JP7268468B2 - Combustor for fuel cell - Google Patents

Description

The present invention relates to combustors used in fuel cell systems.

As a combustor for a fuel cell, in Patent Document 1, an injector for injecting fuel is provided in the center, and a plate with a swirl blade is installed at a combustion air supply port provided on the outer periphery. A swirl supply of air is disclosed. Further, in the combustor of the above document, by specifying the distance to the heater and the number of swirls, it is disclosed that the flame ignited and burned in the heater is prevented from occurring in a so-called flashback, in which the flame is directed upstream from the heater. ing.

JP-A-2005-56636

However, in the configuration of the above document, although it is possible to narrow the region where the backflow occurs due to the generation of the swirl, there is a risk that the sprayed fuel rides on the backflow and adheres to the plate. In addition, there is a possibility that the fuel on the swirl may be blown off by the centrifugal force and adhere to the case wall surface. The greater the amount of the injected fuel that adheres to the plate or the case wall surface, that is, the greater the amount of wall flow, the greater the deviation of the air-fuel ratio of the air-fuel mixture composed of the fuel and the combustion gas from the set value. As a result, the combustion properties of the catalyst provided downstream of the heater deteriorate, and it takes time to start the combustor.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a combustor capable of suppressing the occurrence of wall flow.

A fuel cell combustor according to one aspect of the present invention includes a mixer plate disposed within a case and a fuel injector disposed centrally on the mixer plate. The fuel cell combustor includes a first swirler arranged on the mixer plate for generating a swirl flow in the combustion gas that has passed through the mixer plate, and a swirl flow generated by the first swirler for combustion. a second swirler that imparts a velocity component to the combustion gas in a direction that suppresses at least one of backflow of the gas and diffusion of the fuel due to centrifugal force , wherein the second swirler is radially inner than the first swirler of the mixer plate. and imparts a radially inward velocity component to the combustion gases passing through the second swirler .

According to the above aspect, the flow of combustion gas that has passed through the second swirler can suppress the generation of wall flow.

FIG. 1 is a diagram showing the basic configuration of a combustor. FIG. 2 is a perspective view of a mixer plate according to the first embodiment; FIG. FIG. 3 is an enlarged view of a tubular portion of the mixer plate according to the first embodiment. FIG. 4 is a diagram showing the flow of fuel and combustion gas within the combustor in the first embodiment. FIG. 5 is a perspective view of a mixer plate according to a second embodiment; FIG. 6 is a diagram showing the flow of fuel and combustion gas within the combustor in the second embodiment. FIG. 7 is a diagram showing the flow of fuel and combustion gas in the combustor in the third embodiment.

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

(First embodiment)
A first embodiment will be described with reference to FIGS. 1 to 4. FIG.

FIG. 1 is a diagram showing the basic configuration of a combustor 100 according to this embodiment. Arrows in the figure indicate the flow of fuel and combustion gas. "Upstream" and "downstream" in the following description respectively mean upstream and downstream in the direction of flow of fuel and combustion gas.

The combustor 100 burns a mixture of fuel and air as a combustion gas in a fuel cell system including solid oxide or polymer electrolyte fuel cells. The heat generated by this combustion is supplied to a fuel reformer or the like. Cathode off-gas discharged from the air electrode of the fuel cell may be used as the combustion gas.

The combustor 100 includes a catalyst 5 for burning fuel, a heater 4 for heating the air-fuel mixture supplied to the catalyst 5, and a cylindrical inner case 1A that houses the catalyst 5 and the heater 4. The combustor 100 further includes an injector 3 as a fuel injection section, a mixer plate 2, and an outer case 1B surrounding the outer circumference of the inner case 1A. In addition, the inner case 1A and the outer case 1B are collectively referred to as case 1 as well.

The outer case 1B forms a supply gas flow path 9 and a supply gas introduction portion 10 with the inner case 1A. A supply pipe 6 for combustion gas discharged from a compressor (not shown) is connected to the outer case 1B, and the combustion gas is supplied to the supply gas flow path 9 through this supply pipe 6. The combustion gas supplied to the supply gas flow path 9 flows into the supply gas introduction portion 10 defined by the outer case 1B and the mixer plate 2 while swirling along the outer circumference of the inner case 1A. Further, a combustion gas supply pipe 6 may be connected to the outer case 1B. This combustion gas is gas supplied from a compressor (not shown) and discharged through the stack.

