JP2023103838A - fuel cell device - Google Patents

Abstract

To provide a fuel cell device which can improve reforming performance of a reformer by increasing a temperature of reformed gas in a section outlet part of a reforming passage of the reformer.SOLUTION: An oxidant off gas discharged from a fuel cell stack 12 is circulated while being separated into first off gas and second off gas. A combustor 14 produces combustion gas by combustion of fuel gas contained in fuel off gas from the first off gas and the fuel off gas. Thereby, the temperature of the combustion gas supplied to a reformer 26 can be increased, compared to such a configuration that the total amount of the oxidant off gas is used in combustion of the fuel gas. In the other side heat medium passage 286, the ratio of a flow rate occupied by the combustion gas to the total flow rate of a heat medium is large, compared to a one side heat medium passage 285, and accordingly In the other side heat medium passage 286, the heat of the combustion gas is less likely to be consumed by the second off gas. As a result, the temperature of the combustion gas in the section outlet part 272 becomes high, which improves the reforming performance of the reformer 26.SELECTED DRAWING: Figure 2

Description

The present invention relates to a fuel cell device having a fuel cell.

As a fuel cell device of this type, for example, a fuel cell module disclosed in Patent Document 1 is known. The fuel cell module described in Patent Document 1 includes a fuel cell stack in which a plurality of flat fuel cells are stacked, an exhaust gas combustor, and a reformer.

The exhaust gas combustor of the fuel cell module of Patent Document 1 is supplied with the total amount of the fuel exhaust gas and the total amount of the oxidant exhaust gas discharged from the fuel cell stack. The exhaust gas combustor burns the fuel exhaust gas and the oxidant exhaust gas to generate combustion gas, and the combustion gas is supplied to the reformer. The fuel exhaust gas is also called fuel off-gas, and the oxidant exhaust gas is also called oxidant off-gas.

Further, the reformer is formed with a reforming passage into which the reformed gas containing the raw fuel flows. In the reformer, the reformed gas is heated by the combustion gas while flowing through the reforming passage, thereby reforming the raw fuel contained in the reformed gas into fuel gas. The fuel gas thus obtained is supplied from the reformer to the fuel cell stack.

JP 2016-1524 A

In a reformer for a fuel cell, in order to improve the reforming performance of reforming the raw fuel into fuel gas, the section exit part, which is the exit part of the catalyst arrangement section in which the reforming catalyst is arranged in the reforming passage, is required. It is most important to raise the temperature of the reformed gas at .

However, in the fuel cell module of Patent Document 1, the entire amount of the oxidant offgas is mixed with the fuel offgas in the exhaust gas combustor, and the mixed gas of the oxidant offgas and the fuel offgas is burned. Therefore, the temperature of the combustion gas generated in the exhaust gas combustor becomes lower than, for example, a configuration in which part of the oxidant off-gas is not used for combustion of the fuel off-gas.

Therefore, in the reformer included in the fuel cell module of Patent Document 1, the temperature of the reformed gas cannot be made sufficiently high at the section outlet of the reforming passage. That is, there remains room for improving the reforming performance of the reformer. As a result of detailed studies by the inventors, the above was found.

In view of the above points, the present invention provides a fuel cell apparatus capable of improving the reforming performance of the reformer by raising the temperature of the reformed gas at the section outlet of the reforming passage of the reformer. intended to

In order to achieve the above object, the fuel cell device according to claim 1 comprises:
a fuel cell (12) that generates electricity through an electrochemical reaction using a fuel gas and an oxidant gas;
A branching part (18) for dividing the oxidant off-gas (Ga) discharged from the fuel cell into a first off-gas (G1a), which is a part of the oxidant off-gas, and a second off-gas (G2a), which is the remainder. )and,
a combustor (14) for generating a combustion gas (Gc) by burning the fuel gas contained in the fuel off-gas from the first off-gas and the fuel off-gas (Gfa) discharged from the fuel cell;
A reforming passage (27) into which a reformed gas (Grf) containing raw fuel flows is formed, and the raw fuel contained in the reformed gas flowing through the reforming passage is converted into at least one of the combustion gas and the second off-gas. A reformer (26) that reforms into fuel gas by heating with a heat medium containing
A reforming catalyst (29) for reforming the raw fuel into fuel gas is arranged in the reforming passage, and the reformed gas flows from one side to the other side in the gas flow direction (Df). is provided,
The reforming passage has a section inlet (271) located on one side in the gas flow direction of the catalyst-arranged section, and a section outlet (272) located on the other side in the gas flow direction of the catalyst-arranged section. death,
In the reformer, one side heat medium passages (285, 285a, 285b) through which the heat medium flows are separated from the section inlet part with one heat transferable partition wall parts (301, 301a, 301b) interposed therebetween; The other side heat medium passage (286) through which the heat medium flows is separated from the section outlet with the other heat transferable partition wall (302) interposed therebetween, and
In the heat medium passage on the other side, the ratio of the flow rate of the combustion gas to the total flow rate of the heat medium is larger than that in the heat medium passage on the one side.

In this way, part of the oxidant off-gas discharged from the fuel cell is not used for combustion of the fuel gas in the combustor. The temperature of the combustion gases produced in the combustor can be increased to heat the raw gases.

In the other side heat medium passage, the ratio of the flow rate of the combustion gas to the total flow rate of the heat medium is larger than that in the one side heat medium passage. is difficult to be stolen by the second offgas.

As a result, the temperature of the reformed gas that absorbs heat from the heat medium containing the combustion gas in the heat medium passage on the other side and flows through the section outlet of the reforming passage can be increased compared to the configuration of Patent Document 1, for example. . As a result, it is possible to improve the reforming performance of the reformer and, by extension, to improve the power generation efficiency of the fuel cell device.

It should be noted that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and specific components etc. described in the embodiments described later.

1 is a block diagram showing a schematic configuration of a fuel cell system using a fuel cell device in a first embodiment; FIG. FIG. 2 is a cross-sectional view schematically showing the schematic configuration of a reformer included in the fuel cell device in the first embodiment; FIG. 3A is a cross-sectional view of the same reformer as in FIG. 2, and FIG. FIG. 4 is a diagram showing the relationship between the temperature of reformed gas flowing through a section outlet of a reforming passage and the reforming rate at the section outlet in the first embodiment; FIG. 3 is a cross-sectional view, corresponding to FIG. 2, schematically showing the schematic configuration of a reformer included in the fuel cell device in the second embodiment. FIG. 3 is a cross-sectional view, corresponding to FIG. 2 , schematically showing the schematic configuration of a reformer included in a fuel cell device in a third embodiment; FIG. 3 is a cross-sectional view that schematically shows the schematic configuration of a reformer included in a fuel cell device in a fourth embodiment, and corresponds to FIG. 2 ; FIG. 10 is a cross-sectional view schematically showing the schematic configuration of a reformer included in a fuel cell device in a fifth embodiment, corresponding to FIG. 2 ; FIG. 9 is a cross-sectional view that schematically shows the schematic configuration of a reformer included in a fuel cell device in a sixth embodiment, and corresponds to FIG. 8 ; FIG. 9 is a cross-sectional view schematically showing the schematic configuration of a reformer included in a fuel cell device in a seventh embodiment, corresponding to FIG. 8 ; FIG. 11 is a partial enlarged view showing an enlarged portion XI of FIG. 10; FIG. 10 is a cross-sectional view schematically showing the schematic configuration of a reformer included in a fuel cell device in an eighth embodiment, corresponding to FIG. 2 ;

Hereinafter, each embodiment will be described with reference to the drawings. In addition, in each of the following embodiments, the same or equivalent portions are denoted by the same reference numerals in the drawings.

(First embodiment)
As shown in FIG. 1 , the fuel cell device 10 of this embodiment constitutes a part of the fuel cell system 8 . The fuel cell system 8 includes a desulfurizer 71 and an exhaust heat recovery device 72 in addition to the fuel cell device 10 . The fuel cell device 10 includes a fuel cell stack 12, a combustor 14, a combustion gas channel 16, a branch portion 18, a first offgas channel 181, a second offgas channel 182, and a combustor introduction A flow path 22 , a fuel recycle flow path 24 , a reformer 26 , an evaporator 32 , an ejector 34 and an air preheater 36 are provided. For example, the fuel cell stack 12, the reformer 26, the combustor 14, and the plurality of flow paths 16, 18, 22, 24, etc. are modularized and integrated.

The fuel cell stack 12 generates electricity through an electrochemical reaction using fuel gas and oxidant gas. This fuel cell stack 12 corresponds to the fuel cell of the present disclosure. In this embodiment, a gas containing hydrogen gas and carbon monoxide produced by a steam reforming reaction in the reformer 26 is used as the fuel gas. Air is used as the oxidant gas. Electrical energy is generated by an electrochemical reaction between hydrogen in the fuel gas and oxygen in the oxidant gas.

The fuel cell stack 12, also called a cell stack, is an assembly of a plurality of fuel cells (not shown). Each fuel cell is a solid oxide fuel cell (that is, SOFC), in which a fuel electrode (that is, an anode) is formed on one side of a flat plate-shaped solid electrolyte, and It has a configuration in which an air electrode (that is, a cathode) is formed. Both the fuel electrode and the air electrode are porous bodies made of conductive ceramics. In the fuel cell stack 12, all the fuel cells are vertically stacked and electrically connected in series. The above SOFC is an abbreviation for "Solid Oxide Fuel Cell".

