JP3871792B2

JP3871792B2 - Fuel cell device

Info

Publication number: JP3871792B2
Application number: JP35807297A
Authority: JP
Inventors: 秀人久保; 良雄木村; 信雄藤田; 博史青木; 宏之三井
Original assignee: Toyota Industries Corp; Toyota Motor Corp; Toyota Central R&D Labs Inc
Current assignee: Toyota Industries Corp; Toyota Motor Corp; Toyota Central R&D Labs Inc
Priority date: 1997-12-25
Filing date: 1997-12-25
Publication date: 2007-01-24
Anticipated expiration: 2017-12-25
Also published as: JPH11185792A

Description

【０００１】
【発明の属する技術分野】
本発明はリフォ−マ、水素吸蔵合金内蔵タンクおよび燃料電池のセットを含む燃料電池装置に関する。
【０００２】
【従来の技術】
実開平６−８２７５６号公報は、炭化水素またはメタノ−ルから水素含有ガス（以下、反応ガスともいう）を発生する改質器（リフォ−マ）、燃料電池（セル）を用いる燃料電池装置において、リフォ−マと燃料電池との間に水素吸蔵合金内蔵タンク（ＭＨタンク）を付加し、燃料電池の発生電力を用いる電気回路の状態に基づいてＭＨタンクの授受熱量を制御し、これによりリフォ−マの水素産生レ−トと燃料電池の水素消費レ−トとのアンバランスを一時的（ＭＨタンクの容量分だけ）補償することを提案している。
【０００３】
【発明が解決しようとする課題】
しかしながら、上記した従来のＭＨタンク付き燃料電池装置では、以下の問題点があった。
第一に、ＭＨタンクの水素の吸蔵、放出は、リフォ−マの水素産生レ−トと燃料電池の水素消費レ−トとの差に無関係に、燃料電池の電気回路の状況に応じて行われるので、たとえばリフォ−マの水素産生レ−トの状況にかかわらずＭＨタンクの水素の吸蔵、放出制御を行うので燃料電池への水素ガス供給が不適切となる可能性が生じた。たとえば、リフォ−マの水素産生レ−トが最大状態となっている場合にＭＨタンクから水素ガスを放出したとしても燃料電池の最大水素消費能力をオ−バ−してしまい無駄が生じる。
【０００４】
また、なんらかの原因でリフォ−マの水素産生レ−トが変動してしまった場合でも、それが燃料電池の電気回路の状況に反映するには時間がかかるので燃料電池の発電に過不足が生じた。
また、上記電気回路における状態変化はその電気負荷、たとえばモータなどのオンオフなどにより頻繁かつ急激に変化するが、ＭＨタンクの水素ガスの吸蔵，放出の切り替えは実際はバルブなどで温熱供給と冷熱供給とを切り替えたとしても、ＭＨタンクの水素吸蔵合金の温度変化がそれほど容易に変化するものではなく、その結果、電気回路の電力状況変化へのＭＨタンクの水素吸蔵、放出動作の追従遅れにより、電気負荷が増大したにもかかわらずＭＨタンクは水素吸蔵状態となっていたり、電気負荷が減少したにもかかわらずＭＨタンクは水素放出状態となっていたりする場合が生じる。
【０００５】
更に、電気負荷の変化に応じてＭＨタンクの水素吸蔵、放出動作を頻繁に切り替えるということは、現実には少し暖まりかけた水素吸蔵合金をすぐに冷やしたり、やっと冷えかけた水素吸蔵合金をまた暖めることになったりすることになって、熱経済上、無駄が多かった。すなわち、原理的にＭＨタンクは水素吸蔵、放出動作を高速に切り替えたり、変化させたりしにくいので、このような緩慢なＭＨタンクの水素の吸蔵、放出の切り替え動作を電気負荷の運転状況により高速かつ頻繁に変化する電気回路の状況変化で制御するのは熱経済の観点などから問題があった。
【０００６】
次に、上述した従来のＭＨタンク付き燃料電池装置では、ＭＨタンクの水素吸蔵、放出動作は、単にＭＨタンクの授受熱量を制御する（切り替える）のみで行うので、動作が遅かった。
更に具体的に説明すれば、通常のバランス（水素消費レ−ト＝水素産生レ−ト）状態においてＭＨタンクの水素分圧は平衡圧力点にある。水素不足が生じ、ＭＨタンクの水素分圧が低下すると、この低下した水素分圧の平衡圧力点に一致するまで水素吸蔵合金から水素が放出されるが、この時、水素吸蔵合金が自己冷却するので、その水素放出能力は急速に低下してしまう。このため外部熱源から水素吸蔵合金の加熱とその昇温が行われるが、これは、熱媒流体の加熱とその昇温を経た後でなされる。
【０００７】
しかし、熱媒流体およびその配管、ＭＨタンクの熱容量および熱損失が無視できない大きさであるので、水素吸蔵合金を最終的に十分に高温として、その水素吸蔵量が大幅に減少するレベルまで上記水素分圧の平衡圧力点を低下させるには長い時間が必要となる。これは水素過剰の場合にも同じである。
特に、水素不足状態から水素過剰状態に一気に変化する場合には、外部熱交換器、熱媒流体およびその配管、並びにＭＨタンクを高温状態から低温状態へシフトする必要があり、上記した平衡圧力点からのシフトよりも更に長い時間が必要となる。
【０００８】
すなわち、熱媒流体の温度変化のみによりＭＨタンクの水素分圧の平衡圧力点をシフトさせる上記従来のＭＨタンク付き燃料電池装置は、水素補償のレスポンスが遅いという問題があった。
本発明は、上記問題点に鑑みなされたものであり、ＭＨタンクの加熱冷却における熱経済の無駄が少なく、更にＭＨタンクの水素吸蔵、放出動作のレスポンスも向上可能なＭＨタンク付きの燃料電池装置を提供することをその解決すべき課題としている。
【０００９】
【課題を解決するための手段】
請求項１記載の燃料電池装置では、リフォ−マと燃料電池との間に配設された水素吸蔵合金内蔵タンク（ＭＨタンク）は、圧縮手段及び調圧手段の採用により、少なくとも燃料電池の燃料極の作動圧より格段に高圧（リフォ−マの水素産生レ−トと燃料電池の水素消費レ−トとが一致する均衡状態で少なくとも１ｋｇ／平方ｃｍＧ以上）で使用され、更に、ＭＨタンクの水素吸蔵、放出動作を制御するための熱量授受はリフォーマの水素産生レ−トと燃料電池の水素消費レ−トとの差に関連する状態量に基づいてなされる。
【００１０】
なおここでいう圧縮手段とは、請求項３で記載するようにリフォ−マへ原燃料を供給するポンプ、又は、請求項４で記載するようにリフォ−マから産生される水素含有ガスを圧縮する圧縮機を意味する。
このようにすれば以下の作用効果を奏することができる。
まず、本構成では、圧縮手段及び調圧手段の採用により燃料電池の作動圧力より格段に高圧で用いられるので、ＭＨタンクの水素吸蔵、放出動作のレスポンス遅れを改善することができる。
【００１１】
更に詳しく説明すれば、いま燃料電池の水素消費レ−トが急に増大してその作動圧力が急低下したとする。すると、調圧手段が開いてＭＨタンクから燃料電池への水素含有ガス放出レ−トが増大し、ＭＨタンクの圧力が低下する。すると、この圧力低下に応じて、ＭＨタンクの水素吸蔵合金は水素ガスを放出する。この時点ではまだＭＨタンクの水素吸蔵合金と外部熱源との間の熱量授受レ−トの変更は行われないので、この時に水素ガス放出に必要な潜熱は、主に水素吸蔵合金、熱媒流体などの熱容量すなわちその温度低下（顕熱）で賄われる。すなわち、水素吸蔵合金はその熱容量が許す温度低下が上記圧力低下とバランスするまで水素ガスを放出することができ、レスポンスよく燃料電池の水素消費レ−ト増加に対応することができる。もちろん、この圧力低下の限界はＭＨタンク圧力が燃料電池の作動圧力にほぼ一致する場合である。上述したレスポンス向上効果は同様に燃料電池の水素消費レ−トが急に減少してその作動圧力が急増した場合にも生じることは当然である。
【００１２】
次に、本構成では、水素消費レ−トと水素産生レ−トとの差に関するデ−タに応じてＭＨタンクの授受熱量を変化させるので、言い換えれば、実際のリフォ−マ及び燃料電池の両方の運転状況の差を補償するようにＭＨタンクを運転するので、ＭＨタンクの水素吸蔵、放出動作と、リフォ−マ及び燃料電池の両方の運転状況の実際の差との間のミスマッチングが生じないという効果を奏する。
【００１３】
すなわち、比較的緩慢に変化するＭＨタンクの水素吸蔵、放出動作は、電力変化よりも緩慢に変化するリフォ−マ及び燃料電池の両方の運転状況の実際の差に応じて変化するのでミスマッチングが生じにくく、かつリフォ−マの水素産生レ−トがなんらかの不具合の発生などの理由で変化してもそれにレスポンスよく対応するので従来の単に電力変化だけでＭＨタンクの水素吸蔵、放出動作を変更する場合に比較して一層ミスマッチングを減らせ、熱経済の無駄や燃料電池における水素ガスの余剰が生じにくく、効率がよい。
【００１４】
請求項２記載の構成によれば、請求項１記載の燃料電池装置において更に、水素吸蔵合金内蔵タンクの圧力に基づいて上記制御を実行するので、制御を簡素な構成で確実に実施することができる。
請求項３記載の構成によれば、請求項１又は２記載の燃料電池装置において、圧縮手段をリフォーマへ原燃料を供給する液ポンプとする。このようにすれば、圧縮手段を簡単に構成でき、圧縮に必要な動力を減らすことができる。
【００１５】
請求項４記載の構成によれば請求項１又は２記載の燃料電池装置において更に、圧縮手段をリフォ−マとＭＨタンクとの間の圧縮機とする。このようにすればＭＨタンクを燃料電池より十分に高圧下で使用するにもかかわらず、リフォ−マを低圧運転できるので、リフォ−マの耐圧低下によりその軽量化を図ることができる。
【００１６】
請求項５記載の構成によれば請求項３又は４記載の燃料電池装置において更に、水素吸蔵合金内蔵タンクの圧力が所定圧より高い場合に圧縮手段を減速し、低い場合に加速する。
このようにすれば、燃料電池の水素消費レ−トの変化に応じて燃料電池への水素供給レ−トを一時的にでも高速追従させることができる。
【００１７】
請求項６記載の構成によれば、請求項２乃至５のいずれか記載の燃料電池装置において更に、水素吸蔵合金内蔵タンクの圧力が所定圧より高い場合にリフォ−マの水素産生レ−トを低減させ、低い場合に増大させる。
このようにすれば、緩慢ではあるが、水素産生レ−トと水素消費レ−トとの差を低減して効率を向上することができる。
【００１８】
請求項７記載の構成によれば請求項１乃至６のいずれか記載の燃料電池装置において更に、リフォーマで生成された水素含有ガスを直接燃料電池へ供給するバイパス経路を設け、特定の条件、たとえば水素産生レ−トと水素消費レ−トとが一致する場合にバイパス回路を通じてリフォ−マからの水素含有ガスを供給する。このようにすればＭＨタンクを上記一致状態で切り離すことができ、それによる熱ロスなどを防止することができ、かつ、ＭＨタンクを好ましい圧力状態に制御（たとえば、燃料電池の水素消費レ−トが小さい場合にはＭＨタンクの水素吸蔵量を大きい状態としたり、燃料電池の水素消費レ−トが大きい場合にはＭＨタンクの水素吸蔵量を小さくしたりする制御）することができる。
【００１９】
【発明の実施の形態】
リフォ−マの原料としては、水素含有ガスを発生可能なものであればよく、たとえばメタノ−ルが好適である。リフォ−マの水素産生レ−トを変更するには、その燃焼器の発生熱量を制御させて実施されるが、この時、リフォ−マへの原料（たとえばメタノ−ルや水）の供給圧も制御することもできる。
【００２０】
調圧手段としては、ノズルなどの単純な機構の他、出力圧力を一定に制御するレギュレ−タなどを用いることができる。
燃料電池には、固体高分子電解質型燃料電池が好適である。燃料電池のカソ−ドには空気を過剰に供給することが経済上、一般的であり、その圧縮動力の低減のために、燃料電池の運転圧力は比較的低いレベルに設定されるのが好ましい。
【００２１】
【実施例１】
車両に走行動力を供給するための本発明の燃料電池の一実施例を、その配置図である図１を参照して説明する。
（構成の説明）
１はリフォ−マ（改質器）であって、メタノ−ルタンク２に貯蔵されているメタノ−ルがポンプ３で加圧されて供給され、同様に水タンク４に貯蔵されている水がポンプ５で加圧されて供給される。ポンプ３、５の流量は、コントロ−ラ６により算出、決定される水素産生レ−トに応じてその回転数の変化により制御され、両ポンプ３、５の最大吐出圧は５ｋｇ／平方ｃｍＧ以上、好ましくは５．５ｋｇ／平方ｃｍＧ程度に設定されている。リフォ−マ１は燃焼器１１を内蔵し、この燃焼器１１で発生する熱により、原料であるメタノ−ルおよび水を気化させ、水素を主体とする水素含有ガスに改質する。産生された水素含有ガスは、リフォ−マ１の転化器１２にてＣＯ濃度を低減された後、ＭＨタンク（水素吸蔵合金内蔵タンク）７に送られる。
【００２２】
ＭＨタンク７は、熱交換器および水素吸蔵合金（図示せず）が収容された耐圧容器からなり、内部に水素含有ガスの流通経路を有する。ＭＨタンク７に流入した水素含有ガスは、水素吸蔵合金と水素を授受しながらレギュレ−タ８を通じて所定の基準圧力（ここでは１ｋｇ／平方ｃｍＧ）に調圧されて燃料電池９の燃料極に流入する。
【００２３】
燃料電池９は、燃料極に流入する水素含有ガスと、図示しないブロワにより空気極に流入する空気との反応により水を産生して発電するとともに水素ガスが残留する排ガスを排出する。また、燃料電池９は熱を発生するので、その冷却のために水が循環される。この実施例では、ＭＨタンク７の水素放出時には、後述する循環ポンプ１６の運転により燃料電池９とＭＨタンク７との間での温水を循環させ、燃料電池９の発生熱をＭＨタンク７に与えている。また、ＭＨタンク７の水素放出時以外では、図示しない循環ポンプの運転により燃料電池９の発生熱は外部のラジエ−タに排出される。また、燃料電池９の排ガスは図示しないバルブを通じてリフォ−マ１の燃焼器１１に送られてメタノ−ルとともに燃焼される。燃料電池９で発生した電力は図示しない電気回路を通じて負荷に給電される。なお、燃焼器１１の発生熱量はポンプ３、５によりリフォ−マ１に供給される原燃料を処理するのに必要十分であるように調節される。
【００２４】
１５はファン付きの外部熱交換器（ラジエ−タ）であって、この外部熱交換器１５で冷却された冷水は切り替えバルブ１７、循環ポンプ１６、熱交換器７１、外部熱交換器１５と循環して水素吸蔵合金を冷却する。また、水素吸蔵合金の加熱時には、上述したように循環ポンプ１６から送出された水は、熱交換器７１、燃料電池９、切り替えバルブ１８と循環して水素吸蔵合金を加熱する。
