Fuel cell system

Abstract

To efficiently remove condensed water from a fuel-off gas refluxed to a fuel supply line in a system where the fuel off-gas is passed through a heat exchanger and refluxed to the fuel supply line.SOLUTION: A fuel cell system comprises a power generation module including a fuel cell stack, a fuel supply system, a circulation system, and a condensed water line. The fuel supply system includes a fuel supply line connected to the fuel inlet and fuel supply source of the power generation module connected to an anode inlet, and a fuel blower. The circulation system includes a fuel off-gas line connected to a fuel off-gas outlet of the power generation module connected to the anode outlet, a heat exchanger, and a reflux line connected to the downstream side of the heat exchanger in the fuel supply line and the fuel supply line. The condensed water line branches from the downstream side of the heat exchanger in the fuel off-gas line and discharges condensed water. The reflux line is connected to the fuel supply line at an upper position than the branch point between the fuel off-gas line and the condensed water line.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] This specification discloses a fuel cell system. [Background technology]

[0002] A conventional fuel cell system of this type includes a cell stack, a high-temperature housing that houses the cell stack and a combustor, a fuel gas supply passage that supplies fuel gas to the cell stack by operating a fuel gas pump, a fuel off-gas delivery passage that guides fuel off-gas from the cell stack out of the high-temperature housing and then back into the high-temperature housing to supply it to the combustor, a second heat exchanger disposed in an intermediate position (outside the high-temperature housing) of the fuel off-gas delivery passage, a recycle passage that branches off from the fuel off-gas delivery passage downstream of the second heat exchanger and is connected to the fuel gas supply passage between the fuel gas pump and a second throttle member, and a recycle valve disposed in the recycle passage (see, for example, Patent Document 1). In this fuel cell system, the fuel off-gas from the cell stack is cooled in the second heat exchanger and then delivered to the combustor, and a portion of the fuel off-gas delivered from the second heat exchanger to the combustor is returned to the fuel gas supply passage through the recycle passage by negative pressure generated by operating the fuel gas pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7221641 Summary of the Invention [Problem to be solved by the invention]

[0004] When fuel off-gas from a fuel cell stack is passed through a heat exchanger and returned to a fuel supply line, it is desirable to minimize the amount of water vapor contained in the returned fuel off-gas in order to improve the power generation efficiency of the fuel cell stack.

[0005] The present disclosure has a primary object to effectively remove water vapor from fuel off-gas that is returned to a fuel supply line by passing the fuel off-gas through a heat exchanger. [Means for solving the problem]

[0006] The present disclosure has adopted the following means to achieve the above-mentioned main object.

[0007] The fuel cell system of the present disclosure comprises: a power generation module including a fuel cell stack that generates power using a fuel gas, which is at least one of hydrogen gas and ammonia gas, supplied to an anode and an oxidant gas that is supplied to a cathode, and a heat-insulating module case that houses the fuel cell stack; a fuel supply system including a fuel supply line connected to a fuel inlet of the power generation module connected to the inlet of the anode and a fuel supply source, and a fuel blower provided in the fuel supply line; a circulation system including: a fuel off-gas line connected to a fuel off-gas outlet of the power generation module connected to an outlet of the anode; a heat exchanger provided in the fuel off-gas line; and a reflux line connected to the fuel supply line and a downstream side of the heat exchanger in the fuel supply line; a condensed water line that branches off from the fuel off-gas line at a downstream side of the heat exchanger and discharges condensed water obtained by condensing water vapor contained in the fuel off-gas in the heat exchanger; Equipped with the reflux line is connected to the fuel supply line at a position above a branch point between the fuel off-gas line and the condensed water line. The gist of this is as follows.

