Fuel cell system

Abstract

By sufficiently suppressing heat dissipation outside the case, power generation efficiency is further improved. [Solution] The fuel cell system comprises a fuel cell, a combustion section, a plurality of heat exchange sections, and an insulated case housing them. Each of the plurality of heat exchange sections has a low-temperature gas flow path through which a low-temperature gas, which is the fuel gas or oxidizer gas supplied to the fuel cell, flows, and a high-temperature gas flow path through which an off-gas discharged from the fuel cell or a high-temperature gas, which is the combustion exhaust gas discharged from the combustion section, flows, and heat exchange is performed between the low-temperature gas and the high-temperature gas. Furthermore, at least the fuel cell, the combustion section, and the plurality of heat exchange sections are arranged such that temperature zones of a first layer, a second layer, and a third layer are formed sequentially from the center outward in the internal space of the case, the fuel cell is located in the first layer, the combustion section is located in the first or second layer, one or more of the plurality of heat exchange sections are located in the second layer, and one or more of the other heat exchange sections are located in the third layer.

Description

Technical Field

[0004] , , , , , ,

[0003] , , ,

[0001] This specification discloses a fuel cell system.

Background Art

[0002] Conventionally, a fuel cell that generates electricity using reformed gas and air for power generation, a combustor that burns both the off-gas of the reformed gas discharged from the fuel cell and the off-gas of the air for power generation, and a combustion exhaust gas path through which the combustion exhaust gas generated in the combustor flows and a first air supply path through which the air for power generation flows are provided. A first air heat exchanger that exchanges heat between the combustion exhaust gas and the air for power generation, a fuel cell housing that houses the fuel cell and through which the off-gas of the air for power generation discharged from the fuel cell flows, and a second air supply path that supplies the air for power generation that has flowed through the first air supply path to the fuel cell. A second air heat exchanger that exchanges heat between the off-gas of the air for power generation flowing through the fuel cell housing and the air for power generation flowing through the second air supply path, and a housing that houses each member are provided. A fuel cell device has been proposed in which the first air supply path and the second air supply path are arranged so as to cover the entire member housed inside the housing (see, for example, Patent Document 1). According to this fuel cell device, it is possible to suppress the amount of heat radiated to the outside and to facilitate the temperature control of the air for power generation and each part of the fuel cell device. <00OO010>

Prior Art Documents

Patent Documents

[0003] ​​​​​​​​​​​​​

[0005] The primary purpose of this disclosure is to further improve power generation efficiency by sufficiently suppressing heat dissipation outside the case. [Means for solving the problem]

[0006] This disclosure employs the following means to achieve the primary objectives described above.

[0007] In other words, the first fuel cell system of the present disclosure comprises a fuel cell that generates electricity by the reaction of a fuel gas supplied to a fuel electrode and an oxidizer gas supplied to an oxidizer electrode, a combustion section that burns a combustible gas, a low-temperature gas passage through which a low-temperature gas, which is the fuel gas or oxidizer gas supplied to the fuel cell, flows, and a high-temperature gas passage through which an off-gas discharged from the fuel cell or a high-temperature gas, which is the combustion exhaust gas discharged from the combustion section, flows, and a plurality of heat exchange sections that exchange heat between the low-temperature gas flowing through the low-temperature gas passage and the high-temperature gas flowing through the high-temperature gas passage, and a heat-insulating structure, and the fuel cell and the The gist of the invention is a fuel cell system comprising a case housing a combustion section and a plurality of heat exchange sections, wherein at least the fuel cell, the combustion section, and the plurality of heat exchange sections are arranged in layers such that a first layer, a second layer, and a third layer are formed sequentially from the center outward in the internal space of the case, the fuel cell is located in the first layer, the combustion section is located in the first or second layer, one or more of the plurality of heat exchange sections are located in the second layer, and one or more other of the plurality of heat exchange sections are located in the third layer.

[0008] In the first fuel cell system of this disclosure, at least a fuel cell, a combustion section, and a plurality of heat exchange sections are arranged in layers such that a first layer, a second layer, and a third layer of temperature zones are formed sequentially from the center of the case outwards. The fuel cell is placed in the first layer, the combustion section is placed in either the first or second layer, one or more of the plurality of heat exchange sections are placed in the second layer, and one or more other of the plurality of heat exchange sections are placed in the third layer. This allows heat from the high-temperature components, such as the fuel cell and combustion section, located in the center, to be transferred to the components (multiple heat exchange sections) located on the outside, while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the case can be sufficiently suppressed, and power generation efficiency can be further improved.