【００２５】
２０はＭＨタンク７の圧力を検出する圧力センサであり、この実施例では、このＭＨタンク７の圧力に基づいて各種制御を実行する。なお、リフォ−マ１の水素産生レ−トと燃料電池９の水素消費レ−トとの差に応じた状態量としては、ＭＨタンク７の圧力の他にＭＨタンク７を循環する水の温度などでもよい。
（基本動作の説明）
以下、この燃料電池装置の基本動作を説明する。
【００２６】
ポンプ３、５を駆動し、レギュレ−タ８の調圧により燃料電池９の内圧が１ｋｇ／平方ｃｍＧとなるように調整し、燃料電池９から排出される排ガスはリフォ−マ１の燃焼器１１でメタノ−ルとともに燃やされ、リフォ−マ１は改質反応により水素含有ガスを産生する。リフォ−マ１が立ち上がるまでのリフォ−マ起動初期において、リフォ−マ１の水素産生レ−トの不足を補償するためにＭＨタンク７になんらかの方法で発生させた温水を送って水素ガスを放出させることができ、燃料電池９の運転の停止後のリフォ−マ１の運転終了に際してリフォ−マ１から産生される水素含有ガス中の水素ガスをＭＨタンク７に吸蔵するためにＭＨタンク７をラジエ−タ１５で冷却することができる。
（制御動作の説明）
次に、リフォ−マ１、ＭＨタンク７及び燃料電池９の能力制御について説明する。これらの能力制御を無段階制御することは当然可能であるが、この実施例では説明及び制御動作を簡単とするために多段階制御を行うものとして説明する。
【００２７】
（リフォ−マ１の制御）
リフォ−マ１の水素産生レ−トは、制御を簡単とするために、相対数値で表示して、最大（１００％運転＝１）、中間（５０％運転＝０．５）、停止（０）の３段階に制御するものとし、この制御はポンプ３、５の回転数の調節すなわちリフォ−マ１への原燃料の供給量を上記３段階に調節することにより行い、それに応じてリフォ−マ１の燃焼器１１の発生熱量もメタノ−ル供給量の調節により上記３段階に変更する。ただ、この実施例では、ＭＨタンク７の圧力を高圧に維持するために、ポンプ３、５の吐出圧は少なくとも燃料電池９への水素含有ガスの送出圧力が１ｋｇ／平方ｃｍＧ以上、この実施例ではＭＨタンクの圧力が最大限５．５ｋｇ／平方ｃｍＧに達し得るように設定する。
【００２８】
（ＭＨタンク７の制御）
ＭＨタンク７の水素吸蔵、放出レ−トはＭＨタンクの授受熱量により調節できるので、この実施例では、循環ポンプ１６の回転数を全負荷運転、部分負荷運転、停止の三段階に変更して１００％吸蔵、５０％吸蔵、停止、５０％放出、１００％放出の５段階に調節するものとする。
【００２９】
結局、ＭＨタンク７の１００％吸蔵又は１００％放出における水素授受量がリフォ−マ１の最大に等しいと簡単のために仮定すると、リフォ−マ１及びＭＨタンク７の動作の組み合わせにより、ＭＨタンク７から燃料電池９へ供給される水素供給レ−トは相対値で表示すれば、２、１．５、１、０．５、０の５段階に調節できることがわかる。
【００３０】
（燃料電池９の制御）
燃料電池９の発電能力（発電可能な電力）は、燃料電池９の燃料極の平均水素分圧と、それに対応して調節される燃料電池９の空気極の平均酸素分圧とにより決定され、これら平均分圧はこれらの極に供給される水素及び酸素の供給レ−トと、これらの極内における水素及び酸素の減少レ−トとに関連し、前者はＭＨタンク７から燃料電池９への水素含有ガスの流入流量に関連し、後者は燃料電池９の実際の発電量（水生成量）に関連する。したがって、燃料電池９の発電能力の制御としては、発電状況に応じて燃料電池９への水素含有ガス及び空気の流入流量を能動的に調節する場合（能動モ−ド）と、電気負荷の消費電力すなわち燃料電池９の実際の発電量に応じて燃料電池９内の水素分圧及び酸素分圧が変化することにより燃料電池９へ流入する水素含有ガス及び空気の流入流量が受動的に調節される場合（受動モ−ド）との２つが存在する。更に具体的に説明する。
【００３１】
まず能動モ−ドついて更に詳しく説明する。
燃料電池９の実際の発電量すなわち電気負荷の電力消費が増大傾向となって燃料電池９への現在の水素及び酸素の供給レ−トにより規定される発電能力を上回る可能性が生じる場合には燃料電池９への水素及び酸素の供給レ−トを両方とも無段階又は段階的に増大させて燃料電池９の発電能力を増大させ、逆の場合には、燃料電池９への水素及び酸素の供給レ−トを両方とも無段階又は段階的に減少させて燃料電池９の発電能力を減少させる。この燃料電池９への水素及び酸素の供給レ−トの能動的な調節は、燃料電池９からリフォ−マ１の燃焼器１１へ排出する排ガスの流量を制御する弁を開くことにより行う。たとえば、燃料電池９の発電能力の増大時には、このバルブを開くと排ガス流量の増大により燃料電池９の燃料極の圧力が低下してレギュレ−タ８の出力圧が低下傾向となり、これを補償するためにレギュレ−タ８が開いて水素含有ガス流量を増大させて燃料電池９の燃料極の圧力が基準圧に保持される。同様に、燃料電池９の空気極に空気を送る不図示のブロワの空気流量も上記水素含有ガス流量の増大に応じて増大される。なお、ブロワの空気流量はあらかじめ大きく設定しておいて制御を簡素化してもよい。燃料電池９の発電能力の減少時には上記と逆の動作を行うが、その説明は省略する。
【００３２】
次に受動モ−ドについて更に詳しく説明する。
燃料電池９の実際の発電量が増大すると、燃料電池９内の平均水素分圧及び平均酸素分圧が低下してその分だけ燃料電池９の圧力が低下するので、その分だけレギュレ−タ８の補償作用によりＭＨタンク７から燃料電池９への水素含有ガスの供給レ−トが増加する。なお、あらかじめ空気供給レ−トを多少過剰に設定しておけば、空気側の空気供給レ−トが水素含有ガスの供給レ−トと同じ割合で増加させなくてもよいので制御が簡単または不要となる。燃料電池９の発電量の減少時には上記と逆の動作を行うが、その説明は省略する。
【００３３】
なお、上記能動制御と受動制御とを一緒に行ってもよいが、場合によっては受動制御のみを行っても良い。燃料電池９の電気負荷は上記リフォ−マ１の水素産生レ−トの段階調節に合わせて１（１００％運転）、０．５（５０％運転）、停止の三段階に変化する負荷とすることが特に好ましいが、その他の任意に変化する電気負荷を用いることもできる。
【００３４】
また、この実施例のシステムに用いた場合に燃料電池９の最大水素消費レ−トは、リフォ−マ１の最大水素産生レ−トとＭＨタンク７の最大水素放出レ−トの合計に等しく、この実施例ではリフォ−マ１の最大水素産生レ−トの２倍に設定されている。これにより燃料電池９は本システムの運転条件下において最大でリフォ−マ１の水素産生レ−トに相当する発電能力の２倍の発電能力をもつように設計されている。
【００３５】
次に、マイコン内蔵のコントロ−ラ６によるリフォ−マ１及びＭＨタンク７の制御例について図２のフロ−チャ−トを参照して以下に説明する。
まず、予めリフォ−マ１及び燃料電池９を所定モ−ドで設定しておく。ただし、この初期時点では、燃料電池９の水素消費レ−トはリフォ−マ１の水素産生レ−トに一致するように設定しておくことが好ましい。
【００３６】
次に、圧力センサ２０からＭＨタンク７の圧力Ｐｍｈを検出する（Ｓ１００）。上述したように、ＭＨタンク７の圧力Ｐｍｈは上述した燃料電池９の能動的又は受動的な水素消費レ−トの変化により生じる。次に、Ｓ１０１に進み、検出した圧力Ｐｍｈに基づいてＭＨタンク７の制御を行う。
更に詳しく説明すると、圧力Ｐｍｈが３．０ｋｇ／平方ｃｍＧ未満の場合は、Ｓ１０２に進んでポンプ１６を能力１００％で駆動し、バルブ１７を閉じ、バルブ１８を開き、温熱を１００％供給してＭＨタンク７から１００％能力で水素を発生する。
【００３７】
圧力Ｐｍｈが３．０〜３．５ｋｇ／平方ｃｍＧの場合は、Ｓ１０３に進んでポンプ１６を能力５０％で駆動し、バルブ１７を閉じ、バルブ１８を開き、温熱を５０％供給してＭＨタンク７から５０％能力で水素を発生する。
圧力Ｐｍｈが４．５〜５．０ｋｇ／平方ｃｍＧの場合は、Ｓ１０４に進んでポンプ１６を能力５０％で駆動し、バルブ１７を開き、バルブ１８を閉じ、冷却水を５０％供給してＭＨタンク７で５０％能力で水素を吸収する。
【００３８】
圧力Ｐｍｈが５．０ｋｇ／平方ｃｍＧ以上の場合は、Ｓ１０５に進んでポンプ１６を能力１００％で駆動し、バルブ１７を開き、バルブ１８を閉じ、冷却水を１００％供給してＭＨタンク７により１００％能力で水素を吸収する。
Ｓ１０１にて、圧力Ｐｍｈが３．５〜４．５ｋｇ／平方ｃｍＧの範囲にある場合はリフォ−マ１の水素産生レ−トと燃料電池９の水素消費レ−トとがマッチングしているものとしてＳ１００へリタ−ンする。
【００３９】
次に、Ｓ１０２、Ｓ１０３では、リフォ−マ１の水素産生レ−トが燃料電池９の水素消費レ−トより小さいわけであるので、現在のリフォ−マ１の水素産生レ−トが５０％レ−トかどうかを調べ（Ｓ１０６）、そうであればその水素産生レ−トを１００％に変更して（Ｓ１０７）、Ｓ１００へリタ−ンする。Ｓ１０６にて現在のリフォ−マ１の水素産生レ−トが５０％でなければ、更に現在のリフォ−マ１の水素産生レ−トが０％（停止）かどうかを調べ（Ｓ１０８）、０％であれば５０％に増大して（Ｓ１０９）、０％であればただちに、Ｓ１００へリタ−ンする。
【００４０】
次に、Ｓ１０４、Ｓ１０５では、リフォ−マ１の水素産生レ−トが燃料電池９の水素消費レ−トより大きいわけであるので、現在のリフォ−マ１の水素産生レ−トが１００％レ−トかどうかを調べ（Ｓ１１０）、そうであればその水素産生レ−トを５０％に変更して（Ｓ１１１）、Ｓ１００へリタ−ンする。Ｓ１１０にて現在のリフォ−マ１の水素産生レ−トが１００％でなければ、更に現在のリフォ−マ１の水素産生レ−トが５０％かどうかを調べ（Ｓ１１２）、５０％であれば０％に減らして（Ｓ１１３）、０％であればただちに、Ｓ１００へリタ−ンする。
【００４１】
なお、上記したリフォ−マ１の水素産生レ−トの変更指令から実際のその変更には時間がかかるので、Ｓ１００からＳ１０５に至る制御を実際には多数回繰り返し、Ｓ１０６からＳ１０９に至るリフォ−マ１の水素産生レ−トの増大制御、又は、Ｓ１１０からＳ１１３に至るリフォ−マ１の水素産生レ−トの減少制御は所定のより長い時間経過した場合に初めて一回だけ実行することが好ましい。
【００４２】
【実施例２】
実施例１の変形態様である実施例２の燃料電池装置を図３を参照して説明する。
この燃料電池装置は、図１の燃料電池装置において、リフォ−マ１の出口と燃料電池９の入口との間をバイパスするバイパス経路３０を設け、このバイパス経路にレギュレ−タ３１を設け、更にリフォ−マ１とＭＨタンク７との間に逆止弁３２を設け、更にリフォ−マ１の出口に圧力センサ３３を設けたものである。
【００４３】
この実施例では、リフォ−マ１の水素産生レ−トと燃料電池９の水素消費レ−トとが一致する運転状況を検出し、一致する場合にレギュレ−タ３１を開いてリフォ−マ１の水素含有ガスをＭＨタンク７を経由することなく燃料電池９に供給する。
このようにすれば、無用な圧力損失を減らすことができ、また、ＭＨタンク７の水素吸蔵状態を最適レベルに維持することが容易となる。なお、レギュレ−タ３１によりバイパスを開始すると、逆止弁３２の存在のために圧力センサ２０が水素産生レ−トと水素消費レ−トとの差に追従しなくなる可能性があるので、図２の制御は圧力センサ３３に基づいて行うことができる。または、この実施例では、圧力センサ２０は非常検出用とし、図２の制御は常に圧力センサ３３で行ってもよい。
【００４４】
【実施例３】
実施例１の変形態様である実施例３の燃料電池装置を図４を参照して説明する。
この燃料電池装置は、図１の燃料電池装置において、リフォ−マ１とＭＨタンク７との間に圧縮機３４を設けたものである。圧縮機３４は燃料電池９へ水素を供給する場合にはＭＨタンク７の圧力を増大させるために運転される。
【００４５】
このようにすれば、リフォ−マ１を実施例１よりも格段に低圧で作動させることができるので、その耐圧低下により小型軽量化を図ることができる。
なお、図５は実施例２及び３を組み合わせたものであって、両実施例の作用効果を奏することができる。
【図面の簡単な説明】
【図１】この発明の実施例１の燃料電池装置のブロック図である。
【図２】図１の燃料電池装置のリフォ−マ１及びＭＨタンク７の制御を示すフロ−チャ−トである。
【図３】この発明の実施例２の燃料電池装置のブロック図である。
【図４】この発明の実施例３の燃料電池装置のブロック図である。
【図５】この発明の実施例４の燃料電池装置のブロック図である。
【符号の説明】
１はリフォ−マ、３はポンプ（圧縮手段）、５はポンプ（圧縮手段）、６はコントロ−ラ（制御手段）、７は水素吸蔵合金内蔵タンク（ＭＨタンク）、８はレギュレ−タ（調圧手段）、９は燃料電池、２０は圧力センサ（検出手段）。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel cell device including a reformer, a hydrogen storage alloy built-in tank, and a set of fuel cells.
[0002]
[Prior art]
Japanese Utility Model Publication No. 6-82756 discloses a fuel cell apparatus using a reformer (reformer) that generates a hydrogen-containing gas (hereinafter also referred to as a reaction gas) from a hydrocarbon or methanol, and a fuel cell (cell). A hydrogen storage alloy built-in tank (MH tank) is added between the reformer and the fuel cell, and the heat transfer amount of the MH tank is controlled based on the state of the electric circuit using the electric power generated by the fuel cell. -It is proposed to compensate temporarily (by the capacity of the MH tank) for an imbalance between the hydrogen production rate of the fuel cell and the hydrogen consumption rate of the fuel cell.
