JP3761217B2

JP3761217B2 - Fuel cell system

Info

Publication number: JP3761217B2
Application number: JP10031195A
Authority: JP
Inventors: 良和遠畑; 厚至工匠
Original assignee: Aisin Seiki Co Ltd; Toyota Motor Corp; Aisin Corp
Current assignee: Toyota Motor Corp; Aisin Corp
Priority date: 1995-03-31
Filing date: 1995-03-31
Publication date: 2006-03-29
Anticipated expiration: 2021-03-29
Also published as: JPH08273689A

Description

【０００１】
【産業上の利用分野】
本発明は、水素リッチガスと酸素含有ガスとを燃料ガスとして供給を受け電極反応を起こす燃料電池を有する燃料電池システムに関する。
【０００２】
【従来の技術】
水素リッチガスを燃料ガスとする燃料電池は、水素イオンをＨ⁺（_xＨ₂Ｏ）の水和状態で透過する電解質と電極とを有し、電極での反応を促進させるための触媒層を介在させてこの電解質を電極で挟持して備える。このような燃料電池は、用いる電解質の種類により種々のもの（例えば、固体高分子型燃料電池，りん酸型燃料電池等）があるが、アノード，カソードの両電極において進行する電極反応は、以下の通りである。
【０００３】
アノード：２Ｈ₂→４Ｈ⁺＋４ｅ^- …▲１▼
カソード：４Ｈ⁺＋４ｅ^-＋Ｏ₂→２Ｈ₂Ｏ …▲２▼
【０００４】
そして、アノードに水素ガスが供給されると、アノードでは▲１▼の反応式が進行して水素イオンが生成する。この生成した水素イオンがＨ⁺（_xＨ₂Ｏ）の水和状態で電解質（固体高分子型燃料電池であれば固体高分子電解質膜）を透過（拡散）してカソードに至り、このカソードに酸素含有ガス、例えば空気が供給されていると、カソードでは▲２▼の反応式が進行する。この▲１▼，▲２▼の電極反応が各極で進行することで、燃料電池は起電力を呈することになる。
【０００５】
上記の▲２▼の電極反応から明らかなように、燃料電池で電池反応が起きるとカソードでは水が生成されるので、生成水がカソードに留まったままでは▲２▼の電極反応の進行が阻害される。このため、電極反応の進行の円滑化、延いては発電効率の向上を図る上から、この生成水はカソードから燃料電池の外部に常時放出されている。ところで、この生成水は、水素と酸素との化学反応から生成されるので比較的その純度が高い。よって、この生成水を再利用する技術が種々提案されている。例えば、特開平５−２１０８０では、燃料電池で生成した生成水を改質装置への供給水を貯留する水タンクに回収し、生成水を循環利用する技術が提案されている。
【０００６】
【発明が解決しようとする課題】
燃料電池は、ＮＯｘ等の環境に好ましくないガスをエネルギ取得に際して放出しない。よって、環境保護の観点から、燃料電池は、大型プラントとしての発電プラントや、内燃機関に替わる車両等のエネルギ源として急速に普及しつつある。この場合、発電プラントであれば、燃料電池はもとより改質装置にあってもいわゆる終日運転され、その運転停止は、プラントの保守・点検時等にのみ行なわれるに過ぎない。このため、燃料電池での生成水は、その循環経路にて常時流通しており、経路にて留まることはない。これに対して、燃料電池を車両等に搭載してエネルギ源として用いた場合には、燃料電池の運転・停止は頻繁に行なわれる。このため、車両等にあっても生成水を循環利用する際には、燃料電池での生成水は、燃料電池の運転停止時に循環経路に滞留したり、当該経路における水タンクに貯留されたままとなる。
【０００７】
従って、車両等が寒冷地に移動した場合や、或いは寒冷地での車両等の使用に際しては、運転停止時において経路や水タンクの生成水が凍結することがある。このため、経路が閉塞したり水タンクから水を送り出すことができなくなる虞がある。このような事態に到ると、生成水をカソードから燃料電池の外部に放出できなくなる。よって、改質装置にて生成した水素ガスと空気との供給を開始して電極反応を起こさせようとしても、凍結による経路の閉塞等が解消するまではカソードから燃料電池の外部に生成水を放出できないので、カソードでの電極反応の進行が阻害される。よって、燃料電池、延いては燃料電池システムとしての始動性が低下する。
【０００８】
もっとも、この始動性の低下は、燃料電池で生成した生成水を循環利用する際に特有のものではなく、当該生成水をただ単に燃料電池の外部に放出するだけの場合にも生じる。つまり、この放出のためだけの経路（管路）で生成水の凍結が生じても、上記した理由により始動性は低下する。
【０００９】
本発明は、上記問題点を解決するためになされ、燃料電池を有する燃料電池システムの始動性の向上を図ることを目的とする。
【００１０】
【課題を解決するための手段】
かかる目的を達成するための本発明の燃料電池システムで採用した手段は、
炭化水素化合物と水との供給を受け、該供給を受けた炭化水素化合物を改質反応に供して水素リッチガスを生成する改質装置と、該生成した水素リッチガスと酸素含有ガスとを燃料ガスとして供給を受け電極反応を起こす燃料電池とを有する燃料電池システムであって、
前記改質装置が有する加熱器の排ガスを該改質装置外に導く排出系統と、
前記電極反応に伴う生成水を前記燃料電池外に導く水系統とを備え、
前記排出系統は、前記水系統との間で熱交換を行なう熱交換部を有し、
前記水系統は、前記生成水を貯留する生成水貯留部と、前記燃料電池から該生成水貯留部までの第１水系統部と、前記炭化水素化合物と水とを混合して前記改質装置に供給するための改質材料タンク部と、前記生成水貯留部から前記改質材料タンク部までの第２水系統部とを有する水循環系とし、前記生成水貯留部、前記第１水系統部、第２水系統部のそれぞれを、前記排出系統と熱交換するよう備えること
をその要旨とする。
【００１３】
上記した本発明の燃料電池システムでは、更に、
前記排出系統に設けられ、前記改質装置が有する加熱器の前記排ガスの排出先を、前記排ガスをシステム外部に導く外部解放系と前記熱交換部のいずれかに切り換える切換手段と、
前記水系統における水の凍結の可能性を判定する凍結判定手段と、
該判定結果に応じて、前記切換手段を切換制御する制御手段とを備えるようにすることもできる。
また、前記排出系統を、前記第１水系統部、第２水系統部と接して直接熱交換し、熱交換器を介して前記生成水貯留部と間接的に熱交換するものとすることもできる。
更に、前記排出系統を、前記第１水系統部、第２水系統部と接して直接熱交換すると共に、
