JP4050919B2

JP4050919B2 - Fuel cell system and operation method thereof

Info

Publication number: JP4050919B2
Application number: JP2002079126A
Authority: JP
Inventors: 伸二宮内; 正高尾関; 照丸原田; 彰成中村
Original assignee: Panasonic Corp; Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Corp; Panasonic Holdings Corp
Priority date: 2002-03-20
Filing date: 2002-03-20
Publication date: 2008-02-20
Anticipated expiration: 2022-03-20
Also published as: JP2003282108A

Description

【０００１】
【発明の属する技術分野】
本発明は、燃料電池を用いて発電と排熱の回収を行う燃料電池システムに関する。
【０００２】
【従来の技術】
従来の燃料電池を用いた発電装置について、図５を参照しながら説明する。
この発電装置は、燃料電池１、天然ガスなどの原料を水蒸気改質し、水素を主成分とするガスを生成して燃料電池１に供給する燃料処理装置２、および酸化剤の空気を燃料電池１に供給するための空気供給装置６を有する。燃料処理装置２は、改質ガスを生成する改質器３と、改質ガスに含まれる一酸化炭素を水と反応させ二酸化炭素と水素にするための一酸化炭素変成器４からなる。燃料電池１と燃料処理装置２の間には、燃料電池１に供給する燃料ガスを加湿する燃料加湿器５が備えられ、空気供給装置６と燃料電池１との間には、供給する空気を加湿する酸化側加湿器７が備えられている。燃料電池１には、発電により生じた熱を回収する冷却水を循環させる冷却配管８が接続され、冷却配管８には、冷却配管８内の冷却水を熱交換器１０に通すポンプ９が設けられている。熱交換器１０に排熱回収配管１２が接続され、冷却水が回収した熱を貯湯タンク１３内の水に移動させる。排熱回収配管１２は、一端が貯湯タンク１３の上部に、他端が貯湯タンク１３の底部に接続され、循環ポンプ１１により、貯湯タンク内の底面近くの水を熱交換器１０を通して貯湯タンク１３の上部に戻す。
【０００３】
従来の燃料電池システムの動作について説明する。
燃料処理装置２は、天然ガスなどの原料を水蒸気改質し、水素を主成分とするガスを生成する。そして、このガスは、燃料側加湿器５で加湿された後、燃料電池１に供給される。一方、空気供給装置６により、酸化剤ガスは酸化側加湿器７で加湿され、燃料電池１に供給される。燃料電池１は、上記のようにして供給される燃料と酸化剤とを反応させて発電する。
燃料電池１は、発電と同時に熱を発生する。この熱は、冷却配管８内の冷却水に回収され、ポンプ９により熱交換器１０へ供給される。そして、この熱は熱交換器１０より排熱回収配管１２を経由し、貯湯タンク１３へ回収される。排熱回収配管１２内の水の流量は、燃料電池１の発電量に応じて増減する。
【０００４】
【発明が解決しようとする課題】
上記のような従来の構成では、熱交換器１０において、熱交換時の水蒸気や気泡の発生などにより排熱回収配管１２内の圧力損失に変化が生じる。一方、発電量が低下する場合は、貯湯タンク１３の水を高温で維持するために、循環ポンプ１１の出力を低下させて、排熱回収配管１２内の水の流量を低下させることが必要となる。この場合にも、水蒸気、気泡の発生および気泡の滞留などにより排熱回収配管１２内の圧力損失が増加し、流量変動が起こりやすくなる。
【０００５】
排熱回収配管１２は、市水が循環するため、配管中のごみや錆等の詰まり等により配管内の圧力損失が増加する可能性がある。このような場合、循環ポンプ１１の出力を増大させても、流量は増加せず、熱が充分に回収されないため、冷却配管８内の冷却水の温度が上昇し、燃料電池１の発電に支障をきたすという問題点がある。
また、循環ポンプ１１の故障や排熱回収配管１２の詰まり、漏れ、排熱回収不良等による異常を常時監視し、異常時には速やかに対処できることが望まれている。
【０００６】
さらに、排熱回収配管１２内のごみや錆等による詰まり等によって圧力損失が増加し、排熱回収配管１２内の水の流量が低下するのを避けるため、循環ポンプ１１の出力を一定値以上に保つように制御することが考えられる。しかし、このように制御すると、貯湯タンク１３へ送られる水の温度が低下するため、貯湯タンク１３内上層部の水の温度が低下する。よって、貯湯タンク１３内の水が全量沸き上がらなければ、給湯利用できないなど利便性が損なわれるという問題点がある。
【０００７】
本発明は、上記の従来の課題を解決するため、燃料電池で発生した熱を回収する冷却配管と熱交換する排熱回収配管の圧力損失による燃料電池の異常な温度上昇がなく、高温の水を安定して供給することができる燃料電池システムを提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明の燃料電池システムは、燃料ガスおよび酸化剤ガスを用いて電力と熱を発生させる燃料電池と、燃料電池で発生した熱を回収するための冷却水を循環させる冷却配管と、外部給湯負荷に供給するための湯水を貯える貯湯タンクと、前記冷却水が回収した熱を前記貯湯タンク内の水に移動させる熱交換器と、一端が前記貯湯タンクの上部に、他端が貯湯タンクの底部にそれぞれ連結され、前記貯湯タンク内の水を前記熱交換器に循環させる排熱回収配管と、排熱回収配管に設けられ、貯湯タンク内の水を熱交換器を通して貯湯タンクに戻す循環ポンプと、前記燃料電池の温度または前記冷却水の温度を検出する電池温度検出器と、前記循環ポンプの出力を制御する制御装置とを備え、前記制御装置は、前記電池温度検出器により検出された温度が、前記燃料電池の温度上昇によって運転停止動作が行われる第１の所定温度よりも低い第２の所定温度未満の場合、前記燃料電池の発電量に応じて前記循環ポンプの出力を制御し、前記電池温度検出器により検出された温度が前記第２の所定温度以上になった場合、前記循環ポンプの出力を強制的に所定値以上に制御することを特徴とする。
【０００９】
また、本発明は、燃料ガスおよび酸化剤ガスを用いて電力と熱を発生させる燃料電池と、燃料電池で発生した熱を回収するための冷却水を循環させる冷却配管と、外部給湯負荷に供給するための湯水を貯える貯湯タンクと、前記冷却水が回収した熱を前記貯湯タンク内の水に移動させる熱交換器と、一端が前記貯湯タンクの上部に、他端が貯湯タンクの底部にそれぞれ連結され、前記貯湯タンク内の水を前記熱交換器に循環させる排熱回収配管と、排熱回収配管に設けられ、貯湯タンク内の水を熱交換器を通して貯湯タンクに戻す循環ポンプと、前記燃料電池の温度または前記冷却水の温度を検出する電池温度検出器と、を備える燃料電池システムの運転方法であって、前記電池温度検出器により検出された温度が、前記燃料電池の温度上昇によって運転停止動作が行われる第１の所定温度よりも低い第２の所定温度未満の場合、前記燃料電池の発電量に応じて前記循環ポンプの出力を制御し、前記電池温度検出器により検出された温度が前記第２の所定温度以上になった場合、前記循環ポンプの出力を強制的に所定値以上に制御することを特徴とする。
【００１０】
【発明の実施の形態】
以下、本発明の実施の形態を、図面を参照しながら説明する。
【００１１】
《実施例１》
図１は本発明の実施例１における燃料電池システムの構成図である。
図１において、図５で示した従来の燃料電池システム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おり、それらの機能の詳細は、図５のものに準ずるものとして説明を省略する。
【００１２】
１４は、燃料電池１より生じた熱を回収する冷却水の温度を検出するサーミスタ等の電池温度検出器であり、冷却配管８の燃料電池１からの出口側に設置されている。１５は、電池温度検出器１４が検出する冷却水の温度が運転温度の上限値未満の時は、燃料電池１の発電量に応じて排熱回収配管１２内の水の流量が所定流量になるように循環ポンプ１１の出力を制御し、この温度が運転温度の上限値以上になると燃料電池１の発電量に関係なく循環ポンプ１１の出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する制御装置である。