The catalyst 5 is a combustion catalyst that burns the vaporized fuel gas by using the oxidant gas. The catalyst 5 and the heater 4 are arranged side by side so that the upstream end surface of the catalyst 5 and the downstream end surface of the heater 4 are in contact with each other. The catalyst 5 is a member in which a catalyst material is supported on the surface of a honeycomb structure as a carrier. The honeycomb structure is configured as a metallic cylindrical member, and platinum (Pt), palladium (Pd), or the like is used as a catalyst material supported on the honeycomb structure.

The heater 4 is an electric heater that evaporates fuel, and is used, for example, when the temperature of the catalyst 5 is lower than the temperature at which the fuel can be combusted. Therefore, the heater 4 is not used in the self-sustained operation state where the main body temperature of the combustor 100 is sufficiently high.

The heater 4 is composed of a honeycomb structure as a main body and electrode portions (not shown) provided on the periphery of the honeycomb structure. The honeycomb structure is configured as a metal cylindrical member and fixed to the inner case 1A. The heater 4 heats the honeycomb structure by energizing an electrode portion (not shown) provided so as to be exposed to the outside of the outer case 1B.

The injector 3 is an injector that injects fuel supplied via a fuel pump (not shown) at predetermined intervals.

The mixer plate 2 is a conical member provided on the upstream end surface of the inner case 1A. Injectors 3 are arranged in the center of the mixer plate 2 so that the fuel spray does not hit the mixer plate 2 directly. The reason why the injectors 3 and the mixer plate 2 are arranged in this way is that if the fuel spray adheres to the mixer plate 2 and causes wall flow, it becomes difficult to control the air-fuel ratio of the air-fuel mixture.

The mixer plate 2 also includes a first swirler 7 and a second swirler 8-1. Here, the first swirler 7 and the second swirler 8-1 will be explained.

2 is a perspective view of the mixer plate 2. FIG. FIG. 3 is an enlarged view of the portion of the mixer plate 2 provided with the second swirler 8-1.

The first swirler 7 is composed of a plurality of slits 7A penetrating the umbrella portion 2A of the mixer plate 2 and swirl vanes 7B provided in each slit 7A. The swirl blade 7B of the first swirler 7 is configured to give a swirl speed component in the same direction as the swirl speed component of the combustion gas swirling in the supply gas introduction part 10 .

The second swirler 8-1 is composed of a plurality of slits 8-1A passing through the cylindrical portion 2B in the center of the mixer plate 2 and swirl vanes 8-1B provided in each slit. The swirl vane 8-1B of the second swirler 8-1 is configured to cancel the swirl velocity component of the combustion gas swirling in the supply gas introduction section .

As shown in FIG. 2, the total opening area of the slits 7A of the first swirler 7 is significantly larger than the total opening area of the slits 8-1A of the second swirler 8-1. Therefore, most of the combustion gas that has flowed into the supply gas introduction portion 10 while maintaining the swirling state passes through the first swirler 7, and a part of the combustion gas passes through the second swirler 8-1.

The combustion gas that has passed through the first swirler 7 is further imparted with a swirling speed component by the first swirler 7, and advances in the direction of the heater 4 while being mixed with the fuel injected from the injector 3 while maintaining the swirling state.

On the other hand, the combustion gas that has passed through the second swirler 8-1 first accumulates inside the cylindrical portion 2B. flow in the direction of At this time, the fuel injected from the injector 3 passes through the central portion of the cylindrical portion 2B. Therefore, the combustion gas that has passed through the second swirler 8-1 flows along the outer circumference of the fuel.

Next, the effects of the first swirler 7 and the second swirler 8-1 configured as described above will be described with reference to FIG.