前記生成水貯留部を螺旋状に取り囲んで該生成水貯留部と直接熱交換するようにすることもできる。
また、改質装置に水と共に供給する炭化水素化合物をメタノールとした上で、そのメタノールと水とを前記改質装置に供給する改質材料供給経路を備えるものとし、前記切換手段により前記改質装置が有する加熱器の前記排ガスの排出先が前記外部解放系に切り換えられたときには、前記外部解放系と前記改質材料供給経路との間で熱交換するようにすることもできる。
【００１４】
【作用】
以上した構成を有する本発明の燃料電池システムでは、改質装置が有する加熱器の排ガスを装置外に導く排出系統の有する熱交換部により水系統との間で熱交換を行なうので、改質装置が始動して起きる改質反応に伴う排ガスの熱エネルギを水系統に与える。よって、運転停止時に水系統にて生成水の凍結が起きていても、排ガスの熱エネルギにより速やかに水系統における凍結状態を解消する。
しかも、水系統の有する生成水貯留部と第１水系統部と第２水系統部とを有する水循環系に排ガスの熱エネルギを与えるので、運転停止時にこの水循環系のいずれかの箇所で生成水の凍結が起きていても、排ガスの熱エネルギによる速やかな凍結状態の解消を通して、早期に水循環を図る。
【００１７】
そして、凍結判定手段により水系統における水の凍結の可能性を判定し、その結果に応じて制御手段により切換手段を切換制御するので、排ガスの排出先は外部解放系と熱交換部のいずれかに切り換えられる。よって、生成水の凍結の可能性があれば排ガスを熱交換部に導いて排ガスの熱エネルギを凍結状態の解消に用い、凍結の可能性がない或いは低いのであれば排ガスを外部解放系に導き排ガスの熱エネルギを他の用途に供することができる。
また、前記排出系統を、前記第１水系統部、第２水系統部と接して直接熱交換し、熱交換器を介して前記生成水貯留部と間接的に熱交換するものとしたり、前記生成水貯留部を螺旋状に取り囲んで該生成水貯留部と直接熱交換するようにすれば、排出系統を介してその熱エネルギにより第１水系統部、第２水系統部と生成水貯留部での凍結解消を図る。
また、改質装置に水と共に供給する炭化水素化合物をメタノールとした上で、そのメタノールと水とを前記改質装置に供給する改質材料供給経路を備えるものとし、前記切換手段により前記改質装置が有する加熱器の前記排ガスの排出先が前記外部解放系に切り換えられたときには、前記外部解放系と前記改質材料供給経路との間で熱交換するようにすれば、改質材料供給経路内のメタノールおよび水を予め昇温できる。
【００１８】
【実施例】
以上説明した本発明の構成・作用を一層明らかにするために、以下本発明の好適な実施例について説明する。図１は、実施例の燃料電池システム１０の構成の概略を例示するブロック図である。図示するように、燃料電池システム１０は、改質材料であるメタノールと水とを所定のモル比で混合して貯留する改質材料タンク１２と、メタノールを水蒸気改質して水素リッチガス（以下、単に水素ガスという）を生成する改質装置２０と、水素と酸素との反応を経て起電力を呈する固体高分子型燃料電池（以下、単に燃料電池と略称する）４０とを備える。
【００１９】
燃料電池４０は、固体高分子電解質膜４０ａをアノード４０ｂとカソード４０ｃの陽陰の電極で挟持して備え、カソード４０ｃへは酸素ガス供給管路４２から空気を、アノード４０ｂへは水素ガス供給管路４４から水素ガスの供給を受ける。そして、燃料電池４０は、上記の▲１▼，▲２▼の電極反応を陽陰の電極で進行させて起電力を呈し、図示しない配線を介して外部の駆動機器、例えば電気自動車におけるモータを駆動する。
【００２０】
改質装置２０は、メタノール改質用の触媒（例えば、Ｃｕ−Ｚｎ触媒等）を担持した担体が充填された改質器２２と、この改質器２２をメタノールの改質反応に適した温度（約２５０〜３００℃）に加熱する加熱器２４とを備える。改質器２２は、圧送ポンプ１４により改質材料タンク１２から改質材料供給経路１５を経てメタノールと水との供給を受ける。そして、この改質器２２は、改質触媒を介してメタノールの改質反応を進行させてメタノールを水蒸気改質し、水素ガスを生成する。この生成された水素ガスは、水素ガス供給管路４４に送り出される。加熱器２４は、アノード４０ｂで電極反応に消費されなかった余剰水素ガス中の水素とメタノールとを燃焼させ、改質器２２を加熱する。この余剰水素ガスは、燃料電池４０からの余剰ガス還流管路２６から、メタノールは、燃焼用のメタノールタンク２８から圧送ポンプ３０により、それぞれ加熱器２４に供給される。
【００２１】
燃料電池４０と改質装置２０との間の水素ガス供給管路４４の管路には、管路の水素ガス中の一酸化炭素を低減するためのＣＯシフト器４６とＣＯ変成器４８とが設けられている。ＣＯシフト器４６は、一酸化炭素を水と反応させて水素と二酸化炭素とを生成して、通過するガス中の、この場合には水素ガス中の一酸化炭素を低減する。そして、このＣＯシフト器４６への水の供給は、後述の生成水循環管路５０から分岐した分岐管路５２のポンプ５４を介して行なわれる。また、ＣＯ変成器４８は、微量の一酸化炭素であっても酸素の存在下で二酸化炭素に酸化する触媒（例えば、Ｒｕ触媒やＰｔ触媒等）を担持した担体を備え、通過する水素ガス中の一酸化炭素を更に低減する。なお、ＣＯ変成器４８へは、空気導入管５６から空気が導入され、空気中の酸素が一酸化炭素の酸化に用いられる。また、ＣＯシフト器４６やＣＯ変成器４８は、一酸化炭素の低減に必要な反応に適した温度に維持される。
【００２２】
このほか、燃料電池システム１０は、カソード４０ｃでの電極反応で生成した生成水を燃料電池４０外部に放出するための生成水放出管路６０を、燃料電池４０とその外部の生成水貯留タンク６２との間に備える。従って、燃料電池４０の電極反応に伴いカソードで生成した生成水は、生成水放出管路６０の管路途中の気液分離装置６１にてガス（カソードでの余剰空気）と分離されて生成水貯留タンク６２に到り、当該タンクに貯留される。また、燃料電池システム１０は、この生成水貯留タンク６２と改質材料タンク１２との間に生成水循環管路５０を備え、当該管路のポンプ６４により、生成水貯留タンク６２内の生成水を改質材料タンク１２に循環させる。よって、この生成水は、改質装置２０に再度送られてメタノールの改質に利用される。なお、気液分離装置６１で生成水と分離されたガス（空気）は、解放管６３から大気中に放出される。
【００２３】
更に、燃料電池システム１０は、加熱器２４でのメタノールおよび余剰水素ガス中の水素の燃焼によって生じる排ガスを、改質装置２０から当該装置外に導く排ガス導入経路７０を備える。この排ガス導入経路７０は、生成水循環管路５０と分岐管路５２の各管路に亘って形成され、図１の２−２線断面図である図２に示すように、これら各管路を取り囲む排ガス導入経路部７２と、生成水放出管路６０を含んだ領域として形成された排ガス導入貯留室部７４とを備える。従って、排ガス導入経路７０と生成水循環管路５０，分岐管路５２および生成水放出管路６０とは、直接熱交換される。