【００１３】
次に動作および作用について説明する。
燃料電池システムの運転時には、燃料処理装置２は天然ガスなどの原料を水蒸気改質し、水素を主成分とするガスを生成して燃料電池１に供給する。また、空気供給装置６により、酸化剤ガスは酸化側加湿器７で加湿され、燃料電池１に供給される。一方、燃料電池１の発電により生じた熱は、冷却配管８内を流れる冷却水に回収される。冷却水はポンプ９により循環し、冷却水に回収された熱は、熱交換器１０を介して排熱回収配管１２内を循環する水に移動する。
【００１４】
制御装置１５は、電池温度検出器１４が検出する冷却水の温度が運転温度の上限値未満であるときは、燃料電池１の発電量に応じて熱回収配管１２内の水の流量が所定流量となるように循環ポンプ１１の出力を制御する。
また、制御装置１５は、冷却水の温度が運転温度の上限値以上になると、循環ポンプの出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する。
【００１５】
例えば、高分子電解質型燃料電池を用いて、７０〜８５℃で通常運転している場合であれば、運転温度が上限値の９０℃以上になった時、循環ポンプ１１の出力を強制的に増加させ、冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる１００℃付近にまで到達しない値に制御し、かつ迅速に通常運転温度に復帰させる。
【００１６】
このような構成にすることにより、排熱回収配管１２での気泡の発生やごみの詰まり等による圧力損失の増大を防ぐことができ、それにともなう燃料電池１の温度上昇を阻止できる。また、燃料電池１の温度上昇による緊急停止等の運転停止動作をしなくてすむため、長時間に渡り安定した発電を継続できる。
【００１７】
なお、上記実施例では、電池温度検出器１４は、燃料電池１より熱を回収した冷却水の温度を検出する構成としているが、燃料電池１自身の内部または表面温度等を検出する構成としてもよい。
【００１８】
《参考例１》
参考例１は、図１における制御装置１５の機能が実施例１と異なる。
すなわち、参考例１における制御装置１５は以下のような機能を有する。
循環ポンプ１１の出力の単位時間当たりの変化をΔＷとし、電池温度検出器１４が検出する冷却水温度の単位時間当たりの変化をΔＴとする。この循環ポンプ１１の出力変化ΔＷと冷却水の温度変化ΔＴの比ΔＴ／ΔＷは、燃料電池１の通常運転時には、一定範囲内に収まる。しかし、排熱回収配管１２内の気泡の発生やゴミの詰まり等により圧力損失が増大し、冷却水温度が上昇すると、ΔＴ／ΔＷ値は通常運転時の上限値を超える。このようにΔＴ／ΔＷが、通常運転時の上限値以上である状態がΔＴ／ΔＷが上限値を超えてから冷却水の温度が運転温度の上限値に達する程度の所定時間継続すると、循環ポンプ１１の出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する。また、ΔＴ／ΔＷが通常運転時の下限値以下である状態が、ΔＴ／ΔＷ値が下限値以下となってから冷却水の温度が運転温度の下限値よりも若干高い温度に達する程度の所定時間継続すると、循環ポンプ１１の出力を強制的に運転温度の下限値を下回らない値に制御する。
【００１９】
次に、動作および作用について説明する。
制御装置１５は、燃料電池１の発電量に応じて排熱回収配管１２内の水の流量が所定流量となるように循環ポンプ１１の出力を制御するとともに、電池温度検出器１４が検出する冷却水の温度を監視する。循環ポンプ１１の出力が発電量の増加に応じて連続的に増加するとともに、電池温度検出器１４が検出する冷却水の温度が連続的に上昇する場合がある。この時、上記ΔＴ／ΔＷが通常運転時の上限値以上である状態が、ΔＴ／ΔＷ値が上限値を超えてから冷却水の温度が運転温度の上限値に達する程度の所定時間継続すると、制御装置１５は、循環ポンプ１１の出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する。
【００２０】
また、循環ポンプ１１の出力が発電量の減少に応じて連続的に減少するとともに、排熱回収配管１２内の水の温度が連続的に低下する場合がある。このとき、ΔＴ／ΔＷが通常運転時の下限値以下である状態が、ΔＴ／ΔＷ値が下限値以下となってから冷却水の温度が運転温度の下限値よりも若干高い温度に低下する程度の所定時間継続すると、制御装置１５は、循環ポンプ１１の出力を強制的に冷却水の温度が運転温度の下限値を下回らない値に制御する。
【００２１】
このような構成にすることにより、実施例１と同様の効果が得られるだけでなく、燃料電池１の温度が連続的に低下した時に、循環ポンプ１１の出力を強制的に冷却水の温度が運転温度の下限値を下回らない値に制御しても燃料電池１の温度に変化がなければ、循環ポンプ１１や電池温度検出器１４の故障等のような発電装置における排熱回収系の故障として検出でき、異常発生時には迅速に対処できる。
【００２２】
《参考例２》
図２は本参考例における燃料電池システムの構成図である。
図２において、図１で示した燃料電池システム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おり、それらの機能の説明は省略する。
【００２３】
１７は、熱交換器１０で排熱を回収した排熱回収配管１２内の水の温度を検出するサーミスタ等の排熱回収温度検出器であり、排熱回収配管１２の熱交換器１０からの出口側に設置されている。
１８は、実施例１の制御装置１５と同様に、電池温度検出器１４が検出する冷却水の温度が運転温度の上限値未満の時は、燃料電池１の発電量に応じて排熱回収配管１２内の水の流量が所定流量になるように循環ポンプ１１の出力を制御し、この温度が運転温度の上限値以上になると燃料電池１の発電量に関係なく循環ポンプ１１の出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する機能を有する制御装置である。
【００２４】
また、制御装置１８は、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度がほぼ一定となるように循環ポンプ１１の出力を制御する機能を有する。すなわち、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の上限値と関連した設定温度の上限値以上になると、その温度を下げるために、循環ポンプ１１の出力を上げて、排熱回収配管１２内の水の流量を増加させる。また、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の下限値と関連した設定温度の下限値以下となると、その温度を上げるために循環ポンプ１１の出力を下げて、排熱回収配管１２内の水の流量を減少させる。このようにして、排熱回収配管１２内の水の温度をほぼ一定に維持する。
【００２５】
次に動作および作用について説明する。
制御装置１８は、実施例１と同様に、電池温度検出器１４が検出する冷却水の温度が運転温度の上限値未満の時は、燃料電池１の発電量に応じて排熱回収配管１２内の水の流量が所定流量になるように循環ポンプ１１の出力を制御し、この温度が運転温度の上限値以上になると燃料電池１の発電量に関係なく循環ポンプ１１の出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する。
【００２６】
また、制御装置１８は、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の上限値と関連した設定温度の上限値以上になると、その温度を下げるために、循環ポンプ１１の出力を上げて、排熱回収配管１２内の水の流量を増加させる。また、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の下限値と関連した設定温度の下限値以下になると、その温度を上げるために循環ポンプ１１の出力を下げて、排熱回収配管１２内の水の流量を減少させる。このようにして、排熱回収配管１２内の水の温度をほぼ一定に制御する。
【００２７】