FIG. 4 is an enlarged view of a portion on the upstream side of heater 4 in FIG. Note that the first swirler 7 is omitted in FIG. In the figure, the dashed-dotted arrow indicates the swirling flow of the combustion gas that has passed through the first swirler 7 (hereinafter also referred to as the main gas flow 20), and the solid arrow indicates the flow of the combustion gas that has passed through the second swirler 8-1 ( hereinafter also referred to as a sub-gas flow 21-1), and the dashed arrow indicates a reverse flow (hereinafter also referred to as a reverse flow 22) caused by the generation of the swirling flow. Also, the dotted portion in the figure indicates the fuel spray.

Since the fuel is injected from linear injection holes by a multi-hole nozzle system under pressure, atomization of the fuel is facilitated, and the fuel spray spreads conically as shown in the figure. Then, the fuel is mixed with the combustion gas of the main gas flow 20 to form an air-fuel mixture, which is heated by the heater 4 and reacts with the catalyst 5 to generate heat.

Most of the downstream side of the mixer plate 2 is a swirling flow region due to the main gas flow 20, but a back flow 22 is generated between the fuel spray 23 and the main gas flow 20 having a strong flow in the swirling direction. If the backflow 22 occurs, part of the injected fuel may ride on the backflow 22 and reach the mixer plate 2, causing a so-called fuel wall flow. When the fuel wall flow occurs, the amount of fuel forming the air-fuel mixture decreases by the amount of the fuel wall flow, so the air-fuel ratio of the air-fuel mixture deviates from the set value for control.

However, in this embodiment, a sub-gas flow 21-1 traveling in the same direction as the fuel spray is formed between the fuel spray 23 and the main gas flow 20, and the sub-gas flow 21-1 and the reverse flow 22 collide. As a result, the flow of the reverse flow 22 is weakened, so the generation of the above-described fuel wall flow can be suppressed.

In some cases, the reverse flow 22 has a swirling velocity component that swirls around the fuel spray 23 . If it is found by simulation or the like that the reverse flow 22 has a swirl velocity component, the swirl vane 8-1B of the second swirler 8-1 is changed to generate a swirl velocity component in the direction opposite to the reverse flow 22 in the sub-gas flow 21-1. Configure to give.

Further, in the present embodiment, the case where the injector 3 injects the fuel radially and linearly has been described, but the fuel may be given a swirling speed component. In order to give a swirling velocity component to the fuel spray, a flow path for forming a swirling flow may be provided in the nozzle hole of the injector 3 . In this case, the sub-gas flow 21-1 is given a swirl velocity component in the direction opposite to the fuel. As a result, the flow of the backflow 22 can be weakened, and the flow of the fuel that tends to spread outward in the radial direction of the inner case 1A by swirling can also be suppressed. As a result, not only the fuel wall flow in the mixer plate 2 but also the fuel wall flow in the inner case 1A can be suppressed.

As described above, in this embodiment, the combustor 100 includes the mixer plate 2 arranged inside the case 1 and the injector 3 arranged in the center of the mixer plate 2 . The combustor 100 further includes a first swirler 7 arranged on the mixer plate 2 to generate a swirl flow in the combustion gas that has passed through the mixer plate 2, and a combustion gas generated by the swirl flow generated by the first swirler 7. and a second swirler 8-1 that gives the combustion gas a velocity component in the direction of suppressing the backflow 22 of the combustion gas. As a result, the amount of fuel that reaches the mixer plate 2 on the backflow 22 can be reduced by the flow of the combustion gas that has passed through the second swirler 8-1.

In the present embodiment, the second swirler 8-1 is arranged radially inward of the first swirler 7 of the mixer plate 2, and the combustion gas passing through the second swirler 8-1 has a radially inward velocity. give the ingredients. As a result, the combustion gas that has passed through the second swirler 8-1 gathers at the center of the mixer plate 2, and flows downstream along the outer circumference of the fuel stream spray due to the pressure difference between the center and the downstream side. flow. As a result, the flow of the combustion gas that has passed through the second swirler 8-1 faces the backflow 22, so that the amount of fuel that reaches the mixer plate 2 on the backflow 22 can be reduced as described above. .