[0003]
[Problems to be solved by the invention]
However, the above-described conventional fuel cell device with an MH tank has the following problems.
First, storage and release of hydrogen in the MH tank is performed according to the state of the electric circuit of the fuel cell, regardless of the difference between the hydrogen production rate of the reformer and the hydrogen consumption rate of the fuel cell. Therefore, for example, hydrogen storage and release control of the MH tank is performed regardless of the status of the hydrogen production rate of the reformer, so that there is a possibility that the supply of hydrogen gas to the fuel cell becomes inappropriate. For example, even when hydrogen gas is released from the MH tank when the hydrogen production rate of the reformer is at its maximum, the maximum hydrogen consumption capacity of the fuel cell is exceeded, resulting in waste.
[0004]
Also, even if the reformer's hydrogen production rate fluctuates for some reason, it takes time to reflect it in the state of the electric circuit of the fuel cell. It was.
The state change in the electric circuit changes frequently and suddenly depending on the electric load, for example, on / off of the motor, etc., but the switching of hydrogen gas storage / release in the MH tank is actually performed by a valve or the like between hot and cold supply. Even if the MH tank is switched, the temperature change of the hydrogen storage alloy in the MH tank does not change so easily. There are cases where the MH tank is in a hydrogen occlusion state despite an increase in load, or the MH tank is in a hydrogen release state even though the electrical load is reduced.
[0005]
Furthermore, the frequent switching of the hydrogen storage and release operations of the MH tank in response to changes in the electrical load means that the hydrogen storage alloy that has started to warm up is cooled immediately or the hydrogen storage alloy that has finally started to cool down again. There was a lot of waste in terms of heat economy because it was supposed to warm up. That is, in principle, the MH tank does not easily switch or change the hydrogen storage / release operation at a high speed. Therefore, the slow MH tank storage / release switching operation is performed at a higher speed depending on the operating condition of the electric load. In addition, there is a problem from the viewpoint of thermal economy, etc., that the control is performed by changing the state of the electric circuit that changes frequently.
[0006]
Next, in the conventional fuel cell device with an MH tank described above, the hydrogen storage / release operation of the MH tank is performed only by controlling (switching) the heat transfer amount of the MH tank, and thus the operation is slow.
More specifically, in the normal balance state (hydrogen consumption rate = hydrogen production rate), the hydrogen partial pressure of the MH tank is at the equilibrium pressure point. When hydrogen shortage occurs and the hydrogen partial pressure in the MH tank decreases, hydrogen is released from the hydrogen storage alloy until it reaches the equilibrium pressure point of the reduced hydrogen partial pressure. At this time, the hydrogen storage alloy self-cools. As a result, the hydrogen releasing capacity is rapidly reduced. For this reason, the hydrogen storage alloy is heated and its temperature is raised from an external heat source. This is done after the heating of the heat transfer fluid and its temperature rise.
[0007]
However, since the heat capacity and heat loss of the heat transfer fluid and its piping and MH tank are not negligible, the hydrogen storage alloy is finally brought to a sufficiently high temperature, and the hydrogen storage capacity is reduced to a level at which the hydrogen storage capacity is greatly reduced. It takes a long time to lower the equilibrium pressure point of the partial pressure. The same is true for hydrogen excess.
In particular, when changing from a hydrogen deficient state to a hydrogen surplus state all at once, it is necessary to shift the external heat exchanger, the heat transfer fluid and its piping, and the MH tank from a high temperature state to a low temperature state. More time is required than the shift from.
[0008]
That is, the conventional fuel cell device with an MH tank that shifts the equilibrium pressure point of the hydrogen partial pressure of the MH tank only by the temperature change of the heat transfer fluid has a problem that the response of hydrogen compensation is slow.
The present invention has been made in view of the above problems, and has a fuel cell device with an MH tank that can reduce heat economy in heating and cooling the MH tank, and further improve the response of the hydrogen storage and release operations of the MH tank. Providing is a problem to be solved.
[0009]
[Means for Solving the Problems]
2. The fuel cell device according to claim 1, wherein the hydrogen storage alloy built-in tank (MH tank) disposed between the reformer and the fuel cell is at least a fuel of the fuel cell by adopting a compression means and a pressure regulation means. It is used at a pressure much higher than the working pressure of the electrode (at least 1 kg / square cmG or more in an equilibrium state where the hydrogen production rate of the reformer and the hydrogen consumption rate of the fuel cell coincide with each other). The amount of heat exchange for controlling the hydrogen storage / release operation is made based on the state quantity related to the difference between the reformer's hydrogen production rate and the fuel cell's hydrogen consumption rate.
[0010]
The compression means here refers to a pump that supplies raw fuel to the reformer as described in claim 3, or a hydrogen-containing gas produced from the reformer as described in claim 4. Means a compressor that
In this way, the following effects can be obtained.
First, in this configuration, since the compression means and the pressure adjusting means are used at a much higher pressure than the operating pressure of the fuel cell, the delay in response of the hydrogen storage and discharge operations of the MH tank can be improved.