【００２４】
排ガス導入貯留室部７４と生成水貯留タンク６２とに亘っては、熱交換器７８が設けられている。この熱交換器７８は、排ガス導入貯留室部７４と生成水貯留タンク６２とに熱交換部を備え、両熱交換部の間に熱交換媒体（オイル・フルード系又はアルコール系のクーラント液）の導管７９を有する。従って、この熱交換器７８により、排ガス導入経路７０の排ガス導入貯留室部７４と生成水貯留タンク６２とは、熱交換される。なお、排ガス導入経路７０は、改質装置２０から離間した適宜箇所、本実施例では気液分離装置６１の近傍に、排ガス放出口７６を備える。
【００２５】
改質装置２０近傍の排ガス導入経路７０には、当該経路から分岐した排ガス分岐導入経路８０が設けられており、その分岐箇所には、両経路のいずれかに排ガスの排出先を切り換える切換バルブ８２が設けられている。
【００２６】
排ガス分岐導入経路８０は、燃料電池システム１０の通常運転時には改質装置２０の排ガスをシステム外部に導くためのものであり、経路の末端は排ガス放出口８４とされている。また、排ガス分岐導入経路８０の一部は、圧送ポンプ１４の下流にて改質材料供給経路１５を取り囲む排ガス導入経路部８６とされており、この排ガス導入経路部８６で、排ガス分岐導入経路８０と改質材料供給経路１５とは直接熱交換される。
【００２７】
また、燃料電池システム１０は、マイクロコンピュータを中心とする論理演算回路として構成された制御装置９０を備える。制御装置９０は、生成水貯留タンク６２内に設置されてタンク内の水の温度を検出する水温センサ９２やそのほかの図示しないセンサやスイッチからの信号を入力し、これら入力信号と予め設定された制御プログラムに従って圧送ポンプ１４，切換バルブ８２等を駆動制御する。
【００２８】
次に、燃料電池システム１０が行なう改質装置２０の排ガス排出処理について、図３のフローチャートに基づいて説明する。図３のフローチャートは、燃料電池システム１０の運転開始スイッチ、例えば車両のイグニッションスイッチがＯＮされると、電源投入時のみに実行されるＣＰＵの内部レジスタのリセット等の初期処理に続いて実行される。まず、処理が開始されると、水温センサ９２からの検出水温αｔを読み込み、その値と所定の比較水温αとの比較を行なう（ステップＳ１００）。この比較水温αは、生成水貯留タンク６２内の生成水が凍結する温度（ゼロ℃）に予め設定されているので、ステップＳ１００での比較により、生成水貯留タンク６２を始めとする生成水循環管路５０，分岐管路５２および生成水放出管路６０の生成水の水系統における凍結有無若しくは凍結の可能性の有無が判別される。
【００２９】
ここで、肯定判別、即ち生成水の水系統にて凍結がある若しくはその可能性があると判別した場合には、切換バルブ８２に制御信号を出力して改質装置２０の排ガスの排出先を排ガス導入経路７０に切り換える（ステップＳ１１０）。これにより、改質装置２０から排出される排ガスは、排ガス導入経路７０内の隅々に導入され、排ガス導入貯留室部７４を経て排ガス放出口７６から外部に排出される。従って、排ガス導入経路７０の排ガス導入経路部７２で取り囲まれた生成水循環管路５０や分岐管路５２と排ガス導入貯留室部７４における生成水放出管路６０では、この導入された排ガスと直接熱交換される。また、生成水貯留タンク６２では、熱交換器７８により排ガスと熱交換される。そして、ステップＳ１００で否定判別されるまで、切換バルブ８２の上記切り換えが継続され、排ガスは排ガス導入経路７０に導入され続ける。
【００３０】
一方、ステップＳ１００で否定判別、即ち生成水の水系統にて凍結がない若しくはその可能性がない或いは凍結が解消したと判別した場合には、切換バルブ８２に制御信号を出力して排ガスの排出先を排ガス分岐導入経路８０に切り換える（ステップＳ１２０）。これにより、排ガスは、排ガス分岐導入経路８０，排ガス導入経路部８６に導入され、排ガス放出口８４から外部に排出される。従って、排ガス導入経路部８６で取り囲まれた改質材料供給経路１５では、この導入された排ガスと直接熱交換される。そして、ステップＳ１００での否定判別が継続される間に亘って切換バルブ８２での切り換え状態は上記したように維持されるので、排ガスは排ガス分岐導入経路８０に導入され続ける。
【００３１】
ところで、燃料電池システム１０の運転開始スイッチ（イグニッションスイッチ等）のＯＮ操作と共に、図示しない制御プログラムに従って圧送ポンプ１４，３０はその直後から駆動され、改質装置２０の改質器２２へはメタノールと水とが改質材料タンク１２から供給され、加熱器２４へはメタノールタンク２８からメタノールが供給される。このため、改質装置２０からは、運転当初から高温の排ガスが排出され、その排出先は、上記したように切り換えられる。
【００３２】
以上説明した実施例の燃料電池システム１０では、システムの運転開始当初に水温センサ９２の検出水温から水の凍結がある或いは凍結の可能性がある場合には、排ガス導入経路７０に改質装置２０からの排ガスを導入し、生成水が通過する生成水放出管路６０，生成水循環管路５０および分岐管路５２と生成水が貯留される生成水貯留タンク６２の水系統を、排ガスとの間で熱交換可能とする。従って、実施例の燃料電池システム１０では、システムの停止期間中に生成水の水系統にて凍結が起きても、排ガスの熱エネルギを水系統に与えて凍結を速やかに解消する。この結果、本実施例の燃料電池システム１０によれば、凍結による水系統の管路の閉塞等の速やかな解消を通して燃料電池４０の外部に生成水を即座に放出できるので、始動時からのカソード４０ｃでの電極反応の円滑な進行を通して燃料電池システム１０の始動性を向上させることができる。
【００３３】
また、生成水が通過する管路である生成水循環管路５０，分岐管路５２および生成水放出管路６０については、排ガス導入経路部７２を通して直接排ガスと熱交換する。よって、これら管路では、より速やかに凍結を解消できる。
【００３４】
しかも、燃料電池システム１０では、生成水循環管路５０，分岐管路５２等の水系統に与える熱エネルギを改質装置２０からの排ガスで賄う。よって、この燃料電池システム１０によれば、別個の熱源の省略を通した構成の簡略化と、システムの熱効率の向上とを図ることができる。更には、排ガスによる解凍の間における駆動機器は圧送ポンプ１４，３０と切換バルブ８２に過ぎない。よって、燃料電池システム１０によれば、運転停止期間中にバッテリの放電が進んでその残存電気量が少ない場合でも、これら機器の駆動と排ガスによる解凍により、確実に且つ早期の内に燃料電池４０、延いては燃料電池システム１０を始動することができる。
【００３５】
また、燃料電池システム１０によれば、生成水放出管路６０等の上記管路や生成水貯留タンク６２での凍結の速やかな解消により、生成水貯留タンク６２内の生成水を早期のうちに改質材料タンク１２に送り出して再利用することができる。
【００３６】