[0008] In the fuel cell system disclosed herein, the fuel off-gas passes through a heat exchanger and is returned to the fuel supply line via a return line. The condensed water line branches off from the fuel off-gas line downstream of the heat exchanger, and the return line is connected to the fuel supply line above the branch point of the fuel off-gas line and the condensed water line. This allows water vapor to be efficiently removed from the fuel off-gas returned to the fuel supply line. As a result, the power generation efficiency of the fuel cell stack can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view of the appearance of a fuel cell system including a plurality of fuel cell units. [Figure 2] FIG. 2 is a perspective view of the inside of the fuel cell unit. [Figure 3] FIG. 2 is an internal perspective view of the fuel cell unit excluding the frame. [Figure 4] FIG. 2 is a front view of the inside of the fuel cell unit. [Figure 5] FIG. 2 is an internal front view of the fuel cell unit excluding the frame. [Figure 6] FIG. 2 is an internal side view of the fuel cell unit. [Figure 7] FIG. 2 is an internal side view of the fuel cell unit excluding the frame. [Figure 8] FIG. 2 is a partial enlarged view of the fuel cell unit. [Figure 9] FIG. 1 is a schematic diagram of a fuel cell system. [Figure 10] FIG. 2 is an external perspective view of a fuel blower subassembly. [Figure 11] FIG. 2 is an external perspective view of an air blower subassembly. [Figure 12] FIG. 2 is an external perspective view of a condensate tank subassembly. [Figure 13] FIG. 10 is a diagram illustrating a configuration of a portion of a fuel cell system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will be described with reference to the drawings.

[0011] FIG. 1 is an external perspective view of a fuel cell system 10 including a plurality of fuel cell units 20. FIG. 2 is an internal perspective view of the fuel cell unit 20, and FIG. 3 is an internal perspective view of the fuel cell unit 20 excluding the frame 21. FIG. 4 is an internal front view of the fuel cell unit 20, and FIG. 5 is an internal front view of the fuel cell unit 20 excluding the frame 21. FIG. 6 is an internal side view of the fuel cell unit 20, and FIG. 7 is an internal side view of the fuel cell unit 20 excluding the frame 21. FIG. 8 is a partially enlarged view of the fuel cell unit 20, and FIG. 9 is a schematic configuration diagram of the fuel cell system 10. FIG. 10 is an external perspective view of the fuel blower subassembly 42, FIG. 11 is an external perspective view of the air blower subassembly 52, and FIG. 12 is an external perspective view of the condensed water tank subassembly 65.

[0012] 1, the fuel cell system 10 of this embodiment includes a plurality of (N, for example, four) fuel cell units 20, each including a plurality of (M, for example, four) power generation modules 30, and a housing 11 that covers the plurality of fuel cell units 20. The plurality of fuel cell units 20 are installed side by side, and the power generation modules 30 are connected in series between the plurality of fuel cell units 20, thereby configuring the fuel cell system 10.

[0013] Each fuel cell unit 20 is a unit that has a roughly rectangular parallelepiped appearance, and as shown in Figures 2, 4, and 6, is provided with a frame 21 that supports and fixes various components of the fuel cell unit 20. The frame 21 is made up of multiple pillars installed around the periphery and connected by beams.

[0014] 9, each fuel cell unit 20 includes a power generation module 30 including one fuel cell stack 31, a fuel supply system 40, an oxidant supply system 50, a circulation system 60, an exhaust heat recovery system 70, and an electronic control unit (ECU) 80 (see FIG. 1). In this embodiment, each fuel cell unit 20 includes a plurality of power generation modules 30 (fuel cell stacks 31) connected in series. Each power generation module 30 is provided with one fuel supply system 40, one oxidant supply system 50, one circulation system 60, and one electronic control unit 80.

[0015] The multiple power generation modules 30 of the fuel cell unit 20 are fixed to the frame 21 with bolts so as to be aligned vertically. As shown in FIG. 9, each power generation module 30 includes a fuel cell stack 31 as well as a combustor 32, a heat exchanger, etc. These are housed in a thermally insulating module case 35. The fuel cell stack 31 includes multiple solid oxide unit cells, each of which includes an electrolyte, an anode (fuel electrode) disposed on one side of the electrolyte, and a cathode (air electrode) disposed on the other side of the electrolyte. The fuel cell stack 31 generates electricity through an electrochemical reaction between hydrogen contained in fuel gas supplied from a fuel supply source 1 (e.g., a hydrogen tank) and oxygen contained in oxidant gas (air).