[0011]
More specifically, it is assumed that the hydrogen consumption rate of the fuel cell suddenly increases and its operating pressure suddenly decreases. Then, the pressure adjusting means opens, the hydrogen-containing gas discharge rate from the MH tank to the fuel cell increases, and the pressure in the MH tank decreases. Then, according to this pressure drop, the hydrogen storage alloy in the MH tank releases hydrogen gas. At this point, since the heat transfer rate between the hydrogen storage alloy of the MH tank and the external heat source is not changed, the latent heat necessary for releasing the hydrogen gas at this time is mainly the hydrogen storage alloy and the heat transfer fluid. It is covered by the heat capacity such as the temperature drop (sensible heat). That is, the hydrogen storage alloy can release hydrogen gas until the temperature drop allowed by its heat capacity balances the pressure drop, and can respond to the increase in the hydrogen consumption rate of the fuel cell with good response. Of course, the limit of this pressure drop is when the MH tank pressure substantially matches the operating pressure of the fuel cell. Of course, the above-described response improvement effect also occurs when the hydrogen consumption rate of the fuel cell suddenly decreases and the operating pressure rapidly increases.
[0012]
Next, in this configuration, since the heat transfer amount of the MH tank is changed according to the data regarding the difference between the hydrogen consumption rate and the hydrogen production rate, in other words, the actual reformer and the fuel cell Since the MH tank is operated so as to compensate for the difference between both operating conditions, there is a mismatch between the hydrogen storage / release operation of the MH tank and the actual difference between the operating conditions of both the reformer and the fuel cell. There is an effect that it does not occur.
[0013]
That is, the hydrogen storage / release operation of the MH tank that changes relatively slowly changes according to the actual difference in the operating conditions of both the reformer and the fuel cell that change more slowly than the change in power, so mismatching occurs. Even if the hydrogen production rate of the reformer changes due to the occurrence of some trouble, it responds well to it, so the MH tank's hydrogen storage / release operation is changed by simply changing the power. Compared to the case, mismatching can be further reduced, and it is difficult to cause waste of thermal economy and surplus hydrogen gas in the fuel cell, which is efficient.
[0014]
According to the configuration of the second aspect, in the fuel cell device according to the first aspect, the control is further performed based on the pressure of the hydrogen storage alloy built-in tank, so that the control can be reliably performed with a simple configuration. it can.
According to the configuration described in claim 3, in the fuel cell device according to claim 1 or 2, the compression means is a liquid pump for supplying raw fuel to the reformer. If it does in this way, a compression means can be constituted easily and motive power required for compression can be reduced.
[0015]
According to the configuration of the fourth aspect, in the fuel cell device according to the first or second aspect, the compression means is a compressor between the reformer and the MH tank. In this way, the reformer can be operated at a low pressure even though the MH tank is used at a sufficiently high pressure as compared with the fuel cell, so that the weight can be reduced by reducing the pressure resistance of the reformer.
[0016]
According to the fifth aspect of the invention, in the fuel cell device of the third or fourth aspect, the compression means is further decelerated when the pressure of the hydrogen storage alloy built-in tank is higher than a predetermined pressure, and is accelerated when the pressure is low.
In this way, the hydrogen supply rate to the fuel cell can be followed at high speed even temporarily, in accordance with the change in the hydrogen consumption rate of the fuel cell.
[0017]
According to the structure of claim 6, in the fuel cell device according to any one of claims 2 to 5, the hydrogen production rate of the reformer is further reduced when the pressure of the hydrogen storage alloy built-in tank is higher than a predetermined pressure. Reduce and increase when low.
In this way, although slow, it is possible to reduce the difference between the hydrogen production rate and the hydrogen consumption rate and improve the efficiency.
[0018]
According to the configuration of claim 7, in the fuel cell device according to any one of claims 1 to 6, a bypass path for directly supplying the hydrogen-containing gas generated by the reformer to the fuel cell is provided, and a specific condition, for example, When the hydrogen production rate matches the hydrogen consumption rate, the hydrogen-containing gas from the reformer is supplied through the bypass circuit. In this way, the MH tank can be separated in the above-mentioned coincidence state, thereby preventing heat loss and the like, and controlling the MH tank to a preferable pressure state (for example, the hydrogen consumption rate of the fuel cell). When the amount of hydrogen stored is small, the hydrogen storage amount of the MH tank can be made large, or when the hydrogen consumption rate of the fuel cell is large, the hydrogen storage amount of the MH tank can be decreased.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The raw material of the reformer is not particularly limited as long as it can generate a hydrogen-containing gas. For example, methanol is preferable. In order to change the reformer's hydrogen production rate, the amount of heat generated by the combustor is controlled. At this time, the supply pressure of the raw material (for example, methanol or water) to the reformer is changed. Can also be controlled.
[0020]
As the pressure adjusting means, a simple mechanism such as a nozzle or a regulator for controlling the output pressure to be constant can be used.
