Solid oxide fuel cell generator

Abstract

The present invention provides a solid oxide fuel cell generator that can suppress a decrease in power generation capacity of a solid oxide fuel cell while using a fuel gas containing sulfur without requiring a desulfurization device. A solid oxide fuel cell generator (11) includes a fuel cell section (26) of a solid oxide type that generates power using a fuel gas and an oxidizing gas; an oxidizing gas supply section (21) that supplies the oxidizing gas to the fuel cell section (26); an air electrode oxidizing gas supply path (16b) that introduces the oxidizing gas into an air electrode (13b) of the fuel cell section (26); a fuel electrode oxidizing gas supply path (16a) that introduces the oxidizing gas into a fuel electrode (13a) of the fuel cell section (26); a fuel gas supply path (15) that introduces the fuel gas stored in a gas container (12) into the fuel cell section (26); a heating mechanism (17) that heats the fuel cell section (26) using the fuel gas; and a control section (58) that performs control to supply the oxidizing gas and the fuel gas to the fuel electrode (13a) at a prescribed ratio.

Description

Technical Field

[0001] The present invention relates to a power generator including a solid oxide fuel cell (SOFC). Background Art

[0002] Solid oxide fuel cells (SOFCs) generate electricity through an electrochemical reaction between continuously supplied fuel gas (hydrogen (H2) and carbon monoxide (CO)) and an oxidizing gas (a mixed gas containing oxygen (O2), such as air). The fuel cell section that generates electricity has an anode (fuel electrode) and a cathode (air electrode). The anode is connected to a fuel gas supply line for the fuel gas. The cathode is connected to an oxidizing gas supply line for the oxidizing gas.

[0003] Patent Document 1 discloses a solid oxide fuel cell power generation system comprising a solid oxide fuel cell unit, a desulfurization device, and a reformer. The solid oxide fuel cell power generation system described in Patent Document 1 utilizes a hydrocarbon fuel (cartridge gas) such as butane gas, primarily filled in a gas container, as fuel gas.

[0004] Here, fossil fuel gases such as box gas, city gas, and LPG (liquefied petroleum gas) contain sulfur components as odorants. The sulfur components can have an adverse effect on the cells of the solid oxide fuel cell. For example, the sulfur components contained in the fuel gas adhere to the cells of the solid oxide fuel cell, causing carbon to precipitate in the cells of the solid oxide fuel cell. When carbon precipitates in the cells of the solid oxide fuel cell, the carbon will hinder the chemical reaction between the cells and the fuel gas, making it impossible to fully generate electricity, and the power generation capacity of the solid oxide fuel cell is reduced. Therefore, as in the solid oxide fuel cell power generation system described in Patent Document 1, a generator equipped with a solid oxide fuel cell generally has a desulfurization device that removes sulfur components from the fuel gas. In addition, the reformer reforms the fuel gas from which the sulfur components have been removed by the desulfurization device into hydrogen (H2) and carbon monoxide (CO), etc., and then supplies hydrogen (H2) and carbon monoxide (CO) to the anode of the fuel cell unit.

[0005] However, if a desulfurization device and a reformer are provided, the generator equipped with a solid oxide fuel cell will become complicated and large-scale. In addition, the desulfurization device and the reformer need to be maintained. Therefore, there is room for improvement in that it becomes difficult to transport a generator equipped with a solid oxide fuel cell. It is expected that a generator equipped with a solid oxide fuel cell will have the ability to generate the electricity required for charging electrical products such as smartphones and tablet terminals, or for using electrical products such as LED (Light Emitting Diode) lighting, outdoors where commercial power is not supplied and at disaster sites.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2017-27766 Summary of the Invention

[0009] Technical problem to be solved by the invention

[0010] The present invention has been made to solve the above-mentioned technical problems, and its object is to provide a solid oxide fuel cell generator that can suppress the reduction in the power generation capacity of the solid oxide fuel cell while using sulfur-containing fuel gas without requiring a desulfurization device.

[0011] Technical solutions to technical problems

[0012] The technical problem can be solved by the solid oxide fuel cell generator involved in the present invention, which is characterized in that it comprises: a solid oxide fuel cell unit that generates electricity by using fuel gas and oxidizing gas; an oxidizing gas supply unit that transports the oxidizing gas to the fuel cell unit; an oxidizing gas supply path for the air electrode that introduces the oxidizing gas transported from the oxidizing gas supply unit into the air electrode of the fuel cell unit; an oxidizing gas supply path for the fuel electrode that introduces the oxidizing gas transported from the oxidizing gas supply unit into the fuel electrode of the fuel cell unit; a fuel gas supply path that introduces the fuel gas contained in a gas container into the fuel cell unit; a heating mechanism that heats the fuel cell unit by using the fuel gas introduced by the fuel gas supply path; and a control unit that controls the supply of the oxidizing gas introduced through the oxidizing gas supply path for the fuel electrode and the fuel gas introduced through the fuel gas supply path to the fuel electrode at a specified ratio.