[0009] Furthermore, the second fuel cell system of this disclosure comprises a fuel cell that generates electricity by the reaction of a fuel gas supplied to a fuel electrode and an oxidizer gas supplied to an oxidizer electrode, a combustion section that burns a combustible gas, a low-temperature gas passage through which a low-temperature gas, which is the fuel gas or oxidizer gas supplied to the fuel cell, flows, and a high-temperature gas passage through which an off-gas discharged from the fuel cell or a high-temperature gas, which is the combustion exhaust gas discharged from the combustion section, are each in different combinations, and a plurality of heat exchange sections that exchange heat between the low-temperature gas flowing through the low-temperature gas passage and the high-temperature gas flowing through the high-temperature gas passage, and thermal insulation A fuel cell system comprising a case housing the fuel cell, the combustion section, and the plurality of heat exchange sections, wherein at least the fuel cell, the combustion section, and the plurality of heat exchange sections are arranged in layers such that a first layer, a second layer, and a third layer are formed sequentially from the center outward in the internal space of the case, the fuel cell and the combustion section are arranged in the first layer, one or more of the plurality of heat exchange sections are arranged in the second layer, and one or more other of the plurality of heat exchange sections are arranged in the third layer.

[0010] In the second fuel cell system of this disclosure, at least a fuel cell, a combustion section, and a plurality of heat exchange sections are arranged in layers such that a first layer, a second layer, and a third layer of temperature zones are formed sequentially from the center of the case outwards. The fuel cell and combustion section are placed in the first layer, one or more of the plurality of heat exchange sections are placed in the second layer, and one or more other of the plurality of heat exchange sections are placed in the third layer. This allows heat from the fuel cell and combustion section, which are high-temperature components located in the center, to be transferred to the components (multiple heat exchange sections) located on the outside, while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the case can be sufficiently suppressed, and power generation efficiency can be further improved.

[0011] The third fuel cell system of this disclosure comprises a fuel cell that generates electricity by the reaction of a fuel gas supplied to a fuel electrode and an oxidizer gas supplied to an oxidizer electrode, a combustion section that burns a combustible gas, a low-temperature gas passage through which a low-temperature gas, which is the fuel gas or oxidizer gas supplied to the fuel cell, flows, and a high-temperature gas passage through which an off-gas discharged from the fuel cell or a high-temperature gas, which is the combustion exhaust gas discharged from the combustion section, each in a different combination, and a plurality of heat exchange sections that exchange heat between the low-temperature gas flowing through the low-temperature gas passage and the high-temperature gas flowing through the high-temperature gas passage, and A fuel cell system comprising a case having thermal properties and housing the fuel cell, the combustion section, and the plurality of heat exchange sections, wherein the combustion cell and the combustion section are arranged in the internal space of the case, the fuel cell is the first layer, and the space between the outer surface of the fuel cell and the inner surface of the case is divided into a second layer and a third layer sequentially from the center of the case outward, the second layer has one or more of the plurality of heat exchange sections, and the third layer has one or more of the plurality of heat exchange sections.

[0012] In the third fuel cell system of this disclosure, the fuel cell, which is arranged in the internal space of the case, is defined as the first layer. The space between the outer surface of the fuel cell and the inner surface of the case is divided into a second layer and a third layer, sequentially from the center of the case outwards. In the second layer, one or more heat exchangers from a plurality of heat exchangers are arranged, and in the third layer, one or more other heat exchangers from a plurality of heat exchangers are arranged. This allows heat from the fuel cell, which is a high-temperature component, to be transferred to the components (multiple heat exchangers) arranged on the outside, while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the case can be sufficiently suppressed, and power generation efficiency can be further improved.

[0013] The fourth fuel cell system of this disclosure is a fuel cell system comprising: a fuel cell that generates electricity by the reaction of a fuel gas supplied to a fuel electrode and an oxidizer gas supplied to an oxidizer electrode; a combustion section that burns a combustible gas; a low-temperature gas passage through which a low-temperature gas, which is the fuel gas or oxidizer gas supplied to the fuel cell, flows; a high-temperature gas passage through which an off-gas discharged from the fuel cell or a high-temperature gas, which is the combustion exhaust gas discharged from the combustion section, flows, each in a different combination; a plurality of heat exchange sections that exchange heat between the low-temperature gas flowing through the low-temperature gas passage and the high-temperature gas flowing through the high-temperature gas passage; and a case that has thermal insulation properties and houses the fuel cell, the combustion section and the plurality of heat exchange sections, wherein the fuel cell and the combustion section are located in the central part of the internal space of the case; one or more of the plurality of heat exchange sections are arranged to cover at least a part of the fuel cell and the combustion section from the outside; and one or more other heat exchange sections are arranged to cover at least a part of the one or more of the plurality of heat exchange sections from the outside.

