JP2024046541A - Hot module for fuel cell system - Google Patents

Abstract

[Problem] To provide a hot module for a fuel cell system that makes it easy to maintain the operating temperature of a cell stack within an appropriate range. [Solution] The hot module for a fuel cell system includes a fuel cell stack and a cooling body through which cooling air flows, and the cooling body is installed near the cell stack, and the amount of heat inside the hot module is controlled by adjusting the flow rate of the cooling air introduced into the cooling body. [Selected Figure] Figure 1

Description

The present invention relates to a hot module for a fuel cell system.

Traditionally, various types of fuel cells have been developed as power generation devices that emit less environmentally harmful substances and have superior power generation efficiency compared to gas turbine generators and gas engine generators. In particular, solid oxide fuel cells (SOFCs) can achieve a high power generation efficiency of over 50%, and are therefore used to generate power over a wide range of outputs, from industrial to domestic use.

There are two types of fuel cell systems: a reformed type that uses methane-containing gas such as city gas as the raw fuel, and a non-reformed type that uses hydrogen as the raw fuel.However, as the hydrogen supply infrastructure is still under development in Japan, the former is has become the mainstream. In a reforming fuel cell system, a fuel cell stack (hereinafter sometimes simply referred to as a cell stack), which is the core of power generation, and auxiliary equipment necessary for fuel reforming, gas preheating, etc. are packaged together, and thermally It constitutes a self-supporting hot module. As disclosed in Patent Documents 1 to 3, the hot module includes a plurality of cell stacks depending on the power generation output.

Special Publication No. 2014-507759 JP 2021-15674 Publication JP 2021-12806 A

Thanks to improvements in materials and manufacturing methods, the operating temperature of SOFC cell stacks has been reduced from 700-900°C to 500-700°C in recent years. This difference in operating temperature is mainly due to the energy loss of the power generation cells. In other words, while it can be said that power generation losses have been improved in recent cell stacks, when power generation cells are used for a long period of time, the activity of the solid electrolyte and electrode materials decreases, and the interconnectors and glass seals deteriorate over time, causing the energy loss to increase compared to the initial state. This causes the operating temperature of the cell stack to gradually rise and eventually go outside the appropriate range. If the cell stack is continued to be used when the operating temperature is outside the appropriate range, it may significantly deteriorate the fuel utilization rate or impair the thermal balance of the hot module.

In Patent Document 3, therefore, the cathode air (oxidant-containing gas) is cooled with cooling water before being introduced into the hot module, and the low-temperature cathode air is supplied to the cell stack. With this configuration, excess heat inside the cell stack is discharged together with the cathode off-gas, and the operating temperature of the cell stack is maintained within an appropriate range. However, the configuration of Patent Document 3 has the following concerns:

The first concern is that while the operating temperature of the cell stack is indirectly controlled by external cooling of the cathode air, the amount of heat dissipated from the cell stack must also be completely controlled. As there is no means of releasing the excess heat accumulated inside the hot module, special measures are required, such as covering the cell stack itself with insulating material, which increases the assembly labor and material costs of the hot module. In addition, as the radiant heat transfer from the cell stack is not used for thermal self-sustaining reactions such as the steam reforming reaction of the raw fuel gas, a large amount of surplus waste heat is generated, making it difficult to establish a mono-generation type SOFC system.

The second concern is that the supply of cathode air that has not been preheated to the operating temperature of the cell stack acts to lower the temperature of the solid electrolyte. Therefore, even if the power generation performance of the cell stack has not changed significantly from the initial state and the energy loss of the power generation cells is minimal, the low temperature of the cathode air may adversely affect the ion permeability of the solid electrolyte, resulting in a decrease in the amount of power generation reaction.

The third point of concern is that incidental equipment for circulating cooling water (circulation pump, buffer tank, etc.) and cooling water re-cooling equipment (cooling tower, chiller, etc.) are required. As a result, the initial cost of the system is high, and the power consumption of these facilities can significantly reduce power generation efficiency. In addition, in a water cycle that is open to the atmosphere, appropriate water quality management, such as adding disinfectants and blowdowns, is essential in order to suppress the proliferation of bacteria (particularly Legionella bacteria) in the water.

The present invention was made in consideration of the above problems, and aims to provide a hot module for a fuel cell system that makes it easy to maintain the operating temperature of the cell stack within an appropriate range.

A hot module of a fuel cell system according to the present invention includes a fuel cell stack and a cooling body through which cooling air flows, and the cooling body is installed near the cell stack and introduced into the cooling body. By adjusting the flow rate of cooling air, the amount of heat inside the hot module is controlled. According to this configuration, since there is a means for discharging excess heat accumulated inside the hot module, it becomes easy to maintain the operating temperature of the cell stack within an appropriate range.

More specifically, the above configuration may be such that a plurality of fuel cell stacks are integrated to form a cell stack assembly, and the cooling body is installed near the cell stack assembly. Further, more specifically, in the above configuration, the cooling body is configured such that the flow direction of the cooling air flowing through the cooling body and the flow direction of the anode fuel flowing through the inside of the cell stack are substantially the same. As such, it may be installed near the cell stack or the cell stack assembly. Note that "substantially the same direction" here means that the reference flow direction along the straight line connecting the inlet reference point and outlet reference point of one fluid and the reference flow direction of the other fluid are within 45 degrees. This is the case when .

More specifically, the cooling body may have a box-like or tubular shape. More specifically, the cooling body may have a structure or a filling therein that promotes turbulent flow of cooling air.

More specifically, the cell stack has a structure in which a predetermined number of flat power generating cells are stacked between a pair of end plates, and at least one of the end plates has an anode fuel inflow port, a cathode air It has an inflow port, an anode off-gas outflow port, and a cathode off-gas outflow port, and the cooling body may be installed along the plate surface of the end plate.

More specifically, the above configuration includes a manifold serving as a cathode air introduction main pipe, and a branch pipe connecting the cathode air inflow port and the manifold, and the cooling body is configured to It may be configured as a separate component.

More specifically, the above configuration may be such that at least a portion of the cooling air after passing through the cooling body is supplied to the cell stack as cathode air.

The hot module of the fuel cell system of the present invention makes it easy to maintain the operating temperature of the cell stack within an appropriate range.

1 is an explanatory diagram showing the configuration of a fuel cell system 100 according to a first embodiment. FIG. 2 is a perspective view of a hot module HM according to the first embodiment. It is a perspective view of hot module HM with a part not shown. It is a perspective view of hot module HM with a part not shown. It is a perspective view of hot module HM with a part not shown. FIG. 2 is a perspective view of a hot module HM with a portion not shown. It is a side view of hot module HM with a part not shown. It is a side view of hot module HM with a part not shown. FIG. 2 is a side view of the reformed gas generator RG according to the first embodiment. 2 is a cross-sectional side view of the reformed gas generating device RG. FIG. It is a block diagram of the burner vicinity in reformed gas generator RG. 2 is a side view of a hot module HM with a portion not shown. FIG. FIG. 1 is a perspective view of a cell stack 1 according to a first embodiment. FIG. 2 is a plan view of the cell stack 1. FIG. 2 is a cross-sectional view of the vicinity of the flanged gas port of the cell stack 1 when viewed from above. FIG. 3 is a perspective view of a stack assembly 61 according to the first embodiment. FIG. 2 is a perspective view of a stack assembly 61. FIG. 2 is an explanatory diagram of a state in which a cell stack 1 is mounted on a unit rack. FIG. 3 is an explanatory diagram of a branch pipe extending from the manifold according to the first embodiment. FIG. 2 is an explanatory diagram regarding the connection configuration of each power terminal of the cell stack 1. FIG. 2 is a perspective view of a hot module HM with a portion not shown. It is a perspective view of the hot module of 2nd Embodiment with a part not shown. FIG. 11 is a perspective view of a hot module according to a third embodiment, with a portion not shown. FIG. 13 is an explanatory diagram showing the configuration of a fuel cell system 200 according to a fourth embodiment. FIG. 3 is a perspective view of a cooling body 110 according to a fourth embodiment. FIG. 3 is a cross-sectional view of the cooling body 110. FIG. 11 is a schematic perspective view of an offset fin 117. FIG. 13 is an explanatory diagram of a configuration example within a hot module according to the fourth embodiment; FIG. 13 is an explanatory diagram of another example of the configuration inside the hot module according to the fourth embodiment. FIG. 3 is an explanatory diagram regarding the flow direction of anode fuel. It is a perspective view of cooling body 110a concerning a 5th embodiment. FIG. 2 is an explanatory diagram of the first heat absorption plate 111 when viewed from above. FIG. 3 is an explanatory diagram of the second heat absorption plate 112 when viewed from above. FIG. 13 is an explanatory diagram of a first heat absorbing plate and a second heat absorbing plate integrated together. FIG. 13 is an explanatory diagram showing the configuration of a fuel cell system 200a according to a sixth embodiment.

Hereinafter, each embodiment of the present invention will be described with reference to each drawing.

1. First embodiment <Outline of configuration of fuel cell system>
First, an outline of the configuration of a fuel cell system 100 according to a first embodiment of the present invention will be described. Fig. 1 is an explanatory diagram showing the configuration of the fuel cell system 100. As shown in Fig. 1, the fuel cell system 100 includes a plurality of cell stacks (fuel cell stacks) 1, a reformer 2, a burner 3, an evaporator 4, an air preheater 5, an anode off-gas cooler 6, an anode off-gas condenser 7, a CO oxidizer (carbon monoxide oxidizer) 8, a condensed water recovery tank 9, a first raw fuel blower 10, a first air blower 11, a water pump 12, a second raw fuel blower 13, a second air blower 14, a power conditioner 15, a system controller 16, and a third air blower 17.

In this embodiment, a total of eight cell stacks 1 are provided, including those not shown in FIG. 1. In the following description, the fuel cell system 100 may be referred to simply as the "system."

The fuel cell system 100 also includes the following lines (pipes): a raw fuel line La, a mixed gas line Lb, an anode fuel line Lc, an anode offgas line Ld, a cathode air line Le, a cathode offgas line Lf, a combustion gas line Lg, a burner cooling air line Lh, a reforming water line Li, a start-up air line Lj, a cooling air line Lk, and a condensed water recovery line Lw.

The anode fuel line Lc includes a first distribution manifold Ma that serves as the inlet pipe for the anode fuel, and the cathode air line Le includes a second distribution manifold Mb that serves as the inlet pipe for the cathode air. These distribution manifolds Ma and Mb have an inlet and multiple outlets corresponding to each cell stack 1, and the fluid that flows into the inlet flows out from each of the outlets.

The anode off-gas line Ld includes a first collection manifold Mc that serves as a main pipe for discharging anode off-gas, and the cathode off-gas line Lf includes a second collection manifold Md that serves as a main pipe for discharging cathode off-gas. These collection manifolds Mc, Md have a plurality of inlets and outlets corresponding to each cell stack 1, and allow the fluid that has entered each inlet to flow out from the outlet.

The combustion gas line Lg includes a heat radiator Za and a combustion gas pipe Zb. The cooling air line Lk includes a cooling pipe Zc and a collecting pipe Lk1.

The raw fuel line La is a pipe line that connects the fuel intake port E1 and the burner 3, and a second raw fuel blower 13 is arranged in this pipe line. The second raw fuel blower 13 is a device that boosts the pressure of the raw fuel gas (for example, methane-containing gas such as city gas 13A) Gf taken in from the fuel intake port E1 and sends it to the downstream side of the raw fuel line La. Generally, it is activated during system startup operation.

The mixed gas line Lb is a pipe line that connects the fuel intake port E2 and the reformer 2, and in this pipe line, in order from the upstream side, there are a first raw fuel blower 10, an evaporator 4, and a first bellows type. An expansion joint B1 is arranged. The first raw fuel blower 10 is a device that boosts the pressure of the raw fuel gas Ga taken in from the fuel intake port E2 and sends it to the downstream side of the mixed gas line Lb, and is typically driven during power generation operation of the system. .

The anode fuel line Lc is a pipe line that connects the reformer 2 and the anode of each cell stack 1. More specifically, the anode fuel line Lc includes, in order from the upstream side, a pipe connecting the reformer 2 and the inlet of the first distribution manifold Ma, a first distribution manifold Ma, and a pipe line connecting the reformer 2 and the inlet of the first distribution manifold Ma. It has eight pipes (branch pipes of the first distribution manifold Ma) connecting each outlet and the anode of each cell stack 1.

The anode off-gas line Ld is a conduit that connects the anode of each cell stack 1 and the burner 3. More specifically, the anode off-gas line Ld consists of eight pipes (branch pipes of the first collection manifold Mc) connecting the anode of each cell stack 1 and each inlet of the first collection manifold Mc in order from the upstream side. ), a first collection manifold Mc, and a pipe line (hereinafter referred to as "pipe line Ld1") connecting the outlet of the first collection manifold Mc and the first gas cylinder 31 (described later) of the burner 3. A second bellows-type expansion pipe joint B2, an anode off-gas cooler 6, an anode off-gas condenser 7, and a steam/water separator Sa are arranged in order from the upstream side in the middle of the pipe Ld1.

The cathode air line Le is a conduit connecting the air intake port E3 and the cathode of each cell stack 1. To explain more specifically, the cathode air line Le includes, in order from the upstream side, a conduit connecting the air intake port E3 and the inlet of the second distribution manifold Mb (hereinafter referred to as "pipe line Le1"), a second It has a distribution manifold Mb and eight pipes (branch pipes of the second distribution manifold Mb) connecting each outlet of the second distribution manifold Mb and the cathode of each cell stack 1.

