JP2016062722A - Reforming unit for fuel cell, and fuel cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve power generation efficiency of a fuel cell stack.SOLUTION: A reforming unit for a fuel cell includes: an evaporation part for generating steam; a reforming part for reforming mixed gas of raw fuel and steam generated at the evaporation part to produce reformed gas and supplying the reformed gas to a fuel cell stack; a heat exchange part for heating up oxidant gas and supplying the heated oxidant gas to the fuel cell stack; and a combustion part for combusting the reformed gas and the oxidant gas discharged from the fuel cell stack and generating heat to be transferred to the evaporation part, the reforming part, the heat exchange part and the fuel cell stack. The evaporation part, the reforming part, and the heat exchange part are stacked, and the combustion part is disposed so as to be adjacent to the evaporation part, the reforming part, and the heat exchange part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fuel cell reforming unit (combustion unit, evaporation unit, reforming unit, and heat exchange unit) that constitutes a fuel cell module together with a fuel cell stack in which a plurality of solid oxide fuel cells (SOFCs) are stacked. The present invention also relates to a fuel cell module including such a fuel cell stack and a fuel cell reforming unit.

  A fuel cell module of a solid oxide fuel cell (SOFC) includes a fuel cell stack, which is an SOFC, and a fuel cell reforming unit (combustion unit, evaporation unit, reforming unit, and heat exchange unit).

  The combustion unit is a functional unit that burns the reformed gas that has not been used in the fuel cell stack, and transfers heat generated by the combustion to the evaporation unit, the reforming unit, the heat exchange unit, and the fuel cell stack. .

The evaporation unit is a functional unit that takes in water from outside, evaporates the water with heat received from the combustion unit to generate water vapor, and sends the water vapor to the reforming unit.
The reforming unit warms the reforming catalyst with the heat received from the combustion unit, and passes the mixed gas composed of raw fuel such as city gas and water vapor sent from the evaporation unit through the warmed catalyst. This is a functional unit that generates a quality gas and sends the reformed gas to the fuel cell stack.

The heat exchanging unit is a functional unit that raises the temperature of the oxidant gas with the heat received from the combustion unit and sends the heated oxidant gas to the fuel cell stack.
The fuel cell stack performs power generation by causing an electrochemical reaction between the reformed gas supplied from the reforming unit and the oxidant gas supplied from the heat exchange unit. At this time, the fuel cell stack needs to be kept at a high temperature, and power generation is hindered if the temperature is lowered by the supplied gas. For this reason, the fuel cell module is provided with a combustion section so that the reformed gas and the oxidant gas entering the fuel cell stack are warmed and the fuel cell stack is also warmed.

  This type of fuel cell module is disclosed in Patent Document 1, for example. In the fuel cell module disclosed in Patent Document 1, an evaporation unit and a reforming unit are disposed around a combustion unit, and a heat exchange unit is disposed further outside the evaporation unit and the reforming unit. .

JP 2014-78344 A

  However, in the fuel cell module disclosed in Patent Document 1, the heat exchange part is located outside the evaporation part and the reforming part as viewed from the combustion part. And the heat exchange part does not receive heat directly from a combustion part, but receives heat indirectly through the waste gas discharged | emitted from the combustion part. Specifically, the heat exchange unit receives heat from the exhaust gas from which heat has been removed by the evaporation unit and the reforming unit positioned between the combustion unit.

  Therefore, the temperature of heat received by the heat exchange unit from the combustion unit is considerably lower than that in the case of receiving heat directly from the combustion unit. As a result, the fuel cell stack receives the supply of the oxidant gas having a low temperature from the heat exchanging unit, and thus the power generation efficiency of the fuel cell stack is lowered by the lower temperature.

  An object of the present invention is to improve the power generation efficiency of a fuel cell stack.

