JPH08287937A - Solid electrolyte fuel cell module - Google Patents

Abstract

PURPOSE: To dispense with a reformer of a separate body, and attain improvement in evergy efficiency, weight reduction in a device and cost reduction by filling a steam reforming catalyst in a fuel supply chamber of a vessel having a power generation chamber, directly supplying reformed gas to a stack. CONSTITUTION: A stack 2 formed by connecting solid electrolyte fuel cells whose fuel electrode and air electrode are arranged on an inside and outside surfaces of solid electrolyte in a plurality in series to each other, is vertically arranged in a power generation chamber 1 in a vessel 12 having a heat insulating material 9. A fuel supply chamber 3 is arranged above it, and a steam reforming catalyst 100 is filled in it, and hydrocarbon and steam are introduced here from a fuel introducing pipe 13, and they are reacted with each other. Generated Ha and CO are supplied to the stack 2 through a fuel supply pipe 4. On the other hand, air from an air introducing pipe 15 is preheated by a heat exchanger 6, and is passed through the stack 2, and high temperature waste air is discharged through discharge pipes 8 and 16 and the heat exchanger 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell module for reforming a supplied hydrocarbon fuel into a fuel gas which does not hinder the power generation of a solid electrolyte fuel cell in a fuel supply chamber. Regarding

[0002]

2. Description of the Related Art A hydrocarbon fuel such as natural gas containing methane as a main component and steam are directly supplied to cause a steam reforming reaction of methane at a nickel electrode which is a fuel electrode of a high temperature solid oxide fuel cell. Further, a technique in which a part of the heat generated in the solid oxide fuel cell is utilized as the endothermic reaction heat of this steam reforming reaction is called an internal reforming technique.

However, this internal reforming technique has a high operating temperature of 800 ° C. to 1000 ° C. in a solid electrolyte fuel cell, and S, which is the molar ratio of C (carbon) in water vapor and natural gas.
Even if / C is 3 or more, generation of carbon is seen at the fuel electrode,
There is a problem when applied to a solid oxide fuel cell. Therefore, in the conventional solid oxide fuel cell system, a reforming device is provided before the solid oxide fuel cell module is supplied to the solid oxide fuel cell module to cause a partial steam reforming reaction of natural gas,
After making the fuel gas, it is supplied to the solid electrolyte fuel cell module to solve the problem.

FIG. 2 is a view showing a cross section of such a conventional solid electrolyte fuel cell module. In the figure,
Inside the container 12 whose outer periphery is covered with the heat insulating material 9, the power generation chamber 1 is formed by partitioning the upper part thereof with the lower tube sheet 11. In the power generation chamber 1, a plurality of solid electrolyte fuel cells in which a fuel electrode is arranged inside and an air electrode is arranged outside through an electrolyte, are connected in series, and a cylindrical solid electrolyte fuel having a closed lower end is formed. A large number of battery stacks 2 (hereinafter simply referred to as stacks) are arranged in a vertical state.

Further, above the power generation chamber 1 in the container 12,
The lower tube sheet 11 and the lower tube sheet 11 are spaced apart from each other, and the fuel discharge chamber 5 defined by the upper tube sheet 10 provided above the lower tube sheet 11 is further provided at the upper end of the container 12 above the upper tube sheet. Each of the fuel supply chambers 3 is divided into lower parts by 10, and is defined. Further, a fuel supply pipe 4 is installed at the cylindrical axis of the stack 2, and the upper end of the fuel supply pipe 4 is located at the fuel supply chamber 3
And the lower end is in communication with the lower end of the stack 2 whose lower end is closed. Further, an air heat exchanger 6 is provided below the power generation chamber 1 inside the container 12 partitioned by a radiant converter (not shown) and at a distance from the radiant converter.

Further, a fuel introduction pipe 13 for supplying the fuel gas SF from the outside is connected to the fuel supply chamber 3, and a partial modification of natural gas NG is provided in the middle of the fuel introduction pipe 13. A reformer 07 for quality reaction is provided. That is, the natural gas NG and the steam ST supplied from the outside through the fuel introduction pipe 13 enter the reforming device 07, where a part of methane, which is the main component of the natural gas NG, is modified together with the natural gas NG. Steam S transferred to the quality device 07
It reacts with T and is decomposed and reformed into a fuel gas SF of hydrogen and carbon monoxide. The fuel gas SF is further supplied to the fuel supply chamber 3 through the fuel introduction pipe 13.

