Fuel cell system

Abstract

To provide a fuel cell system having a simple configuration.SOLUTION: A fuel cell system 100 comprises a hot module 1 including a combustion part 15 for combusting off-gas discharged from a cell stack 14 for generating power using fuel gas and oxidant gas, a gas circulation line L7 through which gas discharged from the hot module 1 circulates, a water recovery part 71 for recovering water contained in gas circulating through the gas circulation line L7, a temperature adjustment part 8 that is on a downstream side of the hot module 1 and on an upstream side of the water recovery part 71 in a gas circulation direction and adjusts a temperature of gas circulating in the gas circulation line L7, and a housing 100H. The temperature adjustment part 8 comprises a first flow line L81 and a second flow line L82 having radiation performance higher than that of the first flow line L81. When a temperature inside the housing 100H is influenced by an outside air temperature and becomes equal to or higher than a predetermined temperature threshold, a flow rate adjustment part 82 reduces a flow rate of gas circulating in the first flow line L81 and increases a flow rate of gas circulating in the second flow line L82.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fuel cell system. [Background technology]

[0002] Patent Document 1 discloses a solid oxide fuel cell system that suppresses a decrease in hydrodesulfurization performance. The solid oxide fuel cell system disclosed in Patent Document 1 includes a solid oxide fuel cell, a hydrodesulfurizer that removes sulfur components from fuel gas, a reformer that produces reformed gas by reforming the fuel gas desulfurized in the hydrodesulfurizer, an anode offgas radiator that radiates heat from anode offgas from the solid oxide fuel cell, and a cooler (absorption chiller) that cools at least a portion of the anode offgas, and suppresses a decrease in hydrodesulfurization performance by cooling the anode offgas to reduce the amount of moisture contained in the anode offgas before supplying it to the hydrodesulfurizer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-146225 Summary of the Invention [Problem to be solved by the invention]

[0004] A system that uses an absorption refrigerator to cool gas, such as the solid oxide fuel cell system disclosed in Patent Document 1, has a large-scale configuration.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its purpose is to provide a fuel cell system that can reduce the amount of water contained in the gas discharged from the hot module with a simple configuration. [Means for solving the problem]

[0006] The fuel cell system according to the present invention, which achieves the above object, has the following characteristic configuration: a hot module having a container, a cell stack in which a plurality of fuel cell units each having an anode and a cathode are provided and which generates electricity using a fuel gas and an oxidant gas, and a combustion unit which combusts anode off-gas and cathode off-gas discharged from the cell stack; a raw fuel supply unit that supplies raw fuel from outside the container to the hot module; an oxidant gas supply unit that supplies the oxidant gas from outside the container to the cell stack; a gas flow passage through which gas discharged from the hot module flows; a moisture recovery unit that recovers moisture contained in the gas flowing through the gas flow passage, a temperature adjusting unit that adjusts the temperature of the gas flowing through the gas flow passage, the temperature adjusting unit being located downstream of the hot module and upstream of the moisture recovery unit in the gas flow direction; a housing that houses the hot module, the raw fuel supply unit, the oxidant gas supply unit, the gas flow channel, the moisture recovery unit, and the temperature adjustment unit, the temperature adjustment unit includes a first flow path, a second flow path having a higher heat dissipation performance than the first flow path, and a flow rate adjustment unit capable of adjusting a flow rate of the gas flowing through the first flow path and a flow rate of the gas flowing through the second flow path, The flow rate adjustment unit reduces the flow rate of the gas flowing through the first flow path and increases the flow rate of the gas flowing through the second flow path when the temperature inside the housing, which is affected by the outside air temperature, reaches or exceeds a predetermined temperature threshold.

[0007] According to the above-described characteristic configuration, by simply passing the gas through the second flow path, which has a higher heat dissipation performance than the first flow path, the temperature of the gas discharged from the hot module can be lowered, the amount of moisture recovered by the moisture recovery unit can be increased, and the amount of moisture contained in the gas can be reduced. Therefore, the amount of moisture contained in the gas discharged from the hot module can be reduced with a simple configuration.

[0008] Another characteristic feature of the fuel cell system according to the present invention is that the length of the second flow path is longer than the length of the first flow path.

[0009] According to the above characteristic configuration, simply by making the length of the second flow path longer than the length of the first flow path, the temperature of the gas discharged from the hot module can be lowered, the amount of moisture recovered by the moisture recovery unit can be increased, and the amount of moisture contained in the gas can be reduced. Therefore, the amount of moisture contained in the gas discharged from the hot module can be reduced with a simple configuration.

[0010] Another characteristic configuration of the fuel cell system according to the present invention is: The temperature adjusting unit further includes a heat exchanger disposed in the second flow path and exchanging heat between the gas flowing through the second flow path and the refrigerant.