更に、燃料電池システム１０では、生成水循環管路５０等の水系統における凍結が解消されたり凍結が起きていないような場合には、換言すれば燃料電池４０を始めとする燃料電池システム１０の定常運転時には、排ガス分岐導入経路８０の排ガス導入経路部８６を介した排ガスとの熱交換により、改質材料供給経路１５内のメタノールおよび水を改質器２２に到る前に予め昇温する。従って、燃料電池システム１０によれば、改質器２２におけるメタノールの改質反応の円滑な進行を通して改質器２２での反応効率、延いてはシステムの運転効率を向上することができる。
【００３７】
以上本発明の実施例について説明したが、本発明はこうした実施例に何等限定されるものではなく、本発明の要旨を逸脱しない範囲内において、種々なる態様で実施し得ることは勿論である。
【００３８】
例えば、改質材料タンク１２に替えてメタノールタンクと水タンクとを用い、これら各タンクから改質装置２０にメタノールと水とを供給する構成を採ることもできる。この場合であっても、それぞれのタンクから改質装置２０に到る管路を排ガスにて暖めれば、改質反応に関与するメタノールと水とを予め昇温でき改質反応の効率を高めることができる。
【００３９】
また、排ガス導入経路７０を、生成水貯留タンク６２を螺旋状に取り囲み当該タンクと直接熱交換する排ガス導入螺旋経路を有するものとすることもできる。このようにすれば、熱交換器７８が不要となり、部品点数の低減とそれに伴うコスト低減、延いては軽量化が可能である。
【００４０】
また、切換バルブ８２を水温センサ９２の検出した生成水貯留タンク６２内の水温で切り換え制御するよう構成したが、これに限るわけではない。例えば、燃料電池システム１０周辺の環境温度（大気温度）を検出し、その温度に応じて切換バルブ８２を切り換え制御する構成を採ることもできる。更には、運転者等が操作するマニュアルスイッチ（例えば、生成水の凍結が予想される際に運転者等によりＯＮとされるスイッチ）の操作状況に応じて切換バルブ８２を切り換え制御する構成を採ることもできる。
【００４１】
また、生成水の凍結の有無等を判別する際の比較水温αは、ゼロ℃に固定する必要はなく、燃料電池システム１０の使用環境の大気圧等に応じて可変とするよう構成することもできる。更には、燃料電池システム１０では、比較水温αとの比較結果に応じて切換バルブ８２を切り換え制御し排ガスの排出先を切り換えるよう構成したが、排ガスを始動当初から引き続き排ガス導入経路７０にのみ導入するようにして、排ガスとの熱交換を生成水循環管路５０，分岐管路５２，生成水貯留タンク６２等の生成水の水系統のみについて常時おこなう構成を採ることもできる。
【００４２】
【発明の効果】
以上説明したように本発明の燃料電池システムでは、電極反応に伴う生成水を燃料電池外に導く水系統において生成水の凍結が起きても、水系統に熱エネルギを与えることで速やかにその凍結状態を解消する。この結果、本発明の燃料電池システムによれば、凍結による水系統の管路の閉塞等の速やかな解消を通して燃料電池の外部に生成水を即座に放出できるので、始動時からのカソードでの電極反応の円滑な進行を通して燃料電池システムの始動性を向上させることができる。
しかも、本発明の燃料電池システムでは、水系統に与える熱エネルギを改質装置が有する加熱器の排ガスで賄うので、別個の熱源の省略を通した構成の簡略化と、システムの熱効率の向上とを図ることができる。
更には、水系統の有する生成水貯留部と第１水系統部と第２水系統部とを有する水循環系に排ガスの熱エネルギを与えるので、運転停止時にこの水循環系のいずれかの箇所で生成水の凍結が起きていても、凍結による生成水の水循環系の速やかな凍結状態の解消を通して早期に水循環を確保でき、早期のうちに生成水の再利用を図ることができる。
【００４５】
また、水系統の凍結の可能性の有無に応じて排ガスの排出先を切り換えて、排ガスの有する熱エネルギの供給先を、生成水の水系統と排ガスをシステム外部に導く外部解放系のいずれかとしたので、凍結状態の速やかな解消を通して燃料電池システムの始動性を向上できるばかりか、外部解放系での熱エネルギの有効利用を図ることができる。
また、排出系統と第１水系統部、第２水系統部との直接の熱交換や、排出系統と生成水貯留部との熱交換器を介した間接的な熱交換、或いは生成水貯留部を螺旋状に取り囲む排出系統による生成水貯留部の直接の熱交換により、第１水系統部、第２水系統部と生成水貯留部での凍結解消を図ることができる。特に、排出系統を生成水貯留部を螺旋状に取り囲むようにすれば、熱交換器が不要となり、部品点数の低減とそれに伴うコスト低減、延いては軽量化が可能である。
また、改質装置に水と共に供給する炭化水素化合物をメタノールとした上で、そのメタノールと水とを前記改質装置に供給する改質材料供給経路を備えるものとし、改質装置が有する加熱器の排ガスの排出先が外部解放系に切り換えられたときには、外部解放系と改質材料供給経路との間で熱交換するようにしたので、この改質材料供給経路内のメタノールおよび水を予め昇温できる。そして、昇温済みのメタノールと水とが供給される改質装置においては、メタノールの改質反応を円滑に進行させることができ、これにより、改質装置での反応効率、延いてはシステムの運転効率を向上することができる。
【図面の簡単な説明】
【図１】実施例の燃料電池システム１０の構成の概略を例示するブロック図。
【図２】図１の２−２線断面図。
【図３】燃料電池システム１０が行なう改質装置２０の排ガス排出処理を表わすフローチャート。
【符号の説明】
１０…燃料電池システム
１２…改質材料タンク
１４，３０…圧送ポンプ
１５…改質材料供給経路
２０…改質装置
２２…改質器
２４…加熱器
２６…余剰ガス還流管路
２８…メタノールタンク
４０…燃料電池
４０ａ…固体高分子電解質膜
４０ｂ…アノード
４０ｃ…カソード
４２…酸素ガス供給管路
４４…水素ガス供給管路
４６…ＣＯシフト器
４８…ＣＯ変成器
５０…生成水循環管路
５２…分岐管路
５４…ポンプ
５６…空気導入管
６０…生成水放出管路
６１…気液分離装置
６２…生成水貯留タンク
６３…解放管
６４…ポンプ
７０…排ガス導入経路
７２…排ガス導入経路部
７４…排ガス導入貯留室部
７６…排ガス放出口
７８…熱交換器
７９…導管
８０…排ガス分岐導入経路
８２…切換バルブ
８４…排ガス放出口
８６…排ガス導入経路部
９０…制御装置
９２…水温センサ[0001]
[Industrial application fields]
The present invention relates to a fuel cell system having a fuel cell that is supplied with hydrogen-rich gas and oxygen-containing gas as fuel gas to cause an electrode reaction.