The fuel cell stack 12 uses the fuel gas and the oxidant gas to generate power, and the remaining fuel gas and oxidant gas that are not used for the power generation are discharged from the fuel cell stack 12 . That is, fuel off-gases Gfa and Gfb, which are exhaust gases containing fuel gas, and oxidant off-gas Ga, which is exhaust gases containing oxidant gas, are discharged from the fuel cell stack 12, respectively. In the present embodiment, air is used as the oxidizing gas, so the oxidizing off-gas Ga may also be referred to as air off-gas.

The branch part 18 constitutes a part of the distribution path of the oxidant off-gas Ga discharged from the fuel cell stack 12, and is connected to, for example, an outlet through which the oxidant off-gas Ga is discharged in the fuel cell stack 12. . In addition, the upstream end of the first off-gas channel 181 and the upstream end of the second off-gas channel 182 are respectively connected to the branch portion 18 .

The branching portion 18 splits the oxidant offgas Ga discharged from the fuel cell stack 12 into the first offgas channel 181 and the second offgas channel 182 . That is, the branching unit 18 divides the discharged oxidant offgas Ga into a first offgas G1a that is part of the oxidant offgas Ga and a second offgas G2a that is the remainder. The branching portion 18 causes the first offgas G1a to flow through the first offgas channel 181 and the second offgas G2a into the second offgas channel 182 .

The first offgas flow path 181 is a flow path that guides the first offgas G1a to the combustor 14 . The second offgas flow path 182 is a flow path that guides the second offgas G2a to the reformer 26 while bypassing the combustor 14 .

The fuel offgases Gfa and Gfb discharged from the fuel cell stack 12 are divided and distributed to the combustor introduction channel 22 and the fuel recycling channel 24 . The downstream end of the combustor introduction passage 22 is connected to the combustor 14, and the combustor introduction passage 22 guides the fuel offgas Gfa that has flowed into the combustor introduction passage 22 to the combustor 14. . On the other hand, the downstream end of the fuel recycle channel 24 is connected to the suction port 34b of the ejector 34, and the fuel recycle channel 24 passes the fuel off-gas Gfb flowing into the fuel recycle channel 24 to the ejector 34. It leads to the suction port 34b. Therefore, the fuel recycle channel 24 joins the fuel off-gas Gfb with the gas containing the raw fuel supplied to the reformer 26 .

The combustor 14 is supplied with a first off-gas G1a containing an oxidant gas through a first off-gas flow path 181, and supplied with a fuel off-gas Gfa containing fuel gas discharged from the fuel cell stack 12 through a combustor introduction flow path 22. be. Then, the combustor 14 generates high-temperature combustion gas Gc from the supplied first off-gas G1a and fuel off-gas Gfa by burning the fuel gas contained in the fuel off-gas Gfa. This combustion gas Gc has a higher temperature than the second offgas G2a flowing through the second offgas flow path 182 .

For example, in the combustor 14, a mixed gas of the fuel offgas Gfa and the first offgas G1a is ignited by an igniter (not shown). As a result, the fuel gas contained in the mixed gas is combusted, and the combustion produces high-temperature combustion gas Gc. The generated combustion gas Gc is supplied to the reformer 26 through the combustion gas passage 16 .

An upstream end of the combustion gas flow path 16 is connected to the combustor 14 and a downstream end of the combustion gas flow path 16 is connected to the reformer 26 . That is, the combustion gas channel 16 is a channel that guides the combustion gas Gc from the combustor 14 to the reformer 26 .

The reformer 26 produces fuel gas containing hydrogen by steam reforming. Specifically, the reformer 26 is supplied from the ejector 34 with a mixed gas of raw fuel and steam as a reformed gas Grf (see FIG. 2) to be reformed. The reformer 26 heats the reformed gas Grf with a heat medium containing the combustion gas Gc and the second offgas G2a, thereby reforming the raw fuel contained in the reformed gas Grf into fuel gas. do. The reformer 26 supplies the reformed gas Grf containing the reformed fuel gas to the fuel electrode of the fuel cell stack 12 . The raw fuel supplied to the reformer 26 is city gas, which is gas containing hydrocarbons (eg, methane).

The combustion gas Gc used to heat the reformed gas Grf in the reformer 26 and the second offgas G2a are mixed and discharged from the reformer 26 . The mixed exhaust gas containing the combustion gas Gc and the second offgas G2a discharged from the reformer 26 flows through the reformer 26, the air preheater 36, and the evaporator 32 in this order. It is used as a heat source in each of the evaporators 32 .

Further, the mixed exhaust gas containing the combustion gas Gc and the second offgas G2a that flowed out from the evaporator 32 is supplied to the exhaust heat recovery device 72 provided outside the fuel cell device 10 . The exhaust heat recovery device 72 recovers the heat of the supplied mixed exhaust gas. For example, the exhaust heat recovery device 72 heats the water by heat exchange between the mixed exhaust gas and the water to generate hot water for hot water supply.

Water is supplied to the evaporator 32 from outside the fuel cell system 8 . The evaporator 32 heat-exchanges the mixed exhaust gas containing the combustion gas Gc and the second off-gas G2a with the water supplied to the evaporator 32, heats the water by the heat exchange, and generates steam. That is, the evaporator 32 is a heat exchanger that exchanges heat between the mixed exhaust gas and water. The evaporator 32 causes the generated water vapor to flow out to a confluence section 37 forming part of the gas flow path between the evaporator 32 and the inlet 34 a of the ejector 34 .

City gas (that is, raw fuel) is supplied to the desulfurizer 71 from outside the fuel cell system 8 . The desulfurizer 71 removes the sulfur component contained in the supplied city gas. The desulfurizer 71 causes the city gas from which sulfur components have been removed to flow out to the confluence section 37 .

The ejector 34 mixes the mixed gas of raw fuel and steam with the fuel off-gas Gfb supplied from the fuel recycling passage 24 and supplies the mixture to the reformer 26 . The ejector 34 has an inlet 34a, a suction port 34b, and a discharge port 34c.

The inlet 34a of the ejector 34 is connected to a confluence portion 37 where the raw fuel, which is city gas, and steam join together. A suction port 34 b of the ejector 34 is connected to the downstream end of the fuel recycling channel 24 . A reformer 26 is connected to the discharge port 34c of the ejector 34 .

The ejector 34 sucks the fuel off-gas Gfb from the fuel recycling passage 24 by injecting a mixed gas of raw fuel and water vapor from a nozzle (not shown) inside the ejector 34, and uses the sucked fuel off-gas Gfb as the raw fuel. It is discharged together with a mixed gas with water vapor. A mixed gas of the discharged fuel off-gas Gfb, raw fuel, and water vapor is supplied to the reformer 26 from the discharge port 34 c of the ejector 34 .

Air is supplied to the air preheater 36 from outside the fuel cell system 8 . The air preheater 36 causes heat exchange between the mixed exhaust gas containing the combustion gas Gc and the second offgas G2a and the air supplied to the air preheater 36, and heats the air through the heat exchange. That is, the air preheater 36 is a heat exchanger that exchanges heat between the mixed exhaust gas and air. Air preheater 36 supplies the preheated air to the cathode of fuel cell stack 12 .

The reformer 26 is a device for reforming the raw fuel into fuel gas as described above. Specifically, as shown in FIG. A passageway 28 is formed. The reformer 26 has a reforming catalyst 29 and passage partition walls 30 .

The reforming catalyst 29 is a catalyst for reforming the raw fuel into fuel gas, and is arranged in the reforming passage 27 . For example, the reforming catalyst 29 is formed as a plurality of spherical or substantially spherical (in short, particulate) particulate matter, each of which is composed of a noble metal catalyst and a carrier. It is porous.

The reforming passage 27 is a flow passage through which the reformed gas Grf to be reformed flows from one side to the other side in the gas flow direction Df. An upstream end 27a of the reforming passage 27 (that is, one end in the gas flow direction Df) is connected to a discharge port 34c of the ejector 34 (see FIG. 1). Accordingly, the reformed gas Grf containing steam and raw fuel flows into the reforming passage 27 from one side in the gas flow direction Df. On the other hand, the downstream end portion 27b of the reforming passage 27 (that is, the end portion on the other side in the gas flow direction Df) passes the reformed gas Grf containing the reformed fuel gas from the reformer 26 to the fuel cell. It is connected to a channel that flows to the fuel electrode of the stack 12 .

Since the reforming catalyst 29 is arranged in the reforming passage 27 as described above, the catalyst arrangement section Sc in which the reforming catalyst 29 is arranged is provided. For example, the reforming catalyst 29 is filled in the reforming passage 27 in the catalyst arrangement section Sc. Since the reformed gas Grf flows through the reforming passage 27 from one side to the other side in the gas flow direction Df, the reformed gas Grf flows from one side to the other side in the gas flow direction Df also in the catalyst arrangement section Sc.