[0014] In the fourth fuel cell system of this disclosure, the fuel cell and combustion section are arranged in the central part of the internal space of the case, one or more of the multiple heat exchange sections are arranged to cover at least a portion of the fuel cell and combustion section from the outside, and one or more of the other heat exchange sections are arranged to cover at least a portion of one or more of the heat exchange sections from the outside. This makes it possible to transfer heat from the fuel cell and combustion section, which are high-temperature components located in the central part, to the components located on the outside (multiple heat exchange sections) while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the case can be sufficiently suppressed, and power generation efficiency can be further improved. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of the fuel cell system 10 of this embodiment. [Figure 2] This is a schematic diagram of the power generation module 20. [Figure 3] This is an explanatory diagram illustrating the temperature zones of each layer in the power generation module 20. [Figure 4] This is an internal perspective view of the power generation module 20. [Figure 5] This is an internal perspective view of the power generation module 20. [Figure 6] This is an explanatory diagram showing other installation examples of the combustor 22. [Figure 7] This is a schematic diagram of the power generation module 120 according to another embodiment. [Figure 8] This is a schematic diagram of the power generation module 220 according to another embodiment. [Modes for carrying out the invention]

[0016] Next, the forms for implementing this disclosure will be described with reference to the drawings.

[0017] FIG. 1 is a schematic configuration diagram of a fuel cell system 10 according to the present embodiment, and FIG. 2 is a schematic configuration diagram of a power generation module 20. As shown in FIG. 1, the fuel cell system 10 according to the present embodiment includes a power generation module 20 including a fuel cell stack 21, a fuel supply system 40 that supplies fuel gas to the power generation module 20, an air supply system 50 that supplies air to the power generation module 20, and a reflux system 60.

[0018] As shown in FIGS. 1 and 2, in addition to the fuel cell stack 10, the power generation module 20 includes a combustor 22 and first, second, and third heat exchangers 31, 32, and 33, which are housed in a box-shaped module case 39 having heat insulation properties.

[0019] The fuel cell stack 10 includes a plurality of solid oxide type single cells 11 each including a solid electrolyte, a fuel electrode (anode) disposed on one surface side of the solid electrolyte, and an oxidant electrode (cathode) disposed on the other surface side of the solid electrolyte. Since the fuel cell stack 10 operates in a high temperature environment of about 600 to 800°C, the solid electrolyte, fuel electrode, and oxidant electrode are made of a ceramic material. A cermet of a metal such as nickel having a catalytic action and a ceramic is used for the fuel electrode. The fuel cell stack 21 generates power by the reaction of hydrogen contained in the fuel gas supplied to the fuel electrode and oxygen contained in the oxidant gas (air) supplied to the oxidant electrode. Then, the fuel cell stack 21 discharges a fuel off-gas containing unreacted fuel gas and water vapor from the fuel electrode, and discharges an air off-gas containing unreacted oxygen from the oxidant electrode. A temperature sensor (not shown) is installed near the fuel cell stack 21. The temperature sensor detects a temperature (stack temperature) correlated with the temperature of the fuel cell stack 21.

[0020] As shown in FIG. 1, one end of a fuel electrode inlet pipe 21a is connected to the fuel electrode inlet of the fuel cell stack 10, and a fuel supply system 40 is connected to the other end of the fuel electrode inlet pipe 21a. One end of an oxidant electrode inlet pipe 21b is connected to the oxidant electrode inlet of the fuel cell stack 10, and an air supply system 50 is connected to the other end of the oxidant electrode inlet pipe 21b. Also, one end of a fuel electrode outlet pipe 21c is connected to the fuel electrode outlet of the fuel cell stack 10, and a reflux system 60 is connected to the other end of the fuel electrode outlet pipe 21c. One end of an oxidant electrode outlet pipe 21d is connected to the oxidant electrode outlet of the fuel cell stack 10, and a combustor 22 is connected to the other end of the oxidant electrode outlet pipe 21d. In addition to the oxidant electrode outlet pipe 21d, a combustion gas pipe 21e and a combustion exhaust gas pipe 21f are connected to the combustor 22.

[0021] The combustor 22 introduces fuel off-gas (reflux combustion gas) through the combustion gas pipe 21e and air off-gas through the oxidant electrode outlet pipe 21d, and burns these mixed gases. The combustor 22 is provided with an ignition device for igniting the mixed gas and a temperature sensor for detecting the temperature inside the combustor 22.

[0022] The first and third heat exchangers 31 and 33 are flat plate-shaped heat exchangers with meandering flow channels formed inside, and the second heat exchanger 32 is a flat plate-shaped heat exchanger with meandering flow channels formed inside, which bends in a roughly L-shape when viewed from the front. As shown in Figure 2, the first heat exchanger 31 is equipped with a fuel gas flow channel 31a interposed in the fuel electrode inlet pipe 21a and a combustion exhaust gas flow channel 31b interposed in the combustion exhaust gas pipe 21f, which are located close to each other, and heat is exchanged between the fuel gas (supply fuel) flowing through the fuel gas flow channel 31a and the combustion exhaust gas flowing through the combustion exhaust gas flow channel 31b. The second heat exchanger 32 is equipped with an oxidizer gas passage 32a interposed in the oxidizer electrode inlet piping 21b and a combustion exhaust gas passage 32b interposed in the combustion exhaust gas piping 21f downstream of the first heat exchanger 31 (combustion exhaust gas passage 31b), with these passages located close to each other, and exchanges heat between the air (supply air) flowing through the oxidizer gas passage 32a and the combustion exhaust gas that has passed through the first heat exchanger 31 and flows through the combustion exhaust gas passage 32b. The third heat exchanger 33 is equipped with an oxidizer gas passage 33a interposed in the oxidizer electrode inlet piping 21b downstream of the second heat exchanger 32 and a fuel off-gas passage 33b interposed in the fuel electrode outlet piping 21c, with these passages located close to each other, and exchanges heat between the supply air that has passed through the second heat exchanger 32 and flows through the oxidizer gas passage 33a and the fuel off-gas that has flowed through the fuel off-gas passage 33b.