[0011] According to the above characteristic configuration, the gas temperature can be more effectively lowered, the amount of moisture recovered in the moisture recovery section can be increased, and the amount of moisture contained in the gas can be reduced. Therefore, the amount of moisture contained in the gas discharged from the hot module can be reduced with a simple configuration.

[0012] Another characteristic configuration of the fuel cell system according to the present invention is: the hot module further includes a reforming unit that steam reforms the raw fuel to generate the fuel gas, and a fuel gas supply path that supplies the fuel gas from the reforming unit to the anode, the gas flow passage is a reflux gas flow passage that refluxes the reflux gas, which is the gas discharged from the reforming unit of the hot module, to the raw fuel supply unit, The reflux gas, whose temperature is adjusted in the temperature adjustment section, flows through the reflux gas flow path, and from which moisture is recovered in the moisture recovery section, is supplied to a desulfurizer that desulfurizes the raw fuel to be supplied to the reforming section.

[0013] According to the above characteristic configuration, the temperature of the recirculated gas can be lowered, the amount of moisture recovered in the moisture recovery section can be increased, and the amount of moisture contained in the recirculated gas can be reduced. Therefore, the amount of moisture contained in the recirculated gas discharged from the hot module can be reduced with a simple configuration. Furthermore, since the recirculated gas with reduced moisture content is supplied to the desulfurizer, the deterioration of the desulfurization performance in the desulfurizer can also be reduced.

[0014] Another characteristic configuration of the fuel cell system according to the present invention is: the gas flow passage is a combustion exhaust gas passage through which combustion exhaust gas generated in the combustion section is discharged from the container, The combustion exhaust gas, whose temperature has been adjusted by the temperature adjustment unit and which has flowed through the combustion exhaust gas passage, is supplied to the moisture recovery unit.

[0015] According to the above-mentioned characteristic configuration, the temperature of the combustion exhaust gas can be lowered and the moisture contained in the combustion exhaust gas can be recovered as reforming water, which eliminates the need to introduce reforming water from an external source and enables the fuel cell system to become water self-sufficient.

[0016] Another characteristic configuration of the fuel cell system according to the present invention is: The housing has an outer wall surface to which a temperature rise prevention material for preventing a temperature rise is applied or attached.

[0017] According to the above-described characteristic configuration, it is possible to suppress the temperature rise inside the housing due to the irradiation of sunlight, and it is also possible to suppress the temperature rise of the gas discharged from the hot module, particularly in the summer. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram showing the configuration of a fuel cell system according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the appearance of an outer container according to the first embodiment. [Figure 3]FIG. 10 is a schematic diagram showing the configuration of a fuel cell system according to a second embodiment. [Figure 4] FIG. 10 is a schematic diagram showing the configuration of a fuel cell system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] A fuel cell system 100 according to an embodiment of the present invention will be described below with reference to the drawings. FIG.

[0020] First Embodiment [Fuel cell system] 1, the fuel cell system 100 includes a hot module 1, a reforming water supply unit 2, a raw fuel supply unit 3, an oxidant gas supply unit 4, a heat exchange unit 5, a hot water / water circulation unit 6, a gas reflux unit 7, a control unit 9, and an external container 100H (an example of a housing). The external container 100H houses the hot module 1, the reforming water supply unit 2, the raw fuel supply unit 3, the oxidant gas supply unit 4, the heat exchange unit 5, the hot water / water circulation unit 6, the gas reflux unit 7, and the control unit 9. The inside of the external container 100H is easily affected by the outside temperature.

[0021] 2, in this embodiment, the outer container 100H is a rectangular parallelepiped and includes an outer wall surface (hereinafter referred to as an irradiated surface GS) onto which sunlight can be irradiated. The irradiated surface GS is, for example, a wall surface other than a bottom surface GD facing the ground GL on which the outer container 100H is placed and a back surface GH facing a wall HG of a building such as a house.

[0022] The outer container 100H further includes a temperature rise prevention material PS that prevents a temperature rise inside the outer container 100H. The temperature rise prevention material PS is applied to or attached to the irradiation surface GS. The temperature rise prevention material PS is, for example, a sheet that can change color with temperature rise (turning white or transparent (with a silver or other base if transparent) when the temperature is higher than a predetermined temperature, and turning black when the temperature is lower than the predetermined temperature), a reflective sheet that can reflect solar radiation, a radiative cooling sheet that can reflect solar radiation and emit infrared rays, etc.

