JP7379861B2 - fuel cell system - Google Patents

Description

The present invention relates to a fuel cell system equipped with a combustor in the off-gas line of the fuel cell.

Patent Document 1 relates to a fuel cell system equipped with a combustor in the off-gas line of the fuel cell, and heat exchangers are installed in the cathode supply line and the anode supply line, respectively, and the combustion gas generated in the combustor is transferred to these heat exchangers. It is disclosed that the combustion gas channels leading into the exchanger are formed parallel to each other. In Patent Document 1, the heat exchanger on the cathode side is configured as a means for preheating the air, and the heat exchanger on the anode side is configured as a means for preheating and reforming the fuel.

JP2008-277280A (Paragraphs 0009 and 0042, Figure 1)

The combustion gas at the outlet of the combustor does not have uniform temperature properties, for example, the temperature is uneven. According to the technology described in Patent Document 1, there are structural restrictions on the paths of combustion gas from the combustor to the heat exchangers on the cathode side and the anode side. For example, the length is limited, so the combustor It is difficult to sufficiently agitate the combustion gas exiting the combustion chamber and to eliminate temperature distribution before branching it to each heat exchanger. As a result, the combustion gas is branched while the temperature distribution remains, resulting in unevenness in the amount of heat recovered by heat exchange between the cathode side and the anode side. There is a concern that this will affect the operating efficiency of the entire system.

The present invention takes the above problems into consideration, and aims to provide a fuel cell system that can achieve higher operating efficiency as a whole system by homogenizing the temperature characteristics of combustion gas supplied to a heat exchanger. do.

In one embodiment of the present invention, a fuel cell, a combustor provided in an off-gas line of the fuel cell, and a cathode supply line of the fuel cell are provided with a cathode side configured to be able to operate using combustion gas generated in the combustor as a high-temperature fluid. A heat exchanger, an anode-side heat exchanger configured to be operable using combustion gas as a high-temperature fluid, and a combustor and each of the cathode-side and anode-side heat exchangers are connected to an anode supply line of the fuel cell, A combustion gas passage that guides combustion gas to each of the cathode side heat exchanger and the anode side heat exchanger, including a collecting section extending from the combustor and branching the combustion gas flowing through the collecting section toward each heat exchanger. a combustion gas passage having a branch part, and a combustion gas homogenizer that is provided upstream of the branch part with respect to the flow of the combustion gas and promotes homogenization of the temperature properties of the combustion gas toward the branch part; A fuel cell system is provided.

According to the present invention, the temperature properties of the combustion gas directed to the cathode side heat exchanger and the anode side heat exchanger through the branch portion are promoted to be homogenized, and the temperature characteristics of the combustion gas directed to each of the cathode side heat exchanger and the anode side heat exchanger are promoted to be uniform, and By making it possible to supply combustion gas with a suppressed property distribution, it is possible to suppress unevenness in the amount of heat recovered by heat exchange between the cathode side and the anode side, and to improve the operating efficiency of the entire system. On the other hand, since it is possible to promote homogenization of the property distribution of combustion gas, it is possible to shorten the combustion gas passage, and it is possible to promote simplification of the layout.

FIG. 1 is a schematic diagram showing the basic configuration of a fuel cell system according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of the homogenization device of the fuel cell system according to the embodiment. FIG. 3 is a schematic diagram showing another example of the homogenizing device for the fuel cell system according to the above embodiment. FIG. 4 is a schematic diagram showing still another example of the homogenizing device for the fuel cell system according to the above embodiment. FIG. 5 is a schematic diagram showing still another example of the homogenizing device for the fuel cell system according to the embodiment described above. FIG. 6 is a schematic diagram showing still another example of the homogenizing device for the fuel cell system according to the embodiment described above. FIG. 7 is a schematic diagram showing still another example of the homogenizing device for the fuel cell system according to the above embodiment. FIG. 8 is a schematic diagram showing still another example of the homogenizing device for the fuel cell system according to the embodiment described above. FIG. 9 is a schematic diagram showing still another example of the homogenizing device for the fuel cell system according to the embodiment. FIG. 10 is a schematic diagram showing the positional relationship of the combustor, the cathode heat exchanger, and the anode heat exchanger. FIG. 11 is a schematic diagram showing the relative positions of the combustor, cathode heat exchanger, and anode heat exchanger with respect to the fuel cell stack. FIG. 12 is a schematic diagram showing the basic configuration of a fuel cell system according to another embodiment of the present invention.

