diagram showing a solid oxide fuel cell device including the fuel cell module 2. FIG. 14 is a block diagram showing a control structure of the solid oxide fuel cell device shown in FIG. As shown in FIG. 13, the solid oxide fuel cell 1 includes a fuel cell module 2 and an auxiliary unit 4.

  The fuel cell module 2 includes a housing 6. Inside the housing 6, a sealed space 8 is formed surrounded by a heat insulating material 30 (see FIG. 5). A fuel cell assembly 12 that performs a power generation reaction with fuel gas and oxidant gas (air) is disposed in a power generation chamber 10 that is a lower portion of the sealed space 8.

  The fuel cell assembly 12 includes ten fuel cell stacks 14. The fuel cell stack 14 includes 16 fuel cell units 16 (single cell, see FIG. 7). The fuel cell assembly 12 has 160 fuel cell units 16, and all of these fuel cell units 16 are connected in series.

  A combustion chamber 18 is formed in the sealed space 8 of the fuel cell module 2 above the power generation chamber 10 described above. In the combustion chamber 18, the remaining fuel gas that has not been used for the power generation reaction and the remaining oxidant gas (air) are combusted to generate combustion gas (exhaust gas).

  Above the combustion chamber 18 is disposed a reformer 20 that reforms the gas to be reformed and generates fuel gas. The reformer 20 is heated to a temperature at which the reforming reaction can be performed by the combustion heat of the combustion gas described above. Further, a heat exchanger 22 for heating an oxidant gas (power generation air) introduced from the outside by heat of the combustion gas is disposed above the reformer 20.

  The auxiliary unit 4 stores a pure water tank 26 that stores water from a water supply source 24 such as a tap water and makes it pure water with a filter, and a water flow rate adjusting unit 28 that adjusts the flow rate of water supplied from the water storage tank. (Corresponding to the water supply means of the present invention, including a “water pump” driven by a motor). The auxiliary unit 4 also includes a gas shut-off valve 32 that shuts off the fuel gas supplied from a fuel supply source 30 such as city gas, a desulfurizer 36 for removing sulfur from the fuel gas, and a flow rate of the fuel gas. A fuel flow rate adjustment unit 38 (corresponding to the fuel gas supply means of the present invention, including a “fuel pump” driven by a motor, etc.) is provided.

Further, the auxiliary unit 4 includes an electromagnetic valve 42 that shuts off air that is an oxidant gas supplied from an air supply source 40, and a reforming air flow rate adjusting unit 44 that adjusts the flow rate of air (the reforming of the present invention). This includes an “air blower” driven by a motor, etc.) and a power generation air flow rate adjustment unit 45 (corresponding to the power generating oxidant gas supply means of the present invention. Driven by a motor. A first heater 46 that heats the reforming air supplied to the reformer 20, and a second heater 48 that heats the power generating air supplied to the power generation chamber. And. The first heater 46 and the second heater 48 are provided in order to efficiently raise the temperature at the time of startup, but may be omitted.

  The fuel cell module 2 is connected to a hot water production apparatus 50 to which exhaust gas is supplied. The hot water production apparatus 50 is supplied with tap water from the water supply source 24, and the tap water is heated by the heat of the exhaust gas and supplied to a hot water storage tank of an external hot water heater (not shown). The fuel cell module 2 is provided with a control box 52 for controlling the amount of fuel gas supplied and the like. The fuel cell module 2 is connected to an inverter 54 that is a power extraction unit (power conversion unit) for supplying the power generated by the fuel cell module to the outside.

  As shown in FIG. 14, the solid oxide fuel cell 1 includes a control unit 110 (corresponding to the control means of the present invention). The control unit 110 includes an operation device 112 having operation buttons such as “ON” and “OFF” for operation by the user, and a display for displaying various data such as a power generation output value (wattage). A device 114 and a notification device 116 that issues a warning (warning) in an abnormal state are connected. The notification device 116 may be connected to a remote management center and notify the management center of an abnormal state.

  Signals from various sensors described below are input to the control unit 110. The combustible gas detection sensor 120 is for detecting a gas leak, and is attached to the fuel cell module 2 and the auxiliary unit 4. The CO detection sensor 122 indicates whether or not CO in the exhaust gas originally discharged to the outside through the combustion gas discharge chamber 80 or the like has leaked to an external housing (not shown) that covers the fuel cell module 2 and the accessory unit 4. It is for detection. The hot water storage state detection sensor 124 is for detecting the temperature and amount of hot water in a water heater (not shown).

  The power state detection sensor 126 is for detecting the current and voltage of the inverter 54 and the distribution board (not shown). The power state detection sensor 126 is configured to detect an open circuit voltage. The power generation air flow rate detection sensor 128 is for detecting the flow rate of the power generation air supplied to the power generation chamber 10. The reforming air flow rate sensor 130 is for detecting the flow rate of the reforming air supplied to the reformer 20. The fuel flow sensor 132 is for detecting the flow rate of the fuel gas supplied to the reformer 20.