[0023] [Hot Module] As shown in Fig. 1, hot module 1 is supplied with reforming water, raw fuel, and oxidant gas (air) from a reforming water supply unit 2, a raw fuel supply unit 3, and an oxidant gas supply unit 4, respectively. Hot module 1 is a fuel cell module that generates electricity by reacting hydrogen contained in the raw fuel with oxygen contained in the oxidant gas. Hot module 1 has an inner container 1H (an example of a container), a desulfurization unit 11 (an example of a desulfurizer), a vaporization unit 12, a reforming unit 13, a cell stack 14, a combustion unit 15, and a combustion catalyst unit 16.

[0024] The inner vessel 1H has heat insulating properties and houses the desulfurization section 11, the vaporization section 12, the reforming section 13, the cell stack 14, the combustion section 15, and the combustion catalyst section 16. An exhaust port 111 is formed in the inner vessel 1H.

[0025] [Desulfurization section] The desulfurization unit 11 removes sulfur from the raw fuel supplied to the hot module 1. The desulfurization unit 11 performs desulfurization by, for example, hydrodesulfurization.

[0026] [Vaporization section] The vaporization unit 12 is supplied with reforming water, raw fuel, and combustion heat generated in the combustion unit 15. The vaporization unit 12 uses the combustion heat to vaporize the reforming water and generate steam. In this embodiment, the vaporization unit 12 supplies a mixed gas obtained by mixing the raw fuel with steam vaporized from the reforming water to the reforming unit 13.

[0027] [Modification section] The reforming section 13 is supplied with the mixed gas from the vaporizing section 12. Note that the raw fuel may be supplied directly to the reforming section 13 from the raw fuel supply section 3 without passing through the vaporizing section 12.

[0028] In addition to the mixed gas, combustion heat generated in the combustion section 15 is supplied to the reforming section 13. The reforming section 13 generates fuel gas by steam reforming the mixed gas (raw fuel) by utilizing the combustion heat. The fuel gas generated in the reforming section 13 is supplied to the cell stack 14. The fuel gas is supplied to the cell stack 14, for example, via a fuel gas supply path.

[0029] [Cell stack] The cell stack 14 is made up of multiple cells C (an example of a fuel cell). In this embodiment, the cells C are solid oxide fuel cells, each having an anode (combustion electrode), a cathode (air electrode), and an electrolyte. For this reason, the fuel cell system in this embodiment is also called a solid oxide fuel cell system.

[0030] Fuel gas and oxidant gas are supplied to cell C, and electricity is generated based on the fuel gas and oxidant gas. Specifically, cell C generates electricity by chemically reacting hydrogen contained in the fuel gas with oxygen contained in the oxidant gas. The fuel gas (anode off-gas) and oxidant gas (cathode off-gas) that are not used for power generation are discharged as off-gas (excess gas).

[0031] [Combustion section] The combustion unit 15 is supplied with off-gas discharged from the cell stack 14 and generates combustion heat by combusting the off-gas. The combustion unit 15 is disposed between the vaporization unit 12 and the reforming unit 13 and the cell stack 14, and the combustion heat generated in the combustion unit 15 increases the temperature of the internal space of the inner container 1H. The combustion unit 15 discharges combustion exhaust gas along with the fuel of the off-gas. The combustion exhaust gas is supplied to the combustion catalyst unit 16 disposed at the exhaust port 111.

[0032] [Combustion catalyst section] The combustion catalyst section 16 uses oxygen to catalytically combust hydrogen, carbon monoxide, and the like contained in the combustion exhaust gas. The catalytically combusted combustion exhaust gas is discharged to the outside of the inner container 1H.

[0033] [Reformed Water Supply Department] The reforming water supply unit 2 supplies reforming water from outside the inner vessel 1H to the hot module 1. The reforming water is, for example, tap water from which impurities have been removed. The reforming water supply unit 2 includes a reforming water supply passage L1, an ion exchange resin 20, a water tank 21, and a pump 22.

[0034] The ion exchange resin 20 removes impurities from the reforming water (purifying the reforming water) and supplies it to the water tank 21. The water tank 21 stores the reforming water. The pump 22 pumps the reforming water stored in the water tank 21. As a result, the reforming water is supplied to the hot module 1 via the reforming water supply path L1. In this embodiment, the pump 22 circulates the reforming water used in the hot module 1 between the hot module 1 and the water tank 21. The amount of reforming water supplied to the hot module 1 per unit time is adjusted by controlling the operation of the pump 22.

[0035] [Raw and fuel supply department] The raw fuel supply unit 3 supplies raw fuel from the outside of the inner vessel 1H to the hot module 1. The raw fuel contains hydrocarbons, such as city gas and LP gas.

