JP5985872B2 - Solid oxide fuel cell system - Google Patents

Description

  The present invention relates to a solid oxide fuel cell system that generates power using fuel gas.

  As a fuel cell system, one using a fuel cell stack in which a plurality of solid oxide fuel cells are stacked is known (see, for example, Patent Document 1). In this solid oxide fuel cell, a fuel electrode is provided on one side of a solid electrolyte that conducts oxygen ions, an air electrode is provided on the other side, and yttria-doped zirconia is generally used as an electrolyte material. It is used. In such a fuel cell stack, electric power is generated by causing an electrochemical reaction between hydrogen, carbon monoxide, hydrocarbons in the fuel gas and oxygen in the oxidant at a high temperature of 600 to 1000 ° C. The solid oxide fuel cell system is being developed as a promising power generation technology because it can generate power with higher power generation efficiency than other types of fuel cell systems and gas engines.

  In this solid oxide fuel cell system, the fuel gas is steam reformed by a reformer, and the reformed fuel gas (reformed fuel gas) is supplied to the fuel electrode side of the fuel cell stack. For the steam reforming, a steam catalyst such as a ruthenium-based catalyst or a nickel-based catalyst is used. For example, nickel in a metal state is used for the fuel electrode of the fuel cell stack. When city gas is used as fuel gas, the city gas contains a small amount of sulfur component, and this sulfur component poisons the steam reforming catalyst of the reformer and the fuel electrode of the fuel cell stack. For example, a steam reforming catalyst such as a ruthenium-based catalyst or a nickel-based catalyst is poisoned only by containing about 0.1 ppm of a sulfur component in the fuel gas, and about 90% of its surface is in a short time. It is covered with sulfur and carbon deposition is observed, and the catalyst activation is significantly reduced. For this reason, a desulfurizer is provided on the upstream side of the reformer, and the fuel gas from which the sulfur component has been removed by this desulfurizer is fed to the downstream reformer.

  On the other hand, a copper-zinc-based desulfurization agent is known as a desulfurization agent filled in the desulfurizer (see, for example, Patent Document 2). This desulfurizing agent is used to remove dimethyl sulfide and t-butyl mercaptan contained as an odorant in a natural gas fuel gas (for example, city gas) mainly composed of methane, and has a temperature of 150 to 300 ° C. By maintaining in this temperature range, high desulfurization performance is exhibited, and sulfur components contained in the fuel gas can be removed. Here, high desulfurization performance means that the integral flow rate of the fuel gas until the sulfur component passes through the desulfurizer is large.

JP 2008-243589 A JP-A-11-139803

  Of these solid oxide fuel cell systems that are relatively small (with a rated output of less than several tens of kW), reducing maintenance costs is one of the important requirements. Therefore, there is a demand for a desulfurizer that does not require replacement of the desulfurizing agent over a long period of time, and in order to achieve this, it is important to properly control the temperature of the desulfurizing agent. It has become one.

  When the temperature of the desulfurizing agent is properly maintained, the amount of the desulfurizing agent required to operate the solid oxide fuel cell system having a rated output of 1 kW, for example, for 10 years is about 1.0 to 1.2 L, When the rated output is 3 kW, the amount of the desulfurizing agent is about 3.6 L, and when the rated output is 5 kW, the amount of the desulfurizing agent is about 6 L. For this reason, if it is attempted to be maintenance-free for 10 years, a considerably large amount of desulfurizing agent is required, and the container housing of the desulfurizer that accommodates this desulfurizing agent also becomes large, and the desulfurizing agent filled in such a container housing is expensive. It becomes difficult to maintain in the temperature range where desulfurization performance is obtained.

  An object of the present invention is to provide a solid oxide fuel cell system capable of maintaining a desulfurizing agent in a desulfurizer within a temperature range in which high desulfurization performance can be obtained.

The solid oxide fuel cell system according to claim 1 of the present invention includes a fuel gas supply means for supplying fuel gas through a fuel gas supply flow path, and steam reforming the fuel gas from the fuel gas supply means And a fuel cell stack composed of a plurality of fuel cells that generate power by oxidation and reduction of the reformed fuel gas and oxidant reformed by the reformer, and does not contribute to power generation A combustion chamber provided on the downstream side of the fuel cell stack for burning surplus fuel gas; air supply means for supplying air as an oxidant to the fuel cell stack through an air supply channel; A heat exchanger provided in a combustion exhaust gas discharge flow path for discharging combustion exhaust gas from the fuel cell stack and the combustion chamber; the reformer; the fuel cell stack; A storage housing for storing a firing chamber, wherein the heat exchanger exchanges heat between the combustion exhaust gas flowing through the combustion exhaust gas discharge flow path and the air flowing through the air supply flow path, and the heat exchange A solid oxide fuel cell system in which air heated by a container is supplied to the fuel cell stack,
The fuel gas supply flow path is provided with a desulfurizer for removing sulfur components contained in the fuel gas, and the desulfurizer is connected to the housing housing or the heat exchanger and the combustion exhaust gas discharge flow path. It is characterized by being arranged in a space between.

  Further, in the solid oxide fuel cell system according to claim 2 of the present invention, the combustion exhaust gas discharge flow path is provided with an area expanding portion for increasing the contact or proximity area with the desulfurizer. It is characterized by.

