JP3732058B2

JP3732058B2 - Solid polymer electrolyte fuel cell system

Info

Publication number: JP3732058B2
Application number: JP33828099A
Authority: JP
Inventors: 智倫麻生; 正高尾関; 伸二宮内
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 1999-11-29
Filing date: 1999-11-29
Publication date: 2006-01-05
Anticipated expiration: 2019-11-29
Also published as: JP2001155748A

Description

【０００１】
【発明の属する技術分野】
本発明は、固体高分子電解質型燃料電池の燃料極から排出されるオフガスを、燃料ガスとして利用する固体高分子電解質型燃料電池システムに関する。
【０００２】
【従来の技術】
従来の固体高分子電解質型燃料電池システムを図４に示す。図４中、１は固体高分子電解質型燃料電池であり、一般に固体高分子電解質膜を挟んだ空気極２と燃料極３から構成されている。空気極２の上流側は、酸化剤ガスＡとして例えば空気を供給するファン４と連通されている。供給された空気は、空気極２と接する所定の通路を下流側へ向かって流れる。このとき、空気中の酸素が必要量だけ電極反応で消費され、残りのガスＡ’は外部へ排出される。
【０００３】
一方、燃料極３の上流側は、改質器５に連通されている。そして、天然ガスなどの原料ガスＸおよび水蒸気改質反応に必要な原料水Ｙが改質器５に供給される。改質器５は、自身を加熱するための燃焼部６を具備しており、燃焼部６にはガス量制御手段７から連通部１１を介して燃料ガスＦが供給される。ガス量制御手段７としては、一般に制御弁などが用いられる。燃料ガスＦが燃焼部６で燃焼すると、改質器５が所定の温度に昇温される。このとき、改質器５では、原料ガスＸと原料水Ｙとの反応が起こり、水素リッチな改質ガスＧが生成する。
【０００４】
改質ガスＧは、燃料極３に供給され、燃料極３と接する所定の通路を下流側へ向かって流れる。このとき、改質ガスＧ中の水素が必要量だけ電極反応で消費され、残ったガスはオフガスＧ’として外部へ排出される。すなわち、発電によって一部の水素が消費された後、燃料極３の下流側から水素を含むオフガスＧ’が外部に排出されるようになっている。
【０００５】
【発明が解決しようとする課題】
従来の固体高分子電解質型燃料電池システムでは、上述したように、水素を含むオフガスが外部に排出されてしまう。そのため、燃料電池システムの運転効率が低いという問題がある。また、オフガスが外部に排出されると、オフガス中の水素が周囲の空気と混合して可燃性のガスとなる可能性がある。したがって、水素が外部へ流出することのない高効率で安全性の高い固体高分子電解質型燃料電池システムの開発が望まれている。
【０００６】
【課題を解決するための手段】
本発明は、上記問題を解決するために、燃焼部６とガス量制御手段７とを接続する連通部１１に、燃料極から排出されるオフガスＧ’を合流させる合流部を設けたものである。そして、ガス量制御手段を制御する所定の制御部を備えたものである。
すなわち、本発明は、原料ガスから改質ガスを生成する改質器と、前記改質器で得られた改質ガスと酸化剤ガスとを用いて発電を行う固体高分子電解質型燃料電池と、前記改質器を加熱するための燃焼部と、前記燃焼部に供給される燃料ガス量を調節するガス量制御弁と、前記ガス量制御弁と前記燃焼部とを繋ぐ連通部とを具備し、前記固体高分子電解質型燃料電池の燃料極から排出されるオフガスを前記連通部に合流させる合流部と、前記ガス量制御弁を通過する燃料ガス量を制御する制御部とを有し、前記制御部は、前記連通部内部の流路抵抗が大きくなると、前記ガス量制御弁の開度を大きくし、前記連通部内部の流路抵抗が小さくなると、前記ガス量制御弁の開度を小さくする固体高分子電解質型燃料電池システムに関する。
【０００７】
また、本発明は、原料ガスから改質ガスを生成する改質器と、前記改質器で得られた改質ガスと酸化剤ガスとを用いて発電を行う固体高分子電解質型燃料電池と、前記改質器を加熱するための燃焼部と、前記燃焼部に供給される燃料ガス量を調節するガス量制御弁と、前記ガス量制御弁と前記燃焼部とを繋ぐ連通部とを具備し、前記固体高分子電解質型燃料電池の燃料極から排出されるオフガスを前記連通部に合流させる合流部と、前記ガス量制御弁を通過する燃料ガス量を検知するガス量検知手段と、前記ガス量検知手段の検知した値に基づいて前記ガス量制御弁を制御する制御部とを有し、前記制御部は、前記オフガスが前記合流部から前記連通部内部の燃料ガスに混入され、燃料ガスとともに前記燃焼部に供給される際に、前記連通部内部の流路抵抗が大きくなり、前記ガス量検知手段が検知する燃料ガス量が小さくなると、前記ガス量制御弁の開度を大きくし、前記連通部内部の流路抵抗が小さくなり、前記ガス量検知手段が検知する燃料ガス量が大きくなると、前記ガス量制御弁の開度を小さくする固体高分子電解質型燃料電池システムに関する。
【０００８】