[0036] The raw fuel supply unit 3 has a raw fuel supply path L2, a solenoid valve 31, a fuel flow meter 32, a raw fuel orifice 33, and a gas blower 34. The solenoid valve 31 can adjust the flow rate of the raw fuel flowing through the raw fuel supply path L2. The fuel flow meter 32 measures the flow rate of the raw fuel flowing through the raw fuel supply path L2. The raw fuel orifice 33 adjusts the flow rate of the raw fuel by changing the cross-sectional area of ​​the raw fuel flow path. The gas blower 34 supplies the raw fuel to the hot module 1 via the raw fuel supply path L2. The amount of raw fuel supplied to the hot module 1 per unit time is adjusted by controlling the operation of the solenoid valve 31 and / or the gas blower 34.

[0037] [Oxidant gas supply unit] The oxidizing gas supply unit 4 supplies an oxidizing gas from the outside of the inner vessel 1H to the hot module 1. The oxidizing gas contains oxygen and is, for example, air.

[0038] The oxidant gas supply unit 4 has an oxidant gas supply channel L3, an oxidant gas blower 41, and an oxidant gas flow meter 42. The oxidant gas blower 41 supplies oxidant gas to the hot module 1 via the oxidant gas supply channel L3. The oxidant gas flow meter 42 measures the flow rate of the oxidant gas flowing through the oxidant gas supply channel L3. The amount of oxidant gas supplied to the hot module 1 per unit time is adjusted by controlling the operation of the oxidant gas blower 41.

[0039] [Heat exchange section] The heat exchange section 5 condenses and recovers moisture contained in the combustion exhaust gas supplied from the combustion catalyst section 16. The heat exchange section 5 has a combustion exhaust gas passage L4, a heat exchanger 51 (an example of a water recovery section), and a water recovery passage L5.

[0040] The combustion exhaust gas passage L4 is connected to the combustion catalyst section 16 and the heat exchanger 51. The combustion exhaust gas is supplied from the combustion catalyst section 16 to the heat exchanger 51 via the combustion exhaust gas passage L4.

[0041] In the heat exchanger 51, heat is exchanged between the combustion exhaust gas and the hot water circulating through the hot water circulation section 6. This cools the combustion exhaust gas and heats the hot water. When the combustion exhaust gas is cooled, the water contained in the combustion exhaust gas condenses and becomes a liquid (liquid phase). The gas phase components in the combustion exhaust gas are discharged to the outside of the outer container 100H via the combustion exhaust gas passage L4, and the liquid phase components (condensed water) in the combustion exhaust gas are supplied to the water recovery passage L5.

[0042] The water recovery line L5 branches off from the combustion exhaust gas line L4 downstream of the heat exchanger 51 in the flow direction of the combustion exhaust gas, and is connected to the reforming water supply unit 2. The condensed water guided to the water recovery line L5 is supplied to the water tank 21 of the reforming water supply unit 2 via the ion exchange resin 20, and is stored in the water tank 21 as reforming water. In other words, the reforming water is supplied from the water tank 21 to the hot module 1, used for power generation, and then returned to the water tank 21.

[0043] [Hot water circulation section] The hot and cold water circulation unit 6 has a hot and cold water circulation path L6, a hot and cold water tank 61, a hot and cold water circulation pump 62, and a hot and cold water cooling unit 63.

[0044] The hot water tank 61 stores hot water. The bottom and top of the hot water tank 61 are connected to the hot water circulation path L6. The hot water circulation pump 62 circulates hot water between the hot water tank 61 and the heat exchanger 5 via the hot water circulation path L6. More specifically, the hot water circulation pump 62 pressure-feeds hot water from the bottom of the hot water tank 61 through the heat exchanger 51 to the top of the hot water tank 61. In other words, hot water flows out from the bottom of the hot water tank 61 into the hot water circulation path L6, and hot water heated in the heat exchanger 5 returns from the top to the hot water tank 61. The hot water cooling unit 63 is, for example, a radiator, and cools the hot water upstream of the heat exchanger 5 in the direction of hot water flow.

[0045] [Gas return section] The gas reflux unit 7 refluxes the mixed gas from the reforming unit 13 (an example of the gas discharged from the hot module 1), the mixed gas having its temperature adjusted (lowered) by a temperature adjustment unit 8 described below, to the raw fuel supply unit 3. The gas reflux unit 7 has a reflux gas flow path L7 (an example of a gas flow passage), a gas-liquid separator 71 (an example of a moisture recovery unit), a reflux gas orifice 72, and the temperature adjustment unit 8.