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

(Overall configuration of fuel cell system)
FIG. 1 shows the basic configuration of a fuel cell system S1 according to an embodiment of the present invention.

The fuel cell system (hereinafter referred to as "fuel cell system", sometimes simply referred to as "system") S1 according to the present embodiment can be installed in an electric vehicle, and is supplied to an electric motor for driving provided in the vehicle. generate electricity.

The fuel cell system S1 includes a fuel cell stack 1, an anode heat exchanger 2, a cathode heat exchanger 3, and a combustor 4 as main components related to this embodiment. In this embodiment, the term "heat exchanger" refers to any thermal device that is configured to receive a plurality of fluids having different temperatures and to transfer the amount of heat contained in the high-temperature fluid to the fluid to be heated. In this sense, "heat exchangers" include so-called heat exchange type heaters, in which the fluid to be heated is simply warmed without any chemical changes, as well as heaters that cause chemical changes in the fluid to be heated. This includes cases where the fluid after heating flows out as a fluid with a different composition from that at the time of inflow.

A fuel cell stack (hereinafter sometimes simply referred to as a "stack") 1 is constructed by stacking a plurality of fuel cells or fuel cell unit cells, and each fuel cell, which is a power generation source, is made of, for example, a solid oxide fuel cell. It is a fuel cell (SOFC). The fuel cell system S1 includes an anode gas supply line 11 and a cathode gas supply line 12, and the fuel cell stack 1 receives fuel gas through the anode gas supply line 11 and receives oxidation through the cathode gas supply line 12. Receives supply of agent gas. In this embodiment, the fuel gas is hydrogen and the oxidant gas is oxygen. The reaction related to power generation at the anode and cathode of a solid oxide fuel cell can be expressed by the following equation.
Anode pole: 2H ₂ +4O ^2- → 2H ₂ O+4e ^- …(1.1)
Cathode electrode: O ₂ +4e ^- → 2O ^2- ...(1.2)

Off-gas after the power generation reaction is discharged from the fuel cell stack 1 to an off-gas discharge line. FIG. 1 shows only the anode-side exhaust line (anode off-gas exhaust line) 13 extending from the fuel cell stack 1 among the anode-side and cathode-side off-gas exhaust lines. It goes without saying that a discharge line (cathode off-gas discharge line) is also provided for the cathode off-gas, and that this extends from the fuel cell stack 1.

The anode side heat exchanger 2 is interposed in the anode gas supply line 11, into which combustion gas generated in the combustor 4 described later is introduced, and operates using this as a high-temperature fluid. In this embodiment, the anode side heat exchanger 2 receives the supply of fuel gas and heats the fuel gas by heat exchange with combustion gas before supplying it to the fuel cell stack 1. In this sense, the anode side heat exchanger 2 according to this embodiment can also be called a fuel preheater. Fuel gas can be obtained by reforming raw fuel when equipped with a reformer that converts raw fuel into fuel gas, and when equipped with a fuel gas tank (not shown), it can be supplied from this tank. It is possible.

The cathode side heat exchanger 3 is interposed in the cathode gas supply line 12, into which the combustion gas generated in the combustor 4 is introduced, and operates using this as a high-temperature fluid. The cathode-side heat exchanger 3 receives the supply of oxidant gas and heats the oxidant gas by heat exchange with combustion gas before supplying it to the fuel cell stack 1 . Air from the atmosphere is taken into the cathode gas supply line 12 by an air compressor (not shown) and supplied to the fuel cell stack 1 via the cathode side heat exchanger 3, thereby supplying oxygen used for the power generation reaction to the cathode electrode. is possible. The cathode heat exchanger 3 according to this embodiment can be called an air preheater.

