Fuel cell system

Abstract

A fuel cell system 100 comprises: a tank 110 for storing ammonia; a reformer 120 for thermally decomposing the ammonia supplied from the tank 110 to generate hydrogen; a polymer electrolyte fuel cell 130 for generating power using, as fuel, the hydrogen generated by the reformer 120; a turbine 142 rotated by a first exhaust gas generated in the polymer electrolyte fuel cell 130; a compressor 144 connected to the turbine 142 and compressing an oxygen-containing gas to supply the compressed oxygen-containing gas to the polymer electrolyte fuel cell 130; and a supply device 160 for joining a second exhaust gas discharged from the reformer 120 with the first exhaust gas.

Description

fuel cell system

[0001] This application claims the benefit of priority from Japanese Patent Application No. 2024-14762, filed February 2, 2024, the contents of which are incorporated herein by reference.

[0002] Ammonia has a higher energy density than hydrogen, and for this reason, the use of ammonia as a fuel for fuel cell systems is being considered (for example, see Patent Document 1).

[0003] Solid polymer fuel cells, which have a high ability to follow load fluctuations, are being considered for use in fuel cell systems that use ammonia. However, solid polymer fuel cells cannot have a mechanism for thermally decomposing ammonia internally due to temperature restrictions imposed by the polymer. Therefore, power cannot be generated by directly supplying ammonia to a solid polymer fuel cell. Therefore, fuel cell systems equipped with solid polymer fuel cells are being considered for incorporating a reformer that thermally decomposes ammonia to produce hydrogen.

[0004] Japanese Patent Application Laid-Open No. 2020-98699

[0005] However, polymer electrolyte fuel cells require the supply of oxygen-containing gases such as air. For this reason, fuel cell systems equipped with polymer electrolyte fuel cells are provided with electric compressors. In this case, the power generation efficiency of the fuel cell system is reduced by the amount of power consumed by the electric compressor.

[0006] Therefore, there is a demand for the development of technology that can reduce power consumption in fuel cell systems.

[0007] In view of the above problems, the present disclosure has an object to provide a fuel cell system that can reduce power consumption.

[0008] In order to solve the above problems, a fuel cell system according to one embodiment of the present disclosure includes a tank for storing ammonia, a reformer for generating hydrogen by thermally decomposing the ammonia supplied from the tank, a polymer electrolyte fuel cell for generating electricity using the hydrogen generated by the reformer as fuel, a turbine rotated by a first exhaust gas generated in the polymer electrolyte fuel cell, a compressor connected to the turbine for compressing an oxygen-containing gas and supplying it to the polymer electrolyte fuel cell, and a supply device for merging the second exhaust gas discharged from the reformer with the first exhaust gas or for exchanging heat with the first exhaust gas.

[0009] The fuel cell system may also include a combustor that burns the hydrogen produced by the reformer, and a third exhaust gas supply passage that supplies a third exhaust gas produced in the combustor to the reformer.

[0010] The fuel cell system may also include a heat exchanger that exchanges heat between the hydrogen produced by the reformer and the first exhaust gas produced in the polymer electrolyte fuel cell.

[0011] In addition, a portion of the oxygen-containing gas sent to the solid polymer fuel cell may be branched off and sent to the combustor, the turbine may include a first exhaust inlet and a second exhaust inlet, the second exhaust gas exhausted from the reformer may be sent to the first exhaust inlet, and the first exhaust gas generated in the solid polymer fuel cell may be sent to the second exhaust inlet.

[0012] The fuel cell system may also include a combustor turbine that is rotated by the second exhaust gas discharged from the reformer, and a combustor compressor that is connected to the combustor turbine and compresses the oxygen-containing gas and supplies it to the combustor.

[0013] According to the present disclosure, it is possible to reduce power consumption.