A solid polymer electrolyte fuel cell is suitable for the fuel cell. It is economically common to supply excess air to the fuel cell cathode, and the operating pressure of the fuel cell is preferably set to a relatively low level in order to reduce its compression power. .
[0021]
[Example 1]
An embodiment of the fuel cell of the present invention for supplying driving power to a vehicle will be described with reference to FIG.
(Description of configuration)
Reference numeral 1 denotes a reformer (reformer), in which methanol stored in a methanol tank 2 is pressurized and supplied by a pump 3, and similarly, water stored in a water tank 4 is pumped. 5 is pressurized and supplied. The flow rates of the pumps 3 and 5 are controlled by changes in the number of revolutions according to the hydrogen production rate calculated and determined by the controller 6, and the maximum discharge pressure of both pumps 3 and 5 is 5 kg / square cmG or more. Preferably, it is set to about 5.5 kg / square cmG. The reformer 1 includes a combustor 11, and the heat generated in the combustor 11 vaporizes the raw material methanol and water to reform the hydrogen-containing gas mainly containing hydrogen. The produced hydrogen-containing gas is sent to an MH tank (hydrogen storage alloy built-in tank) 7 after the CO concentration is reduced by the converter 12 of the reformer 1.
[0022]
The MH tank 7 is composed of a pressure vessel in which a heat exchanger and a hydrogen storage alloy (not shown) are accommodated, and has a flow path for a hydrogen-containing gas inside. The hydrogen-containing gas that has flowed into the MH tank 7 is regulated to a predetermined reference pressure (here 1 kg / square cmG) through the regulator 8 while receiving and receiving hydrogen storage alloy and hydrogen, and flows into the fuel electrode of the fuel cell 9. To do.
[0023]
The fuel cell 9 generates water by generating a reaction by a reaction between a hydrogen-containing gas flowing into the fuel electrode and air flowing into the air electrode by a blower (not shown), and discharges exhaust gas in which hydrogen gas remains. Further, since the fuel cell 9 generates heat, water is circulated for cooling. In this embodiment, when hydrogen is released from the MH tank 7, hot water between the fuel cell 9 and the MH tank 7 is circulated by operating a circulation pump 16 described later, and heat generated by the fuel cell 9 is given to the MH tank 7. ing. When the MH tank 7 is not discharged with hydrogen, the heat generated by the fuel cell 9 is discharged to an external radiator by the operation of a circulation pump (not shown). Further, the exhaust gas of the fuel cell 9 is sent to the combustor 11 of the reformer 1 through a valve (not shown) and burned together with methanol. The electric power generated in the fuel cell 9 is supplied to the load through an electric circuit (not shown). The amount of heat generated by the combustor 11 is adjusted so as to be necessary and sufficient for processing the raw fuel supplied to the reformer 1 by the pumps 3 and 5.
[0024]
Reference numeral 15 denotes an external heat exchanger (radiator) with a fan. The cold water cooled by the external heat exchanger 15 is circulated with the switching valve 17, the circulation pump 16, the heat exchanger 71, and the external heat exchanger 15. Then, the hydrogen storage alloy is cooled. When the hydrogen storage alloy is heated, the water sent from the circulation pump 16 circulates through the heat exchanger 71, the fuel cell 9, and the switching valve 18 as described above to heat the hydrogen storage alloy.
[0025]
Reference numeral 20 denotes a pressure sensor that detects the pressure in the MH tank 7. In this embodiment, various controls are executed based on the pressure in the MH tank 7. The state quantity corresponding to the difference between the hydrogen production rate of the reformer 1 and the hydrogen consumption rate of the fuel cell 9 includes the temperature of the water circulating in the MH tank 7 in addition to the pressure of the MH tank 7. Etc.
(Description of basic operation)
Hereinafter, the basic operation of the fuel cell device will be described.
[0026]
The pumps 3 and 5 are driven, and the internal pressure of the fuel cell 9 is adjusted to 1 kg / square cm G by regulating the regulator 8, and the exhaust gas discharged from the fuel cell 9 is combustor 11 of the reformer 1. The reformer 1 produces a hydrogen-containing gas by the reforming reaction. In the initial stage of the reformer start-up until the reformer 1 starts up, the hot water generated by some method is sent to the MH tank 7 to compensate for the shortage of the hydrogen production rate of the reformer 1 to release hydrogen gas. The MH tank 7 is stored in the MH tank 7 to store the hydrogen gas in the hydrogen-containing gas produced from the reformer 1 when the operation of the reformer 1 after the operation of the fuel cell 9 is stopped. Cooling with the radiator 15 is possible.
(Description of control operation)
Next, capability control of the reformer 1, the MH tank 7, and the fuel cell 9 will be described. Of course, it is possible to perform these capability controls steplessly, but in this embodiment, in order to simplify the explanation and the control operation, it is assumed that multistage control is performed.
[0027]
(Control of reformer 1)
In order to simplify the control, the hydrogen production rate of the reformer 1 is displayed as a relative value, and is maximum (100% operation = 1), intermediate (50% operation = 0.5), stopped (0 This control is performed by adjusting the number of rotations of the pumps 3 and 5, that is, by adjusting the amount of raw fuel supplied to the reformer 1 in the above-mentioned three stages. The amount of heat generated by the combustor 11 of the machine 1 is also changed to the above three stages by adjusting the methanol supply amount. However, in this embodiment, in order to maintain the pressure of the MH tank 7 at a high pressure, the discharge pressure of the pumps 3 and 5 is at least the delivery pressure of the hydrogen-containing gas to the fuel cell 9 is 1 kg / square cmG or more. Then, it sets so that the pressure of an MH tank can reach 5.5 kg / square cmG at the maximum.