[0016] As shown in FIGS. 2, 3, and 9, each of the fuel supply systems 40 of the fuel cell unit 20 includes a fuel gas pipe 41 and a fuel blower subassembly 42 including a fuel blower 43 installed in the fuel gas pipe 41. The fuel blower subassemblies 42 of the fuel supply systems 40 are arranged vertically and are installed facing the corresponding power generation module 30 in the front-to-rear direction (lateral direction). The fuel gas pipe 41 branches off from a common fuel pipe 25 connected to the fuel supply source 1 and is connected to a fuel gas inlet GI of the corresponding power generation module 30 (module case 35). An on-off valve 26 (dual valve) is installed in the fuel pipe 25. By operating the fuel blower 43, the fuel gas (hydrogen gas) from the fuel supply source 1 is distributed from the fuel pipe 25 to each fuel gas pipe 41 and introduced into the corresponding power generation module 30 from the fuel gas inlet GI. The fuel gas introduced into the power generation module 30 is then supplied to the anode of the fuel cell stack 31 through a fuel gas flow path within the power generation module 30. The fuel supply system 40 (fuel blower subassembly 42) is installed facing the corresponding power generation module 30, and the fuel gas inlet GI is formed on the side (front) of the power generation module 30 facing the fuel supply system 40. This makes it possible to shorten the piping length of the fuel supply system 40 (fuel gas piping 41) and to simplify piping management. In addition, because a fuel blower 43 is installed in each fuel gas piping 41 (branch pipe), the amount of fuel gas supplied to each power generation module 30 can be controlled by individually controlling each fuel blower 43.

[0017] 10, in addition to the fuel blower 43, the fuel blower subassembly 42 includes a governor 44 (zero governor) and a flow rate sensor 45. The flow rate sensor 45, governor 44, and fuel blower 43 are installed in this order from the upstream side of the fuel gas pipe 41. The flow rate sensor 45, governor 44, and fuel blower 43 are attached to a bracket 46, and the bracket 46 is fixed to a beam of the frame 21 with bolts. Making the fuel blower subassembly 42 detachable from the frame 21 further improves maintainability.

[0018] As shown in FIGS. 2, 3, 6, 7, and 9, the multiple oxidant supply systems 50 of the fuel cell unit 20 include air pipes 51 and air blower subassemblies 52 including air blowers 53 installed in the air pipes 51. The air blower subassemblies 52 of the multiple oxidant supply systems 50 are installed together in a space defined at the bottom of the frame 21 below the multiple power generation modules 30 arranged vertically. This allows the air blower subassemblies 52 to be installed efficiently in a limited space, thereby further miniaturizing the fuel cell system 10. In this embodiment, the air blower subassemblies 52 are installed so that multiple (two) air blower subassemblies 52 are arranged vertically in multiple tiers (two tiers) arranged in the front-to-rear (lateral) direction. An air filter 54 is attached to one end of the air pipes 51, and the other end of the air pipes 51 is connected to the air inlets AI of the corresponding power generation modules 30. By operating the air blower 53, air is sucked into the air pipe 51 through the air filter 54. The sucked air then passes through the air pipe 51 and is introduced into the corresponding power generation module 30 from the air inlet AI. The air introduced into the power generation module 30 is then supplied to the cathode of the fuel cell stack 31 through the air flow path within the power generation module 30. Because an air blower 53 is installed in each air pipe 51, the amount of air supplied to each power generation module 30 can be controlled by individually controlling each air blower 53. In this embodiment, as shown in FIG. 8, the air inlet AI is formed on the same side (front) as the side (front surface) on which the fuel gas inlet GI of the power generation module 30 (module case 35) is formed. As shown in FIG. 7, each air pipe 51 extends upward from each air blower subassembly 52 installed at the bottom of the frame 21, passing between the power generation module 30 and the fuel supply system 40, and is connected to the air inlet AI of the corresponding power generation module 30. This allows the air pipe 51 to be connected from the air blower subassembly 52 to the power generation module 30 without interfering with the layout of the power generation module 30 or the fuel supply system 40 .