特に、発電量が少ない時には、排熱回収配管１２内の水の流量が低下するため、循環ポンプ１１の出力を低下させて排熱回収配管１２内の水の温度を所定温度に維持する。このとき、排熱回収配管１２での気泡の発生やごみの詰まり等により圧力損失が増加する。しかし、制御装置１８は、気泡の発生やゴミの詰まり等による排熱回収配管１２内の圧力損失の増大により、電池温度が運転温度の上限値以上に上昇した場合に、循環ポンプ１１の出力を強制的に冷却水温度が燃料電池１または冷却配管８に配したポンプ９や電池温度検出器１４等の部材の劣化が激しくなる温度に到達しない値に制御する機能を有している。また、燃料電池の温度上昇による緊急停止等の運転停止動作をしなくてすむため、長時間に渡り安定した発電を継続できる。
【００２８】
なお、本参考例の制御装置は実施例１の制御装置の機能を含んでいるが、その代わりに参考例１の制御装置の機能を具備してもよい。
【００２９】
《参考例３》
図３は本参考例における燃料電池システムの構成図である。
図３において、図２で示した参考例２の燃料電池システム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おり、それらの機能の説明は、省略する。
【００３０】
１９は、循環ポンプ１１の出口側から熱交換器１０の入口側への排熱回収配管１２から分岐し、電磁弁等の弁２０を介して貯湯タンク１３に接続されたバイパス配管である。
２１は、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度がほぼ一定となるように循環ポンプ１１の出力を制御する機能を有する制御装置である。すなわち、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の上限値と関連した設定温度の上限値以上になると、その温度を下げるために、循環ポンプ１１の出力を上げて、排熱回収配管１２内の水の流量を増加させる。また、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の下限値と関連した設定温度の下限値以下になると、その温度を上げるために循環ポンプ１１の出力を下げて、排熱回収配管１２内の水の流量を減少させる。このようにして、排熱回収配管１２内の水の温度をほぼ一定に維持する。
【００３１】
さらに、制御装置２１は、燃料電池の発電量が低下し、電池温度検出器１４が検出する冷却水の温度が運転温度の下限値よりも若干高い温度以下となると、弁２０を開いて、バイパス配管１９を開放する機能を有する。
【００３２】
次に動作および作用について説明する。
制御装置２１は、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の上限値と関連した設定温度の上限値以上になると、温度を下げるために循環ポンプ１１の出力を上げて、排熱回収配管１２内の水の流量を増加させる。また、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の下限値と関連した設定温度の下限値以下になると、その温度を上げるために循環ポンプ１１の出力を下げて、排熱回収配管１２内の水の流量を減少させる。このようにして、排熱回収配管１２内の水の温度をほぼ一定に制御する。
また、発電量が低下し、電池温度検出器１４が検出する冷却水の温度が運転温度の下限値よりも若干高い温度以下になると弁２０を開いて、バイパス配管１９を開放する。
【００３３】
弁２０が開いてバイパス配管１９が開放されると、循環ポンプ１１により供給された水の一部がバイパス配管１９を経由して貯湯タンク１３内に戻るため、熱交換器１０へ供給される水が減少する。従って、発電量が低下した場合でも熱交換器１０により熱を回収した排熱回収配管１２内の水の温度を高温に維持できる。
【００３４】
よって、貯湯タンク１３に高温の水が安定して供給され、貯湯タンク１３内の水が全量沸き上がるまで待たずに、必要量沸き上がった段階で給湯利用できる。
また、本参考例の制御装置の機能と実施例１または参考例１の制御装置の機能とを組み合わせた制御装置を用いてもよい。
なお、上記参考例では、制御装置は、発電量を監視する方法として、電池温度検出器が検出する冷却水の温度を監視する構成としたが、燃料電池の発電量を直接監視する構成としてもよい。
【００３５】
《参考例４》
図４は本参考例における燃料電池システムの構成図である。
図４において、図３で示した参考例３の燃料電池システム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おり、それらの機能の説明は、省略する。
【００３６】
２２は、循環ポンプ１１の出口側から熱交換器１０の入口側への排熱回収配管１２より分岐し、貯湯タンク１３に接続するバイパス配管１９に設けられた弁であり、バイパス配管１９を経由する水の流量を調整することができる。
２３は、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度がほぼ一定となるように循環ポンプ１１の出力を制御する機能を有する制御装置である。すなわち、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の上限値に関連した設定温度の上限値以上になると、その温度を下げるために、循環ポンプ１１の出力を上げて、排熱回収配管１２内の水の流量を増加させる。また、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の下限値と関連した設定温度の下限値以下になると、その温度を上げるために循環ポンプ１１の出力を下げて、排熱回収配管１２内の水の流量を減少させる。このようにして、排熱回収配管１２内の水の温度をほぼ一定に維持する。
【００３７】
また、制御装置２３は、燃料電池１の発電量が低下して、電池温度検出器１４が検出する冷却水の温度が運転温度の下限値よりも若干高い温度以下になると、電池温度検出器１４が検出する冷却水の温度が低くなるにつれて、バイパス配管１９の水の流量が増加するように弁２２を制御する。
【００３８】
次に動作および作用について説明する。
制御装置２３は、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の上限値と関連した設定温度の上限値以上になると、温度を下げるために循環ポンプ１１の出力を上げて、排熱回収配管１２内の水の流量を増加させる。また、排熱回収温度検出器１７が検出する排熱回収配管１２内の水の温度が燃料電池１の運転温度の下限値と関連した設定温度の下限値以下になると、その温度を上げるために循環ポンプ１１の出力を下げて、排熱回収配管１２内の水の流量を減少させる。このようにして、排熱回収配管１２内の水の温度をほぼ一定に制御する。
【００３９】
また、制御装置２３は、燃料電池１の発電量が低下して、電池温度検出器１４が検出する冷却水の温度が運転温度の下限値よりも若干高い温度以下になると、電池温度検出器１４が検出する冷却水の温度が低くなるにつれて、バイパス配管１９の水の流量が増加するように弁２２を制御する。
このとき、循環ポンプ１１により供給された水の一部は、バイパス配管１９を経由して貯湯タンク１３内に戻るため、熱交換器１０へ供給される水の流量が減少する。従って、発電量が低下した場合でも熱交換器１０により熱を回収した水の排熱回収配管１２内の水の温度を高温に維持できる。
【００４０】
よって、貯湯タンク１３に高温の水が安定して供給され、貯湯タンク１３内の水が全量沸き上がるまで待たずに、必要量沸き上がった段階で給湯利用できる。
なお、図１〜４中のポンプ９は、制御装置１５、１８、２１、または２３により発電時に作動するように制御され、作動中は一定に出力される。
【００４１】
【発明の効果】
以上のように、本発明によれば、燃料電池で発生した熱を回収する冷却配管と熱交換する排熱回収配管の圧力損失による燃料電池の異常な温度上昇がなく、高温の水を安定して供給することができる燃料電池システムを提供できる。
【図面の簡単な説明】
【図１】本発明の実施例１および参考例１における燃料電池システムのブロック構成図。
【図２】参考例２における燃料電池システムのブロック構成図。
【図３】参考例３における燃料電池システムのブロック構成図。
【図４】参考例４における燃料電池システムのブロック構成図。
【図５】従来の燃料電池システムのブロック構成図。
【符号の説明】
１燃料電池
２燃料処理装置
３改質器
４一酸化炭素変成器
５燃料加湿器
６空気供給装置
７酸化側加湿器
８冷却配管
９ポンプ
１０熱交換器