[0014] FIG. 1 is a diagram illustrating an example of a fuel cell system according to a first embodiment. FIG. 2 is a diagram illustrating an example of a fuel cell system according to a second embodiment. FIG. 3 is a diagram illustrating an example of a fuel cell system according to a third embodiment. FIG. 4 is a diagram illustrating an example of a fuel cell system according to a fourth embodiment. FIG. 5 is a diagram illustrating an example of a fuel cell system according to a fifth embodiment. FIG. 6 is a diagram illustrating an example of a fuel cell system according to a sixth embodiment.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation. Elements not directly related to the present disclosure are not shown.

[0016] [First Embodiment: Fuel Cell System 100] FIG. 1 is a diagram illustrating an example of a fuel cell system 100 according to a first embodiment. As shown in FIG. 1, the fuel cell system 100 according to the first embodiment includes a tank 110, a reformer 120, a polymer electrolyte fuel cell (hereinafter sometimes referred to as "PEFC") 130, a turbocharger 140, a combustor 150, a third exhaust gas supply passage 152, and a supply device 160. In FIGS. 1 to 6, solid arrows indicate the flows of ammonia and hydrogen. Furthermore, dashed arrows indicate the flows of an oxygen-containing gas. One-dot chain arrows indicate the flows of a first exhaust gas, a second exhaust gas, and a third exhaust gas.

[0017] The tank 110 stores either or both of liquid ammonia and gaseous ammonia.

[0018] The reformer 120 is connected to the tank 110 via an ammonia flow path 112. The ammonia stored in the tank 110 is supplied to the reformer 120 through the ammonia flow path 112. The reformer 120 thermally decomposes the ammonia supplied from the tank 110 to generate hydrogen. The reformer 120 is, for example, a heat exchanger that exchanges heat between the ammonia and a third exhaust gas (described later). The reformer 120 transfers heat contained in the third exhaust gas to the ammonia, thereby thermally decomposing the ammonia. The reformer 120 has, for example, an ammonia passage and an exhaust gas passage. Ammonia is supplied to the ammonia passage from the tank 110. For example, the ammonia passage is filled with a catalyst that promotes the thermal decomposition of ammonia. The catalyst is, for example, either one or both of a ruthenium (Ru) catalyst and a nickel (Ni) catalyst. The third exhaust gas is supplied to the exhaust gas passage from a combustor 150 (described later).

[0019] The anode (fuel electrode) of the PEFC 130 is connected to the reformer 120 via a hydrogen flow path 122. Hydrogen generated by the reformer 120 is supplied to the anode of the PEFC 130 through the hydrogen flow path 122. Furthermore, an oxygen-containing gas is supplied to the cathode (air electrode) of the PEFC 130 from a turbocharger 140, which will be described later. The oxygen-containing gas is, for example, air or oxygen-enriched air. The PEFC 130 generates power using the hydrogen generated by the reformer 120 as fuel. The power generated by the PEFC 130 is output to a load after its voltage is converted, for example, by a DC / DC converter.

[0020] The supercharger 140 has a turbine 142 and a compressor 144. Note that in the present embodiment, the supercharger 140 is, for example, an electric supercharger that has, in addition to the turbine 142 and the compressor 144, a motor 146 that rotates the compressor 144.

[0021] The turbine 142 is connected to an exhaust port of the PEFC 130 via a first exhaust gas passage 132. A first exhaust gas (e.g., cathode off-gas) exhausted from the exhaust port of the PEFC 130 is supplied to the turbine 142 through the first exhaust gas passage 132. The turbine 142 is rotated by the first exhaust gas generated in the PEFC 130.

[0022] The compressor 144 is connected to the turbine 142. The compressor 144 is rotated by the rotation of the turbine 142. In this embodiment, the compressor 144 is rotated by the motor 146 in addition to the rotation of the turbine 142. The compressor 144 compresses the oxygen-containing gas. In this embodiment, the compressor 144 is connected to the cathode of the PEFC 130 via the oxygen-containing gas flow path 134. Therefore, the oxygen-containing gas compressed by the compressor 144 is supplied to the cathode of the PEFC 130 through the oxygen-containing gas flow path 134.