Further, the reforming passage 27 has a section entrance portion 271 and a section exit portion 272 . The section inlet portion 271 is an inlet portion of the catalyst arrangement section Sc, and is located on one side of the catalyst arrangement section Sc in the gas flow direction Df. The section outlet portion 272 is an outlet portion of the catalyst arrangement section Sc, and is located on the other side of the catalyst arrangement section Sc in the gas flow direction Df.

The connecting heat medium passage 28 is formed along the reforming passage 27 and is a flow passage through which the heat medium that heats the reformed gas Grf in the reforming passage 27 flows. The heat medium flowing through the connecting heat medium passage 28 is a fluid containing at least one of the combustion gas Gc and the second off-gas G2a.

The connecting heat medium passage 28 has a passage upstream end 281 located on the upstream side of the heat medium flow of the connecting heat medium passage 28 and a passage downstream end 282 of the connecting heat medium passage 28 located on the downstream side of the heat medium flow. have. In this embodiment, the heat medium flow upstream side of the connecting heat medium passage 28 is the other side in the gas flow direction Df, and the heat medium flow downstream side of the connection heat medium passage 28 is one side in the gas flow direction Df. Therefore, the heat medium flowing through the connecting heat medium passage 28 forms a counterflow that flows in the opposite direction to the reformed gas Grf flowing through the reforming passage 27 over the entire length of the reforming passage 27 .

A passage upstream end 281 of the connecting heat medium passage 28 is connected to the combustion gas passage 16 (see FIG. 1), and a passage downstream end 282 is connected to the air preheater 36 . Accordingly, the combustion gas Gc supplied to the reformer 26 from the combustion gas flow path 16 is introduced into the connecting heat medium passage 28 from the passage upstream end 281 and flows through the connecting heat medium passage 28 to the passage downstream end 282 . In addition, the second off-gas G2a is not introduced into the passage upstream end 281 of the connecting heat medium passage 28 .

The connecting heat medium passage 28 also has a passage middle portion 283 located between the passage upstream end 281 and the passage downstream end 282 . A part of the passage side wall 284 facing the passage middle portion 283 is formed with a middle opening 284 a that penetrates the passage side wall 284 and is connected to the passage middle portion 283 .

The intermediate opening 284a is connected to the second offgas flow path 182 (see FIG. 1). Therefore, the second offgas G2a supplied from the second offgas passage 182 to the reformer 26 is introduced into the connecting heat medium passage 28 from the passage middle portion 283 via the middle portion opening 284a and reaches the passage downstream end 282. It flows through the connecting heat medium passage 28 .

That is, in the section from the passage upstream end 281 to the passage midway portion 283 of the connecting heat medium passage 28, only the combustion gas Gc, out of the second offgas G2a and the combustion gas Gc, flows as the heat medium. The second off-gas G2a introduced into the connecting heat medium passage 28 mixes with the combustion gas Gc at the middle portion 283 of the passage. In the section from the passage middle portion 283 to the passage downstream end 282 of the connecting heat medium passage 28, a mixed gas of the second offgas G2a and the combustion gas Gc flows as a heat medium.

Since the passage partition wall 30 is interposed between the reforming passage 27 and the connecting heat medium passage 28 , the passage partition wall 30 separates the reforming passage 27 and the connecting heat medium passage 28 . The passage partition 30 is made of, for example, a thin metal plate with high thermal conductivity. The passage partition wall 30 is in contact with the reformed gas Grf flowing through the reforming passage 27 and the heat medium flowing through the connecting heat medium passage 28, respectively, and conducts heat between the reformed gas Grf and the heat medium.

For example, the passage partition wall 30 contacts the reformed gas Grf in the reforming passage 27 over the entire length of the reforming passage 27 and contacts the heat medium in the connecting heat medium passage 28 over the entire length of the connecting heat medium passage 28 . Therefore, the passage partition wall 30 allows heat exchange between the reformed gas Grf in the reforming passage 27 and the heat medium in the connecting heat medium passage 28 over the entire length of the reforming passage 27 .

Focusing on the section entrance portion 271 of the reforming passage 27 , the passage partition wall 30 includes one partition wall portion 301 facing the section entrance portion 271 . The connecting heat medium passage 28 includes a one side heat medium passage 285 separated from the section entrance portion 271 with the one partition wall portion 301 interposed therebetween. The passage downstream end 282 of the connecting heat medium passage 28 is also the downstream end of this one side heat medium passage 285 . The reformed gas Grf flowing through the section inlet portion 271 absorbs heat from the heat medium in the one-side heat medium passage 285 and is in a non-equilibrium state. The non-equilibrium state is a state in which even if the temperature of the reformed gas Grf is constant, the reforming rate Rrf at which the raw fuel is reformed into the fuel gas increases over time.

Note that the reforming rate Rrf is sometimes called a methane conversion rate. Then, the reforming rate Rrf is determined by setting Mi to be the amount of methane contained in the reformed gas Grf at the inlet of the flow passage for reforming, and the amount of methane contained in the reformed gas Grf at the outlet of the flow passage. It is obtained from the following formula F1, where the amount is Mo. The amount of methane may be, for example, the mass flow rate of methane or the number of moles of methane that flows per unit time. The unit of the reforming rate Rrf obtained from the following formula F1 is "%".
Rrf=(Mi−Mo)/Mi×100 (F1)

Focusing around the section outlet portion 272 of the reforming passage 27 , the passage partition wall 30 includes the other partition wall portion 302 facing the section outlet portion 272 . The connecting heat medium passage 28 includes the other side heat medium passage 286 separated from the section outlet portion 272 with the other side partition wall portion 302 interposed therebetween. The passage upstream end 281 of the connecting heat medium passage 28 is also the upstream end of this other side heat medium passage 286 . The reformed gas Grf flowing through the section outlet portion 272 absorbs heat from the heat medium in the other side heat medium passage 286 and is in an equilibrium state. The equilibrium state is a state in which the reforming rate Rrf is constant if the temperature of the reformed gas Grf is constant. However, since the temperature of the reformed gas Grf is rising at the section outlet 272, the reforming rate Rrf at the section outlet 272 is not constant.

As described above, the connecting heat medium passage 28 includes the one side heat medium passage 285 and the other side heat medium passage 286 . It is connected in series with the downstream side of the medium flow. The intermediate passage portion 283 is located between the one side heat medium passage 285 and the other side heat medium passage 286 of the connecting heat medium passages 28 .

Therefore, both the second off-gas G2a and the combustion gas Gc are introduced into the one-side heat medium passage 285 as heat medium that exchanges heat with the reformed gas Grf. On the other hand, the second off-gas G2a is not introduced into the other side heat medium passage 286, and the combustion gas Gc is introduced as a heat medium that exchanges heat with the reformed gas Grf.

As a result, the flow rate of the heat medium flowing through the one side heat medium passage 285 is greater than the flow rate of the heat medium flowing through the other side heat medium passage 286 . In the other side heat medium passage 286, the flow rate Rc of the combustion gas Gc to the total flow rate of the heat medium (that is, the combustion gas flow rate rate Rc) is larger than that in the one side heat medium passage 285. The combustion gas flow rate ratio Rc is obtained from the following formula F2, where Qt is the flow rate of the heat medium and Qc is the flow rate of the combustion gas Gc contained in the heat medium.
Rc=Qc/Qt (F2)

In this embodiment, the combustion gas flow rate Rc in the other side heat medium passage 286 is "Rc=1", and the combustion gas flow rate Rc in the one side heat medium passage 285 is "0<Rc<1". As a reminder, "flow rate" as used in the description of this embodiment means mass flow rate unless otherwise specified.

As indicated by the solid line Lc in FIG. 3B, in the connecting heat medium passage 28, the heat medium flows from the passage upstream end 281 to the passage downstream end 282 while dissipating heat to the reformed gas Grf. The temperature decreases as the downstream end 282 of the passage is approached. In this embodiment, the predetermined point P2a is determined in advance based on the relationship between the temperature change of the combustion gas Gc before being mixed with the second off-gas G2a and the temperature T2a of the second off-gas G2a introduced into the passage middle portion 283. , the middle passage portion 283 is located. In the description of the present embodiment, the temperature T2a of the second off-gas G2a introduced into the middle passage portion 283 is also referred to as the introduction second off-gas temperature T2a.

The above-described predetermined location P2a indicates an arrangement location where the intermediate passage portion 283 of the connecting heat medium passage 28 is arranged. Specifically, the predetermined point P2a is a point where the temperature of the heat medium that flows from the passage upstream end 281 to the connecting heat medium passage 28 and reaches the middle portion 283 of the passage falls to the introduction second offgas temperature T2a. The "temperature of the heat medium reaching the middle passage portion 283" referred to here is, in other words, the temperature of the combustion gas Gc immediately before being mixed with the second off-gas G2a at the middle passage portion 283. An arrow A2a in (b) of FIG. 3 indicates that the second offgas G2a flows into the connecting heat medium passage 28 .