In the middle of the pipe Le1, from the upstream side, a first air blower 11, an anode off-gas cooler 6, an air preheater 5, and a third bellows type expansion joint B3 are arranged. The first air blower 11 is a device that boosts the pressure of the air Aa taken in from the air intake E3 and sends it to the downstream side of the cathode air line Le, and is typically driven during power generation operation of the system. Furthermore, in the pipe Le1, a bypass route Le2 is provided that bypasses the anode off-gas cooler 6 and the air preheater 5 so as to connect the midpoint between the air intake E3 and the anode off-gas cooler 6, and the midpoint between the air preheater 5 and the third bellows type expansion joint B3.

The cathode off-gas line Lf is a conduit that connects the cathode of each cell stack 1 and the burner 3. More specifically, the cathode off-gas line Lf consists of eight pipes (branch pipes of the second collection manifold Md) connecting the cathode of each cell stack 1 and each inlet of the second collection manifold Md in order from the upstream side. ), a second collection manifold Md, and a pipe line (hereinafter referred to as "pipe line Lf1") connecting the outlet of the second collection manifold Md and the second gas cylinder 32 (described later) of the burner 3.

The combustion gas line Lg is a pipeline connecting the burner 3 and the gas exhaust port D1. More specifically, the combustion gas line Lg has, in order from the upstream side, a heat radiation tube Za, a pipeline connecting the heat radiation tube Za and the combustion gas pipe Zb, the combustion gas pipe Zb, and a pipeline connecting the combustion gas pipe Zb and the gas exhaust port D1 (hereinafter referred to as "pipe Lg1"). In the middle of the pipeline Lg1, in order from the upstream side, a fourth bellows-type expansion joint B4, an air preheater 5, a CO oxidizer 8, and an evaporator 4 are arranged.

The burner cooling air line Lh is a pipe that connects the pipe Le1 and the starting air line Lj, and a flow rate adjusting means (not shown, such as an orifice) is provided in this pipe. To explain more specifically, the burner cooling air line Lh branches at the midpoint of the pipe line Le1 connecting the first air blower 11 and the anode off-gas cooler 6, and is branched at the midpoint of the pipe line Le1 connecting the first air blower 11 and the anode off-gas cooler 6, and is branched at the downstream side of the second air blower 14 for starting. This is a conduit that joins the air line Lj, and is configured so that a minute flow rate of air Ab flows toward the burner 3 when the first air blower 11 is driven. Although details will be described later, depending on the combustion temperature of the burner 3, the burner cooling air line Lh can be omitted.

The cooling air line Lk is a conduit that connects the air intake port E5 and a predetermined location of the conduit Lg1 (a location between the evaporator 4 and the gas outlet D1), and there is a A third air blower 17 and a cooling pipe Zc are arranged in this order. The third air blower 17 is a device that boosts the pressure of the cooling air Ad taken in from the air intake port E5 and sends it to the downstream side of the cooling air line Lk.

The reforming water line Li is a pipe that connects the condensed water recovery tank 9 and the evaporator 4, and a water pump 12 is disposed in this pipe. The water pump 12 is a device that sends the condensed water Wb stored in the condensed water recovery tank 9 to the downstream side of the reforming water line Li as reforming water Wa.

The startup air line Lj is a pipe that connects the air intake E4 and the pipe Lf1, and a second air blower 14 is disposed in this pipe. The second air blower 14 is a device that pressurizes the air Ac taken in from the air intake E4 and sends it downstream of the startup air line Lj, and is typically driven during start-up operation of the system.

The condensed water recovery line Lw is a conduit that connects the steam/water separation section Sa and the condensed water recovery tank 9 arranged in the middle of the conduit Ld1. The steam/water separator Sa is a member that separates the condensed water Wb generated in the anode off-gas condenser 7 from the anode off-gas Gd, and the separated condensed water Wb flows down into the condensed water recovery line Lw. The tip of the condensed water recovery line Lw is opened to the gas phase without being immersed in the water phase of the condensed water recovery tank 9 so that the amount of condensation does not increase or decrease due to the influence of the temperature of the stored condensed water Wb. Ru. Note that the reason why the tip of the condensed water recovery line Lw is not immersed in the water phase portion is to keep the flow rate of the anode off gas Gd sent to the burner 3 unchanged. In particular, this configuration is effective when the anode off-gas Gd after separating the condensed water Wb is recycled to the primary side of the cell stack or used for power generation in the subsequent cell stack. For example, a T-shaped pipe in which a straight pipe section is arranged horizontally and a branch pipe section is arranged downward is used for the steam/water separation section Sa. Further, a small-capacity cylindrical container vertically arranged can also be used as the steam/water separation section Sa.

The cell stack 1 is a power generating unit composed of a solid oxide fuel cell (SOFC). A solid oxide fuel cell is a high-temperature operating fuel cell in which the solid electrolyte, anode, and cathode that make up the power generating cell are all made of ceramics, and a power generating unit in which a certain number of power generating cells are integrated via a metal interconnect material (also called a separator material) is called a cell stack. The battery output of the cell stack 1 is adjusted by the power conditioner 15 before being supplied.

The reformer 2 uses steam to reform the raw fuel gas Ga, generating reformed gas Gc, which is sent to the downstream side. The reformer 2 has a catalyst for steam reforming, and reacts methane contained in the raw fuel gas Ga with steam to generate reformed gas Gc containing carbon monoxide and hydrogen. Although steam reforming is an endothermic reaction, the heat supply from the burner 3 enables the reformer 2 to stably generate reformed gas Gc.

The burner 3 burns the inflowing gas to generate heat, and discharges the combustion gas Gg generated by the combustion to the combustion gas line Lg. The evaporator 4 is a device that indirectly exchanges heat between the reformed water Wa and the combustion gas Gg (heat source fluid), and simultaneously evaporates the reformed water Wa and heats the raw fuel gas Ga through heat exchange with the combustion gas Gg. play a role.

The air preheater 5 and the anode off-gas cooler 6 are both heat exchangers that perform indirect heat exchange between low-temperature fluid and high-temperature fluid. The air preheater 5 serves to preheat the air Aa in the cathode air line Le by heat exchange with the combustion gas Gg, and the anode off-gas cooler 6 serves to cool the anode off-gas Gd by heat exchange with the air Aa in the cathode air line Le.

The anode off-gas condenser 7 plays a role of cooling the anode off-gas Gd and condensing water vapor contained in the anode off-gas Gd. Note that, although the anode off-gas condenser 7 in this embodiment is an air-cooled heat exchanger, a water-cooled heat exchanger may be used instead, and a cogeneration type system in which heat is recovered thereby may be used.

The CO oxidizer 8 is a device that brings harmful carbon monoxide contained in the combustion gas Gg into contact with a catalyst and converts it into harmless carbon dioxide. The CO oxidizer 8 does not operate if the oxidation reaction in the burner 3 is complete, and only operates if the oxidation reaction in the burner 3 is incomplete.

The condensed water recovery tank 9 recovers the condensed water Wb discharged from the water-air separation section Sa and makes it reusable as reforming water Wa. The condensed water recovery tank 9 is provided with a water level detector Sb and a drain valve Sc to adjust the water level of the stored reforming water Wa to a predetermined range. When the water level detector Sb detects the upper limit water level, the drain valve Sc is opened, whereas when the water level detector Sb detects the lower limit water level, the drain valve Sc is closed. In this way, the required amount of reforming water Wa is secured in the condensed water recovery tank 9. In addition, in order to prevent the anode off-gas Gd from leaking to the outside during the draining operation of the reforming water Wa, the drain position of the drain valve Sc is set near the bottom of the condensed water recovery tank 9.

The power conditioner 15 is a device for converting the power generated by the cell stack 1 into a state that can be used in business activities and social life. The power conditioner 15 has a DC/DC converter (boost circuit) that boosts the DC voltage output from the cell stack 1, a grid-connected inverter (voltage conversion circuit) that converts the DC voltage boosted by the DC/DC converter into AC voltage synchronized with the grid power supply, an output current control unit (output control circuit) that controls the output current (sweep current) of the cell stack 1, and a drive power supply unit (auxiliary circuit) for supplying drive power to auxiliary equipment.

The grid-connected inverter described above is electrically connected to a switchboard of a commercial power system installed in a building. The grid-connected inverter and the switchboard can be switched between parallel and disconnection via a grid-connection switch. A commercial power source and a plurality of distribution panels are electrically connected to the distribution panel. Load devices used within the building, such as lighting equipment, power equipment, and electrical outlets, are electrically connected to the distribution board.

The drive power supply unit is connected to each of the blowers 10, 11, 13, 14, 17, the water pump 12, the spark rod (first electrode rod described later) of the burner 3, and the like, and provides drive power to these auxiliary devices. When the auxiliary devices are DC-driven, the drive power supply unit is circuit-configured to supply, for example, AC/DC converted power from the output of the grid-connected inverter, AC/DC converted power from the input from the commercial power source, or DC/DC converted power from the output of the cell stack 1. On the other hand, when the auxiliary devices are AC-driven, the drive power supply unit is circuit-configured to supply, for example, the output power of the grid-connected inverter or the input power from the commercial power source. The above-mentioned auxiliary devices are driven using the commercial power source during startup and shutdown operations of the system, and are driven using the generated power during power generation operations of the system.

The system controller 16 is a device that controls the operation of auxiliary equipment such as a blower and the power conditioner 15 (ie, system operation) according to a control program created and stored in advance.

Further, as shown by the broken line frame in FIG. 1, each cell stack 1, reformer 2, burner 3, each manifold Ma to Md, heat radiation cylinder Za, combustion gas pipe Zb, and cooling pipe Zc are connected to a hot module described later. It is arranged in a first region R1 inside the first box X1 (see FIG. 3) in the HM. On the other hand, the evaporator 4, air preheater 5, anode off-gas cooler 6, and CO oxidizer 8 are located outside the first box X1 and inside a second box X2 (see FIG. 3), which will be described later. 2 area R2. Note that the anode off-gas condenser 7, condensed water recovery tank 9, blowers 10, 11, 13, 14, 17, water pump 12, power conditioner 15, and system controller 16 are installed outside the hot module HM (in the room temperature area). ).

<Outline of fuel cell system operation>
Next, an overview of the operation of the fuel cell system 100 will be described with reference to Fig. 1. The raw fuel gas Ga supplied from the fuel inlet E2 into the mixed gas line Lb is sent to the rear stage by the action of the first raw fuel blower 10. In parallel with the supply of the raw fuel gas Ga, the reforming water Wa supplied from the condensed water recovery tank 9 into the reforming water line Li has its amount adjusted by the water pump 12 and flows into the mixed gas line Lb.

The reforming water Wa flows into the evaporator 4 together with the raw fuel gas Ga in the mixed gas line Lb, where it is heated by heat exchange to become water vapor (superheated steam). The water vapor mixes with the heated raw fuel gas Ga and flows into the reformer 2 as mixed gas Gb.

The reformer 2 reforms raw fuel gas Ga using water vapor in mixed gas Gb, generates reformed gas Gc, and sends the reformed gas Gc to the subsequent stage side. The reformed gas Gc sent out from the reformer 2 is distributed to the anode of each cell stack 1 through the anode fuel line Lc.

Meanwhile, in parallel with the supply of the raw fuel gas Ga described above, air Aa is supplied from the air intake E3 into the cathode air line Le. The air Aa in the cathode air line Le is sent to the rear stage by the action of the first air blower 11. This air Aa is heated by heat exchange in the anode off-gas cooler 6, and is further heated by heat exchange in the air preheater 5, and then distributed to the cathodes of each cell stack 1. In addition, in order to adjust the temperature of the air Aa, it is also possible to flow a part of the air Aa, air Aa1, into the cathodes of each cell stack 1 via the bypass path Le2.

Furthermore, air Ab is supplied into the burner cooling air line Lh in synchronization with the supply of air Aa to the cathode. The air Ab in the burner cooling air line Lh is sent to the burner 3 by the action of the first air blower 11. This air Ab acts as a coolant that lowers the combustion temperature of the burner 3, preventing overheating and burning of the flame stabilizer 33 (described below). Note that if the flame temperature is maintained at a level that does not cause overheating or burning of the flame stabilizer 33 without supplying air Ab, the burner cooling air line Lh may be omitted.

Each cell stack 1 generates electricity using the reformed gas Gc that has flowed into the anode and the air Aa that has flowed into the cathode, and discharges anode off gas Gd from the anode to the anode off gas line Ld, and discharges the anode off gas Gd from the cathode to the cathode off gas line Lf. Discharge off-gas Ge. The anode off-gas Gd contains fuel components that have not reacted at the anode, and the cathode off-gas Ge contains oxygen that has not reacted at the cathode.

The anode off gas Gd discharged from each cell stack 1 to the anode off gas line Ld is collected in the first collection manifold Mc, cooled by heat exchange in the anode off gas cooler 6, and flows into the anode off gas condenser 7. . In the anode off-gas condenser 7, the anode off-gas Gd is cooled to below the dew point temperature, and water vapor contained in the anode off-gas Gd is condensed.

The anode off-gas Gd that has passed through the anode off-gas condenser 7 is sent to the water-air separation section Sa where it is separated into water and air, and the condensed water Wb is collected in the condensed water recovery tank 9. The condensed water Wb collected in the condensed water recovery tank 9 is reused as reformed water Wa, as described above. The uncondensed portion of the anode off-gas Gd (anode off-gas Gd after water-air separation) is sent to the burner 3.

The cathode off gas Ge discharged from each cell stack 1 to the cathode off gas line Lf is collected in the second collection manifold Md, and then mixed with the air Ab that has flowed in through the burner cooling air line Lh in the pipe Lf1, Sent to burner 3. Further, depending on the operating state of the system, the raw fuel gas Gf supplied from the fuel intake port E1 is sent to the burner 3 via the raw fuel line La, and the air Ac supplied from the air intake port E4 is sent to the burner 3. , is sent via the starting air line Lj.