[0023] The combustor 150 is connected to the reformer 120 via a hydrogen flow path 122 and a hydrogen flow path 124. The hydrogen flow path 124 branches off from the hydrogen flow path 122 and is connected to the combustor 150. A portion of the hydrogen generated by the reformer 120 is supplied to the combustor 150 via the hydrogen flow path 122 and the hydrogen flow path 124. The combustor 150 is also connected to the compressor 144 via an oxygen-containing gas flow path 134 and an oxygen-containing gas flow path 136. The oxygen-containing gas flow path 136 branches off from the oxygen-containing gas flow path 134 and is connected to the combustor 150. A portion of the oxygen-containing gas sent to the PEFC 130 by the compressor 144 is sent to the combustor 150 via the oxygen-containing gas flow path 134 and the oxygen-containing gas flow path 136. The flow rate of the oxygen-containing gas required in the combustor 150 is different from the flow rate of the oxygen-containing gas required in the PEFC 130 and is not uniquely determined. For this reason, the oxygen-containing gas flow path 136 according to this embodiment is provided with a flow rate adjustment valve 136a.

[0024] The combustor 150 combusts the hydrogen produced by the reformer 120 with the oxygen-containing gas supplied from the compressor 144 .

[0025] The third exhaust gas supply passage 152 connects the exhaust port of the combustor 150 and the inlet of the exhaust gas passage of the reformer 120. Therefore, the third exhaust gas generated in the combustor 150 is supplied to the reformer 120 through the third exhaust gas supply passage 152.

[0026] The supply device 160 merges the second exhaust gas discharged from the reformer 120 with the first exhaust gas generated in the PEFC 130. In this embodiment, the supply device 160 includes, for example, a second exhaust gas passage 162. The second exhaust gas passage 162 connects an outlet of the exhaust gas passage of the reformer 120 and the first exhaust gas passage 132.

[0027] As described above, the fuel cell system 100 according to the first embodiment includes a tank 110 for storing ammonia, a reformer 120 for generating hydrogen by thermally decomposing the ammonia supplied from the tank 110, a polymer electrolyte fuel cell 130 for generating electricity using the hydrogen generated by the reformer 120 as fuel, a turbine 142 that is rotated by a first exhaust gas generated in the polymer electrolyte fuel cell 130, a compressor 144 that is connected to the turbine 142 and compresses an oxygen-containing gas and supplies it to the polymer electrolyte fuel cell 130, and a supply device 160 that combines the second exhaust gas discharged from the reformer 120 with the first exhaust gas.

[0028] As a result, the fuel cell system 100 according to the first embodiment can rotate the turbine 142 using the first exhaust gas generated in the polymer electrolyte fuel cell 130. Therefore, the fuel cell system 100 according to the first embodiment can obtain the power required for the compressor 144 from the rotation of the turbine 142, thereby reducing the power consumption of the motor 146. Furthermore, the fuel cell system 100 according to the first embodiment supplies the high-temperature second exhaust gas exhausted from the reformer 120 to the turbine 142, in addition to the first exhaust gas. As a result, the fuel cell system 100 according to the first embodiment can rotate the turbine 142 using the first exhaust gas and the second exhaust gas. Therefore, the fuel cell system 100 according to the first embodiment can further increase the power supplied from the turbine 142 to the compressor 144. Therefore, the fuel cell system 100 according to the first embodiment can further reduce the power consumption of the motor 146.

[0029] Second Embodiment: Fuel Cell System 200 In the fuel cell system 100 according to the first embodiment, the second exhaust gas discharged from the reformer 120 is directly supplied to the turbine 142. However, the thermal energy of the second exhaust gas discharged from the reformer 120 may be supplied to the turbine 142. FIG. 2 is a diagram illustrating an example of a fuel cell system 200 according to a second embodiment. As shown in FIG. 2, the fuel cell system 200 according to the second embodiment includes a tank 110, a reformer 120, a polymer electrolyte fuel cell 130, a turbocharger 140, a combustor 150, a third exhaust gas supply passage 152, and a supply device 210. Note that components that are substantially the same as those in the fuel cell system 100 are denoted by the same reference numerals and will not be described again. The fuel cell system 200 according to this embodiment is the same as the fuel cell system 100 except that it includes a supply device 210 instead of the supply device 160.