  One aspect of the present invention is a fuel cell reforming unit for constituting a fuel cell module together with a fuel cell stack in which a plurality of fuel cells that generate electricity by an electrochemical reaction between a reformed gas and an oxidant gas are stacked, An evaporation section, a reforming section, a heat exchange section, and a combustion section are provided. The evaporation unit generates water vapor. The reforming unit reforms a mixed gas of raw fuel and water vapor generated in the evaporation unit to generate a reformed gas, and sends the reformed gas to the fuel cell stack. The heat exchange unit raises the temperature of the oxidant gas and sends the heated oxidant gas to the fuel cell stack. The combustion unit burns unreacted reformed gas discharged from the fuel cell stack, and generates heat to be transmitted to the evaporation unit, the reforming unit, the heat exchange unit, and the fuel cell stack. The evaporation section, the reforming section, and the heat exchange section are stacked, and the combustion section is disposed adjacent to the evaporation section, the reforming section, and the heat exchange section.

  According to such a configuration, the heat generated in the combustion section is directly transmitted to the heat exchange section as well as the evaporation section and the reforming section, and the oxidant gas is directly received from the combustion section. Is warmed. Therefore, the power generation efficiency of the fuel cell stack can be improved as compared with the conventional configuration in which the oxidant gas is warmed by heat indirectly received from the combustion unit.

Further, the evaporation unit, the reforming unit, and the heat exchange unit may be formed in a shape that surrounds the combustion unit in an annular shape.
According to such a configuration, since the bias of the amount of heat escaping from the combustion part is suppressed, it is possible to make it difficult for the fuel cell reforming unit to be damaged due to strain.

Moreover, the evaporation part may be arrange | positioned at the lowest stage.
The evaporating unit may receive heat at a temperature at which water can be evaporated at least, but the reforming unit requires a high temperature (for example, 800 degrees) for the reforming reaction. From the replacement part, it is necessary to send a reformed gas or an oxidant gas heated to a high temperature to the fuel cell stack. Since the temperature in the combustion part is higher as it goes upward, according to the configuration in which the evaporation part is arranged at the lowermost stage, the power generation efficiency of the fuel cell stack can be improved compared to the structure in which the evaporation part is arranged at other than the lowest stage. .

Moreover, the bottom part of the evaporation part may be formed in the shape which inclines upwards from the inner side which is the combustion part side to the outer side.
According to such a structure, since the water which entered the evaporation part flows toward a high temperature combustion part, the evaporation performance of water can be improved.

Further, the reforming section is arranged in the upper stage of the evaporation section, and the boundary section that forms the boundary between the reforming section and the evaporation section is formed in a shape that inclines upward from the inside which is the combustion section side to the outside. May be.
According to such a configuration, since the boundary between the reforming section and the evaporation section is inclined, more reforming catalyst that requires high heat can be brought closer to the high temperature side combustion section. Therefore, the reforming unit for a fuel cell can send a high-quality reformed gas to the fuel cell stack.

In addition, the combustion unit may emit exhaust gas in which the reformed gas and the oxidant gas are burned so as to spread over the entire lower surface of the fuel cell stack below the lower surface of the fuel cell stack.
According to such a configuration, the exhaust gas spread over the entire lower surface of the fuel cell stack is uniformly covered with a small temperature distribution bias, and the heat retention effect of the fuel cell stack is enhanced. Therefore, the power generation efficiency of the fuel cell stack can be improved.

  Also, a heat insulator covering the entire fuel cell stack, evaporation section, reforming section, heat exchange section, and combustion section, and a casing that surrounds the heat insulator so as to form an exhaust gas ventilation space between the heat insulator It is good also as a structure provided with these. And the discharge route which discharges | emits waste gas outside from the gas vent hole provided in the heat insulating body toward the discharge port provided in the housing | casing via exhaust gas ventilation space may be formed.

  According to such a configuration, the fuel cell stack is wrapped in the exhaust gas in the heat insulating material, so that a decrease in power generation efficiency is suppressed. Further, since the exhaust gas passes through the discharge route around the heat insulating material, the entire heat insulating material is also wrapped with the exhaust gas, so that the heat retaining effect is further enhanced. Accordingly, it is possible to suppress a decrease in the temperature of the fuel cell stack and to suppress a decrease in power generation efficiency.