The burner 3 receives a first burner gas Gx, which is a raw fuel gas Gf and/or an anode off gas Gd, and a second burner gas Gy, which is air Ac and/or a cathode off gas Ge, and burns them to generate heat. to occur. In other words, the first burner gas Gx is either a mixed gas of raw fuel gas Gf and anode off gas Gd, or one of raw fuel gas Gf and anode off gas Gd, and which state it is in depends on the operating state of the system. etc. may change. In addition, the second burner gas Gy is either a mixed gas of air Ac and cathode off gas Ge, or one of air Ac and cathode off gas Ge, and which state it is in varies depending on the operating state of the system, etc. obtain. That is, the state of the gas supplied to the burner 3 changes as appropriate depending on the startup operation, power generation operation (full load operation or partial load operation), shutdown operation, etc. of the system.

The raw fuel gas Gf is a type of hydrocarbon-containing gas. On the other hand, air Ac is a type of oxidant-containing gas. During the combustion operation of the burner 3, air Ab is continuously supplied from the burner cooling air line Lh to adjust the combustion temperature.

The combustion gas Gg generated by combustion in the burner 3 is sent to the combustion gas line Lg, passes through the heat radiation tube Za, the combustion gas pipe Zb, the air preheater 5, the CO oxidizer 8, and the evaporator 4 in order, and is discharged from the gas exhaust port D1 to the outside of the hot module HM. As will be described in more detail later, the heat radiation tube Za and the combustion gas pipe Zb are arranged so that the reformer 2 can be effectively heated using the combustion gas Gg. In addition, the combustion gas Gg in the combustion gas line Lg is used for heat exchange as it passes through the air preheater 5 and the evaporator 4, and if it contains carbon monoxide, the carbon monoxide is converted to carbon dioxide as it passes through the CO oxidizer 8.

The cooling air Ad supplied to the cooling air line Lk from the air intake E5 serves to cool the inside of the hot module HM as it passes through the cooling pipe Zc. As described below, the cooling pipe Zc is installed near the cell stack 1, and the cooling air Ad can effectively cool the cell stack 1 and the main bus bar 78a and sub bus bar 78b described below. The cooling air Ad then passes through the collection pipe Lk1 and is finally discharged to the outside of the hot module HM from the gas exhaust port D1 together with the combustion gas Gg.

Further, in the fuel cell system 100, the amount of heat (temperature) inside the hot module HM is controlled by adjusting the flow rate of the cooling air Ad introduced into the cooling pipe Zc. As an example, the fuel cell system 100 drives the third air blower 17 when the internal temperature of the hot module HM (for example, the maximum value of the surface temperature of the end plate of each cell stack 1) exceeds the upper limit temperature. The rotation speed of the third air blower 17 is controlled so that the internal temperature of the third air blower 17 becomes the target temperature (a temperature lower than the upper limit temperature by a predetermined temperature). Further, the fuel cell system 100 stops the third air blower 17 when the rotational speed continues to be less than the lower limit value for a predetermined period of time. Note that as the rotational speed of the third air blower 17 increases, the flow rate of the cooling air Ad introduced into the cooling pipe Zc increases. Such control operations may be performed by the system controller 16.

Note that the cooling pipe Zc installed near the cell stack 1 can also be used to raise the temperature of the cell stack 1 during startup operation of the system. Specifically, in the startup operation of the system, first, the second raw fuel blower 13 and the second air blower 14 are driven to cause the burner 3 to burn. The combustion gas Gg produced by this combustion heats the cold reformer 2 from the outside by radiant heat transfer while flowing through the heat radiator Za and the combustion gas pipe Zb to raise its temperature. Furthermore, the combustion gas Gg becomes a heat source for the evaporator 4, and generates steam from the reformed water Wa. This water vapor sequentially flows through the cold reformer 2 and the cell stack 1, and heats these devices from the inside by thermal conduction, raising their temperature. When the combustion gas Gg discharged from the evaporator 4 has residual heat, the combustion gas Gg is caused to flow into the collection pipe Lk1 from the pipe line Lg1. As a result, the combustion gas Gg flows through the cooling pipe Zc, so that the temperature of the cold cell stack 1 can be increased by heating it from the outside by radiant heat transfer.

<Hot module>
Next, the configuration etc. of the hot module HM will be explained in more detail. FIG. 2 is a perspective view of the hot module HM. FIG. 3 is a perspective view of the hot module HM in which the first box X1, the second box X2, and a part of the plate-shaped heat insulating material 53 are not shown so that the internal structure of the hot module HM can be easily understood. . Note that the front-rear, left-right, and up-down directions (directions perpendicular to each other) in the following description are merely determined for convenience as shown in FIG. 2 and the like. In the example of this embodiment, the up-down direction coincides with the vertical direction.

As shown in FIGS. 2 and 3, the hot module HM includes a first pedestal X1a, a second pedestal X2a, a first box X1 formed on the first pedestal X1a, and a second box formed on the second pedestal X2a. X2, a plurality of (four in the example of this embodiment) first pillars 51 that support the first pedestal X1a, and a plurality of (four in the example of this embodiment) first pillars 51 that support the second pedestal X2a. Two pillars 52 are provided.

The first box X1 is housed inside the second box X2, and in this state, the plurality of first columns 51 support the first pedestal X1a at a predetermined height from the second pedestal X2a. The first box X1 is set as a first region R1 (see FIG. 1) whose internal region is a high-temperature operation region, and accommodates a first equipment group GP1 that internally undergoes a chemical reaction during power generation operation of the system. Ru. This first equipment group GP1 includes a cell stack 1, a reformer 2, and a burner 3.

The area inside the second box X2 but outside the first box X1 (below the first pedestal X1a) is set as a second region R2 (see FIG. 1), which is a low-temperature operating region, and houses a second equipment group GP2 that does not involve chemical reactions inside during power generation operation of the system. The second equipment group GP2 includes an evaporator 4 and a heat exchanger (air preheater 5 and anode off-gas cooler 6).

The second region R2 also contains a third equipment group GP3 that undergoes a chemical reaction inside only when certain conditions are satisfied during power generation operation of the system. The third equipment group GP3 includes a CO oxidizer 8 that does not operate when the oxidation reaction in the burner 3 is complete, and operates only when the oxidation reaction in the burner 3 is incomplete. Since the heat generated by the catalytic reaction of the CO oxidizer 8 is minimal, there is little problem in placing the CO oxidizer 8 in the second region R2 (low temperature operation region), which makes it possible to reduce the capacity of the first box X1.

A plate-shaped heat insulating material 53 is attached to each of the front, rear, left and right sides and the top (upper side) of the first box X1. The plate-shaped heat insulating material 53 covers almost all of the front, rear, left, right, and upper outer surfaces of the first box X1. This allows a strong heat insulating effect to be obtained, making it easy to maintain the inside of the first box X1 at a high temperature.

The space of the second region R2 (the arrangement space of the second equipment group GP2) is filled with a granular heat insulating material (not shown). Although heat conduction occurs from the first box X1, which is a high temperature operation region, to the second region R2 through the first pedestal X1a, a sufficient heat insulation effect can be obtained by filling the granular heat insulating material. Therefore, the second equipment group GP2 and its connecting piping can be configured without using expensive high temperature resistant materials.

The first pedestal X1a is provided with a pipe insertion hole (through hole), and each line (pipe) extending across the boundary between the first region R1 and the second region R2 is arranged to pass through this through hole. As a result, fluid is transferred between the first equipment group GP1 and the second equipment group GP2 through a pipe that passes through the first pedestal X1a in the vertical direction. In this manner, in this embodiment, the piping for transferring fluid between the equipment groups GP1 and GP2 is structured simply by attaching a pipe to a pipe insertion hole drilled in the first pedestal X1a, and therefore does not require special seals or the like.

Furthermore, bellows-type expansion joints may be provided in the pipelines for the fluid passing through the second equipment group GP2. The pipes connecting the pipeline penetrating the first base X1a to the heat exchanger, and the pipes connecting the heat exchangers to each other, expand and contract due to temperature changes between when the system is in a cold state and when it is operating. The thermal stress generated by this expansion and contraction can cause cracks or breaks in the pipe body and joints, which in some cases can cause serious problems such as the leakage of flammable gas. By including bellows-type expansion joints in the piping equipment used for fluid connections in the second equipment group GP2, the generation of thermal stress can be minimized, making it possible to avoid such problems.

In this embodiment, as shown in FIG. 1, at least in each of the fluid pipelines that pass through the second equipment group GP2 and extend across the boundary between the first region R1 and the second region R2, a bellows-type expansion joint that can expand and contract up and down is installed near the boundary of the second region R2. More specifically, a first bellows-type expansion joint B1 is installed near the boundary of the mixed gas line Lb, a second bellows-type expansion joint B2 is installed near the boundary of the anode off-gas line Ld, a third bellows-type expansion joint B3 is installed near the boundary of the cathode air line Le, and a fourth bellows-type expansion joint B4 is installed near the boundary of the combustion gas line Lg. In addition, a bellows-type expansion joint may be installed in each pipe that connects the heat exchangers in the second region R2.

The hot module HM is assembled, for example, in the following steps. First, the second equipment group GP2 is placed on the second pedestal X2a, and the necessary piping materials are used to install the piping between the equipment. Next, multiple first supports 51 are attached to the second pedestal X2a, and the first pedestal X1a is placed and fixed on the tip of the first supports 51. Next, a pipeline is attached to a pipe insertion hole drilled in the first pedestal X1a, and piping is installed between this pipeline and the second equipment group GP2. Next, a casing that surrounds the second equipment group GP2 is attached to the second pedestal X2a to form a semi-open second box X2, and granular insulation material is filled inside the second box X2.

Then, the first equipment group GP1 is placed on the first pedestal X1a, and piping is installed between the pipeline attached to the first pedestal X1a and the first equipment group GP1, and piping between the equipment is installed using the required piping materials. Next, a casing that surrounds the first equipment group GP1 is attached to the first pedestal X1a to form a sealed first box X1, and plate-shaped insulation material 53 is attached to the sides and top of the first box X1. A casing that surrounds the plate-shaped insulation material 53 attached to the first box X1 is attached to the semi-open second box X2 to form a sealed second box X2. By going through the above steps, the hot module HM can be easily assembled.

Figures 4 to 6 are perspective views of the hot module HM from different viewpoints. Figures 7 and 8 are side views of the hot module HM from different viewpoints. In these figures, the first box X1, the second box X2, and the plate-shaped insulation material 53 are not shown so that the internal structure of the hot module HM can be easily understood. The white arrows in Figures 5 to 8 show the flow direction of each fluid.

As shown in these figures, a cylindrical reformer 2 that stands vertically (in the vertical direction) is disposed at a substantially central position above the first pedestal X1a when viewed from above. A burner 3 is disposed at. Although details will be described later, the reformer 2, the burner 3, and the heat radiator Za are integrally configured as a reformed gas generator.

On each of the right and left sides of the reformer 2, a cell stack assembly 61 in which a plurality of (four in the present embodiment) cell stacks 1 are vertically stacked is arranged. As shown in FIG. 4, in a region sandwiched between the left and right cell stack assemblies 61 on the front side of the reformer 2, a first distribution manifold Ma and a second distribution manifold Mb are arranged to extend vertically. has been done. The first distribution manifold Ma and the second distribution manifold Mb are arranged adjacent to each other and near the cell stack assembly 61.

By arranging the first distribution manifold Ma and the second distribution manifold Mb adjacent to each other, heat exchange occurs between the surfaces of these two distribution manifolds by radiation heat transfer and convection heat transfer. In addition, by arranging each distribution manifold Ma, Mb near the cell stack assembly 61, heat exchange occurs between the surfaces of the equipment by radiation heat transfer and convection heat transfer. This makes the temperatures of the anode fuel (reformed gas Gc) and cathode air (air Aa) supplied to the cell stack 1 uniform, and also raises the temperature close to the operating temperature of the cell stack 1, allowing efficient power generation reactions to occur throughout the entire power generation cell.

As shown in FIG. 6, in the area between the left and right cell stack assemblies 61 at the rear of the reformer 2, the first collection manifold Mc and the second collection manifold Md are arranged to extend vertically. That is, the cell stack assembly 61, the first collection manifold Mc, and the second collection manifold Md are arranged to surround the outer cylinder 21 of the reformer 2.

In this way, each cell stack 1, the first collecting manifold Mc, and the second collecting manifold Md are arranged in the vicinity of the reformer 2, making it possible to efficiently provide the waste heat associated with the power generation reaction to the reformer 2. In particular, the first collecting manifold Mc has the role of actively providing the waste heat contained in the anode off-gas Gd to the reformer 2. The second collecting manifold Md also has the role of actively providing the waste heat contained in the cathode off-gas Ge to the reformer 2. This significantly increases the amount of heat absorbed in the catalyst layer in the reformer 2, improving the efficiency of the steam reforming reaction, reducing the amount of catalyst used, and enabling the reformer 2 to be made more compact.

<Reformer, burner, heat radiator>
Next, the configurations of the reformer 2, the burner 3, the heat radiating tube Za, etc. will be explained in more detail. In the example of this embodiment, the reformer 2, the burner 3, and the heat radiator Za are integrally configured as a reformed gas generator RG.

FIG. 9 shows a side view of the reformed gas generator RG, and FIG. 10 shows a cross-sectional view of the reformed gas generator RG when viewed from the side. Further, FIG. 11 shows a detailed configuration of the vicinity of the burner 3 in the reformed gas generator RG. Note that FIG. 11 schematically shows an example of the configuration of the ignition/flame detection circuit 40.

In the reformed gas generator RG, the reformer 2 has an outer cylinder 21, an inner cylinder 22, a catalyst packed layer 23, a base end cover plate 24, and a terminal end cover plate 25.