１１循環ポンプ
１２排熱回収配管
１３貯湯タンク
１４電池温度検出器
１５、１８、２１、２３制御装置
１７排熱回収温度検出器
１９バイパス配管
２０、２２弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell system that generates power and recovers exhaust heat using a fuel cell.
[0002]
[Prior art]
A power generation apparatus using a conventional fuel cell will be described with reference to FIG.
This power generator includes a fuel cell 1, a fuel treatment device 2 that steam-reforms a raw material such as natural gas, generates a gas mainly containing hydrogen, and supplies the gas to the fuel cell 1, and oxidant air as a fuel cell. 1 has an air supply device 6 for supplying to the air. The fuel processing device 2 includes a reformer 3 that generates reformed gas, and a carbon monoxide converter 4 that reacts carbon monoxide contained in the reformed gas with water to form carbon dioxide and hydrogen. A fuel humidifier 5 is provided between the fuel cell 1 and the fuel processing device 2 to humidify the fuel gas supplied to the fuel cell 1. Between the air supply device 6 and the fuel cell 1, the supplied air is supplied. An oxidation side humidifier 7 for humidifying is provided. The fuel cell 1 is connected to a cooling pipe 8 that circulates cooling water that recovers heat generated by power generation. The cooling pipe 8 is provided with a pump 9 that passes the cooling water in the cooling pipe 8 to the heat exchanger 10. It has been. An exhaust heat recovery pipe 12 is connected to the heat exchanger 10 to move the heat recovered by the cooling water to the water in the hot water storage tank 13. One end of the exhaust heat recovery pipe 12 is connected to the upper part of the hot water storage tank 13 and the other end is connected to the bottom part of the hot water storage tank 13, and the water near the bottom surface in the hot water storage tank is passed through the heat exchanger 10 by the circulation pump 11. Return to the top of.
[0003]
The operation of the conventional fuel cell system will be described.
The fuel processing device 2 steam-reforms a raw material such as natural gas to generate a gas mainly composed of hydrogen. This gas is humidified by the fuel-side humidifier 5 and then supplied to the fuel cell 1. On the other hand, the oxidant gas is humidified by the oxidation side humidifier 7 by the air supply device 6 and supplied to the fuel cell 1. The fuel cell 1 generates power by reacting the fuel and the oxidant supplied as described above.
The fuel cell 1 generates heat simultaneously with power generation. This heat is recovered in the cooling water in the cooling pipe 8 and supplied to the heat exchanger 10 by the pump 9. Then, this heat is recovered from the heat exchanger 10 to the hot water storage tank 13 via the exhaust heat recovery pipe 12. The flow rate of water in the exhaust heat recovery pipe 12 increases or decreases according to the power generation amount of the fuel cell 1.
[0004]
[Problems to be solved by the invention]
In the conventional configuration as described above, in the heat exchanger 10, the pressure loss in the exhaust heat recovery pipe 12 changes due to the generation of water vapor or bubbles during heat exchange. On the other hand, when the power generation amount decreases, in order to maintain the water in the hot water storage tank 13 at a high temperature, it is necessary to decrease the output of the circulation pump 11 and decrease the flow rate of the water in the exhaust heat recovery pipe 12. Become. Also in this case, the pressure loss in the exhaust heat recovery pipe 12 increases due to the generation of water vapor, bubbles, and the retention of bubbles, and the flow rate tends to fluctuate.