FIG. 1A is a perspective view of a fuel cell module. FIG. 1B is a plan view of the fuel cell module. FIG. 2 is a perspective view when the housing of the fuel cell module is removed. About a heat insulating material, it has shown a mode that it cut | disconnected in the cross section of II-II of FIG. 3 (A). FIG. 3A is a cross-sectional view of the fuel cell module, and is a cross-sectional view of the IIIA-IIIA cross section of FIG. FIG. 3B is a cross-sectional view of the fuel cell module, and is a cross-sectional view of the IIIB-IIIB cross section of FIG.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 2, FIG. 3 (A) and FIG. 3 (B), the fuel cell module 1 of this embodiment has a plurality of stacked fuel cells that generate power by an electrochemical reaction between a reformed gas and an oxidant gas. A fuel cell stack 9 is provided inside.

  As shown in FIGS. 1A and 1B and the like, the fuel cell module 1 includes a housing 2 formed in a cylindrical shape as a whole. As shown in FIG. 3A and the like, a first supply pipe 312 and a second supply pipe 332 for introducing water or the like into the fuel cell module 1 penetrate through the side surface of the housing 2. And its end is outside.

  Further, as shown in FIG. 2 and the like, the fuel cell module 1 includes a main body 3 having a combustion part 30 and the like to be described later inside the housing 2. The fuel cell stack 9 is placed on the main body 3. The first supply pipe 312 and the second supply pipe 332 extend from the main body 3.

  As shown in FIGS. 3 (A) and 3 (B), the main body 3 is formed by bending or welding a sheet metal, for example, the combustion section 30, the evaporation section 31, the reforming section 32, and the heat exchange. Each functional part of the part 33 and the heat exhaust space 34 are assembled so as to be formed.

The combustion part 30 is formed in a cylindrical shape, and a plurality of exhaust gas holes 302 are formed on the upper side surface thereof.
The evaporation unit 31, the reforming unit 32, the heat exchanging unit 33, and the heat exhaust space 34 are formed in a shape that surrounds the combustion unit 30 in an annular shape. The wall surface (outer peripheral surface) of the combustion unit 30 is used as the inner wall surface on the combustion unit 30 side in the evaporation unit 31, the reforming unit 32, the heat exchange unit 33, and the heat exhaust space 34.

  Among these, the bottom part 319 of the evaporation part 31 and the boundary part 329 forming the boundary between the evaporation part 31 and the reforming part 32 are upward from the inner side which is the combustion part 30 side to the outer side which is the opposite side. It is formed in the shape which inclines toward. The boundary portion 329 has a plurality of passage holes 328 through which water vapor passes.

A first supply pipe 312 is connected to the evaporation unit 31. A mixture of city gas and water as raw fuel is supplied into the evaporation section 31 from the outside via the first supply pipe 312.
When the mixture is supplied to the evaporation unit 31, the mixture is warmed by the heat received from the combustion unit 30, and the water becomes water vapor. Then, the mixed gas in which the water becomes water vapor in the mixture is sent to the reforming unit 32 through the passage hole 328 provided in the boundary part 329.

  The reforming unit 32 is filled with a reforming catalyst (not shown). The reformer 32 is connected to a second pipe 321 (see FIG. 3B). The second pipe 321 is a pipe that supplies reformed gas to the fuel cell stack 9.

  When the mixed gas is supplied to the reforming unit 32 from the evaporation unit 31, the mixed gas is reformed by the catalyst activated by the heat received from the combustion unit 30, and a reformed gas is generated. This reformed gas is also warmed by the heat received from the combustion section 30.

The warmed reformed gas is supplied to the fuel cell stack 9 via the second pipe 321.
A third pipe 331 and a second supply pipe 332 are connected to the heat exchange unit 33 (see FIG. 3A). Air that is an oxidant gas is supplied into the heat exchanging unit 33 from the outside via the second supply pipe 332. The oxidant gas is heated by the heat received from the combustion unit 30 to be heated, and is supplied to the fuel cell stack 9 via the third pipe 331.

  A first pipe 301 is connected to the combustion unit 30 (see FIG. 3B). The first pipe 301 is a pipe that supplies the reformed gas that has not been used for power generation (unreacted) from the fuel cell stack 9 to the combustion unit 30. The reformed gas is supplied from the fuel cell stack 9 to the evaporation unit 31. Leads down.

