JPH0613097A - Solid electrolyte fuel cell power generation system - Google Patents

Abstract

PURPOSE:To reduce the amount of consumption of cooling air by the amount corresponding to reaction heat absorption so as to prevent the fall of bombing cycle effect and make a case smaller by disposing a fuel supply tube in each stack of a cell to directly cool the stack of the cells by steam reformation reaction heat absorption. CONSTITUTION:Natural gas and steam are supplied to each high temperature solid electrolyte fuel cell stack 22 through a fuel supply tube 25 after heating them at about 500 degrees centrigrade in a fuel supply chamber 24 by radiation and heat conduction and convective heat conduction from a power generating chamber 21 through a fuel discharging chamber 23. At this time, the steam reformation reaction takes place in the tube 25 so that methane as a main component of the natural gas reacts with the steam to change into hydrogen and carbon nonoxide. This reaction is an endothermic reaction and the reaction heat is supplied by the convective conduction heat by the discharged fuel and the heat generated by the solid electrolyte fuel cell in the power generating chamber 21. Air is heated up to 700 degrees centrigrade in a heat exchanger 28 which perform heat exchange with the discharged air and supplied to the power generating chamber 21. Oxygen in air consumed by the reaction in the cell, the temperature in the power generating chamber 21 rises from 900 to 1000 degrees centrigrade by the heat generated by the reaction and the discharged air is discharged out of the apparatus through a discharging tube 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a solid oxide fuel cell power generator.

[0002]

2. Description of the Related Art A natural gas containing methane as a main component and steam are caused to undergo a steam reforming reaction of methane at a nickel electrode which is a fuel electrode of a high temperature solid oxide fuel cell, and a part of heat generated in the fuel cell is converted to steam. The technology used as the endothermic reaction heat of the reforming reaction is called internal reforming technology. However, in a high temperature solid oxide fuel cell, the operating temperature is as high as 800 ° C to 1000 ° C, and even if the S / C ratio, which is the molar ratio of C (carbon) in water vapor and natural gas, is 3 or more, generation of carbon is observed at the fuel electrode. To be For this reason, conventionally, before the fuel is supplied to the solid electrolyte fuel cell, a partial reforming reaction is caused by the steam reforming reaction catalyst, and then the fuel is supplied to the high temperature solid electrolyte fuel cell. FIG. 2 shows a conventional internal reforming type solid oxide fuel cell power generator.

Reference numeral 1 in the figure denotes a power generation chamber. This power generation room 1
A cylindrical high-temperature solid electrolyte fuel cell stack 2 is arranged in which a plurality of solid electrolyte fuel cells, each having an air electrode inside and a fuel electrode outside, are connected in series. Natural gas and steam are supplied to the steam reforming catalyst 3, where most of methane reacts with steam and is decomposed into hydrogen and carbon monoxide. This fuel is supplied to the outside of the high temperature solid oxide fuel cell stack 2. On the other hand, air is supplied to the air supply chamber 4 above the power generation chamber 1 and then supplied to each high temperature solid electrolyte fuel cell stack 2 through the air supply pipe 5.

In the high temperature solid oxide fuel cell stack 2, 85% of the fuel reacts. The fuel that generated electricity is mixed and burned in the combustion chamber 6 with the air discharged from the high temperature solid oxide fuel cell stack 2. The combustion exhaust gas passes through the combustion exhaust gas exhaust pipe 7, supplies the reaction heat of the steam reforming catalyst 8, and is discharged to the outside of the power generation device. The entire power generator is insulated by the heat insulating material 9.

[0005]

However, the conventional internal reforming type solid electrolyte fuel cell has the following problems.

(1) If a partial steam reforming reaction occurs before the fuel is supplied to the high-temperature solid electrolyte fuel cell to absorb the reaction heat, the exhaust gas temperature of the high-temperature solid electrolyte fuel cell decreases, and the efficiency of the bottoming cycle decreases.

(2) Since the heat generated in the high temperature solid electrolyte fuel cell is not directly consumed by the internal reforming reaction endotherm, the high temperature solid electrolyte fuel cell is not cooled and the consumption of cooling air is not reduced. (3) Since the internal reforming catalytic reactor is attached to the high-temperature solid oxide fuel cell power generator, the entire power generator becomes large.

The present invention has been made in consideration of such circumstances, and the solid electrolyte fuel which can reduce the consumption of cooling air by the reaction endotherm, avoid the lowering of the bottoming cycle efficiency, and further make the entire apparatus compact. An object is to provide a battery power generator.

[0009]

SUMMARY OF THE INVENTION The present invention comprises a power generation room,
A cylindrical stack, which is provided in this power generation chamber, has a fuel electrode inside and a plurality of solid electrolyte fuel cells in which an air electrode is arranged outside is connected in series, and a fuel supply chamber that supplies fuel to the stack, A fuel discharge chamber for discharging the fuel reacted in the solid electrolyte fuel cell to the outside, a fuel supply pipe having one end communicating with the fuel supply chamber and the other end extending to the tip of the stack, and the fuel supply pipe. A solid electrolyte fuel cell power generator comprising: a steam reforming catalyst filled therein; and a heat exchanger for exchanging heat between air supplied to the power generation chamber and exhaust air.