In this embodiment, when the fuel injected from the injector 3 has a velocity component in the swirl direction, the second swirler 8-1 converts the swirl velocity component of the fuel in the direction opposite to the swirl direction to the second swirler 8-1. to the combustion gas passing through the As a result, the flow of the backflow 22 can be weakened, and the flow of the fuel that tends to spread outward in the radial direction of the inner case 1A by swirling can also be suppressed. As a result, not only the fuel wall flow in the mixer plate 2 but also the fuel wall flow in the inner case 1A can be suppressed.

In this embodiment, the injector 3 may be configured to give the fuel spray a swirl velocity component in the direction opposite to the swirl direction of the combustion gas passing through the first swirler 7 . As a result, backflow can be reduced, and the flow of fuel that tends to spread outward in the radial direction of the inner case 1A can also be suppressed.

(Second embodiment)
Next, a second embodiment will be described with reference to FIGS. 5 and 6. FIG.

FIG. 5 is a perspective view of the mixer plate 2 according to this embodiment.

The first swirler 7 is substantially the same as in the first embodiment. The second swirler 8-2 is also similar to the first embodiment in that it is composed of a plurality of slits 8-2A penetrating the mixer plate 2 and swirl vanes 8-2B provided in each slit 8-2A. However, the position to be provided is different from that of the first embodiment.

As shown in FIG. 5, the second swirler 8-2 of this embodiment is arranged on the outer peripheral side of the first swirler 7 in the mixer plate 2. As shown in FIG. The swirl vane 8-2B of the second swirler 8-2 eliminates the swirl velocity component of the combustion gas and gives the case 1 an axial velocity component.

The effects of the above configuration will be described with reference to FIG.

FIG. 6 is an enlarged view of a portion on the upstream side of the heater 4 in FIG. Note that the first swirler 7 is omitted in FIG. In the figure, the dashed-dotted arrow indicates the swirling flow of the combustion gas that has passed through the first swirler 7 (hereinafter also referred to as the main gas flow 20), and the solid arrow indicates the flow of the combustion gas that has passed through the second swirler 8-2 ( hereinafter also referred to as a sub-gas stream 21-2). The dashed arrows indicate the flow of fuel blown radially outward of the case 1 by the centrifugal force of the swirling main gas flow 20 (hereinafter also referred to as the radial flow 24). The dotted portion in the figure indicates the fuel spray.

By configuring the second swirler 8-2 as described above, the sub-gas flow 21-2 of the present embodiment flows outside the main gas flow 20 in the axial direction of the case 1. FIG.

If the amount of fuel reaching the wall surface of the inner case 1A increases due to the radial flow 24, a fuel wall flow may occur on the wall surface of the inner case 1A. However, in this embodiment, since the sub-gas flow 21-2 flows between the main gas flow 20 and the inner case 1A, the radial flow 24 can reduce the amount of fuel reaching the wall surface of the inner case 1A. . That is, it is possible to suppress the occurrence of fuel wall flow in the inner case 1A.

Note that the radial flow 24 may also be a three-dimensional flow having the same swirl velocity component as the main gas flow 20 . In this case, the swirl vane 8-2B of the second swirler 8-2 is configured to give the combustion gas a swirl velocity component opposite to the swirling direction of the radial flow 24. FIG. As a result, it is possible to reduce the swirling speed component of the fuel blown by the centrifugal force.

As described above, in this embodiment, the combustor 100 includes the mixer plate 2 arranged inside the case 1 and the injector 3 arranged in the center of the mixer plate 2 . The combustor 100 further includes a first swirler 7 arranged on the mixer plate 2 to generate a swirl flow in the combustion gas that has passed through the mixer plate 2, and a fuel flow generated by the swirl flow generated by the first swirler 7. and a second swirler 8-2 that imparts a velocity component in the direction of suppressing diffusion to the combustion gas. As a result, the amount of fuel reaching the inner case 1A due to the centrifugal force of the main gas flow 20 can be reduced by the flow of the combustion gas that has passed through the second swirler 8-1, so that the generation of fuel wall flow in the inner case 1A can be reduced. can be suppressed.

