JP2023134289A - Evaporator of fuel cell system - Google Patents

Abstract

To provide a vertically placed evaporator which is mounted on a fuel cell system and has a compact form in which a height of a plate assembly is reduced.SOLUTION: An evaporator includes: a plate assembly 80 in which multiple heat transfer plates 81 are laminated; meandering passage plates 85 incorporating into low temperature fluid passages formed on one heat transfer surface side of the heat transfer plates 81; and heat transfer fins 88 incorporating into high temperature fluid passages formed on the other heat transfer surface side of the heat transfer plates 81. The plate assembly 80 has: a first header part 83a which distributes water to the low temperature fluid passages; a second header part 83b which collects steam from the low temperature fluid passages; a third header part 83c which distributes a heat source gas to the high temperature fluid passages; and a fourth header part 83d which collects the heat source gas from the high temperature fluid passages. The first header part 83a is formed at an upper part of the plate assembly 80, and the second header part 83b is formed at a lower part of the plate assembly 80.SELECTED DRAWING: Figure 23

Description

The present invention relates to an evaporator for a fuel cell system.

Conventionally, 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 (SOFC) have a high power generation efficiency of 50% or more, and are therefore used for power generation in a wide range of output ranges 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 reformed fuel cell systems, reformed gas is mainly generated using an endothermic external reformer using a steam reforming catalyst, and the reformer and the cell stack are the core of power generation. Auxiliary equipment such as a combustor is packaged to form a thermally self-sustaining hot module.

In order to carry out the steam reforming reaction, it is necessary to supply raw fuel and steam to the reformer. Therefore, as disclosed in Cited Document 1, the auxiliary equipment constituting the hot module includes an evaporator (vaporizer) for generating water vapor in the gas phase from water in the liquid phase. As an evaporator designed to be incorporated into a hot module, a configuration in which improvements are added to a plate heat exchanger is known, as disclosed in Cited Documents 2 and 3.

US Application Publication No. 2008/0311445 Japanese Patent Application Publication No. 2004-53101 Special Publication No. 2007-506060

The evaporator of Patent Document 2 is a vertical evaporator based on a plate-fin heat exchanger, and has heat transfer fins (corrugated fins) in each of the low-temperature side flow path group and the high-temperature side flow path group. Built-in. Fuel gas such as natural gas flows through the low temperature side flow path group, and water is sprayed from the injection tube to the heat transfer fins. A heating gas for evaporating the sprayed water flows through the high temperature side flow path group. This evaporator is configured as an auxiliary device to obtain a mixed gas of fuel gas and water vapor. In the case of a vertically installed evaporator, water evaporation can be promoted by flowing water in a liquid film along the heat transfer fins between the plates, but considering the variation in water distribution in the width direction of the plates, it is possible to accelerate water evaporation to some extent. This requires a plate height of

The evaporator of Patent Document 3 is a horizontal type evaporator based on a plate heat exchanger of the all-circumferential joint type such as brazing, and each of the low-temperature side flow passage groups has heat transfer fins ( It is divided into a vaporization region with built-in offset fins and a downstream superheating region without heat transfer fins. On the other hand, in each of the high-temperature side flow passage groups, an oblique flow passage is formed by overlapping two turbulence promoting plates having elongated slots arranged at a specific angle. High-temperature exhaust gas for evaporating water flows through the high-temperature side flow path group. A water/methanol mixture is supplied to the low temperature side flow path group, and a mixed gas of fuel gas and water vapor is obtained by vaporizing the mixture. In the case of a horizontally placed evaporator, it is difficult to form a liquid film, and a certain plate length is required to ensure a vaporization region that involves preheating and boiling of the liquid phase, making it easy to increase the size of the evaporator.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a compact evaporator that is a vertically installed evaporator that is installed in a fuel cell system and whose plate assembly height is suppressed. purpose.

The evaporator according to the present invention is an evaporator for generating water vapor that is installed in a fuel cell system, and has front and back heat transfer surfaces that are substantially parallel to the vertical direction between a pair of opposing end plates. a plate assembly in which a plurality of heat transfer plates are stacked and the end plate and the heat transfer plate are joined and integrated; and a low temperature fluid flow path formed on one of the heat transfer surfaces of the heat transfer plates. and a heat transfer fin incorporated in each of the high temperature fluid flow paths formed on the other heat transfer surface side of the heat transfer plate, the plate assembly comprising: a first header portion that distributes water to each of the cold fluid flow paths; a second header portion that collects water vapor from each of the cold fluid flow paths; and a second header portion that distributes heat source gas to each of the high temperature fluid flow paths. a third header section and a fourth header section that collects heat source gas from each of the high-temperature fluid flow paths, the first header section being formed on the top of the plate assembly, and the second header section being formed on the top of the plate assembly; is formed at the lower part of the plate assembly, and the meandering channel plate has a plurality of successive stages of unit channels each including an inclined channel section for allowing water to flow down and a folded channel section for reversing the fluid flow. The configuration is as follows.

According to this configuration, it is possible to provide a compact evaporator that is a vertically installed evaporator that is installed in a fuel cell system, and in which the height of the plate assembly is suppressed. More specifically, the third header section may be formed at the bottom of the plate assembly, and the fourth header section may be formed at the top of the plate assembly.

More specifically, the heat transfer plate has a first header forming hole, a second header forming hole, a third header forming hole, and a fourth header forming hole, and the heat transfer plate has a first header forming hole, a second header forming hole, a third header forming hole, and a fourth header forming hole. In each of the channels, a first auxiliary plate having a first flow hole for low temperature fluid is disposed at a position corresponding to the first header forming hole, and a first auxiliary plate having a first circulation hole for low temperature fluid is arranged at a position corresponding to the second header forming hole. A second auxiliary plate having a second flow hole for low temperature fluid is arranged, and each of the low temperature fluid passages has a third flow hole for high temperature fluid at a position corresponding to the third header forming hole. A fourth auxiliary plate having a fourth high-temperature fluid flow hole is disposed at a position corresponding to the fourth header forming hole, and the first header The second header part is formed by connecting the first header part forming hole and the first communication hole, the second header part is formed by connecting the second header part forming hole and the second communication hole, and the third header part is formed by connecting the second header part forming hole and the second communication hole. The fourth header portion may be formed by connecting the third header forming hole and the third communication hole, and the fourth header portion may be formed by connecting the fourth header forming hole and the fourth communication hole. According to this configuration, since the heat transfer plate can be manufactured using one type of press mold, it is suitable for mass production of evaporators.

More specifically, the above configuration may be such that the third auxiliary plate and the fourth auxiliary plate are processed plates integrated with the meandering channel plate. According to this configuration, it is possible to suppress the number of parts and reduce the number of steps for assembling the evaporator.

More specifically, in the above configuration, a water distribution plate is disposed in each of the low temperature fluid channels at a position corresponding to the first header forming hole, and the water distribution plate is arranged in a position corresponding to the first header forming hole. The main hole may be configured to include a main hole communicating with the hole and a peripheral edge surrounding the main hole, and a sub-hole penetrating outward from the inner wall of the main hole may be formed in the peripheral edge. According to this configuration, water is evenly distributed to each low-temperature fluid flow path through the sub-holes, and efficient steam generation can be performed while suppressing the number of stacked heat transfer plates. can.

More specifically, the plate assembly further includes a fifth header section that distributes the raw fuel gas to each of the cryogenic fluid flow paths, and the fifth header section is a part of the first header section. It may also be configured to be formed nearby. According to this configuration, it is possible to distribute raw fuel gas together with water to each of the low-temperature fluid channels, and to continuously obtain a mixed gas of raw fuel gas and water vapor from the second header section.

According to the evaporator according to the present invention, it is possible to provide a compact evaporator that is a vertically installed evaporator that is installed in a fuel cell system, and in which the height of the plate assembly is suppressed.