[0013] According to the solid oxide fuel cell generator of the present invention, the control unit supplies oxidizing gas introduced through the fuel electrode oxidizing gas supply path and fuel gas introduced through the fuel gas supply path to the fuel electrode at a predetermined ratio. Therefore, for example, the control unit can dilute the fuel gas with oxidizing gas to suppress the concentration of sulfur components in the fuel gas to below a predetermined concentration, and then supply the fuel gas containing sulfur components below the predetermined concentration to the fuel electrode of the fuel cell unit. Alternatively, for example, the control unit can dilute the fuel gas with oxidizing gas to suppress the concentration of sulfur components in the fuel gas to below an extremely low concentration, and then purge the fuel electrode of the fuel cell unit with the oxidizing gas. This can prevent sulfur components in the fuel gas from adhering to the cells of the solid oxide fuel cell unit. This can prevent carbon deposition in the cells of the solid oxide fuel cell unit, and can prevent the chemical reaction between the cells of the fuel cell unit and the fuel gas from being hindered by carbon. Thus, the solid oxide fuel cell generator of the present invention can suppress the reduction in the power generation capacity of the solid oxide fuel cell unit while using sulfur-containing fuel gas, even without requiring a desulfurization device. Furthermore, since a desulfurization device is no longer required, the solid oxide fuel cell generator can be made smaller, lighter, and maintenance-free, thereby providing a mobile solid oxide fuel cell generator.

[0014] In the solid oxide fuel cell generator involved in the present invention, it is preferably characterized in that the control unit performs the following control at specified intervals: stops the supply of the fuel gas introduced through the fuel gas supply path, and only supplies the oxidizing gas introduced through the fuel electrode oxidizing gas supply path to the fuel electrode.

[0015] According to the solid oxide fuel cell generator of the present invention, the control unit stops the supply of fuel gas introduced through the fuel gas supply path at predetermined intervals and supplies only the oxidizing gas introduced through the fuel electrode oxidizing gas supply path to the fuel electrode. This allows the control unit to purge the fuel electrode of the fuel cell unit with oxidizing gas at predetermined intervals. For example, the control unit can periodically purge the fuel electrode of the fuel cell unit with oxidizing gas before the sulfur components contained in the fuel gas adhere to or accumulate on the cells of the solid oxide fuel cell unit. This can further suppress the sulfur components contained in the fuel gas from adhering to the cells of the solid oxide fuel cell unit. This can further suppress the precipitation of carbon in the cells of the solid oxide fuel cell unit, and further suppress the chemical reaction between the cells of the fuel cell unit and the fuel gas from being hindered by carbon. Thus, the solid oxide fuel cell generator of the present invention can further suppress the reduction in the power generation capacity of the solid oxide fuel cell unit while using sulfur-containing fuel gas, even without requiring a desulfurization device.

[0016] In the solid oxide fuel cell generator involved in the present invention, it is preferably characterized in that the control unit receives the electric power generated by the fuel cell unit, and based on information related to the electric power, executes control to stop the supply of the fuel gas introduced through the fuel gas supply path, and only supplies the oxidizing gas introduced through the oxidizing gas supply path for the fuel electrode to the fuel electrode.

[0017] According to the solid oxide fuel cell generator of the present invention, the control unit receives the power generated by the fuel cell unit and, based on information related to the power, stops the supply of fuel gas introduced through the fuel gas supply path and supplies only the oxidizing gas introduced through the fuel electrode oxidizing gas supply path to the fuel electrode. This allows the control unit to purge the fuel electrode of the fuel cell unit with oxidizing gas based on information related to the power generated by the fuel cell unit. For example, the control unit can purge the fuel electrode of the fuel cell unit with oxidizing gas based on the amount of power generated by the fuel cell unit, the rate of decrease in the amount of power generated by the fuel cell unit relative to the initial power, and so on. This further suppresses the sulfur component contained in the fuel gas from adhering to the cells of the solid oxide fuel cell unit. This further suppresses the precipitation of carbon in the cells of the solid oxide fuel cell unit, and further suppresses the chemical reaction between the cells of the fuel cell unit and the fuel gas from being hindered by carbon. Thus, the solid oxide fuel cell generator of the present invention can further suppress the reduction in the power generation capacity of the solid oxide fuel cell unit while using sulfur-containing fuel gas, even without requiring a desulfurization device.

[0018] The solid oxide fuel cell generator involved in the present invention is preferably characterized in that it also has a branch valve, which is connected to the oxidation gas supply path for the fuel electrode and the fuel gas supply path, and can switch between a state in which both the oxidation gas and the fuel gas are introduced into the fuel electrode and a state in which only the oxidation gas is introduced into the fuel electrode, and the control unit adjusts the ratio by controlling the branch valve.

[0019] According to the solid oxide fuel cell generator of the present invention, the controller can adjust the ratio of oxidant gas to fuel gas supplied to the fuel cell section by controlling a branch valve connected to the fuel electrode oxidant gas supply line and the fuel gas supply line. In other words, the controller can easily adjust the ratio of oxidant gas to fuel gas supplied to the fuel cell section by controlling a single branch valve. This makes it easier to adjust the ratio of oxidant gas to fuel gas using a single branch valve, compared to using separate valves in the fuel electrode oxidant gas supply line and the fuel gas supply line. Furthermore, it is possible to omit auxiliary equipment such as a desulfurizer and a reformer, further reducing the size and weight of the solid oxide fuel cell generator.

[0020] Effects of the Invention

[0021] According to the present invention, a solid oxide fuel cell power generator can be provided that can suppress a decrease in the power generation capacity of the solid oxide fuel cell while using a sulfur-containing fuel gas without requiring a desulfurization device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a perspective view showing a solid oxide fuel cell generator according to an embodiment of the present invention.