The combustor 4 is connected to an anode off-gas discharge line 13, receives anode off-gas discharged from the fuel cell stack 1 during normal system operation after warming up, and removes residual fuel (that is, residual hydrogen) in this off-gas. is combusted to generate combustion gas (hereinafter, the combustor 4 is particularly referred to as an "exhaust combustor"). In this embodiment, the exhaust combustor 4 is a catalytic type combustor that has a combustion section in which a catalyst for promoting combustion is supported. The exhaust combustor 4 is not limited to this, and a diffusion combustor may also be used. Furthermore, in this embodiment, a fuel supply pipe 14 is connected to the exhaust combustor 4, and fuel necessary for combustion is supplied to the exhaust combustor 4 via the fuel supply pipe 14. However, the present invention is not limited to this, and the cathode off-gas discharge line of this system S1 is connected to the exhaust combustor 4, and the cathode off-gas is introduced into the exhaust combustor 4. ) may be supplied.

The exhaust combustor 4 is connected to the anode heat exchanger 2 and the cathode heat exchanger 3 via a combustion gas passage 15. Combustion gas generated in the exhaust combustor 4 is supplied to the anode heat exchanger 2 and the cathode heat exchanger 3 through the combustion gas passage 15, respectively.

In this embodiment, the combustion gas is supplied from the exhaust combustor 4 to the anode side and cathode side heat exchangers 2 and 3 in parallel via the combustion gas passage 15. Specifically, the combustion gas passage 15 connects to a collecting section 151 extending from the exhaust combustor 4 to the downstream side of the collecting section 151, and directs the combustion gas flowing through the collecting section 151 toward each of the heat exchangers 2 and 3. It has branching parts 152 and 153 for branching. The branching parts 152 and 153 are bifurcated from the gathering part 151 at the branching point Pd, and include a first branching part 152 that connects the branching point Pd and the anode heat exchanger 2, and a first branching part 152 that connects the branching point Pd and the cathode heat exchanger 3. It has a second branch part 153 that connects. Based on such a configuration, after exiting the exhaust combustor 4, the combustion gas flows through the collecting section 151, and is divided into the first branch section 152 and the second branch section 153 at the branch point Pd, and the combustion gas flows through the first branch section 152. The heat exchanger 2 is supplied to the anode heat exchanger 2 through the heat exchanger 2, and the heat exchanger 3 is supplied to the cathode heat exchanger 3 through the second branch 153.

Here, the temperature of the combustion gas at the outlet of the exhaust combustor 4 is not uniform, for example, the temperature is uneven. In a fuel cell system according to a comparative example in which the heat exchangers 2 and 3 on the anode side and the cathode side are simply connected in parallel to the exhaust combustor 4, from the exhaust combustor 4 to each heat exchanger 2 and 3. Since there are structural constraints on the path of the combustion gas (for example, limited installation space and length), it is necessary to sufficiently stir the combustion gas until it reaches the branch point Pd to control the temperature distribution. It is difficult to resolve. As a result, the combustion gas is branched while the temperature distribution remains, and the amount of heat recovered by heat exchange between the anode side and the cathode side is uneven, which affects the operating efficiency of the entire system S1. There are concerns.

Therefore, in this embodiment, the temperature characteristics of the combustion gases supplied to each of the anode heat exchanger 2 and the cathode heat exchanger 3 are positively homogenized, thereby increasing the operating efficiency of the system S1 as a whole. is made possible.

Specifically, a means (homogenizer) 5 for promoting homogenization of the temperature properties of the combustion gas is installed in the gathering part 151 of the combustion gas passage 15, and the property distribution of the combustion gas, especially the unevenness in temperature, is corrected at the branch point. resolved or at least partially resolved by the time Pd is reached.

FIG. 2 shows a schematic configuration of the homogenization device 5 according to this embodiment. FIG. 2(a) shows a plan view of the combustion gas passage 15 seen from above in the vertical direction, and FIG. 2(b) shows the combustion gas passage 15 viewed from the direction indicated by arrow A in FIGS. The figure shows a side view (the same applies to FIGS. 3 and 6 to 9, which will be described later).