FIG. 1 is an explanatory diagram showing the configuration of a fuel cell system 100 according to the present embodiment. FIG. 2 is a perspective view of a hot module HM according to the present 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. It is a perspective view of hot module HM with a part 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 present embodiment. It is a side sectional view of the reformed gas generator RG. It is a block diagram of the burner vicinity in reformed gas generator RG. It is a side view of hot module HM with a part not shown. FIG. 1 is a perspective view of a cell stack 1 according to the present embodiment. FIG. 1 is a perspective view of a cell stack 1 according to the present embodiment. 1 is a plan view of a cell stack 1. FIG. FIG. 6 is a perspective view of a stack assembly 61 according to the present embodiment. 6 is a perspective view of a stack assembly 61. FIG. 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 present embodiment. FIG. 3 is an explanatory diagram regarding the connection form of each power terminal of the cell stack 1. FIG. It is a block diagram of the plate assembly 80 based on this embodiment. 7 is a perspective view of a heat transfer plate 81 used in a plate assembly 80. FIG. FIG. 3 is an explanatory diagram regarding a low-temperature fluid flow path and a high-temperature fluid flow path.

Embodiments of the present invention will be described below with reference to the drawings.

<Summary of fuel cell system configuration>
First, an overview of the configuration of the fuel cell system 100 according to this embodiment will be explained. FIG. 1 is an explanatory diagram showing the configuration of a 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 device 7, CO oxidizer (carbon monoxide oxidizer) 8, condensed water recovery tank 9, first raw fuel blower 10, first air blower 11, water pump 12, second raw fuel blower 13, second air blower 14 , a power conditioner 15, and a system controller 16.

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

The fuel cell system 100 also includes a raw fuel line La, a mixed gas line Lb, an anode fuel line Lc, an anode off gas line Ld, a cathode air line Le, a cathode off gas line Lf, a combustion gas line Lg, a burner cooling air line Lh, and a modified gas line Lh. Each line (pipe line) is provided: a quality water line Li, a starting air line Lj, and a condensed water recovery line Lw.

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

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 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.

A first air blower 11, an anode off-gas cooler 6, an air preheater 5, and a third bellows-type expansion pipe joint B3 are arranged in the middle of the pipe line Le1 in this order from the upstream side. The first air blower 11 is a device that boosts the pressure of air Aa taken in from the air intake port 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 conduit Le1, an anode off-gas cooler 6 and an anode off-gas cooler 6 are connected so as to connect the midpoint between the air intake port E3 and the anode off-gas cooler 6, and the midpoint between the air preheater 5 and the third bellows type expansion joint B3. A bypass path Le2 that bypasses the air preheater 5 is provided.

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 conduit connecting the burner 3 and the gas discharge port D1. To explain more specifically, the combustion gas line Lg includes, in order from the upstream side, a heat radiating tube Za, a pipe connecting the heat radiating tube Za and the combustion gas pipe Zb, a combustion gas pipe Zb, and a combustion gas pipe Zb. It has a pipe line (hereinafter referred to as "pipe line Lg1") that connects to the gas exhaust port D1. A fourth bellows type expansion joint B4, an air preheater 5, a CO oxidizer 8, and an evaporator 4 are arranged in the middle of the pipe line Lg1 in this order from the upstream side.

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

The starting air line Lj is a conduit that connects the air intake port E4 and the conduit Lf1, and the second air blower 14 is arranged in this conduit. The second air blower 14 is a device that boosts the pressure of the air Ac taken in from the air intake port E4 and sends it to the downstream side of the startup air line Lj, and is typically driven during startup 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 generation body composed of a solid oxide fuel cell (SOFC). A solid oxide fuel cell is a high-temperature operating type fuel cell in which the solid electrolyte, anode, and cathode that make up the power generation cell are all made of ceramic. The power generation unit integrated through the cell stack is called a cell stack. The battery output of the cell stack 1 is adjusted by the power conditioner 15 and then fed.

The reformer 2 reforms raw fuel gas Ga using water vapor, generates reformed gas Gc, and sends the reformed gas Gc to the subsequent stage side. The reformer 2 has a catalyst for steam reforming, and causes methane contained in the raw fuel gas Ga to react with steam to generate a reformed gas Gc containing carbon monoxide and hydrogen. Although steam reforming is an endothermic reaction, the reformer 2 can stably generate the reformed gas Gc by supplying heat from the burner 3.

The burner 3 burns the inflowing gas to generate heat, and discharges the combustion gas Gg generated by the combustion to the burnt exhaust 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 indirectly exchange heat between a low temperature fluid and a high temperature fluid. The air preheater 5 plays the role of preheating the air Aa in the cathode air line Le by heat exchange with the combustion gas Gg, and the anode off-gas cooler 6 plays the role of preheating the air Aa in the cathode air line Le by heat exchange with the air Aa in the cathode air line Le. It plays a role of cooling off gas Gd.

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 plays the role of recovering condensed water Wb discharged from the steam-water separation section Sa and making it reusable as reformed water Wa. The condensed water recovery tank 9 is provided with a water level detector Sb and a drain valve Sc in order to adjust the water level of the stored reformed water Wa to a predetermined range. When the water level detector Sb detects the upper limit water level, the drain valve Sc is opened, and 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 reformed water Wa is secured in the condensed water recovery tank 9. Note that in order to prevent the anode off-gas Gd from leaking to the outside during the draining operation of the reformed water Wa, the draining position by the drain valve Sc is set near the bottom of the condensed water recovery tank 9.

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

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 described above is connected to each blower 10, 11, 13, 14, water pump 12, spark rod (first electrode rod described later) of the burner 3, etc., and supplies drive power to these auxiliary machines. . When the auxiliary equipment is DC driven, the drive power supply unit supplies, for example, the power obtained by converting the output of a grid-connected inverter into AC/DC, the power obtained by converting the input from the commercial power supply into AC/DC, or the output of the cell stack 1. The circuit is configured to supply DC/DC converted power. On the other hand, when the auxiliary equipment is driven by AC, the drive power supply section is configured to supply, for example, output power from a grid-connected inverter or input power from a commercial power source. The above-mentioned auxiliary machines are driven using commercial power during startup and shutdown operations of the system, and are driven using generated power during power generation operation 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, and combustion gas pipe Zb are connected to the first It is arranged in the first region R1 inside the box X1 (see FIG. 3). 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, water pump 12, power conditioner 15, and system controller 16 are installed outside the hot module HM (in a normal temperature area). Placed.

<Overview 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 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 reformed water Wa flows into the evaporator 4 together with the raw fuel gas Ga in the mixed gas line Lb, and is heated by heat exchange in the evaporator 4 to become steam (superheated steam). The steam is mixed with the heated raw fuel gas Ga and flows into the reformer 2 as a 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.

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

Furthermore, air Ab is supplied into the cooling air line Lh in synchronization with the supply of air Aa to the cathode. Air Ab in the 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, and prevents overheating and burnout of the flame stabilizer 33 (described later). Note that if the flame temperature is maintained at a level that does not cause overheating or burnout 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 steam/water separator Sa where it is separated into steam and water, 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. Note that the portion of the anode off-gas Gd that is not condensed (anode off-gas Gd after steam and water 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.

Note that the raw fuel gas Gf is a type of hydrocarbon-containing gas. On the other hand, air Ac is a type of oxidizing agent-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.

Combustion gas Gg generated by combustion in the burner 3 is sent to the combustion gas line Lg, passes through the heat radiator Za, the combustion gas pipe Zb, the evaporator 5, the CO oxidizer 8, and the evaporator 4 in order, and the gas It is discharged to the outside of the hot module HM from the discharge port D1. Although details will be described later, the heat radiator Za and the combustion gas pipe Zb are arranged so that the reformer 2 can be effectively heated using the combustion gas Gg. Further, the combustion gas Gg in the combustion gas line Lg is used for heat exchange when passing through the evaporator 5 and the evaporator 4, and if carbon monoxide is included, the combustion gas Gg is used for heat exchange when passing through the CO oxidizer 8. Carbon oxide is converted to carbon dioxide.