[0005]
Since the city water circulates in the exhaust heat recovery pipe 12, pressure loss in the pipe may increase due to clogging such as dust and rust in the pipe. In such a case, even if the output of the circulation pump 11 is increased, the flow rate does not increase, and heat is not sufficiently recovered. Therefore, the temperature of the cooling water in the cooling pipe 8 rises, which hinders the power generation of the fuel cell 1. There is a problem that it causes.
Also, it is desired that abnormalities such as a failure of the circulation pump 11, clogging of the exhaust heat recovery pipe 12, leakage, defective exhaust heat recovery, etc. are constantly monitored, and that an abnormal situation can be dealt with promptly.
[0006]
Further, in order to avoid an increase in pressure loss due to clogging due to dirt or rust in the exhaust heat recovery pipe 12, etc., and to prevent a decrease in the flow rate of water in the exhaust heat recovery pipe 12, the output of the circulation pump 11 is more than a certain value. It is conceivable that the control is performed so that However, since the temperature of the water sent to the hot water storage tank 13 falls by controlling in this way, the temperature of the water of the upper layer part in the hot water storage tank 13 falls. Therefore, there is a problem that convenience is impaired such that hot water cannot be used unless all the water in the hot water storage tank 13 is boiled.
[0007]
In order to solve the above-described conventional problems, the present invention does not cause an abnormal temperature rise of the fuel cell due to pressure loss of the cooling pipe for recovering heat generated in the fuel cell and the exhaust heat recovery pipe for heat exchange, and the high temperature water. An object of the present invention is to provide a fuel cell system that can stably supply the fuel.
[0008]
[Means for Solving the Problems]
Fuel cell system includes: a fuel cell for generating electric power and heat using fuel gas and oxidant gas, and cooling pipes for circulating cooling water for recovering heat generated by the fuel cell, an external water heater A hot water storage tank for storing hot water to be supplied to the load, a heat exchanger for transferring the heat recovered by the cooling water to the water in the hot water storage tank, one end at the top of the hot water storage tank, and the other at the hot water storage tank An exhaust heat recovery pipe connected to the bottom part for circulating the water in the hot water storage tank to the heat exchanger, and a circulation pump provided in the exhaust heat recovery pipe for returning the water in the hot water storage tank to the hot water storage tank through the heat exchanger If, with the battery temperature detector for detecting the temperature of the temperature or before Kihiya却水of the fuel cell, and a controller for controlling the output of the circulation pump, wherein the control device is detected by the battery temperature detector Is When the temperature is lower than a second predetermined temperature lower than the first predetermined temperature at which the operation stop operation is performed due to the temperature increase of the fuel cell, the output of the circulation pump is controlled according to the power generation amount of the fuel cell. When the temperature detected by the battery temperature detector becomes equal to or higher than the second predetermined temperature, the output of the circulation pump is forcibly controlled to be equal to or higher than a predetermined value.
[0009]
The present invention also provides a fuel cell that generates electric power and heat using fuel gas and oxidant gas, a cooling pipe that circulates cooling water for recovering the heat generated in the fuel cell, and an external hot water supply load. A hot water storage tank for storing hot water, a heat exchanger for transferring the heat recovered by the cooling water to the water in the hot water storage tank, one end at the top of the hot water storage tank, and the other end at the bottom of the hot water storage tank, respectively An exhaust heat recovery pipe connected to circulate the water in the hot water storage tank to the heat exchanger; and a circulation pump provided in the exhaust heat recovery pipe for returning the water in the hot water storage tank to the hot water storage tank through the heat exchanger; A fuel cell system operating method comprising: a battery temperature detector that detects a temperature of the fuel cell or a temperature of the cooling water, wherein the temperature detected by the cell temperature detector is an increase in the temperature of the fuel cell. Therefore, when the temperature is lower than the second predetermined temperature lower than the first predetermined temperature at which the operation is stopped, the output of the circulation pump is controlled according to the power generation amount of the fuel cell, and is detected by the battery temperature detector. The output of the circulating pump is forcibly controlled to a predetermined value or higher when the temperature reaches the second predetermined temperature or higher.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0011]
Example 1
FIG. 1 is a configuration diagram of a fuel cell system according to Embodiment 1 of the present invention.
1, those having the same functions as those of the conventional fuel cell system shown in FIG. 5 are given the same reference numerals, and the details of those functions are the same as those in FIG. .
[0012]
Reference numeral 14 denotes a battery temperature detector such as a thermistor for detecting the temperature of the cooling water that recovers the heat generated from the fuel cell 1, and is installed on the outlet side of the cooling pipe 8 from the fuel cell 1. 15, when the temperature of the cooling water detected by the battery temperature detector 14 is less than the upper limit value of the operating temperature, the flow rate of water in the exhaust heat recovery pipe 12 becomes a predetermined flow rate according to the power generation amount of the fuel cell 1. The output of the circulation pump 11 is controlled as described above, and when this temperature becomes equal to or higher than the upper limit value of the operating temperature, the output of the circulation pump 11 is forcibly forced regardless of the power generation amount of the fuel cell 1 and the cooling water temperature is changed to the fuel cell 1 or the cooling pipe. 8 is a control device that controls to a value that does not reach a temperature at which deterioration of members such as the pump 9 and the battery temperature detector 14 arranged at 8 becomes severe.
[0013]
Next, the operation and action will be described.
During operation of the fuel cell system, the fuel processing device 2 steam-reforms a raw material such as natural gas, generates a gas mainly containing hydrogen, and supplies the gas to the fuel cell 1. Further, the oxidant gas is humidified by the oxidation side humidifier 7 by the air supply device 6 and supplied to the fuel cell 1. On the other hand, the heat generated by the power generation of the fuel cell 1 is recovered by the cooling water flowing in the cooling pipe 8. The cooling water is circulated by the pump 9, and the heat recovered in the cooling water moves to the water circulating in the exhaust heat recovery pipe 12 via the heat exchanger 10.
[0014]
When the temperature of the cooling water detected by the battery temperature detector 14 is less than the upper limit value of the operating temperature, the control device 15 sets the flow rate of water in the heat recovery pipe 12 to a predetermined flow rate according to the amount of power generated by the fuel cell 1. The output of the circulation pump 11 is controlled so that
In addition, when the temperature of the cooling water becomes equal to or higher than the upper limit value of the operating temperature, the control device 15 forces the output of the circulation pump to the pump 9 or the battery temperature detector in which the cooling water temperature is arranged in the fuel cell 1 or the cooling pipe 8. The temperature is controlled to a value that does not reach a temperature at which deterioration of the member such as 14 becomes severe.