Note that the relationship between the temperature of the combustion gas Gc in the connecting heat medium passage 28 and the position in the connecting heat medium passage 28 in the gas flow direction Df is experimentally obtained in advance. Further, the introduction second off-gas temperature T2a is, more specifically, the temperature of the second off-gas G2a immediately before it flows into the passage middle portion 283, and the introduction second off-gas temperature T2a is also experimentally determined in advance. Therefore, the predetermined location P2a where the intermediate passage portion 283 of the connecting heat medium passage 28 is arranged is experimentally set in advance.

Next, the flows of the reformed gas Grf, the combustion gas Gc, and the second off-gas G2a within the reformer 26 will be described with reference to FIGS. 2 and 3. FIG.

As shown in FIGS. 2 and 3 , the combustion gas Gc supplied to the reformer 26 has a higher temperature than the second offgas G2a supplied to the reformer 26 . The combustion gas Gc supplied to the reformer 26 from the combustion gas passage 16 (see FIG. 1) is introduced into the connecting heat medium passage 28 from the passage upstream end 281 . On the other hand, the second offgas G2a supplied to the reformer 26 from the second offgas flow path 182 (see FIG. 1) is introduced into the connecting heat medium passage 28 from the middle portion 283 of the passage and joins the combustion gas Gc. .

Therefore, in the section from the passage middle portion 283 of the connecting heat medium passage 28 to the passage downstream end 282, the heat medium flowing through the connecting heat medium passage 28 is a mixed gas of the combustion gas Gc and the second off-gas G2a. On the other hand, in the section from the passage upstream end 281 of the connecting heat medium passage 28 to the passage middle portion 283, the heat medium flowing through the connecting heat medium passage 28 did not contain the second off-gas G2a and contained the combustion gas Gc. become gas.

Further, in the reforming passage 27, the reformed gas Grf before being reformed is introduced into the upstream end 27a of the reforming passage 27, and the reformed gas Grf flows downstream from the upstream end 27a of the reforming passage 27. It flows through the reforming passage 27 up to the end 27b. Therefore, in the catalyst arrangement section Sc of the reforming passage 27 , the reformed gas Grf flows from the section inlet section 271 to the section outlet section 272 .

In the reforming passage 27, the reformed gas Grf exchanges heat with the heat medium flowing in the connecting heat medium passage 28 and flows while absorbing heat from the heat medium. Therefore, as indicated by the dashed-dotted line Lrf in FIG. 3B, the temperature of the reformed gas Grf increases toward the downstream side of the reforming passage 27 (ie, the other side in the gas flow direction Df). While the reformed gas Grf flows into the catalyst arrangement section Sc, the raw fuel contained in the reformed gas Grf is reformed into fuel gas by the steam reforming reaction. The reformed gas Grf after reforming flows out from the downstream end 27b of the reforming passage 27 and flows to the fuel electrode of the fuel cell stack 12 (see FIG. 1).

As described above, according to the present embodiment, as shown in FIGS. 1 and 2, the branching section 18 converts the oxidant offgas Ga discharged from the fuel cell stack 12 into The first off-gas G1a, which is the first off-gas G1a, and the second off-gas G2a, which is the remaining part, are separately flowed. Then, the combustor 14 generates combustion gas Gc from the first offgas G1a and the fuel offgas Gfa discharged from the fuel cell stack 12 by burning the fuel gas contained in the fuel offgas Gfa.

This allows the combustor 14 to heat the reformed gas Grf in the reformer 26, compared to a comparative configuration in which, for example, the entire amount of the oxidant off-gas Ga is used for combustion of the fuel gas in the combustor 14. It is possible to increase the temperature of the combustion gas Gc to be supplied.

In the other side heat medium passage 286, compared to the one side heat medium passage 285, the proportion of the flow rate of the combustion gas Gc to the total flow rate of the heat medium is large. The heat of the combustion gas Gc is less likely to be taken away by the second offgas G2a.

For example, assuming a comparative example in which the second off-gas G2a is introduced into the connecting heat medium passage 28 from the passage upstream end 281 instead of the passage middle portion 283, in the case of the comparative example, the temperature of the heat medium is as shown in FIG. b) changes as indicated by the dashed line L1c. That is, in the comparative example, since the second off-gas G2a having a lower temperature than the combustion gas Gc is mixed with the combustion gas Gc at the passage upstream end 281, the temperature of the combustion gas Gc after the mixing is the temperature indicated by the solid line Lc. Compared with the temperature of the combustion gas Gc in the embodiment, it is lowered as indicated by the dashed line L1c. In short, in the comparative example, the temperature of the heat medium in the other side heat medium passage 286 is lower than in the present embodiment.

Therefore, in the present embodiment, compared to the above comparative example in which the second off-gas G2a is introduced from the passage upstream end 281 into the connected heat medium passage 28, the heat medium in the other side heat medium passage 286 and the section outlet portion 272 can increase the temperature difference ΔT with the reformed gas Grf flowing through. As a result, the temperature of the reformed gas Grf that absorbs heat from the heat medium in the other side heat medium passage 286 and flows through the section outlet portion 272 of the reforming passage 27 can be made higher than in the comparative example.

As shown in FIG. 4, at the section outlet 272 of the reforming passage 27, the higher the temperature of the reformed gas Grf, the higher the reforming rate Rrf at which the raw fuel is reformed into the fuel gas. Therefore, the reforming performance of the reformer 26 can be improved, and the power generation efficiency of the fuel cell device 10 can be improved.

(1) Further, according to the present embodiment, as shown in FIG. 2, the second off-gas G2a is not introduced into the other side heat medium passage 286, and the combustion gas Gc exchanges heat with the reformed gas Grf. introduced as a heat carrier. Therefore, the temperature of the heat medium in the other side heat medium passage 286 decreases as indicated by the dashed line L1c in FIG. 3B due to the mixing of the second off-gas G2a with the combustion gas Gc. can be avoided. As a result, the temperature difference ΔT between the heat medium in the other side heat medium passage 286 and the reformed gas Grf flowing through the section outlet portion 272 is increased, and the reforming performance of the reformer 26 is improved. can.

(2) Further, according to the present embodiment, as shown in FIGS. 2 and 3, in the one-side heat medium passage 285, both the second off-gas G2a and the combustion gas Gc are mixed with the reformed gas Grf. It is introduced as a heat medium to be exchanged. The second off-gas G2a and the combustion gas Gc introduced into the one-side heat medium passage 285 are higher in temperature than the reformed gas Grf flowing through the section inlet portion 271 of the reforming passage 27 .

As a result, for example, compared to the case where only the combustion gas Gc is introduced into the one-side heat medium passage 285, the flow rate of the heat medium, which is the heat source that gives heat to the reformed gas Grf flowing through the section inlet portion 271, is reduced. can be increased. As a result, a large amount of heat can be applied to the reformed gas Grf flowing through the section entrance portion 271 .

Then, the amount of heat taken by the reformed gas Grf from the heat medium in the one-side heat medium passage 285 by the steam reforming reaction, which is the endothermic reaction at the section inlet 271, is sufficiently supplied to the reformed gas Grf. is possible. In addition, it is possible to effectively use the amount of heat possessed by the second offgas G2a for the steam reforming reaction at the section inlet portion 271 .

(3) Further, according to the present embodiment, the combustion gas Gc supplied from the combustion gas passage 16 to the reformer 26 is introduced from the passage upstream end 281 into the connecting heat medium passage 28, up to the connecting heat medium passage 28 . The second offgas G2a supplied to the reformer 26 from the second offgas flow path 182 is introduced into the connecting heat medium passage 28 from the middle portion 283 of the passage, and flows through the connecting heat medium passage 28 to the downstream end 282 of the passage. do.

Therefore, while avoiding the temperature drop of the combustion gas Gc in the other side heat medium passage 286 due to the introduction of the second off gas G2a into the other side heat medium passage 286, the heat quantity possessed by the second off gas G2a is reformed. It can be effectively used for the steam reforming reaction in passage 27 .

(4) Further, according to the present embodiment, the second off-gas G2a is introduced into the connecting heat medium passage 28 from the middle passage portion 283 . In the middle passage portion 283 of the connecting heat medium passage 28, the temperature of the heat medium flowing from the passage upstream end 281 to the middle passage portion 283 and reaching the middle passage portion 283 is reduced to the introduction second off-gas temperature T2a. It is located at point P2a.

Therefore, the second offgas G2a can be heat-exchanged for steam reforming in the reforming passage 27 without waste. Specifically, it suppresses the transfer of part of the heat of the combustion gas Gc to the second off-gas G2a, and prevents the temperature drop of the heat medium caused by the introduction of the second off-gas G2a into the connecting heat medium passage 28. can be done. As a result, heat loss can be reduced and the reforming performance of the reformer 26 can be efficiently improved.

(Second embodiment)
Next, a second embodiment will be described. In this embodiment, differences from the above-described first embodiment will be mainly described. Also, the same or equivalent parts as those of the above-described embodiment will be omitted or simplified. This also applies to the description of the embodiments that will be described later.

As shown in FIG. 5, in this embodiment, instead of the connecting heat medium passage 28 (see FIG. 2) of the first embodiment, a first heat medium passage 41 and a second heat medium passage 42 through which the heat medium flows. is formed in the reformer 26 . In this point, the present embodiment differs from the first embodiment.