<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 and outside the first box X1 (below the first pedestal X1a) is set as a second area R2 (see FIG. 1), which is a low temperature operation area, and the system A second equipment group GP2 that does not involve a chemical reaction during the power generation operation is housed. 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 accommodates a third equipment group GP3 that internally undergoes a chemical reaction only when a predetermined condition is 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 CO oxidizer 8 generates only a small amount of heat due to the catalytic reaction, there is almost no problem even if the CO oxidizer 8 is placed in the second region R2 (low-temperature operation region), thereby reducing the capacity of the first box X1. Can be suppressed.

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.

In addition, a tube insertion hole (through hole) is provided in the first pedestal X1a, and each line (pipe line) extending across the boundary between the first region R1 and the second region R2 passes through this through hole. will be placed in Thereby, fluid is transferred between the first equipment group GP1 and the second equipment group GP2 through the conduit that vertically penetrates the first pedestal X1a. In this way, in this embodiment, the piping for fluid delivery between each equipment group GP1 and GP2 has a structure that is simply attached to a pipe insertion hole drilled in the first pedestal X1a, so special seals, etc. does not require.

Furthermore, a bellows-type expansion pipe joint may be provided in the fluid conduit passing through the second equipment group GP2. The pipes that connect the conduit passing through the first pedestal X1a and the heat exchanger, and the pipes that connect the heat exchangers to each other expand and contract due to temperature changes when the system is in a cold state and during operation. Thermal stress generated by this expansion and contraction causes cracks and ruptures in the pipe body and joints, which may lead to serious problems such as leakage of flammable gas. By making the piping equipment used for the fluid connection of the second equipment group GP2 include a bellows-type expansion pipe joint, the generation of thermal stress can be suppressed as much as possible, and such problems can be avoided.

In this embodiment, as shown in FIG. 1, at least in each line extending across the boundary between the first region R1 and the second region R2 among the fluid pipes passing through the second device group GP2, the second region R2 is A bellows-type expansion pipe joint that can be expanded and contracted up and down is installed near the boundary. To explain more specifically, a first bellows-type expansion joint B1 is installed near the boundary of the mixed gas line Lb, and 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. Further, a bellows-type expansion pipe 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 piping between the equipment is constructed using required piping equipment. Next, a plurality of first columns 51 are attached on the second pedestal X2a, and the first pedestal X1a is placed and fixed on the tip of the first column 51. Next, a conduit is attached to the tube insertion hole drilled in the first pedestal X1a, and piping is constructed between this conduit and the second equipment group GP2. Next, a casing surrounding the second equipment group GP2 is attached onto the second pedestal X2a to form a semi-open second box X2, and the second box X2 is filled with a granular heat insulating material.

Next, the first equipment group GP1 is placed on the first pedestal X1a, and piping is constructed between the conduits attached to the first pedestal X1a and the first equipment group GP1, and the necessary piping equipment is installed. Use this to construct piping between equipment. Next, a casing surrounding the first equipment group GP1 is attached on the first pedestal X1a to form a closed first box X1, and a plate-shaped heat insulating material 53 is attached to the side and top of the first box X1. do. A casing that surrounds the plate-shaped heat insulating material 53 attached to the first box X1 is attached to the semi-open second box X2 to form a closed second box X2. By going through the steps described above, the hot module HM can be easily assembled.

4 to 6 are perspective views of the hot module HM from different viewpoints. 7 and 8 are side views of the hot module HM from different viewpoints, respectively. Note that in these figures, the first box X1, the second box X2, and the plate-shaped heat insulating material 53 are not shown so that the internal structure of the hot module HM can be easily understood. Furthermore, the white arrows shown in FIGS. 5 to 8 schematically represent 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 arranged in the . 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 is performed between the surfaces of these two distribution manifolds by radiant heat transfer or convection heat transfer. Further, by arranging each distribution manifold Ma, Mb near the cell stack assembly 61, heat exchange is performed between the surfaces of the equipment by radiant heat transfer or convection heat transfer. As a result, the temperatures of the anode fuel (reformed gas Gc) and cathode air (air Aa) supplied to the cell stack 1 are equalized, and the temperature can be raised to near the operating temperature of the cell stack 1, so that the power generation cell An efficient power generation reaction can be carried out in total.

As shown in FIG. 6, in the area sandwiched between the left and right cell stack assemblies 61 on the rear side of the reformer 2, a first collection manifold Mc and a second collection manifold Md are arranged so as to extend vertically. It is located. That is, each of the cell stack assembly 61, the first collection manifold Mc, and the second collection manifold Md is arranged so as to surround the outer cylinder 21 of the reformer 2.

In this way, each cell stack 1, the first collection manifold Mc, and the second collection manifold Md are arranged in the vicinity of the reformer 2, and it is possible to efficiently provide waste heat accompanying the power generation reaction to the reformer 2. It is possible. In particular, the first collection manifold Mc has a role of actively providing waste heat contained in the anode off-gas Gd to the reformer 2. Further, the second collection manifold Md has a role of actively providing waste heat contained in the cathode off-gas Ge to the reformer 2. As a result, the amount of heat absorbed by the catalyst layer in the reformer 2 increases significantly, so the efficiency of the steam reforming reaction increases, the amount of catalyst used is reduced, and the reformer 2 can be made smaller.

<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 proximal end cover plate 24, and a distal end cover plate 25.

The outer cylinder 21 and the inner cylinder 22 are formed into a cylindrical shape with a common axis extending vertically, and the lengths in the vertical direction are approximately the same, but the diameter of the outer cylinder 21 is larger than the diameter of the inner cylinder 22. big. The outer cylinder 21 and the inner cylinder 22 form a reaction vessel 2a having a double cylinder structure, in which the inner cylinder 22 is placed inside the outer cylinder 21. A catalyst packed bed 23 filled with a catalyst for steam reforming is provided between the outer cylinder 21 and the inner cylinder 22, that is, inside the reaction vessel 2a.

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 proximal end cover plate 24 and the distal end cover plate 25 are annular end plates, and the annular cross-sectional shape of the annular end plate is a dish shape, a regular semi-ellipse, or an approximate semi-ellipse. By using an annular end plate for the lid 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. Note that the cross-sectional shape of the above-mentioned end plate is one specified in JIS B 8247 "End plate for pressure vessels", excluding the flat end plate.

Further, in a portion of the outer cylinder 21 slightly above the intake port 21a, an elastic absorbing portion 21c having a bellows structure is formed. By providing the expansion/contraction absorbing portion 21c, expansion/contraction due to temporal temperature changes or positional temperature distribution of the outer tube 21 is absorbed. Therefore, the reaction vessel 2a containing the catalyst can be used for a long period of time while avoiding damage or breakage due to thermal stress. Note that it is preferable to use a commercially available bellows type expansion pipe joint as the expansion/contraction absorbing portion 21c, and the outer cylinder 21 can be manufactured at low cost by joining this pipe joint and a straight pipe.

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

The first gas cylinder 31 and the second gas cylinder 32 are formed into a cylindrical shape having 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 from the upper end of the second gas cylinder 32, and the lower part of the first gas cylinder 31 is arranged inside the second gas cylinder 32. ing. The upper end of the first gas cylinder 31 is closed, and the gap between the first gas cylinder 31 and the second gas cylinder 32 is closed 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 into a truncated cone shape with a distal end expanding downward (downstream of the flow of gas to be combusted). Further, the flame stabilizer 33 has multiple rows of through holes 33a spaced apart in the expansion direction. Further, the outer diameter of the flame stabilizer 33 and the inner diameter of the second gas cylinder 32 are formed to have approximately the same diameter, so that the burner 3 burns the first burner gas Gx and the second burner gas Gy, It is possible to 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, the burner 3 causes the first electrode rod 41 to function as a spark rod and the second electrode rod 42 to function as a ground rod when igniting gas. On the other hand, when detecting a flame, the burner 3 causes the first electrode rod 41 to function as a flame rod and causes the second electrode rod 42 to function as a ground rod. Therefore, according to the burner 3, by using the electrode pair 40x consisting of the first electrode rod 41 and the second electrode rod 42 and configuring the gas ignition mechanism and the flame detection mechanism to be switchable, a reliable and safe combustion operation can be achieved. It can be carried out.