Fuel gas SF supplied to the fuel supply chamber 3
Is supplied from the fuel supply chamber 3 to the lower end of the stack 2 through the fuel supply pipe 4. Stack 2 with closed bottom
The fuel gas SF supplied to the lower end of the stack 2 is on the outer peripheral surface of the fuel supply pipe 4 installed at the axial center of the stack 2 and the stack 2
When it rises between the inner peripheral surfaces of the exhaust fuel EF after being used for power generation reaction in the fuel electrode provided inside the stack 2.
Therefore, the lower tube sheet 10 with the upper end of the stack 2 opened
And is collected in the fuel discharge chamber 5 and exhausted from the inside of the container 12 by the fuel discharge pipe 14 provided in the fuel discharge chamber 5.

Further, the stack 2 together with the fuel gas SF
The supply air SA used for power generation is supplied to the air heat exchanger 6 from the outside by the air introduction pipe 15 connected to the air heat exchanger 6. The air heat exchanger 6 is connected to the lower end of an air discharge pipe 8 vertically installed in the power generation chamber 1 in order to discharge the exhaust air EA heated in the power generation chamber 1 to the outside of the container 12. The supply air SA supplied to the air heat exchanger 6 through the air introduction pipe 15 is preheated by performing regenerative heat exchange with the exhaust air EA similarly supplied through the air discharge pipe 8. The supply air SA preheated by the air heat exchanger 6 is supplied below the radiation conversion body formed of a porous material that defines the lower portion of the power generation chamber 1. The radiant converter receives the heat from the power generation chamber 1 which has become high temperature due to the heat radiated from the stack 2,
The preheated supply air SA, which has a high temperature and passes through it, is further heated.

In this way, by utilizing the heat generated in the power generation chamber 1 to further heat the supply air SA preheated in the air heat exchanger 6 in the radiation converter, the air in the power generation chamber 1 can be heated. It is possible to suppress the temperature rise width and reduce the temperature difference inside the power generation chamber 1. The supply air SA, which has passed through the radiation converter and is supplied into the power generation chamber 1, rises along the outer peripheral surface of the stack 2, which is vertically arranged in the power generation chamber 1, and outside the stack 2. It is used for power generation reaction in the air electrode provided in the above, and cools the inside of the power generation chamber 1. Moreover, it is used for power generation etc. in the power generation room 1, and 900-100
The exhaust air EF heated to 0 ° C. is collected in the air exhaust pipe 8 described above, introduced into the air heat exchanger 6 and used to preheat the supply air SA as described above, and then the air exhaust pipe 1
It is exhausted to the outside of the container 12 by 6.

As described above, the inside of the power generation chamber 1 must be maintained at a high temperature of 900 to 1000 ° C. for power generation in the stack 2, and as described above, the outer periphery of the container 12 that houses the power generation chamber 1 therein. It is kept warm by the heat insulating material 9 which encloses it, so that the high temperature is kept. Further, the lower tube sheet 11 that divides the upper portion of the power generation chamber 1 supports the stack 2 that is vertically arranged in the power generation chamber 1, and at the same time, the exhaust fuel EF in the fuel discharge chamber 5 and the inside of the power generation chamber 1 Supply air SA,
Alternatively, the mixed combustion with the exhaust air EA is prevented. Further, the fuel discharge chamber 5 is partitioned together with the lower tube sheet 11,
The upper tube sheet 10 that defines the lower portion of the fuel supply chamber 3 installed at the upper end of the container 12 supports the fuel supply pipe 4 that hangs down from the axial center of the stack 2, and also supports the fuel supply chamber 3 and the fuel discharge chamber. 5 and the partition wall 5 prevent the fuel gas SF and the exhaust fuel EF from being mixed.

However, in order to obtain the fuel gas used in such a conventional solid electrolyte fuel cell module, the reformer 03 used in the steam reforming reaction of natural gas 03.
However, in addition to requiring a device separate from the solid electrolyte fuel cell module, there are the following problems. (1) The steam reforming reaction is an endothermic reaction, and it is necessary to heat the reforming device 03 by burning a part of the exhausted fuel EA or the fuel gas SF from the power generation chamber 1, which lowers the efficiency of the system. To do. (2) The temperature of the power generation chamber 1 is 900 to 1000 ° C.,
Since the temperatures of the lower and upper tube plates 11 and 10 supporting the stack 2 and the fuel supply pipe 4 become high, it is necessary to increase the thickness and use a high-grade material. (3) High temperature heat radiation from the lower and upper tube sheets 10 and 11 to the outside of the container 12 increases, the amount of heat that can be recovered from the power generation chamber 1 decreases, and the system efficiency decreases.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional solid oxide fuel cell module, and thus it is not necessary to install a separate reformer.
There is no need to supply combustion gas from fuel or exhausted fuel to the heating required for the steam reforming reaction, and it is possible to prevent overheating of the lower and upper tube sheets, reduce weight and cost, and reduce heat radiation to the outside. It is an object of the present invention to provide a solid oxide fuel cell module capable of improving thermal efficiency.