[0023] Figure 2 This is a block diagram showing the main configuration of the solid oxide fuel cell generator according to this embodiment.

[0024] Figure 3 This is a block diagram illustrating a specific example of the configuration of the main parts of the solid oxide fuel cell generator according to this embodiment.

[0025] Figure 4 This is a table showing the test conditions performed by the present inventors.

[0026] Figure 5 This is a graph showing an example of the results of tests conducted using fuel gas containing an odorant and fuel gas not containing an odorant.

[0027] Figure 6 This is a graph showing an example of the results of tests performed when the anode is purged with an oxidizing gas and when the anode is not purged with an oxidizing gas. DETAILED DESCRIPTION

[0028] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0029] It should be noted that the embodiments described below are preferred specific examples of the present invention, and therefore various technically preferred limitations are added. However, the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description. In addition, in each of the drawings, the same reference numerals are attached to the same components, and detailed descriptions are omitted as appropriate.

[0030] Figure 1 It is a perspective view showing a solid oxide fuel cell generator according to an embodiment of the present invention.

[0031] Figure 2 This is a block diagram showing the main configuration of the solid oxide fuel cell generator according to this embodiment.

[0032] Figure 3This is a block diagram illustrating a specific example of the configuration of the main parts of the solid oxide fuel cell generator according to this embodiment.

[0033] The solid oxide fuel cell generator 11 according to this embodiment utilizes a gas container 12 filled with a fuel gas (hydrocarbon fuel) primarily composed of butane gas, and can be moved to a desired location to generate electricity whenever power is needed. In other words, the solid oxide fuel cell generator 11 according to this embodiment is a mobile generator that utilizes the fuel gas contained in the gas container 12 and can be used outdoors or at disaster sites, where commercial power is unavailable. The hydrocarbon fuel primarily composed of butane gas, contained in the gas container 12, contains sulfur as an odorant.

[0034] like Figures 1 to 3 As shown, the solid oxide fuel cell generator 11 involved in this embodiment includes a fuel cell unit 26, an oxidizing gas supply unit 21, an oxidizing gas supply path 16, an oxidizing gas supply path 16a for the fuel electrode, an oxidizing gas supply path 16b for the air electrode, a fuel gas supply path 15, a burner 17 and a control unit 58. The solid oxide fuel cell generator 11 may also include a thermoelectric power generation unit 61. In the description of this embodiment, the case where the solid oxide fuel cell generator 11 includes the thermoelectric power generation unit 61 is taken as an example. In addition, the thermoelectric power generation unit 61 does not necessarily have to be provided. As Figure 1 As shown, the fuel cell unit 26 , the oxidizing gas supply unit 21 , the burner 17 , the thermoelectric power generation unit 61 , and the control unit 58 are provided on a housing 63 .

[0035] The fuel cell unit 26 is a solid oxide fuel cell unit that generates electricity using fuel gas and oxidizing gas. Specifically, the fuel cell unit 26 comprises a solid oxide fuel cell (SOFC) that generates electricity through an electrochemical reaction between the fuel gas (hydrogen (H2) and carbon monoxide (CO)) and the oxidizing gas (a mixed gas containing oxygen (O2) such as air).

[0036] The fuel cell unit 26 has a plurality of battery modules. Figure 1 As shown, the fuel cell unit 26 of this embodiment includes a first battery module 27a, a second battery module 27b, a third battery module 27c, and a fourth battery module 27d. A battery module is also referred to as a battery stack. It should be noted that the number of battery modules in the fuel cell unit 26 is not limited to four and can be three or fewer, or five or more. In the description of this embodiment, the case where the fuel cell unit 26 includes four battery modules 27a, 27b, 27c, and 27d is used as an example.

[0037] like Figure 2As shown, each battery module 27a, 27b, 27c, and 27d has a plurality of batteries 13 as the minimum unit of the fuel cell section 26. The battery 13 of the fuel cell section 26 has an anode (fuel electrode) 13a where an oxidation reaction occurs, a cathode (air electrode) 13b where a reduction reaction occurs, and an electrolyte 13c that serves as an ion conductor. The anode 13a of this embodiment is an example of a "fuel electrode" of the present invention. The cathode 13b of this embodiment is an example of an "air electrode" of the present invention. The anode 13a is connected to the fuel electrode oxidation gas supply path 16a and the fuel gas supply path 15 via the mixed gas supply path 28 and the branch valve 65. The cathode 13b is connected to the air electrode oxidation gas supply path 16b. In the anode 13a, at least one of hydrogen (H2) and carbon monoxide (CO) is used as fuel. In the cathode 13b, air (oxygen) is used as an oxidant.

[0038] The oxidizing gas supply unit 21 is connected to the oxidizing gas supply path 16. The oxidizing gas supply path 16 branches into a fuel electrode oxidizing gas supply path 16a and an air electrode oxidizing gas supply path 16b downstream of the heat exchanger 23. The oxidizing gas supply unit 21 supplies oxidizing gas to the anode 13a of the fuel cell unit 26 via the oxidizing gas supply path 16, the fuel electrode oxidizing gas supply path 16a, and the mixed gas supply path 28. Furthermore, the oxidizing gas supply unit 21 supplies oxidizing gas to the cathode 13b of the fuel cell unit 26 via the oxidizing gas supply path 16 and the air electrode oxidizing gas supply path 16b.