[0028]
(Control of MH tank 7)
Since the hydrogen storage / release rate of the MH tank 7 can be adjusted by the heat transfer amount of the MH tank, in this embodiment, the rotation speed of the circulation pump 16 is changed to three stages of full load operation, partial load operation, and stop. It shall be adjusted to 5 stages of 100% occlusion, 50% occlusion, stop, 50% release and 100% release.
[0029]
After all, assuming for the sake of simplicity that the amount of hydrogen exchanged at 100% occlusion or release of the MH tank 7 is equal to the maximum of the reformer 1, the combination of the operations of the reformer 1 and the MH tank 7 It can be seen that the hydrogen supply rate supplied from the fuel cell 7 to the fuel cell 9 can be adjusted in five steps of 2, 1.5, 1, 0.5, and 0 when expressed in relative values.
[0030]
(Control of fuel cell 9)
The power generation capacity (power that can be generated) of the fuel cell 9 is determined by the average hydrogen partial pressure of the fuel electrode of the fuel cell 9 and the average oxygen partial pressure of the air electrode of the fuel cell 9 adjusted correspondingly, These average partial pressures are related to the supply rate of hydrogen and oxygen supplied to these electrodes and the decrease rate of hydrogen and oxygen in these electrodes, and the former is from the MH tank 7 to the fuel cell 9. The latter is related to the actual power generation amount (water generation amount) of the fuel cell 9. Therefore, the power generation capacity of the fuel cell 9 is controlled by actively adjusting the flow rates of the hydrogen-containing gas and air into the fuel cell 9 according to the power generation situation (active mode), and the consumption of electric load. By changing the hydrogen partial pressure and oxygen partial pressure in the fuel cell 9 according to the electric power, that is, the actual power generation amount of the fuel cell 9, the inflow flow rates of the hydrogen-containing gas and air flowing into the fuel cell 9 are passively adjusted. There are two cases (passive mode). This will be described more specifically.
[0031]
First, the active mode will be described in more detail.
In the case where the actual power generation amount of the fuel cell 9, that is, the power consumption of the electric load, tends to increase and may exceed the power generation capacity defined by the current supply rate of hydrogen and oxygen to the fuel cell 9. Both hydrogen and oxygen supply rates to the fuel cell 9 are increased steplessly or stepwise to increase the power generation capacity of the fuel cell 9, and vice versa. Both the supply rates are decreased steplessly or stepwise to decrease the power generation capacity of the fuel cell 9. Active adjustment of the supply rate of hydrogen and oxygen to the fuel cell 9 is performed by opening a valve that controls the flow rate of exhaust gas discharged from the fuel cell 9 to the combustor 11 of the reformer 1. For example, when the power generation capacity of the fuel cell 9 is increased, if this valve is opened, the pressure of the fuel electrode of the fuel cell 9 decreases due to the increase of the exhaust gas flow rate, and the output pressure of the regulator 8 tends to decrease, and this is compensated. Therefore, the regulator 8 is opened to increase the flow rate of the hydrogen-containing gas, and the pressure of the fuel electrode of the fuel cell 9 is maintained at the reference pressure. Similarly, the air flow rate of a blower (not shown) that sends air to the air electrode of the fuel cell 9 is increased in accordance with the increase in the hydrogen-containing gas flow rate. The air flow rate of the blower may be set large in advance to simplify the control. When the power generation capacity of the fuel cell 9 is reduced, the reverse operation is performed, but the description thereof is omitted.
[0032]
Next, the passive mode will be described in more detail.
When the actual power generation amount of the fuel cell 9 increases, the average hydrogen partial pressure and the average oxygen partial pressure in the fuel cell 9 decrease, and the pressure of the fuel cell 9 decreases accordingly, so that the regulator 8 increases accordingly. Due to this compensation action, the supply rate of the hydrogen-containing gas from the MH tank 7 to the fuel cell 9 increases. If the air supply rate is set somewhat excessively in advance, the air supply rate on the air side does not have to be increased at the same rate as the supply rate of the hydrogen-containing gas, so control is simple or It becomes unnecessary. When the power generation amount of the fuel cell 9 is reduced, the reverse operation is performed, but the description thereof is omitted.
[0033]
The active control and the passive control may be performed together, but depending on the case, only the passive control may be performed. The electric load of the fuel cell 9 is a load that changes in three stages of 1 (100% operation), 0.5 (50% operation), and stop according to the adjustment of the hydrogen production rate of the reformer 1. Although particularly preferred, other arbitrarily variable electrical loads can also be used.
[0034]
When used in the system of this embodiment, the maximum hydrogen consumption rate of the fuel cell 9 is equal to the sum of the maximum hydrogen production rate of the reformer 1 and the maximum hydrogen release rate of the MH tank 7. In this embodiment, the maximum hydrogen production rate of reformer 1 is set to twice. The Yes. As a result, the fuel cell 9 is designed to have a power generation capacity that is twice as much as the power generation capacity corresponding to the hydrogen production rate of the reformer 1 under the operating conditions of this system.
[0035]
Next, an example of control of the reformer 1 and the MH tank 7 by the controller 6 with built-in microcomputer will be described below with reference to the flowchart of FIG.
First, the reformer 1 and the fuel cell 9 are set in a predetermined mode in advance. However, it is preferable that the hydrogen consumption rate of the fuel cell 9 is set to coincide with the hydrogen production rate of the reformer 1 at this initial point.
[0036]