  Further, in the solid oxide fuel cell system according to claim 3 of the present invention, the area expanding portion of the combustion exhaust gas discharge flow path is a flow path expanding housing or combustion that expands the combustion exhaust gas discharge flow path. It is characterized by comprising a plurality of branch exhaust passages for increasing the exhaust gas passages.

  In the solid oxide fuel cell system according to claim 4 of the present invention, a heat insulating material is interposed between the housing and the desulfurizer, and the combustion exhaust gas discharge channel, the desulfurizer, Insulating material is not interposed between the two.

Further, in the solid oxide fuel cell system according to claim 5 of the present invention, the combustion exhaust gas discharge flow path is provided at an upper part of the housing housing, an upper part of the heat exchanger or an upper side of the heat exchanger. A horizontal flow path portion through which combustion exhaust gas flows in a horizontal direction from the projecting housing, and a flow-down flow path portion that flows downward on the downstream side of the horizontal flow path portion, and the desulfurizer includes the housing housing or It is arranged in a space between the heat exchanger and the downstream flow path portion of the combustion exhaust gas discharge flow path.

  In the solid oxide fuel cell system according to claim 6 of the present invention, the desulfurizer includes a container housing in which a desulfurizing agent is accommodated, and a fuel gas containing a sulfur component flows into the container housing. And an outflow part from which the fuel gas from which the sulfur component has been removed flows out. The inflow part and the outflow part are arranged in contact with or in close proximity to each other. Heat exchange is performed with the fuel gas flowing through the section.

According to the solid oxide fuel cell system of the first aspect of the present invention, the desulfurizer disposed in the fuel gas supply channel is a housing (or heat exchanger) in which a fuel cell stack or the like is accommodated. ) and the fuel exhaust gas from the fuel cell stack is disposed in the space between the combustion exhaust gas discharge flow path is discharged from the receiving housing on one side of the desulfurizer (or heat exchanger) The heat from the combustion exhaust gas discharge passage (combustion exhaust gas flowing therethrough) is transmitted to the other side, so that the desulfurization agent in the desulfurizer can be maintained at a substantially uniform temperature. Can be maintained in a desired temperature range (for example, a temperature range of 150 to 300 ° C.), and as a result, high desulfurization performance can be obtained, and sulfur components contained in the fuel gas can be stably removed over a long period of time. It is possible.

  Further, according to the solid oxide fuel cell system according to claim 2 of the present invention, since the area expanding portion is provided in a part of the combustion exhaust gas discharge flow path, the desulfurizer filled with the desulfurizing agent. As a result, the heat from the combustion exhaust gas discharge passage can be effectively transferred to the desulfurization agent.

  In the solid oxide fuel cell system according to claim 3 of the present invention, the area expansion portion of the combustion exhaust gas discharge flow path is constituted by a flow path expansion housing or a plurality of branch discharge flow paths. Therefore, the area enlarged portion can be formed with a simple configuration.

  In the solid oxide fuel cell system according to claim 4 of the present invention, since the heat insulating material is interposed between the storage housing and the desulfurizer, heat transfer from the storage housing side is prevented. In addition, since no heat insulating material is interposed between the combustion exhaust gas discharge flow path and the desulfurizer, heat transfer from the combustion exhaust gas discharge flow path side is transmitted as it is. The temperature of the desulfurizing agent can be maintained in a more uniform temperature state.

In the solid oxide fuel cell system according to claim 5 of the present invention, the combustion exhaust gas discharge flow path protrudes above the housing (or above the heat exchanger or above the heat exchanger). Since it has a horizontal flow path portion that flows in a horizontal direction from the protruding housing ) and a downstream flow path portion that flows downward on the downstream side of this horizontal flow path portion, the flow of combustion exhaust gas becomes smooth, By disposing the desulfurizer in the space between the downstream flow path portion and the housing (or heat exchanger), a large desulfurizer can be disposed as required with a simple structure.

  In the solid oxide fuel cell system according to claim 6 of the present invention, the inflow portion and the outflow portion provided in the container housing of the desulfurizer are arranged in contact with or close to each other. Heat exchange is performed between the fuel gas flowing through the fuel gas (fuel gas containing sulfur component) and the fuel gas flowing through the outflow portion (fuel gas from which the sulfur component has been removed), and the fuel gas flowing through the inflow portion (that is, the desulfurizing agent) The fuel gas flowing in the gas can be heated.

1 is a perspective view schematically illustrating a first embodiment of a solid oxide fuel cell system according to the present invention. FIG. FIG. 2 is a cross-sectional view of the fuel cell system of FIG. Sectional drawing which looked at the fuel cell system of FIG. 1 from diagonally upward. The perspective view which shows the fuel cell stack of the fuel cell system of FIG. 1, and the structure relevant to it seeing from the front side. The perspective view which shows the fuel cell stack of FIG. 4 and the structure relevant to this seeing from the back side. Sectional drawing which shows simply the desulfurizer in the fuel cell system of FIG. The perspective view which shows 2nd Embodiment of the solid oxide fuel cell system according to this invention simply. The perspective view which shows 3rd Embodiment of the solid oxide fuel cell system according to this invention simply. The system diagram which shows simply 4th Embodiment of the solid oxide fuel cell system according to this invention.

  Hereinafter, various embodiments of a solid oxide fuel cell system according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
First, the solid oxide fuel cell system according to the first embodiment will be described with reference to FIGS. 1 to 5, the fuel cell system according to the first embodiment includes a stack assembly 4 composed of a plurality (four in the illustrated embodiment) of stack units 2 (particularly, FIG. 4). And FIG. 5). The plurality of stack units 2 have substantially the same configuration, and one of them will be described below.