また、本発明は、原料ガスから改質ガスを生成する改質器と、前記改質器で得られた改質ガスと酸化剤ガスとを用いて発電を行う固体高分子電解質型燃料電池と、前記改質器を加熱するための燃焼部と、前記燃焼部に供給される燃料ガス量を調節するガス量制御弁と、前記ガス量制御弁と前記燃焼部とを繋ぐ連通部とを具備し、前記固体高分子電解質型燃料電池の燃料極から排出されるオフガスを前記連通部に合流させる合流部と、前記連通部内部の圧力を検知する圧力検知手段と、前記圧力検知手段の検知した値に基づいて前記ガス量制御弁を制御する制御部とを有し、前記制御部は、前記オフガスが前記合流部から前記連通部内部の燃料ガスに混入され、燃料ガスとともに前記燃焼部に供給される際に、前記圧力検知手段により検知された圧力が大きくなると、前記ガス量制御弁の開度を大きくし、前記圧力検知手段により検知された圧力が小さくなると、前記ガス量制御弁の開度を小さくする固体高分子電解質型燃料電池システムに関する。
【０００９】
また、本発明は、原料ガスから改質ガスを生成する改質器と、前記改質器で得られた改質ガスと酸化剤ガスとを用いて発電を行う固体高分子電解質型燃料電池と、前記改質器を加熱するための燃焼部と、前記燃焼部に供給される燃料ガス量を調節するガス量制御弁と、前記ガス量制御弁と前記燃焼部とを繋ぐ連通部とを具備し、前記固体高分子電解質型燃料電池の燃料極から排出されるオフガスを前記連通部に合流させる合流部と、前記固体高分子電解質型燃料電池で発電された電力の電流値を検知する電流検知手段と、前記電流検知手段の検知した値に基づいて前記ガス量制御弁を制御する制御部とを有し、前記制御部は、前記オフガスが前記合流部から前記連通部内部の燃料ガスに混入され、燃料ガスとともに前記燃焼部に供給される際に、前記電流検知手段により検知された電流より推定されるオフガス量が大きくなると、前記ガス量制御弁の開度を大きくし、前記電流検知手段により検知された電流より推定されるオフガス量が小さくなると、前記ガス量制御弁の開度を小さくする固体高分子電解質型燃料電池システムに関する。なお、原料ガスとしては、主として炭化水素系の原料ガスが用いられる。
【００１０】
【発明の実施の形態】
本発明の燃料電池システムでは、燃料極から排出されたオフガスが、燃焼部とガス量制御手段とを繋ぐ連通部に設けられた合流部から燃料ガスに混入され、燃料ガスとともに燃焼部に供給される。そのため、システムの運転効率が高められる。
ただし、オフガスの混入によって合流部下流のガス流量が増加するので、流路抵抗が大きくなり、制御手段を通過する燃料ガス量が少なくなる。また、オフガス量は、固体高分子電解質型燃料電池に繋がれる負荷の変動など、様々な要因によって変化する。
【００１１】
そこで、本発明の燃料電池システムにおいては、ガス量制御手段を通過する燃料ガス量を制御する制御部を設けている。そして、所定の検知手段が検知した値に基づいてガス量制御手段が制御される。
したがって、燃料電池と接続された電力負荷が変化するなどして合流部に混入されるオフガス量が変化しても、燃焼部に供給される燃料ガス量を所定範囲に保持することができ、燃焼部を安定な状態で維持することができる。
【００１２】
実施の形態１
燃料電池の燃料極から排出されたオフガスが連通部に設けられた合流部から燃料ガスに混入されると、オフガスの混入によって合流部下流のガス流量が変化し、流路抵抗も変化する。そのため、ガス量制御手段を通過する燃料ガス量も変化する。
そこで、本実施の形態に係る固体高分子電解質型燃料電池システムにおいては、前記ガス量制御手段の上流側または下流側にガス量検知手段が設置されている。前記ガス量検知手段は、前記ガス量制御手段を通過する燃料ガス量を検知し、検知された値は制御部に伝達される。そして、その値に基づいて、制御部がガス量制御手段を制御する仕組みとなっている。したがって、合流部に混入されるオフガス量に応じて、ガス量制御手段を通過する燃料ガス量が変化しても、それを抑制する方向にガス量制御手段を調節できる。
【００１３】
実施の形態２
燃料電池の燃料極から排出されたオフガスが連通部に設けられた合流部から燃料ガスに混入されると、合流部下流のガス流量が変化し、連通部内部の圧力も変化する。例えば、オフガス量が増加すると、連通部内部の圧力が高くなり、流路抵抗が大きくなってガス量制御手段を通過する燃料ガス量が減少する。つまり、連通部の圧力変化と燃料ガス量の変化とは対応しており、連通部の圧力変化からガス量制御手段を通過する燃料ガス量の変化を推定することができる。
【００１４】
そこで、本実施の形態に係る固体高分子電解質型燃料電池システムにおいては、前記連通部に圧力検知手段が設置されている。前記圧力検知手段は、連通部内部の圧力を検知し、検知された値は制御部に伝達される。そして、その値に基づいて、制御部がガス量制御手段を制御する仕組みとなっている。したがって、合流部に混入されるオフガス量に応じて、ガス量制御手段を通過する燃料ガス量が変化しても、それを抑制する方向にガス量制御手段を調節できる。
【００１５】
しかも、圧力検知手段の検知した値は、オフガスの組成や燃料ガスの組成にほとんど影響されない。したがって、メタン系ガス、プロパン系ガスなど、様々なガスが使用でき、システムの汎用性が向上する。
【００１６】
実施の形態３
燃料電池の燃料極へ供給された改質ガスは、その中の水素が発電によって消費された後、オフガスとして燃料極から排出される。ここで、発電によって消費される水素量は、発電される電力の電流値から推定することができる。したがって、オフガス中に含まれる水素量も電流値から推定でき、結果として、発電される電力の電流値からオフガス流量を推定することができる。