[0002]
[Prior art]
A fuel cell using hydrogen-rich gas as a fuel gas uses hydrogen ions as H ⁺ ( _x H ₂ It has an electrolyte that permeates in the hydrated state of O) and an electrode, and this electrolyte is sandwiched between electrodes by interposing a catalyst layer for promoting a reaction at the electrode. There are various types of fuel cells depending on the type of electrolyte used (for example, solid polymer fuel cells, phosphoric acid fuel cells, etc.). The electrode reactions that proceed in both the anode and cathode electrodes are as follows. It is as follows.
[0003]
Anode: 2H ₂ → 4H ⁺ + 4e ^- … ▲ 1 ▼
Cathode: 4H ⁺ + 4e ^- + O ₂ → 2H ₂ O… ▲ 2 ▼
[0004]
When hydrogen gas is supplied to the anode, the reaction formula (1) proceeds at the anode and hydrogen ions are generated. The generated hydrogen ions are H ⁺ ( _x H ₂ O) is hydrated and permeates (diffuses) the electrolyte (solid polymer electrolyte membrane in the case of a polymer electrolyte fuel cell) to reach the cathode, and oxygen-containing gas such as air is supplied to the cathode. The reaction formula (2) proceeds at the cathode. As the electrode reactions (1) and (2) proceed at each electrode, the fuel cell exhibits an electromotive force.
[0005]
As is apparent from the electrode reaction (2) above, when a cell reaction occurs in the fuel cell, water is generated at the cathode, so if the generated water remains at the cathode, the progress of the electrode reaction (2) is hindered. Is done. For this reason, the generated water is constantly discharged from the cathode to the outside of the fuel cell in order to facilitate the progress of the electrode reaction and thus improve the power generation efficiency. By the way, since this produced water is produced from a chemical reaction between hydrogen and oxygen, its purity is relatively high. Therefore, various techniques for reusing the generated water have been proposed. For example, Japanese Patent Laid-Open No. 5-21080 proposes a technique in which generated water generated by a fuel cell is collected in a water tank that stores supply water to a reformer, and the generated water is circulated and used.
[0006]
[Problems to be solved by the invention]
The fuel cell does not release a gas, such as NOx, which is undesirable for the environment when acquiring energy. Therefore, from the viewpoint of environmental protection, fuel cells are rapidly spreading as an energy source for a power plant as a large plant or a vehicle replacing an internal combustion engine. In this case, in the case of a power generation plant, the so-called all-day operation is performed even in the reformer as well as the fuel cell, and the operation is stopped only at the time of maintenance and inspection of the plant. For this reason, the generated water in the fuel cell is always circulated through the circulation path and does not stay in the path. On the other hand, when the fuel cell is mounted on a vehicle or the like and used as an energy source, the fuel cell is frequently operated and stopped. For this reason, when the generated water is circulated and used even in a vehicle or the like, the generated water in the fuel cell stays in the circulation path when the fuel cell is stopped or remains stored in the water tank in the path. It becomes.
[0007]
Therefore, when the vehicle or the like moves to a cold region, or when the vehicle or the like is used in a cold region, the generated water in the route or the water tank may freeze when the operation is stopped. For this reason, there exists a possibility that a path | route may be obstruct | occluded and water cannot be sent out from a water tank. When such a situation occurs, the generated water cannot be discharged from the cathode to the outside of the fuel cell. Therefore, even if the supply of hydrogen gas and air generated by the reformer is started to cause an electrode reaction, the generated water is discharged from the cathode to the outside of the fuel cell until the blockage due to freezing is resolved. Since it cannot be released, the progress of the electrode reaction at the cathode is hindered. Therefore, the startability of the fuel cell, and hence the fuel cell system, is reduced.
[0008]
However, this decrease in startability is not unique when circulating the generated water generated in the fuel cell, but also occurs when the generated water is simply discharged outside the fuel cell. In other words, even if the generated water freezes in a path (pipe) only for this discharge, the startability is reduced for the reason described above.
[0009]
The present invention has been made to solve the above-described problems, and an object thereof is to improve the startability of a fuel cell system having a fuel cell.
[0010]
[Means for Solving the Problems]
Means employed in the fuel cell system of the present invention to achieve this object are:
A reformer for receiving a supply of a hydrocarbon compound and water and subjecting the supplied hydrocarbon compound to a reforming reaction to generate a hydrogen rich gas, and the generated hydrogen rich gas and an oxygen-containing gas as a fuel gas A fuel cell system having a fuel cell that is supplied and causes an electrode reaction,
Said Reformer Of the heater An exhaust system for guiding exhaust gas to the outside of the reformer;
A water system that guides the generated water accompanying the electrode reaction to the outside of the fuel cell,
The discharge system has a heat exchange part that performs heat exchange with the water system,
The water system includes a generated water storage unit that stores the generated water, and a first water system unit from the fuel cell to the generated water storage unit. A reforming material tank for mixing the hydrocarbon compound and water and supplying the mixture to the reformer; From the generated water storage unit Quality material tank A water circulation system having a second water system section in the above, and each of the generated water storage section, the first water system section, and the second water system section is provided so as to exchange heat with the discharge system.
Is the gist.