[0013]

SUMMARY OF THE INVENTION In order to solve the problems of the above-mentioned conventional solid oxide fuel cell module, the present invention provides a fuel supply chamber installed in an upper part of a power generation chamber inside a container, from the outside of the fuel supply chamber. The hydrocarbon fuel supplied to
A steam reforming catalyst that reacts with steam to reform into hydrogen and carbon monoxide fuel gas was filled.

[0014]

In the solid electrolyte fuel cell module of the present invention,
By the means described above, a steam reforming reaction occurs in the fuel supply chamber, the supplied hydrocarbon fuel reacts with steam, and is reformed into a fuel gas partially converted into hydrogen and carbon monoxide. The reaction at this time is an endothermic reaction, and the reaction heat is covered by heating by the exhaust fuel exhausted to the fuel discharge chamber and heating by the power generation chamber radiated to the fuel supply chamber through the fuel discharge chamber.

As a result, it is not necessary to install a reforming device for carrying out the steam reforming reaction, and the reforming device, which was necessary for heating the reforming device, was provided outside the vessel from the power generation chamber. It is not necessary to supply exhausted fuel that is transferred to and burned, or to use the fuel, so that the efficiency of the system can be improved.

Further, the heat absorption by the steam reforming reaction in the fuel supply chamber cools the upper tube plate and the lower tube plate which are heated by the heat radiation from the power generation chamber, so that the temperature rise can be prevented. As a result, it becomes unnecessary to increase the wall thickness of these tube sheets or to use high-grade materials, and it is possible to achieve weight reduction and cost reduction. In addition, by preventing these tube plates from becoming hot, the amount of heat released from these parts through the heat insulating material to the outside of the container can be reduced, and the amount of heat generated in the power generation chamber can be recovered more. Can be used as another heat source, which can improve thermal efficiency and increase system efficiency.

[0017]

Embodiments of the solid oxide fuel cell module of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing an embodiment of the solid oxide fuel cell module of the present invention. The same members as those shown in FIG. 2 are
The same reference numerals are given and the description is omitted.

In the figure, in a power generation chamber 1, a cylindrical stack 2 in which a plurality of solid electrolyte fuel cells having a fuel electrode inside and an air electrode outside are connected in series is arranged in a vertical state. . The lower end of the stack 2 is closed and disconnected from the power generation chamber 1. The natural gas NG and the steam ST from the outside are supplied to the fuel supply chamber 3 installed above the power generation chamber 1 through the fuel introduction pipe 13. Fuel supply chamber 3
The inside of is filled with the steam reforming catalyst 100,
Here, a part of methane, which is the main component of the supplied natural gas NG, reacts with water vapor, and is decomposed into hydrogen and carbon monoxide fuel gas SF for reforming.

The fuel supply pipe 4 is installed at the axial center of the cylindrical stack 2 and has its upper end opened to the fuel supply chamber 3. Reformed fuel gas SF when passing through the fuel supply chamber 3.
Is supplied to the lower end of the stack 2 from the fuel supply chamber 3 through the fuel supply pipe 4, and is distributed to the inner peripheral surface of the stack 2 when the inner peripheral surface of the stack 2 and the outer peripheral surface of the fuel supply pipe 4 rise. After power generation reaction with the installed fuel electrode and use for power generation, the stack 2 is collected in the open fuel discharge chamber 5 and exhausted to the outside by the fuel discharge pipe 14 connected to the upper end of the fuel discharge chamber 5. It

The supply air SA exchanges heat with the exhaust air EA introduced from the power generation chamber 1 through the air exhaust pipe 8 by the air heat exchanger 6 provided in the lower portion of the power generation chamber 1,
After being preheated, it passes through a radiant converter that defines the lower part of the power generation chamber 1, is further heated, and is supplied to the power generation chamber 1. Then, when the inside of the power generation chamber 1 is raised, power generation reaction is performed with an air electrode provided outside the stack 2 to generate power. Due to this power generation reaction, the exhaust air EA heated to 900 to 1000 ° C. is collected in the air exhaust pipe 8 and the air heat exchanger 6
As described above, after heat exchange with the supply air SA, the air is exhausted to the outside through the air exhaust pipe 16.