[0023] As shown in Figure 1, the fuel supply system 40 includes a fuel supply pipe 41, one end of which is connected to a fuel supply source and the other end of which is connected to a fuel electrode inlet pipe 21a; a fuel blower 42 installed on the fuel supply pipe 41; a governor 43 installed upstream of the fuel blower 42 on the fuel supply pipe 41; and a flow meter 44 for detecting the flow rate of fuel gas flowing through the fuel supply pipe 41. In this embodiment, a hydrogen supply source such as a hydrogen tank is used as the fuel supply source. By operating the fuel blower 42, fuel gas (hydrogen gas) from the fuel supply source is supplied to the power generation module 20. The fuel gas supplied to the power generation module 20 is then heated by heat exchange with combustion exhaust gas in the first heat exchanger 31 and then supplied to the fuel electrode of the fuel cell stack 21. An ammonia supply source such as an ammonia tank may also be used as the fuel supply source. The ammonia supplied to the power generation module 20 by the operation of the fuel blower 42 is decomposed into hydrogen and nitrogen by the action of the fuel electrode catalyst, and the decomposed hydrogen is used to generate electricity in the fuel cell stack 21.

[0024] As shown in Figure 1, the air supply system 50 includes an air supply pipe 51, one end of which is connected to a filter 52 and the other end to an oxidizer electrode inlet pipe 21b, and an air blower 53 installed on the air supply pipe 51. By driving the air blower 53, the air drawn into the air supply pipe 51 via the filter 52 is introduced into the oxidizer electrode inlet pipe 21b, where it is heated to the required temperature through heat exchange with the combustion exhaust gas in the second heat exchanger 32 and heat exchange with the fuel electrode off-gas in the third heat exchanger 33 before being supplied to the oxidizer electrode of the fuel cell stack 10.

[0025] As shown in Figure 1, the recirculation system 60 includes a fuel off-gas pipe 61 connected to the other end of a hydrogen electrode outlet pipe 21c, one end of which is connected to the fuel cell stack 21; a condenser 62 installed in the fuel off-gas pipe 61; and recirculation combustion gas pipe 63 and recirculation fuel gas pipe 64, which branch off downstream of the condenser 62 in the fuel off-gas pipe 61, respectively. The condenser 62 cools the fuel off-gas by heat exchange with hot water chilling water to condense the water vapor contained in the fuel off-gas. The condensed water produced by the condensation of water vapor in the fuel off-gas in the condenser 62 is discharged through a condensed water pipe.

[0026] One end of the recirculating combustion gas pipe 63 is connected to the branching point of the fuel off-gas pipe 61, and the other end of the recirculating combustion gas pipe 63 is connected to the combustor 22 via the combustion gas pipe 21e. Similarly, one end of the recirculating fuel gas pipe 64 is connected to the branching point of the fuel off-gas pipe 61, and the other end of the recirculating fuel gas pipe 64 is connected between the fuel blower 42 and the governor 43 in the fuel supply pipe 41. As a result, the fuel off-gas that has passed through the condenser 62 is distributed to the recirculating combustion gas pipe 63 and the recirculating fuel gas pipe 64. The fuel off-gas distributed to the recirculating combustion gas pipe 63 is supplied to the combustor 22 as recirculating combustion gas. The fuel off-gas distributed to the recirculating fuel gas pipe 64 is recirculated to the fuel supply pipe 41 and supplied to the fuel electrode of the fuel cell stack 21 as recirculating fuel gas. The recirculating fuel gas pipe 64 is provided with an orifice 65 for adjusting the distribution rate of the fuel off-gas.