【００１７】
そこで、本実施の形態に係る固体高分子電解質型燃料電池システムにおいては、前記固体高分子電解質型燃料電池によって発電される電力の電流値を検知する電流検知手段が設置されている。検知された値は制御部に伝達され、その値に基づいて、制御部がガス量制御手段を制御する仕組みとなっている。したがって、合流部に混入されるオフガス量に応じて、ガス量制御手段を通過する燃料ガス量が変化しても、燃料電池によって発電される電力の電流値に基づいて、燃料ガス量の変化を抑制する方向にガス量制御手段を調節できる。
しかも、電流検知手段は簡便に構成することができるので、システムの低コスト化を図ることもできる。
【００１８】
【実施例】
以下、本発明を実施例に基づいて図面を参照しながら説明する。
《実施例１》
図１は、本発明の実施例１に係る固体高分子電解質型燃料電池システムの構成を示す図である。図１において、図４で示した従来の固体高分子電解質型燃料電池システムのものと同じ機能を有するものについては、同一符号を付与している。また、それらの機能の詳細も、図４で示した従来の固体高分子電解質型燃料電池システムと同様である。
【００１９】
本システムの連通部１１には、燃焼部６の側から順次、合流部１２、ガス量制御弁７’およびガス量検知手段１０を設けている。そして、合流部１２には、燃料極３から排出されるオフガスＧ’を導入する。ガス量制御弁７’およびガス量検知手段１０は、それぞれ信号線１４、１４’によって制御部１３と接続している。
【００２０】
次に、所定の燃料ガスＦを、ガス量検知手段１０、ガス量制御弁７’および合流部１２を経由して燃焼部６に供給した。このとき、燃料極３から排出されたオフガスＧ’を、連通部１１に設けられた合流部１２から燃料ガスＦに混入させ、一緒に燃焼部６に供給した。また、ガス量制御弁７’を通過する燃料ガス量をガス量検知手段１０でリアルタイムで検知した。さらに、検知した値が信号線１４’を通って制御部１３に伝達され、その値に基づいた命令が信号線１４を通ってガス量制御弁７’に伝達され、弁の開度が調節されるようにした。そして、燃料電池を所定の負荷に接続した。
【００２１】
その結果、電力負荷の増減などによってオフガスＧ’の量が変化し、合流部１２の下流のガス流量は逐次変化した。しかし、流路抵抗が大きくなると、ガス量制御弁７’の開度が大きくなってそれを通過する燃料ガス量が増加し、流路抵抗が小さくなると、ガス量制御弁７’の開度が小さくなってそれを通過する燃料ガス量が減少した。そして、燃焼部６の燃焼状態は、常に安定であった。また、システムの運転効率も良好であった。
【００２２】
《実施例２》
図２は、本発明の実施例２に係る固体高分子電解質型燃料電池システムの構成を示す図である。ガス量検知手段およびその制御部を設けず、連通部１１に圧力検知手段２０を設け、圧力検知手段２０の検出値に基づいてガス量制御弁７’を制御する制御部２１を設けたこと以外、実施例１と同様の構成とし、同様の操作でシステムを運転した。
【００２３】
すなわち、燃料極３から排出されたオフガスＧ’を連通部１１に設けられた合流部１２から燃料ガスＦに混入し、燃焼部６に供給した。その際、連通部１１の圧力を圧力検知手段２０によってリアルタイムで検知した。また、検知した値が信号線１４’を通って制御部２１に伝達され、その値に基づいた命令が信号線１４を通ってガス量制御弁７’に伝達され、弁の開度が調節されるようにした。そして、燃料電池を所定の負荷に接続した。
【００２４】
その結果、電力負荷の増減などによってオフガスＧ’の量が変化し、合流部１２の下流の圧力は逐次変化した。しかし、圧力が高くなると、ガス量制御弁７’の開度が大きくなってそれを通過する燃料ガス量が増加し、圧力が低くなると、ガス量制御弁７’の開度が小さくなってそれを通過する燃料ガス量が減少した。そして、燃焼部６の燃焼状態は、常に安定であった。また、システムの運転効率も良好であった。
さらに、メタン系ガス、プロパン系ガスなど、様々な燃料ガスで前記システムの運転を行ったところ、何れの場合も安定した運転が可能であった。このことから、本システムは汎用性が高いことが示された。
【００２５】
《実施例３》
図３は、本発明の実施例３に係る固体高分子電解質型燃料電池システムの構成を示す図である。
燃焼量検知手段１０および制御部１３を設けず、燃料電池１の電力負荷への出力端３０、３０’のうち、一方の出力端３０’に固定抵抗３１を設け、固定抵抗３１の両端の電圧から電流値を検知する電流検知手段３２と、前記電流検知手段３２の検知した値に基づいてガス量制御弁７’の開度を制御する制御部３３とを設けたこと以外、実施例１と同様の構成とし、同様の操作でシステムを運転した。
【００２６】
すなわち、燃料極３から排出されたオフガスＧ’を連通部１１に設けられた合流部１２から燃料ガスＦに混入し、燃焼部６に供給した。その際、燃料電池によって発電された電力の電流値を、電流検知手段３２によってリアルタイムで検知した。また、検知した値が信号線１４を通って制御部３３に伝達され、その値に基づいた命令が信号線１４’を通ってガス量制御弁７’に伝達され、弁の開度が調節されるようにした。そして、燃料電池を所定の負荷に接続した。
【００２７】
その結果、電流値は逐次変化したが、その値に基づいてガス量制御弁７’の開度が調節されるようになっているため、燃焼部６の燃焼状態は、常に安定であった。