  The combustion unit 30 mixes the reformed gas received from the fuel cell stack 9 via the first pipe 301 and the air taken from the outside, and burns it inside. The combustion unit 30 then discharges the exhaust gas generated by the combustion into the heat exhaust space 34 from the exhaust gas hole 302. The exhaust gas hole 302 is provided on the entire peripheral side surface of the portion located in the heat exhaust space 34 of the combustion unit 30.

  The heat exhaust space 34 forms an annular space having an upper surface parallel to the lower surface of the fuel cell stack 9. The heat exhaust space 34 is disposed at the uppermost portion of the main body 3, and the fuel cell stack 9 is placed on the upper portion of the main body 3.

  The heat insulator 4 is formed in a size that covers the entire assembly of the main body 3 and the fuel cell stack 9. The heat insulator 4 forms a heat insulating space 49 between the main body 3 and the fuel cell stack 9. A gas vent hole 40 is formed in the center of the upper surface of the heat insulator 4.

The housing 2 is formed in a size that can cover the heat insulator 4 surrounding the main body 3 and the fuel cell stack 9 so as to form an exhaust gas ventilation space 39 between the housing 2 and the heat insulator 4. Yes.
In addition, a discharge port 42 through which the exhaust gas ventilation space 39 opens to the external space is formed on the lower surface of the housing 2.

  By this exhaust gas ventilation space 39 and the exhaust port 42, there is an exhaust route for exhausting exhaust gas in the heat insulation space 49 between the housing 2 and the heat insulating body 4. Thus, a discharge route reaching the discharge port 42 is formed.

When the exhaust gas is discharged from the exhaust gas holes 302 of the combustion unit 30, the exhaust gas is released so as to spread over the entire lower surface of the fuel cell stack 9 below the lower surface of the fuel cell stack 9.
Thereafter, the exhaust gas discharged from the exhaust gas hole 302 is discharged from a heat discharge hole 341 provided in the heat discharge space 34 into a heat insulating space 49 surrounded by the heat insulating body 4.

  Therefore, the exhaust gas discharged from the exhaust gas holes 302 of the combustion unit 30 is discharged into the heat discharge space 34 and then discharged into the heat insulating space 49 of the heat insulating body 4 to be filled. And then discharged to the outside through the discharge port 42.

The fuel cell module 1 configured as described above has the following characteristic operational effects.
The fuel cell module 1 of the above embodiment uses the peripheral side surface of the combustion unit 30 as the inner wall surface of the evaporation unit 31, the reforming unit 32, and the heat exchange unit 33, and the evaporation unit 31, the reforming unit 32, And since the heat exchange part 33 is comprised, these are arrange | positioned adjacent to the combustion part 30. FIG.

Therefore, heat is directly transferred from the combustion unit 30 to the evaporation unit 31, the reforming unit 32, and the heat exchange unit 33 without being deprived of heat on the way.
Therefore, when this fuel cell module 1 is used, the oxidant gas is warmed by the heat directly received from the combustion unit 30, so that the fuel cell is compared with the conventional configuration in which the oxidant gas is warmed by heat lower than this temperature. The power generation efficiency of the stack 9 can be improved.

  Further, in the fuel cell module 1 of the above-described embodiment, the evaporation unit 31, the reforming unit 32, and the heat exchange unit 33 surround the combustion unit 30 in an annular shape. If there is a bias in the amount of heat that escapes from the combustion unit 30, the unit (fuel cell reforming unit) that constitutes the combustion unit 30, the evaporation unit 31, the reforming unit 32, and the heat exchange unit 33 is likely to be distorted. According to the configuration of the above embodiment, the amount of heat that escapes from the combustion unit 30 is less likely to be biased. Therefore, the possibility that the reforming unit for the fuel cell is damaged due to strain can be reduced.

Moreover, in the fuel cell module 1 of the said embodiment, the evaporation part 31 is arrange | positioned in the lowest stage.
The evaporation unit 31 may receive heat at a temperature at which water can be evaporated at least, but the reforming unit 32 needs a high temperature (for example, 800 degrees) for the reforming reaction. It is necessary to send a reformed gas and an oxidant gas heated to a high temperature from the fuel cell stack 9 to the fuel cell stack 9.