The heat radiating tube Za is formed in a cylindrical shape having a common axis with the inner tube 22, and the outer diameter of the heat radiating tube Za is smaller than the inner diameter of the inner tube 22. Further, the upper end of the heat radiating cylinder Za is connected to the lower end of the second gas cylinder 32 inside the inner cylinder 22, and the lower end of the heat radiating cylinder Za projects further downward than the lower end of the inner cylinder 22. Note that the heat radiator Za can also be viewed 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 radiating cylinder Za is inserted into the inner cylinder 22 so that the inner cylinder 22 and the surface thereof are separated from each other in the entire circumferential direction. In this way, a gap is provided between the outer surface of the heat radiating tube Za and the inner surface of the inner tube 22. Therefore, heat transfer when providing thermal energy from the inner cylinder 22 side to the catalyst packed bed 23 for the steam reforming reaction is performed by radiant heat transfer from the heat radiating cylinder Za, and is not accompanied by heat conduction. Thereby, it is possible to use the reaction vessel 2a for a long period of time while avoiding damage or breakage of the reaction vessel 2a containing the catalyst due to thermal stress.

In the reformer 2, an intake port 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 a reformed gas inlet 21a is provided near the upper end of the outer cylinder 21. A Gc outlet 21b is provided. The mixed gas Gb taken in between the outer tube 21 and the inner tube 22 from the intake port 21a is reformed when passing through the catalyst packed bed 23, and taken out from the outlet 21b as reformed gas Gc. Thus, in this embodiment, the intake port 21a is provided on the side corresponding to the distal end side of the heat radiating tube Za, and the outlet port 21b is provided on the side corresponding to the base end side of the heat radiating tube Za.

Here, since the thermal energy of the combustion gas Gg is used for heat absorption accompanying the steam reforming reaction, the temperature of the combustion gas Gg decreases from the base end side to the distal end side of the heat radiating cylinder Za. become. Considering this point, in this embodiment, the arrangement of the intake port 21a and the extraction port 21b is set as described above, so that the mixed gas Gb that flows in from the intake port 21a is preheated by the combustion gas Gg whose temperature has decreased, and then It is reformed using the thermal energy of high-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, since the flows of the mixed gas Gb and the reformed gas Gc and the flow of the combustion gas are opposed to each other, an efficient steam reforming reaction can be performed.

However, the arrangement of the intake port 21a and the outlet port 21b is reversed from this embodiment, and the intake port 21a is provided on the side corresponding to the base end side of the heat radiating tube Za, and the outlet port 21b is provided on the side corresponding to the base end side of the heat radiating tube Za. It may also be provided on the side corresponding to. In this case, the mixed gas Gb flowing in from the intake port 21a is instantaneously preheated by the high-temperature combustion gas Gg, and then reformed using the thermal energy of the combustion gas Gg whose temperature has decreased slightly. In this way, by making the flow of the mixed gas Gb and reformed gas Gc and the flow of the combustion gas Gg parallel, the preheating effect of the mixed gas Gb is high, and the heating capacity of the evaporator 4 for preparing the mixed gas Gb is increased. It is possible to design the evaporator 4 with reduced heat exchange capacity, and it is expected that the cost of the evaporator 4 will be reduced.

<Combustion gas pipe>
Next, the configuration etc. of the combustion gas pipe Zb will be explained in more detail. FIG. 12 is a side view of the hot module HM with the boxes X1 and X2, the plate-shaped heat insulating material 53, the manifolds Ma to Md, etc. not shown, so that the arrangement of the combustion gas pipes Zb can be more easily understood. It is.

As shown in this figure, the combustion gas pipe Zb consists of a folded pipe line in which vertically extending straight pipes are U-turned at the top so that they are lined up left and right (in other words, in parallel), and is arranged on the rear side of the reformer 2. There is. The left and right straight pipes connected at the upper side extend from near the lower end of the reformer 2 to near the upper end, and are disposed directly opposite to the outer cylinder 21 of the reformer 2. As shown by the broken line arrow in FIG. 12, the combustion gas Gg flows upward through the straight pipe on the right side and downward through the straight pipe on the left side.

Thereby, the combustion gas Gg generated during operation of the burner 3 flows through the heat radiating tube Za and the combustion gas pipe Zb in order, and can provide combustion heat from 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 decreases significantly, making it possible to supply the combustion gas Gg with a reduced temperature to the preheating heat exchanger, making the heat exchanger cheaper. It can be manufactured from suitable materials (for example, 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.

Further, as shown in FIG. 12, the left combustion gas pipe Zb is placed directly opposite the right side of the left cell stack assembly 61, and the right side combustion gas pipe Zb is placed near the left side of the right cell stack assembly 61. They are placed facing each other. Thereby, the fuel cell system 100 can shorten the start-up operation time.

That is, in a reforming fuel cell system that uses steam reforming, steam (superheated steam) may be used to raise the temperature of the reformer and the cell stack during startup operation of the fuel cell system. In this case, water vapor is generated by heating water inside the evaporator using combustion gas generated by combustion in the burner as a heat source for the evaporator. However, heating using only water vapor has a very long start-up run time, typically 8 hours or more. In this regard, in this embodiment, since the combustion gas pipe Zb is arranged near the reformer 2 and the cell stack assembly 61, heat radiation during burner combustion causes the cold reformer 2 and the cell stack The assembly 61 is heated indirectly. Therefore, the start-up operation time can be shortened to, for example, about 4 hours.

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

Furthermore, in this embodiment, by forming the combustion gas pipe Zb as a folded pipe, combustion heat can be repeatedly applied from the outside of the reformer 2, and the amount of heat absorbed in the catalyst layer further increases. Therefore, by reducing the amount of catalyst used and downsizing the reformer 2, the material cost of the hot module HM can be effectively reduced. Note that the straight portion of the folded pipe may be laid along the axial direction of the reformer 2, or may be laid perpendicular to the axial direction of the reformer 2. Further, in this embodiment, the number of turns of the folded conduit is one, but the number of turns of the folded conduit may be plural.

<Cell stack>
Next, the configuration etc. of the cell stack 1 will be explained in more detail. 13 and 14 are perspective views of the cell stack 1, and FIG. 14 is a plan view of the cell stack 1.

As shown in FIGS. 13 to 15, the cell stack 1 includes a stacked section 75 in which a predetermined number of flat power generation cells are stacked on the left and right sides, a first end plate 76a provided at the left end of the stacked section 75, and a stacked section 75. A second end plate 76b is provided at the right end of the. The first end plate 76a and the second end plate 76b are provided as a pair of end plates facing left and right with the laminated portion 75 in between, and have a substantially rectangular shape when viewed from the left.

A flanged gas port 72 is arranged 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 inflow port 72a, a cathode air inflow port 72b, an anode off-gas outflow port 72c, and a cathode off-gas outflow port 72d. There is. Each flanged gas port 72 has a flange portion 72x that extends in the radial direction from the entire circumference of the left (outside) edge.

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

On the front side of the stacked section 75, a first power terminal 74a and a second power terminal 74b, which are plate-shaped with the top and bottom in the width direction, are arranged as terminals for outputting the power generated by the power generation cells of the stacked section 75. . Note that the first power terminal 74a and the second power terminal 74b are power terminals having mutually different polarities. The first power terminal 74a protrudes forward from the front side of the laminated portion 75, and has an end portion 74a1 bent to the left. The second power terminal 74b protrudes forward from a position closer to the lower left than the first power terminal 74a on the front side of the laminated portion 75, and has an end portion 74b1 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 explained in more detail. 16 and 17 are perspective views of the left stack assembly 61 seen from different viewpoints, respectively. In the example of this embodiment, the cell stacks 1 in the cell stack assembly 61 on the right side are arranged upside down from the cell stacks 1 in the cell stack assembly 61 on the left side. As a result, each cell stack assembly 61 provided on the left and right sides with the reformer 2 in between is configured such that each power terminal 74a, 74b is located at the front, and the flanged gas port 72 is located at the inside in the left-right direction. Ru.