また、電流検知手段３２は、出力端３０に設けた固定抵抗３１の電圧を測定するためだけの簡便なものを設置したので、システム全体としては、実施例１、２に比べて低コストであった。
【００２８】
【発明の効果】
本発明によれば、水素を含むオフガスを外部に排出することなく燃焼部に供給することができるため、運転効率が向上する。また、燃焼部の燃焼状態を安定に維持することができる。しかも、圧力検知手段を用いたシステムによれば、メタン系ガス、プロパン系ガスなど、様々な燃料ガスが使用でき、システムの汎用性が向上する。また、電流検知手段を用いたシステムによれば、システムの低コスト化を図ることができる。
【図面の簡単な説明】
【図１】本発明の実施例１の固体高分子電解質型燃料電池システムの構成を示す図である。
【図２】本発明の実施例２の固体高分子電解質型燃料電池システムの構成を示す図である。
【図３】本発明の実施例３の固体高分子電解質型燃料電池システムの構成を示す図である。
【図４】従来の固体高分子電解質型燃料電池システムの構成を示す図である。
【符号の説明】
１固体高分子電解質型燃料電池
２空気極
３燃料極
４ファン
５改質器
６燃焼部
７ガス量制御手段
７’ガス量制御弁
１０ガス量検知手段
１１連通部
１２合流部
１３、２１、３３制御部
１４、１４’信号線
２０圧力検知手段
３０、３０’出力端
３１固定抵抗
３２電流検知手段
Ａ酸化剤ガス
Ａ’残りのガス
Ｇ改質ガス
Ｇ’オフガス
Ｘ原料ガス
Ｙ原料水
Ｆ燃料ガス[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid polymer electrolyte fuel cell system that uses an off-gas discharged from a fuel electrode of a solid polymer electrolyte fuel cell as a fuel gas.
[0002]
[Prior art]
A conventional solid polymer electrolyte fuel cell system is shown in FIG. In FIG. 4, reference numeral 1 denotes a solid polymer electrolyte fuel cell, which is generally composed of an air electrode 2 and a fuel electrode 3 sandwiching a solid polymer electrolyte membrane. The upstream side of the air electrode 2 communicates with a fan 4 that supplies, for example, air as the oxidant gas A. The supplied air flows toward a downstream side through a predetermined passage in contact with the air electrode 2. At this time, a required amount of oxygen in the air is consumed by the electrode reaction, and the remaining gas A ′ is discharged to the outside.
[0003]
On the other hand, the upstream side of the fuel electrode 3 communicates with the reformer 5. Then, the raw material gas X such as natural gas and the raw water Y necessary for the steam reforming reaction are supplied to the reformer 5. The reformer 5 includes a combustion unit 6 for heating itself. Fuel gas F is supplied to the combustion unit 6 from the gas amount control means 7 through the communication unit 11. As the gas amount control means 7, a control valve or the like is generally used. When the fuel gas F burns in the combustion unit 6, the reformer 5 is heated to a predetermined temperature. At this time, in the reformer 5, a reaction between the raw material gas X and the raw material water Y occurs, and a hydrogen-rich reformed gas G is generated.