[0027] In the fuel cell system 10 configured in this way, as shown in Figures 3, 4, and 5, the fuel cell stack 21 and the combustor 22 are arranged in close proximity to each other in the central part of the internal space of the module case 39. The first heat exchanger 31 is arranged substantially horizontally so as to cover the fuel cell stack 21 and the combustor 22 from above in the figures, and the third heat exchanger 33 is arranged substantially vertically along the side (left side) of the fuel cell stack 21 so as to cover the fuel cell stack 21 and the combustor 22 from the side (left side) in the figures. Then, together with the first heat exchanger 31 and the third heat exchanger 33, an insulating material 34 is arranged from the side (right side) opposite to the third heat exchanger 33 to the bottom so as to surround the fuel cell stack 21 and the combustor 22 in the circumferential direction. The second heat exchanger 32 is arranged along the side (right side) of the insulating material 34 and the top surface of the first heat exchanger 31 so as to cover the side of the insulating material 34 and the top of the first heat exchanger 31. Then, together with the second heat exchanger 32, a flat plate-shaped insulating material 35 is placed on the side opposite to the second heat exchanger 32 (left side) so as to surround the first heat exchanger 31, the third heat exchanger 33, and the lateral portion of the insulating material 34 in the circumferential direction. Furthermore, as shown in Figure 5, a flat plate-shaped insulating material 36 is placed along the side (right side) of the second heat exchanger 32 so as to cover the lateral portion of the second heat exchanger 32, a flat plate-shaped insulating material 37 is placed along the top surface of the second heat exchanger 32 so as to cover the upper portion of the second heat exchanger 32, and flat plate-shaped insulating materials 38a and 38b are placed to seal the front (front) and back (back). As a result, the internal space defined by the module case 39 is formed in order from the center outwards: a high-temperature zone H1 (e.g., 600°C or higher) layer (first layer), a medium-temperature zone H2 (e.g., 400°C or higher and less than 600°C) layer (second layer), and a low-temperature zone H3 (e.g., 150°C or higher and less than 400°C) layer (third layer). Note that the arrangement of the first, second, and third heat exchangers 31, 32, 33 and the insulation materials 34, 35, 36, 37 is not limited to this, and is acceptable as long as they are arranged in layers so as to cover at least a part of the fuel cell stack 21 and the combustor 22.

[0028] In this way, the fuel cell stack 21, combustor 22, first heat exchanger 31, second heat exchanger 32, third heat exchanger 33, and insulating materials 34, 35, 36, 37, 38a, 38b form three temperature zones within the internal space of the module case 39. This allows heat from the high-temperature components located in the center of the module case 39, such as the fuel cell stack 21 and combustion section 22, to be transferred to the components located on the outside (first, second, and third heat exchangers 31, 32, 33) while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the module case 39 is sufficiently suppressed, further improving power generation efficiency. In particular, since the first heat exchanger 31 and the second heat exchanger 32 are arranged vertically above the fuel cell stack 21 and combustor 22, heat directed upward from the fuel cell stack 21 and combustor 22 can be efficiently transferred to the first heat exchanger 31 and the second heat exchanger 32. Therefore, the fuel and air supplied to the fuel cell stack 21 can be efficiently heated, further improving power generation efficiency.

[0029] Furthermore, since the fuel off-gas from the fuel electrode of the fuel cell stack 21 is supplied to a condenser 62 installed outside the power generation module 20 to condense the water vapor contained in the fuel off-gas, and then supplied to the combustor 22 as reflux combustion gas, the temperature inside the power generation module 20 can be maintained at a temperature suitable for its operation with a small amount of fuel. At this time, the fuel off-gas exchanges heat with the supplied air in the third heat exchanger 33 before being discharged outside the power generation module 20, thus further reducing the amount of heat released outside the power generation module 20. As a result, the power generation efficiency can be further improved.

[0030] It goes without saying that this disclosure is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of this disclosure.

[0031] For example, in the embodiment described above, the combustor 22 is located in the first layer between the fuel cell stack 21 and the first heat exchanger 31. However, as shown in Figure 6, it may also be located in the same layer (second layer) as the first heat exchanger 31 and the third heat exchanger 33, such as being positioned alongside the first heat exchanger 31 on either side. This allows for more efficient use of dead space, making the power generation module 20 more compact.

[0032] Furthermore, in the above-described embodiment, the power generation module 20 is equipped with first, second, and third heat exchangers 31, 32, and 33 as heat exchangers. However, the number of heat exchangers may be two or four or more, as long as multiple heat exchangers are arranged so that multiple temperature zones are formed in the internal space of the module case 39 from the center outwards. For example, the power generation module 20 may be equipped with a fourth heat exchanger located downstream of the third heat exchanger 33, comprising a fuel off-gas passage interposed in the fuel electrode outlet pipe 21c and a combustion gas passage interposed in the combustion gas pipe 21e, positioned close to each other, which exchange heat between the fuel off-gas flowing through the fuel off-gas passage and the recirculating combustion gas flowing through the combustion gas passage.

[0033] In the embodiment described above, the third heat exchanger 33 is configured to exchange heat between the supply air and the fuel off-gas, but it may also be configured to exchange heat between the supply air and the air off-gas.