[0030] The supply device 210 exchanges heat between the second exhaust gas discharged from the reformer 120 and the first exhaust gas generated in the PEFC 130. In this embodiment, the supply device 210 includes a second exhaust gas passage 212 and a first heat exchanger 214.

[0031] The base end of the second exhaust gas passage 212 is connected to the outlet of the exhaust gas passage of the reformer 120. The tip of the second exhaust gas passage 212 is open to the atmosphere.

[0032] The first heat exchanger 214 exchanges heat between the second exhaust gas discharged from the reformer 120 and the first exhaust gas before being supplied to the turbine 142. In this embodiment, the first heat exchanger 214 exchanges heat between the second exhaust gas flowing through the second exhaust gas passage 212 and the first exhaust gas flowing through the first exhaust gas passage 132. This allows the heat of the second exhaust gas to be transferred to the first exhaust gas, heating the first exhaust gas and cooling the second exhaust gas.

[0033] Therefore, in this embodiment, the turbine 142 is rotated by the first exhaust gas after heat exchange by the first heat exchanger 214 .

[0034] As described above, the fuel cell system 200 according to the second embodiment includes a tank 110 for storing ammonia, a reformer 120 for generating hydrogen by thermally decomposing the ammonia supplied from the tank 110, a polymer electrolyte fuel cell 130 for generating electricity using the hydrogen generated by the reformer 120 as fuel, a turbine 142 that is rotated by a first exhaust gas generated in the polymer electrolyte fuel cell 130, a compressor 144 connected to the turbine 142 for compressing an oxygen-containing gas and supplying it to the polymer electrolyte fuel cell 130, and a supply device 210 for exchanging heat between the second exhaust gas discharged from the reformer 120 and the first exhaust gas.

[0035] As a result, the fuel cell system 200 according to the second embodiment can heat the first exhaust gas with the high-temperature second exhaust gas, and then supply the heated first exhaust gas to the turbine 142. Therefore, the fuel cell system 200 according to the second embodiment can rotate the turbine 142 using the thermal energy of the second exhaust gas in addition to the energy of the first exhaust gas. Therefore, the fuel cell system 200 according to the second embodiment can further increase the power supplied from the turbine 142 to the compressor 144. As a result, the fuel cell system 200 according to the second embodiment can further reduce the power consumption of the motor 146.

[0036] Furthermore, compared to the fuel cell system 100 according to the first embodiment, the fuel cell system 200 according to the second embodiment can avoid a situation in which the second exhaust gas is directly supplied to the turbine 142. As a result, the fuel cell system 200 according to the second embodiment can avoid a situation in which a malfunction occurs in the turbine 142 due to dust or the like contained in the second exhaust gas.

[0037] Third Embodiment: Fuel Cell System 300 In the fuel cell system 100 according to the first embodiment, the energy contained in the second exhaust gas discharged from the reformer 120 is supplied to the turbine 142. However, other energy may be supplied to the turbine 142 in addition to the energy contained in the second exhaust gas discharged from the reformer 120. FIG. 3 is a diagram illustrating an example of a fuel cell system 300 according to a third embodiment. As shown in FIG. 3, the fuel cell system 300 according to the third embodiment includes a tank 110, a reformer 120, a polymer electrolyte fuel cell 130, a turbocharger 140, a combustor 150, a third exhaust gas supply passage 152, a supply device 160, and a second heat exchanger 310. Note that components that are substantially the same as those in the fuel cell system 100 are denoted by the same reference numerals, and description thereof will be omitted. The fuel cell system 300 according to this embodiment differs from the fuel cell system 100 in that a second heat exchanger 310 is added, but is otherwise the same.

[0038] The second heat exchanger 310 (heat exchanger) exchanges heat between the hydrogen generated by the reformer 120 and the first exhaust gas generated in the PEFC 130. In this embodiment, the second heat exchanger 310 exchanges heat between the hydrogen flow path 122, which flows between the PEFC 130 and a connection point with the hydrogen flow path 124, and the first exhaust gas flow path 132, which flows between the PEFC 130 and a connection point with the second exhaust gas flow path 162. This allows the heat of the hydrogen generated by the reformer 120 to be transferred to the first exhaust gas, heating the first exhaust gas and cooling the hydrogen.