Next, the pressure Pmh in the MH tank 7 is detected from the pressure sensor 20 (S100). As described above, the pressure Pmh in the MH tank 7 is generated by the change in the active or passive hydrogen consumption rate of the fuel cell 9 described above. Next, proceeding to S101, the MH tank 7 is controlled based on the detected pressure Pmh.
More specifically, when the pressure Pmh is less than 3.0 kg / square cmG, the process proceeds to S102, the pump 16 is driven at a capacity of 100%, the valve 17 is closed, the valve 18 is opened, and 100% of the heat is supplied. Hydrogen is generated from the MH tank 7 with 100% capacity.
[0037]
When the pressure Pmh is 3.0 to 3.5 kg / square cm G, the process proceeds to S103, the pump 16 is driven at a capacity of 50%, the valve 17 is closed, the valve 18 is opened, and 50% of hot heat is supplied to supply the MH tank. Generate hydrogen at 7 to 50% capacity.
When the pressure Pmh is 4.5 to 5.0 kg / square cm G, the process proceeds to S104, the pump 16 is driven at a capacity of 50%, the valve 17 is opened, the valve 18 is closed, and 50% of cooling water is supplied to the MH. Absorb hydrogen in tank 7 at 50% capacity.
[0038]
When the pressure Pmh is 5.0 kg / square cm G or more, the process proceeds to S105, the pump 16 is driven at a capacity of 100%, the valve 17 is opened, the valve 18 is closed, and 100% of cooling water is supplied by the MH tank 7. Absorbs hydrogen at 100% capacity.
In S101, when the pressure Pmh is in the range of 3.5 to 4.5 kg / square cm G, the hydrogen production rate of the reformer 1 matches the hydrogen consumption rate of the fuel cell 9 Return to S100.
[0039]
Next, in S102 and S103, since the hydrogen production rate of reformer 1 is smaller than the hydrogen consumption rate of fuel cell 9, the current hydrogen production rate of reformer 1 is 50%. Whether it is a rate or not is checked (S106). If so, the hydrogen production rate is changed to 100% (S107), and the process returns to S100. If the hydrogen production rate of the current reformer 1 is not 50% in S106, it is further checked whether the hydrogen production rate of the current reformer 1 is 0% (stop) (S108). If it is%, it increases to 50% (S109), and if it is 0%, it immediately returns to S100.
[0040]
Next, S104, S 1 In 05, since the hydrogen production rate of reformer 1 is larger than the hydrogen consumption rate of fuel cell 9, whether the current hydrogen production rate of reformer 1 is 100% rate or not. (S110), if so, the hydrogen production rate is changed to 50% (S111), and the process returns to S100. If the hydrogen production rate of the current reformer 1 is not 100% in S110, it is further checked whether the hydrogen production rate of the current reformer 1 is 50% (S112). If it is 0%, it immediately returns to S100.
[0041]
Since the actual change from the change command for the hydrogen production rate of the reformer 1 takes time, the control from S100 to S105 is actually repeated many times, and the change from S106 to S109 is performed. The increase control of the hydrogen production rate of the Ma 1 or the decrease control of the hydrogen production rate of the reformer 1 from S110 to S113 can be executed only once when a predetermined longer time elapses. preferable.
[0042]
[Example 2]
A fuel cell device according to a second embodiment which is a modification of the first embodiment will be described with reference to FIG.
This fuel cell apparatus is provided with a bypass path 30 for bypassing between the outlet of the reformer 1 and the inlet of the fuel cell 9 in the fuel cell apparatus of FIG. 1, and a regulator 31 is provided in the bypass path. A check valve 32 is provided between the reformer 1 and the MH tank 7, and a pressure sensor 33 is further provided at the outlet of the reformer 1.
[0043]
In this embodiment, an operation situation in which the hydrogen production rate of the reformer 1 and the hydrogen consumption rate of the fuel cell 9 coincide is detected, and if they coincide, the regulator 31 is opened and the reformer 1 is opened. The hydrogen-containing gas is supplied to the fuel cell 9 without passing through the MH tank 7.
In this way, useless pressure loss can be reduced, and the hydrogen storage state of the MH tank 7 can be easily maintained at an optimum level. When the bypass is started by the regulator 31, the pressure sensor 20 may not follow the difference between the hydrogen production rate and the hydrogen consumption rate due to the presence of the check valve 32. The control 2 can be performed based on the pressure sensor 33. Alternatively, in this embodiment, the pressure sensor 20 may be used for emergency detection, and the control in FIG.
[0044]
[Example 3]
A fuel cell device according to a third embodiment which is a modification of the first embodiment will be described with reference to FIG.
This fuel cell device is the same as the fuel cell device of FIG. 1 except that a compressor 34 is provided between the reformer 1 and the MH tank 7. The compressor 34 is operated to increase the pressure of the MH tank 7 when supplying hydrogen to the fuel cell 9.
[0045]
In this way, the reformer 1 can be operated at a much lower pressure than in the first embodiment, so that the size and weight can be reduced by reducing the pressure resistance.
FIG. 5 is a combination of the second and third embodiments, and the effects of both the embodiments can be achieved.
[Brief description of the drawings]
FIG. 1 is a block diagram of a fuel cell device according to Embodiment 1 of the present invention.
2 is a flowchart showing control of the reformer 1 and the MH tank 7 of the fuel cell apparatus of FIG. 1;
FIG. 3 is a block diagram of a fuel cell device according to Embodiment 2 of the present invention.
FIG. 4 is a block diagram of a fuel cell device according to Embodiment 3 of the present invention.
FIG. 5 is a block diagram of a fuel cell apparatus according to Embodiment 4 of the present invention.
[Explanation of symbols]
1 is a reformer, 3 is a pump (compression means), 5 is a pump (compression means), 6 is a controller (control means), 7 is a hydrogen storage alloy built-in tank (MH tank), 8 is a regulator ( Pressure adjusting means), 9 is a fuel cell, and 20 is a pressure sensor (detecting means).