[0015]
For example, if a normal operation is performed at 70 to 85 ° C. using a polymer electrolyte fuel cell, the output of the circulation pump 11 is forced when the operating temperature reaches 90 ° C. or higher. Increase the cooling water temperature to a value that does not reach around 100 ° C where the deterioration of the components such as the pump 9 and the battery temperature detector 14 arranged in the fuel cell 1 or the cooling pipe 8 becomes severe, and quickly normal operation Return to temperature.
[0016]
By adopting such a configuration, it is possible to prevent an increase in pressure loss due to generation of bubbles in the exhaust heat recovery pipe 12 and clogging of dust and the like, and a rise in temperature of the fuel cell 1 can be prevented. Moreover, since it is not necessary to perform an operation stop operation such as an emergency stop due to a temperature rise of the fuel cell 1, stable power generation can be continued for a long time.
[0017]
In the above embodiment, the battery temperature detector 14 is configured to detect the temperature of the cooling water from which heat has been recovered from the fuel cell 1, but may also be configured to detect the internal or surface temperature of the fuel cell 1 itself. Good.
[0018]
<< Reference Example 1 >>
The reference example 1 is different from the first embodiment in the function of the control device 15 in FIG.
That is, the control device 15 in Reference Example 1 has the following functions.
A change per unit time in the output of the circulation pump 11 is ΔW, and a change per unit time in the cooling water temperature detected by the battery temperature detector 14 is ΔT. The ratio ΔT / ΔW between the output change ΔW of the circulation pump 11 and the temperature change ΔT of the cooling water is within a certain range during the normal operation of the fuel cell 1. However, when pressure loss increases due to generation of bubbles in the exhaust heat recovery pipe 12 or clogging of dust, and the cooling water temperature rises, the ΔT / ΔW value exceeds the upper limit during normal operation. If the state where ΔT / ΔW is equal to or higher than the upper limit value during normal operation is continued for a predetermined period of time until the temperature of the cooling water reaches the upper limit value of the operating temperature after ΔT / ΔW exceeds the upper limit value, the circulation pump 11 is forcibly controlled so that the cooling water temperature does not reach a temperature at which deterioration of members such as the pump 9 and the battery temperature detector 14 disposed in the fuel cell 1 or the cooling pipe 8 becomes severe. In addition, the state where ΔT / ΔW is equal to or lower than the lower limit value during normal operation is a predetermined value such that the temperature of the cooling water reaches a temperature slightly higher than the lower limit value of the operating temperature after the ΔT / ΔW value becomes lower than the lower limit value. When the time continues, the output of the circulation pump 11 is forcibly controlled to a value that does not fall below the lower limit value of the operating temperature.
[0019]
Next, the operation and action will be described.
The control device 15 controls the output of the circulation pump 11 so that the flow rate of water in the exhaust heat recovery pipe 12 becomes a predetermined flow rate according to the power generation amount of the fuel cell 1, and the cooling detected by the battery temperature detector 14. Monitor water temperature. In some cases, the output of the circulation pump 11 continuously increases as the power generation amount increases, and the temperature of the cooling water detected by the battery temperature detector 14 increases continuously. At this time, when the state in which ΔT / ΔW is equal to or higher than the upper limit value during normal operation continues for a predetermined time after the ΔT / ΔW value exceeds the upper limit value, the temperature of the cooling water reaches the upper limit value of the operation temperature. The control device 15 forces the output of the circulation pump 11 so that the cooling water temperature does not reach a temperature at which deterioration of members such as the pump 9 and the battery temperature detector 14 arranged in the fuel cell 1 or the cooling pipe 8 becomes severe. Control.
[0020]
Moreover, while the output of the circulation pump 11 reduces continuously according to the reduction | decrease in electric power generation, the temperature of the water in the exhaust heat recovery piping 12 may fall continuously. At this time, the state where ΔT / ΔW is equal to or lower than the lower limit value during normal operation is such that the temperature of the cooling water is lowered to a temperature slightly higher than the lower limit value of the operating temperature after the ΔT / ΔW value becomes lower than the lower limit value. When the predetermined time continues, the control device 15 forcibly controls the output of the circulation pump 11 so that the temperature of the cooling water does not fall below the lower limit value of the operating temperature.
[0021]
By adopting such a configuration, not only the same effects as in the first embodiment can be obtained, but also when the temperature of the fuel cell 1 continuously decreases, the output of the circulation pump 11 is forcibly changed to the temperature of the cooling water. If the temperature of the fuel cell 1 does not change even if it is controlled to a value that does not fall below the lower limit value of the operating temperature, it is a failure of the exhaust heat recovery system in the power generator such as a failure of the circulation pump 11 or the battery temperature detector 14. It can be detected, and can respond quickly when an abnormality occurs.
[0022]
<< Reference Example 2 >>
FIG. 2 is a configuration diagram of the fuel cell system in this reference example.
2, components having the same functions as those of the fuel cell system shown in FIG. 1 are given the same reference numerals, and descriptions of these functions are omitted.
[0023]
Reference numeral 17 denotes an exhaust heat recovery temperature detector such as a thermistor for detecting the temperature of the water in the exhaust heat recovery pipe 12 from which the exhaust heat has been recovered by the heat exchanger 10, and from the heat exchanger 10 of the exhaust heat recovery pipe 12 It is installed on the exit side.
18, as in the control device 15 of the first embodiment, when the temperature of the cooling water detected by the battery temperature detector 14 is less than the upper limit value of the operating temperature, the exhaust heat recovery pipe according to the power generation amount of the fuel cell 1. The output of the circulation pump 11 is controlled so that the flow rate of the water in 12 becomes a predetermined flow rate. When this temperature exceeds the upper limit value of the operating temperature, the output of the circulation pump 11 is forcibly set regardless of the power generation amount of the fuel cell 1. Further, the control device has a function of controlling the cooling water temperature to a value that does not reach a temperature at which the deterioration of members such as the pump 9 and the battery temperature detector 14 disposed in the fuel cell 1 or the cooling pipe 8 becomes severe.
[0024]
Further, the control device 18 has a function of controlling the output of the circulation pump 11 so that the temperature of water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes substantially constant. That is, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes equal to or higher than the upper limit value of the set temperature related to the upper limit value of the operating temperature of the fuel cell 1, the temperature is decreased. The output of the circulation pump 11 is increased to increase the flow rate of water in the exhaust heat recovery pipe 12. Further, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 is equal to or lower than the lower limit value of the set temperature related to the lower limit value of the operating temperature of the fuel cell 1, the temperature is increased. The output of the circulation pump 11 is lowered, and the flow rate of water in the exhaust heat recovery pipe 12 is reduced. In this way, the temperature of the water in the exhaust heat recovery pipe 12 is maintained almost constant.