The homogenizer 5 is configured as a means for promoting homogenization of temperature properties by physical action, specifically, by hydrodynamic action, after combustion gas is generated. In this embodiment, it is particularly configured as a means for increasing the turbulence in the flow of combustion gas, and is specifically realized by the bent portion 51 of the conduit forming the combustion gas passage 15. The combustion gas that has flowed out of the exhaust combustor 4 (in FIGS. 2 to 9, the flow direction is indicated by an arrow Gc) is turbulent when passing through the bending portion 51, and the property distribution is resolved. The curvature of the conduit and the angle of deflection at the bent portion 51 can be appropriately set for the purpose of eliminating property distribution.

3 to 8 show a homogenizing device 5 according to a modification of this embodiment. The homogenizers 5 shown in FIGS. 3 to 8 are all configured as means for increasing turbulence in the flow of combustion gas, similar to that shown in FIG. 2.

FIG. 3 shows a schematic configuration of a homogenizing device 5 according to a first modification.

In a first variant, the homogenizer 5 is realized by a plurality of bends 52a to 52c formed in the conduit forming the combustion gas passage 15. In the first modified example, a case is shown in which the homogenizing device 5 is realized by three bent portions 52a to 52c, but the number of bent portions that the homogenizing device 5 can have is not limited to three, and may be changed as appropriate. It is possible to set. The turbulence of the combustion gas Gc flowing out of the exhaust combustor 4 increases when it passes through the bending portions 52a to 52c, and the property distribution is resolved.

FIG. 4 shows a schematic configuration of a homogenizing device 5 according to a second modification in a plan view of the combustion gas passage 15 viewed from above in the vertical direction.

In the second modification, the homogenizing device 5 is realized by a cross-sectional change part (the enlarged part 53a or the reduced part 53b) of the combustion gas passage 15 that expands or reduces the flow path cross-sectional area of the combustion gas flow. FIG. 4(a) shows an example in which the conduit forming the combustion gas passage 15 is provided with an enlarged portion 53a, and FIG. 4(b) shows an example in which the conduit is provided with a reduced portion 53b. There is. When the combustion gas Gc that has flown out of the exhaust combustor 4 passes through the enlarged portion 53a or the reduced portion 53b, turbulence is increased and the property distribution is resolved.

FIG. 5 shows a schematic configuration of a homogenizing device 5 according to a third modification in a plan view of the combustion gas passage 15 viewed from above in the vertical direction.

In the third modification, the homogenizing device 5 is realized by the cross-sectional changed portions (the enlarged portion 54a and the contracted portion 54b) of the combustion gas passage 15, as in the second modified example, but these cross-sectional changed portions 54a , 54b are provided in pairs. FIG. 5(a) shows an example in which a reduced portion 54b is provided on the upstream side with respect to the flow of combustion gas, and an enlarged portion 54a is provided on the downstream side with respect to the flow of combustion gas. An example is shown in which the enlarged part 54a is provided with a reduced part 54b on the downstream side. When the combustion gas Gc that has flown out of the exhaust combustor 4 passes through the enlarged portion 54a and the reduced portion 54b, turbulence is increased and the property distribution is resolved.

Here, in the example shown in FIG. 5A, since the flow at increased speed flows into the enlarged part 54a via the reduced part 54b, the turbulence is further increased on the downstream side of the enlarged part 54a. In the example shown in FIG. 5(b), a highly agitated flow flows meteredly into the contracted part 54b due to turbulence promoted through the enlarged part 54a, so that the property distribution is directed toward the branch point Pd. Combustion gas with suppressed combustion gas is stably supplied.

FIG. 6 shows a schematic configuration of a homogenizing device 5 according to a fourth modification.