[0039] Therefore, in this embodiment, the turbine 142 is rotated by the first exhaust gas and the second exhaust gas after heat exchange by the second heat exchanger 310 .

[0040] As described above, the fuel cell system 300 according to the third embodiment includes the second heat exchanger 310 in addition to the components of the fuel cell system 100 .

[0041] As a result, the fuel cell system 300 according to the third embodiment can heat the first exhaust gas with the high-temperature hydrogen produced in the reformer 120, and then supply the heated first exhaust gas to the turbine 142. Therefore, the fuel cell system 300 according to the third embodiment can rotate the turbine 142 using the thermal energy of the hydrogen in addition to the energy of the first exhaust gas and the second exhaust gas. Therefore, the fuel cell system 300 according to the third embodiment can further increase the power supplied from the turbine 142 to the compressor 144. As a result, the fuel cell system 300 according to the third embodiment can further reduce the power consumption of the motor 146.

[0042] Furthermore, the fuel cell system 300 according to the third embodiment can use the second heat exchanger 310 to lower the temperature of the hydrogen before it is supplied to the PEFC 130. This makes it possible to prevent the PEFC 130 from being deteriorated by heat.

[0043] [Fourth Embodiment: Fuel Cell System 400] In the fuel cell system 200 according to the second embodiment, the thermal energy of the second exhaust gas discharged from the reformer 120 is supplied to the turbine 142. However, in addition to the thermal energy of the second exhaust gas discharged from the reformer 120, other thermal energy may be supplied to the turbine 142. FIG. 4 is a diagram illustrating an example of a fuel cell system 400 according to a fourth embodiment. As shown in FIG. 4, the fuel cell system 400 according to the fourth embodiment includes a tank 110, a reformer 120, a polymer electrolyte fuel cell 130, a turbocharger 140, a combustor 150, a third exhaust gas supply passage 152, a supply device 410, and a second heat exchanger 310. Note that components that are substantially the same as those in the fuel cell systems 100, 200, and 300 are denoted by the same reference numerals, and description thereof will be omitted. The fuel cell system 400 according to this embodiment differs from the fuel cell system 200 in that a second heat exchanger 310 is added, but is otherwise the same.

[0044] The supply device 410 exchanges heat between the second exhaust gas discharged from the reformer 120 and the first exhaust gas generated in the PEFC 130. In this embodiment, the supply device 410 includes a second exhaust gas passage 212 and a first heat exchanger 414.

[0045] The first heat exchanger 414 exchanges heat between the second exhaust gas discharged from the reformer 120 and the first exhaust gas that has been heat exchanged by the second heat exchanger 310 and has not yet been supplied to the turbine 142. In the present embodiment, the first heat exchanger 414 exchanges heat between the second exhaust gas flowing through the second exhaust gas passage 212 and the first exhaust gas that flows between the turbine 142 and a location in the first exhaust gas passage 132 where the second heat exchanger 310 is provided. This allows the heat of the second exhaust gas discharged from the reformer 120 to be transferred to the first exhaust gas that has undergone heat exchange, further heating the first exhaust gas and cooling the second exhaust gas.

[0046] Therefore, in this embodiment, the turbine 142 is rotated by the first exhaust gas after heat exchange by the second heat exchanger 310 and the first heat exchanger 414 .

[0047] As described above, the fuel cell system 400 according to the fourth embodiment includes the second heat exchanger 310 and the supply device 410 .

[0048] As a result, the fuel cell system 400 according to the fourth embodiment can heat the first exhaust gas with high-temperature hydrogen and high-temperature second exhaust gas, and then supply the heated first exhaust gas to the turbine 142. Therefore, the fuel cell system 400 according to the fourth embodiment can rotate the turbine 142 using the thermal energy of the hydrogen and the thermal energy of the second exhaust gas in addition to the energy of the first exhaust gas. Therefore, the fuel cell system 400 according to the fourth embodiment can further increase the power supplied from the turbine 142 to the compressor 144. As a result, the fuel cell system 400 according to the fourth embodiment can further reduce the power consumption of the motor 146.