[0046] The recirculation gas flow path L7 is connected to the hot module 1 and the raw fuel supply unit 3. The recirculation gas flow path L7 recirculates the mixed gas from the reforming unit 13 through the temperature adjustment unit 8 to the raw fuel supply unit 3 (raw fuel supply path L2). Specifically, the recirculation gas flow path L7 recirculates the mixed gas upstream of the raw fuel orifice 33 of the raw fuel supply path L2 in the flow direction of the raw fuel. The recirculation gas flow path L7 includes a first recirculation gas flow path L71 and a second recirculation gas flow path L72, and the first recirculation gas flow path L71 and the second recirculation gas flow path L72 are each connected to the raw fuel supply path L2. In this embodiment, the second recirculation gas flow path L72 is connected upstream of the first recirculation gas flow path L71 in the flow direction of the raw fuel. However, the second recirculation gas flow path L72 may be connected downstream of the first recirculation gas flow path L71 in the flow direction of the raw fuel.

[0047] The gas-liquid separator 71 recovers (separates) water (moisture) contained in the recirculation gas flowing through the recirculation gas flow path L7. The water separated by the gas-liquid separator 71 is supplied to the reforming water supply unit 2, passes through the ion exchange resin 20, and is stored in the water tank 21. The gas-liquid separator 71 is, for example, a drain trap. In this embodiment, the gas-liquid separator 71 includes a first gas-liquid separator 711 and a second gas-liquid separator 712, and the first gas-liquid separator 711 is disposed in the first recirculation gas flow path L71, and the second gas-liquid separator 712 is disposed in the second recirculation gas flow path L72.

[0048] The recirculation gas orifice 72 adjusts the flow rate of the recirculation gas by changing the cross-sectional area of ​​the recirculation gas flow path. The recirculation gas orifice 72 includes a first orifice 721 and a second orifice 722. The first orifice 721 is disposed downstream of the first gas-liquid separator 711 in the flow direction of the recirculation gas flowing through the first recirculation gas flow path L71, and the second orifice 722 is disposed downstream of the second gas-liquid separator 712 in the flow direction of the recirculation gas flowing through the second recirculation gas flow path L72.

[0049] [Temperature adjustment section] The temperature adjustment unit 8 adjusts the temperature of the reflux gas, which is a mixed gas (an example of a gas) discharged from the hot module 1 (reforming unit 13). The temperature adjustment unit 8 is disposed downstream of the hot module 1 (upstream of the gas reflux unit 7) in the flow direction of the reflux gas. The temperature adjustment unit 8 includes a temperature adjustment flow path L8, a temperature acquisition unit 81, an adjustment valve 82 (an example of a flow rate adjustment unit), and a reflux gas heat exchanger 83 (an example of a heat exchanger). In this embodiment, the temperature adjustment flow path L8 is configured as a portion of the upstream side of the reflux gas flow path L7.

[0050] The temperature adjustment passage L8 is connected to the hot module 1 (reforming section 13), and the mixed gas from the hot module 1 (reforming section 13) flows into the temperature adjustment passage L8 as reflux gas. The reflux gas passes through the temperature adjustment passage L8 and is supplied to the raw fuel supply passage L2. In this embodiment, the temperature adjustment passage L8 includes a common passage L80, a first passage L81, and a second passage L82. Note that in this embodiment, a portion of the first reflux gas passage L71 functions as the first passage L81, and a portion of the second reflux gas passage L72 functions as the second passage L82.

[0051] The common flow path L80 has an upstream end in the flow direction of the reflux gas connected to the hot module 1, and the reflux gas discharged from the reforming section 13 flows through the common flow path L80. The first flow path L81 and the second flow path L82 each extend from a first branch point P1, which is the downstream end of the common flow path L80.

[0052] The second flow path L82 is configured to have higher heat dissipation performance than the first flow path L81. In this embodiment, the second flow path L82 is configured to be longer than the first flow path L81. Therefore, the reflux gas is more easily cooled while flowing through the second flow path L82 than while flowing through the first flow path L81.

[0053] The temperature acquisition unit 81 acquires the temperature of the mixed gas (recirculated gas) discharged from the reforming unit 13. The temperature acquisition unit 81 is disposed in the common flow path L80 and acquires the temperature of the recirculated gas flowing through the common flow path L80. In this embodiment, the temperature acquisition unit 81 is a temperature sensor and transmits information indicating the temperature of the recirculated gas to the control unit 9.

[0054] The adjustment valve 82 is capable of adjusting the flow rate of the reflux gas flowing through the temperature adjustment passage L8. The adjustment valve 82 is, for example, a solenoid valve. The operation of the solenoid valve is controlled, for example, by the control unit 9. In this embodiment, the adjustment valve 82 includes a first adjustment valve 821 and a second adjustment valve 822.

[0055] The first adjusting valve 821 is capable of adjusting the flow rate of the reflux gas flowing through the first flow path L81, and the second adjusting valve 822 is capable of adjusting the flow rate of the reflux gas flowing through the second flow path L82.