[0034] Figure 7 is a schematic diagram of a power generation module 120 according to another embodiment. The power generation module 120 according to the other embodiment includes, in addition to the fuel cell stack 21 and combustor 22 similar to the power generation module 20 of this embodiment, first, second, third, and fourth heat exchangers 131, 132, 133, and 134. The first, second, third, and fourth heat exchangers 131, 132, 133, and 134 are flat plate-shaped heat exchangers with meandering flow channels formed inside. The first heat exchanger 131 includes an oxidizer gas flow channel 131a interposed in the oxidizer electrode inlet piping 21b and a combustion exhaust gas flow channel 131b interposed in the combustion exhaust gas piping 21f, positioned close to each other, and exchanges heat between the air (supply air) flowing through the oxidizer gas flow channel 131a and the combustion exhaust gas flowing through the combustion exhaust gas flow channel 131b. The second heat exchanger 132 is equipped with an oxidizer gas passage 132a located upstream of the first heat exchanger 131 (oxidizer gas passage 131a) and interposed in the oxidizer electrode inlet piping 21b, and a combustion exhaust gas passage 132b located downstream of the first heat exchanger 131 (combustion exhaust gas passage 131b) and interposed in the combustion exhaust gas piping 21f, both located close to each other. The second heat exchanger 132 exchanges heat between the supply air flowing through the oxidizer gas passage 132a and the combustion exhaust gas that has passed through the first heat exchanger 131 and flows through the combustion exhaust gas passage 132b. The supply air that has passed through the second heat exchanger 132 flows through the oxidizer gas passage 131a of the first heat exchanger 131, exchanges heat with the combustion exhaust gas flowing through the combustion exhaust gas passage 131b, and is then supplied to the oxidizer electrode of the fuel cell stack 21.

[0035] The third heat exchanger 133 is equipped with a fuel gas passage 133a interposed in the fuel electrode inlet piping 21a and a fuel off-gas passage 133b interposed in the fuel electrode outlet piping 21c, located close to each other, and exchanges heat between the fuel gas (supply fuel) flowing through the fuel gas passage 133a and the fuel off-gas flowing through the fuel off-gas passage 133b. The fourth heat exchanger 134 is equipped with a fuel gas passage 134a interposed in the fuel electrode inlet piping 21a upstream of the third heat exchanger 133 (fuel gas passage 133a) and a fuel off-gas passage 134b interposed in the fuel electrode outlet piping 21c downstream of the third heat exchanger 133 (fuel off-gas passage 133b), located close to each other, and exchanges heat between the supply fuel flowing through the fuel gas passage 134a and the fuel off-gas flowing through the fuel off-gas passage 134b after passing through the third heat exchanger 133. The supplied fuel that has passed through the fourth heat exchanger 134 flows through the fuel gas passage 133a of the third heat exchanger 133, exchanges heat with the fuel off-gas flowing through the fuel off-gas passage 133b, and is then supplied to the fuel electrode of the fuel cell stack 21.

[0036] In the power generation module 120 according to the other embodiment configured in this way, as shown in Figure 7, the first heat exchanger 131 is arranged substantially horizontally so as to cover the fuel cell stack 21 and combustor 22 from above in the figure, and the third heat exchanger 133 is arranged substantially vertically along the side (left side) of the fuel cell stack 21 so as to cover the fuel cell stack 21 and combustor 22 from the side (left side) in the figure. Then, together with the first heat exchanger 131 and the third heat exchanger 133, an insulating material 34 is arranged from the side (right side) opposite to the third heat exchanger 133 to the bottom so as to surround the fuel cell stack 21 and combustor 22 in the circumferential direction. Furthermore, the second heat exchanger 132 is arranged substantially vertically along the side (right side) of the insulating material 34 so as to cover the lateral portion of the insulating material 34, and the fourth heat exchanger 134 is arranged substantially horizontally along the top surface of the first heat exchanger 131 so as to cover the upper portion of the first heat exchanger 131. Then, together with the second heat exchanger 132 and the fourth heat exchanger 134, a flat plate-shaped insulating material 35 is placed along the side (left side) of the third heat exchanger 133, surrounding the first heat exchanger 131, the third heat exchanger 133, and the lateral portion of the insulating material 34. Furthermore, a flat plate-shaped insulating material 36 is placed along the side (right side) of the second heat exchanger 132 to cover the lateral portion of the second heat exchanger 132, a flat plate-shaped insulating material 37 is placed along the top surface of the fourth heat exchanger 134 to cover the upper portion of the fourth heat exchanger 134, and a flat plate-shaped insulating material (not shown) is placed to seal the front (front) and back (back).

[0037] In this way, the fuel cell stack 21 and combustor 22 are double-enclosed circumferentially by the first heat exchanger 131, the second heat exchanger 132, the third heat exchanger 133, the fourth heat exchanger 134, and the insulating materials 34, 35, 36, and 37. This allows heat from the high-temperature components of the fuel cell stack 21 and combustion section 22, which are located in the central part of the internal space of the module case 39, to be transferred to the components located on the outside (first, second, third, and fourth heat exchangers 131, 132, 133, and 134), while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the module case 39 can be sufficiently suppressed, and power generation efficiency can be further improved. In particular, since the first heat exchanger 131 and the fourth heat exchanger 134 are arranged stacked vertically above the fuel cell stack 21 and combustor 22, heat directed upward from the fuel cell stack 21 and combustor 22 can be efficiently transferred to the first heat exchanger 131 and the fourth heat exchanger 134. Therefore, the fuel and air supplied to the fuel cell stack 21 can be efficiently heated, further improving power generation efficiency.