  Referring mainly to FIGS. 4 and 5, the illustrated stack unit 2 (2a, 2b) includes two fuel cell stacks 6 in which solid oxide fuel cells are stacked, and these two fuel cells. A cell stack 6 is attached to the upper surface of the fuel header 8. In such a solid oxide fuel cell, for example, zirconia doped with yttria is used as a solid electrolyte that conducts oxygen ions, and a fuel electrode for oxidizing a reformed fuel gas on one side of the solid electrolyte ( (For example, formed from nickel in a metallic state), an air electrode for reducing oxygen in the air is provided on the other side, and a fuel cell stack 6 is configured by stacking a large number of such fuel cells. The In this embodiment, the reformed fuel gas supplied to the fuel header 8 as described later is supplied to the fuel electrode side of a large number of fuel cells of the pair of fuel cell stacks 6 through the fuel header 8, Air as an oxidant flows to the fuel header 8 side through the periphery of the fuel cell stack 6 of the stack unit 2 and is fed from the lower end of the fuel cell stack 6 to the air electrode side.

  In this fuel cell system, a reformer 10 for reforming fuel gas is provided upstream of the stack assembly 4. In this embodiment, a pair of stack units 2a are arranged on the left side in FIG. 4 (right side in FIG. 5), and a pair of stack units 2b are opposed to these stack units 2a on the right side in FIG. 4 (left side in FIG. 5). The reformer 10 is provided with reforming chamber portions 12 (12a, 12b) disposed corresponding to the stack units 2 (2a, 2b). A combustion chamber 14 is provided on the downstream side of the fuel cell stack 6 of the stack unit 2 (2a, 2b), and in this embodiment, at the upper end portion or immediately above the fuel cell stack 6, and the reforming chamber 14 is reformed above the combustion chamber 14. A reforming chamber 12 (12a, 12b) of the vessel 10 is disposed. Each reforming chamber 12 (12a, 12b) has an elongated U-shape, and each reforming chamber 12 (12a, 12b) is filled with a reforming catalyst (not shown). (12a, 12b) is heated by the combustion exhaust gas from the corresponding combustion chamber.

  A vaporizer 16 for vaporizing reforming water is disposed upstream of the reformer 10. In this embodiment, the vaporizer 16 is located in a central region (a horizontal central region in FIGS. 4 and 5) surrounded by the pair of left stack units 2a in FIG. 4 and the pair of right stack units 2b in FIG. By being arranged and configured in this way, the heat generated in the plurality of stack units 2 (2a, 2b) can be used for vaporization of the reforming water, and the vaporizer 16 can be kept at a high temperature. Can do.

  A hydrocarbon-based fuel gas (for example, city gas, LP gas, etc.) is used as the fuel gas, and a hydrocarbon-based fuel gas from a fuel gas supply source 18 (for example, a buried pipe, a gas tank, etc.) is used as the fuel gas supply channel 20. To the vaporizer 16. The fuel gas supply channel 20 is provided with a fuel gas pump 22 (which constitutes combustion gas supply means) for supplying fuel gas and a desulfurizer 24 for removing sulfur components in the fuel gas. The fuel gas from which the sulfur component is removed at 24 is supplied to the vaporizer 16. The desulfurizer 24 will be described later.

  Further, reforming water (for example, pure water) from the reforming water supply source 26 (for example, a water tank) is supplied to the vaporizer 16 through the reforming water supply channel 28. The reforming water supply channel 28 is provided with a water pump 30 (constituting reforming water supply means) for supplying reforming water.

  In this embodiment, as shown in FIG. 4, a double tube 32 is connected to the vaporizer 16. The double pipe 32 has an outer pipe 34 and an inner pipe 36, and the reformed water from the reformed water supply flow path 28 is fed through the inner space of the inner pipe 36 of the double pipe 32 to supply fuel gas. The fuel gas from the flow path 20 is fed through the annular space between the inner pipe 36 and the outer pipe 34 of the double pipe 32.

  The illustrated carburetor 16 includes a vaporization housing 37 that defines a vaporization chamber 35, and a device housing 38 is provided so as to surround the vaporization housing 37. An exhaust gas flow path is provided between the device housing 38 and the vaporization housing 37. 41 is defined. The apparatus housing 38 is provided with inflow openings 40 corresponding to the stack units 2a and 2b (only the inflow openings corresponding to the pair of stack units 2b are shown), and the double pipe 32 includes the apparatus housing 38 and the vaporization housing 37. And extends into the vaporizing chamber 35. With this configuration, the combustion exhaust gas from the combustion chambers 14 of the plurality of stack units 2a, 2b flows around the reforming chamber portions 12a, 12b of the reformer 10, and then passes through these inflow openings 40. It flows into the exhaust gas passage 41 of the vaporizer 16 and is discharged from the passage member 42 through the exhaust gas passage 41 as will be described later. Then, using the heat of the exhaust gas flowing in this manner, the reformed water supplied to the vaporizing chamber 35 of the vaporizing housing is vaporized to become water vapor, and the fuel gas supplied to the vaporizing chamber 35 is heated, and this Steam and fuel gas are fed to the reformer 10.