In the second embodiment shown in FIG. 4 and the third modification shown in FIG. Change the cross-sectional area of the flow path before and after. Specifically, the homogenizing device 5 is realized by a bent portion 55 formed in a conduit forming the combustion gas passage 15, and the cross-sectional area of the conduit is enlarged before and after this bent portion 55. In the fourth modification, a case is shown in which the cross-sectional area of the flow path is expanded, but the present invention is not limited to this, and the cross-sectional area of the flow path may be reduced. When the combustion gas Gc that has flowed out of the exhaust combustor 4 passes through the bending portion 55, the turbulence increases due to both the change in flow direction and the change in the cross-sectional area of the flow path, resulting in a change in property distribution. will be resolved. When the cross-sectional area of the flow path is expanded, a relatively fast flow is formed toward the bend 55 on the upstream side of the bend 55. Then, this flow enters the bending portion 55 with appropriate force and collides with the opposing inner wall, thereby further promoting agitation of the combustion gas.

FIG. 7 shows a schematic configuration of a homogenizing device 5 according to a fifth modification.

In the fifth modification, the homogenizer 5 has a bent portion 56b formed in the conduit that forms the combustion gas passage 15, and the flow path is interrupted before and after this bent portion 56b, as in the fourth modification. Although the area is changed (specifically, reduced), cross-sectional change portions are provided other than the bent portion 56b. In other words, the homogenizing device 5 according to the fifth modification is realized by having a plurality of (in this embodiment, two) cross-sectional changing portions in addition to the bent portion 56b that also serves as the cross-sectional changing portion. . FIG. 8 shows an example in which the cross-sectional area of the flow path is reduced by the bent portion 56b, and enlarged portions 56a and 56c are provided on both the upstream and downstream sides of the flow of combustion gas. It is possible to set as appropriate whether the cross-sectional area of the flow path is expanded or narrowed by the bent portion 56b, or whether the cross-sectional area of the flow path is expanded or narrowed by the cross-sectional change portions 56a and 56c other than the bent portion 56b. The combustion gas Gc that has flowed out of the exhaust combustor 4 is affected by the cross-sectional changes 56a to 56c, and its turbulence is increased, and when it passes through the bent portion 56b, the turbulence is further increased, and the property distribution is further eliminated. is planned.

FIG. 8 shows a schematic configuration of a homogenizing device 5 according to a sixth modification.

In the sixth embodiment, the homogenizer 5 includes a combustion gas passage 15 in which the flow path center lines Cu and Cd defined for the upstream and downstream sides of the homogenizer 5 are shifted so that they do not intersect with each other and are non-parallel. This is realized by the offset portion 57a. Here, the "non-parallel state" refers to any state other than the parallel state, and includes the perpendicular state (FIG. 8(a)). Furthermore, "not intersecting" means that the channel center lines Cu and Cd, which are non-parallel to each other, are not in the same plane (FIG. 8(b)). In this embodiment, the offset portion 57a is formed by a bent portion 57a formed in a conduit forming the combustion gas passage 15. Specifically, the upstream conduit having a relatively small inner diameter and the downstream conduit having a larger inner diameter are connected at the bent portion 57b. An offset portion is formed by connecting the upstream conduit to the downstream conduit from the side so as to be offset from the straight line that defines the radial direction of the downstream conduit. When the combustion gas Gc that has flown out of the exhaust combustor 4 exits the upstream conduit and enters the bent portion 57a, the velocity component in the circumferential direction is promoted, thereby increasing the turbulence and further improving the property distribution. This will be resolved.

In FIG. 8, the connection point Pc between the upstream conduit and the downstream conduit (hereinafter simply referred to as the "conduit connection point") is offset vertically upward with respect to the downstream conduit, and the combustion gas is transferred downstream. An example is shown in which the combustion gas is introduced from the upper half area of the downstream side conduit, but the present invention is not limited to this. It is also possible to introduce from

FIG. 10 schematically shows the positional relationship of the anode heat exchanger 2, cathode heat exchanger 3, and combustor 4 according to the present embodiment in a side view from the direction of arrow A shown in FIG. The relative position of the homogenizer 5 with respect to these thermal devices 2 to 4 is also shown.