[0049] Fifth Embodiment: Fuel Cell System 500 In the fuel cell system 100 according to the first embodiment, a flow rate control valve 136a is provided in the oxygen-containing gas flow path 136 to throttle the flow rate of the oxygen-containing gas supplied from the compressor 144 to the combustor 150. However, pressure loss occurs in the flow rate control valve 136a, causing a drop in the pressure of the oxygen-containing gas supplied to the combustor 150. This causes a drop in the pressure of the third exhaust gas generated in the combustor 150 and the second exhaust gas discharged from the reformer 120. This reduces the pressure of the second exhaust gas supplied to the turbine 142 by the supply device 160, and reduces the energy imparted to the turbine 142 by the second exhaust gas. Therefore, a fuel cell system 500 according to the fifth embodiment does not use the flow rate control valve 136a, preventing a drop in the pressure of the oxygen-containing gas supplied to the combustor 150.

[0050] Fig. 5 is a diagram illustrating an example of a fuel cell system 500 according to a fifth embodiment. As shown in Fig. 5, the fuel cell system 500 according to the fifth embodiment includes a tank 110, a reformer 120, a polymer electrolyte fuel cell 130, a turbocharger 540, a combustor 150, a third exhaust gas supply passage 152, and a supply device 160. Note that components that are substantially the same as those in the fuel cell system 100 described above are denoted by the same reference numerals, and description thereof will be omitted. The fuel cell system 500 according to this embodiment is the same as the fuel cell system 100 except that a turbine 542 is added instead of the flow rate control valve 136a.

[0051] In the fuel cell system 500 according to the fifth embodiment, the oxygen-containing gas flow path 136 is not provided with a flow rate adjustment valve 136a.

[0052] The supercharger 540 has a turbine 542 and a compressor 144. Note that in the present embodiment, the supercharger 540 is, for example, an electric supercharger that has, in addition to the turbine 542 and the compressor 144, a motor 146 that rotates the compressor 144.

[0053] The turbine 542 is, for example, a turbine having two scroll passages (for example, a twin scroll turbine or a double scroll turbine). The scroll passage is a passage that connects an accommodation space in the turbine that accommodates a turbine impeller with an exhaust intake port through which exhaust gas is taken in from the outside, and is a passage that guides the exhaust gas taken in from the outside to the accommodation space. The turbine 542 includes a first exhaust intake port 542 a and a second exhaust intake port 542 b.

[0054] In this embodiment, the second exhaust gas passage 162 of the supply device 160 is connected to the first exhaust inlet 542a. Therefore, due to the rotation of the turbine 142, the second exhaust gas is drawn from the reformer 120 to the first exhaust inlet 542a, and as a result, the third exhaust gas is sent from the combustor 150 to the reformer 120 through the third exhaust gas supply passage 152. In addition, the oxygen-containing gas compressed by the compressor 144 is sent to the combustor 150 through the oxygen-containing gas passage 134 and the oxygen-containing gas passage 136.

[0055] In this embodiment, the first exhaust gas passage 132 is connected to the second exhaust inlet port 542b, so that the first exhaust gas generated in the PEFC 130 by the rotation of the turbine 142 is sent to the second exhaust inlet port 542b.

[0056] As described above, the fuel cell system 500 according to the fifth embodiment does not have a flow control valve 136a, but has a turbine 542 including a first exhaust intake port 542a and a second exhaust intake port 542b, and the second exhaust gas exhausted from the reformer 120 is sent to the first exhaust intake port 542a, and the first exhaust gas generated in the polymer electrolyte fuel cell 130 is sent to the second exhaust intake port 542b.