[0004]
The reformed gas G is supplied to the fuel electrode 3 and flows through a predetermined passage in contact with the fuel electrode 3 toward the downstream side. At this time, only a necessary amount of hydrogen in the reformed gas G is consumed in the electrode reaction, and the remaining gas is discharged to the outside as an off-gas G ′. That is, after a part of hydrogen is consumed by power generation, off-gas G ′ containing hydrogen is discharged to the outside from the downstream side of the fuel electrode 3.
[0005]
[Problems to be solved by the invention]
In the conventional solid polymer electrolyte fuel cell system, as described above, off-gas containing hydrogen is discharged to the outside. Therefore, there is a problem that the operation efficiency of the fuel cell system is low. Further, when the off gas is discharged to the outside, hydrogen in the off gas may be mixed with the surrounding air to become a combustible gas. Therefore, development of a highly efficient and highly safe solid polymer electrolyte fuel cell system in which hydrogen does not flow out is desired.
[0006]
[Means for Solving the Problems]
In the present invention, in order to solve the above problem, a merging portion for joining off-gas G ′ discharged from the fuel electrode is provided in the communication portion 11 connecting the combustion portion 6 and the gas amount control means 7. . A predetermined control unit for controlling the gas amount control means is provided.
That is, the present invention relates to a reformer that generates a reformed gas from a raw material gas, and a solid polymer electrolyte fuel cell that generates power using the reformed gas and the oxidant gas obtained by the reformer, A combustion unit for heating the reformer, a gas amount control valve for adjusting an amount of fuel gas supplied to the combustion unit, and a communication unit that connects the gas amount control valve and the combustion unit. And a merging portion for joining off gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communicating portion, and a control portion for controlling the amount of fuel gas passing through the gas amount control valve , The controller increases the opening amount of the gas amount control valve when the flow passage resistance inside the communication portion increases, and increases the opening amount of the gas amount control valve when the flow passage resistance inside the communication portion decreases. The present invention relates to a solid polymer electrolyte fuel cell system to be reduced .
[0007]
The present invention also provides a reformer that generates a reformed gas from a raw material gas, and a solid polymer electrolyte fuel cell that generates electric power using the reformed gas and the oxidant gas obtained by the reformer. A combustion unit for heating the reformer, a gas amount control valve for adjusting an amount of fuel gas supplied to the combustion unit, and a communication unit that connects the gas amount control valve and the combustion unit. A joining portion for joining off gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communicating portion, a gas amount detecting means for detecting a fuel gas amount passing through the gas amount control valve , and A control unit that controls the gas amount control valve based on a value detected by a gas amount detection unit , wherein the control unit mixes the off-gas into the fuel gas inside the communication unit from the junction, When the gas is supplied to the combustion section together with the gas, the communication section When the flow resistance of the gas passage increases and the amount of fuel gas detected by the gas amount detection means decreases, the opening of the gas amount control valve increases, the flow resistance in the communication portion decreases, and the gas The present invention relates to a solid polymer electrolyte fuel cell system that reduces the opening of the gas amount control valve when the amount of fuel gas detected by the amount detecting means increases .
[0008]
The present invention also provides a reformer that generates a reformed gas from a raw material gas, and a solid polymer electrolyte fuel cell that generates electric power using the reformed gas and the oxidant gas obtained by the reformer. A combustion unit for heating the reformer, a gas amount control valve for adjusting an amount of fuel gas supplied to the combustion unit, and a communication unit that connects the gas amount control valve and the combustion unit. The off-gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell is joined to the communication part, the pressure detection means for detecting the pressure inside the communication part, and the pressure detection means A control unit that controls the gas amount control valve based on a value, and the control unit mixes the off-gas from the merging unit into the fuel gas inside the communication unit and supplies the fuel gas together with the fuel gas to the combustion unit. Is detected by the pressure detection means. When the pressure increases, increasing the opening of the gas control valve, has been when the pressure decreases detected by the pressure detecting means, a solid polymer electrolyte fuel cell system to reduce the opening of the gas control valve .
[0009]
The present invention also provides a reformer that generates a reformed gas from a raw material gas, and a solid polymer electrolyte fuel cell that generates electric power using the reformed gas and the oxidant gas obtained by the reformer. A combustion unit for heating the reformer, a gas amount control valve for adjusting an amount of fuel gas supplied to the combustion unit, and a communication unit that connects the gas amount control valve and the combustion unit. And a current detection unit that detects a current value of electric power generated by the solid polymer electrolyte fuel cell, and a junction unit that joins off-gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communication unit. And a control unit that controls the gas amount control valve based on a value detected by the current detection unit , wherein the control unit mixes the off-gas from the junction into the fuel gas inside the communication unit. And supplied to the combustion section together with the fuel gas When the amount of off gas estimated from the current detected by the current detection means increases, the opening of the gas amount control valve is increased, and when the amount of off gas estimated from the current detected by the current detection means decreases. The present invention relates to a solid polymer electrolyte fuel cell system that reduces the opening of the gas amount control valve . As the raw material gas, a hydrocarbon-based raw material gas is mainly used.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the fuel cell system of the present invention, the off-gas discharged from the fuel electrode is mixed into the fuel gas from the merging portion provided in the communication portion connecting the combustion portion and the gas amount control means, and is supplied to the combustion portion together with the fuel gas. The As a result, the operating efficiency of the system is increased.