[0039] For example, the oxidizing gas supply unit 21 includes a plurality of blowers. Figure 3 As shown, the oxidizing gas supply unit 21 of this embodiment includes a first blower 21a and a second blower 21b. The first blower 21a delivers oxidizing gas to the anode 13a of the fuel cell unit 26 through the oxidizing gas supply path 16, the fuel electrode oxidizing gas supply path 16a, and the mixed gas supply path 28. The second blower 21b delivers oxidizing gas to the cathode 13b of the fuel cell unit 26 through the oxidizing gas supply path 16 and the air electrode oxidizing gas supply path 16b. Examples of the first blower 21a and the second blower 21b include an air pump and a fan. It should be noted that the number of blowers included in the oxidizing gas supply unit 21 is not limited to two, and may be one or more than three.

[0040] The oxidizing gas supply path 16 is connected to the oxidizing gas supply unit 21 and directs the oxidizing gas delivered from the oxidizing gas supply unit 21 to the fuel cell unit 26. As previously described, the oxidizing gas supply path 16 branches into the fuel electrode oxidizing gas supply path 16a and the air electrode oxidizing gas supply path 16b downstream of the heat exchanger 23. The fuel electrode oxidizing gas supply path 16a is connected to the anode 13a of the fuel cell unit 26 via the branching valve 65 and the mixed gas supply path 28. The air electrode oxidizing gas supply path 16b is connected to the cathode 13b of the fuel cell unit 26.

[0041] The gas container 12 is a box-type gas cylinder containing compressed liquefied gas, for example, and contains fuel gas. The fuel gas ejected from the gas container 12 enters the container connection portion 64 (see Figure 1 ) to adjust the pressure. It should be noted that if the gas container 12 is a cassette-type gas cylinder, the attachment and detachment mechanism between the gas container 12 and the container connection 64 is a magnet-type mechanism. Therefore, if the gas cylinder is heated and the internal pressure of the cylinder abnormally rises, the safety mechanism activates, disconnecting the gas container 12 from the container connection 64.

[0042] The fuel gas supply path 15 is a flow path connected to the container connection portion 64, and introduces the fuel gas such as butane gas filled in the gas container 12 into the anode 13a of the fuel cell unit 26. Specifically, Figure 2 as well as Figure 3 As shown, the fuel gas supply path 15 introduces fuel gas to the anode 13a of the fuel cell unit 26 via the mixed gas supply path 28 connected via the branch valve 65. The hydrocarbon fuel mainly composed of butane gas or the like contained in the gas container 12 contains sulfur as an odorant.

[0043] The burner 17 burns the fuel gas (hydrocarbon fuel) supplied from the gas container 12 through the fuel gas supply path 15 to heat the fuel cell unit 26 to the power generation start temperature. Figure 2 as well as Figure 3 As shown, the burner fuel supply path 22 branches off from the fuel gas supply path 15 and is connected to the burner 17. The fuel gas supplied from the gas container 12 via the container connection portion 64 passes through the fuel gas supply path 15, the burner fuel supply path 22, and a gas-air mixer (not shown), and is introduced into the burner 17 while being mixed with air.

[0044] An electrode (not shown) is provided near burner 17. When the user rotates the operating knob (not shown), an igniter (not shown) is pressed, generating a pulse voltage. The pulse voltage generated by the rotation of the operating knob causes the electrode provided near burner 17 to discharge, causing the fuel gas supplied from gas container 12 to burner 17 to combust, thereby igniting burner 17. Burner 17 in this embodiment is an example of the "heating mechanism" of the present invention.

[0045] The thermoelectric power generation section 61 includes a high-temperature section 61a, a low-temperature section 61b, and a thermoelectric element 61c, and is heated by the burner 17. Specifically, the high-temperature section 61a is disposed, for example, opposite the fuel cell section 26, and is heated by the flame emitted from the burner 17 and the heat transferred from the exhaust gas. The high-temperature section 61a functions as a heat receiving section, effectively receiving the heat transferred from the flame emitted from the burner 17 and the exhaust gas, and transferring it to the thermoelectric element 61c. The low-temperature section 61b is disposed separately from the high-temperature section 61a via the thermoelectric element 61c. The low-temperature section 61b is disposed opposite the high-temperature section 61a and is maintained at a lower temperature than the high-temperature section 61a. The cooling method of the low-temperature section 61b is not particularly limited, and may be, for example, natural air cooling or forced air cooling.

[0046] Thermoelectric element 61c is sandwiched between high-temperature portion 61a and low-temperature portion 61b, generating electricity based on the temperature difference between these two portions. Thermoelectric element 61c utilizes the Seebeck effect to generate thermoelectromotive force. Thermoelectric elements are also known as thermoelectric conversion elements or thermoelectric generating elements. When the temperature difference between high-temperature portion 61a and low-temperature portion 61b is approximately 100°C to 150°C, for example, the thermoelectric element 61c can generate a greater amount of thermoelectromotive force.

[0047] like Figure 2 As shown, exhaust path 19 is connected to fuel cell section 26. Exhaust path 19 is a flow path that discharges high-temperature exhaust gas from fuel cell section 26 to the outside of solid oxide fuel cell generator 11. A CO remover 18 is provided in exhaust path 19. CO remover 18 removes CO from exhaust gas at a temperature of 200°C or higher using a catalyst installed inside.