In this embodiment, the anode heat exchanger 2, the cathode heat exchanger 3, and the combustor 4 are arranged side by side in the horizontal direction H, and the homogenization device 5 is also provided as a whole for these thermal devices 2 to 4. is placed at a height equal to In FIG. 10(a), the anode heat exchanger 2, the cathode heat exchanger 3, and the combustor 4 are at the same height. In other words, the vertical centers of these thermal devices 2 to 4 are at the same height as each other. Although an example is shown where the heights are the same, there may be a vertical shift in the center position in relation to the actual installation space on the vehicle. At least a portion (preferably, the entirety) of the homogenizer 5 overlaps the combustor 4 in the horizontal direction H.

FIG. 10A shows an anode heat exchanger 2 and a combustor 4 provided on each side of the cathode heat exchanger 3 in the horizontal direction H. An example is shown in which the two overlap in the horizontal direction H. However, the positional relationship of the thermal devices 2 to 4 and the homogenizer 5 is not limited to this. As shown in FIG. The exchanger 3 may be placed on both sides, or the combustor 4 may be placed relative to the heat exchangers 2 and 3 on both sides, rather than just centered on the combustor 4, as shown in FIG. It is also possible to arrange it offset upward or downward. Even in such a case, it is preferable that the homogenizer 5 overlaps the combustor 4 at least partially, and in the example shown in FIG. A portion thereof overlaps the combustor 4 in the horizontal direction H. An example in which parts of the homogenizing devices 5 overlap can be realized, for example, by the embodiment shown in FIG. 3.

FIG. 11 shows the relative positions of the anode heat exchanger 2, cathode heat exchanger 3, and combustor 4 according to the present embodiment with respect to the fuel cell stack 1, as viewed from the side in the direction of arrow B shown in FIG. This is shown schematically by

In this embodiment, the anode heat exchanger 2, the cathode heat exchanger 3, and the combustor 4 are arranged in the horizontal direction H with respect to the fuel cell stack 1, and are generally arranged at the same height. In FIG. 11, the anode heat exchanger 2, cathode heat exchanger 3, and combustor 4 are located at the same height relative to the fuel cell stack 1. In other words, the vertical direction of these thermal devices 2 to 4 is An example is shown in which the center and the vertical center of the fuel cell stack 1 are at the same height, but there may be a vertical deviation in the center position in relation to the actual installation space on the vehicle. .

The positional relationship between the homogenizer 5 and the fuel cell stack 1 can be understood from the explanation regarding FIG.

(Explanation of effects)
The fuel cell system S1 according to this embodiment is configured as described above, and the actions and effects obtained by this embodiment will be described below.

First, the homogenization device 5 promotes homogenization of the temperature properties of the combustion gas flowing toward the anode heat exchanger 2 and the cathode heat exchanger 3 via the branch portions 152 and 153 of the combustion gas passage 15. It is possible to supply combustion gas with suppressed property distribution to the heat exchangers 2 and 3 regardless of configuration constraints such as layout, and the amount of heat recovered by heat exchange between the cathode side and the anode side is biased. This makes it possible to suppress the occurrence of problems and improve the operating efficiency of the entire system S1.

On the other hand, since homogenization of temperature properties can be actively promoted, the combustion gas passage 15 can be shortened and the layout can be simplified.

Second, by configuring the homogenizer 5 as a means for increasing the turbulence in the flow of combustion gas, it is possible to reliably promote homogenization of temperature properties and more reliably improve operating efficiency.

Thirdly, by providing the bent portions 51, 52a to 52c of the fuel gas passage 15 as the homogenizing device 5, it is possible to easily promote homogenization.

Fourthly, by providing the enlarged portions 53a, 54a or the reduced portions 53b, 54b of the combustion gas passage 15 as the homogenizer 5, it is possible to promote homogenization in the straight portion of the combustion gas passage 15. be.

Fifth, by providing the offset portion 57a of the combustion gas passage 15 as the homogenization device 5, it is possible to generate stirring over the entire cross section of the flow passage and promote homogenization more appropriately.

Sixth, by arranging the anode heat exchanger 2, the cathode heat exchanger 3, and the exhaust combustor 4 side by side in the horizontal direction H, the installation space with limited height can be used effectively. It is possible to efficiently install the thermal devices 2 to 4.