Specifically, the first heat medium passage 41 and the second heat medium passage 42 are flow passages that are separated from each other. are spaced apart on one side of the

The first heat medium passage 41 has a passage upstream end 411 positioned on the heat medium flow upstream side of the first heat medium passage 41 and a passage downstream end of the first heat medium passage 41 positioned on the heat medium flow downstream side. 412. The passage downstream end 412 is located on the other side of the passage upstream end 411 in the gas flow direction Df. The entire first heat medium passage 41 is positioned on one side of the section outlet portion 272 of the reforming passage 27 in the gas flow direction Df.

A passage upstream end 411 of the first heat medium passage 41 is connected to the second offgas passage 182 (see FIG. 1), and a passage downstream end 412 is connected to the air preheater 36 . Therefore, the second offgas G2a supplied from the second offgas passage 182 to the reformer 26 is introduced into the first heat medium passage 41 from the passage upstream end 411 and reaches the passage downstream end 412 in the first heat medium passage 41. distributed to

Note that the combustion gas Gc is not introduced into the first heat medium passage 41 . That is, the heat medium that flows through the first heat medium passage 41 and releases heat to the reformed gas Grf contains the second offgas G2a but does not contain the combustion gas Gc.

The second heat medium passage 42 has a passage upstream end 421 positioned upstream of the heat medium flow of the second heat medium passage 42 and a passage downstream end 421 of the second heat medium passage 42 positioned downstream of the heat medium flow. 422. The passage downstream end 422 is positioned on the other side of the passage upstream end 421 in the gas flow direction Df. The entire second heat medium passage 42 is located on the other side of the section inlet portion 271 of the reforming passage 27 in the gas flow direction Df.

A passage upstream end 421 of the second heat medium passage 42 is connected to the combustion gas passage 16 (see FIG. 1), and a passage downstream end 422 is connected to the air preheater 36 . Therefore, the combustion gas Gc supplied from the combustion gas passage 16 to the reformer 26 is introduced into the second heat medium passage 42 from the passage upstream end 421 and flows through the second heat medium passage 42 to the passage downstream end 422. do.

Note that the second offgas G2a is not introduced into the second heat medium passage 42 . That is, the heat medium that flows through the second heat medium passage 42 and releases heat to the reformed gas Grf contains the combustion gas Gc, but does not contain the second off-gas G2a.

The reformer 26 of this embodiment has a first passage partition 43 and a second passage partition 44 instead of the passage partition 30 (see FIG. 2) of the first embodiment. The first passage partition wall 43 and the second passage partition wall 44 are connected to form one passage side wall facing the reforming passage 27 and extending in the gas flow direction Df.

The first passage partition 43 is arranged on one side of the second passage partition 44 in the gas flow direction Df. The first passage partition wall 43 is interposed between the first heat medium passage 41 and the reforming passage 27 to separate the first heat medium passage 41 and the reforming passage 27 . On the other hand, the second passage partition wall 44 is interposed between the second heat medium passage 42 and the reforming passage 27 to separate the second heat medium passage 42 and the reforming passage 27 .

Focusing on the section entrance portion 271 of the reforming passage 27 , the first passage partition wall 43 includes one partition wall portion 301 facing the section entrance portion 271 . The first heat medium passage 41 includes a one side heat medium passage 285 separated from the section entrance portion 271 with the one partition wall portion 301 interposed therebetween. The passage upstream end 411 of the first heat medium passage 41 is also the upstream end of the one side heat medium passage 285 .

Focusing on the area around the section outlet portion 272 of the reforming passage 27 , the second passage partition wall 44 includes the other partition wall portion 302 facing the section outlet portion 272 . The second heat medium passage 42 includes the other side heat medium passage 286 separated from the section outlet portion 272 with the other side partition wall portion 302 interposed therebetween. The passage downstream end 422 of the second heat medium passage 42 is also the downstream end of the other side heat medium passage 286 . In this embodiment, as in the first embodiment, the heat medium flowing through the other side heat medium passage 286 contains the combustion gas Gc but does not contain the second off-gas G2a. , the combustion gas flow rate ratio Rc is larger than that of the one-side heat medium passage 285 .

In this embodiment, both the second off-gas G2a flowing through the one-side heat medium passage 285 and the combustion gas Gc flowing through the other-side heat medium passage 286 are the same for the reformed gas Grf flowing through the reforming passage 27. It is a parallel flow flowing in the direction.

Except for what has been described above, this embodiment is the same as the first embodiment. In addition, in the present embodiment, it is possible to obtain the same effects as in the first embodiment, which are provided by the configuration common to that of the first embodiment.

(Third embodiment)
Next, a third embodiment will be described. In this embodiment, differences from the above-described first embodiment will be mainly described.

As shown in FIG. 6, in this embodiment, instead of the connecting heat medium passage 28 (see FIG. 2) of the first embodiment, a first heat medium passage 41 and a second heat medium passage 42 through which the heat medium flows. is formed in the reformer 26 . In this point, the present embodiment differs from the first embodiment.

Specifically, the first heat medium passage 41 and the second heat medium passage 42 are flow passages that are separated from each other. The first heat medium passage 41 is disposed on the opposite side of the second heat medium passage 42 across the reforming passage 27 in the passage alignment direction Dw perpendicular to the gas flow direction Df. That is, the first heat medium passage 41, the reforming passage 27, and the second heat medium passage 42 are arranged in the passage arrangement direction Dw in the order of the first heat medium passage 41, the reforming passage 27, and the second heat medium passage 42. are placed. The passage alignment direction Dw is also the width direction of the reforming passage 27, for example.

The first heat medium passage 41 has a passage upstream end 411 positioned on the heat medium flow upstream side of the first heat medium passage 41 and a passage downstream end of the first heat medium passage 41 positioned on the heat medium flow downstream side. 412. The passage downstream end 412 is located on the other side of the passage upstream end 411 in the gas flow direction Df. The entire first heat medium passage 41 is positioned on one side of the section outlet portion 272 of the reforming passage 27 in the gas flow direction Df.

A passage upstream end 411 of the first heat medium passage 41 is connected to the second offgas passage 182 (see FIG. 1), and a passage downstream end 412 is connected to the air preheater 36 . Therefore, the second offgas G2a supplied from the second offgas passage 182 to the reformer 26 is introduced into the first heat medium passage 41 from the passage upstream end 411 and reaches the passage downstream end 412 in the first heat medium passage 41. distributed to

Note that the combustion gas Gc is not introduced into the first heat medium passage 41 . That is, the heat medium that flows through the first heat medium passage 41 and releases heat to the reformed gas Grf contains the second offgas G2a but does not contain the combustion gas Gc.

The second heat medium passage 42 has a passage upstream end 421 positioned upstream of the heat medium flow of the second heat medium passage 42 and a passage downstream end 421 of the second heat medium passage 42 positioned downstream of the heat medium flow. 422. The passage downstream end 422 is located on one side of the passage upstream end 421 in the gas flow direction Df.

A passage upstream end 421 of the second heat medium passage 42 is connected to the combustion gas passage 16 (see FIG. 1), and a passage downstream end 422 is connected to the air preheater 36 . Therefore, the combustion gas Gc supplied from the combustion gas passage 16 to the reformer 26 is introduced into the second heat medium passage 42 from the passage upstream end 421 and flows through the second heat medium passage 42 to the passage downstream end 422. do.

Note that the second offgas G2a is not introduced into the second heat medium passage 42 . That is, the heat medium that flows through the second heat medium passage 42 and releases heat to the reformed gas Grf contains the combustion gas Gc, but does not contain the second off-gas G2a.

The reformer 26 of this embodiment has a first passage partition 43 and a second passage partition 44 instead of the passage partition 30 (see FIG. 2) of the first embodiment.

The first passage partition wall 43 is interposed between the first heat medium passage 41 and the reforming passage 27 to separate the first heat medium passage 41 and the reforming passage 27 . On the other hand, the second passage partition wall 44 is interposed between the second heat medium passage 42 and the reforming passage 27 to separate the second heat medium passage 42 and the reforming passage 27 .

The second passage partition wall 44 contacts the reformed gas Grf in the reforming passage 27 over the entire length of the reforming passage 27, and contacts the combustion gas Gc in the connecting heat medium passage 28 over the entire length of the connecting heat medium passage 28. do. Therefore, the second passage partition wall 44 allows heat exchange between the reformed gas Grf in the reforming passage 27 and the combustion gas Gc in the connecting heat medium passage 28 over the entire length of the reforming passage 27 .

Focusing on the section entrance portion 271 of the reforming passage 27, the first passage partition wall 43 includes a first partition wall portion 301a facing the section entrance portion 271, and the second passage partition wall 44 includes the section entrance portion 301a. 271 includes a second one partition wall portion 301b. In the present embodiment, the first one-side partition wall portion 301a and the second one-side partition wall portion 301b correspond to the one-side partition wall portion of the present disclosure.

The first heat medium passage 41 includes a first one-side heat medium passage 285a separated from the section inlet portion 271 with the first one-side partition wall portion 301a interposed therebetween. The passage upstream end 411 of the first heat medium passage 41 is also the upstream end of the first one side heat medium passage 285a.