[0010]

In the power generator of the present invention, the fuel such as natural gas and water vapor is heated to about 500 ° C. by radiation, heat conduction and convection heat conduction from the power generation chamber through the fuel discharge chamber to the fuel supply pipe. And is supplied to each high temperature solid electrolyte fuel cell stack. At this time, a steam reforming reaction occurs in the fuel supply pipe, methane, which is the main component of natural gas, reacts with steam, and changes into hydrogen and carbon monoxide. The reaction at this time is an endothermic reaction, and the reaction heat is covered by convective heat transfer by the exhaust fuel and heat generation of the solid electrolyte fuel cell in the power generation chamber 21.

On the other hand, in the high temperature solid oxide fuel cell stack, 700 is a heat exchanger for exchanging heat between air and exhaust air.
It is heated to ℃ and supplied to the power generation room. Oxygen in the air is consumed by the reaction of the solid oxide fuel cell, and the temperature of the power generation chamber rises from 900 ° C to 1000 ° C due to the heat generated by the reaction. Exhaust air is discharged to the outside of the power generator through the air discharge pipe.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

Reference numeral 21 in the figure denotes a power generation chamber. This power room 21
A cylindrical high-temperature solid electrolyte fuel cell stack 22 in which a plurality of solid electrolyte fuel cells having an air electrode on the inside and a fuel electrode on the outside are connected in series is arranged therein. A fuel discharge chamber 23 and a fuel supply chamber 24 are sequentially provided above the power generation chamber 21. The high temperature solid electrolyte fuel cell stack 22
Has a fuel supply pipe 25 whose one end communicates with the fuel supply chamber 24.
Is provided. In the fuel supply pipe 25, a granular steam reforming catalyst in which nickel is dispersed in an alumina carrier.
Filled with 26. An air exhaust pipe 27 is provided in the power generation chamber 21.
The air heat exchanger 28 is connected via. The entire power generation device is insulated by the heat insulating material 29.

In the solid oxide fuel cell power generator having such a structure, natural gas and water vapor are heated in the fuel supply chamber 24 through the fuel discharge chamber 23 from the power generation chamber 21 to about 500 ° C. by radiation, heat conduction and convection heat conduction. Is supplied to each high temperature solid electrolyte fuel cell stack 22 through the fuel supply pipe 25. At this time, a steam reforming reaction occurs in the fuel supply pipe 25, methane, which is the main component of natural gas, reacts with steam, and changes into hydrogen and carbon monoxide. The reaction at this time is an endothermic reaction, and the reaction heat is covered by convective heat transfer by the exhaust fuel and heat generation of the solid electrolyte fuel cell in the power generation chamber 21.

On the other hand, in the high temperature solid oxide fuel cell stack 22, air is exchanged with exhaust air by a heat exchanger 28.
It is heated to 00 ° C and supplied to the power generation chamber 21. Oxygen in the air is consumed by the reaction of the solid oxide fuel cell, and the heat generated by the reaction raises the temperature of the power generation chamber 21 from 900 ° C to 1000 ° C. Exhaust air is discharged to the outside of the power generation device through the air discharge pipe 27. Therefore, the internal reforming type solid oxide fuel cell power generator according to the above embodiment has the following advantages.

(1) Each stack of high temperature solid oxide fuel cell
Since the fuel supply pipe 25 is arranged inside the high temperature solid electrolyte fuel cell stack 22,
Is directly cooled, and the amount of cooling air consumed is reduced by the reaction endotherm.

(2) The exhaust gas temperature at the outlet of the high temperature solid oxide fuel cell is the same as that of the system that does not cause the steam reforming reaction because there is no change in the total heat balance because the amount of cooling air absorbed by the steam reforming reaction decreases. The bottoming cycle efficiency does not decrease. (3) Since the reforming catalyst is filled inside the fuel supply pipe, a special space for filling the catalyst is not required, and the size of the entire apparatus does not change.

In the above embodiment, the case of using a granular steam reforming catalyst in which nickel is dispersed in an alumina carrier is, of course, not limited to this.

[0019]

As described above in detail, according to the present invention,
In addition to reducing the reaction endothermic amount of cooling air consumption,
It is possible to provide a solid oxide fuel cell power generation device which can avoid a decrease in bottoming cycle efficiency and can make the entire device more compact than conventional devices.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a solid oxide fuel cell power generator according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional solid oxide fuel cell power generator.

[Explanation of symbols]

21 ... Power generation chamber, 22 ... Solid electrolyte fuel cell stack, 2
3 ... Fuel discharge chamber, 24 ... Fuel supply chamber, 25 ... Fuel supply pipe, 26 ... Steam reforming catalyst, 27 ... Air discharge pipe, 28 ...
Air heat exchanger, 29 ... Insulation material.

Claims (1)

[Claims] 1. A power generation chamber, a cylindrical stack provided in the power generation chamber, in which a plurality of solid electrolyte fuel cells each having a fuel electrode inside and an air electrode outside are connected in series, and to the stack. A fuel supply chamber for supplying fuel, a fuel discharge chamber for discharging the fuel reacted in the solid oxide fuel cell to the outside, a fuel having one end communicating with the fuel supply chamber and the other end extending to the tip of the stack. A solid electrolyte fuel cell comprising a supply pipe, a steam reforming catalyst filled in the fuel supply pipe, and a heat exchanger for exchanging heat between air supplied to the power generation chamber and exhaust air. Power generator.