[0048] In addition, if Figure 2 As shown, heat exchangers 23 are provided in the oxidizing gas supply path 16 and the exhaust path 19. The heat exchangers 23 perform heat exchange between the oxidizing gas supply path 16 and the exhaust path 19. The solid oxide fuel cell generator 11 according to this embodiment is provided with two heat exchangers 23: a low-temperature side heat exchanger 23a and a high-temperature side heat exchanger 23b.

[0049] The oxidizing gas supplied from the oxidizing gas supply unit 21 to the oxidizing gas supply path 16 passes through the low-temperature side heat exchanger 23a, where it exchanges heat with the exhaust gas flowing through the exhaust path 19 in the low-temperature side heat exchanger 23a, raising its temperature. The oxidizing gas, having passed through the low-temperature side heat exchanger 23a, then exchanges heat with the exhaust gas flowing through the exhaust path 19 in the high-temperature side heat exchanger 23b, further raising its temperature. The oxidizing gas, having been heated by the low-temperature and high-temperature side heat exchangers 23a and 23b, is then introduced to the anode 13a via the fuel electrode oxidizing gas supply path 16a and to the cathode 13b via the air electrode oxidizing gas supply path 16b.

[0050] The high-temperature exhaust gas generated by power generation in the fuel cell section 26 passes through the high-temperature side heat exchanger 23b, where it exchanges heat with the oxidant gas flowing through the oxidant gas supply path 16 in the high-temperature side heat exchanger 23b, thereby lowering its temperature. The temperature of the exhaust gas discharged from the fuel cell section 26 and before passing through the high-temperature side heat exchanger 23b is, for example, approximately 600°C or higher. The temperature of the exhaust gas, lowered by the high-temperature side heat exchanger 23b, is, for example, approximately 200°C or higher. This allows the catalyst in the CO remover 18 to more reliably act on the exhaust gas. Next, the exhaust gas passing through the high-temperature side heat exchanger 23b passes through the CO remover 18 and the low-temperature side heat exchanger 23a, where it exchanges heat with the oxidant gas flowing through the oxidant gas supply path 16 in the low-temperature side heat exchanger 23a, further lowering its temperature. The temperature of the exhaust gas lowered by the low-temperature side heat exchanger 23a is, for example, less than approximately 80°C. The exhaust gas, having been cooled by the high-temperature side heat exchanger 23b and the low-temperature side heat exchanger 23a, is then discharged from the outlet of the exhaust path 19.

[0051] The branch valve 65 is connected to the fuel electrode oxidizing gas supply path 16a and the fuel gas supply path 15. In other words, the branch valve 65 interconnects the fuel electrode oxidizing gas supply path 16a and the fuel gas supply path 15. The branch valve 65 is a so-called three-way valve that can switch between a state in which both the oxidizing gas introduced through the fuel electrode oxidizing gas supply path 16a and the fuel gas introduced through the fuel gas supply path 15 are introduced into the anode 13a, a state in which only the oxidizing gas introduced through the fuel electrode oxidizing gas supply path 16a is introduced into the anode 13a, and a state in which only the fuel gas introduced through the fuel gas supply path 15 is introduced into the anode 13a.

[0052] The control unit 58 controls the overall operation of the solid oxide fuel cell generator 11 according to this embodiment. Figure 2 as well as Figure 3As shown, the control section 58 receives electric power generated by the fuel cell section 26 and the thermoelectric power generation section 61, and supplies the electric power to the oxidizing gas supply section 21. In addition, the control section 58 receives electric power generated by the fuel cell section 26 and the thermoelectric power generation section 61, and controls the operation of the branch valve 65 on the basis of information related to the electric power. Details will be described later. In addition, the control section 58 has the electric power conversion device 54. The electric power conversion device 54 receives electric power generated by the fuel cell section 26, and converts direct current electric power into alternating current electric power.

[0053] Here, as described above, the fuel gas (hydrocarbon fuel) mainly of butane gas or the like, which is stored in the gas container 12, contains a sulfur component as a flavoring agent. The sulfur component adversely affects the cells 13 of the fuel cell section 26. For example, the sulfur component contained in the fuel gas adheres to the cells 13 of the fuel cell section 26, and causes carbon to be deposited in the cells 13 of the fuel cell section 26. When carbon is deposited in the cells 13 of the fuel cell section 26, the carbon hinders the chemical reaction of the cells 13 of the fuel cell section 26 with the fuel gas, and the cells 13 of the fuel cell section 26 cannot generate electric power sufficiently, and the electric power generation capability of the fuel cell section 26 is reduced. Therefore, a power generator provided with a solid oxide fuel cell generally has a desulfurization device that removes the sulfur component from the fuel gas. In addition, a reformer provided on the downstream side of the desulfurization device reforms the fuel gas from which the sulfur component has been removed by the desulfurization device into hydrogen (H2) and carbon monoxide (CO) or the like, and then supplies the hydrogen (H2) and the carbon monoxide (CO) to the anode of the fuel cell section.

[0054] However, if the desulfurization device and the reformer are provided, the power generator provided with the solid oxide fuel cell becomes complicated and large. In addition, the desulfurization device and the reformer need to be maintained. Therefore, it is difficult to transport the power generator provided with the solid oxide fuel cell.