However, since the gas flow rate downstream of the merging portion increases due to the mixing of the off-gas, the flow path resistance increases and the amount of fuel gas that passes through the control means decreases. Also, the amount of off-gas varies depending on various factors such as fluctuations in the load connected to the solid polymer electrolyte fuel cell.
[0011]
Therefore, in the fuel cell system of the present invention, a control unit for controlling the amount of fuel gas passing through the gas amount control means is provided. The gas amount control means is controlled based on the value detected by the predetermined detection means.
Therefore, even if the amount of off-gas mixed in the merging portion changes due to, for example, a change in the power load connected to the fuel cell, the amount of fuel gas supplied to the combustion portion can be maintained within a predetermined range. The part can be maintained in a stable state.
[0012]
Embodiment 1
When the off gas discharged from the fuel electrode of the fuel cell is mixed into the fuel gas from the merging portion provided in the communicating portion, the gas flow rate downstream of the merging portion changes due to the mixing of the off gas, and the flow path resistance also changes. Therefore, the amount of fuel gas that passes through the gas amount control means also changes.
Therefore, in the solid polymer electrolyte fuel cell system according to the present embodiment, the gas amount detection means is installed upstream or downstream of the gas amount control means. The gas amount detection means detects the amount of fuel gas passing through the gas amount control means, and the detected value is transmitted to the control unit. Based on the value, the control unit controls the gas amount control means. Therefore, even if the amount of fuel gas passing through the gas amount control means changes according to the amount of off-gas mixed into the junction, the gas amount control means can be adjusted in a direction to suppress it.
[0013]
Embodiment 2
When the off gas discharged from the fuel electrode of the fuel cell is mixed into the fuel gas from the joining portion provided in the communicating portion, the gas flow rate downstream of the joining portion changes, and the pressure inside the communicating portion also changes. For example, when the amount of off-gas increases, the pressure inside the communication portion increases, the flow path resistance increases, and the amount of fuel gas that passes through the gas amount control means decreases. That is, the change in pressure at the communication portion corresponds to the change in the amount of fuel gas, and the change in the amount of fuel gas passing through the gas amount control means can be estimated from the change in pressure at the communication portion.
[0014]
Therefore, in the solid polymer electrolyte fuel cell system according to the present embodiment, pressure detecting means is installed in the communication portion. The pressure detection means detects the pressure inside the communication part, and the detected value is transmitted to the control part. Based on the value, the control unit controls the gas amount control means. Therefore, even if the amount of fuel gas passing through the gas amount control means changes according to the amount of off-gas mixed into the junction, the gas amount control means can be adjusted in a direction to suppress it.
[0015]
In addition, the value detected by the pressure detection means is hardly influenced by the composition of the off gas and the composition of the fuel gas. Therefore, various gases such as methane gas and propane gas can be used, and the versatility of the system is improved.
[0016]
Embodiment 3
The reformed gas supplied to the fuel electrode of the fuel cell is discharged from the fuel electrode as off-gas after hydrogen in the reformed gas is consumed by power generation. Here, the amount of hydrogen consumed by power generation can be estimated from the current value of the generated power. Therefore, the amount of hydrogen contained in the offgas can also be estimated from the current value, and as a result, the offgas flow rate can be estimated from the current value of the generated power.
[0017]
Therefore, in the solid polymer electrolyte fuel cell system according to the present embodiment, current detection means for detecting the current value of the electric power generated by the solid polymer electrolyte fuel cell is installed. The detected value is transmitted to the control unit, and based on the value, the control unit controls the gas amount control means. Therefore, even if the amount of fuel gas passing through the gas amount control means changes according to the amount of off-gas mixed into the junction, the change in the amount of fuel gas is based on the current value of the power generated by the fuel cell. The gas amount control means can be adjusted in the suppressing direction.
Moreover, since the current detection means can be simply configured, the cost of the system can be reduced.
[0018]
【Example】
Hereinafter, the present invention will be described based on examples with reference to the drawings.
Example 1
FIG. 1 is a diagram showing a configuration of a solid polymer electrolyte fuel cell system according to Embodiment 1 of the present invention. 1, those having the same functions as those of the conventional solid polymer electrolyte fuel cell system shown in FIG. 4 are given the same reference numerals. The details of these functions are also the same as those of the conventional solid polymer electrolyte fuel cell system shown in FIG.