The outer cylinder 21 and the inner cylinder 22 are formed in a cylindrical shape with a common axis extending vertically, and although their vertical lengths are roughly the same, the diameter of the outer cylinder 21 is larger than the diameter of the inner cylinder 22. The outer cylinder 21 and the inner cylinder 22 form a reaction vessel 2a with a double cylinder structure in which the inner cylinder 22 is disposed inside the outer cylinder 21. Between the outer cylinder 21 and the inner cylinder 22, i.e., inside the reaction vessel 2a, a catalyst packed layer 23 filled with a catalyst for steam reforming is provided.

The proximal cover plate 24 connects the proximal ends (upper ends) of the outer cylinder 21 and the inner cylinder 22 to close off the upper side of the reaction vessel 2a, and the distal side cover plate 25 connects the proximal ends (upper ends) of the outer cylinder 21 and the inner cylinder 22. The ends (lower ends) of the reaction vessel 2a are connected to each other to close the lower side of the reaction vessel 2a.

The base end cover plate 24 and the distal end cover plate 25 are annular head plates, and the cross-sectional shape of the annular head plate is dish-shaped, regular semi-elliptical, or approximately semi-elliptical. By using an annular head plate as the cover plate of the reaction vessel 2a, radial expansion and contraction due to temperature changes can be absorbed. Therefore, damage or breakage of the reaction vessel 2a due to thermal stress can be more effectively avoided. The cross-sectional shapes of the above head plates are those specified in JIS B 8247 "Head plates for pressure vessels", excluding flat head plates.

In addition, a bellows-structured expansion and contraction absorbing section 21c is formed in the outer cylinder 21 slightly above the intake port 21a. By providing the expansion and contraction absorbing section 21c, expansion and contraction due to temporal temperature changes and positional temperature distribution of the outer cylinder 21 are absorbed. Therefore, damage and breakage of the reaction vessel 2a containing the catalyst due to thermal stress can be avoided, and the reaction vessel 2a can be used for a long period of time. Note that it is preferable to use a commercially available bellows-type expansion pipe joint as the expansion and contraction absorbing section 21c, and the outer cylinder 21 can be manufactured inexpensively by joining this pipe joint to a straight pipe.

In the reformed gas generator RG, the burner 3 has a first gas cylinder 31, a second gas cylinder 32, a flame stabilizer 33, and a heat radiation cylinder Za.

The first gas cylinder 31 and the second gas cylinder 32 are formed in a cylindrical shape with a common axis extending vertically, and the diameter of the second gas cylinder 32 is larger than the diameter of the first gas cylinder 31. The upper part of the first gas cylinder 31 protrudes upward beyond the upper end of the second gas cylinder 32, and the lower part of the first gas cylinder 31 is disposed inside the second gas cylinder 32. The upper end of the first gas cylinder 31 is sealed, and the gap between the first gas cylinder 31 and the second gas cylinder 32 is sealed at the upper end of the second gas cylinder 32.

The second gas cylinder 32 and the heat radiation cylinder Za are formed of one tube, and the lower end of the second gas cylinder 32 is connected to the upper end of the heat radiation cylinder Za. By forming the second gas cylinder 32 and the heat radiating cylinder Za in one tube in this way, operations such as alignment and joining of both members are unnecessary, and the burner 3 can be manufactured at low cost. Further, as shown in FIG. 10, the first burner gas Gx described above flows into the upper part of the first gas cylinder 31, and the aforementioned second burner gas Gy flows into the upper part of the second gas cylinder 32.

The flame stabilizer 33 is connected to the lower end of the first gas cylinder 31 and is formed in a truncated cone shape with its tip expanding downward (downstream of the flow of gas to be burned). The flame stabilizer 33 has multiple rows of through holes 33a spaced apart in the expanding direction. The outer diameter of the flame stabilizer 33 and the inner diameter of the second gas cylinder 32 are formed to be approximately the same diameter, so that the burner 3 can burn the first burner gas Gx and the second burner gas Gy and form a stable flame over the entire radial cross section of the inner diameter of the second gas cylinder 32.

Further, as shown in FIG. 11, the burner 3 is equipped with an electrode pair 40x consisting of a first electrode rod 41 and a second electrode rod 42, and the tip of the electrode pair 40x is disposed inside the flame stabilizer 33. has been done. The first electrode rod 41 is electrically insulated from the first gas cylinder 31, and the second electrode rod 42 is electrically connected to the first gas cylinder 31.

The electrode pair 40x is connected to an ignition/flame detection circuit 40 that performs operation control of gas ignition and flame detection, and can be used for both gas ignition and flame detection. The ignition/flame detection circuit 40 includes a gas ignition section 40a, a current detection section 40b, a first switch 40c1, and a second switch 40c2. At the time of gas ignition, the ignition/flame detection circuit 40 connects the electrode pair 40x to the gas ignition section 40a by closing the first switch 40c1 and opening the second switch 40c2, and transmits a high current from the gas ignition section 40a between the electrodes. ignite the gas by flowing it through the gas to generate a spark.

On the other hand, when detecting a flame, the ignition/flame detection circuit 40 connects the electrode pair 40x to the current detection section 40b by opening the first switch 40c1 and closing the second switch 40c2, and applies a voltage between the electrodes. The current detection unit 40b detects the current to determine the presence or absence of flame. Thereby, it is possible to detect the presence or absence of a flame by utilizing the flame conduction phenomenon when a voltage is applied between the electrodes.

In this way, when gas is ignited, the burner 3 causes the first electrode rod 41 to function as a spark rod and the second electrode rod 42 to function as an earth rod. On the other hand, when flame detection is performed, the burner 3 causes the first electrode rod 41 to function as a flame rod and the second electrode rod 42 to function as an earth rod. Therefore, the burner 3 can perform reliable and safe combustion operation by configuring the gas ignition mechanism and the flame detection mechanism to be switchable using the electrode pair 40x consisting of the first electrode rod 41 and the second electrode rod 42.

The heat radiation tube Za is formed in a cylindrical shape with a common axis with the inner tube 22, and the outer diameter of the heat radiation tube Za is smaller than the inner diameter of the inner tube 22. In addition, the upper end of the heat radiation tube Za is connected to the lower end of the second gas tube 32 inside the inner tube 22, and the lower end of the heat radiation tube Za protrudes downward beyond the lower end of the inner tube 22. The heat radiation tube Za can also be considered as one element of the burner 3.

The heat radiator Za functions as a combustion chamber and a flow path for combustion gas in the burner 3, and its surface serves as a radiator for combustion heat. Since the combustion flame of the burner 3 is located inside the heat radiating tube Za, it is possible to efficiently radiate the thermal energy from this combustion flame from the outer surface of the heat radiating tube Za. In this embodiment, the heat radiator tube Za functions as a combustion chamber tube, so even if combustion heat is continuously applied from the inside to the reaction vessel 2a containing the catalyst, damage or breakage of the heat radiator tube Za due to thermal stress is avoided. can do.

The heat radiation tube Za is inserted into the inner tube 22 so that the surfaces of the heat radiation tube Za and the inner tube 22 are separated in the entire circumferential direction. In this way, a gap is provided between the outer surface of the heat radiation tube Za and the inner surface of the inner tube 22. Therefore, when thermal energy is provided from the inner tube 22 side to the catalyst packed layer 23 for the steam reforming reaction, heat is transferred by radiation from the heat radiation tube Za, and does not involve thermal conduction. This makes it possible to use the reaction vessel 2a containing the catalyst for a long period of time while avoiding damage or breakage due to thermal stress of the reaction vessel 2a.

In the reformer 2, an inlet 21a for mixed gas Gb (mixed gas of raw fuel gas Ga and water vapor) is provided near the lower end of the outer cylinder 21, and an outlet 21b for reformed gas Gc is provided near the upper end of the outer cylinder 21. The mixed gas Gb taken in between the outer cylinder 21 and the inner cylinder 22 from the inlet 21a is reformed as it passes through the catalyst packed layer 23, and is taken out as reformed gas Gc from the outlet 21b. Thus, in this embodiment, the inlet 21a is provided on the side corresponding to the tip side of the heat radiation cylinder Za, and the outlet 21b is provided on the side corresponding to the base end side of the heat radiation cylinder Za.

Here, the thermal energy of the combustion gas Gg is used to absorb heat associated with the steam reforming reaction, so the temperature of the combustion gas Gg decreases from the base end to the tip end of the heat radiation tube Za. Taking this into consideration, in this embodiment, the intake port 21a and the outlet port 21b are arranged as described above, so that the mixed gas Gb flowing in from the intake port 21a is preheated by the reduced temperature combustion gas Gg, and then reformed using the thermal energy of the higher temperature combustion gas Gg.

The generated reformed gas Gc (gas containing hydrogen and carbon monoxide) is continuously discharged from the outlet 21b and used as an anode fuel gas for each cell stack 1. In this manner, in this embodiment, the flows of the mixed gas Gb and the reformed gas Gc and the flow of the combustion gas are opposed to each other, so that an efficient steam reforming reaction can be performed.

However, the arrangement of the intake 21a and the outlet 21b may be reversed from that of this embodiment, with the intake 21a provided on the side corresponding to the base end of the heat radiation tube Za and the outlet 21b provided on the side corresponding to the tip end of the heat radiation tube Za. In this case, the mixed gas Gb flowing in from the intake 21a is instantly preheated by the high-temperature combustion gas Gg, and then reformed using the thermal energy of the combustion gas Gg, which has a slightly lower temperature. In this way, by making the flow of the mixed gas Gb and the reformed gas Gc parallel to the flow of the combustion gas Gg, the preheating effect of the mixed gas Gb is high, and it is possible to design the evaporator 4, which prepares the mixed gas Gb, with reduced heating capacity (heat exchange capacity), which is expected to reduce the cost of the evaporator 4.

<Combustion gas pipe>
Next, the configuration of the combustion gas pipe Zb will be described in more detail. Fig. 12 is a side view of the hot module HM in which the boxes X1, X2, the plate-shaped insulating material 53, and the manifolds Ma to Md are not shown in order to make the arrangement of the combustion gas pipe Zb easier to understand.

As shown in this figure, the combustion gas pipe Zb is composed of a folded pipe path that makes a U-turn at the top so that the straight pipes extending vertically are lined up on the left and right (i.e. parallel), and is arranged behind the reformer 2. The left and right straight pipes that are connected at the top extend from near the bottom end to near the top end of the reformer 2, and are arranged directly opposite each other near the outer cylinder 21 of the reformer 2. As shown by the dashed arrows in Figure 12, the combustion gas Gg flows up the straight pipe on the right side and down the straight pipe on the left side.

As a result, the combustion gas Gg generated when the burner 3 is activated flows through the heat radiation tube Za and the combustion gas pipe Zb in sequence, and can provide combustion heat from both the inside and outside of the reformer 2 at the same time. As a result, the amount of heat absorbed in the catalyst layer increases and the temperature of the combustion gas Gg drops significantly, making it possible to supply the combustion gas Gg with a reduced temperature to the preheating heat exchanger, and the heat exchanger can be made from inexpensive materials (e.g. SUS321, SUS316L, SUS310S, etc.).

In addition, since the amount of heat absorbed in the catalyst layer increases significantly, the efficiency of the steam reforming reaction increases, and the amount of catalyst used can be reduced accordingly, making it possible to downsize the reformer 2. ing. In this embodiment, most of the energy required for the steam reforming reaction in the reformer 2 is provided by combustion heat. Therefore, the reformer 2 can stably generate the reformed gas Gc without depending on the operating temperature of the cell stack 1.

As shown in FIG. 12, the left combustion gas pipe Zb is disposed directly opposite the right side of the left cell stack assembly 61, and the right combustion gas pipe Zb is disposed directly opposite the left side of the right cell stack assembly 61. This allows the fuel cell system 100 to shorten its startup operation time.

In other words, in a reforming fuel cell system that uses steam reforming, steam (superheated steam) may be used to heat the reformer and cell stack during startup operation of the fuel cell system. In this case, the combustion gas generated by the combustion of the burner is used as the heat source for the evaporator, and water is heated inside the evaporator to generate steam. However, when using only steam to heat the evaporator, the startup operation time is generally very long, at more than eight hours. In this embodiment, the combustion gas pipe Zb is disposed near the reformer 2 and cell stack assembly 61, so that the cold reformer 2 and cell stack assembly 61 are indirectly heated by the heat radiation during burner combustion. As a result, the startup operation time can be shortened to, for example, around four hours.

In this embodiment, the reformer 2 is disposed near the cell stack assembly 61, and waste heat from the power generation reaction in the cell stack 1 is also used to supplement the steam reforming reaction in the reformer 2. Therefore, even if the energy loss increases due to deterioration of the power generation cells, the cell stack 1 can be cooled and maintained at an appropriate operating temperature.

In addition, in this embodiment, by making the combustion gas pipe Zb a turn-back pipe, the heat of combustion can be repeatedly applied from the outside of the reformer 2, and the amount of heat absorbed in the catalyst layer is further increased. Therefore, by reducing the amount of catalyst used and making the reformer 2 more compact, the material costs of the hot module HM can be effectively reduced. The turn-back pipe may be laid so that the straight portion of the pipe runs along the axial direction of the reformer 2, or may be laid perpendicular to the axial direction of the reformer 2. In addition, although the turn-back pipe has one turn in this embodiment, the turn-back pipe may have multiple turns.

<Cell stack>
Next, a more detailed description will be given of the configuration of the cell stack 1. Figures 13 and 14 are perspective views of the cell stack 1, and Figure 14 is a plan view of the cell stack 1.