[0055] In contrast, the control section 58 of the solid oxide fuel cell power generator 11 according to the present embodiment performs control to supply the oxidizing gas introduced through the fuel electrode oxidizing gas supply path 16a and the fuel gas introduced through the fuel gas supply path 15 to the anode 13a of the fuel cell section 26 at a prescribed ratio. Specifically, the control section 58 controls the opening degree of the branch valve 65 to supply the oxidizing gas introduced through the fuel electrode oxidizing gas supply path 16a and the fuel gas introduced through the fuel gas supply path 15 to the anode 13a of the fuel cell section 26 at a prescribed ratio through the mixed gas supply path 28. In the present specification, the "prescribed ratio" includes not only the ratio at which the oxidizing gas and the fuel gas are mixed, but also the ratio when only the oxidizing gas is contained (100% of the oxidizing gas) and the ratio when only the fuel gas is contained (100% of the fuel gas).

[0056] According to the solid oxide fuel cell generator 11 of this embodiment, for example, the controller 58 can dilute the fuel gas with an oxidizing gas to suppress the concentration of sulfur components in the fuel gas to a predetermined concentration or below, and then supply the fuel gas containing sulfur components at a predetermined concentration or below to the anode 13a of the fuel cell section 26. Alternatively, for example, the controller 58 can dilute the fuel gas with an oxidizing gas to suppress the concentration of sulfur components in the fuel gas to an extremely low concentration or below, and then purge the anode 13a of the fuel cell section 26 with the oxidizing gas. This can prevent the sulfur components in the fuel gas from adhering to the cells 13 of the fuel cell section 26. This can also prevent carbon from precipitating in the cells 13 of the fuel cell section 26, and prevent the chemical reaction between the cells 13 of the fuel cell section 26 and the fuel gas from being hindered by carbon. Thus, the solid oxide fuel cell generator 11 of this embodiment can use sulfur-containing fuel gas while suppressing a decrease in the power generation capacity of the fuel cell section 26, even without requiring a desulfurization device. Furthermore, since a desulfurization device is no longer required, the solid oxide fuel cell generator 11 can be made smaller, lighter, and maintenance-free. Thus, a mobile solid oxide fuel cell generator 11 can be provided.

[0057] Describing the operation of the solid oxide fuel cell generator 11 according to this embodiment in more detail, the controller 58 controls the opening of the branch valve 65 to dilute the fuel gas introduced through the fuel gas supply line 15 with the oxidizing gas introduced through the fuel electrode oxidizing gas supply line 16a, thereby adjusting the ratio of oxidizing gas to fuel gas supplied to the anode 13a. According to findings obtained by the present inventors, the concentration of the fuel gas diluted with the oxidizing gas is preferably 20% or less, and more preferably 7% or less.

[0058] This reduces the concentration of sulfur in the fuel gas. This prevents the sulfur in the fuel gas from adhering to the cells 13 of the fuel cell section 26. This prevents carbon from precipitating in the cells 13 of the fuel cell section 26, and prevents the chemical reaction between the cells 13 of the fuel cell section 26 and the fuel gas from being impeded by carbon. Thus, the solid oxide fuel cell generator 11 according to this embodiment can suppress a decrease in the power generation capacity of the fuel cell section 26 while using sulfur-containing fuel gas, even without requiring a desulfurization device.

[0059] Alternatively, the controller 58 controls the opening of the branch valve 65 at predetermined intervals to stop the supply of the fuel gas introduced through the fuel gas supply path 15 and supply only the oxidizing gas introduced through the fuel electrode oxidizing gas supply path 16a to the anode 13a.

[0060] Thus, the control section 58 can purge the anode 13a of the fuel cell section 26 with the oxidizing gas at regular intervals. For example, the control section 58 can periodically purge the anode 13a of the fuel cell section 26 with the oxidizing gas before sulfur components contained in the fuel gas adhere or accumulate on the cells 13 of the fuel cell section 26. Thus, the sulfur components contained in the fuel gas can be further inhibited from adhering to the cells 13 of the fuel cell section 26. Thus, the carbon can be further inhibited from being deposited in the cells 13 of the fuel cell section 26, and the chemical reaction of the cells 13 of the fuel cell section 26 with the fuel gas can be inhibited from being hindered by the carbon. Thus, the solid oxide fuel cell generator 11 according to the present embodiment can further inhibit the power generation capability of the fuel cell section 26 from decreasing while using the fuel gas containing sulfur, even without a desulfurization device.

[0061] Further, the control section 58 receives electric power generated by the fuel cell section 26, and controls the opening degree of the branch valve 65 based on information related to the electric power. Then, the control section 58 stops the supply of the fuel gas introduced through the fuel gas supply path 15, and supplies only the oxidizing gas introduced through the fuel electrode oxidizing gas supply path 16a to the anode 13a.

[0062] Thus, the control section 58 can purge the anode 13a of the fuel cell section 26 with the oxidizing gas based on information related to the electric power generated by the fuel cell section 26. For example, the control section 58 can purge the anode 13a of the fuel cell section 26 with the oxidizing gas based on the amount of electric power generated by the fuel cell section 26, the rate of decrease of the amount of electric power generated by the fuel cell section 26 from the initial amount of electric power, or the like. Thus, the sulfur components contained in the fuel gas can be further inhibited from adhering to the cells 13 of the fuel cell section 26. Thus, the carbon can be further inhibited from being deposited in the cells 13 of the fuel cell section 26, and the chemical reaction of the cells 13 of the fuel cell section 26 with the fuel gas can be inhibited from being hindered by the carbon. Thus, the solid oxide fuel cell generator 11 according to the present embodiment can further inhibit the power generation capability of the fuel cell section 26 from decreasing while using the fuel gas containing sulfur, even without a desulfurization device.