Furthermore, by arranging the anode side heat exchanger 2, cathode side heat exchanger 3, and combustor 4 side by side in the horizontal direction H with respect to the fuel cell stack 1, the fuel cell It is possible to efficiently install each element constituting the system S1.

According to the present embodiment, even when it is difficult to ensure a sufficient length of the combustion gas passage 15 from the viewpoint of ensuring homogeneity due to the restriction of the installation space, the combustion gas is stirred by the homogenizer 5. This makes it possible to promote homogenization of temperature properties, thereby making it possible to improve operating efficiency while overcoming constraints on installation space.

In the above description, a case has been described in which the flow turbulence is increased by changing the shape of the flow path (specifically, the direction of the flow and the cross-sectional area of the flow path). The flow turbulence is not limited to this, and even if the shape of the flow path is constant, it can be increased by installing a vortex generator or the like. In this sense, "increasing flow turbulence" includes not only increasing the already existing turbulence but also creating new turbulence.

Further, in the above description, a case has been described in which homogenization of temperature properties is promoted by increasing turbulence in the flow of combustion gas. Homogenization of temperature properties is not limited to this, but can also be promoted by swirling the flow of combustion gas. FIG. 9 shows an example in which swirlers or static mixers 58a and 58b are installed in the combustion gas passage 15. The homogenizer 5 is realized by a swirler or static mixer 58a, 58b. Swirlers or static mixers 58a, 58b impart a circumferential velocity component to the flow of combustion gases over the entire cross-section of the flow path. In this way, even by means of generating swirl, it is possible to suppress unevenness in the amount of heat recovery by eliminating property distribution, and to improve operating efficiency.

In the example shown in FIG. 9, two stages of swirlers 58a and 58b are provided in the direction of flow, but the number of stages of swirlers or static mixers 58a and 58b is not limited to this, and the number of stages may vary depending on the required homogeneity of the combustion gas. It is possible to set it as appropriate.

FIG. 12 shows the basic configuration of a fuel cell system S2 according to another embodiment of the present invention.

Similar to the embodiment described above, the fuel cell system S2 according to the present embodiment can also be installed in an electric vehicle and generate electric power to be supplied to the electric motor for driving provided in the vehicle. be.

In this embodiment, the anode gas supply line 11 is provided with a fuel evaporator 21 and a fuel reformer 22 . The fuel evaporator 21 and the fuel reformer 22 constitute the anode side heat exchanger 2 according to this embodiment. Thermal equipment provided in the system S2 other than the anode side heat exchanger 2 and its peripheral structure are the same as in the embodiment described above. Components that are the same as those in the previously described embodiment are given the same reference numerals as shown in FIG. 1, and their repeated explanation will be omitted.

In this embodiment, the anode side heat exchanger 2 receives a supply of raw fuel, which is a primary fuel, processes it, and converts it into a fuel gas used for a power generation reaction in a fuel cell. In this sense, the anode side heat exchanger 2 according to this embodiment can also be called a fuel processor. The raw fuel may be a mixture of oxygen-containing fuel and water, and is stored in a fuel tank (not shown) connected to the anode gas supply line 11. As the raw fuel applicable to this embodiment, a mixture of ethanol and water (that is, an aqueous ethanol solution) can be exemplified.

The fuel evaporator 21 receives an aqueous solution of ethanol, which is a raw fuel, from a fuel tank, and heats and evaporates it using combustion gas, which is a high-temperature fluid, to generate ethanol gas and water vapor.

The fuel reformer 22 is arranged downstream of the fuel evaporator 21 with respect to the flow of raw fuel, and generates hydrogen from ethanol in a gaseous state by steam reforming. Steam reforming can be expressed by the following equation. After the generated hydrogen exits the fuel reformer 22, it is supplied to the fuel cell stack 1 as fuel gas.
_C2H5OH + _3H2O → _6H2 + _2CO2 ...( ₂ )

In this way, even when the anode side heat exchanger 2 is configured by the fuel evaporator 21 and the fuel reformer 22, it is possible to obtain the same effects as described above. Specifically, the homogenizer 5 eliminates the property distribution of the combustion gas flowing through the gathering portion 151 of the combustion gas passage 15, thereby preventing unevenness in the amount of heat recovered by heat exchange between the cathode side and the anode side. This makes it possible to improve the operating efficiency of the entire system S2.