[0057] In the fuel cell system 500 according to the fifth embodiment, the flow rate control valve 136a can be eliminated by optimizing the difference in characteristics of the scroll passages connected to the first exhaust inlet 542a and the second exhaust inlet 542b in the turbine 542, depending on the ratio between the flow rate of the oxygen-containing gas sent to the combustor 150 and the flow rate of the oxygen-containing gas sent to the PEFC 130. The pressure loss in the scroll passage connected to the first exhaust inlet 542a is much smaller than the pressure loss in the flow rate control valve 136a. Therefore, the fuel cell system 500 according to the fifth embodiment can prevent pressure loss due to the flow rate control valve 136a and can prevent a pressure drop in the oxygen-containing gas supplied to the combustor 150. Therefore, the fuel cell system 500 according to the fifth embodiment can also prevent a pressure drop in the third exhaust gas generated in the combustor 150 and the second exhaust gas exhausted from the reformer 120. Therefore, the fuel cell system 500 according to the fifth embodiment can prevent a drop in the pressure of the second exhaust gas supplied to the turbine 542 by the supply device 160, thereby making it possible to avoid a situation in which the energy imparted to the turbine 542 by the second exhaust gas is reduced.

[0058] [Sixth Embodiment: Fuel Cell System 600] Figure 6 is a diagram illustrating an example of a fuel cell system 600 according to a sixth embodiment. As shown in Figure 6, the fuel cell system 600 according to the sixth embodiment includes a tank 110, a reformer 120, a polymer electrolyte fuel cell 130, a turbocharger 140, a combustor 150, a third exhaust gas supply passage 152, a combustor turbocharger 640, a supply device 160, and a second exhaust gas passage 670. Note that components that are substantially the same as those in the fuel cell system 100 described above are denoted by the same reference numerals, and descriptions thereof will be omitted. The fuel cell system 600 according to this embodiment is the same as the fuel cell system 100 except that a combustor turbocharger 640 is added instead of the flow rate adjustment valve 136a.

[0059] The combustor supercharger 640 includes a combustor turbine 642 and a combustor compressor 644. The combustor supercharger 640 does not necessarily include a motor.

[0060] A second exhaust gas passage 670 branched from the second exhaust gas passage 162 of the supply device 160 is connected to the combustor turbine 642. A portion of the second exhaust gas exhausted from the reformer 120 is supplied to the combustor turbine 642 through the second exhaust gas passage 162 and the second exhaust gas passage 670. The combustor turbine 642 is rotated by the second exhaust gas exhausted from the reformer 120. A flow rate adjustment valve 670a is provided in the second exhaust gas passage 670. The flow rate adjustment valve 670a determines the distribution ratio between the second exhaust gas supplied from the reformer 120 to the turbine 142 and the second exhaust gas supplied from the reformer 120 to the combustor turbine 642.

[0061] The combustor compressor 644 is connected to the combustor turbine 642. The combustor compressor 644 is rotated by the rotation of the combustor turbine 642. An oxygen-containing gas supply passage 646 is connected to the combustor compressor 644. The oxygen-containing gas supply passage 646 connects the combustor compressor 644 to an oxygen-containing gas supply source.

[0062] In this embodiment, the oxygen-containing gas flow path 136 connects the oxygen-containing gas flow path 134 and the oxygen-containing gas supply flow path 646. The oxygen-containing gas flow path 136 is provided with an on-off valve 136b.

[0063] The combustor compressor 644 compresses the oxygen-containing gas. In the present embodiment, the combustor compressor 644 is connected to the combustor 150 via an oxygen-containing gas flow path 648. Therefore, the oxygen-containing gas compressed by the combustor compressor 644 is supplied to the combustor 150 through the oxygen-containing gas flow path 648.

[0064] At the start-up of the fuel cell system 600, the on-off valve 136b is opened, and the oxygen-containing gas compressed by the compressor 144 of the turbocharger 140 is supplied to the combustor compressor 644. When the rotation speed of the combustor compressor 644 reaches the rotation speed for rated operation, the on-off valve 136b is closed. As a result, during rated operation, the combustor compressor 644 compresses the oxygen-containing gas supplied through the oxygen-containing gas supply passage 646.

[0065] As described above, the fuel cell system 600 according to the sixth embodiment includes a combustor turbine 642 and a combustor compressor 644 in addition to the components of the fuel cell system 100 .