[0019] 11, the air blower subassembly 52 includes a flow rate sensor 55 in addition to an air blower 53 and an air filter 54. The air filter 54, air blower 53, and flow rate sensor 55 are installed in the air piping 51 in this order from the upstream side of the air piping 51. The air filter 54, air blower 53, and flow rate sensor 55 are attached to a bracket 56, and the bracket 56 is fixed to a beam of the frame 21 with bolts. Making the air blower subassembly 52 detachable from the frame 21 with bolts further improves maintainability.

[0020] As shown in Figures 3, 4, 5, 8 and 9, each of the multiple circulation systems 60 of the fuel cell unit 20 includes a fuel off-gas piping 61, a condenser 62 installed in the fuel off-gas piping 61, a return piping 63 branching off from the fuel off-gas piping 61 downstream of the condenser 62, a combustion gas piping 64 and a condensed water piping 68, and a condensed water tank subassembly 65 including a condensed water tank 66.

[0021] One end of the fuel offgas piping 61 is connected to the fuel offgas outlet FO of the power generation module 30. One end of the return piping 63 is connected to a branch point J1 on the other end side of the fuel offgas piping 61, and the other end of the return piping 63 is connected to a portion of the fuel gas piping 41 of the corresponding fuel supply system 40 between the fuel blower 43 and the governor 44. The return piping 63 is also formed with an orifice OF serving as a pressure regulating valve. One end of the combustion gas piping 64 is connected to the branch point J1 of the fuel offgas piping 61, and the other end of the combustion gas piping 64 is connected to a combustion gas inlet CI of the corresponding power generation module 30 (module case 35). In this embodiment, the fuel offgas outlet FO and the combustion gas inlet CI are formed on the same side (front surface) as the side surface on which the fuel gas inlet GI of the power generation module 30 (module case 35) is formed. This makes it possible to shorten the piping length of the piping of the circulation system 60 (the fuel offgas piping 61, the return piping 63, and the combustion gas piping 64) and to facilitate the routing of the piping. One end of the condensed water pipe 68 is connected to a branch point J2 in the fuel offgas pipe 61 downstream of the condenser 62 and upstream of the branch point J1, and the other end of the condensed water pipe 68 is connected to a condensed water tank 66.

[0022] The condenser 62 condenses water vapor contained in the fuel off-gas. As shown in FIG. 8 , the condenser 62 has a vertically extending rectangular cylindrical shape and is installed on the side facing the fuel supply system 40 of the corresponding power generation module 30. A fuel off-gas inlet 62a is formed in the upper part of the condenser 62, through which the fuel off-gas discharged from the fuel off-gas outlet FO is introduced. A fuel off-gas outlet 62b is formed in the lower part of the condenser 62, through which the fuel off-gas that has passed through the condenser 62 is discharged. The condenser 62 is installed so that the fuel off-gas inlet 62a is located below the fuel off-gas outlet FO of the corresponding power generation module 30 and the fuel off-gas outlet 62b is located above the branch point J2 from the fuel off-gas piping 61 to the condensed water piping 68. This allows the condensed water obtained by condensing the water vapor contained in the fuel off-gas in the condenser 62 to be smoothly discharged.

[0023] The fuel off-gas discharged from the fuel off-gas outlet FO via the fuel off-gas flow path in the power generation module 30 from the anode outlet of the fuel cell stack 31 passes through the fuel off-gas piping 61 and condenses in the condenser 62 through heat exchange with a heat exchange medium (cooling water), causing water vapor contained in the fuel off-gas to condense. The fuel off-gas that has passed through the condenser 62 is then distributed to the return piping 63 and the combustion gas piping 64. The fuel off-gas distributed to the return piping 63 is drawn into the fuel gas piping 41 by negative pressure generated by the operation of the fuel blower 43, and is introduced into the fuel gas inlet GI of the power generation module 30 together with the fuel gas from the fuel supply source 1 and supplied to the anode inlet of the fuel cell stack 31. Meanwhile, the fuel off-gas distributed to the combustion gas piping 64 is introduced into the combustion gas inlet CI of the power generation module 30 and supplied to the combustor 32. The fuel off-gas supplied to the combustor 32 is then combusted in the combustor 32 together with the oxidant off-gas supplied from the cathode outlet of the fuel cell stack 31. In this embodiment, an orifice OF is formed in the reflux piping 63, and the fuel off-gas that has passed through the condenser 62 is distributed to the reflux piping 63 and the combustion gas piping 64 at a distribution rate that corresponds to the diameter of the orifice OF. By designing the diameter of the orifice OF so that the fuel off-gas is distributed to the fuel gas piping 41 and the combustor 32 at an optimal distribution rate, the efficiency of the fuel cell system 10 can be improved with a simple configuration. Note that, although the orifice OF is provided in the reflux piping 63 in this embodiment, a solenoid valve may also be provided.