Claims

A reformer that produces a hydrogen-containing gas from the supplied raw material, a fuel cell that generates power using the supplied hydrogen-containing gas, and a hydrogen storage alloy that is interposed between the reformer and the anode of the fuel cell. In a fuel cell power generator comprising a hydrogen storage alloy built-in tank, and an external heat source for transferring heat to and from the hydrogen storage alloy built-in tank,
Compression means for holding the internal pressure of the hydrogen storage alloy built-in tank at a predetermined pressure or higher than the operating pressure of the fuel electrode of the fuel cell;
Pressure adjusting means for adjusting the pressure of the hydrogen-containing gas supplied from the hydrogen storage alloy built-in tank to the fuel cell to the operating pressure;
Detecting means for detecting a state quantity related to a difference between a hydrogen production amount of the reformer and a hydrogen consumption amount of the fuel cell;
A fuel cell device comprising: control means for controlling the amount of heat exchange between the hydrogen storage alloy built-in tank and the external heat source based on the state quantity to suppress the pressure change of the hydrogen storage alloy built-in tank.

The fuel cell device according to claim 1, wherein
The control means commands cooling supply to the hydrogen storage alloy built-in tank when the pressure of the hydrogen storage alloy built-in tank forming the state quantity is higher than a predetermined pressure, and the pressure of the hydrogen storage alloy built-in tank is set to a predetermined pressure. A fuel cell device that commands the supply of heat to the hydrogen storage alloy built-in tank when the temperature is lower.

The fuel cell device according to claim 1 or 2,
The fuel cell device characterized in that the compression means comprises a liquid pump for supplying raw fuel to the reformer.

The fuel cell device according to claim 1 or 2,
The fuel cell device characterized in that the compression means comprises a compressor interposed between the reformer and the hydrogen storage alloy built-in tank.

The fuel cell device according to claim 3 or 4,
The control means decelerates the compression means when the pressure of the hydrogen storage alloy built-in tank forming the state quantity is higher than a predetermined pressure, and the compression means when the pressure of the hydrogen storage alloy built-in tank is lower than a predetermined pressure. A fuel cell device characterized by accelerating the operation.

The fuel cell device according to any one of claims 2 to 5,
The control means reduces the hydrogen production rate of the reformer when the pressure of the hydrogen storage alloy built-in tank forming the state quantity is higher than a predetermined pressure, and the pressure of the hydrogen storage alloy built-in tank is set to a predetermined pressure. A fuel cell device characterized by increasing the hydrogen production rate when the temperature is lower.

The fuel cell device according to any one of claims 1 to 6,
A bypass path for supplying the hydrogen-containing gas produced by the reformer directly to the fuel cell;
A fuel cell device comprising switching means for switching between the bypass circuit and a supply path to the hydrogen storage alloy built-in tank.

The fuel cell device according to claim 1, wherein
The control means controls the amount of heat exchange between the hydrogen storage alloy built-in tank and the external heat source based on the state quantity during the period in which the reformer is producing a hydrogen-containing gas, thereby controlling the pressure of the hydrogen storage alloy built-in tank. A fuel cell device that suppresses a change.

The fuel cell device according to claim 1, wherein
The pressure adjusting means controls the amount of heat exchange between the hydrogen storage alloy built-in tank and the external heat source based on the state quantity, and suppresses the pressure change in the hydrogen storage alloy built-in tank. A fuel cell device, wherein the pressure of a hydrogen-containing gas supplied from the hydrogen storage alloy built-in tank to the fuel cell is adjusted to the operating pressure.