Furthermore, since it is possible to actively promote homogenization of temperature properties, it is possible to shorten the combustion gas passage 15 and promote simplification of the layout.

In the above description, a case has been described in which the combustion gas homogenization device 5 is installed in the gathering portion 151 of the combustion gas passage 15. However, the location where the homogenizer 5 is installed is not limited to this, and may be located downstream of the combustion section of the exhaust combustor 4 (in other words, the catalyst bed section on which the combustion promoting catalyst is supported). , can be appropriately selected within a range downstream of the branch point Pd of the combustion gas passage 15. It is not limited to the gathering part 151, but it is also possible to incorporate a swirler or a static mixer inside the casing of the exhaust combustor 4, for example.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of the application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiments. That's not the purpose. Various changes and modifications can be made to the above embodiments within the scope of the claims.

S1, S2... Fuel cell system 1... Fuel cell stack 2... Anode side heat exchanger 3... Cathode side heat exchanger 4... Exhaust combustor 5... Homogenizer 11... Anode gas supply line 12... Cathode gas supply line 13... Off-gas discharge line (anode off-gas discharge line)
14... Fuel supply pipe 15... Combustion gas passage 151... Collection part 152, 153... Branch part 21... Fuel evaporator 22... Fuel reformer Pd... Branch part

Claims (5)

fuel cell and
a combustor provided in the off-gas line of the fuel cell;
a cathode-side heat exchanger configured to be able to operate using combustion gas generated in the combustor as a high-temperature fluid in the cathode supply line of the fuel cell;
an anode-side heat exchanger configured to be operable using the combustion gas as a high-temperature fluid in the anode supply line of the fuel cell;
A combustion gas passage connecting the combustor and each of the cathode side and anode side heat exchangers, and guiding the combustion gas to each of the cathode side heat exchanger and the anode side heat exchanger, a combustion gas passage having a collecting part extending from the combustor, and a branching part that branches the combustion gas flowing through the collecting part toward each heat exchanger;
the combustion gas homogenizing device, which is provided upstream of the branch part with respect to the flow of the combustion gas and promotes homogenization of temperature properties of the combustion gas toward the branch part;
Equipped with
The homogenizing device is configured as a device that increases turbulence in the flow of the combustion gas,
The homogenizer has an offset portion of the combustion gas passage that shifts the flow path center lines of the flow defined on the upstream side and the downstream side thereof so that they do not intersect with each other and are non-parallel to each other.
fuel cell system. fuel cell and
a combustor provided in the off-gas line of the fuel cell;
a cathode-side heat exchanger configured to be able to operate using combustion gas generated in the combustor as a high-temperature fluid in the cathode supply line of the fuel cell;
an anode-side heat exchanger configured to be operable using the combustion gas as a high-temperature fluid in the anode supply line of the fuel cell;
A combustion gas passage connecting the combustor and each of the cathode side and anode side heat exchangers, and guiding the combustion gas to each of the cathode side heat exchanger and the anode side heat exchanger, a combustion gas passage having a collecting part extending from the combustor, and a branching part that branches the combustion gas flowing through the collecting part toward each heat exchanger;
the combustion gas homogenizing device, which is provided upstream of the branch part with respect to the flow of the combustion gas and promotes homogenization of temperature properties of the combustion gas toward the branch part;
Equipped with
The homogenizing device is configured as a device that generates swirl in the flow of the combustion gas,
fuel cell system. The cathode side heat exchanger and the anode side heat exchanger are arranged horizontally with respect to the combustor.
The fuel cell system according to any one of claims 1 to 2 . the combustor, the cathode heat exchanger, and the anode heat exchanger are arranged horizontally with respect to the fuel cell;
The fuel cell system according to claim 3 . The combustor has a combustion part on which a combustion promoting catalyst is supported,
The homogenizing device is provided downstream of the combustion section with respect to the flow of the combustion gas,
The fuel cell system according to any one of claims 1 to 4 .

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