In this embodiment, the second swirler 8-2 is arranged radially outward of the first swirler 7 of the mixer plate 2, and the combustion gas passing through the second swirler 8-2 has a velocity in the axial direction of the case 1. give the ingredients. As a result, the combustion gas flow that has passed through the second swirler 8-2 intersects with the fuel blown by the centrifugal force of the main gas flow 20, thereby reducing the amount of fuel that reaches the inner case 1A. can be done. As a result, the occurrence of fuel wall flow in the inner case 1A can be suppressed.

In this embodiment, the second swirler 8-2 is arranged radially outside the first swirler 7 of the mixer plate 2, and when the radial flow 24 also has a swirl velocity component, the second swirler 8-2 gives the combustion gas that has passed through the first swirler 7 a swirl velocity component in the opposite direction to the combustion gas that has passed through the first swirler 7 . As a result, it is possible to reduce the swirling speed component of the fuel blown by the centrifugal force.

(Third Embodiment)
Next, a third embodiment will be described with reference to FIG.

FIG. 7 is an enlarged view of a portion on the upstream side of heater 4 in FIG. Note that the first swirler 7 is omitted in FIG. In the figure, the dashed-dotted arrow indicates the swirling flow of the combustion gas that has passed through the first swirler 7 (hereinafter also referred to as the main gas flow 20), and the solid arrow indicates the flow of the combustion gas that has passed through the second swirler 8-3 ( hereinafter also referred to as a sub-gas stream 21-3). The dashed arrows indicate the flow of fuel blown radially outward of the case 1 by the centrifugal force of the swirling main gas flow 20 (hereinafter also referred to as the radial flow 24). The dotted portion in the figure indicates the fuel spray.

Since the first swirler 7 is similar to that of the second embodiment, the description thereof is omitted.

The second swirler 8-3 is a plurality of through holes penetrating through the wall surface between the mixer plate 2 and the heater 4 in the inner case 1A. That is, in this embodiment, part of the combustion gas flowing through the supply gas flow path 9 is supplied inside the inner case 1A via the second swirler 8-3. The second swirler 8-3 is configured to impart a radially inward velocity component of the inner case 1A to the combustion gas passing through the through hole. The velocity component may be given only by the shape of the through-hole, or a swirl vane may be provided for giving the velocity component to each through-hole.

By configuring the second swirler 8-3 as described above, the sub-gas flow 21-3 flows radially inward from the wall surface of the inner case 1A. That is, the sub-gas flow 21-3 flows in the opposite direction to the radial flow 24. As shown in FIG. As a result, the amount of fuel blown by centrifugal force and adhering to the inner case 1A can be reduced.

Note that the radial flow 24 may also be a three-dimensional flow having the same swirl velocity component as the main gas flow 20 . In this case, the second swirler 8-3 is configured to give the combustion gas a swirling velocity component opposite to the swirling direction of the radial flow 24. FIG. As a result, it is possible to reduce the swirling speed component of the fuel blown by the centrifugal force.

As described above, in the present embodiment, the second swirler 8-3 is arranged on the wall surface of the inner case 1A between the mixer plate 2 and the heater 4 arranged downstream from the mixer plate 2. The radial velocity component of Case 1 is given to the combustion gases passing through -3. As a result, the amount of fuel blown by the centrifugal force on the main gas flow 20 can be reduced, and the generation of the fuel wall flow in the inner case 1A can be suppressed.

In the present embodiment, when the fuel blown radially outward by centrifugal force also has a swirling speed component, the second swirler 8-3 causes the combustion gas passing through the second swirler 8-3 to flow through the first swirler 7. A swirling velocity component in the direction opposite to that of the combustion gas that has passed through may be given. As a result, it is possible to reduce the swirling speed component of the fuel blown by the centrifugal force.

The second swirlers 8-1 to 8-3 described in the first to third embodiments may be combined as appropriate. For example, if both the second swirler 8-1 of the first embodiment and the second swirler 8-2 of the second embodiment are combined, both the fuel wall flow of the mixer plate 2 and the fuel wall flow of the inner case 1A can be reduced. Of course, the configuration may be such that all the second swirlers 8-1 to 8-3 of the first to third embodiments are provided.

It goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea described in the claims.

