Solid oxide fuel cell device

Patent metadata

Field	Value
Publication number	US-9780391-B2
Application number	US-201313944289-A
Country	US
Kind code	B2
Filing date	Jul 17, 2013
Priority date	Jul 19, 2012
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

To provide a fuel cell device capable of extending the years of service life of a reformer by suppressing thermal runaways. The present invention is a solid oxide fuel cell device, including a fuel cell module having fuel cell units; a reformer disposed above the fuel cell units, for producing hydrogen by a partial oxidation reforming reaction and a steam reforming reaction; a vaporizing chamber disposed adjacent to the reformer; a combustion chamber for heating the vaporization chamber; a water supply device; an electrical generation oxidant gas supply device; and a controller for raising the fuel cell units to a temperature at which electrical generation is possible; whereby over the entire period of the startup step, the reforming oxidant gas supply device and water supply device are controlled so that partial oxidation reforming reactions do not occur independently in the reformer.

First claim

What is claimed is:

1. A solid oxide fuel cell system, in which excess fuel not used to generate electricity flows out from one ends of fuel cell units and is combusted to heat a reformer, the solid oxide fuel cell system comprising:
a fuel cell module including a plurality of fuel cell units in each of which a fuel electrode is formed on an interior passage for passing the fuel therethrough;
a reformer disposed inside the fuel cell module above the plurality of fuel cell units, wherein the reformer is configured to produce hydrogen and a byproduct including carbon monoxide generated from a concurrent occurrence of a partial oxidation reforming (POX) reaction caused by a chemical reaction between the fuel and reforming oxidant gas, and a steam reforming (SR) reaction caused by a chemical reaction between the fuel and reforming steam;
a vaporization chamber disposed above the plurality of fuel cell units and adjacent to the reformer, the vaporization chamber being configured to vaporize supplied water to produce the reforming steam;
a combustion chamber disposed inside the fuel cell module below the reformer and the vaporization chamber above the fuel cell units, wherein the combustion chamber is configured to combust the excess fuel flowing out from the interior passage of each of the fuel cell units to heat the reformer and the vaporization chamber located above the combustion chamber;
a fuel supply device configured to supply the fuel to the reformer to thereby feed the reformed fuel into each of the fuel cell units;
a reforming oxidant gas supply device configured to supply the reforming oxidant gas to the reformer;
a water supply device configured to supply the reforming water to the vaporization chamber;
an oxidant gas supply device configured to supply oxidant gas for electrical generation to an oxidant gas electrode formed on an exterior of each of the plurality of fuel cell units;
an ignitor provided in the combustion chamber and operable to ignite the excess fuel flowing out of the fuel cell units;
a temperature sensor arranged to detect an operation temperature of the fuel cell module; and
a controller programmed to execute a startup process of the fuel cell module to simultaneously effect the POX reaction and the SR reaction in the reformer so that during the startup process, the plurality of fuel cell units can be heated from a room temperature to a temperature at which electrical generation is possible,
wherein the controller is programmed to execute the startup process in a sequence of operations comprising:
operating the reforming oxidant gas supply device and the fuel supply device to start supplying the reforming oxidant gas and the fuel to the reformer at the room temperature;
subsequent to a start of supply of the reforming oxidant gas and the fuel to the reformer, operating the ignitor to ignite the excess fuel flowing out of the fuel cell units; and
upon a confirmation by the controller that a temperature detected by the temperature sensors reaches an ignition temperature, operating the water supply device to start supplying the reforming water to the reformer so that during the entire period of the startup process, the POX reaction will not occur solitarily in the reformer, wherein the ignition temperature is indicative of combustion of the excess fuel and lower than a temperature at which the POX reaction is occurrable.

2. The solid oxide fuel cell device of claim 1 , wherein the controller is programmed to execute an auto thermal reforming (ATR) reaction in the reformer in which the POX reaction and the SR steam reforming reaction occur simultaneously in the reformer, and the controller is further programmed to execute the startup process in such a manner that only the ATR reaction and the SR reaction will occur in the reformer during the entire period of the startup process.