As shown in Figures 13 to 15, the cell stack 1 comprises a stacking section 75 in which a predetermined number of flat-type power generating cells are stacked on the left and right, a first end plate 76a provided at the left end of the stacking section 75, and a second end plate 76b provided at the right end of the stacking section 75. The first end plate 76a and the second end plate 76b are provided as a pair of end plates facing each other on the left and right sides of the stacking section 75, and are approximately rectangular when viewed from the left.

A flanged gas port 72 is disposed near each of the four corners of the first end plate 76a. Specifically, as shown in FIG. 14, a total of four flanged gas ports 72 are provided, consisting of an anode fuel inlet port 72a, a cathode air inlet port 72b, an anode off-gas outlet port 72c, and a cathode off-gas outlet port 72d. Each flanged gas port 72 has a flange portion 72x that extends radially from the entire circumference of the left (outer) edge.

The cell stack 1 is also provided with a support plate 71 that is fixed to the edge of the flange portion 72x of each flanged gas port 72. The support plate 71 has through holes formed therein that correspond to the position and size of each flange portion 72x of each flanged gas port 72, and the outer circumferential surface of each flange portion 72x is in close contact with the inner circumferential surface of each through hole.

A plate-shaped first power terminal 74a and a second power terminal 74b with the top and bottom in the width direction are arranged on the front side of the stacked portion 75 as terminals for outputting the power generated by the power generation cells of the stacked portion 75. The first power terminal 74a and the second power terminal 74b are power terminals with different polarities. The first power terminal 74a protrudes forward from the front side of the stacked portion 75, and the end 74a1 is bent to the left. The second power terminal 74b protrudes forward from a position on the front side of the stacked portion 75 that is lower and to the left of the first power terminal 74a, and the end 74b1 is bent to the right.

In this way, the first power terminal 74a and the second power terminal 74b are arranged substantially parallel to and in the same direction (in the example of this embodiment, in the front ) stands out. The ends 74a1 and 74b1 of each power terminal form a plane facing forward, and are located at the same position in the front-rear direction and the left-right direction.

<Cell stack assembly>
Next, the configuration of the cell stack assembly 61 will be described in more detail. Figures 16 and 17 are perspective views of the left cell stack assembly 61 as viewed from different viewpoints. In this embodiment, the cell stack 1 in the right cell stack assembly 61 is arranged upside down compared to the cell stack 1 in the left cell stack assembly 61. As a result, the cell stack assemblies 61 provided on the left and right sides of the reformer 2 are configured such that the power terminals 74a, 74b are located forward, and the flanged gas port 72 is located inside in the left-right direction.

The cell stack assembly 61 is configured by stacking multiple cell stacks 1 vertically using an open rack 62. This makes it possible to minimize the installation area of the cell stack assembly 61, and therefore the installation area of the hot module HM. Therefore, according to this embodiment, it is possible to construct a fuel cell system 100 that can be easily installed in a narrow space, such as the empty space of an existing facility. In addition, by mounting multiple cell stack assemblies 61 on the hot module HM, it is also easy to increase the capacity of the power generation output of the fuel cell system 100.

The open rack 62 has pillars 64 extending vertically provided at each of the four corners when viewed from above, and a plurality of stage boards 63 are arranged at approximately equal intervals in the vertical direction so as to be fixedly supported by the four pillars 64. has been done. The size of the space sandwiched between the stage boards 63 is set to match the size of the cell stack 1.

The individual cell stacks 1 are placed on the stage board 63 and housed in the open rack 62 with the support plate 71 fixed to the right column 64 by, for example, screws. Therefore, to assemble the cell stack assembly 61, it is only necessary to repeat the operations of placing the cell stack 1 on the stage board 63 and fixing the support plate 71 to the column part 64. Thereby, the cell stack assembly 61 can be easily assembled. Furthermore, the individual cell stacks 1 have their own weight stably supported by the stage board 63, are held at appropriate positions in the vertical direction, and are prevented from falling off during operation.

The above-mentioned open rack 62 is designed to be capable of mounting a specified number of cell stacks 1 (four in this embodiment), but instead of the open rack, an open rack assembled from multiple unit racks corresponding to one cell stack 1 may be used. Figure 18 shows an example of a cell stack 1 mounted on a unit rack 62a that can form such an open rack.

The unit rack 61a has a stage plate 63a having a configuration equivalent to one stage of the stage plate 63 in the open rack 62, and four pillars 64a having a configuration equivalent to one stage of the four pillars 64 in the open rack 62, and it is possible to stack and fix the unit racks 61a vertically. As a result, in the same manner as in the case of the open rack 62, the required number of cell stacks 1 can be accommodated in each unit rack 61a, and by stacking and fixing each of the accommodated unit racks 61a (stack holders), it is possible to obtain something equivalent to the cell stack assembly 61 described above.

The open rack in this case is formed by unit racks 61a divided into each cell stack 1. When the unit rack 61a is used in this manner, the number of cell stacks 1 mounted can be easily adjusted depending on, for example, the power generation output of the hot module HM. Further, since there is no vacant space in the open rack where the cell stack 1 is not mounted, the material cost of the rack can be reduced.

<Manifold branch pipe>
Each flanged gas port 72 in all cell stacks 1 is connected to a branch pipe extending from the corresponding manifold. Specifically, the anode fuel inflow port 72a is connected to a branch pipe extending from the first distribution manifold Ma, the cathode air inflow port 72b is connected to a branch pipe extending from the second distribution manifold Mb, and the anode off-gas outflow port 72c is connected to the branch pipe extending from the first distribution manifold Ma. The cathode off-gas outlet port 72d is connected to a branch pipe extending from the second collection manifold Md. In this embodiment, since there are eight cell stacks 1, eight branch pipes extend from each manifold.

The branch pipes extending from each manifold Ma to Md have a pipe length longer than the shortest distance connecting the corresponding flanged gas port 72 and the manifold, and are configured to include a curved portion. Further, each branch pipe is provided with a flange at its tip, and the flange can be connected to the flange portion 72x of the corresponding flanged gas port 72.

Figure 19 shows an example of the configuration of branch pipes extending from each manifold Ma to Md (collectively referred to as "manifold Mx" for convenience). Each branch pipe BP shown in this figure extends from the manifold Mx and has a flange Fg at its tip.

In the example shown in FIG. 19(A), a state in which two branch pipes BP extend from the manifold Mx to two cell stacks 1 is partially shown, and one branch pipe BP has a curved portion. CV1 is included, and the other branch pipe BP includes a curved portion CV2. Both of these curved portions CV1 and CV2 have a planar (that is, two-dimensional) pipe structure. That is, in the entire region of the curved portion CV1, the cross-sectional center of the branch pipe BP (the cross-sectional center when cut along a plane perpendicular to the extending direction of the branch pipe BP) is the same plane (a plane perpendicular to the axial direction of the manifold Mx). ), and the cross-sectional center of the branch pipe BP is included in the same plane (a plane perpendicular to the axial direction of the manifold Mx) in the entire region of the curved portion CV2.

The example shown in Figure 19 (B) partially illustrates a state in which one branch pipe BP extends from the manifold Mx to one cell stack 1, and this branch pipe BP includes a curved section CV3. This curved section CV3 also has a planar pipe structure. In other words, the center of the cross-sectional view of the branch pipe BP throughout the entire area of the curved section CV3 is included in the same plane (a plane perpendicular to the axial direction of the manifold Mx). In addition, a bellows-type expansion joint Bp1 is provided midway in the branch pipe BP, making it possible to absorb the expansion and contraction of the branch pipe BP.

The example shown in Figure 19 (C) partially illustrates the state in which two branch pipes BP extend from a manifold Mx to two cell stacks 1, with one branch pipe BP including a curved portion CV4 and the other branch pipe BP including a curved portion CV5. Both of these curved portions CV4 and CV5 have a three-dimensional pipe structure. In other words, in both curved portions CV4 and CV5, the cross-sectional center of the branch pipe BP is not contained in the same plane over the entire area.

In the example shown in FIG. 19(D), a state in which two branch pipes BP extend from the manifold Mx to two cell stacks 1 is partially shown, and one branch pipe BP has a curved portion. CV6 is included, and the other branch pipe BP includes a curved portion CV7. Both of these curved portions CV6 and CV7 have a three-dimensional pipe structure. That is, in either of the curved portions CV6 and CV7, the cross-sectional center of the branch pipe BP is not included in the same plane in the entire area.

As shown in the example of Figure 19 (A) or (B), by providing a curved section with a planar pipe structure in the branch pipe BP of the manifold Mx, the expansion and contraction of the pipe that occurs mainly in the horizontal direction of the branch pipe BP (the direction perpendicular to the vertical direction of the hot module HM) can be effectively absorbed. This solves the problem of gas leaks caused by stress acting on the joint with the flanged gas port 72.

On the other hand, as in the example shown in Figure 19 (C) or (D), if a curved section with a three-dimensional pipe structure is provided in the branch pipe BP of the manifold Mx, expansion and contraction of the pipe that occurs in the vertical direction (up and down direction of the hot module HM) as well as the horizontal direction of the branch pipe BP can be effectively absorbed. This solves the problem of gas leaks caused by stress acting on the joint with the flanged gas port 72. The type of pipe structure to be provided in the branch pipe of each manifold Ma to Md can be determined according to, for example, the specifications of the hot module HM.

<Power terminal and its connection form>
Further, in both the left and right cell stack assemblies 61, the respective power terminals 74a and 74b in each cell stack 1 protrude forward, and the ends 74a1 and 74b1 of these power terminals are located at positions in the front-rear direction and the left-right direction. are arranged so that they are the same. Moreover, in the cell stacks 1 in the same cell stack assembly 61, the vertical positional relationship of the first power terminal 74a and the second power terminal 74b is aligned. That is, in the cell stack assembly 61 on the right side, the first power terminal 74a is located above the second power terminal 74b in any cell stack 1, and in the cell stack assembly 61 on the left side, the first power terminal 74a is located above the second power terminal 74b in any cell stack 1. Also, the first power terminal 74a is located below the second power terminal 74b.

The power terminals 74a and 74b of adjacent cell stacks 1 are electrically connected using a main bus bar 78a and a sub bus bar 78b, as shown in FIGS. It is possible to collect the generated power and output it to the outside. Note that each bus bar 78a, 78b is connected and fixed to the end portion 74a1, 74b1 of each power terminal, for example, by screwing or the like.

Here, Figure 20 shows a schematic diagram of the connection of each power terminal 74a, 74b. As shown in this figure, in each cell stack 1 of the cell stack assembly 61 on the right side, the first power terminal 74a is provided above the second power terminal 74b, and in each cell stack 1 of the cell stack assembly 61 on the left side, the first power terminal 74a is provided below the second power terminal 74b.

In the cell stack assembly 61 on the right side, the second power terminal 74b of the topmost cell stack 1 is connected to the first power terminal 74a of the second cell stack 1 from the top, and the second power terminal 74a of the second cell stack 1 from the top is connected. connection between the second power terminal 74b of the cell stack 1 in the third row from the top and the first power terminal 74a of the cell stack 1 in the third row from the top, and the connection between the second power terminal 74b of the cell stack 1 in the third row from the top and the cell stack 1 in the bottom row Each of the connections with the first power terminal 74a is realized by a main bus bar 78a.

In the cell stack assembly 61 on the left side, the first power terminal 74a of the cell stack 1 at the top level and the second power terminal 74b of the cell stack 1 at the second level from the top are connected, and the cell stack 1 at the second level from the top is connected. connection between the first power terminal 74a of the cell stack 1 in the third row from the top and the second power terminal 74b of the cell stack 1 in the third row from the top, and the connection between the first power terminal 74a of the cell stack 1 in the third row from the top and the cell stack 1 in the bottom row The connection with the second power terminal 74b is realized by the main bus bar 78a.

Furthermore, the second power terminal 74b of the lowest cell stack 1 in the cell stack assembly 61 on the right side and the first power terminal 74a of the lowest cell stack 1 in the cell stack assembly 61 on the left side are connected by the sub-bus bar 78b. It has been realized. Further, the first power terminal 74a of the uppermost cell stack 1 in the cell stack assembly 61 on the right side and the second power terminal 74b of the uppermost cell stack 1 in the cell stack assembly 61 on the left side are connected to different terminals. It is connected to power line 79. These power lines 79 are protected by separate power line protection tubes 79a, and extend to the outside of the hot module HM.

The main bus bar 78a is made of a metal plate having an expansion/contraction absorbing portion 78a1 to prevent malfunctions caused by vertical expansion/contraction due to the temperature difference between when the hot module HM is in a cold state and when it is in a power generating state. In this embodiment, the expansion/contraction absorbing portion 78a1 is a U-shaped curved portion when viewed from the left and right as shown in FIG. 8, etc., but it may also be a V-shaped bent portion or the like. By employing a main bus bar 78a having an expansion/contraction absorbing portion 78a1, thermal stress is alleviated, making it possible to realize stable power generating operation and also preventing excessive force from acting on the cell stack 1 of each stage.

The sub-busbar 78b is made of a metal plate having an expansion/contraction absorbing portion 78b1 to prevent malfunctions caused by horizontal expansion/contraction due to the temperature difference between when the hot module HM is in a cold state and when it is in a power generating state. In this embodiment, the expansion/contraction absorbing portion 78b1 is a curved portion that is U-shaped when viewed from the top and bottom as shown in FIG. 5, etc., but it may also be a V-shaped bent portion or the like. By employing the sub-busbar 78b having the expansion/contraction absorbing portion 78b1, thermal stress is alleviated, making it possible to realize stable power generating operation and also preventing excessive force from acting on the uppermost cell stack 1.