[0056] When the temperature acquired by the temperature acquisition unit 81 becomes equal to or higher than a preset temperature threshold, the adjustment valve 82 reduces the flow rate of the recirculation gas flowing through the first flow path L81 and increases the flow rate of the recirculation gas flowing through the second flow path L82. Specifically, the first adjustment valve 821 reduces the opening of the valve or closes the valve, and the second adjustment valve 822 opens the valve. As a result, the recirculation gas flowing through the common flow path L80 is directed to the second flow path L82, and the flow rate of the recirculation gas flowing through the first flow path L81 is reduced or the recirculation gas is stopped.

[0057] The recirculation gas heat exchanger 83 is disposed in the second flow path L82. In the recirculation gas heat exchanger 83, heat is exchanged between the recirculation gas and a refrigerant such as air (outside air). The recirculation gas is further cooled by passing through the recirculation gas heat exchanger 83.

[0058] That is, in this embodiment, the reflux gas is temperature-adjusted by the temperature adjustment unit 8, flows through the reflux gas flow path L7, and has moisture separated (recovered) by the gas-liquid separator 71, and is then supplied again to the desulfurization unit 11. In this embodiment, reflux gas having a dew point of, for example, 30 degrees or less, more preferably 20 degrees or less, is supplied to the desulfurization unit 11.

[0059] [Control Unit] The control unit 9 is composed of a microcontroller including a processor, semiconductor memory, etc. The control unit 9 controls the operation of each of the hot module 1, reforming water supply unit 2, raw fuel supply unit 3, oxidant gas supply unit 4, heat exchange unit 5, hot water circulation unit 6, and gas reflux unit 7 (temperature adjustment unit 8). The control unit 9 has a memory unit 91 composed of semiconductor memory. The memory unit 91 stores program data for the operation of the control unit 9, data indicating temperature threshold values, etc.

[0060] As described above, according to this embodiment, when the temperature inside the outer container 100H, which is affected by the outside air temperature, exceeds a temperature threshold, the flow rate of gas flowing through the first flow path L81 decreases, and the flow rate of gas flowing through the second flow path L82, which has higher cooling performance, increases. Alternatively, the gas flow path is switched from the first flow path L81 to the second flow path L82. In this embodiment, the length of the second flow path L82 is longer than the length of the first flow path L81. Therefore, the recirculated gas flows through the second flow path L82 for a longer period of time in contact with the outside air and / or the wall surfaces of the flow path. This makes the gas more likely to be cooled than through the first flow path L81. In addition, the second flow path L82 is provided with a gas heat exchanger 83, which further cools the recirculated gas. In other words, according to this embodiment, the temperature of the recirculated gas (mixed gas) discharged from the hot module 1 can be adjusted (reduced), thereby reducing the amount of moisture contained in the recirculated gas. In other words, the amount of moisture contained in the recirculated gas discharged from the hot module 1 can be reduced with a simple configuration.

[0061] Second Embodiment Next, a fuel cell system 100 according to a second embodiment will be described with reference to FIG. 3. FIG. 3 is a schematic diagram showing the fuel cell system 100 according to the second embodiment. The second embodiment differs from the first embodiment in that the gas whose temperature is adjusted by the temperature adjustment unit 8 is not the reflux gas (as in the first embodiment) that is refluxed from the reforming unit 13 to the raw fuel supply unit 3, but the combustion exhaust gas generated when the combustion unit 15 combusts offgases (anode offgas and cathode offgas) to generate combustion heat. Note that in the second embodiment, the gas reflux unit 7 does not include the second reflux gas flow path L72, but only includes the first reflux gas flow path L71. Similarly, for the gas-liquid separator 71 and the reflux gas orifice 72, the gas reflux unit 7 does not include the second gas-liquid separator 712 and the second orifice 722, but only includes the first gas-liquid separator 711 and the first orifice 721. Hereinafter, detailed descriptions of the same configurations as those in the first embodiment will be omitted.

[0062] 3, in the second embodiment, the temperature adjustment unit 8 is provided in the heat exchange unit 5, not in the gas reflux unit 7. In the second embodiment, a part of the combustion exhaust gas passage L4 (an example of a gas flow passage) upstream of the heat exchanger 51 functions as a first flow path L81 of the temperature adjustment unit 8.