The stack assembly 61 has a structure in which a plurality of cell stacks 1 are stacked vertically using open racks 62. Thereby, it is possible to minimize the installation area of the cell stack assembly 61 and, by extension, the installation area of the hot module HM. Therefore, according to the present embodiment, it is possible to construct the fuel cell system 100 that can be easily installed in a narrow place, such as an empty space in an existing facility. Further, by mounting a plurality of cell stack assemblies 61 on the hot module HM, it is easy to increase the power generation output capacity 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.

Furthermore, the open rack 62 described above is designed to be able to mount a specified number of cell stacks 1 (four in the example of this embodiment), but instead of the open rack, one cell stack 1 can be mounted. An open rack constructed by assembling a plurality of unit racks may also be used. FIG. 18 illustrates a state in which the cell stack 1 is mounted on a unit rack 62a that can form such an open rack.

The unit rack 61a includes a stage board 63a, which has a configuration equivalent to one stage of the stage board 63 in the open rack 62, and four pillars, which have a configuration equivalent to one stage of the four pillars 64 in the open rack 62. The unit racks 61a can be vertically stacked and fixed together. As a result, in the same manner as in the case of the open rack 62, the required number of cell stacks 1 are accommodated in each unit rack 61a, and each of the already accommodated unit racks 61a (stack holder) is stacked and fixed. By doing so, it is possible to obtain something equivalent to the 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.

Here, FIG. 19 shows an example of the configuration of branch pipes extending from each manifold Ma to Md (generally referred to as "manifold Mx" for convenience). Each of the branch pipes BP shown in this figure extends from the manifold Mx and is provided with 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.

In the example shown in FIG. 19(B), a state in which one branch pipe BP extends from the manifold Mx to one cell stack 1 is partially shown, and this branch pipe BP has a curved portion CV3. It is included. This curved portion CV3 also has a planar pipe structure. That is, in the entire region of the curved portion CV3, 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). Further, a bellows-type expansion pipe joint Bp1 is provided in the middle of the branch pipe BP, so that expansion and contraction of the branch pipe BP can be absorbed.

In the example shown in FIG. 19(C), 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. CV4 is included, and the other branch pipe BP includes a curved portion CV5. Both of these curved portions CV4 and CV5 have a three-dimensional (that is, three-dimensional) pipe structure. That is, in either of the curved portions CV4 and CV5, the cross-sectional center of the branch pipe BP is not included in the same plane in 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 in the example shown in FIGS. 19(A) or 19(B), when the branch pipe BP of the manifold Mx is provided with a curved portion having a planar pipe structure, the horizontal direction of the branch pipe BP (hot module HM It is possible to effectively absorb the expansion and contraction of the pipe that occurs in the direction perpendicular to the vertical direction of the pipe. This eliminates the problem of gas leakage caused by stress acting on the joint with the flanged gas port 72.

On the other hand, if the branch pipe BP of the manifold Mx is provided with a curved part having a three-dimensional pipe structure, as in the example shown in FIG. Expansion and contraction of the pipe that occurs in the vertical direction (vertical direction of the hot module HM) can also be effectively absorbed. This eliminates the problem of gas leakage caused by stress acting on the joint with the flanged gas port 72. Which pipe structure curved portions are provided in the branch pipes of each manifold Ma to Md can be determined depending on, for example, the specifications of the hot module HM.

<Power terminal and its connection form>
Furthermore, in both the left and right stack assemblies 61, the power terminals 74a and 74b in each cell stack 1 protrude forward, and the ends 74a1 and 74b1 of these power terminals have their positions in the front-rear direction and left-right direction. They are arranged so that they are the same. Moreover, in the cell stacks 1 in the same 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 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 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. 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 collectively output the generated power 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, FIG. 20 schematically shows the connection form of each power terminal 74a, 74b. As shown in the 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 assembly 61 on the left side, the first power terminal 74a is provided above the second power terminal 74b. In the cell stack 1, 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 in order to prevent problems caused by expansion/contraction in the vertical direction due to the temperature difference between the hot module HM when it is in a cold state and during power generation operation. In the example of this embodiment, the stretchable absorbing portion 78a1 is a U-shaped curved portion when viewed in the left-right direction as shown in FIG. 8, but it may also be a V-shaped bent portion or the like. By employing the main bus bar 78a having the expansion/contraction absorbing portion 78a1, thermal stress can be alleviated, stable power generation operation can be realized, and excessive force can be prevented from being applied to the cell stack 1 at each stage. You can also do it.

The sub-bus bar 78b is made of a metal plate having an expansion/contraction absorbing portion 78b1 in order to prevent problems caused by expansion and contraction in the horizontal direction due to the temperature difference between the hot module HM when it is in a cold state and when it is in power generation operation. In the example of this embodiment, the stretchable absorbing portion 78b1 is a U-shaped curved portion when viewed in the vertical direction, 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, stable power generation operation can be realized, and excessive force can be prevented from being applied to the cell stack 1 at the top stage. can.

<Evaporator>
Next, the configuration etc. of the evaporator 4 will be explained in more detail. FIG. 21 is a configuration diagram of a plate assembly 80 functioning as the evaporator 4, with a left side view shown on the left side, a front view shown in the center, and a right side view shown on the right side.

The plate assembly 80 has a plurality of heat transfer plates 81 stacked in the front-rear direction between a first end plate 82a and a second end plate 82b which are arranged opposite each other in the front and back, and each end plate 82a, 82b and each heat transfer The plate 81 is joined and integrated. As will be described later, each of these heat transfer plates 81 has a low-temperature fluid flow path through which the low-temperature fluid (raw fuel gas Ga and reformed water Wa) in the evaporator 4 flows, and a low-temperature fluid flow path through which the high-temperature fluid (combustion gas Gg) in the evaporator 4 flows. ) is formed in one of the hot fluid flow paths.

FIG. 22 is a perspective view of the heat transfer plate 81. As shown in this figure, the heat transfer plate 81 includes a substantially rectangular flat plate portion 81a (heat transfer surface portion) whose longitudinal direction is the vertical direction, and a substantially uniform height rearward from the edge of the entire circumference of the flat plate portion 81a. It has a projecting frame portion 81b. Each of the front and back planes of the flat plate portion 81a functions as a heat transfer surface parallel to the vertical direction.

A first header forming hole 83a1 and a fifth header forming hole 83e1 are provided at a position near the upper right of the flat plate portion 81a. Further, a second header forming hole 83b1 is provided at a lower left position of the flat plate part 81a, a third header forming hole 83c1 is provided at a lower right position of the flat plate part 81a, and a third header forming hole 83c1 is provided at a lower left position of the flat plate part 81a. A fourth header forming hole 83d1 is provided at a closer position.

In each heat transfer plate 81, predetermined members are arranged inside the frame portion 81b, and one of a low temperature fluid flow path shown on the left side of FIG. 23 and a high temperature fluid flow path shown on the right side of FIG. 23 is formed. be done. Note that an enlarged view of the vicinity of the water distribution plate 86 is shown in the upper frame of FIG.

The parts constituting the low temperature fluid flow path include the meandering flow path plate 85, the water distribution plate 86 (the part outside the broken line Q1 shown in FIG. 23), and the third auxiliary plate 87c (the part below the broken line Q3 shown in FIG. 23). ), and the fourth auxiliary plate 87d (the part above the broken line Q2 shown in FIG. 23 and excluding the water distribution plate 86) are used.

A meandering channel 85a is formed in the meandering channel plate 85, which is widely disposed in the central region of the heat transfer plate 81, so as to extend in a meandering manner from the upper side to the lower side. The meandering flow path 85a can be formed by punching, for example, by laser processing, and if the meandering flow path plate 85 is manufactured in this way, mass production is possible with fewer man-hours, and processing costs can also be kept low. be. The meandering channel 85a generally has an inclined channel section Ch1 that is inclined diagonally downward so that the fluid flows down from one side near the left end and near the right end to the other, and the flow of the fluid is reversed at the end of the inclined channel section Ch1. A plurality of stages of unit channels Ch each including a folded channel section Ch2 are formed continuously in the vertical direction.