  The vaporizer 16 is provided with outflow portions 56 (56a, 56b) corresponding to the reforming chamber portions 12a, 12b of the reformer 10, respectively. 4, an outflow portion 56a is provided corresponding to the left stack unit 2a (right side in FIG. 5), and one end portion of the outflow portion 56a is connected to the device housing 38, the exhaust gas passage 41 and the vaporization housing of the carburetor 16. 37 and communicates with the inside of the vaporizing chamber 35, and the other end thereof is connected to the corresponding reforming chamber 12 a of the reformer 10. Also, an outflow portion 56b is provided corresponding to the stack unit 2b on the right side (left side in FIG. 5) in FIG. 4, and one end portion of the outflow portion 56b is connected to the device housing 38 of the carburetor 16, the exhaust gas passage 41, and the like. The vaporization housing 37 passes through and communicates with the vaporization chamber 35, and the other end thereof is connected to the corresponding reforming chamber portion 12 b of the reformer 10. With this configuration, the fuel gas and water vapor uniformly mixed in the vaporizing chamber 35 of the vaporizer 16 are supplied to the reforming chamber portions 12a and 12b of the reformer 10 through the outflow portions 56a and 56b. Is done.

  In this fuel cell system, a mixing housing 58 is further provided between the reformer 10 (that is, the reforming chamber portions 12a and 12b) and the stack assembly 4 (that is, the plurality of stack units 2a and 2b). ing. The mixing housing 58 is disposed below the vaporizer 16 (that is, a central region surrounded by the pair of stack units 2a and the pair of stack units 2b). In this embodiment, the mixing housing 58 is elongated in the front-rear direction (the direction from the lower left to the upper right in FIG. 4) and extends from the front end of the front stack units 2a and 2b to the rear end of the rear stack units 2a and 2b. Yes.

  Outlet connection portions 60 a and 60 b are provided in the reforming chamber portions 12 a and 12 b of the reformer 10, and the outflow connection portions 60 a and 60 b are connected to the front and rear portions of the mixing housing 58 via a T-shaped connection pipe 62. It is connected to the. Further, connecting pipes 64 are provided at the four corners of the mixing housing 58, and one of the front connecting pipes 64 of the mixing housing 58 is connected to the front right corner of the fuel header 8 of the left front stack unit 2a in FIG. The other of the front connection pipe 64 is connected to the front left corner of the fuel header 8 of the right front stack unit 2b in FIG. 4 (see FIG. 4). One of the connection pipes 64 on the rear side of the mixing housing 58 is connected to the rear right corner of the fuel header 8 of the stack unit 2a on the left rear side in FIG. 4, and the other connection pipe 64 on the rear side is connected to the right rear side. It is connected to the rear left corner of the fuel header 8 of the stack unit 2b on the side (see also FIG. 5).

  Since it is configured in this manner, the reformed fuel gas steam-reformed in the reforming chambers 12a and 12b on the front side of the reformer 10 is mixed through the outflow connection parts 60a and 60b and the connecting connection pipe 62. The reformed fuel gas fed into the front part of the housing 58 and steam reformed in the reforming chambers 12a and 12b on the rear side is mixed through the outflow connection parts 60a and 60b and the connecting connection pipe 62. The reformed fuel gas fed into the rear portion and thus flowing in is mixed in the mixing housing 58. Then, the reformed fuel gas mixed in the mixing housing 58 is supplied to the fuel header 8 of the corresponding stack unit 2 (2a, 2b) via each connection pipe 64, and these members including the mixing housing 58 are Then, the reformed fuel gas feed passage for feeding the reformed fuel gas to the stack assembly 4 is configured.

  In this embodiment, as shown in FIGS. 1 to 3, the stack assembly 4 (a plurality of stack units 2 a and 2 b), the combustion chamber 14, and the reformer 10 (reforming chamber portions 12 a and 12 b) are contained in a housing 72. Is housed in. The housing housing 72 is made of a heat-resistant metal, the inner surface thereof is covered with a heat insulating material, and the inside of the housing housing 72 is kept at a high temperature.

  An air housing 74 is disposed above the housing housing 72, and a heat exchanger 76 is disposed above the air housing 74. The end wall 78 of the heat exchanger 76 (the right end wall in FIGS. 1 to 3) is provided with a first inflow pipe portion 80, and an air supply flow path 81 is connected to the first inflow pipe portion 80, Air (oxidant) from the blower fan 82 flows into the heat exchanger 76 from the first inflow pipe portion 80 through the air supply flow path 81.

  A first outflow portion (not shown) of the heat exchanger 76 is communicated with the air housing 74, and the air that has flowed through the heat exchanger 76 flows into the air housing 74 from the first outflow portion, and from the air housing 74. It flows to the fuel header 8 side through the periphery of the fuel cell stack 6 of each stack unit 2 (2a, 2b) and is fed to the air electrode side.

  Further, the flow path member 42 of the vaporizer 16 passes through the air housing 74 and is connected to a second inflow portion (not shown) of the heat exchanger 76. Further, a protruding housing 86 is provided on the upper wall 84 of the heat exchanger 76, and a second outflow portion 90 is provided on an end wall 88 (the right end wall in FIGS. 1 to 3) of the protruding housing 86, The flow path member 42 of the carburetor 16, the heat exchanger 76, the second inflow portion thereof, the second outflow portion 90 thereof, etc. constitute a combustion exhaust gas discharge passage 92 for discharging the combustion exhaust gas to the outside.