In addition, the second heat medium passage 42 includes a second one-side heat medium passage 285b separated from the section entrance portion 271 with the second one-side partition wall portion 301b interposed therebetween. The passage downstream end 422 of the second heat medium passage 42 is also the downstream end of the second one side heat medium passage 285b.

In this embodiment, the entire first one-side heat medium passage 285a and the second one-side heat medium passage 285b correspond to the one-side heat medium passage of the present disclosure. Therefore, the combustion gas flow rate ratio Rc in the one-side heat medium passage of the present disclosure is such that the combustion gas Gc is the total flow rate of the heat medium in the entirety of the first one-side heat medium passage 285a and the second one-side heat medium passage 285b. It is calculated from the above formula F2. For example, if the flow rate of the second off-gas G2a flowing through the first one-side heat medium passage 285a and the flow rate of the combustion gas Gc flowing through the second one-side heat medium passage 285b are the same, the combustion gas flow rate ratio Rc is " Rc=0.5".

On the other hand, focusing on the area around the section outlet portion 272 of the reforming passage 27 , the second passage partition wall 44 includes the other partition wall portion 302 facing the section outlet portion 272 . The second heat medium passage 42 includes the other side heat medium passage 286 separated from the section outlet portion 272 with the other side partition wall portion 302 interposed therebetween. The passage upstream end 421 of the second heat medium passage 42 is also the upstream end of the other side heat medium passage 286 .

In this embodiment, as in the first embodiment, the heat medium flowing through the other side heat medium passage 286 contains the combustion gas Gc but does not contain the second off-gas G2a. Therefore, in the other side heat medium passage 286, the combustion gas flow rate ratio Rc is larger than that in the entirety of the first and second one side heat medium passages 285a and 285b.

In this embodiment, the second off-gas G2a flowing through the first heat medium passage 41 flows parallel to the reformed gas Grf flowing through the reforming passage 27 . On the other hand, the combustion gas Gc flowing through the second heat medium passage 42 is countercurrent to the reformed gas Grf flowing through the reforming passage 27 .

Except for what has been described above, this embodiment is the same as the first embodiment. In addition, in the present embodiment, it is possible to obtain the same effects as in the first embodiment, which are provided by the configuration common to that of the first embodiment.

(Fourth embodiment)
Next, a fourth embodiment will be described. In this embodiment, differences from the above-described first embodiment will be mainly described.

As shown in FIG. 7, the reformer 26 is formed with two connected heat medium passages 28 . The two connected heat medium passages 28 are arranged to form a pair with the reforming passage 27 interposed therebetween. That is, one of the pair of connected heat medium passages 28 is arranged on the opposite side of the other, with the reforming passage 27 interposed therebetween in the passage alignment direction Dw. For example, the pair of connected heat medium passages 28 has a shape that is symmetrical in the passage alignment direction Dw with the reforming passage 27 interposed therebetween.

Since the pair of connecting heat medium passages 28 are provided in this way, the reformer 26 has a pair of passage partition walls 30 interposed between the reforming passage 27 and the connecting heat medium passage 28 . That is, one of the pair of passage partition walls 30 is interposed between the reforming passage 27 and one of the pair of connecting heat medium passages 28, and the other of the pair of passage partition walls 30 is interposed between the reforming passage 27 and the pair of connecting heat medium passages. It intervenes between the other of the medium passages 28 .

In this embodiment, the passage upstream ends 281 of the pair of connected heat medium passages 28 are connected to the combustion gas passages 16 (see FIG. 1), and the passage downstream ends 282 are connected to the air preheater 36, respectively. Further, the intermediate openings 284a connected to the pair of connected heat medium passages 28 are respectively connected to the second offgas flow paths 182 (see FIG. 1). Accordingly, the combustion gas Gc supplied from the combustion gas flow path 16 to the reformer 26 is distributed to the pair of connecting heat medium passages 28, respectively. The second offgas G2a supplied from the second offgas flow path 182 to the reformer 26 is also distributed to the pair of connected heat medium passages 28, respectively.

Except for what has been described above, this embodiment is the same as the first embodiment. In addition, in the present embodiment, it is possible to obtain the same effects as in the first embodiment, which are provided by the configuration common to that of the first embodiment.

(Fifth embodiment)
Next, a fifth embodiment will be described. In this embodiment, differences from the above-described first embodiment will be mainly described.

As shown in FIG. 8, in the present embodiment, as in the first embodiment, the reforming passage 27 is arranged side by side with respect to the connecting heat medium passage 28 on one side in the passage arranging direction Dw with the passage partition wall 30 interposed therebetween. ing. However, in this embodiment, the shape of the passage partition 30 is different from that in the first embodiment.

In this embodiment, the reforming catalyst 29 is formed as a plurality of particulates as in the first embodiment, but the illustration of the reforming catalyst 29 is simplified in FIG. is represented. This simplification of illustration of the reforming catalyst 29 is the same in the later-described diagram corresponding to FIG.

Specifically, the passage partition wall 30 has a shape in which a portion of the passage partition wall 30 along the catalyst arrangement section Sc is shifted toward the other side of the passage arrangement direction Dw with a step. Therefore, the passage partition wall 30 has a one-side extending partition wall portion 303 extending from the one-side partition wall portion 301 to one side in the gas flow direction Df. In contrast, it is arranged shifted to one side in the passage alignment direction Dw. The passage partition wall 30 is formed so as to create a step in the passage alignment direction Dw between the one partition wall portion 301 and the one side extended partition wall portion 303 .

Further, the passage partition 30 has the other side extending partition wall portion 304 extending from the other partition wall portion 302 to the other side in the gas flow direction Df. In contrast, it is arranged shifted to one side in the passage alignment direction Dw. The passage partition wall 30 is formed so that a step in the passage alignment direction Dw is also generated between the other partition wall portion 302 and the other extended partition wall portion 304 .

One partition wall 301 has a reforming side wall surface 301e facing one side in the passage direction Dw and a heat medium side wall surface 301f facing the other side in the passage direction Dw. The reforming-side one wall surface 301 e faces the section inlet portion 271 of the reforming passage 27 , and the heat medium-side one wall surface 301 f faces the one-side heat medium passage 285 .

The other partition wall portion 302 has a reforming-side second wall surface 302e facing one side in the passage-arranged direction Dw and a heat-medium-side other wall surface 302f facing the other side in the passage-arranged direction Dw. The other reforming side wall surface 302 e faces the section outlet portion 272 of the reforming passage 27 , and the other heat medium side wall surface 302 f faces the other heat medium passage 286 .

On the other hand, the partition wall portion 302 has a wavy shape extending in the gas flow direction Df in a passage longitudinal section (for example, the cross section in FIG. 8) cut along a plane along both the gas flow direction Df and the passage arrangement direction Dw. formed. That is, both the reforming-side wall surface 302e and the heat-medium-side wall surface 302f are formed to have a corrugated shape in the passage vertical cross section.

The corrugated shape of the passage partition wall 30 is partially provided in the passage partition wall 30, and is provided biased toward the other side in the gas flow direction Df in the portion along the catalyst arrangement section Sc. A non-wavy portion, which is a portion of the passage partition wall 30 along the catalyst arrangement section Sc excluding the above-mentioned wavy portion, is formed in a flat plate shape along the gas flow direction Df. Since the one partition wall portion 301 is also included in this non-wavy portion, both the reforming side wall surface 301e and the heat medium side wall surface 301f are formed in a planar shape along the gas flow direction Df.

Due to such a difference in wall surface shape, the heat medium side wall surface 302f is formed to have a larger surface area per unit length in the gas flow direction Df than the heat medium side wall surface 301f. The reforming-side wall surface 302e is formed to have a larger surface area per unit length in the gas flow direction Df than the reforming-side wall surface 301e.

In the present embodiment, as shown in FIG. 8, a second offgas introduction passage 284b extending in the passage arrangement direction Dw is formed in the reformer 26 in place of the middle opening 284a (see FIG. 2) of the first embodiment. It is The second off-gas introduction passage 284b corresponds to a passage-like extension of the intermediate opening 284a of the first embodiment.

Therefore, the second offgas introduction passage 284b is connected to the second offgas flow path 182 (see FIG. 1), like the intermediate opening 284a of the first embodiment. Then, the second offgas G2a supplied from the second offgas passage 182 to the reformer 26 is introduced into the intermediate passage portion 283 of the connecting heat medium passage 28 via the second offgas introduction passage 284b.

That is, the second offgas introduction passage 284b of the present embodiment is connected to the connecting heat medium passage 28 at the middle passage portion 283, and the second offgas G2a flows toward the middle passage portion 283 in the second offgas introduction passage 284b. flow.

(1) As described above, according to the present embodiment, the heat medium side wall surface 302f has a larger surface area per unit length in the gas flow direction Df than the heat medium side wall surface 301f. formed. The reforming-side wall surface 302e is formed to have a larger surface area per unit length in the gas flow direction Df than the reforming-side wall surface 301e.