It is necessary to keep the inside of the power generation chamber at a high temperature of 900 to 1000 ° C., and the entire power generation chamber 1 is kept warm by the heat insulating material 9. The lower tube sheet 11 supports the solid electrolyte fuel cell stack 2 and at the same time prevents the exhaust fuel EF and the supply air SA or the exhaust air EA in the power generation chamber 1 from being mixed and burned. The upper tube sheet 10 supports the fuel supply pipe 4 and serves as a partition wall between the fuel supply chamber 3 and the fuel discharge chamber 5.

In the solid oxide fuel cell module having such a structure, the heat absorption due to the steam reforming reaction in the fuel supply chamber 3 to which the natural gas NG and the steam ST are supplied is transferred from the power generation chamber 1 to the lower tube sheet 11. It is covered by the radiant heat radiated to the upper tube sheet 10 and the fuel supply chamber 3 and the heat of the exhaust fuel EA heated by the power generation reaction.

[0023]

As described above, according to the solid oxide fuel cell module of the present invention, the following effects can be obtained with the configuration shown in the claims.

(1) Since the steam reforming catalyst is installed in the fuel supply chamber above the power generation chamber of the high temperature solid oxide fuel cell module, hydrocarbon fuel such as natural gas containing methane as a main component is solidified. There is no need to install a reformer installed separately to reform the fuel gas of the electrolyte fuel cell. Also, the steam reforming reaction can be carried out by utilizing the heat loss from the high temperature power generation chamber to the upper part, and the heating of the reforming fuel and the exhaust fuel by the combustion gas is not required, and the thermal efficiency of the system can be improved. .

(2) Utilizing the endotherm of the steam reforming reaction,
Cooling the lower and upper tubesheets can prevent these tubesheets from overheating. Due to the lower temperature of this tube sheet, it was necessary to maintain the strength of the tube sheet at high temperature,
The wall thickness can be reduced or the material can be made low-grade.

(3) Since the temperature of the tube sheet lowers, the amount of heat discharged from the tube sheet portion to the outside is small, and the heat generated in the power generation chamber can be effectively used for other equipment required by the system. It is also possible to improve the thermal efficiency of the system.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a solid oxide fuel cell module of the present invention,

FIG. 2 is a side sectional view showing an example of a conventional solid oxide fuel cell module.

[Explanation of symbols]

 1 Power Generation Chamber 2 (Solid Electrolyte Fuel Cell) Stack 3 Fuel Supply Chamber 4 Fuel Supply Pipe 5 Fuel Discharge Chamber 6 Air Heat Exchanger 8 Air Discharge Pipe 9 Heat Insulation Material 10 Upper Tube Sheet 11 Lower Tube Sheet 12 Container 13 Fuel Inlet Tube 14 Fuel exhaust pipe 15 Air inlet pipe 16 Air exhaust pipe 100 Steam reforming catalyst 07 Reforming device SA Supply air EA Exhaust air SF Fuel gas EF Exhaust fuel NG Natural gas ST Steam

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Nagata 1-1, Atsunouramachi, Nagasaki City Mitsubishi Heavy Industries Ltd. Nagasaki Shipyard Co., Ltd.

Claims (1)

[Claims] 1. A solid electrolyte fuel cell in which a power generation chamber defined inside a container surrounded by a heat insulating material, a fuel electrode disposed vertically in the power generation chamber through an electrolyte, an inner fuel electrode, and an outer air electrode are disposed. A plurality of cylindrical stacks connected in series and closed at the lower end, a fuel supply chamber defined in the container above the power generation chamber, and partitioned between the power generation chamber and the fuel supply chamber,
A fuel discharge chamber having an upper end of the stack opened, a fuel supply pipe having one end opened to the fuel supply chamber and the other end opened to a lower end of the stack, and a fuel supply pipe inserted into the stack, and the inside of the container. Installed below the power generation room
In a solid electrolyte fuel cell module comprising an air heat exchanger for preheating supply air supplied to the power generation chamber, a steam reformer for reacting hydrocarbon fuel supplied from the outside with steam to reform hydrogen and carbon monoxide A solid electrolyte fuel cell module, wherein a solid catalyst is filled in the fuel supply chamber.