1A Inner case 1B Outer case 2 Mixer plate 3 Injector 4 Heater 5 Catalyst 6 Supply pipe 7 First swirler 8-1 to 8-3 Second swirler 9 Supply gas channel 10 Supply gas introduction part 100 Combustor

Claims (7)

a mixer plate positioned within the case;
a fuel injection part arranged in the center of the mixer plate;
In a fuel cell combustor comprising
a first swirler disposed on the mixer plate to generate a swirling flow in the combustion gas that has passed through the mixer plate;
a second swirler that imparts a velocity component to the combustion gas in a direction that suppresses at least one of backflow of the combustion gas and diffusion of fuel due to centrifugal force generated by the generation of the swirling flow by the first swirler; ,
with
The second swirler is arranged radially inward of the first swirler of the mixer plate, and imparts a radially inward velocity component to the combustion gas passing through the second swirler. Combustor for fuel cells. The fuel cell combustor according to claim 1 ,
When the fuel injected from the fuel injection part has a turning direction velocity component,
A said 2nd swirler is a combustor for fuel cells which gives a swirl velocity component of the direction opposite to the swirling direction of the said fuel to the said combustion gas which passes a said 2nd swirler. a mixer plate positioned within the case;
a fuel injection part arranged in the center of the mixer plate;
In a fuel cell combustor comprising
a first swirler disposed on the mixer plate to generate a swirling flow in the combustion gas that has passed through the mixer plate;
a second swirler that imparts a velocity component to the combustion gas in a direction that suppresses at least one of backflow of the combustion gas and diffusion of fuel due to centrifugal force generated by the generation of the swirling flow by the first swirler; ,
with
The second swirler is positioned radially outwardly of the first swirler of the mixer plate and directs the combustion gas passing through the second swirler opposite to the combustion gas passing through the first swirler. A fuel cell combustor that provides a directional swirl velocity component . a mixer plate positioned within the case;
a fuel injection part arranged in the center of the mixer plate;
In a fuel cell combustor comprising
a first swirler disposed on the mixer plate to generate a swirling flow in the combustion gas that has passed through the mixer plate;
a second swirler that imparts a velocity component to the combustion gas in a direction that suppresses at least one of backflow of the combustion gas and diffusion of fuel due to centrifugal force generated by the generation of the swirling flow by the first swirler; ,
with
The second swirler is arranged on a wall surface of the case between the mixer plate and a heater arranged downstream from the mixer plate, and the combustion gas passing through the second swirler is supplied with a diameter of the case. A fuel cell combustor that provides a directional velocity component . a mixer plate positioned within the case;
a fuel injection part arranged in the center of the mixer plate;
In a fuel cell combustor comprising
a first swirler disposed on the mixer plate to generate a swirling flow in the combustion gas that has passed through the mixer plate;
a second swirler that imparts a velocity component to the combustion gas in a direction that suppresses at least one of backflow of the combustion gas and diffusion of fuel due to centrifugal force generated by the generation of the swirling flow by the first swirler; ,
with
The second swirler is arranged on a wall surface of the case between the mixer plate and a heater arranged downstream from the mixer plate, and the combustion gas passing through the second swirler is supplied with the first swirler. A combustor for a fuel cell that gives a swirl velocity component in the opposite direction to the combustion gas that has passed through the combustor. In the fuel cell combustor according to any one of claims 3 to 5 ,
A combustor for a fuel cell, wherein the fuel injection section imparts a swirling speed component in a direction opposite to a swirling direction of the combustion gas passing through the first swirler to the fuel spray. a mixer plate positioned within the case;
a fuel injection part arranged in the center of the mixer plate;
In a fuel cell combustor comprising
a first swirler disposed on the mixer plate to generate a swirling flow in the combustion gas that has passed through the mixer plate;
a second swirler that imparts a velocity component to the combustion gas in a direction that suppresses at least one of backflow of the combustion gas and diffusion of fuel due to centrifugal force generated by the generation of the swirling flow by the first swirler; ,
with
The second swirler is arranged radially outward of the first swirler of the mixer plate, and imparts a velocity component in the axial direction of the case to the combustion gas passing through the second swirler,
A combustor for a fuel cell, wherein the fuel injection section imparts a swirling speed component in a direction opposite to a swirling direction of the combustion gas passing through the first swirler to the fuel spray.

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