<Cooling body>
Next, the configuration of the cooling air line Lk including the cooling pipe Zc will be described in detail. Fig. 21 is a perspective view of a hot module HM showing an example of the installation of the cooling air line Lk. In Fig. 21, the first box X1, the second box X2, and the plate-shaped insulation material 53 are not shown, as in Fig. 5, and further, the parts other than the main parts of the cooling air line Lk are shown lightly, and the inflow and outflow directions of the cooling air Ad are roughly indicated by colored arrows.

As shown in FIG. 21, the cooling pipe Zc and collection pipe Lk1 in the cooling air line Lk are arranged in front of the reformer 2 and the left and right cell stack assemblies 61. More specifically, the cooling pipe Zc extending vertically is arranged near the main bus bar 78a in front of each of the left and right cell stack assemblies 61. The lower ends of these two left and right cooling pipes Zc are connected to each other by a connecting pipe Lkx extending horizontally, and this connecting pipe Lkx is arranged near the sub-bus bar 78b. An extension pipe Lky extending upward extends from approximately the center of the connecting pipe Lkx, and the connecting pipe Lkx and the extension pipe Lky are integrated to form the collection pipe Lk1.

The two cooling pipes Zc and the collecting pipe Lk1 (connecting pipe Lkx, extension pipe Lky) are, for example, placed approximately in the center of a large diameter pipe body bent into a U-shape (or U-shape). It is possible to form a small-diameter tube (a tube whose radial size is smaller than a large-diameter tube) by welding.In this case, each end of the large-diameter tube becomes the cooling pipe Zc, and the other This part becomes the collection tube Lk1. In this way, both end portions of the large-diameter pipe body that are bent back are defined as cooling pipes Zc, and a connecting pipe Lkx, which is a portion between the cooling pipes Zc in the large-diameter pipe body, and a connecting pipe A small diameter tube body (extension tube Lky) arranged to extend from Lkx can be used as collection tube Lk1. The collection pipe Lk1 plays a role of merging and guiding the cooling air Ad that has passed through the two cooling pipes Zc.

Furthermore, the cooling air Ad flowing through the cooling pipe Zc is also used to cool the main bus bar 78a, and the cooling air Ad flowing through the connecting pipe Lkx is also used to cool the sub-bus bar 78b. This reduces the electrical resistance of the main bus bar 78a and the sub-bus bar 78b, suppressing the transmission loss of the generated power.

In the first embodiment, a cooling pipe Zc is installed near the cell stack assembly 61 so as to extend in the stacking direction of the cell stack 1, and by flowing the cooling air Ad in a downward flow, the hot module HM is The cooling is done from the top to the bottom. Note that in order to increase the cooling capacity, cooling pipes may also be installed on the back side (rear side of the cell stack assembly 61).

In this case, one or both of the front and rear cooling pipes may be operated depending on the internal temperature of the hot module HM. As an example, when the internal temperature of the hot module HM is below a predetermined threshold, cooling air Ad may be made to flow only through the front cooling pipe Zc, and when it exceeds the predetermined threshold, cooling air Ad may be made to flow through both the front and rear cooling pipes Zc.

As described above, the hot module HM of this embodiment includes a cell stack 1 and a cooling pipe Zc through which cooling air Ad flows. The cooling pipe Zc is installed near the cell stack 1, and the amount of heat inside the hot module HM is controlled by adjusting the flow rate of the cooling air Ad introduced into the cooling pipe Zc. Therefore, the hot module HM can easily maintain the operating temperature of the cell stack 1 within an appropriate range. The cooling pipe Zc corresponds to one form of the cooling body (a cooling body having a tubular shape) according to the present invention.

Note that the arrangement of the cooling pipes Zc is not limited to that of the first embodiment, and other arrangements may be adopted depending on various purposes. Specific examples of the hot module HM in which the cooling pipes Zc are arranged in a different manner will be described below as a second embodiment and a third embodiment.

2. Second embodiment Next, a second embodiment of the present invention will be described. The second embodiment is basically the same as the first embodiment, except for the configuration of the cooling air line Lk (particularly the arrangement of the cooling pipes Zc). In the following description, the emphasis will be placed on the differences from the first embodiment, and the description of the commonalities with the first embodiment may be omitted.

Figure 22 is a perspective view of the hot module HM according to the second embodiment, and shows the main parts of the cooling air line Lk in color. In Figure 22, as in Figure 21, the first box X1, the second box X2, and the plate-shaped insulation material 53 are not shown, and the parts other than the main parts of the cooling air line Lk are shown in a lighter color, and the inflow and outflow directions of the cooling air Ad are shown roughly with colored arrows.

As shown in FIG. 22, in the second embodiment, the cooling pipes Zc are installed in a spiral shape with the vertical direction as the axial direction so as to entirely surround the plurality of cell stack aggregates 61 when viewed from above. Moreover, the spiral shape extends from the uppermost cell stack 1 to the lowermost cell stack 1 when viewed from the front, back, left, and right directions.

Furthermore, the cooling pipe Zc has corresponding parts extending forward and backward corresponding to the second end plates 76b (end plates) of all the cell stacks 1. Each of the corresponding parts is close to the corresponding second end plate 76b, which enables the cooling pipe Zc to efficiently cool each cell stack 1. Note that in the second embodiment as well, the hot module HM is cooled from the upper layer toward the lower layer by flowing the cooling air Ad in a downward flow.

3. Third Embodiment Next, a third embodiment of the present invention will be described. The third embodiment is basically the same as the first embodiment except for the configuration of the cooling air line Lk (particularly the arrangement configuration of the cooling pipe Zc). In the following description, emphasis will be placed on the explanation of points different from the first embodiment, and explanations of points common to the first embodiment may be omitted.

FIG. 23 is a perspective view of the hot module HM according to the third embodiment, in which the main part of the cooling air line Lk is schematically illustrated in color. Note that in FIG. 23, as in FIG. 21, the first box X1, the second box X2, and the plate-shaped heat insulating material 53 are not shown, and parts other than the main part of the cooling air line Lk are shown in a lighter manner. The direction of inflow and outflow of cooling air Ad is schematically shown with colored arrows.

As shown in FIG. 23, in the third embodiment, the cooling pipes Zc are installed in a spiral shape with the vertical direction as the axial direction so as to entirely surround the plurality of cell stack aggregates 61 when viewed from above. However, in the third embodiment, when viewed from the front, back, left, and right directions, the spiral shape remains around the top cell stack 1, and the second end plate 76b (end plate) of the top cell stack 1 is It is designed to be intensively cooled.

Note that the cooling pipe Zc has respective corresponding portions extending back and forth corresponding to the second end plates 76b of the left and right cell stacks 1 at the top, and each of the corresponding portions is connected to the corresponding second end plate 76b. Close to each other. This allows the cooling pipe Zc to efficiently cool the uppermost cell stack 1.

According to the third embodiment, by intensively cooling the upper layer of the hot module HM, a temperature difference is created inside the hot module HM. This makes it possible to equalize the temperature by promoting convection of air inside the hot module HM, which is confined by the heat insulating material. Furthermore, when the temperature of the upper layer is high, the cell stack 1 located in the upper layer is actively cooled by air convection. This makes it possible to eliminate temperature distribution in the vertical direction of the stacked cell stack 1. Note that each of the cooling pipes Zc in the first to third embodiments may have a structure or a filling therein that promotes turbulent flow of the cooling air Ad. This promotes the turbulent flow of the cooling air Ad, and can be expected to improve the heat absorption effect.

In addition, in the anode of the cell stack 1, the power generation reaction proceeds more upstream where the hydrogen concentration is higher, resulting in a greater amount of heat generation. Therefore, each cooling pipe Zc in the first to third embodiments may be installed near the cell stack 1 or the cell stack assembly 61 so that the flow direction of the cooling air Ad flowing inside the cooling pipe Zc and the flow direction of the anode fuel flowing inside the cell stack 1 are approximately the same direction. This allows lower temperature cooling air Ad to flow toward the side where the amount of heat generated at the anode is greater, which is expected to increase the amount of heat absorbed by the cooling air Ad and improve cooling efficiency.

The cell stack 1 of the first to third embodiments has a configuration (having a stacking portion 75) in which a predetermined number of flat-type power generation cells are stacked between a pair of end plates (first end plate 76a and second end plate 76b), and the first end plate 76a has an anode fuel inlet port 72a, a cathode air inlet port 72b, an anode off-gas outlet port 72c, and a cathode off-gas outlet port 72d. The cooling pipe Zc of the second and third embodiments is installed so that a portion of it runs along the plate surface of the second end plate 76b. This makes it possible to effectively cool the cell stack 1.

In addition, the cooling pipe Zc in the first to third embodiments is provided as a separate component from each manifold including the second distribution manifold Mb, and each branch pipe including the branch pipe connecting the cathode air inlet port 72b and the second distribution manifold Mb. Therefore, even if there is a change in the specifications of each manifold or each branch pipe, the effect on the cooling pipe Zc is minimized, and the inside of the hot module HM can be stably cooled.

4. Fourth Embodiment Next, a fourth embodiment of the present invention will be described. In the following description, emphasis will be placed on the explanation of points different from the first embodiment, and explanations of points common to the first embodiment may be omitted.

Figure 24 is an explanatory diagram showing the configuration of a fuel cell system 200 according to the fourth embodiment. As shown in Figure 24, the fuel cell system 200 includes six front-stage cell stacks 1a, two rear-stage cell stacks 1b, a reformer 2, a burner 3, an evaporator 4, an air preheater 5, an anode off-gas cooler 6, an anode off-gas condenser 7, a condensed water recovery tank 9, a first raw fuel blower 10, a first air blower 11, a water pump 12, a third air blower 17, a reheater 18, and two cooling bodies 110. In the following description, the front-stage cell stacks 1a and rear-stage cell stacks 1b may be collectively referred to as cell stacks 1.

The fuel cell system 200 also includes the following lines (pipes): a mixed gas line Lb, an anode fuel line Lc, a first anode offgas line Lda, a second anode offgas line Ldb, a cathode air line Le, a cathode offgas line Lf, a combustion gas line Lg, a cooling air line Lk, and a reforming water line Li.

The mixed gas line Lb is a pipe line that connects the fuel intake port E2 and the reformer 2, and in this pipe line, a first raw fuel blower 10 and an evaporator 4 are arranged in order from the upstream side. . The first raw fuel blower 10 is a device that boosts the pressure of raw fuel gas (for example, methane-containing gas such as city gas 13A) Ga taken in from the fuel intake port E2, and sends it to the downstream side of the mixed gas line Lb.

The anode fuel line Lc is a pipe line that connects the reformer 2 and the anode of each previous cell stack 1a. The first anode off-gas line Lda is a conduit that connects the anode of each front-stage cell stack 1a and the anode of each rear-stage cell stack 1b. The first anode off-gas line Lda is arranged to pass through the reheater 18, the anode off-gas cooler 6, the anode off-gas condenser 7, the condensed water recovery tank 9, and the reheater 18 in order from the upstream side.

The second anode off-gas line Ldb is a conduit that connects the anode of each subsequent cell stack 1b and the burner 3. The cathode air line Le is a conduit connecting the air intake port E3 and the cathode of each cell stack 1. The cathode air line Le is arranged to pass through the anode off-gas cooler 6 and the air preheater 5 in order from the upstream side.

The cathode offgas line Lf is a pipe that connects the cathode of each cell stack 1 to the burner 3. The combustion gas line Lg is a pipe that connects the burner 3 to the gas exhaust port (combustion gas exhaust port). The combustion gas line Lg is arranged to pass through the air preheater 5 and the evaporator 4, in that order from the upstream side.

The cooling air line Lk is a pipe that connects the air intake E5 and each cooling body 110. The cooling air line Lk has a third air blower 17 disposed midway, and at a predetermined position α on the rear side, it branches off into a first cooling air line Lka and a second cooling air line Lkb. The third air blower 17 is a device that pressurizes the cooling air Ad taken in from the air intake E5 and sends it downstream of the cooling air line Lk.

The first cooling air line Lka is connected to the inlet side of one of the two cooling bodies 110 (cooling air introduction pipe 115 described later), and the second cooling air line Lkb is connected to the other of the two cooling bodies 110. It is connected to the entrance side. Pipe lines extending from the outlet side of each cooling body 110 (cooling air outlet pipe 116 to be described later) join together at a predetermined position β and are connected to an air outlet.

The reformed water line Li is a pipe line that connects the condensed water recovery tank 9 and a predetermined position of the mixed gas line Lb (a position between the first raw fuel blower 10 and the evaporator 4). A water pump 12 is installed. The water pump 12 is a device that sends water stored in the condensed water recovery tank 9 to the downstream side of the reformed water line Li as reformed water Wa.

Next, an overview of the operation of the fuel cell system 200 will be described with reference to FIG. 24. The raw fuel gas Ga supplied into the mixed gas line Lb from the fuel intake port E2 is sent to the rear stage side by the action of the first raw fuel blower 10. In parallel with the supply of the raw fuel gas Ga, the reformed water Wa supplied from the condensed water recovery tank 9 into the reformed water line Li has its water volume adjusted by the water pump 12 and flows into the mixed gas line Lb.

The reforming water Wa flows into the evaporator 4 together with the raw fuel gas Ga in the mixed gas line Lb, where it is heated by heat exchange to become water vapor (superheated steam). The water vapor mixes with the heated raw fuel gas Ga and flows into the reformer 2 as mixed gas Gb.

The reformer 2 reforms raw fuel gas Ga using water vapor in mixed gas Gb, generates reformed gas Gc, and sends the reformed gas Gc to the subsequent stage side. The reformed gas Gc sent out from the reformer 2 is distributed to the anodes of each previous cell stack 1a through the anode fuel line Lc.