  With this configuration, the combustion exhaust gas from the flow path member 42 of the carburetor 16 flows into the heat exchanger 76 through the second inflow portion, and while flowing through the heat exchanger 76, Heat exchange is performed with the air flowing in from the first inflow portion 80, and the air heated by the heat exchange flows out from the first outflow portion, while the combustion exhaust gas flows to the protruding housing 86 through the heat exchanger 76. The second outflow portion 90 is discharged to the outside through the combustion exhaust gas discharge passage 92 as will be described later.

  This solid oxide fuel cell system is further configured as follows. Further explanation with reference to FIG. 1 to FIG. 3 is for increasing the flow passage area (in other words, increasing the contact or proximity area with the desulfurizer 24) in a part of the combustion exhaust gas discharge flow passage 92. An area enlarging portion 96 is provided, the area enlarging portion 96 is constituted by a flow path expanding housing 98, an inflow connection portion 100 is provided at the upper end portion of the flow path expanding housing 98, and an outflow connection portion 102 is provided at the lower end portion thereof. Is provided. The flow path expanding housing 98 is constituted by a hollow rectangular box-shaped member, and a flow path space is defined therein.

  In this embodiment, the flow path expanding housing 98 is disposed to face the end wall 104 (the right end wall in FIGS. 1 to 3) of the housing housing 72, and the end wall 104 and the flow path expanding housing 98 A desulfurizer 24 is disposed therebetween. In such a configuration, the combustion exhaust gas flows in the horizontal direction from the second outflow portion 90 (functioning as a horizontal flow path portion) of the protruding housing 86 on the upper side of the heat exchanger 76, and then flows into the inflow connection portion 100 and the flow path. The enlarged housing 98 and the outflow connection portion 102 (which function as a flow-down flow path portion) flow downward as indicated by an arrow 106, and by configuring in this way, the flow of the combustion exhaust gas becomes smooth and solid. It is possible to reduce the size of the oxide fuel cell system while suppressing the height thereof.

  Next, the desulfurizer 24 will be described mainly with reference to FIG. 6. The illustrated desulfurizer 24 includes a box-shaped container housing 108, and the container housing 108 is formed to have substantially the same size as the flow path expanding housing 98. Has been. An inflow channel 110 is provided at the bottom of the container housing 108, an outflow channel 112 is provided above the inflow channel 110, and a filling space 115 is further provided above the outflow channel 112. The filling space 115 is provided in most part except for the lower part of the container housing 108, and in the filling space 115, a plurality of partition walls 116 are arranged in a staggered manner, and thus the partition walls 116 are formed. By providing, the length of the flow path through which the fuel gas flows can be lengthened, and the filling space 115 is filled with the desulfurizing agent 118. As this desulfurizing agent, a copper-zinc-based one (for example, one disclosed in JP-A-10-243336) can be conveniently used.

  In the desulfurizer 24, the inflow channel 110 and the outflow channel 112 extend in contact with each other. An inflow pipe 114 (which constitutes a part of the fuel gas supply flow path 20) is connected to the inlet of the inflow flow path 110, and the fuel gas from the fuel gas supply source 18 passes through the inflow pipe 114 as indicated by an arrow 118. Then, the sulfur component in the fuel gas is removed by the desulfurizing agent while flowing in the filling space 115 through the inflow channel 110. An outflow pipe 120 is connected to the outflow port of the outflow channel 112, and the fuel gas from which the sulfur component has been removed flows out of the outflow tube 120 through the outflow channel 112 as shown by an arrow 122, and the fuel gas supply flow It flows downstream through the passage 20 and is fed from the double pipe 32 to the vaporizer 16. At this time, since the inflow channel 110 and the outflow channel 112 are in contact with each other, the fuel gas (including the sulfur component) that flows through the inflow channel 110 and the fuel gas (the sulfur component that flows through the outflow channel 112). Heat exchange is performed between the fuel gas and the fuel gas heated by the heat exchange. Even if the inflow channel 110 and the outflow channel 112 are arranged close to each other, the same effect as described above can be achieved.

  In this solid oxide fuel cell system, the operating temperature of each fuel cell stack 6 is as high as around 700 ° C., whereby the temperature of the peripheral side wall including the end wall 104 of the housing 72 is kept at 300 ° C. or higher. Be drunk. The temperature of the combustion exhaust gas flowing from the stack assembly 4 through the heat exchanger 76 through the combustion exhaust gas discharge passage 92 (in other words, the combustion exhaust gas flowing through the passage expansion housing 98) is 200 to 300 ° C. Therefore, a sufficient space having a temperature range of 150 to 300 ° C. can be generated between the end wall 104 of the housing housing 72 and the flow passage expanding housing 98. The desulfurizer 24 is disposed using the space. By arranging the desulfurizer 24 in this way, the entire desulfurizer 24 (that is, the desulfurizing agent filled therein) is obtained in a temperature range of 150 to 300 ° C. (that is, the copper-zinc-based desulfurizing agent has high desulfurizing performance. Temperature range), and as a result, the sulfur component in the fuel gas can be removed while maintaining high desulfurization characteristics.

  In order to equalize the heat transmitted from the housing housing 72 and the heat transmitted from the flow path expanding housing 98, heat is transferred between the end wall 104 of the housing housing 72 and the desulfurizer 24 on the housing housing 72 side. A heat insulating material (not shown) for adjusting the transmission is interposed, and the wall surface of the flow path expanding housing 98 is brought into direct contact with the desulfurization agent on the area expanding portion 96 side (that is, no heat insulating material is interposed). This is preferable, and by doing so, the entire desulfurizer 24 can be maintained at a substantially uniform temperature state.