Therefore, while suppressing an increase in the flow resistance of the reforming passage 27 and the connecting heat medium passage 28, the reformed gas Grf from the heat medium is transferred from the heat medium to the reformed gas Grf at the section outlet portion 272, which is the most important part for enhancing the reforming performance of the reformer 26. It is possible to promote heat transfer to

Except for what has been described above, this embodiment is the same as the first embodiment. In addition, in the present embodiment, it is possible to obtain the same effects as in the first embodiment, which are provided by the configuration common to that of the first embodiment.

(Sixth embodiment)
Next, a sixth embodiment will be described. In this embodiment, differences from the fifth embodiment described above will be mainly described.

As shown in FIG. 9, the passage partition 30 of the present embodiment is not provided with the corrugated shape shown in FIG. In this embodiment, the entire portion of the passage partition wall 30 along the catalyst arrangement section Sc is formed in a flat plate shape along the gas flow direction Df.

Also, in this embodiment, the direction of the second off-gas introduction passage 284b is different from that in the fifth embodiment. Specifically, the second off-gas introduction passage 284b of the present embodiment is inclined with respect to the connecting heat medium passage 28 so as to be located on one side in the gas flow direction Df as it approaches the middle portion 283 of the passage. In other words, the second off-gas introduction passage 284 b is positioned on the forward side in the direction of flow of the heat medium toward the intermediate passage portion 283 in the connected heat medium passage 28 as it approaches the intermediate passage portion 283 . It is slanted with respect to the passageway 28 .

(1) Therefore, an increase in the pressure loss of the heat medium due to the confluence of the combustion gas Gc and the second off-gas G2a at the mid-passage portion 283 of the connecting heat medium passage 28 is suppressed, and the second off-gas G2a is smoothly transferred to the combustion gas Gc. It is possible to merge with Then, it is possible to assist the flow of the combustion gas Gc with the flow of the second off-gas G2a.

Except for what has been described above, this embodiment is the same as the fifth embodiment. In addition, in this embodiment, the same effects as in the fifth embodiment can be obtained from the configuration common to that of the fifth embodiment.

(Seventh embodiment)
Next, a seventh embodiment will be described. In this embodiment, differences from the fifth embodiment described above will be mainly described.

As shown in FIGS. 10 and 11, the passage partition wall 30 of this embodiment is not provided with the corrugated shape shown in FIG. Instead, in the present embodiment, the other partition wall portion 302 of the passage partition wall 30 includes a gradient partition wall portion 302g located on one side in the passage arrangement direction Dw toward the other side in the gas flow direction Df.

The gradient partition wall portion 302g is arranged, for example, in the other partition wall portion 302 so as to be biased toward the other side in the gas flow direction Df. That is, the sloped partition wall portion 302g is arranged at a portion where the other partition wall portion 302 forms a step with respect to the other extended partition wall portion 304 . The sloped partition wall portion 302g makes the step of the other partition wall portion 302 with respect to the other extended partition wall portion 304 gentler than when the sloped partition wall portion 302g is absent. The gradient partition wall portion 302g may be flat, but the gradient partition wall portion 302g of the present embodiment is curved so as to form a concave surface on the reforming passage 27 side.

The other side extended partition wall portion 304 extends from the sloped partition wall portion 302g to the other side in the gas flow direction Df. The other side extended bulkhead portion 304 corresponds to the extended bulkhead portion of the present disclosure.

In addition, a plurality of particles, which are the reforming catalyst 29, are in contact with the gradient partition wall portion 302g. For example, the gradient partition wall portion 302g has a reforming passage side wall surface 302h facing the reforming passage 27, and the curvature radius Rx of the reforming passage side wall surface 302h is 1/1 of the particle diameter Dc of the reforming catalyst 29. is much larger for a particle radius of 2. A gas flow direction length Lx occupied by the reforming passage side wall surface 302 h in the gas flow direction Df is significantly larger than the particle diameter Dc of the reforming catalyst 29 . Due to such a dimensional relationship, a plurality of particles, which are the reforming catalyst 29, come into contact with the gradient partition wall portion 302g.

(1) As described above, according to the present embodiment, the other partition wall portion 302 of the passage partition wall 30 includes the gradient partition wall portion 302g located on one side in the passage arrangement direction Dw toward the other side in the gas flow direction Df. there is The other side extended partition wall portion 304 extends from the sloped partition wall portion 302g to the other side in the gas flow direction Df. A plurality of particles, which are the reforming catalyst 29, are in contact with the gradient partition wall portion 302g.

Therefore, the contact between the gradient partition wall portion 302g and the reforming catalyst 29 facilitates the transfer of heat to the reforming catalyst 29 at the gradient partition wall portion 302g, which is a portion of the other partition wall portion 302 that most easily receives heat from the heat medium. It can contribute to the improvement of performance. Furthermore, compared to the case where there is no gradient partition wall portion 302g and there is a step between the other side extended partition wall portion 304 and the other partition wall portion 302, the pressure loss of the reformed gas Grf flowing through the reforming passage 27 and the connection heat medium It is possible to reduce the pressure loss of the heat medium flowing through the passage 28 .

Except for what has been described above, this embodiment is the same as the fifth embodiment. In addition, in this embodiment, the same effects as in the fifth embodiment can be obtained from the configuration common to that of the fifth embodiment.

(Eighth embodiment)
Next, an eighth embodiment will be described. In this embodiment, differences from the above-described first embodiment will be mainly described.

As shown in FIG. 12, in the present embodiment, the reforming catalyst 29 formed as a plurality of particulates is packed so as to be denser toward the other side in the gas flow direction Df in the catalyst arrangement section Sc. This embodiment differs from the first embodiment in this respect.

Specifically, the catalyst arrangement section Sc of the present embodiment includes one side section S1c and the other side section S2c arranged on the other side of the one side section S1c in the gas flow direction Df and connected to the one side section S1c. have. The density of the reforming catalyst 29 in each of the one-side section S1c and the other-side section S2c corresponds to the particle diameter Dc of the reforming catalyst 29 (see FIG. 11).

That is, the distribution of the particle diameters Dc of the reforming catalyst 29 packed in the one-side section S1c is biased toward the larger diameter side compared to the reforming catalyst 29 packed in the other-side section S2c. In short, the particle diameter Dc of the reforming catalyst 29 packed in the one-side section S1c is larger than the particle diameter Dc of the reforming catalyst 29 packed in the other-side section S2c. As a result, the reforming catalyst 29 is more densely packed in the other section S2c than in the one section S1c.

(1) As described above, according to the present embodiment, the reforming catalyst 29 is packed so as to be denser toward the other side in the gas flow direction Df in the catalyst arrangement section Sc. As a result, it is possible to adjust the residence time of the reformed gas Grf in the catalyst arrangement section Sc of the reforming passage 27, and at the same time, heat is generated on the side of the section outlet 272 where the reforming catalyst 29 is densely packed. Exchange performance can be improved.

Except for what has been described above, this embodiment is the same as the first embodiment. In addition, in the present embodiment, it is possible to obtain the same effects as in the first embodiment, which are provided by the configuration common to that of the first embodiment.

Although this embodiment is a modification based on the first embodiment, it is also possible to combine this embodiment with any of the above-described second to seventh embodiments.

(Other embodiments)
(1) In each of the above-described embodiments, as shown in FIG. 1, the fuel cell device 10 includes the fuel cell stack 12, which is an assembly of a plurality of fuel cells, but this is just an example. For example, the fuel cell device 10 may have a single fuel cell instead of the fuel cell stack 12 . In that case, the fuel cell corresponds to the fuel cell of the present disclosure.

(2) In the above-described first embodiment, as shown in FIG. 3, the predetermined portion P2a of the connecting heat medium passage 28 at which the intermediate passage portion 283 is arranged is experimentally determined in advance. The predetermined point P2a is a point where the temperature of the heat medium that flows from the passage upstream end 281 to the connecting heat medium passage 28 and reaches the middle portion 283 of the passage falls to the introduction second offgas temperature T2a. However, this is an example.

For example, the predetermined location P2a where the intermediate passage portion 283 is arranged (in other words, the predetermined location P2a where the second off-gas G2a is introduced in the connecting heat medium passage 28) is different from the location shown in FIG. It may be set as a position shifted to the downstream side of the flow. That is, the predetermined point P2a where the second off-gas G2a is introduced is a point where the temperature of the heat medium that flows from the passage upstream end 281 to the connecting heat medium passage 28 and reaches the passage middle portion 283 is equal to or lower than the introduced second off-gas temperature T2a. may be assumed.

(3) In the above-described first embodiment, as shown in FIG. 2, the entire amount of the second offgas G2a supplied from the second offgas flow path 182 to the reformer 26 passes through the middle opening 284a to the middle of the passage. Although it is introduced from the portion 283 into the connecting heat medium passage 28, this is an example. For example, a small amount of the second offgas G2a is separated from the second offgas G2a supplied to the reformer 26 from the second offgas passage 182, and the small amount of the second offgas G2a is separated from the passage upstream end of the connected heat medium passage 28. It can also be assumed that the heat is introduced from 281 into the connecting heat medium passage 28 .

(4) In the above-described first embodiment, as shown in FIG. 2, the heat medium flowing through the connecting heat medium passage 28 flows along the entire length of the reforming passage 27 into the reformed gas Grf flowing through the reforming passage 27. It is an example of a countercurrent flow. For example, the connecting heat medium passage 28 is formed in a shape different from that in FIG. There is no problem even if it is a cross flow flowing in a direction perpendicular to the flow of Grf.