Meanwhile, in parallel with the supply of the raw fuel gas Ga described above, air Aa is supplied from the air intake E3 into the cathode air line Le. The air Aa in the cathode air line Le is sent to the rear stage by the action of the first air blower 11. This air Aa is heated by heat exchange in the anode off-gas cooler 6, and is further heated by heat exchange in the air preheater 5, after which it is distributed to the cathodes of each cell stack 1.

The front-stage cell stack 1a generates electricity using the reformed gas Gc that flows into the anode and the air Aa that flows into the cathode, and discharges the first anode offgas Gd1 from the anode to the first anode offgas line Lda and the cathode offgas Ge from the cathode to the cathode offgas line Lf. The first anode offgas Gd1 contains fuel components that have not reacted at the anode, and the cathode offgas Ge contains oxygen that has not reacted at the cathode.

The first anode offgas Gd1 discharged to the first anode offgas line Lda is cooled by heat exchange in the anode offgas cooler 6, and then flows into the anode offgas condenser 7. In the anode off-gas condenser 7, the first anode off-gas Gd1 is cooled to below the dew point temperature, and the water vapor contained in the first anode off-gas Gd1 is condensed.

The first anode off-gas Gd1 that has passed through the anode off-gas condenser 7 is separated into water and steam, and the condensed water is collected in the condensed water recovery tank 9. The condensed water collected in the condensed water recovery tank 9 is reused as reformed water Wa. The first anode off-gas Gd1 after separation is heated in the reheater 18 and then sent to the anode of each downstream cell stack 1b.

The rear-stage cell stack 1b generates electricity using the first anode offgas Gd1 that flows into the anode and the air Aa that flows into the cathode, and discharges the second anode offgas Gd2 from the anode to the second anode offgas line Ldb and the cathode offgas Ge from the cathode to the cathode offgas line Lf. The second anode offgas Gd2 contains fuel components that have not reacted at the anode, and the cathode offgas Ge contains oxygen that has not reacted at the cathode.

The burner 3 receives the second anode offgas Gd2 and the cathode offgas Ge, and burns them to generate heat. Combustion gas Gg generated by combustion in burner 3 is sent to combustion gas line Lg, passes through air preheater 5 and evaporator 4 in this order, and is discharged from the gas outlet to the outside of the hot module.

Also, part of the cooling air Ad supplied from the air intake port E5 to the cooling air line Lk flows into one cooling body 110 via the first cooling air line Lka, and the rest flows into the second cooling air line Lk. It flows into the other cooling body 110 via the air line Lkb. The cooling air Ad flowing into these cooling bodies 110 is used for cooling the inside of the hot module while flowing through the cooling bodies 110, and then is discharged to the outside of the hot module HM from the air outlet.

Next, the configuration of the cooling body 110 will be described. Figure 25 shows a perspective view of the cooling body 110, and Figure 26 shows a cross-sectional view of the cooling body 110 (a cross-sectional view when the cooling body 110 is cut along a plane that divides the cooling body 110 in the width direction). For ease of explanation, the length, width, and height directions of the cooling body 110 are as shown in Figure 25. Furthermore, the two cooling bodies 110 provided in the fuel cell system 200 have the same configuration and function.

The cooling body 110 shown in these figures has an offset fin 117 enclosed inside a box-shaped body formed by brazing together the following components: a first heat absorbing plate 111, a second heat absorbing plate 112, two first side bars 113, two second side bars 114, a cooling air inlet pipe 115, and a cooling air outlet pipe 116. As an example of the material for these components, ferritic stainless steel containing 2% or more Al (for example, high-temperature oxidation-resistant stainless steel such as NCA-1) can be used.

Explaining in more detail, the cooling body 110 has a roughly rectangular parallelepiped structure with an interior cavity formed by a roughly plate-shaped first heat absorption plate 111 with an outer surface facing one side in the height direction, a roughly plate-shaped second heat absorption plate 112 with an outer surface facing the other side in the height direction, two roughly plate-shaped first side bars 113 with outer surfaces facing both sides in the width direction, and two roughly plate-shaped second side bars 114 with outer surfaces facing both sides in the length direction, and the offset fins 117 are arranged in this cavity.

The thickness of each heat absorbing plate 111, 112 is preferably about 1 to 2 mm, and the height dimension of each side bar 113, 114 is preferably about 8 to 12 mm. The width dimension of the second side bar 114 is preferably about 2 to 8 times the height dimension of each side bar 113, 114. The length dimension of the first side bar 113 is set taking into consideration the number and arrangement of the cell stacks 1, which are the heat source. In this embodiment, the length dimension of the cooling body 110 is sufficiently larger than its width dimension.

An end of a cylindrical cooling air introduction pipe 115 is fixed to the outer surface of the first heat absorption plate 111 near one end in the length direction, and a cylindrical cooling air guide pipe 115 is fixed near the other end in the length direction. The end of tube 116 is fixed. A through hole is provided in the first heat absorption plate 111 at a location corresponding to the inside of these pipes 115, 116, and the inside of the cooling air introduction pipe 115 and the cooling air outlet pipe 116 are inside the above-mentioned structure. It communicates with

The cooling air Ad flowing through the first cooling air line Lka and the second cooling air line Lkb flows into the inside of the cooling body 110 from the cooling air introduction pipe 115 and passes through the inside where the offset fins 117 are arranged. After flowing in the length direction, the air flows out from the cooling air outlet pipe 116 to the outside of the cooling body 110 . At this time, the cooling air Ad flows while removing heat from the cooling body 110, thereby cooling the cooling body 110.

Figure 27 shows a schematic perspective view of an offset fin 117 arranged inside the cooling body 110. The thick arrows in Figure 27 indicate the general flow direction of the cooling air Ad. The offset fin 117 shown in this figure has four rows of fin members 117a-117d extending in the length direction, arranged in the width direction. Each of the fin members 117a-117d is formed by bending a strip-shaped plate material so that it extends in the length direction while meandering at a constant interval in the height direction. As is well known, offset fins are manufactured by sheet metal processing, and are typically manufactured through three steps consisting of a first bending process, a cutting process, and a second bending process.

The fin members 117a to 117d have the same basic shape and size, but are arranged so that the meandering positions of adjacent fin members are shifted in the length direction. In the example shown in FIG. 27, there is a positional shift in the length direction between the fin members 117a and 117c and the fin members 117b and 117d, which corresponds to approximately 1/4 of one cycle of meandering. .

By arranging the offset fins 117 in this manner, the turbulence of the cooling air Ad flowing inside the cooling body 110 is promoted, and the heat absorption efficiency of the cooling body 110 is improved. In this embodiment, the shape and arrangement of the offset fins 117 are designed so that the air flow hits the raised surfaces of the fins to make the flow of the cooling air Ad meander in the width and height directions.

Instead of sealing the offset fins 117 inside the cooling body 110, Raschig rings, balls, etc. may be filled inside the cooling body 110 as a filler that promotes turbulence of the cooling air Ad. For example, stainless steel or ceramics may be used as these fillers. Also, if the width of the cooling body 110 is small and it is difficult to seal offset fins, Raschig rings, balls, etc., stainless steel wool (fibrous metal) may be filled inside the cooling body 110 as a filler that promotes turbulence of the cooling air Ad.

Note that the fuel cell system 200 according to this embodiment also has a hot module, and the hot module is divided into a first region and a second region, each of which is surrounded by a heat insulating material, as in the first embodiment. . In the first area, a cell stack 1, a reformer 2, a burner 3, and a cooling body 110 are installed, and in the second area, an evaporator 4, an air preheater 5, an anode off-gas cooler 6, and A reheater 18 is installed.

Note that it is desirable that the reformer 2 and the burner 3 be thermally integrated so that the combustion heat of the burner 3 can be used for the reforming reaction (endothermic). Furthermore, an anode off-gas condenser 7 (air-cooled radiator), a condensed water recovery tank 9, a water pump 12, and various blowers 10, 11, and 17 are installed outside the hot module (outside the heat insulation area). Other basic configurations of the hot module according to the present embodiment can be the same as or based on the hot module HM according to the first embodiment, except for the matters described below.

Next, an example of the arrangement of the cooling body 110 and the like in the hot module of this embodiment will be described. FIG. 28(a) is a plan view showing an example of a configuration in a hot module when the cell stack 1 is integrated in the horizontal direction, and FIG. 28(b) is a side view showing the same configuration in the hot module.

In the example shown in FIG. 28, the insulation material 120 is arranged to surround the first region inside the hot module, and the reformer 2 is arranged in the central region in the front-to-rear direction inside the insulation material 120 (insulated region) so as to extend at least left and right, with the burner 3 arranged to the right of it. Four flat cell stacks 1 are arranged side by side on both the front and rear sides of the reformer 2 in the insulated region.

Each cell stack 1 has a configuration in which a predetermined number of flat power generation cells are stacked between a pair of end plates (a first end plate 76a and a second end plate 76b), and one of the end plates is a first Like the first end plate 76a of the first embodiment, the end plate 76a is provided with an anode fuel inflow port, a cathode air inflow port, an anode off-gas outflow port, and a cathode off-gas outflow port. In each cell stack 1, the first end plate 76a corresponds to an end plate on which these gas ports are formed, and the second end plate 76b corresponds to an end plate on which these gas ports are not formed. corresponds to Each cell stack 1 is arranged so that the first end plate 76a faces upward.

The two cooling bodies 110 are both arranged so that their length directions coincide with the left-right direction. One of the two cooling bodies 110 is arranged so as to cover the upper sides of all four cell stacks 1 arranged in front of the reformer 2, and the lower surface of the second heat absorption plate 112 is parallel to the upper surfaces of the first end plates 76a of these cell stacks 1, and the lower surface and the upper surface are close to each other.

The other of the two cooling bodies 110 is arranged so as to cover the upper sides of all four cell stacks 1 arranged at the rear side of the reformer 2, and the lower surface of the second heat absorption plate 112 covers these cell stacks. It is parallel to the upper surface of the first end plate 76a of No. 1, and the lower surface and the upper surface are close to each other. Note that the upper region SP of each cooling body 110 is a region where both or one of a gas distribution manifold and a gas collection manifold is arranged. Moreover, in the example shown in FIG. 28, the cooling body 110 is installed along the plate surface of the first end plate 76a of each cell stack 1, so that each cell stack 1 can be effectively cooled.

Inside the hot module, as the operating temperature of the cell stack 1 (heat radiation source) increases, the temperature increases toward the upper layer of the heat insulation area due to internal air convection. In this regard, according to the arrangement example shown in FIG. 28, the cooling body 110 is arranged above the cell stack 1, and it is possible to effectively cool the upper layer to the middle layer in the heat insulation region.

Note that the cooling body 110 shown in FIG. 28 is arranged not only to cover the upper side of all four cell stacks 1 as described above, but also to cover the upper side of only the front cell stack 1a or only the rear cell stack 1b. It can also be placed to cover the

Further, FIG. 29(a) is a plan view showing an example of the configuration inside the hot module when cell stacks 1 are integrated in the vertical direction, and FIG. 29(b) is a side view showing the example of the configuration inside the hot module. It is a diagram.

In the example shown in FIG. 29, the insulation material 120 is arranged to surround the first region inside the hot module, and the reformer 2 is arranged in the left-right central region inside the insulation material 120 (insulated region) so as to extend at least vertically, with the burner 3 arranged above it. Four flat cell stacks 1 are arranged vertically in each of the regions on either side of the reformer 2 in the insulated region. Each cell stack 1 is arranged so that the first end plate 76a faces inward in the left-right direction.

The two cooling bodies 110 are both arranged with their length directions aligned vertically so that the cooling air inlet pipe 115 is located above the cooling air outlet pipe 116. This causes the cooling air Ad inside the cooling body 110 to flow downward. One of the two cooling bodies 110 is arranged to cover the left side of all four cell stacks 1 arranged on the left side of the reformer 2, and the right surface of the second heat absorption plate 112 is close to and parallel to the left surfaces of the second end plates 76b of these cell stacks 1.

The other of the two cooling bodies 110 is arranged to cover the right side of all four cell stacks 1 arranged on the right side of the reformer 2, and the left surface of the second heat absorption plate 112 is close to and parallel to the right surfaces of the second end plates 76b of these cell stacks 1. Note that the areas SP on both the front and rear sides of the insulating area are areas where both or either of the gas distribution manifold and collection manifold are arranged.

Inside the hot module, the higher the operating temperature of the cell stack 1 (heat dissipation source), the higher the temperature becomes toward the upper part of the thermal insulation area due to the convection of the internal air. In this regard, according to the arrangement example shown in FIG. 29, it is possible to effectively cool the upper to middle parts of the thermal insulation area by flowing the cooling air Ad from top to bottom inside the cooling body 110. Furthermore, when the temperature of the upper part is high, the cell stack 1 located in the upper part is actively cooled by the air convection. This makes it possible to eliminate the temperature distribution in the vertical direction of the stacked cell stacks 1. In particular, in the example shown in FIG. 29, the cooling body 110 is installed along the plate surface of the second end plate 76b of each cell stack 1, and each cell stack 1 can be effectively cooled.

In addition, the cooling body 110 shown in FIG. 29 can be positioned to cover the right side of all four cell stacks 1 as described above, or can be positioned to cover the right side of only the front-stage cell stack 1a or only the rear-stage cell stack 1b.

Furthermore, in order to further improve the cooling efficiency of the cooling body 110, the flow direction of the cooling air Ad flowing inside the cooling body 110 and the flow direction of the anode fuel flowing inside the cell stack 1 are approximately the same direction. It is desirable to do so. Therefore, the cooling body 110 is arranged in each cell stack so that the flow direction of the cooling air Ad flowing inside the cooling body 110 and the flow direction of the anode fuel flowing inside each cell stack 1 are approximately the same direction. It is installed near 1. Note that "substantially the same direction" here means that the reference flow direction along the straight line connecting the inlet reference point and outlet reference point of one fluid and the reference flow direction of the other fluid are within 45 degrees. This is the case when .