[0038] Figure 8 is a schematic diagram of a power generation module 220 according to another embodiment. The power generation module 220 according to the other embodiment includes a fuel cell stack 21 and a combustor 22 similar to the power generation module 20 of this embodiment, as well as first and second heat exchangers 231 and 232. The first and second heat exchangers 231 and 232 are flat plate-shaped heat exchangers with meandering flow paths formed inside, which are bent in a roughly L-shape when viewed from the front. The first heat exchanger 231 includes a fuel gas flow path 231a interposed in the fuel electrode inlet piping 21a and a combustion exhaust gas flow path 231b interposed in the combustion exhaust gas piping 21f, positioned close to each other, and exchanges heat between the fuel gas (supply fuel) flowing through the fuel gas flow path 231a and the combustion exhaust gas flowing through the combustion exhaust gas flow path 231b. The second heat exchanger 232 is equipped with an oxidizer gas passage 232a interposed in the oxidizer electrode inlet pipe 21b and a fuel off-gas passage 232b interposed in the fuel electrode outlet pipe 21c, located close to each other, and exchanges heat between the air (supply air) flowing through the oxidizer gas passage 232a and the fuel off-gas flowing through the fuel off-gas passage 232b.

[0039] In the power generation module 220 according to the other embodiment configured in this way, as shown in Figure 8, the first heat exchanger 231 is arranged to cover the fuel cell stack 21 and the combustor 22 from the side (left side) to the top in the figure. A heat insulating material 34 is arranged from the side (right side) opposite to the first heat exchanger 231 to the bottom so as to surround the fuel cell stack 21 and the combustor 22 in the circumferential direction together with the first heat exchanger 231. The second heat exchanger 232 is arranged along the side (right side) of the heat insulating material 34 and the top surface of the first heat exchanger 231 so as to cover the side portion (right side) of the heat insulating material 34 and the upper portion of the first heat exchanger 231. A flat plate-shaped heat insulating material 35 is arranged on the side (left side) of the first heat exchanger 231 so as to surround the first heat exchanger 232 and the side (right side) of the heat insulating material 34 in the circumferential direction together with the second heat exchanger 232. Furthermore, a flat plate-shaped insulating material 36 is placed to cover the lateral portion (right side) of the second heat exchanger 232, an insulating material 37 is placed to cover the upper portion of the second heat exchanger 232, and a flat plate-shaped insulating material (not shown) is placed to block the front (front) and back (back).

[0040] In this way, the fuel cell stack 21 and combustor 22 are double-enclosed circumferentially by the first heat exchanger 231, the second heat exchanger 232, and the insulating materials 34, 35, 36, and 37. This allows heat from the high-temperature components of the fuel cell stack 21 and combustion section 22, which are located in the central part of the internal space of the module case 39, to be transferred to the components located on the outside (first and second heat exchangers 231 and 232), while suppressing heat dissipation from the high-temperature components. As a result, heat dissipation to the outside of the module case 39 is sufficiently suppressed, and power generation efficiency can be further improved. In particular, since the first heat exchanger 231 and the second heat exchanger 234 are arranged stacked vertically above the fuel cell stack 21 and combustor 22, heat directed upward from the fuel cell stack 21 and combustor 22 can be efficiently transferred to the first heat exchanger 231 and the second heat exchanger 234. Therefore, the fuel and air supplied to the fuel cell stack 21 can be efficiently heated, further improving power generation efficiency.

[0041] In the power generation modules 120 and 220 according to the other embodiments described above, the combustor 22 is located in the first layer between the fuel cell stack 21 and the first heat exchangers 131 and 231. However, it may also be located in the same layer (second layer) as the first heat exchangers 131 and 231, such as by being positioned alongside them on either side.

[0042] In the power generation module 20 of the above-described embodiment and the power generation modules 120 and 220 of the other embodiments, an insulating material 34 is placed at the bottom, and heat exchangers (first heat exchangers 31, 131, 231, second heat exchangers 32, 132, 232, third heat exchangers 33, 133, fourth heat exchanger 134) and insulating materials 35, 36, 37 are arranged to double-enclose the fuel cell stack 21 and combustor 22 from above and both sides. However, the power generation module may be configured so that at least the fuel cell stack 21 is surrounded all around by one or more heat exchangers. Alternatively, the power generation module may be arranged so that at least the fuel cell stack 21 is surrounded once by one or more heat exchangers from above and both sides.