[0019]
In the communication part 11 of the present system, a merging part 12, a gas quantity control valve 7 ', and a gas quantity detection means 10 are provided in this order from the combustion part 6 side. Then, off-gas G ′ discharged from the fuel electrode 3 is introduced into the junction 12. The gas amount control valve 7 ′ and the gas amount detection means 10 are connected to the control unit 13 by signal lines 14 and 14 ′, respectively.
[0020]
Next, a predetermined fuel gas F was supplied to the combustion unit 6 via the gas amount detection means 10, the gas amount control valve 7 ′, and the merging unit 12. At this time, off-gas G ′ discharged from the fuel electrode 3 was mixed into the fuel gas F from the merging portion 12 provided in the communication portion 11 and supplied to the combustion portion 6 together. Further, the amount of fuel gas passing through the gas amount control valve 7 ′ was detected by the gas amount detection means 10 in real time. Further, the detected value is transmitted to the control unit 13 through the signal line 14 ′, and a command based on the value is transmitted to the gas amount control valve 7 ′ through the signal line 14 to adjust the opening of the valve. It was to so. The fuel cell was connected to a predetermined load.
[0021]
As a result, the amount of off-gas G ′ changed due to increase / decrease in the power load, and the gas flow rate downstream of the merging portion 12 changed sequentially. However, when the flow path resistance increases, the opening amount of the gas amount control valve 7 ′ increases, the amount of fuel gas passing therethrough increases, and when the flow path resistance decreases, the opening amount of the gas amount control valve 7 ′ increases. The amount of fuel gas passing through it decreased. And the combustion state of the combustion part 6 was always stable. Moreover, the operating efficiency of the system was also good.
[0022]
Example 2
FIG. 2 is a diagram showing a configuration of a solid polymer electrolyte fuel cell system according to Embodiment 2 of the present invention. Other than not providing the gas amount detection means and its control unit, providing the pressure detection means 20 in the communication unit 11 and providing the control unit 21 for controlling the gas amount control valve 7 ′ based on the detection value of the pressure detection means 20. The configuration was the same as in Example 1, and the system was operated with the same operation.
[0023]
That is, off-gas G ′ discharged from the fuel electrode 3 was mixed into the fuel gas F from the junction 12 provided in the communication part 11 and supplied to the combustion part 6. At that time, the pressure of the communication portion 11 was detected by the pressure detection means 20 in real time. Further, the detected value is transmitted to the control unit 21 through the signal line 14 ′, and a command based on the value is transmitted to the gas amount control valve 7 ′ through the signal line 14 to adjust the opening of the valve. It was to so. The fuel cell was connected to a predetermined load.
[0024]
As a result, the amount of off-gas G ′ changed due to increase / decrease in the power load and the pressure downstream of the merging portion 12 changed sequentially. However, when the pressure increases, the opening amount of the gas amount control valve 7 ′ increases and the amount of fuel gas passing therethrough increases. When the pressure decreases, the opening amount of the gas amount control valve 7 ′ decreases and decreases. The amount of fuel gas passing through has decreased. And the combustion state of the combustion part 6 was always stable. Moreover, the operating efficiency of the system was also good.
Furthermore, when the system was operated with various fuel gases such as methane gas and propane gas, stable operation was possible in any case. From this, it was shown that this system is highly versatile.
[0025]
Example 3
FIG. 3 is a diagram showing a configuration of a solid polymer electrolyte fuel cell system according to Example 3 of the present invention.
Without providing the combustion amount detection means 10 and the control unit 13, a fixed resistor 31 is provided at one output end 30 ′ of the output ends 30, 30 ′ to the power load of the fuel cell 1, and a voltage across the fixed resistor 31 is provided. Example 1 except that a current detection unit 32 for detecting a current value from the current detection unit 32 and a control unit 33 for controlling the opening of the gas amount control valve 7 ′ based on the value detected by the current detection unit 32 are provided. The system was operated with the same configuration and the same operation.
[0026]
That is, off-gas G ′ discharged from the fuel electrode 3 was mixed into the fuel gas F from the junction 12 provided in the communication part 11 and supplied to the combustion part 6. At that time, the current value of the electric power generated by the fuel cell was detected by the current detection means 32 in real time. Further, the detected value is transmitted to the control unit 33 through the signal line 14, and a command based on the value is transmitted to the gas amount control valve 7 'through the signal line 14', and the opening degree of the valve is adjusted. It was to so. The fuel cell was connected to a predetermined load.
[0027]
As a result, although the current value changed sequentially, the opening of the gas amount control valve 7 ′ was adjusted based on the value, so that the combustion state of the combustion section 6 was always stable.
In addition, since the current detection means 32 is installed simply for measuring the voltage of the fixed resistor 31 provided at the output end 30, the overall system is less expensive than the first and second embodiments. It was.