(5) In each of the embodiments described above, for example, in FIG. 2, the gas flow direction Df is shown as a direction along a straight line, but this is an example. For example, the gas flow direction Df may be along a curved line.

(6) In the above-described first embodiment, as shown in FIG. 2, the second off-gas G2a is mixed with the combustion gas Gc from the passage middle portion 283 to the passage downstream end 282 of the connecting heat medium passage 28. However, it is not essential that the second off-gas G2a and the combustion gas Gc are mixed.

(7) In the eighth embodiment described above, as shown in FIG. 12, the density of the reforming catalysts 29 in the catalyst arrangement section Sc changes stepwise, but it may change continuously.

(8) In the eighth embodiment described above, as shown in FIG. 12, the reforming catalyst 29 is unevenly dense according to the particle diameter Dc of the reforming catalyst 29, but this is an example. The density of the reforming catalyst 29 may be caused by factors other than the particle diameter Dc of the reforming catalyst 29 (for example, the shape of the reforming catalyst 29).

(9) In each of the above-described embodiments, as shown in FIG. 1, the fuel cell device 10 has a includes an ejector 34, but this is an example. For example, the fuel cell device 10 may have a pump provided in the fuel recycling flow path 24 instead of the ejector 34 .

Alternatively, it is also assumed that the fuel cell device 10 is not provided with the fuel recycling passage 24 and the fuel cell device 10 is configured so that the fuel off-gas Gfb is not supplied to the reformer 26 .

(10) In each of the above-described embodiments, the fuel cell stack 12 shown in FIG. 1 has a structure in which a plurality of fuel cells using a flat plate-shaped fixed electrolyte are stacked, but other structures may be used. . In addition, solid oxide fuel cells are used as the fuel cells constituting the fuel cell stack 12, but this is just an example. As the fuel cells constituting the fuel cell stack 12, other fuel cells such as molten carbonate fuel cells (that is, MCFC) may be used. The above MCFC is an abbreviation for "Molten Carbonate Fuel Cell".

(11) It should be noted that the present invention is not limited to the above-described embodiments, and various modifications can be made. Moreover, the above-described embodiments are not unrelated to each other, and can be appropriately combined unless the combination is clearly impossible.

Further, in each of the above-described embodiments, it goes without saying that the elements constituting the embodiment are not necessarily essential, unless it is explicitly stated that they are essential, or they are clearly considered essential in principle. stomach. In addition, in each of the above-described embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the constituent elements of the embodiment are mentioned, when it is explicitly stated that they are particularly essential, and when they are clearly limited to a specific number in principle is not limited to that particular number. In addition, in each of the above-described embodiments, when referring to the material, shape, positional relationship, etc. of the constituent elements, unless otherwise specified or in principle limited to a specific material, shape, positional relationship, etc. , its material, shape, positional relationship, and the like.

10 fuel cell device 12 fuel cell stack (fuel cell)
14 Combustor 18 Branch 26 Reformer 27 Reforming passage 29 Reforming catalyst 285 One side heat medium passage 286 Other side heat medium passage Df Gas flow direction

Claims (10)

A fuel cell device,
a fuel cell (12) that generates electricity through an electrochemical reaction using a fuel gas and an oxidant gas;
A branch portion ( 18) and
a combustor (14) for generating a combustion gas (Gc) by burning the fuel gas contained in the fuel off-gas from the first off-gas and the fuel off-gas (Gfa) discharged from the fuel cell;
A reforming passage (27) into which a reformed gas (Grf) containing raw fuel flows is formed, and the raw fuel contained in the reformed gas flowing through the reforming passage is combined with the combustion gas and the second offgas. A reformer (26) that reforms the fuel gas by heating with a heat medium containing at least one of and supplies the reformed gas containing the fuel gas to the fuel cell,
A reforming catalyst (29) for reforming the raw fuel into the fuel gas is arranged in the reforming passage so that the reformed gas flows from one side to the other side in the gas flow direction (Df). A section (Sc) is provided,
The reforming passage has a section inlet (271) positioned on the one side in the gas flow direction of the catalyst arrangement section and a section outlet positioned on the other side in the gas flow direction of the catalyst arrangement section. a portion (272);
In the reformer, one side heat medium passages (285, 285a, 285b) through which the heat medium flows are separated from the section inlet portion with one heat transferable partition wall portions (301, 301a, 301b) interposed therebetween. ) and the other side heat medium passage (286), which is separated from the section outlet with the other heat transferable partition wall (302) interposed therebetween and through which the heat medium flows, are formed,
In the fuel cell device, the ratio of the flow rate of the combustion gas to the total flow rate of the heat medium is greater in the other side heat medium passage than in the one side heat medium passage. 2. The fuel cell device according to claim 1, wherein said second off-gas is not introduced into said other side heat medium passage, and said combustion gas is introduced as said heat medium. 3. The fuel cell device according to claim 1, wherein both said second off-gas and said combustion gas or said second off-gas is introduced as said heat medium into said one side heat medium passage. The one-side heat medium passage and the other-side heat medium passage form a connected heat-medium passage (28) in which the one-side heat-medium passage is connected to the other-side heat-medium passage on the downstream side of the heat medium flow,
The connecting heat medium passage has a passage upstream end (281) located on the upstream side of the heat medium flow of the connected heat medium passages, and a passage downstream end (282) of the connected heat medium passages located on the downstream side of the heat medium flow. ), and a passage middle portion (283) located between the one side heat medium passage and the other side heat medium passage of the connecting heat medium passage,
The combustion gas is introduced into the connecting heat medium passage from the upstream end of the passage and flows as the heat medium in the connecting heat medium passage to the downstream end of the passage,
4. The second off-gas according to any one of claims 1 to 3, wherein said second off-gas is introduced into said connecting heat medium passage from a middle portion of said passage and circulates as said heat medium in said connecting heat medium passage to said downstream end of said passage. fuel cell device. The reformer has a passage partition wall (30) that includes the one partition wall portion and the other partition wall portion and separates the reforming passage and the connecting heat medium passage,
The passage partition wall transfers heat between the reformed gas flowing through the reforming passage and the heat medium flowing through the connecting heat medium passage,
In the connecting heat medium passage, the heat medium flows while radiating heat to the reformed gas,
In the middle of the passage, the temperature (T2a) of the second off-gas introduced into the middle of the passage is equal to the temperature of the heat medium flowing from the upstream end of the passage into the connecting heat medium passage and reaching the middle of the passage. 5. The fuel cell device according to claim 4, located at a predetermined location (P2a) where: The reformer has a passage partition wall (30) that includes the one partition wall portion and the other partition wall portion and separates the reforming passage and the connecting heat medium passage,
The passage partition wall transfers heat between the reformed gas flowing through the reforming passage and the heat medium flowing through the connecting heat medium passage,
In the connecting heat medium passage, the heat medium flows while radiating heat to the reformed gas,
In the middle of the passage, the temperature (T2a) of the second off-gas introduced into the middle of the passage is equal to the temperature of the heat medium flowing from the upstream end of the passage into the connecting heat medium passage and reaching the middle of the passage. 5. The fuel cell device according to claim 4, located at a predetermined point (P2a) that descends to the The reforming catalyst is formed as a plurality of particulate matter,
The reformer has a passage partition wall (30) that includes the one partition wall portion and the other partition wall portion and separates the reforming passage and the connecting heat medium passage,
The reforming passage is arranged side by side with respect to the connecting heat medium passage on one side in the passage alignment direction (Dw) across the passage partition,
The passage partition transfers heat between the reformed gas flowing through the reforming passage and the heat medium flowing through the connecting heat medium passage,
The other partition wall portion includes a gradient partition wall portion (302g) positioned closer to the one side in the passage arrangement direction as the gas flow direction approaches the other side,
The passage partition wall is an extended partition wall portion (304) that extends from the gradient partition wall portion to the other side in the gas flow direction and is displaced from the other partition wall portion to the one side in the passage arrangement direction. has
5. The fuel cell apparatus according to claim 4, wherein said reforming catalyst is in contact with said gradient partition. 7. The reforming catalyst according to any one of claims 1 to 6, wherein the reforming catalyst is formed as a plurality of particles, and is packed so as to be denser toward the other side in the gas flow direction in the catalyst arrangement section. A fuel cell device as described. The reformer is formed with a second offgas introduction passage (284b) that is connected to the connecting heat medium passage in the middle of the passage so that the second offgas flows toward the middle of the passage,
The second off-gas introduction passage is arranged in the connecting heat medium passage so as to be located on the forward side in the flow direction of the heat medium toward the middle portion of the passage in the connecting heat medium passage as it approaches the middle portion of the passage. 8. A fuel cell device according to any one of claims 4 to 7, tilted with respect to. The one partition has a heat medium side one wall surface (301f) facing the one heat medium passage,
The other partition wall portion has a heat medium side other wall surface (302f) facing the other heat medium passage,
10. The heat medium side wall surface is formed to have a larger surface area per unit length in the gas flow direction than the heat medium side wall surface. The fuel cell device according to .

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