[0025]
Next, the operation and action will be described.
As in the first embodiment, the control device 18 is configured so that the temperature of the cooling water detected by the battery temperature detector 14 is less than the upper limit value of the operating temperature. The output of the circulation pump 11 is controlled so that the flow rate of the water becomes a predetermined flow rate, and when the temperature exceeds the upper limit value of the operating temperature, the output of the circulation pump 11 is forcibly cooled regardless of the power generation amount of the fuel cell 1. The water temperature is controlled to a value that does not reach a temperature at which deterioration of members such as the pump 9 and the battery temperature detector 14 disposed in the fuel cell 1 or the cooling pipe 8 becomes severe.
[0026]
When the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes equal to or higher than the upper limit value of the set temperature related to the upper limit value of the operating temperature of the fuel cell 1, the control device 18 In order to lower the temperature, the output of the circulation pump 11 is increased and the flow rate of water in the exhaust heat recovery pipe 12 is increased. Further, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 falls below the lower limit value of the set temperature related to the lower limit value of the operating temperature of the fuel cell 1, The output of the circulation pump 11 is lowered, and the flow rate of water in the exhaust heat recovery pipe 12 is reduced. In this way, the temperature of the water in the exhaust heat recovery pipe 12 is controlled to be substantially constant.
[0027]
In particular, when the amount of power generation is small, the flow rate of water in the exhaust heat recovery pipe 12 decreases, so the output of the circulation pump 11 is reduced to maintain the temperature of the water in the exhaust heat recovery pipe 12 at a predetermined temperature. At this time, pressure loss increases due to generation of bubbles in the exhaust heat recovery pipe 12 and clogging of dust. However, the control device 18 outputs the output of the circulation pump 11 when the battery temperature rises above the upper limit value of the operating temperature due to an increase in pressure loss in the exhaust heat recovery pipe 12 due to generation of bubbles or clogging of dust. The cooling water temperature is compulsorily controlled to a value that does not reach a temperature at which deterioration of members such as the pump 9 and the battery temperature detector 14 disposed in the fuel cell 1 or the cooling pipe 8 becomes severe . Also, since it is not necessary to the operation stop of the emergency stop or the like due to the temperature rise of the fuel cell can continue stable power generation over a long period of time.
[0028]
In addition, although the control apparatus of this reference example includes the function of the control apparatus of Example 1, you may comprise the function of the control apparatus of Reference example 1 instead.
[0029]
<< Reference Example 3 >>
FIG. 3 is a configuration diagram of the fuel cell system in the present reference example.
3, components having the same functions as those of the fuel cell system of Reference Example 2 shown in FIG. 2 are given the same reference numerals, and descriptions of those functions are omitted.
[0030]
A bypass pipe 19 branches from the exhaust heat recovery pipe 12 from the outlet side of the circulation pump 11 to the inlet side of the heat exchanger 10 and is connected to the hot water storage tank 13 through a valve 20 such as an electromagnetic valve.
A control device 21 has a function of controlling the output of the circulation pump 11 so that the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes substantially constant. That is, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes equal to or higher than the upper limit value of the set temperature related to the upper limit value of the operating temperature of the fuel cell 1, the temperature is decreased. The output of the circulation pump 11 is increased to increase the flow rate of water in the exhaust heat recovery pipe 12. Further, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 falls below the lower limit value of the set temperature related to the lower limit value of the operating temperature of the fuel cell 1, The output of the circulation pump 11 is lowered, and the flow rate of water in the exhaust heat recovery pipe 12 is reduced. In this way, the temperature of the water in the exhaust heat recovery pipe 12 is maintained almost constant.
[0031]
Further, when the power generation amount of the fuel cell decreases and the temperature of the cooling water detected by the battery temperature detector 14 falls below a temperature that is slightly higher than the lower limit value of the operating temperature, the control device 21 opens the valve 20 and bypasses it. It has a function of opening the pipe 19.
[0032]
Next, the operation and action will be described.
The control device 21 reduces the temperature when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 is equal to or higher than the upper limit value of the set temperature related to the upper limit value of the operating temperature of the fuel cell 1. Therefore, the output of the circulation pump 11 is increased, and the flow rate of water in the exhaust heat recovery pipe 12 is increased. Further, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 falls below the lower limit value of the set temperature related to the lower limit value of the operating temperature of the fuel cell 1, The output of the circulation pump 11 is lowered, and the flow rate of water in the exhaust heat recovery pipe 12 is reduced. In this way, the temperature of the water in the exhaust heat recovery pipe 12 is controlled to be substantially constant.
Further, when the amount of power generation decreases and the temperature of the cooling water detected by the battery temperature detector 14 falls below a temperature slightly higher than the lower limit value of the operating temperature, the valve 20 is opened and the bypass pipe 19 is opened.
[0033]
When the valve 20 is opened and the bypass pipe 19 is opened, a part of the water supplied by the circulation pump 11 returns to the hot water storage tank 13 via the bypass pipe 19, so that the water supplied to the heat exchanger 10. Decrease. Therefore, even when the power generation amount is reduced, the temperature of the water in the exhaust heat recovery pipe 12 that has recovered the heat by the heat exchanger 10 can be maintained at a high temperature.
[0034]
Therefore, hot water can be stably supplied to the hot water storage tank 13, and hot water can be used when the required amount has been heated without waiting for the entire amount of water in the hot water storage tank 13 to be heated.
Further, a control device that combines the function of the control device of the present reference example and the function of the control device of the first embodiment or the reference example 1 may be used.
In the above reference example, the control device is configured to monitor the temperature of the cooling water detected by the battery temperature detector as a method of monitoring the power generation amount, but may be configured to directly monitor the power generation amount of the fuel cell. Good.
[0035]
<< Reference Example 4 >>
FIG. 4 is a configuration diagram of the fuel cell system in this reference example.
4, components having the same functions as those of the fuel cell system of Reference Example 3 shown in FIG. 3 are given the same reference numerals, and descriptions of those functions are omitted.
[0036]
A valve 22 is provided in a bypass pipe 19 that branches from the exhaust heat recovery pipe 12 from the outlet side of the circulation pump 11 to the inlet side of the heat exchanger 10 and is connected to the hot water storage tank 13. The flow rate of water can be adjusted.