[0013]
In the fuel cell system of the present invention described above,
Provided in the discharge system, the reformer Of the heater Switching means for switching the exhaust gas discharge destination to either an external release system that guides the exhaust gas to the outside of the system or the heat exchange unit;
Freezing determination means for determining the possibility of water freezing in the water system;
Control means for switching control of the switching means may be provided according to the determination result.
Moreover, the said discharge system shall be directly heat-exchanged in contact with the said 1st water system part and the 2nd water system part, and shall also heat-exchange indirectly with the said produced | generated water storage part via a heat exchanger. it can.
Further, the exhaust system is in direct heat exchange with the first water system part and the second water system part,
It is also possible to surround the product water storage part in a spiral and directly exchange heat with the product water storage part.
In addition, the hydrocarbon compound supplied to the reformer together with water is methanol, and a reforming material supply path for supplying the methanol and water to the reformer is provided, and the reforming means is provided with the reformer. Dress Of the heater When the exhaust gas discharge destination is switched to the external release system, heat exchange may be performed between the external release system and the reforming material supply path.
[0014]
[Action]
In the fuel cell system of the present invention having the above-described configuration, the reformer Of the heater Since heat is exchanged with the water system by the heat exchange part of the exhaust system that guides the exhaust gas to the outside of the apparatus, the heat energy of the exhaust gas accompanying the reforming reaction that occurs when the reformer is started is given to the water system. Therefore, even if the generated water is frozen in the water system when the operation is stopped, the frozen state in the water system is quickly eliminated by the heat energy of the exhaust gas.
Moreover, since the heat energy of the exhaust gas is given to the water circulation system having the product water storage section, the first water system section, and the second water system section of the water system, the generated water is generated at any point of the water circulation system when the operation is stopped. Even if freezing occurs, water circulation is promoted at an early stage by quickly eliminating the frozen state due to the heat energy of the exhaust gas.
[0017]
Then, the possibility of freezing water in the water system is determined by the freezing determination means, and the switching means is switched by the control means according to the result, so the exhaust gas discharge destination is either the external release system or the heat exchange unit Can be switched to. Therefore, if there is a possibility of freezing the produced water, the exhaust gas is guided to the heat exchange section, and the thermal energy of the exhaust gas is used to eliminate the frozen state. If the possibility of freezing is low or low, the exhaust gas is guided to the external release system. The thermal energy of the exhaust gas can be used for other purposes.
In addition, the exhaust system is in direct heat exchange with the first water system part and the second water system part, and indirectly exchanges heat with the generated water storage part through a heat exchanger, If the product water storage part is surrounded spirally and heat exchange is performed directly with the product water storage part, the first water system part, the second water system part, and the product water storage part are generated by the thermal energy through the discharge system. Attempt to eliminate freezing.
In addition, the hydrocarbon compound supplied to the reformer together with water is methanol, and a reforming material supply path for supplying the methanol and water to the reformer is provided, and the reforming means is provided with the reformer. Dress Of the heater When the discharge destination of the exhaust gas is switched to the external release system, if heat exchange is performed between the external release system and the reforming material supply path, methanol and water in the reforming material supply path are removed. The temperature can be raised in advance.
[0018]
【Example】
In order to further clarify the configuration and operation of the present invention described above, preferred embodiments of the present invention will be described below. FIG. 1 is a block diagram illustrating a schematic configuration of a fuel cell system 10 according to an embodiment. As shown in the figure, a fuel cell system 10 includes a reforming material tank 12 that stores methanol and water, which are reforming materials, at a predetermined molar ratio, and a hydrogen-rich gas (hereinafter referred to as “hydrogen rich gas”). A reformer 20 that generates hydrogen gas) and a polymer electrolyte fuel cell (hereinafter simply referred to as a fuel cell) 40 that exhibits an electromotive force through a reaction between hydrogen and oxygen.
[0019]
The fuel cell 40 includes a solid polymer electrolyte membrane 40a sandwiched between positive and negative electrodes of an anode 40b and a cathode 40c, air from the oxygen gas supply line 42 to the cathode 40c, and a hydrogen gas supply pipe to the anode 40b. Hydrogen gas is supplied from the passage 44. The fuel cell 40 causes the electrode reactions of the above (1) and (2) to proceed with the positive and negative electrodes to generate an electromotive force, and an external drive device, for example, a motor in an electric vehicle is connected via a wiring (not shown). To drive.
[0020]
The reformer 20 includes a reformer 22 filled with a carrier carrying a catalyst for methanol reforming (for example, a Cu-Zn catalyst), and a temperature suitable for the reforming reaction of methanol. And a heater 24 for heating to (about 250 to 300 ° C.). The reformer 22 receives supply of methanol and water from the reforming material tank 12 through the reforming material supply path 15 by the pressure feed pump 14. And this reformer 22 advances the reforming reaction of methanol through the reforming catalyst to steam reform the methanol to generate hydrogen gas. The generated hydrogen gas is sent out to the hydrogen gas supply pipe 44. The heater 24 heats the reformer 22 by burning hydrogen and methanol in surplus hydrogen gas that has not been consumed in the electrode reaction at the anode 40b. The surplus hydrogen gas is supplied from the surplus gas recirculation line 26 from the fuel cell 40, and the methanol is supplied from the combustion methanol tank 28 to the heater 24 by the pressure pump 30.
[0021]
The hydrogen gas supply line 44 between the fuel cell 40 and the reformer 20 includes a CO shift unit 46 and a CO converter 48 for reducing carbon monoxide in the hydrogen gas in the line. Is provided. The CO shifter 46 reacts carbon monoxide with water to produce hydrogen and carbon dioxide to reduce carbon monoxide in the passing gas, in this case hydrogen gas. The water supply to the CO shifter 46 is performed via a pump 54 of a branch line 52 branched from a generated water circulation line 50 described later. The CO converter 48 includes a carrier carrying a catalyst (for example, a Ru catalyst or a Pt catalyst) that oxidizes to carbon dioxide in the presence of oxygen even in a minute amount of carbon monoxide, and in the passing hydrogen gas Further reduction of carbon monoxide. Note that air is introduced into the CO transformer 48 from the air introduction pipe 56, and oxygen in the air is used for the oxidation of carbon monoxide. In addition, the CO shifter 46 and the CO transformer 48 are maintained at a temperature suitable for the reaction necessary for reducing carbon monoxide.