[0063] Further, as described above, the control section 58 can easily adjust the ratio of the oxidizing gas and the fuel gas supplied to the fuel cell section 26 by controlling the branch valve 65. Thus, compared to a case where a valve is provided on each of the fuel electrode oxidizing gas supply path 16a and the fuel gas supply path 15, the ratio of the oxidizing gas and the fuel gas can be easily adjusted with one branch valve 65, and at the same time, a desulfurization device and auxiliary equipment such as a reformer can be omitted, and further miniaturization and weight reduction of the solid oxide fuel cell generator 11 can be achieved.

[0064] Furthermore, the solid oxide fuel cell generator 11 according to this embodiment can combine power generation by the fuel cell section 26 with power generation by the thermoelectric generation section 61. Specifically, the power generated by the thermoelectric elements 61c of the thermoelectric generation section 61 can be used to supplement a portion of the required power generated by the high-temperature operation of the fuel cell section 26. Therefore, compared to a case where the fuel cell section 26 generates the same amount of power alone, the overall power generation of the solid oxide fuel cell generator 11 can be increased by the supplementary amount of power generated by the thermoelectric elements 61c of the thermoelectric generation section 61, while also reducing fuel gas usage and conserving fuel gas. Furthermore, compared to a case where the fuel cell section 26 generates power alone, the operating temperature of the fuel cell section 26 can be stably maintained at approximately 650±50°C. This improves the durability of the fuel cell section 26 and minimizes the effects of heat on peripheral components of the fuel cell section 26. Furthermore, this increases the range of materials available for peripheral components of the fuel cell section 26.

[0065] It should be noted that in this embodiment, the branch valve 65 is provided at the connection portion between the fuel electrode oxidizing gas supply path 16a and the fuel gas supply path 15. However, the branch valve 65 does not necessarily need to be provided. For example, the fuel electrode oxidizing gas supply path 16a and the fuel gas supply path 15 may be connected to the anode 13a of the fuel cell unit 26 via different paths. In addition, for example, the control unit 58 may adjust the amount of oxidizing gas by controlling the oxidizing gas supply unit 21 or controlling a solenoid valve provided on the oxidizing gas supply path 16 or the fuel electrode oxidizing gas supply path 16a, and simultaneously adjust the amount of fuel gas by controlling a solenoid valve provided on the fuel gas supply path 15, thereby supplying oxidizing gas and fuel gas to the anode 13a of the fuel cell unit 26 at a specified ratio. In addition, a branch valve (i.e., a three-way valve) may be provided at the branch portion where the oxidizing gas supply path 16 branches into the fuel electrode oxidizing gas supply path 16a and the air electrode oxidizing gas supply path 16b. Thus, the controller 58 can appropriately adjust the ratio of the oxidizing gas supplied to the anode 13a and the oxidizing gas supplied to the cathode 13b by controlling the opening of the branch valve provided at the branch portion between the fuel electrode oxidizing gas supply path 16a and the air electrode oxidizing gas supply path 16b.

[0066] Next, an example of the test results performed by the present inventors will be described with reference to the drawings.

[0067] Figure 4 This is a table showing the test conditions performed by the present inventors.

[0068] Figure 5 This is a graph showing an example of the results of tests conducted using fuel gas containing an odorant and fuel gas not containing an odorant.

[0069] Figure 6 This is a graph showing an example of the results of tests performed when the anode is purged with an oxidizing gas and when the anode is not purged with an oxidizing gas.

[0070] Figure 5 as well as Figure 6 The horizontal axis represents the operating time (hours) of the test device. Figure 5 as well as Figure 6 The vertical axis represents the decrease rate of the amount of electricity generated in the solid oxide fuel cell (SOFC) relative to the initial amount of electricity.

[0071] First, if Figure 4 As shown, the present inventors devised a solid oxide fuel cell generator 11 according to this embodiment and prepared a solid oxide fuel cell having a cell 13 with dimensions (effective power generation area) of 20 mm x 50 mm. The solid oxide fuel cell was then placed in an electric furnace at a furnace temperature of 690°C. Fuel gas containing 7% butane was supplied to the anode (fuel electrode) 13a at a flow rate of 96 ml / min, and oxidizing gas was supplied to the cathode (air electrode) 13b at a flow rate of 231 ml / min.

[0072] Next, the present inventors conducted experiments on fuel gas containing odorant (sulfur component) and fuel gas not containing odorant (sulfur component) in order to study the influence of sulfur component as odorant. Figure 5 As shown. That is, the absolute value of the slope of the approximate straight line (regression line) for the power reduction rate when a fuel gas containing sulfur components is supplied to the anode 13a is greater than the absolute value of the slope of the approximate straight line (regression line) for the power reduction rate when a fuel gas containing no sulfur components is supplied to the anode 13a. This shows that the power reduction rate when a fuel gas containing sulfur components is supplied to the anode 13a is greater than the power reduction rate when a fuel gas containing no sulfur components is supplied to the anode 13a. In addition, according to the present inventors' visual observation of the battery 13, after 80 hours of operation, carbon deposition was confirmed in the battery 13 when a fuel gas containing sulfur components was supplied to the anode 13a. On the other hand, no carbon deposition was confirmed in the battery 13 when a fuel gas containing no sulfur components was supplied to the anode 13a.