[0024] Furthermore, the condensed water obtained by condensing the water vapor contained in the fuel off-gas in the condenser 62 is supplied to a condensed water tank 66 through a condensed water pipe 68 branching off from the fuel off-gas pipe 61 at a branch point J2, and is stored in the condensed water tank 66. A drain valve 67 is attached to the outlet of the condensed water tank 66, and the condensed water stored in the condensed water tank 66 is discharged to the outside by opening the drain valve 67.

[0025] As shown in Fig. 8, in this embodiment, the branch point J1 is formed above the branch point J2. The fuel blower 43, the orifice OF, and the combustion gas inlet CI of the power generation module 30 are located above the branch point J1, and the condensed water tank 66 is located below the branch point J2. The fuel off-gas pipe 61 extends upward from the branch point J2 and branches into a return pipe 63 and a combustion gas pipe 64 at the branch point J1. The return pipe 63 is connected to the fuel gas pipe 41 above the branch point J1 via the orifice OF, and the combustion gas pipe 64 is connected to the combustion gas inlet CI located above the branch point J1. Meanwhile, the condensed water pipe 68 extends downward from the branch point J2 and is connected to the condensed water tank 66 installed at the bottom of the fuel cell unit 20. This allows liquid condensed water to easily flow from the fuel off-gas piping 61 to the condensed water piping 68, and also allows gaseous fuel off-gas to easily flow from the fuel off-gas piping 61 to the return piping 63 and the combustion gas piping 64. As a result, water vapor contained in the fuel off-gas can be effectively removed and the fuel off-gas can be returned to the fuel cell stack 31, further improving the power generation efficiency of the fuel cell stack 31.

[0026] As shown in FIGS. 2 to 7 , the condensed water tank subassemblies 65 (condensed water tanks 66 and drain valves 67) of the multiple circulation systems 60 are collectively installed in a space at the bottom of the frame 21 defined below the vertically arranged multiple fuel supply systems 40 (fuel blower subassemblies 42). In this embodiment, the condensed water tank subassemblies 65 are installed side by side (horizontally) below the vertically arranged multiple fuel supply systems 40 (fuel blower subassemblies 42). This allows the multiple condensed water tank subassemblies 65 to be compactly arranged in a limited space, thereby further miniaturizing the fuel cell unit 20. As shown in FIG. 12 , each condensed water tank subassembly 65 is attached to a bracket 69, which is fixed to the lowest beam of the frame 21 with bolts. The condensed water tank subassemblies 65 can be attached and detached to the frame 21 with bolts, thereby further improving maintainability.

[0027] As shown in FIGS. 2 to 7 and 9 , the exhaust heat recovery system 70 includes a plurality of flue gas pipes 72, each connected at one end to a flue gas outlet EX formed in the corresponding power generation module 30 (module case 35), and an exhaust gas heat exchanger 71 connected to the other ends of the plurality of flue gas pipes 72. The exhaust gas heat exchanger 71 is installed below the plurality of fuel supply systems 40 and above the plurality of condensate tank subassemblies 65. The flue gas generated by combustion of fuel off-gas in the combustor 32 of each power generation module 30 passes through a flue gas flow path in each power generation module 30, is discharged from the flue gas outlet EX to each flue gas pipe 72, and is introduced into the exhaust gas heat exchanger 71 via each flue gas pipe 72. The flue gas then exchanges heat with a heat exchange medium in the exhaust gas heat exchanger 71, and is then discharged to the outside air through an exhaust gas collection pipe. Although not shown, the exhaust gas collecting pipe extends in the arrangement direction of the multiple fuel cell units 20 that make up the fuel cell system 10, collects the combustion exhaust gas discharged from the exhaust gas heat exchanger 71 of each fuel cell unit 20, and discharges it to the outside air. The heat recovered through heat exchange with the heat exchange medium is supplied to heat utilization equipment installed in a factory or the like. In this embodiment, the combustion exhaust gas outlet EX is formed on the same side (front surface) as the side surface on which the fuel gas inlet GI and combustion gas inlet CI of the power generation module 30 (module case 35) are formed.