23 is a control device having a function of controlling the output of the circulation pump 11 so that the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes substantially constant. That is, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 becomes equal to or higher than the upper limit value of the set temperature related to the upper limit value of the operating temperature of the fuel cell 1, the temperature is decreased. The output of the circulation pump 11 is increased to increase the flow rate of water in the exhaust heat recovery pipe 12. Further, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 falls below the lower limit value of the set temperature related to the lower limit value of the operating temperature of the fuel cell 1, The output of the circulation pump 11 is lowered, and the flow rate of water in the exhaust heat recovery pipe 12 is reduced. In this way, the temperature of the water in the exhaust heat recovery pipe 12 is maintained almost constant.
[0037]
Further, when the power generation amount of the fuel cell 1 decreases and the temperature of the cooling water detected by the battery temperature detector 14 falls below a temperature slightly higher than the lower limit value of the operating temperature, the control device 23 detects the battery temperature detector 14. The valve 22 is controlled so that the flow rate of the water in the bypass pipe 19 increases as the temperature of the cooling water detected by the engine decreases.
[0038]
Next, the operation and action will be described.
The control device 23 reduces the temperature when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 is equal to or higher than the upper limit value of the set temperature related to the upper limit value of the operating temperature of the fuel cell 1. Therefore, the output of the circulation pump 11 is increased, and the flow rate of water in the exhaust heat recovery pipe 12 is increased. Further, when the temperature of the water in the exhaust heat recovery pipe 12 detected by the exhaust heat recovery temperature detector 17 falls below the lower limit value of the set temperature related to the lower limit value of the operating temperature of the fuel cell 1, The output of the circulation pump 11 is lowered, and the flow rate of water in the exhaust heat recovery pipe 12 is reduced. In this way, the temperature of the water in the exhaust heat recovery pipe 12 is controlled to be substantially constant.
[0039]
Further, when the power generation amount of the fuel cell 1 decreases and the temperature of the cooling water detected by the battery temperature detector 14 falls below a temperature slightly higher than the lower limit value of the operating temperature, the control device 23 detects the battery temperature detector 14. The valve 22 is controlled so that the flow rate of the water in the bypass pipe 19 increases as the temperature of the cooling water detected by the engine decreases.
At this time, part of the water supplied by the circulation pump 11 returns to the hot water storage tank 13 via the bypass pipe 19, so the flow rate of the water supplied to the heat exchanger 10 decreases. Therefore, even when the power generation amount is reduced, the temperature of the water in the exhaust heat recovery pipe 12 for which the heat has been recovered by the heat exchanger 10 can be maintained at a high temperature.
[0040]
Therefore, hot water can be stably supplied to the hot water storage tank 13, and hot water can be used when the required amount has been heated without waiting for the entire amount of water in the hot water storage tank 13 to be heated.
In addition, the pump 9 in FIGS. 1-4 is controlled so that it may operate | move at the time of electric power generation by the control apparatus 15, 18, 21, or 23, and is output constant during operation | movement.
[0041]
【The invention's effect】
As described above, according to the present invention, there is no abnormal temperature rise of the fuel cell due to pressure loss of the cooling pipe for recovering the heat generated in the fuel cell and the exhaust heat recovery pipe for heat exchange, and the high-temperature water is stabilized. The fuel cell system can be provided.
[Brief description of the drawings]
FIG. 1 is a block configuration diagram of a fuel cell system in Example 1 and Reference Example 1 of the present invention.
FIG. 2 is a block diagram of a fuel cell system in Reference Example 2 .
3 is a block diagram of a fuel cell system in Reference Example 3. FIG.
4 is a block diagram of a fuel cell system in Reference Example 4. FIG.
FIG. 5 is a block diagram of a conventional fuel cell system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Fuel processing apparatus 3 Reformer 4 Carbon monoxide converter 5 Fuel humidifier 6 Air supply apparatus 7 Oxidation side humidifier 8 Cooling pipe 9 Pump 10 Heat exchanger 11 Circulation pump 12 Waste heat recovery pipe 13 Hot water storage tank 14 Battery temperature detector 15, 18, 21, 23 Control device 17 Waste heat recovery temperature detector 19 Bypass piping 20, 22 Valve

Claims

A fuel cell that generates electric power and heat using fuel gas and an oxidant gas, a cooling pipe that circulates cooling water for recovering the heat generated in the fuel cell, and hot water for supply to an external hot water supply load are stored. A hot water storage tank, a heat exchanger for transferring heat recovered by the cooling water to the water in the hot water storage tank, one end connected to the upper part of the hot water storage tank, and the other end to the bottom part of the hot water storage tank, An exhaust heat recovery pipe that circulates the water in the heat exchanger to the heat exchanger; a circulation pump that is provided in the exhaust heat recovery pipe and returns the water in the hot water storage tank to the hot water storage tank through the heat exchanger; includes a battery temperature detector for detecting the temperature of Kihiya却水, and a controller for controlling the output of the circulation pump,
The controller is
When the temperature detected by the battery temperature detector is lower than a second predetermined temperature that is lower than a first predetermined temperature at which the operation stop operation is performed due to the temperature increase of the fuel cell, depending on the power generation amount of the fuel cell To control the output of the circulation pump,
When the temperature detected by the battery temperature detector becomes equal to or higher than the second predetermined temperature, the output of the circulation pump is forcibly controlled to be equal to or higher than a predetermined value.

The fuel cell system, wherein the second predetermined temperature is an upper limit value of an operating temperature of the fuel cell.

A fuel cell that generates electric power and heat using fuel gas and an oxidant gas, a cooling pipe that circulates cooling water for recovering the heat generated in the fuel cell, and hot water for supply to an external hot water supply load are stored. A hot water storage tank, a heat exchanger for transferring the heat recovered by the cooling water to the water in the hot water storage tank, one end connected to the upper part of the hot water storage tank, and the other end to the bottom of the hot water storage tank, An exhaust heat recovery pipe for circulating the water in the heat exchanger, a circulation pump provided in the exhaust heat recovery pipe for returning the water in the hot water storage tank to the hot water storage tank through the heat exchanger, the temperature of the fuel cell or the A battery temperature detector for detecting a temperature of the cooling water, and a method for operating the fuel cell system,
When the temperature detected by the battery temperature detector is lower than a second predetermined temperature that is lower than a first predetermined temperature at which the operation stop operation is performed due to the temperature increase of the fuel cell, depending on the power generation amount of the fuel cell To control the output of the circulation pump,
An operating method of a fuel cell system, wherein when the temperature detected by the battery temperature detector becomes equal to or higher than the second predetermined temperature, the output of the circulation pump is forcibly controlled to be equal to or higher than a predetermined value.

The method of operating a fuel cell system, wherein the second predetermined temperature is an upper limit value of the operating temperature of the fuel cell.