[0063] In the second embodiment, similarly to the first embodiment, when the temperature inside the outer container 100H, which is affected by the outside air temperature, is below a temperature threshold, the combustion exhaust gas is controlled to flow preferentially through the first flow path L81. On the other hand, when the temperature is equal to or greater than the temperature threshold, the flow rate of gas flowing through the first flow path L81 is reduced, and the flow rate of gas flowing through the second flow path L82, which has higher cooling performance, is increased. Alternatively, the gas flow path is switched from the first flow path L81 to the second flow path L82 (the opening of the first adjustment valve 821 is reduced or closed, and the second adjustment valve 822 is opened). In the second embodiment, similarly to the first embodiment, the length of the second flow path L82 is longer than the length of the first flow path L81. Therefore, the combustion exhaust gas has a longer contact time with the outside air and / or the wall surfaces that form the flow path while flowing through the second flow path L82, and is therefore more easily cooled than while flowing through the first flow path L81. In addition, a gas heat exchanger 83 is disposed in the second flow path L82, and the combustion exhaust gas is further cooled in the gas heat exchanger 83. This makes it possible to lower the temperature of the combustion exhaust gas flowing into the heat exchanger 51. Furthermore, since flowing through the first flow path L81 reduces the pressure loss of the combustion exhaust gas more than flowing through the second flow path L82, by causing the combustion exhaust gas to flow through the second flow path L82 only when the temperature is equal to or higher than the temperature threshold, it is possible to save the power required to operate auxiliary equipment such as the pump 22, gas blower 34, and oxidizer gas blower 41. Furthermore, the load on the auxiliary equipment can be reduced, thereby extending the life of the auxiliary equipment.

[0064] <Another embodiment> The configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention.

[0065] (1) In the first embodiment, the temperature adjustment flow path L8 may further include a junction flow path L83 where the first flow path L81 and the second flow path L82 join together, as shown in Fig. 4. At least one of the reflux gas flowing through the first flow path L81 and the reflux gas flowing through the second flow path L82 flows through the junction flow path L83.

[0066] (2) When configured as described in (1) above, the gas recirculation unit 7 can omit the second gas-liquid separator 712 and the second orifice 722. In this case, the cross-sectional area of ​​the first orifice 721 is set so that the hydrogen concentration of the recirculation gas flowing through the second flow path L82 is kept at the minimum necessary value. Because the hydrogen concentration of the recirculation gas flowing through the first flow path L81 is relatively high, when the temperature of the recirculation gas is below the temperature threshold, the catalytic performance of the desulfurization unit 11 can be maintained at a high level by circulating the recirculation gas through the first flow path L81. This also contributes to maintaining high robustness of the device. However, when the ambient temperature is high and the temperature of the recirculation gas exceeds the temperature threshold, it is more important to adjust the temperature (dew point) of the recirculation gas than the hydrogen concentration. Therefore, it is desirable to maintain the temperature (dew point) of the recirculation gas at an appropriate level with the minimum necessary hydrogen concentration to maintain the catalytic resistance of the desulfurization unit 11.

[0067] (3) The configuration described in (1) above can also be applied to the case where the temperature of the temperature adjustment passage L8 is to be adjusted for combustion exhaust gas, as in the second embodiment described with reference to Fig. 3. When applied to the second embodiment, the junction passage L83 is connected to the combustion exhaust gas passage L4 upstream of the heat exchanger 51 in the flow direction of the combustion exhaust gas in the combustion exhaust gas passage L4.

[0068] (4) Although the temperature acquisition unit 81 is a temperature sensor arranged downstream of the reforming unit 13, the temperature acquisition unit 81 may acquire the temperature of the external container 100H (inside the housing) based on the value indicated by a temperature sensor arranged in the external container 100H (the temperature of the temperature measurement unit within the system, which is highly correlated with the outside air temperature), for example.

[0069] (5) In the present embodiment, the regulating valve 82 includes the first regulating valve 821 and the second regulating valve 822. However, the regulating valve 82 may include only the first regulating valve 821. Because the first flow path L81 and the second flow path L82 are different in length (because flow through the second flow path L82 results in greater pressure loss), when the first regulating valve 821 is open, the reflux gas (most of the reflux gas) flowing through the common flow path L80 flows preferentially through the first flow path L81. Note that, by allowing the reflux gas to flow preferentially through the first flow path L81, the amount of liquid separated by the gas-liquid separator 71 can be minimized. This minimizes the amount of water passing through the ion exchange resin 20, thereby preventing excessive loading of the ion exchange resin 20.

[0070] (6) The first adjustment valve 821 may be a thermostatic expansion valve other than a solenoid valve. The thermostatic expansion valve closes when the temperature around the thermostatic expansion valve (outside air temperature) is equal to or higher than a temperature threshold, and opens when the temperature around the thermostatic expansion valve is lower than the temperature threshold.