3. The solid oxide fuel cell device of claim 2 , wherein the controller is programmed to operate the reforming oxidant gas supply device to adjust a supply amount of the reforming oxidant gas in such a manner that a ratio between oxygen O 2 in the reforming oxidant gas and carbon in the fuel will be at all times less than a ratio O 2 /C=0.4, at which ratio all of the fuel is reformable in the reformer only through the POX reaction.

4. The solid oxide fuel cell device of claim 2 , wherein the controller is programmed to execute the ATR reaction in multiple stages, and the controller is programmed to operate the water supply device in an initial stage of the ATR reaction to supply the reforming water at a rate which is smallest throughout the startup process.

5. The solid oxide fuel cell device of claim 1 , wherein the controller is programmed to temporarily operate the water supply device to supply the reforming water for a limited time before operating the ignitor to ignite the excess fuel.

6. The solid oxide fuel cell device of claim 4 wherein at a transition from the initial stage of the ATR reaction (an ATR1 reaction) to a second stage of the ATR reaction (an ATR2 reaction), the controller is programmed to operate the water supply device to increase supply of the reforming water while operating the reforming oxidant gas supply device to maintain supply of the reforming oxidant gas at a fixed supply rate.

7. The solid oxide fuel cell device of claim 6 , wherein the controller is programmed to operate the fuel supply device to maintain supply of the fuel at a fixed supply rate at the transition from the ATR1 reaction to the ATR2 reaction.

8. The solid oxide fuel cell device of claim 7 , wherein at a transition from the ATR2 reaction to a third stage of the ATR reaction (an ATR3 reaction), the controller is programmed to operate the fuel supply device and the reforming oxidant gas supply device to reduce supply rates of the fuel and the reforming oxidant gas, while operating the water supply device to maintain supply of the reforming water at a constant supply rate.

9. The solid oxide fuel cell device of claim 3 , further comprising:
an external heat insulation material arranged to reduce heat dissipation to outside of the fuel cell module;
a heat exchanger disposed above the vaporization chamber and configured to exchange heat between combustion gas produced in the combustion chamber and the oxidant gas for electrical generation introduced into the fuel cell module so as to preheat the oxidant gas for electrical generation before the oxidant gas is supplied to the plurality of fuel cell units; and
a vaporization chamber temperature-raising insulation layer disposed between the heat exchanger and the vaporization chamber and configured to suppress migration of heat from the vaporization chamber to the heat exchanger to thereby facilitate an increase of a temperature of the vaporization chamber.

10. The solid oxide fuel cell device of claim 9 , wherein a thermal resistance of the vaporization chamber temperature-raising insulation layer is less than a thermal resistance of the external heat insulation material.

11. The solid oxide fuel cell device of claim 10 , wherein the vaporization chamber temperature-raising insulation layer is disposed to entirely cover the vaporization chamber.

12. The solid oxide fuel cell device of claim 11 , wherein the vaporization chamber temperature-raising insulation layer comprises one of (i) a vaporization chamber insulating material disposed between the heat exchanger and the vaporization chamber and (ii) a gas retaining space provided between the heat exchanger and the vaporization chamber.

13. The solid oxide fuel cell device of claim 12 , further comprising an exhaust pathway disposed between a reforming section/vapor

Assignees

• Toto Ltd

Inventors

• Akagi Yousuke
• Abe Toshiya
• Otsuka Toshiharu
• Tsuchiya Katsuhisa
• Matsuo Takuya
• Watanabe Naoki
• Omura Hajime
• Tanaka Shuhei
• Hoshiko Takuya

Classifications

• Y02E60/50

  Fuel cells · CPC title

• C01B2203/0233

  the reforming step being a steam reforming step · CPC title

• H01M8/0618

  Reforming processes, e.g. autothermal, partial oxidation or steam reforming · CPC title

• H01M8/04828 Primary

  Humidity; Water content · CPC title

• H01M8/04776

  at auxiliary devices, e.g. reformer, compressor, burner · CPC title