The water distribution plate 86 is a plate member disposed at a position corresponding to the first header forming hole 83a1, and has a main hole communicating with the first header forming hole 83a1, as shown in the upper frame of FIG. 86a, and a peripheral portion 86b surrounding the main hole 86a. Further, a sub-hole 86c is formed in the peripheral portion 86b and penetrates outward from the inner wall of the main hole 86a. The sub-hole 86c extends downward from the main hole 86a and is connected to the upper end portion 85a1 of the meandering channel.

The third auxiliary plate 87c is disposed below the meandering channel plate 85, has a third communication hole 89c at a position corresponding to the third header forming hole 83c1, and has a third communication hole 89c at a position corresponding to the third header forming hole 83b1. It has a second header corresponding hole 83b2 at a corresponding position. The second header corresponding hole 83b2 is connected to the lower end of the meandering channel 85a.

The fourth auxiliary plate 87d is disposed above the meandering channel plate 85, and has a fourth communication hole 89d at a position corresponding to the fourth header forming hole 83d1, which corresponds to the fifth header forming hole 83e1. The upper end portion 85a1 of the meandering channel is located at the position where the meandering flow path is located. The upper end portion 85a1 of the meandering channel is connected to the upper end of the meandering channel 85a in the meandering channel plate 85.

The heat transfer fins 88, the first auxiliary plate 87a, and the second auxiliary plate 87b are used as components constituting the high-temperature fluid flow path. In the example of this embodiment, the heat transfer fins 88 are corrugated fins in which a large number of channels extending in the vertical direction are formed, and are widely arranged in the central region of the heat transfer plate 81.

The first auxiliary plate 87a is arranged above the heat transfer fins 88, has a first communication hole 89a at a position corresponding to the first header forming hole 83a1, and has a first communication hole 89a at a position corresponding to the fifth header forming hole 83e1. It has a fifth communication hole 89e at a position, and a fourth header-corresponding hole 83d2 at a position corresponding to the fourth header-forming hole 83d1. The fourth header corresponding hole 83d2 is connected to the entire upper end of the heat transfer fin 88.

The second auxiliary plate 87b is arranged below the heat transfer fins 88, has a second communication hole 89b at a position corresponding to the second header forming hole 83b1, and corresponds to the third header forming hole 83c1. A hole 83c2 corresponding to the third header portion is provided at the position where the third header portion corresponds to the third header portion. The third header corresponding hole 83c2 is connected to the entire lower end of the heat transfer fin 88.

In the plate assembly 80, between each end plate 82a, 82b, a heat transfer plate 81 in which a low temperature fluid flow path is formed and a heat transfer plate 81 in which a high temperature fluid flow path is formed are alternately stacked and integrated. has been made into In the plate assembly 80 formed in this way, a low temperature fluid flow path is formed on one heat transfer surface side of the heat transfer plate 81 (flat plate portion 81a), and a high temperature fluid flow path is formed on the other heat transfer surface side. It can also be seen that it is being formed.

Further, as shown in FIG. 21, each end plate 82a, 82b is formed into a substantially plate shape whose outer edge generally coincides with the heat transfer plate 81 when viewed from the front, and the first end plate 82a provided on the front side has a Fluid ports corresponding to the first and fifth header forming holes 83a1 and 83e1 are provided, and the second end plate 82b provided on the rear side has the second, third and fourth header forming holes 83b1, Fluid ports corresponding to 83c1 and 83d1 are provided.

As a result, the plate assembly 80 has a first header part 83a formed by connecting the first header part forming hole 83a1, the first communication hole 89a, and the main hole 86a in the front-rear direction. The first end plate 82a is open to the front. The plate assembly 80 also has a second header part 83b formed by connecting a second header part forming hole 83b1, a second header part corresponding hole 83b2, and a second communication hole 89b in the front-rear direction. The portion 83b opens rearward in the second end plate 82b.

Further, the plate assembly 80 has a third header part 83c formed by connecting a third header part forming hole 83c1, a third header part corresponding hole 83c2, and a third communication hole 89c in the front-rear direction. The portion 83c opens rearward in the second end plate 82b. The plate assembly 80 also has a fourth header part 83d formed by connecting a fourth header part forming hole 83d1, a fourth header part corresponding hole 83d2, and a fourth communication hole 89d in the front-rear direction. The portion 83d opens rearward in the second end plate 82b.

The plate assembly 80 also has a fifth header part 83e formed by connecting a fifth header part forming hole 83e1, a fifth communication hole 89e, and an upper end part 85a1 of the meandering channel in the front-rear direction. The portion 83e opens forward in the first end plate 82a. As described above, the first header part 83a and the fifth header part 83e are formed at the top right of the plate assembly 80, and the second header part 83b is formed at the bottom left of the plate assembly 80. The third header portion 83c is formed at the bottom right of the plate assembly 80, and the fourth header 83d is formed at the top left of the plate assembly 80.

The header forming holes 83a1 to 83e1, the communication holes 89a to 89e, and the header corresponding holes 83b2 to 83d2 can be formed, for example, by laser processing. In addition, in the stacking of the heat transfer plates 81, positions corresponding to the header forming holes where fluid distribution/collection is unnecessary (that is, the third header forming hole 83c1 and the fourth header forming hole on the low temperature fluid flow path side) 83d1, and positions corresponding to the first header forming hole 83a1, second header forming hole 83b1, and fifth header forming hole 83e1 on the high temperature fluid flow path side, auxiliary plates 87a to 87d are provided. is being held.

The auxiliary plate prevents unnecessary fluid from entering the fluid flow path by joining and connecting the edges of the header part forming hole and the circulation hole by brazing etc., making it possible to easily form an appropriate header part. can do. If such a configuration is adopted, the heat transfer plate 81 can be manufactured using one type of press mold, which is suitable for mass production of the evaporator 4. Further, in this embodiment, the meandering channel plate 85, the water distribution plate 86, the third auxiliary plate 87c, and the fourth auxiliary plate 87d are integrally manufactured by punching a single plate by laser processing or the like. . By manufacturing the respective parts integrally in this way, the number of parts can be suppressed and the number of steps required to assemble the evaporator 4 can be reduced.

Reformed water Wa is supplied to the first header section 83a, and raw fuel gas Ga is supplied to the fifth header section 83e. The reformed water Wa supplied to the first header section 83a is evenly distributed to the water distribution plate 86 of each low-temperature fluid flow path, and flows down to the uppermost stage of the meandering flow path 85a through the main hole 86a and the sub-hole 86c. . This reformed water Wa is heated while traveling through the meandering flow path 85a, becomes water vapor, and reaches the second header portion 83b.

Note that the sub-hole 86c in the water distribution plate 86 may be configured to extend upward from the main hole 86a and then connect to the upper end portion 85a1 of the meandering channel via a folded channel. By discharging the reformed water Wa supplied to the main hole 86a upward, a relatively high flow resistance is generated when pushing out the reformed water Wa from the sub-hole 86c. Therefore, compared to the configuration in which the reformed water Wa is discharged downward as shown in FIG. 23, more even water distribution is possible.

The raw fuel gas Ga supplied to the fifth header section 83e is also equally distributed to each low-temperature fluid flow path, and is heated while traveling along the meandering flow path 85a at the same time as the reformed water Wa, and reaches the second header section 83b. . In this way, the plate assembly 80 is configured to evaporate water in the raw fuel gas Ga, and a mixed gas Gb of the raw fuel gas Ga and water vapor is continuously obtained in a superheated state in the second header part 83b. It will be done. This mixed gas Gb can be supplied to the reformer 2 as is.

On the other hand, combustion gas Gg is supplied to the third header section 83c as a heat source gas. The combustion gas Gg supplied to the third header section 83c is evenly distributed to each high-temperature fluid channel, flows upward through each channel in the heat transfer fins 88, and is collected at the fourth header section 83d. It is discharged to pipe Lg1.