[0043] Furthermore, this specification also discloses a technical concept in which the fuel cell system described in any one of claims 1 to 3 in claim 5 of the original application was changed to a fuel cell system described in any one of claims 1 to 4. [Industrial applicability]

[0044] This disclosure can be used in industries such as the manufacturing of fuel cell systems. [Explanation of Symbols]

[0045] 10 Fuel cell system, 21 Fuel cell stack, 21d Oxidizer electrode outlet piping (oxidizer off-gas supply line), 22 Combustor (combustion section), 31 First heat exchanger (first heat exchange section), 31a Fuel gas flow path, 31b Combustion exhaust gas flow path (first combustion exhaust gas flow path), 32 Second heat exchanger (second heat exchange section), 32a Oxidizer gas flow path (first oxidizer gas flow path), 32b Fuel exhaust gas flow path (second combustion gas flow path), 33 Third heat exchanger (third heat exchange section), 33a Oxidizer gas flow path (second oxidizer gas flow path), 33b Fuel off-gas flow path (off-gas flow path), 34, 35, 36, 37 Insulation material, 38 Module case (case), 41 Fuel supply pipe (fuel gas supply line), 61 Fuel off-gas piping (fuel off-gas supply line), 62 Condenser (condensing section), 64 65 Recirculating fuel gas piping (recirculation line), 65 Recirculating combustion gas piping (combustion fuel supply line).

Claims

1. A fuel cell that generates electricity through the reaction between a fuel gas supplied to the fuel electrode and an oxidizer gas supplied to the oxidizer electrode, A combustion section for burning flammable gas, The fuel cell has a low-temperature gas passage through which a low-temperature gas, which is a fuel gas or oxidizer gas supplied to the fuel cell, flows, and a high-temperature gas passage through which a high-temperature gas, which is an off-gas discharged from the fuel cell or a combustion exhaust gas discharged from the combustion section, and a plurality of heat exchange units that exchange heat between the low-temperature gas flowing through the low-temperature gas passage and the high-temperature gas flowing through the high-temperature gas passage, A case having thermal insulation properties, which houses the fuel cell, the combustion section, and the plurality of heat exchange sections, A fuel cell system comprising, At least the fuel cell, the combustion section, and the plurality of heat exchange sections are arranged in layers such that a first, second, and third temperature zone are formed sequentially from the center outward within the internal space of the case. The fuel cell is arranged in the first layer, The combustion section is arranged in the first layer or the second layer. One or more of the aforementioned plurality of heat exchange sections are arranged in the second layer. One or more of the aforementioned heat exchange sections are arranged in the third layer. Fuel cell system.

2. A fuel cell system according to claim 1, The aforementioned plurality of heat exchange units are The first heat exchange unit has a fuel gas passage through which the fuel gas flows as the low-temperature gas and a first combustion exhaust gas passage through which the combustion exhaust gas flows as the high-temperature gas, and exchanges heat between the fuel gas flowing through the fuel gas passage and the combustion exhaust gas flowing through the first combustion exhaust gas passage. The second heat exchange section has a first oxidant gas passage through which the oxidant gas flows as the low-temperature gas, and a second combustion exhaust gas passage through which the combustion exhaust gas that has passed through the first heat exchange section flows as the high-temperature gas, and the second heat exchange section exchanges heat between the oxidant gas flowing through the first oxidant gas passage and the combustion exhaust gas flowing through the second combustion exhaust gas passage, A third heat exchange unit has a second oxidant gas flow path through which the oxidant gas that has passed through the second heat exchange unit flows as the low-temperature gas, and an off-gas flow path through which the fuel off-gas or the oxidant off-gas flows as the high-temperature gas, and exchanges heat between the oxidant gas flowing through the second oxidant gas flow path and the fuel off-gas or the oxidant off-gas flowing through the off-gas flow path, Includes, The one or more heat exchange sections are the first heat exchange section and the third heat exchange section, The one or more other heat exchange sections are the second heat exchange section. Fuel cell system.

3. A fuel cell system according to claim 2, A fuel gas supply line that supplies the fuel gas to the fuel electrode, A condensing unit is located outside the case and condenses the water vapor contained in the fuel off-gas, A fuel off-gas supply line that supplies the fuel off-gas to the condensing section, A return line that returns a portion of the fuel off-gas that has passed through the condensation section to the fuel gas supply line, A combustion fuel supply line supplies the remaining portion of the fuel off-gas that has passed through the condensation section to the combustion section, An oxidizer off-gas supply line supplies the oxidizer off-gas discharged from the oxidizer electrode to the combustion section, Equipped with, The third heat exchange section has a fuel off-gas passage through which the fuel off-gas flows as the high-temperature gas, and it exchanges heat between the oxidizer gas flowing through the second oxidizer gas passage and the fuel off-gas flowing through the fuel off-gas passage. The fuel off-gas supply line supplies the fuel off-gas that has passed through the third heat exchange section to the condenser section. Fuel cell system.

4. A fuel cell system according to any one of claims 1 to 3, The one or more heat exchange units are arranged in combination with an insulating material to cover at least a portion of the fuel cell and the combustion unit. Fuel cell system.

5. A fuel cell system according to any one of claims 1 to 3, The one or more other heat exchange units are arranged to cover the one or more heat exchange units in combination with an insulating material. Fuel cell system.

Images