[0071] (7) In the above embodiment, the second flow path L82 is longer than the first flow path L81. However, the second flow path L82 may have a higher heat dissipation performance than the first flow path L81. For example, the reflux gas heat exchanger 83 may be disposed in the second flow path L82, and the length of the second flow path L82 may be equal to or shorter than the length of the first flow path L81. Furthermore, if the length of the second flow path L82 is longer than the length of the first flow path L81, the reflux gas heat exchanger 83 may be omitted.

[0072] (8) The configuration of the hot module 1 described in the above embodiment is an example, and the configuration within the hot module 1 can be changed as appropriate. For example, the raw fuel may be supplied directly to the reforming unit 13 from the raw fuel supply unit 3 without going through the vaporization unit 12. Furthermore, the desulfurization unit 11 may be arranged outside the hot module 1, and the raw fuel may be supplied to the vaporization unit 12 after being desulfurized by the desulfurization unit 11 arranged outside the hot module 1.

[0073] (9) The temperature rise prevention material PS may be omitted from the outer container 100H.

[0074] (10) The present invention is also applicable to fuel cells other than solid oxide fuel cells. [Industrial Applicability]

[0075] The present invention can be used in a fuel cell system. [Explanation of symbols]

[0076] 1: Hot module 1H:Inner container (container) 2: Reformed water supply section 3: Raw fuel supply section 4: Oxidant gas supply section 8: Temperature adjustment section 11: Desulfurization section (desulfurizer) 14: Cell stack 15: Combustion section 51: Heat exchanger (water recovery section) 71: Gas-liquid separator (water recovery section) 82: Regulating valve (flow rate adjusting part) 83: Reflux gas heat exchanger (heat exchanger) 100: Fuel cell system 100H: Outer container (housing) C: Cell (fuel cell) GS: Irradiation surface (exterior wall surface) L4: Combustion exhaust gas passage (gas flow passage) L7: Circulation gas flow path (gas flow path) L81: First flow path L82: Second flow path PS: Temperature rise prevention material

Claims

1. a hot module having a container, a cell stack in which a plurality of fuel cell units each having an anode and a cathode are provided and which generates electricity using a fuel gas and an oxidant gas, and a combustion unit which combusts anode off-gas and cathode off-gas discharged from the cell stack; a raw fuel supply unit that supplies raw fuel from outside the container to the hot module; an oxidant gas supply unit that supplies the oxidant gas from outside the container to the cell stack; a gas flow passage through which gas discharged from the hot module flows; a moisture recovery unit that recovers moisture contained in the gas flowing through the gas flow passage; A fuel cell system comprising: a temperature adjusting unit that adjusts the temperature of the gas flowing through the gas flow passage, the temperature adjusting unit being located downstream of the hot module and upstream of the moisture recovery unit in the gas flow direction; a housing that houses the hot module, the raw fuel supply unit, the oxidant gas supply unit, the gas flow channel, the moisture recovery unit, and the temperature adjustment unit, the temperature adjustment unit includes a first flow path, a second flow path having a higher heat dissipation performance than the first flow path, and a flow rate adjustment unit capable of adjusting a flow rate of the gas flowing through the first flow path and a flow rate of the gas flowing through the second flow path, The flow rate adjusting unit reduces the flow rate of the gas flowing through the first flow path and increases the flow rate of the gas flowing through the second flow path when the temperature inside the housing, which is affected by the outside air temperature, reaches or exceeds a predetermined temperature threshold.

2. 2. The fuel cell system according to claim 1, wherein the length of the second flow path is longer than the length of the first flow path.

3. 2. The fuel cell system according to claim 1, wherein the temperature adjusting unit further comprises a heat exchanger disposed in the second flow path and exchanging heat between the gas flowing through the second flow path and the refrigerant.

4. the hot module further includes a reforming unit that steam reforms the raw fuel to generate the fuel gas, and a fuel gas supply path that supplies the fuel gas from the reforming unit to the anode, the gas flow passage is a reflux gas flow passage that refluxes the reflux gas, which is the gas discharged from the reforming unit of the hot module, to the raw fuel supply unit, 4. The fuel cell system according to claim 1, wherein the reflux gas, whose temperature is adjusted by the temperature adjustment unit, flows through the reflux gas flow path, and from which moisture is recovered by the moisture recovery unit, is supplied to a desulfurizer that desulfurizes the raw fuel to be supplied to the reforming unit.

5. the gas flow passage is a combustion exhaust gas passage through which combustion exhaust gas generated in the combustion section is discharged from the container, 4. The fuel cell system according to claim 1, wherein the combustion exhaust gas, whose temperature has been adjusted by the temperature adjustment unit and which has flowed through the combustion exhaust gas passage, is supplied to the moisture recovery unit.

6. 2. The fuel cell system according to claim 1, wherein a temperature rise prevention material for preventing a temperature rise is applied or attached to an outer wall surface of the housing.

Images