[0022]
In addition, the fuel cell system 10 includes a generated water discharge pipe 60 for discharging generated water generated by the electrode reaction at the cathode 40 c to the outside of the fuel cell 40, a fuel cell 40 and a generated water storage tank 62 outside the fuel cell 40. Prepare between. Therefore, the produced water generated at the cathode in accordance with the electrode reaction of the fuel cell 40 is separated from the gas (excess air at the cathode) by the gas-liquid separation device 61 in the middle of the produced water discharge pipe 60 to produce the produced water. It reaches the storage tank 62 and is stored in the tank. In addition, the fuel cell system 10 includes a generated water circulation pipe 50 between the generated water storage tank 62 and the reforming material tank 12, and the generated water in the generated water storage tank 62 is supplied by a pump 64 of the pipe. Circulate through the reforming material tank 12. Therefore, this generated water is sent again to the reformer 20 and used for reforming methanol. The gas (air) separated from the generated water by the gas-liquid separator 61 is released from the release pipe 63 into the atmosphere.
[0023]
Further, the fuel cell system 10 includes an exhaust gas introduction path 70 that guides exhaust gas generated by combustion of methanol in the heater 24 and hydrogen in the surplus hydrogen gas from the reformer 20 to the outside of the device. The exhaust gas introduction path 70 is formed over the product water circulation pipe 50 and the branch pipe 52, and as shown in FIG. 2 which is a sectional view taken along line 2-2 of FIG. An exhaust gas introduction path portion 72 surrounding the exhaust gas introduction storage chamber portion 74 formed as an area including the generated water discharge pipe 60 is provided. Therefore, the exhaust gas introduction path 70, the generated water circulation pipe 50, the branch pipe 52, and the generated water discharge pipe 60 are directly heat-exchanged.
[0024]
A heat exchanger 78 is provided across the exhaust gas introduction storage chamber 74 and the generated water storage tank 62. The heat exchanger 78 includes a heat exchange part in the exhaust gas introduction storage chamber part 74 and the generated water storage tank 62, and a heat exchange medium (oil / fluid type or alcohol type coolant liquid) is provided between the two heat exchange parts. A conduit 79 is provided. Therefore, the heat exchanger 78 exchanges heat between the exhaust gas introduction storage chamber 74 and the generated water storage tank 62 of the exhaust gas introduction path 70. In addition, the exhaust gas introduction path 70 includes an exhaust gas discharge port 76 at an appropriate location separated from the reformer 20, that is, in the vicinity of the gas-liquid separator 61 in this embodiment.
[0025]
The exhaust gas introduction route 70 in the vicinity of the reformer 20 is provided with an exhaust gas branch introduction route 80 branched from the route, and a switching valve 82 for switching the exhaust gas discharge destination to either of the two routes is provided at the branch point. Is provided.
[0026]
The exhaust gas branch introduction path 80 is for guiding the exhaust gas of the reformer 20 to the outside of the system during normal operation of the fuel cell system 10, and the end of the path is an exhaust gas discharge port 84. A part of the exhaust gas branch introduction path 80 is an exhaust gas introduction path portion 86 that surrounds the reforming material supply path 15 downstream of the pumping pump 14, and in this exhaust gas introduction path portion 86, the exhaust gas branch introduction path 80. The reforming material supply path 15 is directly heat-exchanged.
[0027]
The fuel cell system 10 also includes a control device 90 configured as a logical operation circuit centered on a microcomputer. The control device 90 is installed in the generated water storage tank 62 and inputs signals from a water temperature sensor 92 for detecting the temperature of the water in the tank and other sensors and switches (not shown), and these input signals are preset. The pumping pump 14 and the switching valve 82 are driven and controlled according to the control program.
[0028]
Next, the exhaust gas discharge process of the reformer 20 performed by the fuel cell system 10 will be described based on the flowchart of FIG. The flowchart of FIG. 3 is executed following an initial process such as resetting an internal register of the CPU that is executed only when the power is turned on when an operation start switch of the fuel cell system 10, for example, an ignition switch of the vehicle is turned on. . First, when the process is started, the detected water temperature αt from the water temperature sensor 92 is read, and the value is compared with a predetermined comparison water temperature α (step S100). Since this comparison water temperature α is set in advance to a temperature (zero ° C.) at which the generated water in the generated water storage tank 62 is frozen, the generated water circulation pipe including the generated water storage tank 62 is compared by comparison in step S100. The presence or absence of freezing or the possibility of freezing in the water system of the generated water in the channel 50, the branch pipeline 52, and the generated water discharge pipeline 60 is determined.
[0029]
Here, when an affirmative determination is made, that is, when it is determined that there is freezing in the water system of the generated water or there is a possibility of this, a control signal is output to the switching valve 82 to determine the exhaust gas discharge destination of the reformer 20. Switch to the exhaust gas introduction path 70 (step S110). As a result, the exhaust gas discharged from the reformer 20 is introduced into every corner of the exhaust gas introduction path 70, and is discharged to the outside through the exhaust gas introduction storage chamber 74. Accordingly, the generated water circulation pipe 50 and the branch pipe 52 surrounded by the exhaust gas introduction path section 72 of the exhaust gas introduction path 70 and the generated water discharge pipe 60 in the exhaust gas introduction storage chamber section 74 are directly heated with the introduced exhaust gas. Exchanged. In the generated water storage tank 62, heat exchange with the exhaust gas is performed by the heat exchanger 78. Until the negative determination is made in step S100, the switching of the switching valve 82 is continued, and the exhaust gas continues to be introduced into the exhaust gas introduction path 70.
[0030]
On the other hand, if the determination in step S100 is negative, that is, if it is determined that there is no freezing in the water system of the generated water, or that freezing has been eliminated, a control signal is output to the switching valve 82 to discharge the exhaust gas. The destination is switched to the exhaust gas branch introduction path 80 (step S120). As a result, the exhaust gas is introduced into the exhaust gas branch introduction path 80 and the exhaust gas introduction path portion 86 and is discharged to the outside from the exhaust gas discharge port 84. Accordingly, heat is directly exchanged with the introduced exhaust gas in the reforming material supply path 15 surrounded by the exhaust gas introduction path portion 86. Since the switching state of the switching valve 82 is maintained as described above while the negative determination in step S100 is continued, the exhaust gas continues to be introduced into the exhaust gas branch introduction path 80.
[0031]
By the way, when the operation start switch (ignition switch or the like) of the fuel cell system 10 is turned on, the pumps 14 and 30 are driven immediately after according to a control program (not shown), and methanol is supplied to the reformer 22 of the reformer 20. Water is supplied from the reforming material tank 12, and methanol is supplied from the methanol tank 28 to the heater 24. For this reason, high-temperature exhaust gas is discharged from the reforming apparatus 20 from the beginning of operation, and the discharge destination is switched as described above.