  Since the temperature in the combustion unit 30 is higher as it goes upward, according to the configuration in which the evaporation unit 31 is arranged at the lowermost stage, the power generation efficiency of the fuel cell stack 9 is improved compared to the configuration in which the evaporation unit 31 is arranged at other than the lowermost stage. Can be improved.

  Moreover, in the fuel cell module 1 of the said embodiment, the bottom part of the evaporation part 31 is formed in the shape which inclines while rising toward the outer side from the inner side which is the combustion part 30 side. Therefore, the water that has entered the evaporation section 31 flows toward the high-temperature combustion section 30 and the evaporation performance is improved.

  Further, in the fuel cell module 1 of the above-described embodiment, the reforming unit 32 is disposed on the upper stage of the evaporation unit 31, and the boundary portion 329 that forms the boundary between the evaporation unit 31 and the reforming unit 32 is the combustion unit 30 side. It is formed in a shape that inclines while rising from the inside to the outside.

  As described above, since the boundary portion 329 between the evaporation portion 31 and the reforming portion 32 is inclined, it is possible to bring more reforming catalysts that require high heat to be activated closer to the high-temperature combustion portion 30. it can.

Therefore, the fuel cell module 1 can send high quality reformed gas to the fuel cell stack 9.
The fuel cell module 1 of the above embodiment includes the housing 2 that can cover the entire fuel cell stack 9, the evaporation unit 31, the reforming unit 32, the heat exchange unit 33, and the combustion unit 30. The combustion unit 30 emits exhaust gas under the lower surface of the fuel cell stack 9.

  The fuel cell stack 9 is heated by the combustion unit 30 through the top surface (the top surface of the main body 3) that forms the heat exhaust space 34. However, for example, when the temperature distribution around the fuel cell stack 9 is biased, the temperature distribution of the fuel cell stack 9 may be biased to correspond to the bias.

  Therefore, according to the configuration in which the exhaust gas is discharged so as to spread over the entire lower surface of the fuel cell stack 9 below the lower surface of the fuel cell stack 9 as in the above-described embodiment, the fuel cell stack 9 is generated in the housing 2 by the exhaust gas. The whole is evenly covered with a small temperature distribution bias, and the temperature of the fuel cell stack 9 is maintained.

Therefore, this fuel cell module 1 can further improve the power generation efficiency of the fuel cell stack 9.
In the fuel cell module 1 of the above embodiment, the fuel cell stack 9, the evaporation unit 31, the reforming unit 32, the heat exchange unit 33, and the entire combustion unit 30 are covered with the heat insulator 4. And the housing | casing 2 has enclosed the heat insulating body 4 so that the exhaust gas ventilation space 39 may be formed between the heat insulating bodies 4. FIG.

  As a result, the inside of the heat insulating space 49 surrounded by the heat insulating body 4 from the gas vent hole 40 provided at the top of the heat insulating body 4 through the exhaust gas ventilation space 39 toward the discharge port 42 provided at the bottom of the housing 2. A discharge route for discharging the exhaust gas to the outside is formed.

According to such a configuration, the fuel cell stack 9 is wrapped in the exhaust gas in the heat insulator 4, the temperature of the fuel cell stack 9 is maintained, and a decrease in power generation efficiency is suppressed.
In addition, since the fuel cell module 1 is provided with a discharge route around the heat insulator 4, the heat insulator 4 as a whole is also enveloped with exhaust gas, so that the heat retention effect is further enhanced.

Therefore, according to the fuel cell module 1, the temperature of the fuel cell stack 9 can be more reliably maintained, and the decrease in the power generation efficiency can be more reliably suppressed.
Further, the main body 3 constituting the fuel cell module 1 of the present embodiment is formed by welding plate materials so that the combustion unit 30 becomes the wall surface of the evaporation unit 31, the reforming unit 32, and the heat exchange unit 33. It has a very simple structure.

Therefore, the fuel cell module 1 can be manufactured inexpensively and easily.
[Other Embodiments]
Although the embodiment has been described above, it is needless to say that the invention described in the claims is not limited to the above embodiment and can take various forms.

(1) The fuel cell module 1 described in the above embodiment is merely an example, and the present invention is not limited to this.
(2) In the said embodiment, although the fuel cell module 1 formed in the cylindrical shape was illustrated, it is not restricted to this.