[0028] An electronic control unit 80 for each fuel cell unit 20 is provided for each power generation module 30 to control the operation of the corresponding fuel cell stack 31. As shown in FIG. 1, the electronic control units 80 are collectively installed at one end of the fuel cell units 20 in the arrangement direction (left-right direction). Each electronic control unit 80 is configured as a microprocessor centered around a CPU, and in addition to the CPU, has ROM, RAM, input / output ports, etc. Detection signals from the flow sensor 45 of the corresponding fuel supply system 40, the flow sensor 55 of the corresponding oxidant supply system 50, etc. are input to the electronic control unit 80 via an input port. Meanwhile, the electronic control unit 80 outputs control signals to the fuel blower 43 of the corresponding fuel supply system 40, the air blower 53 of the corresponding oxidant supply system 50, the drain valve 67 of the corresponding circulation system 60, etc. via an output port.

[0029] In this embodiment, the fuel cell unit 20 has a plurality (M) of fuel cell stacks 31 connected in series, and the fuel cell system 10 has a plurality (N) of fuel cell units 20 connected in series such that each fuel cell stack 31 is connected in series between the plurality of fuel cell units 20. As a result, the fuel cell system 10 has N×M fuel cell stacks 31 connected in series, thereby enabling a large power generation output. Therefore, the fuel cell system 10 can meet various power generation output requirements simply by changing the number of connected fuel cell units 20. Furthermore, the fuel cell unit 20 includes a plurality of sets of power generation modules 30 (fuel cell stacks 31), fuel supply systems 40 (fuel blower subassemblies 42), oxidant supply systems 50 (air blower subassemblies 52), and circulation systems 60 (condenser 62 and condensed water tank subassemblies 65), each of which has the same configuration. This allows the individual sizes of the components (auxiliaries) to be reduced, making it possible to accommodate them in the limited space of the fuel cell unit 20. As a result, the fuel cell system 10 can be made more compact while still supporting a large power generation output. Furthermore, costs can be significantly reduced through mass production.

[0030] As described above, the multiple power generation modules 30 housed in one fuel cell unit 20 are arranged side by side in one direction (vertically), and the multiple fuel supply systems 40 (fuel blower subassemblies 42) are arranged facing the corresponding power generation modules 30. Therefore, the same fuel gas piping 41, the same fuel off-gas piping 61, the same return piping 63, etc. can be used for each power generation module 30. This allows the piping length of the return piping 63, the piping length of the fuel off-gas piping 61, and the piping length of the fuel gas piping 41 downstream of the fuel blower 43 to be the same for each power generation module 30, thereby enabling the pressure and flow rate of the gas flowing through the fuel supply line (fuel gas piping 41, fuel off-gas piping 61, and return piping 63) to be the same. As a result, the specifications of each component of the fuel supply system 40 can be made the same, thereby reducing costs. Furthermore, each electronic control unit 80 does not need to individually adjust control logic or parameters for each power generation module 30, making control easier. Furthermore, the air blower subassemblies 52 of the multiple oxidant supply systems 50 and the condensed water tank subassemblies 65 of the multiple circulation systems 60 are installed together in the empty space at the bottom of the frame 21, thereby reducing dead space and making the fuel cell unit 20 more compact.