  In this embodiment, a protruding housing 86 is provided above the heat exchanger 76, and the second outflow portion 90 (horizontal flow path portion) is provided in the protruding housing 86. However, the protruding housing 86 is omitted, The two outflow portions 90 may be provided directly on the top of the heat exchanger 86. Further, when the heat exchanger 76 itself is omitted, the combustion exhaust gas from the stack assembly 4 is exhausted from the housing housing 72, so that this outflow part (which constitutes a part of the combustion exhaust gas discharge flow path 92) is provided. It can be provided on the upper part of the housing 72.

[Second Embodiment]
Next, a solid oxide fuel cell system according to a second embodiment will be described with reference to FIG. In the second embodiment, the desulfurizer is disposed between the heat exchanger and the flow path expanding housing of the combustion exhaust gas discharge flow path. In the following embodiments, members substantially the same as those in the first embodiment described above are given the same reference numerals, and descriptions thereof are omitted.

  In FIG. 7, in the second embodiment, an air housing 74 is disposed above a housing 72 in which a stack assembly (not shown) and a reformer (reforming chamber) (not shown) are housed. The heat exchanger 76 is disposed above the air housing 74. In addition, a protruding housing 86 is provided above the end of the heat exchanger 76, and a flow path expanding housing 98A is disposed from the protruding housing 86 so as to cover the heat exchanger 76. 98A extends in the horizontal direction above the heat exchanger 76, and a space is formed between the flow passage expanding housing 98A and the heat exchanger 76, and the desulfurizer 24A is disposed in the space. Other configurations of the solid oxide fuel cell system are substantially the same as those of the first embodiment described above.

  In this second embodiment, combustion exhaust gas from a stack assembly (not shown) flows through the heat exchanger 76 to the protruding housing 86 and then through the channel expansion housing 98A as indicated by the arrow 134 from the exhaust 132. The exhaust gas is discharged to the outside through the combustion exhaust gas discharge channel. Air as an oxidizing material flows from the first inflow pipe portion 80 into the heat exchanger 76 as shown by an arrow 136, flows through the heat exchanger 76 to the air housing 74, and passes through the air housing 74 to form a stack aggregate. (Not shown) is fed to the air electrode side. At this time, as described above, heat exchange is performed between the combustion exhaust gas flowing through the heat exchanger 76 and the air, and the heated air is supplied to the air housing 74.

  In the second embodiment, heat from the heat exchanger 76 is transmitted on one side (the lower surface side in FIG. 7) of the desulfurizer 24A, and from the flow path expanding housing 98A on the other side (the upper surface side in FIG. 7). Heat is transferred, and the space between the heat exchanger 76 and the flow passage expanding housing 98A is in the temperature range of about 150 to 300 ° C. (that is, the temperature at which the copper-zinc-based desulfurizing agent can exhibit high desulfurization performance. As a result, the sulfur component in the fuel gas can be removed while maintaining high desulfurization characteristics even if the desulfurizer 24A is disposed in such a space.

  As understood from the above description, since the combustion exhaust gas after flowing through the heat exchanger 76 flows into the flow passage expanding housing 98A, the temperature on the heat exchanger 76 side is higher, and accordingly, the desulfurizer 24A. A small space is provided between the heat exchanger 76 and a heat insulating material if necessary, and a space is not provided between the desulfurizer 24A and the flow passage expanding housing 98A. It is desirable to make it contact.

[Third Embodiment]
Next, a solid oxide fuel cell system according to a third embodiment will be described with reference to FIG. In 3rd Embodiment, the heat exchanger is provided in the side surface side (front side surface side in FIG. 8) of a storage housing, and the desulfurizer and the flow-path expansion housing are provided in relation to this heat exchanger.

  In FIG. 8, in the third embodiment, an air housing 74B is provided on the upper side of the housing housing 72B. In addition, a heat exchanger 76B is disposed on the front side (front side surface) of the housing housing 72B (not shown, but the stack assembly and the reformer are housed), and one end of the heat exchanger 76B. A protruding housing 86B is provided at the portion, and a flow path expanding housing 98B is disposed so as to cover the front side of the heat exchanger 76B from the protruding housing 86B. The flow path expanding housing 98B is disposed on the front side of the heat exchanger 76B. It extends in the horizontal direction, a space is formed between the flow path expanding housing 98B and the heat exchanger 76B, and the desulfurizer 24B is disposed in this space. Other configurations of the solid oxide fuel cell system are substantially the same as those of the first embodiment described above.

  In the third embodiment, the combustion exhaust gas from the stack assembly (not shown) flows out through the outflow pipe 142 provided in the end wall 104 of the container housing 72B, and passes through the combustion exhaust gas discharge passage 92B. After flowing from the inflow pipe 144 to the heat exchanger 76B, through the heat exchanger 76B, it flows through the protruding housing 86B and the flow passage expanding housing 98B, and then from the outflow pipe 146 through the combustion exhaust gas discharge flow path 92B as indicated by an arrow 148. It is discharged outside. Air as an oxidant flows from the inflow pipe 152 into the heat exchanger 76B as indicated by an arrow 150, and after flowing through the heat exchanger 76B, from the outflow pipe 154 through the air supply channel 156 and the inflow pipe 158. The air flows to the air housing 74B and is fed to the air electrode side of the stack assembly (not shown) through the air housing 74B. At this time, as described above, heat exchange is performed between the combustion exhaust gas flowing through the heat exchanger 76B and the air, and the heated air is supplied to the air housing 74B. Further, fuel gas from a fuel gas supply source (not shown) flows into the desulfurizer 24B from the inflow pipe 162 as indicated by an arrow 160, and after the sulfur component is removed while flowing through the desulfurizer 24B. The fuel gas is supplied from the double pipe 32 to the vaporizer (not shown) through the fuel gas supply channel 20B.