Figure 30 shows three typical examples in which the flow direction of the cooling air Ad and the flow direction of the anode fuel are substantially the same. In Figure 30, the dashed arrow indicates the flow direction of the cooling air Ad flowing inside the cooling body 110, the solid arrow indicates the flow direction of the anode fuel flowing inside the cell stack 1, and the dashed arrow indicates the flow direction of the cathode air flowing inside the cell stack 1.

FIG. 30(a) shows an example of a case where a parallel flow (coflow) type cell stack 1 is applied. In this example, the flow direction of the cooling air Ad is to the left, the flow direction of the anode fuel is diagonally forward to the left (the angle with the left is within 45 degrees), and the flow direction of the cathode air is It is diagonally to the left rear.

Figure 30 (b) shows an example of the application of a counterflow type cell stack 1. In this example, the flow direction of the cooling air Ad is to the left, while the flow direction of the anode fuel is diagonally forward left (within a 45° angle with the left), and the flow direction of the cathode air is diagonally forward right.

Figure 30 (c) shows an example of a cross-flow type cell stack 1. In this example, the flow direction of the cooling air Ad is to the left, while the flow direction of the anode fuel is also to the left, like the cooling air Ad, and the flow direction of the cathode air is backward.

In the anode fuel, the higher the hydrogen concentration is on the upstream side, the more the power generation reaction progresses, so the calorific value increases. Therefore, by making the flow direction of the cooling air Ad and the flow direction of the anode fuel substantially the same as in each example shown in FIG. As a result, the amount of heat absorbed can be increased and the cooling efficiency by the cooling body 110 can be further improved.

Furthermore, in the fuel cell system 200, the amount of heat (temperature) inside the hot module is controlled by adjusting the flow rate of the cooling air Ad introduced into the cooling body 110. As an example, the fuel cell system 200 drives the third air blower 17 when the temperature inside the hot module (for example, the maximum surface temperature of the end plate of each cell stack 1) exceeds the upper limit temperature, and controls the rotation speed of the third air blower 17 so that the temperature inside the hot module becomes a target temperature (a temperature that is a predetermined temperature lower than the upper limit temperature). Furthermore, the fuel cell system 200 stops the third air blower 17 when the rotation speed is below the lower limit value for a predetermined period of time. Note that the flow rate of the cooling air Ad introduced into the cooling body 110 increases as the rotation speed of the third air blower 17 increases.

5. Fifth embodiment Next, a fifth embodiment of the present invention will be described. The fifth embodiment is basically the same as the fourth embodiment, except for the configuration of the cooling body. In the following description, the emphasis will be placed on the differences from the fourth embodiment, and the description of the commonalities with the fourth embodiment may be omitted.

FIG. 31 shows a perspective view of a cooling body 110a according to the fifth embodiment. For convenience of explanation, the length direction, width direction, and height direction of the cooling body 110a are as shown in FIG. Lower side. In the fuel cell system 200 of this embodiment, two cooling bodies 110a are provided instead of the two cooling bodies 110 of the fourth embodiment, and the configurations and functions of the two cooling bodies 110a are equivalent.

As shown in this figure, the cooling body 110a is formed by brazing together the first heat absorption plate 111, the second heat absorption plate 112, the cooling air inlet pipe 115, and the cooling air outlet pipe 116. As an example of the material for these members, ferritic stainless steel containing 2% or more Al (for example, high-temperature oxidation-resistant stainless steel such as NCA-1) can be used.

Furthermore, Fig. 32 shows a schematic diagram of the first heat absorbing plate 111 as viewed from above, and Fig. 33 shows a schematic diagram of the second heat absorbing plate 112 as viewed from above. Note that in Fig. 32, the position of each convex portion 111b (herringbone pattern) is indicated by a solid line, and in Fig. 33, the position of each convex portion 112b (herringbone pattern) is indicated by a dotted line.

The first heat absorption plate 111 has a plate portion 111a with a rectangular outer edge on which multiple protrusions 111b are formed, and a flange portion 111c formed by press working so as to extend downward from the entire outer edge of the plate portion 111a. The multiple protrusions 111b are formed by press working the plate portion 111a so as to protrude downward, and are arranged so as to form a herringbone pattern when viewed from above (multiple "L" shapes lined up at equal intervals in the length direction). In addition, the amount of downward extension of the flange portion 111c (the height of the flange portion 111c) and the amount of downward protrusion of each protrusion 111b are the same, and are preferably about 4 to 6 mm, for example.

The second heat absorption plate 112 includes a plate portion 112a having a rectangular outer edge and a plurality of convex portions 112b, and a flange portion 112c formed by press working so as to extend downward from the entire outer edge of the plate portion 112a. . The plurality of convex portions 112b are formed by pressing the plate portion 111a so as to protrude upward, and are provided in a herringbone pattern when viewed from below. Further, the amount of upward extension of the flange portion 112c (height of the flange portion 112c) and the amount of upward protrusion of each convex portion 112b are preferably the same, and are preferably about 4 to 6 mm, for example.

The first heat absorption plate 111 and the second heat absorption plate 112 are integrated by joining the lower surface of the flange portion 111c and the upper surface of the flange portion 112c by brazing. In addition, in this integrated state, each convex portion 111b on the first heat absorption plate 111 side and each convex portion 112b on the second heat absorption plate 112 side are in point contact at a position where they overlap when viewed from above.

In this integrated structure, the size in the length direction is sufficiently larger than the size in the width direction, and the size in the height direction is smaller than the size in the width direction. An end of a cylindrical cooling air introduction pipe 115 is fixed to the outer surface of the first heat absorption plate 111 near one end in the length direction, and a cylindrical cooling air guide pipe 115 is fixed near the other end in the length direction. The end of tube 116 is fixed.
Through holes 111d and 111e are provided in the first heat absorption plate 111 at locations corresponding to the insides of these tubes 115 and 116 (see FIG. 32), and cooling air inlet tubes 115 and cooling air outlet tubes 116 are provided. The inside communicates with the inside of a cooling body 110a formed between the first heat absorption plate 111 and the second heat absorption plate 112.

FIG. 34 schematically shows an integrated structure of the first heat absorption plate 111 and the second heat absorption plate 112 when viewed from above. In addition, in FIG. 34, the position of each convex part 112b on the second heat absorbing plate 112 side is shown by a dotted line in order to make it easy to understand the positional relationship of the convex parts of each heat absorbing plate. As shown in this figure, the herringbone pattern on the second heat-absorbing plate 112 is the same as the herringbone pattern on the first heat-absorbing plate 111 inverted in the length direction. Furthermore, each convex portion 111b on the side of the first heat absorption plate 111 is located at five positions in total (the center position when viewed from above, two positions at both ends, and two positions intermediate between the center position and both end positions). ), it overlaps with the convex portion 112b on the second heat absorption plate 112 side when viewed from above and is in point contact.

According to the cooling body 110a of this embodiment, by forming the convex parts 111b, 112b on each of the heat absorbing plates 111, 112, the heat absorbing area of the surface of each of the heat absorbing plates 111, 112 is increased, and the turbulence promotion effect inside the cooling body 110a is also enhanced, so that the cooling effect can be improved. The cooling body 110 according to the fourth embodiment and the cooling body 110a according to the fifth embodiment correspond to one form of the cooling body (a cooling body having a box-like shape) according to the present invention.

6. Sixth embodiment Next, a sixth embodiment of the present invention will be described. The sixth embodiment differs from the fourth embodiment mainly in that the cooling air flowing out from the cooling body is used as cathode air, and in points related to this. In the following description, the emphasis will be placed on the points that differ from the fourth embodiment, and the points that are common to the fourth embodiment may be omitted.

FIG. 35 is an explanatory diagram showing the configuration of a fuel cell system 200a according to the sixth embodiment. As shown in FIG. 35, in the fuel cell system 200a, the pipes extending from the outlet side of each cooling body 110 are unified at a predetermined position β and extend as a cathode air line Le. The cathode air line Le passes through the air preheater 5 and is connected to the cathode of each cell stack 1. Note that in the sixth embodiment, since it is not necessary to supply air Aa to the cathode of each cell stack 1, the air intake port E3, the first air blower 11, and the anode off-gas cooler installed in the fourth embodiment are 6 is omitted.

In the fuel cell system 200a, the cooling air Ad supplied to each cooling body 110 via the cooling air line Lk passes through each cooling body 110 and then reaches the cathode of each cell stack 1 via the cathode air line Le. It is supplied and used as cathode air. Thereby, the cooling body 110 of the sixth embodiment can play the role of both cooling the inside of the hot module and preheating the cathode air.

The third air blower 17 is set to adjust its rotation speed according to the required flow rate of the cathode air. For this reason, as shown by the dashed lines in FIG. 35, it is preferable to provide a bypass path BY for each cooling body 110 so that the flow rate of the cooling air Ad flowing through each cooling body 110 can be adjusted. The bypass path BY is installed to connect the pipe near the inlet and the pipe near the outlet of the cooling body 110.

When a bypass path BY is provided, the flow rate of the cooling air Ad passing through the bypass path BY (bypass flow rate) can be reduced and the supply flow rate of the cooling air Ad to the cooling body 110 can be increased as the temperature inside the hot module increases. Specifically, for example, the bypass flow rate can be adjusted so that the temperature inside the hot module reaches a predetermined target temperature (a temperature that is a predetermined temperature lower than the upper limit temperature).

Although the embodiments of the present invention have been described above, the configuration of the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the invention. That is, the above embodiments are illustrative in all respects, and should not be considered restrictive. It is understood that the technical scope of the present invention is indicated by the claims rather than the description of the above embodiments, and includes all changes that fall within the meaning and range equivalent to the claims. Should.

The present invention can be used in fuel cell systems.

LIST OF SYMBOLS 1 Cell stack 2 Reformer 2a Reaction vessel 3 Burner 4 Evaporator 5 Air preheater 6 Anode off-gas cooler 7 Anode off-gas condenser 8 CO oxidizer 9 Condensed water recovery tank 10 First raw fuel blower 11 First air blower 12 Water pump 13 Second raw fuel blower 14 Second air blower 15 Power conditioner 16 System controller 17 Third air blower 51 First support 52 Second support 53 Plate-shaped insulation material 61 Cell stack assembly 62 Open rack 63 Stage board 64 Column section 71 Support plate 72 Flanged gas port 72a Anode fuel inlet port 72b Cathode air inlet port 72c Anode off-gas outlet port 72d Cathode off-gas outlet port 74a First power terminal 74b Second power terminal 75 Stack section 76a First end plate 76b Second end plate 78a Main bus bar 78a1 Expansion absorbing section 78b Sub bus bar 78b1 Expansion absorbing section 79 Power line 79a Power line protection tube 100, 200, 200a Fuel cell system 110, 110a Cooling body 111 First heat absorption plate 111a Plate portion 111b Convex portion 111c Flange portion 111d, 111e Through hole 112 Second heat absorption plate 112a Plate portion 112b Convex portion 112c Flange portion 113 First side bar 114 Second side bar 115 Cooling air inlet pipe 116 Cooling air outlet pipe 120 Thermal insulation material Aa to Ac Air Ad Cooling air B1 First bellows type expansion joint B2 Second bellows type expansion joint B3 Third bellows type expansion joint B4 Fourth bellows type expansion joint D1 Gas exhaust port E1, E2 Fuel inlet E3, E4, E5 Air inlet Ga Raw fuel gas Gb Mixed gas Gc Reformed gas Gd Anode offgas Ge Cathode offgas Gf Raw fuel gas Gg Combustion gas La Raw fuel line Lb Mixed gas line Lc Anode fuel line Ld Anode offgas line Le Cathode air line Lf Cathode offgas line Lg Combustion gas line Lh Burner cooling air line Li Stack cooling air line Lj Reformed water line Lk Cooling air line Lka First cooling air line Lkb Second cooling air line Ma First distribution manifold Mb Second distribution manifold Mc First collection manifold Md Second collection manifold RG Reformed gas generator Wa: Reformed water X1: First box X1a: First base X2: Second box X2a: Second base Za: Heat radiation tube Zb: Combustion gas pipe Zc: Cooling pipe

Claims (8)

A fuel cell stack;
a cooling body through which cooling air flows,
A hot module of a fuel cell system, characterized in that the cooling body is installed near the cell stack, and the amount of heat inside the hot module is controlled by adjusting the flow rate of cooling air introduced into the cooling body. A plurality of the fuel cell stacks are integrated to form a cell stack assembly,
The hot module according to claim 1, wherein the cooling body is installed near the cell stack assembly. The cooling body is arranged in the cell stack or the cells so that the flow direction of the cooling air flowing through the cooling body and the flow direction of the anode fuel flowing inside the cell stack are substantially the same direction. The hot module according to claim 2, wherein the hot module is installed near the stack assembly. 4. The hot module according to claim 1, wherein the cooling body has a box-like or tubular shape. 4. The hot module according to claim 1, wherein the cooling body has a structure or a filling therein for promoting turbulent flow of cooling air. The cell stack has a structure in which a predetermined number of flat power generation cells are stacked between a pair of end plates, and at least one of the end plates has an anode fuel inflow port, a cathode air inflow port, an anode off-gas outflow port, and a cathode. Has an off-gas outflow port,
4. The hot module according to claim 1, wherein the cooling body is installed along a plate surface of the end plate. A manifold that serves as a cathode air inlet pipe;
a branch pipe connecting the cathode air inlet port and the manifold;
7. The hot module of claim 6, wherein the cooling body is a separate component from the manifold and the branch pipes. 4. The hot module according to claim 1, wherein at least a part of the cooling air after flowing through the cooling body is supplied to the cell stack as cathode air.