[0066] As a result, the fuel cell system 600 according to the sixth embodiment can rotate the combustor turbine 642 of the combustor turbocharger 640 using the second exhaust gas. Therefore, the fuel cell system 600 according to the sixth embodiment can supply power from the combustor turbine 642 to the combustor compressor 644 without consuming electric power. Therefore, the fuel cell system 600 according to the sixth embodiment can reduce the power consumption of the turbocharger 140.

[0067] Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to the above-described embodiments. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0068] For example, in the first to sixth embodiments, the fuel cell systems 100, 200, 300, 400, 500, and 600 are illustrated as including the combustor 150. By including the combustor 150, ammonia can be efficiently thermally decomposed in the reformer 120. However, the fuel cell systems 100, 200, 300, 400, 500, and 600 may include a device capable of supplying a high-temperature fluid to the reformer 120 instead of the combustor 150. The device capable of supplying a high-temperature fluid may be, for example, a solid oxide fuel cell. In this case, exhaust gas (either one or both of cathode off-gas and anode off-gas) discharged by the solid oxide fuel cell may be supplied to the reformer 120.

[0069] In the fuel cell system 400 according to the fourth embodiment, the first heat exchanger 414 is provided between the second heat exchanger 310 and the turbine 142 in the first exhaust gas passage 132. However, the first heat exchanger 414 may be provided between the PEFC 130 and the second heat exchanger 310 in the first exhaust gas passage 132.

[0070] Furthermore, the fuel cell systems 200, 300, 400 according to the second to fourth embodiments may omit the flow rate adjustment valve 136a and include a turbocharger 540 instead of the turbocharger 140. Similarly, the fuel cell systems 200, 300, 400 according to the second to fourth embodiments may omit the flow rate adjustment valve 136a and include a combustor turbocharger 640 in addition to the turbocharger 140.

[0071] 100: Fuel cell system 110: Tank 120: Reformer 130: Polymer electrolyte fuel cell (PEFC) 142: Turbine 144: Compressor 150: Combustor 152: Third exhaust gas supply passage 160: Supply device 200: Fuel cell system 210: Supply device 214: First heat exchanger 300: Fuel cell system 310: Second heat exchanger (heat exchanger) 400: Fuel cell system 410: Supply device 414: First heat exchanger 500: Fuel cell system 542: Turbine 542a: First exhaust intake port 542b: Second exhaust intake port 600: Fuel cell system 642: Combustor turbine 644: Combustor compressor

Claims

1. A fuel cell system comprising: a tank for storing ammonia; a reformer that thermally decomposes the ammonia supplied from the tank to produce hydrogen; a polymer electrolyte fuel cell that generates electricity using the hydrogen produced by the reformer as fuel; a turbine that is rotated by a first exhaust gas produced in the polymer electrolyte fuel cell; a compressor connected to the turbine that compresses an oxygen-containing gas and supplies it to the polymer electrolyte fuel cell; and a supply device that merges a second exhaust gas discharged from the reformer with the first exhaust gas or exchanges heat with the first exhaust gas.

2. The fuel cell system according to claim 1, comprising: a combustor that combusts the hydrogen produced by the reformer; and a third exhaust gas supply passage that supplies a third exhaust gas produced in the combustor to the reformer.

3. The fuel cell system according to claim 1 or 2, further comprising a heat exchanger for exchanging heat between the hydrogen produced by the reformer and the first exhaust gas produced in the polymer electrolyte fuel cell.

4. A fuel cell system as described in claim 2, wherein a portion of the oxygen-containing gas sent to the polymer electrolyte fuel cell is branched off and sent to the combustor, the turbine includes a first exhaust inlet and a second exhaust inlet, the second exhaust gas exhausted from the reformer is sent to the first exhaust inlet, and the first exhaust gas generated in the polymer electrolyte fuel cell is sent to the second exhaust inlet.

5. The fuel cell system according to claim 2, comprising: a combustor turbine that is rotated by the second exhaust gas discharged from the reformer; and a combustor compressor that is connected to the combustor turbine and compresses an oxygen-containing gas and supplies the compressed gas to the combustor.

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