  Also in the third embodiment, heat from the heat exchanger 76B is transmitted on one side (the back side in FIG. 8) of the desulfurizer 24B, and from the flow path expanding housing 98B on the other side (the front side in FIG. 8). Heat is transferred, and the space between the heat exchanger 76B and the flow passage expanding housing 98B is in a temperature range of about 150 to 300 ° C. (that is, the temperature at which the copper-zinc-based desulfurizing agent can exhibit high desulfurization performance. As a result, the sulfur component in the fuel gas can be removed while maintaining high desulfurization characteristics even with this configuration.

[Fourth Embodiment]
Next, a solid oxide fuel cell system according to a fourth embodiment will be described with reference to FIG. In the fourth embodiment, a part of the reformed fuel gas steam-reformed by the reformer is returned to the fuel gas supply channel.

  In FIG. 9, a pressure adjusting means 172, a fuel gas flow rate detecting means 174, a fuel gas supply means 176, a desulfurizer 24C, and a fuel gas supply flow path 20C for supplying fuel gas from the fuel gas supply source 18 to the reformer 10C The vaporizer 16C is disposed in this order. The pressure adjusting unit 172 adjusts the pressure of the fuel gas supplied from the fuel gas supply source 18. For example, a zero governor can be used as the pressure adjusting unit 172. When the zero governor is used, the pressure of the fuel gas supplied from the fuel gas supply source 18 can be maintained at the atmospheric pressure (that is, from the pressure adjusting unit 172). The pressure of the upstream fuel gas is set to atmospheric pressure).

  Further, the fuel gas flow rate detecting means 174 detects the flow rate of the fuel gas flowing through the fuel gas supply channel 20C. The fuel gas supply means 176 is composed of, for example, a fuel gas pump 178, and the amount of fuel gas supplied through the fuel gas supply channel 20C can be controlled by controlling the rotational speed of the fuel gas pump 178. As the rotational speed increases (or decreases), the amount of fuel gas supplied increases (or decreases). The desulfurizer 24C includes a desulfurizing agent as described above, and removes sulfur components in the fuel gas using the desulfurizing agent. As this desulfurizing agent, for example, a copper-zinc-based one can be used conveniently.

  As described above, the reforming water supply channel 28C is connected to the vaporizer 16C, and the water supply means 180 is disposed in the reforming water supply channel 28C. The water supply means 180 is composed of, for example, a water pump 182, and the amount of reforming water supplied through the reforming water supply channel 28 </ b> C can be controlled by controlling the rotation speed of the water pump 182. When the rotational speed increases (or decreases), the supply amount of reforming water increases (or decreases). Fuel gas is supplied to the vaporizer 16C through the fuel gas supply flow path 20C, and reformed water from the reformed water supply source 26 is supplied through the reformed water supply flow path 28C to the vaporizer 16C. Then, the reformed water is vaporized and the fuel gas is heated, and the vaporized water vapor and the heated fuel gas are supplied to the reformer 10C. Then, the reformed fuel gas steam-reformed by the reformer 10 C is sent to the fuel header 8 of the fuel cell stack 6 through the reformed fuel gas feed channel 184, and the fuel electrode is passed through the fuel header 8. To the side. In addition, air from the blower fan 82 is supplied to the air electrode side of the fuel cell stack 6 through the air supply passage 81.

  In the fourth embodiment, a bypass passage 186 is provided so that part of the reformed fuel gas returns to the fuel gas supply passage 20C. One end side of the bypass flow path 186 is connected to the reformed fuel gas supply flow path 184, and the other end side is connected to the fuel gas supply flow path 20C, specifically, the pressure adjusting means 172 (for example, zero governor) and the fuel gas supply. It is connected to a portion between the means 176 (for example, the fuel gas pump 178).

  Since it is configured in this way, a part of the reformed fuel gas steam reformed in the reformer 10C is returned to the fuel gas supply channel 20C through the bypass channel 186 and mixed with the fuel gas, The mixed fuel gas is fed to the desulfurizer 24C through the fuel gas supply channel 20C. Accordingly, the fuel gas supplied to the desulfurizer 24C contains a small amount of reformed fuel gas (particularly, hydrogen generated by steam reforming), and as a result, a desulfurizing agent (for example, a copper-zinc based material) in the desulfurizer 24C. The desulfurization agent) exhibits high desulfurization performance, and sulfur components in the fuel gas can be removed with high desulfurization performance. Further, since the other end side of the bypass flow path 186 is connected to a portion of the fuel gas supply flow path 20C between the fuel gas pump 178 and the pressure adjusting means 172, the fuel gas pump 178 is activated to supply the fuel gas. Then, the pressure at this portion (the portion to which the bypass flow path 186 is connected) is somewhat lowered to generate a negative pressure state, and flows through the reformed fuel gas supply flow path 184 using the generated negative pressure state. A part of the reformed fuel gas can be returned to the fuel gas supply flow path 20C through the bypass flow path 186, and thus the desulfurization performance of the desulfurizer 24C is high with a simple configuration in which the bypass flow path 186 is provided. Can be removed to remove the sulfur component.