[0031] Furthermore, because hydrogen gas is used as the fuel gas, the power generation module 30 does not require a reformer for reforming (steam reforming) the raw fuel gas (natural gas or LP gas) or a supply of water (steam). In this embodiment, the fuel off-gas from the anode outlet is passed through a condenser 62 outside the power generation module 30 to remove at least a portion of the water vapor contained in the fuel off-gas before being returned to the fuel supply system 40 (fuel gas piping 41), thereby improving the power generation efficiency of the fuel cell stack 31. Furthermore, the remainder of the fuel off-gas from which at least a portion of the water vapor has been removed is supplied to the combustor 32, thereby further improving the combustibility of the fuel off-gas in the combustor 32. As a result, the efficiency of the entire system can be improved.

[0032] In the above-described embodiment, the plurality of power generation modules 30 included in the fuel cell unit 20 are arranged in a vertical line, but may also be arranged in a horizontal line.

[0033] In the above-described embodiment, the multiple fuel supply systems 40 (fuel blower subassemblies 42) provided in the fuel cell unit 20 are installed so as to face the corresponding power generation modules 30. However, the multiple fuel supply systems 40 may be installed in positions that form pairs with the corresponding power generation modules 30, and may be, for example, above or below the power generation modules 30. However, it is desirable that the multiple fuel supply systems 40 be installed near the corresponding power generation modules 30 to facilitate piping arrangement, etc.

[0034] In the above-described embodiment, the oxidant supply system 50 (air blower subassembly 52) is installed in the empty space below the power generation module 30. However, the oxidant supply system 50 may be installed in any empty space within the frame 21. For example, the oxidant supply system 50 (air blower subassembly 52) may be installed so as to face the power generation module 30 on the opposite side from the fuel supply system 40. In this case, the air inlet AI may be formed on the surface of the power generation module 30 (module case 35) that faces the oxidant supply system 50.

[0035] In the above-described embodiment, the fuel cell system 10 is configured by connecting a plurality of fuel cell units 20 having the same configuration, but it may also be configured by a single fuel cell unit 20.

[0036] Furthermore, in the above-described embodiment, the multiple fuel cell units 20 included in the fuel cell system 10 are connected in series, but they may also be connected in parallel. That is, the multiple fuel cell units 20 may be linked together so that the multiple fuel cell stacks 31 connected in series within the fuel cell unit 20 are connected in parallel between the fuel cell units 20. In this case, repairs and inspections can be performed on each fuel cell unit 20 while the fuel cell system 10 is operating. For example, if one of the fuel cell units 20 fails, the failed fuel cell unit 20 can be isolated from the fuel cell system 10, and the fuel cell system 10 can continue to operate.

[0037] A large-scale system may also be configured in which multiple fuel cell systems 10 are connected. In this case, the multiple fuel cell systems 10 may be connected in series. That is, the multiple fuel cell systems 10 may be connected such that the fuel cell stacks 31 connected in series between the fuel cell units 20 are further connected in series between the fuel cell systems 10. In this case, if the number of fuel cell stacks 31 included in one fuel cell unit 20 is M, the number of fuel cell units 20 included in one fuel cell system 10 is N, and the number of connected fuel cell systems 10 is L, then M×N×L fuel cell stacks 31 will be connected in series, thereby meeting the demand for even greater power generation output. Furthermore, the multiple fuel cell systems 10 included in the large-scale system may be connected in parallel. In this case, just like a fuel cell system 10 including multiple fuel cell units 20 connected in parallel, repairs and inspections can be performed on each fuel cell system 10 while the large-scale system is operating.