  The water flow rate sensor 134 is for detecting the flow rate of pure water (steam) supplied to the reformer 20. The water level sensor 136 is for detecting the water level of the pure water tank 26. The pressure sensor 138 is for detecting the pressure on the upstream side outside the reformer 20. The exhaust temperature sensor 140 is for detecting the temperature of the exhaust gas flowing into the hot water production apparatus 50.

  The power generation chamber temperature sensor 142 (corresponding to the temperature acquisition means of the present invention) is provided on the front side and the back side in the vicinity of the fuel cell assembly 12, and detects the temperature in the vicinity of the fuel cell stack 14, This is for estimating the temperature of the fuel cell stack 14 (that is, the fuel cell 84 itself).

  The combustion chamber temperature sensor 144 (corresponding to the temperature acquisition means of the present invention) is for detecting the temperature of the combustion chamber 18. The combustion chamber temperature sensor 144 is provided between the fuel cell assembly 12 and the ignition device 83. The combustion chamber temperature sensor 144 also functions as an ignition confirmation temperature sensor for determining whether or not the fuel cell 84 has been ignited. The exhaust gas chamber temperature sensor 146 is for detecting the temperature of the exhaust gas in the combustion gas discharge chamber.

  The reformer temperature sensor 148 is for detecting the temperature of the reformer 20, and calculates the temperature of the reformer 20 from the inlet temperature and the outlet temperature of the reformer 20. As shown in FIGS. 3 and 4, the reformer temperature sensor 148 is provided in the vicinity of each of the inlet side and the outlet side of the reformer 20. The outside air temperature sensor 150 is for detecting the temperature of the outside air when the solid oxide fuel cell (SOFC) is disposed outdoors. Further, a sensor for measuring the humidity or the like of the outside air may be provided.

  Signals from these sensors are sent to the control unit 110. The control unit 110 sends control signals to the water flow rate adjustment unit 28, the fuel flow rate adjustment unit 38, the reforming air flow rate adjustment unit 44, and the power generation air flow rate adjustment unit 45 based on the data based on these signals. Each flow rate in the unit is controlled. Further, the control unit 110 sends a control signal to the inverter 54 to control the power supply amount.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

2 Fuel cell module 10 Power generation chamber 12 Fuel cell assembly 14 Fuel cell stack 16 Fuel cell unit 18 Combustion chamber 20 Reformer 21 Rectifier plate 21a Opening 22 Heat exchanger 22a Combustion gas inlet 22b Heat exchanger bottom 23 Evaporation mixer 80 Heat insulating material 81 Heat insulating layer 200 Exhaust passage 205 Heat reservoir 56 Casing 60 Reformed gas supply pipe 62 Water supply pipe 66 Fuel supply pipe 66a Lower end side 68 Fuel gas tank 68a Fuel gas tank upper plate 70 Combustion gas pipe 71 Disturbance Flow generating member 71a End 71b End 72 Power generation air flow path 74 Power generation air introduction pipe 76 Connection flow path 76a Outlet port 77 Power generation air supply paths 78a, 78b Outlet 82 Combustion gas discharge pipe 84 Fuel cell 86 Inside Electrode terminal 88 Fuel gas flow path 90 Inner electrode layer 90a Upper part 90b Outer peripheral surface 90c Upper end surface 92 Outside Side electrode layer 94 Electrolyte layer 96 Sealing material 98 Fuel gas flow path 100 Upper support plate 102 Current collector 104 External terminal

Claims (3)

A fuel cell stack in which a plurality of solid oxide fuel cells that can generate electric power by a reaction between a supplied fuel gas containing hydrogen and an oxidant gas for power generation are arranged, and the fuel cell stack inside A solid oxide fuel cell device comprising a housing for housing,
A combustion chamber provided in the casing above the fuel cell stack and burning the remaining fuel gas that has passed through the fuel cell to generate combustion gas;
A reformer provided above the combustion chamber so as to be heated by the combustion gas in the casing and capable of reforming the supplied fuel gas into a fuel gas containing hydrogen;
A heat exchanger provided above the reformer and configured to exchange heat between the power generation oxidant gas and the combustion gas in order to heat the power generation oxidant gas,
The heat exchanger extends in the horizontal direction so as to cover the fuel cell stack, and has a combustion gas inlet into which the combustion gas flows into one end of the extension.
Between the heat exchanger and the reformer, a heat insulating material that suppresses heat conduction from the combustion gas generated in the combustion chamber to the heat exchanger is provided,
Below the heat insulating material, there is an exhaust passage having a rectifying plate as a bottom surface that guides the combustion gas generated in the combustion chamber to the combustion gas inlet of the heat exchanger,
The combustion gas generated in the combustion chamber passes through an opening of the rectifying plate provided above the center of the fuel cell stack, and is guided to the combustion gas inlet through the exhaust passage. Solid oxide fuel cell device. In claim 1,
The heat insulating material is formed at least along the bottom surface of the heat exchanger from below one end of the heat exchanger extending in the horizontal direction to below the other end. Solid oxide fuel cell device. In claim 2,
The solid oxide fuel cell device, wherein the heat insulating material is a heat insulating material of a silica-based material.

Images