  The technical matter of the fourth embodiment (that is, the technology for returning part of the reformed fuel gas to the fuel gas supply flow path) can be used alone, but the technology of the first to third embodiments. Higher desulfurization performance can be exhibited by using in combination with the target matter (that is, the technology of arranging the desulfurizer in a space having a temperature range of 150 to 300 ° C.).

Although various embodiments of the solid oxide fuel cell system according to the present invention have been described above, the present invention is not limited to such embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. Is possible,
For example, in the illustrated embodiment, two stack units 2a are disposed on one side, and two stack units 2b are disposed on the other side so as to face the two stack units 2a. One or three or more stack units may be arranged, and for example, one or three or more stack units may be arranged on the other side (the other side is opposite to the one on one side. Need not be installed).

  Further, for example, in the illustrated embodiment, each stack unit 2a, 2b is composed of two fuel cell stacks 6, but may be composed of three or more fuel cell stacks 6, or Instead of being configured in such a stack unit, the present invention can be similarly applied to a fuel cell stack 6 provided with one or more fuel cell stacks 6.

  Further, for example, in the illustrated embodiment, the area expanding portion 96 of the combustion exhaust gas discharge flow path 92 is configured from the flow path expanding housing 98, but is not limited to such a configuration, and a plurality of the area expanding portions are included. In this case, the combustion exhaust gas flowing through the combustion exhaust gas discharge flow path branches through the plurality of branch discharge flow paths, and the combustion flows through the plurality of branch discharge flow paths. Heat from the exhaust gas is transmitted to the desulfurizer 24.

2, 2a, 2b Stack unit
4 Stack assembly 6 Fuel cell stack 10 Reformer 16 Vaporizer 24, 24A, 24B, 24C Desulfurizer 72 Housing housing 74 Air housing 76 Heat exchanger 92, 92B Combustion exhaust gas discharge flow path 96 Area expansion part 98, 98A, 98B Channel expansion housing

Claims (6)

Fuel gas supply means for supplying fuel gas through the fuel gas supply flow path, a reformer for steam reforming the fuel gas from the fuel gas supply means, and reforming reformed by the reformer Provided on the downstream side of the fuel cell stack for burning a fuel cell stack composed of a plurality of fuel cells that generate power by oxidation and reduction of fuel gas and oxidant, and surplus fuel gas that does not contribute to power generation A combustion chamber, an air supply means for supplying air as an oxidant to the fuel cell stack through an air supply channel, and combustion for exhausting combustion exhaust gas from the fuel cell stack and the combustion chamber A heat exchanger provided in the exhaust gas discharge flow path; and a housing for housing the reformer, the fuel cell stack, and the combustion chamber, the heat exchanger comprising: Heat exchange is performed between the combustion exhaust gas flowing through the combustion exhaust gas discharge passage and the air flowing through the air supply passage, and the air heated by the heat exchanger is supplied to the fuel cell stack. A solid oxide fuel cell system comprising:
The fuel gas supply flow path is provided with a desulfurizer for removing sulfur components contained in the fuel gas, and the desulfurizer is connected to the housing housing or the heat exchanger and the combustion exhaust gas discharge flow path. A solid oxide fuel cell system, wherein the solid oxide fuel cell system is disposed in a space between the two .   2. The solid oxide fuel cell system according to claim 1, wherein the combustion exhaust gas discharge passage is provided with an area enlargement portion for increasing a contact area or a proximity area with the desulfurizer. .   The area expansion portion of the combustion exhaust gas discharge flow path is configured by a flow path expansion housing that expands the combustion exhaust gas discharge flow path or a plurality of branch discharge flow paths that increase the flow path of combustion exhaust gas. The solid oxide fuel cell system according to claim 2, wherein the fuel cell system is a solid oxide fuel cell system.   The heat insulating material is interposed between the housing housing and the desulfurizer, and the heat insulating material is not interposed between the combustion exhaust gas discharge passage and the desulfurizer. 4. The solid oxide fuel cell system according to any one of 3 above. The combustion exhaust gas discharge passage includes a horizontal passage portion through which combustion exhaust gas flows in a horizontal direction from a protruding housing provided on an upper portion of the housing housing, an upper portion of the heat exchanger or an upper side of the heat exchanger , A downstream flow channel portion that flows downward on the downstream side of the horizontal flow channel portion, and the desulfurizer includes the housing housing or the heat exchanger and the downstream flow channel portion of the combustion exhaust gas discharge channel. The solid oxide fuel cell system according to any one of claims 1 to 4, wherein the solid oxide fuel cell system is disposed in a space therebetween.   The desulfurizer includes a container housing containing a desulfurizing agent, and the container housing is provided with an inflow portion into which a fuel gas containing a sulfur component flows in and an outflow portion from which the fuel gas from which the sulfur component has been removed flows out. The inflow portion and the outflow portion are arranged in contact with or close to each other, and heat exchange is performed between the fuel gas flowing through the inflow portion and the fuel gas flowing through the outflow portion. Item 6. The solid oxide fuel cell system according to any one of Items 1 to 5.

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