[0038] In the above-described embodiment, the fuel cell system 10 supplies hydrogen gas as the fuel gas to the anode of the fuel cell stack 31. However, ammonia gas may also be supplied. The ammonia gas supplied to the anode is decomposed into hydrogen gas and nitrogen gas by the action of the anode catalyst. The fuel cell stack 31 generates electricity through an electrochemical reaction between the hydrogen gas decomposed at the anode and oxygen in the oxidant gas (air) supplied to the cathode. In this case, as shown in FIG. 13(a), an ammonia supply source 1b, such as an ammonia tank, is connected to the fuel pipe 25 via an on-off valve 26b as the fuel supply source 1. During startup of the fuel cell system 10, ammonia gas may be supplied to the combustor 32 via the anode of the fuel cell stack 31, the fuel off-gas pipe 61, and the combustion gas pipe 64 in this order, and an oxidant gas may be supplied to the combustor 32 via the cathode of the fuel cell stack 31 to combust the mixed gas of ammonia gas and oxidant gas in the combustor 32, thereby warming up the fuel cell stack 31. 13(b), a decomposition catalyst 28 for decomposing ammonia gas into hydrogen gas and nitrogen gas and a heater 29 for heating the decomposition catalyst 28 may be installed in the fuel supply pipe 25, and at startup, ammonia gas from the ammonia supply source 1b may be decomposed into hydrogen gas and nitrogen gas by the decomposition catalyst 28 before being supplied to the combustor 32. Also, as shown in FIG. 13(c), a hydrogen supply source 1a and an ammonia supply source 1b may be connected in parallel to the fuel pipe 25, and on-off valves 26a and 26b may be installed at the outlets of the hydrogen supply source 1a and the ammonia supply source 1b, respectively, so that at startup, the on-off valve 26a is opened and the on-off valve 26b is closed to supply hydrogen gas from the hydrogen supply source 1a to the combustor 32, and during power generation, the on-off valve 26a is closed and the on-off valve 26b is opened to supply ammonia gas from the ammonia supply source 1b to the anode of the fuel cell stack 31.

[0039] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0040] The present disclosure is applicable to the fuel cell system manufacturing industry and the like. [Explanation of symbols]

[0041] 1 fuel supply source (hydrogen supply source), 10 fuel cell system, 30 power generation module, 31 fuel cell stack, 35 module case, 40 fuel supply system (hydrogen supply system), 41 fuel gas piping (hydrogen supply line), 43 fuel blower (hydrogen blower), 60 circulation system, 62 condenser (heat exchanger), 62a fuel off-gas inlet (hydrogen off-gas inlet), 63 reflux piping (reflux line), 64 combustion gas piping (combustion gas line), 66 condensate tank, 68 condensate piping (condensate line), GI fuel gas inlet, FO fuel off-gas outlet (hydrogen off-gas outlet), CI combustion gas inlet, J2 branch point.

Claims

1. a power generation module including a fuel cell stack that generates power using a fuel gas, which is at least one of hydrogen gas and ammonia gas, supplied to an anode and an oxidant gas that is supplied to a cathode, and a heat-insulating module case that houses the fuel cell stack; a fuel supply system including a fuel supply line connected to a fuel inlet of the power generation module connected to the inlet of the anode and to a fuel supply source, and a fuel blower provided in the fuel supply line; a circulation system including: a fuel off-gas line connected to a fuel off-gas outlet of the power generation module connected to an outlet of the anode; a heat exchanger provided in the fuel off-gas line; and a reflux line connected to the fuel supply line and a downstream side of the heat exchanger in the fuel supply line; a condensed water line that branches off from the fuel off-gas line at a downstream side of the heat exchanger and discharges condensed water obtained by condensing water vapor contained in the fuel off-gas in the heat exchanger; Equipped with the reflux line is connected to the fuel supply line at a position above a branch point between the fuel off-gas line and the condensed water line. Fuel cell system.

2. 2. The fuel cell system according to claim 1, a condensed water tank that receives and stores condensed water from the condensed water line, The condensed water tank is located below the branch point. Fuel cell system.

3. 3. The fuel cell system according to claim 1, a fuel off-gas inlet of the heat exchanger into which the fuel off-gas discharged from a fuel off-gas outlet of the power generation module is introduced is located below the fuel off-gas outlet; Fuel cell system.

4. 3. The fuel cell system according to claim 1, the power generation module includes a combustion section that is housed in the module case and combusts combustible gas introduced through a combustion gas inlet; the circulation system includes a combustion gas line connected to a combustion gas inlet of the power generation module, and distributes the fuel off-gas that has passed through the heat exchanger in the fuel off-gas line to the reflux line and the combustion gas line; the fuel blower and the combustion gas inlet of the power generation module are located above the branch point; Fuel cell system.

Images