[0028]
【The invention's effect】
According to the present invention, since the off gas containing hydrogen can be supplied to the combustion section without being discharged to the outside, the operation efficiency is improved. Moreover, the combustion state of the combustion part can be maintained stably. Moreover, according to the system using the pressure detecting means, various fuel gases such as methane gas and propane gas can be used, and the versatility of the system is improved. Moreover, according to the system using the current detection means, the cost of the system can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a solid polymer electrolyte fuel cell system of Example 1 of the present invention.
FIG. 2 is a diagram showing a configuration of a solid polymer electrolyte fuel cell system according to Example 2 of the present invention.
FIG. 3 is a diagram showing a configuration of a solid polymer electrolyte fuel cell system according to Example 3 of the present invention.
FIG. 4 is a diagram showing a configuration of a conventional solid polymer electrolyte fuel cell system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solid polymer electrolyte type fuel cell 2 Air electrode 3 Fuel electrode 4 Fan 5 Reformer 6 Combustion part 7 Gas quantity control means 7 'Gas quantity control valve 10 Gas quantity detection means 11 Communication part 12 Merge parts 13, 21, 33 Control section 14, 14 'signal line 20 Pressure detection means 30, 30' output end 31 Fixed resistance 32 Current detection means A Oxidant gas A 'remaining gas G reformed gas G' off gas X raw material gas Y raw material water F fuel gas

Claims

A reformer that generates a reformed gas from a raw material gas, a solid polymer electrolyte fuel cell that generates power using the reformed gas and the oxidant gas obtained by the reformer, and the reformer A combustion unit for heating, a gas amount control valve for adjusting the amount of fuel gas supplied to the combustion unit, and a communication unit connecting the gas amount control valve and the combustion unit,
A merging portion for merging the off-gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communicating portion; and a control portion for controlling the amount of fuel gas passing through the gas amount control valve ;
When the off-gas is mixed into the fuel gas inside the communication portion from the merge portion and supplied to the combustion portion together with the fuel gas, the control portion increases the flow resistance inside the communication portion. A solid polymer electrolyte fuel cell system which reduces the opening of the gas amount control valve when the opening of the amount control valve is increased and the flow path resistance inside the communication portion is reduced .

A reformer that generates a reformed gas from a raw material gas, a solid polymer electrolyte fuel cell that generates power using the reformed gas and the oxidant gas obtained by the reformer, and the reformer A combustion unit for heating, a gas amount control valve for adjusting the amount of fuel gas supplied to the combustion unit, and a communication unit connecting the gas amount control valve and the combustion unit,
A merging portion for joining off gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communicating portion; a gas amount detecting means for detecting an amount of fuel gas passing through the gas amount control valve ; and the gas amount A control unit for controlling the gas amount control valve based on the value detected by the detection means ,
When the off-gas is mixed into the fuel gas inside the communication part from the junction part and supplied to the combustion part together with the fuel gas, the control part increases the flow resistance inside the communication part, and the gas When the amount of fuel gas detected by the amount detection means decreases, the opening of the gas amount control valve increases, the flow resistance inside the communication portion decreases, and the amount of fuel gas detected by the gas amount detection means increases. If it becomes, the polymer electrolyte fuel cell system which makes the opening degree of the said gas quantity control valve small .

A reformer that generates a reformed gas from a raw material gas, a solid polymer electrolyte fuel cell that generates power using the reformed gas and the oxidant gas obtained by the reformer, and the reformer A combustion unit for heating, a gas amount control valve for adjusting the amount of fuel gas supplied to the combustion unit, and a communication unit connecting the gas amount control valve and the combustion unit,
A merge part for joining off-gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communication part, a pressure detection means for detecting the pressure inside the communication part, and a value detected by the pressure detection means based and a control unit for controlling the gas amount control valve,
When the pressure detected by the pressure detection means increases when the off gas is mixed into the fuel gas inside the communication part from the junction and supplied to the combustion part together with the fuel gas, A solid polymer electrolyte fuel cell system in which the opening of the gas amount control valve is reduced when the opening amount of the gas amount control valve is increased and the pressure detected by the pressure detecting means is reduced .

A reformer that generates a reformed gas from a raw material gas, a solid polymer electrolyte fuel cell that generates power using the reformed gas and the oxidant gas obtained by the reformer, and the reformer A combustion unit for heating, a gas amount control valve for adjusting the amount of fuel gas supplied to the combustion unit, and a communication unit connecting the gas amount control valve and the combustion unit,
A merging portion for joining off-gas discharged from the fuel electrode of the solid polymer electrolyte fuel cell to the communicating portion; and a current detecting means for detecting a current value of electric power generated by the solid polymer electrolyte fuel cell; A control unit for controlling the gas amount control valve based on a value detected by the current detection means ,
The control unit is configured to estimate the off gas estimated from the current detected by the current detection unit when the off gas is mixed into the fuel gas inside the communication unit from the junction and supplied to the combustion unit together with the fuel gas. A solid polymer that increases the opening amount of the gas amount control valve when the amount increases, and decreases the opening amount of the gas amount control valve when the off-gas amount estimated from the current detected by the current detection means decreases. Electrolytic fuel cell system.