(3) In the above embodiment, city gas is used as the raw fuel, but the raw fuel is not limited to this.
(4) In the above embodiment, air is used as the oxidant gas, but the oxidant gas is not limited to this.

  (5) In the above embodiment, the heat insulator 4 is used. As the heat insulator 4, a material known as a heat insulator may be used as a material. Such a thing may be used, for example, a sheet metal may be used.

  (6) In the above embodiment, only the reformed gas is sent from the fuel cell stack 9 to the combustion unit 30, but for example, raw fuel or oxidant gas may be sent.

DESCRIPTION OF SYMBOLS 1 ... Fuel cell module 2 ... Case 3 ... Main body part 4 ... Heat insulator 9 ... Fuel cell stack 30 ... Combustion part 31 ... Evaporation part 32 ... Reforming part 33 ... Heat exchange part 34 ... Heat exhaust space 39 ... Exhaust gas ventilation space 40 ... Gas vent hole 42 ... Discharge port 49 ... Heat insulation space 301 ... First pipe 302 ... Exhaust gas hole 312 ... First supply pipe 319 ... Bottom 321 ... Second pipe 328 ... Pass-through hole 329 ... Boundary part 331 ... Third pipe 332 ... 2nd supply pipe 341 ... Heat exhaust hole.

Claims (8)

A fuel cell reforming unit for constituting a fuel cell module together with a fuel cell stack in which a plurality of fuel cells that generate power by an electrochemical reaction between a reformed gas and an oxidant gas are stacked,
An evaporation section that generates water vapor;
A reforming unit that reforms a mixed gas of raw fuel and water vapor generated in the evaporation unit to generate the reformed gas, and sends the reformed gas to the fuel cell stack;
A heat exchanging unit that raises the temperature of the oxidant gas and sends the heated oxidant gas to the fuel cell stack;
Combusting the unreacted reformed gas discharged from the fuel cell stack, and generating the heat transmitted to the evaporation unit, the reforming unit, the heat exchange unit, and the fuel cell stack. Prepared,
The evaporation unit, the reforming unit, and the heat exchange unit are stacked, and the combustion unit is disposed adjacent to the evaporation unit, the reforming unit, and the heat exchange unit. A fuel cell reforming unit. The fuel cell reforming unit according to claim 1,
The reforming unit for a fuel cell, wherein the evaporating unit, the reforming unit, and the heat exchanging unit are formed in a shape surrounding the combustion unit in an annular shape. In the reforming unit for fuel cells according to any one of claims 1 to 2,
The fuel cell reforming unit is characterized in that the evaporating section is disposed at a lowermost stage. In the reforming unit for fuel cells according to any one of claims 1 to 3,
A reforming unit for a fuel cell, wherein a bottom portion of the evaporating portion is formed in a shape that is inclined upward from the inner side, which is the combustion portion side, to the outer side. In the fuel cell reforming unit according to any one of claims 1 to 4,
The reforming unit is disposed in the upper stage of the evaporation unit,
A reforming for a fuel cell, characterized in that a boundary part that forms a boundary between the reforming part and the evaporation part is formed in a shape that is inclined upward from the inner side which is the combustion part side to the outer side. unit. In the fuel cell reforming unit according to any one of claims 1 to 5,
The combustion part is
A reforming unit for a fuel cell that discharges an exhaust gas obtained by burning the reformed gas and the oxidant gas so as to spread over the entire lower surface of the fuel cell stack below the lower surface of the fuel cell stack. . The fuel cell reforming unit according to claim 6,
A heat insulator covering the fuel cell stack, the evaporation unit, the reforming unit, the heat exchange unit, and the entire combustion unit;
A housing that surrounds the heat insulator so as to form an exhaust gas ventilation space between the heat insulator, and
With
A fuel cell, wherein a discharge route for discharging the exhaust gas to the outside is formed from the gas vent hole provided in the heat insulator to the exhaust port provided in the housing through the exhaust gas ventilation space. Reforming unit. A fuel cell reforming unit according to any one of claims 1 to 7,
A fuel cell module comprising the fuel cell stack.