At this time, since the meandering path 85a of each low-temperature fluid flow path faces the heat transfer fins 88 of the adjacent high-temperature fluid flow path in the front-rear direction via the heat transfer plate 81, the meandering path 85a of each low-temperature fluid flow path is modified using the heat of the combustion gas Gg. The quality water Wa and the raw fuel gas Ga are efficiently heated.

In addition, since the reformed water Wa and the raw fuel gas Ga flow downward through the meandering path 85a, and the combustion gas Gg flows upward through the heat transfer fins 88, they exchange heat in a counterflow manner. As a result, in the lower region of the plate assembly 80, the water vapor (reformed water Wa) is heated by the high temperature heat source gas (combustion gas Gg) immediately introduced from the third header part 83c, so that the superheated steam is heated from the second header part 83b. can be taken out. This superheated steam is useful in the steam reforming reaction of hydrocarbon fuel in the reformer 2.

<Effects of the present invention and other modifications>
As explained above, the evaporator 4 for steam generation installed in the fuel cell system 100 has front and back heat transfer surfaces that are substantially parallel to the vertical direction between the pair of end plates 82a and 82b that are arranged opposite to each other. A plate assembly 80 is formed by laminating a plurality of heat transfer plates 81 having the same structure, and joining and integrating end plates 82a, 82b and heat transfer plates 81, and a plate assembly 80 formed on one heat transfer surface side of the heat transfer plate 81. It includes a serpentine flow path plate 85 built into each of the low temperature fluid flow paths, and a heat transfer fin 88 built into each of the high temperature fluid flow paths formed on the other heat transfer surface side of the heat transfer plate 81.

The plate assembly 80 also includes a first header section 83a that distributes water (reformed water Wa) to each of the low temperature fluid flow paths, a second header section 83b that collects water vapor from each of the low temperature fluid flow paths, and a high temperature It has a third header section 83c that distributes heat source gas (combustion gas Gg) to each of the fluid channels, and a fourth header section 83d that collects heat source gas from each of the high temperature fluid channels. The first header section 83a is formed at the upper part of the plate assembly 80, the second header section 83b is formed at the lower part of the plate assembly 80, and the meandering channel plate 85 has an inclined channel section Ch1 and a channel section Ch1 through which water flows down. A plurality of stages of unit channels Ch each including a folded channel section Ch2 that reverses the fluid flow are continuously formed.

Therefore, even if the height of the plate assembly 80 is suppressed, the meandering flow path ensures sufficient contact time between the heating surface and the water film, so that a compact evaporator 4 with high evaporation efficiency is realized. Furthermore, since the water film flowing down the meandering flow path can be gradually heated, the evaporation rate becomes slow, and water vapor with stable pressure can be obtained.

Note that among heat transfer fins, corrugated fins can be manufactured only by bending a metal plate, but offset fins require at least three steps (bending → cutting → bending). Therefore, in a configuration in which heat transfer fins that require a large number of processes are incorporated into a low-temperature fluid channel or a high-temperature fluid channel, there are cases where the processing cost of the auxiliary parts becomes high. In this embodiment, the meandering flow path plate 85 is installed in the low temperature fluid flow path, while relatively inexpensive corrugated fins are installed as the heat transfer fins 88 in the high temperature fluid flow path. In particular, since the meandering channel plate 85 can be manufactured by punching using laser processing or the like, it can be mass-produced with a small number of man-hours, and the processing cost is also low.

Further, in the evaporator 4, the third header part 83c is formed at the lower part of the plate assembly 80, and the fourth header part 83d is formed at the upper part of the plate assembly 80. Therefore, the water distributed from the first header section 83a evaporates while flowing downward through each of the low-temperature fluid channels, and is collected at the second header section 83b, while the water is distributed from the third header section 83c. The heat source gas flows upward through each of the high-temperature fluid channels and is collected at the fourth header section 83d. That is, the evaporator 4 is configured to exchange heat between water and heat source gas by counterflow. In the lower region of the plate assembly 80, water vapor is heated by the high-temperature heat source gas just introduced from the third header section 83c, so superheated steam can be taken out from the second header section 83b. This superheated steam is useful in steam reforming reactions of hydrocarbon fuels.

In the evaporator 4, the heat transfer plate 81 has a first header forming hole 83a1, a second header forming hole 83b1, a third header forming hole 83c1, and a fourth header forming hole 83d1. Furthermore, in each of the high-temperature fluid flow paths, a first auxiliary plate 87a having a first flow hole 89a for low-temperature fluid is arranged at a position corresponding to the first header-forming hole 83a1, and a first auxiliary plate 87a having a first flow hole 89a for low-temperature fluid is arranged at a position corresponding to the first header-forming hole 83a1. A second auxiliary plate 87b having a second flow hole 89b for low temperature fluid is arranged at a position corresponding to 83b1. Furthermore, in each of the low temperature fluid flow paths, a third auxiliary plate 87c having a third flow hole 89c for high temperature fluid is arranged at a position corresponding to the third header forming hole 83c1, and a fourth header forming hole. A fourth auxiliary plate 87d having a fourth communication hole 89d for high temperature fluid is arranged at a position corresponding to 83d1.

The first header part 83a is formed by connecting the first header part forming hole 83a1 and the first communication hole 89a, and the second header part 83b is formed by connecting the second header part forming hole 83b1 and the second communication hole 89b. The third header part 83c is formed by connecting the third header part forming hole 83c1 and the third communication hole 89c, and the fourth header part 83d is formed by connecting the fourth header part forming hole 83d1 and the fourth communication hole 89d. Formed by concatenation.

Each of the header forming holes 83a1 to 83d1 is provided in advance by laser processing on the heat transfer plate 81. When stacking the heat transfer plates 81, auxiliary plates 87a to 87d are sandwiched at positions corresponding to the header forming holes 83a1 to 83d1 for fluid flow paths that do not require fluid distribution/collection. Each of the auxiliary plates 87a to 87d is a separate part with corresponding communication holes 89a to 89d provided by laser machining, and the edges of each of the header forming holes 83a1 to 83d1 and each communication hole 89a to 89d are attached by brazing or the like. By joining and connecting, corresponding header parts 83a to 83d can be easily formed. This configuration is suitable for mass production of the evaporator 4 because the heat transfer plate 81 can be manufactured using one type of press mold.

Further, the third auxiliary plate 87c and the fourth auxiliary plate 87d are processed plates integrated with the meandering channel plate 85. When the three parts of the meandering channel plate 85, the third auxiliary plate 87c, and the fourth auxiliary plate 87d are integrated in this way, the integrated product is manufactured by punching out a single plate material by laser processing. Is possible. Therefore, the number of parts can be suppressed and the number of steps required to assemble the evaporator 4 can be reduced.

Further, in the evaporator 4, a water distribution plate 86 is disposed in each of the low temperature fluid flow paths at a position corresponding to the first header forming hole 83a1, and the water distribution plate 86 communicates with the first header forming hole. It consists of a main hole 86a and a peripheral portion 86b surrounding the main hole 86a. A sub-hole 86c is formed in the peripheral portion 86b and penetrates outward from the inner wall of the main hole 86a.

Water supplied from the first header section 83a is distributed to the low temperature fluid flow path through the main hole 86a and the sub-hole 86c in each of the water distribution plates 86. The water sent out from each sub-hole 86c flows down to the uppermost stage (upper end portion 85a1) of the meandering channel. Thereby, it is possible to distribute water evenly to the low-temperature fluid flow path, suppress the number of stacked heat transfer plates 81, and perform efficient steam generation. Note that, as in the example of this embodiment, the water distribution plate 86 is preferably configured to be integrated with three parts: the meandering channel plate 85, the third auxiliary plate 87c, and the fourth auxiliary plate 87d.