[0073] Based on the above test results, the present inventors believe that the sulfur component as an odorant adheres to the cell 13, and carbon is precipitated in the cell 13 starting from this sulfur component, thereby causing the power generated in the solid oxide fuel cell (SOFC) to decrease with the passage of operation time.

[0074] Therefore, the present inventors conducted experiments in which fuel gas containing sulfur was supplied to the anode 13a and the anode 13a was purged with oxidizing gas for 10 minutes every two hours, and in which the anode 13a was not purged with oxidizing gas. Figure 6 That is, it can be seen that the power reduction rate when the anode 13a is purged with oxidizing gas for a predetermined time (10 minutes in this test) every predetermined time (2 hours in this test) is smaller than the power reduction rate when the anode 13a is not purged with oxidizing gas. In particular, it can be seen that when the operation time has passed 80 hours ( Figure 6 The power reduction rate in the case where the anode 13a is purged with the oxidizing gas is improved compared to the case where the anode 13a is not purged with the oxidizing gas (see the portion indicated by arrow A1).

[0075] It should be noted that in this test, the anode 13a was purged with oxidizing gas for 10 minutes every two hours of operation, but as mentioned above, Figures 1 to 3 As described above, the anode 13a may be purged with the oxidizing gas based on information related to the power generated by the solid oxide fuel cell. For example, the rate of decrease of the power generated by the solid oxide fuel cell relative to the initial power, i.e. Figure 6 When the power reduction rate shown is below a predetermined threshold, the anode 13a may be purged with oxidizing gas. In this case, it is also expected that the power reduction rate when the anode 13a is purged with oxidizing gas will be improved compared to the power reduction rate when the anode 13a is not purged with oxidizing gas.

[0076] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments and can be modified in various ways without departing from the scope of the claims. The structures of the above embodiments can be partially omitted or can be arbitrarily combined in a manner different from that described above.

[0077] Description of Reference Numerals

[0078] 11: Solid oxide fuel cell generator; 12: Gas container; 13: Battery; 13a: Anode; 13b: Cathode; 13c: Electrolyte; 15: Fuel gas supply path; 16: Oxidizing gas supply path; 16a: Oxidizing gas supply path for fuel electrode; 16b: Oxidizing gas supply path for air electrode; 17: Burner; 18: CO remover; 19: Exhaust path; 21: Oxidizing gas supply unit; 21a: First blower; 21b: Second blower; 22: Burner fuel supply 1: a heat exchanger; 23a: a heat exchanger on the low-temperature side; 23b: a heat exchanger on the high-temperature side; 26: a fuel cell unit; 27a: a first battery module; 27b: a second battery module; 27c: a third battery module; 27d: a fourth battery module; 28: a mixed gas supply path; 54: a power conversion device; 58: a control unit; 61: a thermoelectric power generation unit; 61a: a high-temperature unit; 61b: a low-temperature unit; 61c: a thermoelectric element; 63: a frame; 64: a container connection unit; 65: a branch valve.

Claims

1. A solid oxide fuel cell generator, characterized in that: The solid oxide fuel cell generator comprises: A solid oxide fuel cell unit generates electricity using a fuel gas containing sulfur and an oxidizing gas. an oxidizing gas supply unit for supplying the oxidizing gas to the fuel cell unit; an air electrode oxidizing gas supply path for introducing the oxidizing gas fed from the oxidizing gas supply portion into the air electrode of the fuel cell portion; a fuel electrode oxidizing gas supply path for introducing the oxidizing gas fed from the oxidizing gas supply portion into the fuel electrode of the fuel cell portion; a fuel gas supply path for introducing the fuel gas contained in a gas container into the fuel cell unit; a heating mechanism for heating the fuel cell unit using the fuel gas introduced through the fuel gas supply path; and a control unit for controlling the supply of the oxidizing gas introduced through the oxidizing gas supply passage for the fuel electrode and the fuel gas introduced through the fuel gas supply passage to the fuel electrode at a predetermined ratio; The control unit performs the following control at prescribed intervals: stops supplying the fuel gas introduced through the fuel gas supply path, supplies only the oxidizing gas introduced through the fuel electrode oxidizing gas supply path to the fuel electrode, and dilutes the fuel gas with the oxidizing gas through the control unit, so that the solid oxide fuel cell generator becomes a structure that reduces the concentration of the sulfur component in the fuel gas without reducing the power generation capacity of the fuel cell unit.

2. The solid oxide fuel cell generator according to claim 1, characterized in that: The control unit receives the power generated by the fuel cell unit and performs the following control based on information related to the power: stops the supply of the fuel gas introduced through the fuel gas supply path, and only supplies the oxidizing gas introduced through the fuel electrode oxidizing gas supply path to the fuel electrode.

3. The solid oxide fuel cell generator according to claim 1 or 2, characterized in that: The solid oxide fuel cell generator further comprises: a branch valve connected to the fuel electrode oxidizing gas supply path and the fuel gas supply path, capable of switching between a state in which both the oxidizing gas and the fuel gas are introduced into the fuel electrode and a state in which only the oxidizing gas is introduced into the fuel electrode; The control unit adjusts the ratio by controlling the branch valve.

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