The plate assembly 80 further includes a fifth header section 83e that distributes the raw fuel gas Ga to each of the low temperature fluid channels, and the fifth header section 83e is formed near the first header section 83a. In this way, the plate assembly 80 introduces the reformed water Wa from the first header part 83a while introducing the raw fuel gas Ga (hydrocarbon fuel such as city gas) from the fifth header part 83e. The structure is such that water evaporates in the raw fuel gas Ga. Thereby, the mixed gas Gb of raw fuel gas Ga and water vapor can be continuously obtained from the second header portion 83b. This mixed gas Gb can be supplied to the reformer 2 as is.

The evaporator 4 of this embodiment is configured to supply the raw fuel gas Ga to the low temperature fluid flow path together with the reformed water Wa to generate a mixed gas Gb of the raw fuel gas Ga and water vapor. However, the present invention is not limited to this, and the evaporator 4 may generate only superheated steam, and the steam and raw fuel gas Ga may be mixed on the downstream side of the evaporator 4 to generate the mixed gas Gb. In this case, it is preferable to preheat the raw fuel gas Ga using a fuel preheater or the like to a temperature higher than that of water vapor before mixing.

Note that although the system of this embodiment is a single-stage fuel cell system, the present invention is also applicable to a multi-stage fuel cell system. For example, in the case of a two-stage fuel cell system, a front-stage cell stack and a rear-stage cell stack are provided, and the anode off-gas (including unreacted fuel components) discharged from the front-stage cell stack is collected. The subsequent cell stack is configured to generate electricity using the power source.

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 solid oxide fuel cell systems.

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 21 Outer cylinder 21a Inlet 21b Outlet 21c Expandable absorption section 22 Inner cylinder 23 Catalyst packed bed 24 Base end cover plate 25 End side cover Plate 31 First gas cylinder 32 Second gas cylinder 33 Flame stabilizer 40 Ignition/flame detection circuit 40a Gas ignition part 40b Current detection part 40c1 First switch 40c2 Second switch 40x Electrode pair 51 First pillar 52 Second pillar 53 Plate shaped heat insulating material 61 cell stack assembly 62 open rack 62a unit rack 63 stage board 63a stage board 64 pillar part 64a pillar part 71 support plate 72 flanged gas port 72a anode fuel inflow port 72b cathode air inflow port 72c anode off-gas outflow port 72d Cathode off-gas outflow port 72x Flange portion 74a First power terminal 74a1 End portion of first power terminal 74b Second power terminal 74b1 End portion of second power terminal 75 Laminated portion 76a First end plate 76b Second end plate 78a Main bus bar 78a1 Expandable absorption section 78b Sub bus bar 78b1 Expandable absorption section 79 Power line 79a Power line protection tube 80 Plate assembly 81 Heat transfer plate 81a Flat plate section 81b Frame section 82a First end plate 82b Second end plate 83a First header section 83b Second header section 83c Third header part 83d Fourth header part 83e Fifth header part 83a1 First header part forming hole 83b1 Second header part forming hole 83c1 Third header part forming hole 83d1 Fourth header part forming hole 83e1 Fifth header part forming hole 83b2 2nd header part corresponding hole 83c2 3rd header part corresponding hole 83d2 4th header part corresponding hole 85 Meandering channel plate 85a Meandering channel 86 Water distribution plate 86a Main hole 86b Peripheral part 86c Sub-hole 87a First auxiliary plate 87b Second Auxiliary plate 87c 3rd auxiliary plate 87d 4th auxiliary plate 88 Heat transfer fin 89a 1st circulation hole 89b 2nd circulation hole 89c 3rd circulation hole 89d 4th circulation hole 89e 5th circulation hole 100 Fuel cell system Aa to Ac Air B1 1st bellows expansion joint B2 2nd bellows expansion joint B3 3rd bellows expansion joint B4 4th bellows expansion joint BP Branch pipe Bp1 Bellows expansion joint CV Curved section Ch Unit channel Ch1 Inclined flow Channel section Ch2 Turned channel section D1 Gas outlet E1, E2 Fuel intake port E3, E4 Air intake port Fg Flange Ga Raw fuel gas Gb Mixed gas Gc Reformed gas Gd Anode off gas Ge Cathode off gas Gf Raw fuel gas Gg Combustion gas La Raw fuel line Lb Mixed gas line Lc Anode fuel line Ld Anode off-gas line Ld1 Pipe Le Cathode air line Le1 Pipe Le2 Bypass route Lf Cathode off-gas line Lf1 Pipe Lg Combustion gas line Lg1 Pipe Lh Burner cooling air line Li Reform Quality water line Lj Starting air line Lw Condensed water recovery line Ma 1st distribution manifold Mb 2nd distribution manifold Mc 1st collection manifold Md 2nd collection manifold RG Reformed gas generator Sa Steam/water separation unit Sb Water level detector Sc Drain valve Wa Reformed water Wb Condensed water X1 1st box X1a 1st pedestal X2 2nd box X2a 2nd pedestal Za Heat radiation cylinder Zb Combustion gas pipe

Claims (6)

An evaporator for generating water vapor installed in a fuel cell system,
A plurality of heat transfer plates having front and back heat transfer surfaces that are substantially parallel to the vertical direction are stacked between a pair of opposing end plates, and the end plates and the heat transfer plates are joined and integrated. a plate assembly;
a serpentine flow path plate incorporated in each of the low temperature fluid flow paths formed on one of the heat transfer surfaces of the heat transfer plates;
heat transfer fins incorporated in each of the high temperature fluid flow paths formed on the other heat transfer surface side of the heat transfer plate;
The plate assembly includes a first header portion distributing water to each of the cold fluid flow paths, a second header portion collecting water vapor from each of the cold fluid flow paths, and a second header portion distributing water to each of the cold fluid flow paths. a third header section that distributes the heat source gas; and a fourth header section that collects the heat source gas from each of the high temperature fluid flow paths;
the first header part is formed on an upper part of the plate assembly;
the second header portion is formed at a lower portion of the plate assembly;
A fuel cell system characterized in that the meandering channel plate is continuously formed with a plurality of stages of unit channels each including an inclined channel section for allowing water to flow down and a folded channel section for reversing the fluid flow. evaporator. the third header part is formed at a lower part of the plate assembly;
The evaporator of claim 1, wherein the fourth header is formed on an upper portion of the plate assembly. The heat transfer plate has a first header forming hole, a second header forming hole, a third header forming hole, and a fourth header forming hole,
In each of the high-temperature fluid flow paths, a first auxiliary plate having a first flow hole for low-temperature fluid is disposed at a position corresponding to the first header-forming hole, and a first auxiliary plate having a first flow hole for low-temperature fluid is disposed in a position corresponding to the first header-forming hole. A second auxiliary plate having a second flow hole for low temperature fluid is arranged at a corresponding position,
In each of the low temperature fluid flow paths, a third auxiliary plate having a third flow hole for high temperature fluid is disposed at a position corresponding to the third header forming hole, and a third auxiliary plate having a third flow hole for high temperature fluid is disposed in a position corresponding to the third header forming hole. A fourth auxiliary plate having a fourth flow hole for high temperature fluid is arranged at a corresponding position,
The first header part is formed by connecting the first header part forming hole and the first communication hole,
The second header part is formed by connecting the second header part forming hole and the second communication hole,
The third header part is formed by connecting the third header part forming hole and the third communication hole,
The evaporator according to claim 1 or 2, wherein the fourth header section is formed by connecting the fourth header section forming hole and the fourth communication hole. The evaporator according to claim 3, wherein the third auxiliary plate and the fourth auxiliary plate are processed plates integrated with the meandering channel plate. A water distribution plate is disposed in each of the cryogenic fluid channels at a position corresponding to the first header forming hole,
The water distribution plate includes a main hole communicating with the first header forming hole and a peripheral edge surrounding the main hole,
The evaporator according to claim 3 or 4, wherein a sub-hole is formed in the peripheral portion, penetrating outward from an inner wall of the main hole. The plate assembly further includes a fifth header portion that distributes raw fuel gas to each of the cryogenic fluid flow paths,
The evaporator according to claim 1, wherein the fifth header section is formed near the first header section.