[0032]
In the fuel cell system 10 of the embodiment described above, if the water is frozen or there is a possibility of freezing from the water temperature detected by the water temperature sensor 92 at the beginning of the operation of the system, the reformer 20 is disposed in the exhaust gas introduction path 70. The generated water discharge pipe 60 through which the generated water passes, the generated water circulation pipe 50 and the branch pipe 52 and the water system of the generated water storage tank 62 in which the generated water is stored are disposed between the exhaust gas and the exhaust gas. Heat exchange is possible. Therefore, in the fuel cell system 10 of the embodiment, even if freezing occurs in the water system of the generated water during the system stop period, the freezing is quickly eliminated by giving the heat energy of the exhaust gas to the water system. As a result, according to the fuel cell system 10 of the present embodiment, the generated water can be immediately discharged to the outside of the fuel cell 40 through the quick elimination of the blockage of the water system due to freezing, etc. The startability of the fuel cell system 10 can be improved through the smooth progress of the electrode reaction at 40c.
[0033]
Further, the generated water circulation pipe 50, the branch pipe 52, and the generated water discharge pipe 60, which are pipes through which the generated water passes, exchange heat directly with the exhaust gas through the exhaust gas introduction path section 72. Therefore, freezing can be eliminated more quickly in these pipelines.
[0034]
In addition, in the fuel cell system 10, the heat energy given to the water system such as the generated water circulation pipe 50 and the branch pipe 52 is covered with the exhaust gas from the reformer 20. Therefore, according to this fuel cell system 10, it is possible to simplify the configuration through omitting a separate heat source and improve the thermal efficiency of the system. Furthermore, the driving devices during the thawing with the exhaust gas are merely the pumps 14 and 30 and the switching valve 82. Therefore, according to the fuel cell system 10, even when the discharge of the battery proceeds during the operation stop period and the remaining amount of electricity is small, the fuel cell 40 can be surely and quickly released by driving these devices and thawing with exhaust gas. As a result, the fuel cell system 10 can be started.
[0035]
In addition, according to the fuel cell system 10, the generated water in the generated water storage tank 62 can be quickly discharged by the quick elimination of freezing in the above-described pipes such as the generated water discharge pipe 60 and the generated water storage tank 62. It can be sent to the reforming material tank 12 and reused.
[0036]
Further, in the fuel cell system 10, when freezing in the water system such as the generated water circulation pipe 50 is eliminated or freezing does not occur, in other words, the steady state of the fuel cell system 10 including the fuel cell 40. During operation, the temperature of the methanol and water in the reforming material supply path 15 is increased in advance before reaching the reformer 22 by heat exchange with the exhaust gas via the exhaust gas introduction path 86 of the exhaust gas branch introduction path 80. Therefore, according to the fuel cell system 10, the reaction efficiency in the reformer 22 and thus the operation efficiency of the system can be improved through the smooth progress of the reforming reaction of methanol in the reformer 22.
[0037]
The embodiments of the present invention have been described above. However, the present invention is not limited to these embodiments, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention.
[0038]
For example, instead of the reforming material tank 12, a methanol tank and a water tank may be used, and a configuration may be adopted in which methanol and water are supplied from each of these tanks to the reforming device 20. Even in this case, if the pipes leading from the respective tanks to the reformer 20 are warmed with exhaust gas, the methanol and water involved in the reforming reaction can be preliminarily heated to increase the efficiency of the reforming reaction. be able to.
[0039]
Further, the exhaust gas introduction path 70 may have an exhaust gas introduction spiral path that surrounds the generated water storage tank 62 in a spiral shape and directly exchanges heat with the tank. In this way, the heat exchanger 78 is not necessary, and the number of parts can be reduced and the associated costs can be reduced, and the weight can be reduced.
[0040]
Further, although the switching valve 82 is configured to be switched and controlled by the water temperature in the generated water storage tank 62 detected by the water temperature sensor 92, the present invention is not limited to this. For example, it is possible to detect the environmental temperature (atmospheric temperature) around the fuel cell system 10 and switch the switching valve 82 according to the temperature. Furthermore, a configuration is adopted in which the switching valve 82 is switched and controlled in accordance with the operation state of a manual switch operated by the driver or the like (for example, a switch that is turned on by the driver or the like when the generated water is expected to freeze). You can also.
[0041]
In addition, the comparative water temperature α when determining whether the generated water is frozen or the like need not be fixed at 0 ° C., and may be configured to be variable according to the atmospheric pressure of the environment in which the fuel cell system 10 is used. it can. Furthermore, in the fuel cell system 10, the switching valve 82 is switched and controlled in accordance with the comparison result with the comparative water temperature α to switch the exhaust gas discharge destination. However, the exhaust gas is continuously introduced only into the exhaust gas introduction path 70 from the start. Thus, it is possible to adopt a configuration in which heat exchange with the exhaust gas is always performed only for the water system of the generated water such as the generated water circulation pipe 50, the branch pipe 52, and the generated water storage tank 62.
[0042]
【The invention's effect】
As described above, in the fuel cell system of the present invention, even when the generated water freezes in the water system that leads the generated water accompanying the electrode reaction to the outside of the fuel cell, the freezing can be quickly performed by applying thermal energy to the water system. Cancel the condition. As a result, according to the fuel cell system of the present invention, the generated water can be immediately discharged to the outside of the fuel cell through the rapid elimination of the blockage of the water system pipeline due to freezing, etc. The startability of the fuel cell system can be improved through the smooth progress of the reaction.
Moreover, in the fuel cell system of the present invention, the heat energy applied to the water system is reformed. Heater exhaust Since it is covered with gas, it is possible to simplify the configuration through omitting a separate heat source and improve the thermal efficiency of the system.
Furthermore, since the heat energy of the exhaust gas is given to the water circulation system having the product water storage section, the first water system section, and the second water system section of the water system, it is generated at any point in the water circulation system when the operation is stopped. Even if the water freezes, the water circulation can be secured at an early stage by quickly eliminating the frozen state of the water circulation system of the produced water due to freezing, and the produced water can be reused at an early stage.
[0045]
In addition, the exhaust gas discharge destination is switched depending on whether the water system is frozen or not, and the heat energy supply destination of the exhaust gas is changed to either the water system of the generated water or an external release system that leads the exhaust gas to the outside of the system. Therefore, not only can the startability of the fuel cell system be improved through the rapid elimination of the frozen state, but also the thermal energy can be effectively used in the external release system.
In addition, direct heat exchange between the discharge system and the first water system part and the second water system part , Discharge system Indirect heat exchange between the main and the product water storage part through a heat exchanger, or the product water storage part is spirally surrounded Exhaust system Freezing in the first water system part, the second water system part, and the generated water storage part can be achieved by direct heat exchange of the generated water storage part by the series. In particular , Discharge system If the product water storage part is surrounded in a spiral shape, a heat exchanger becomes unnecessary, and the number of parts and the associated cost can be reduced, and the weight can be reduced.
In addition, the hydrocarbon compound supplied to the reformer together with water is methanol, and a reforming material supply path for supplying the methanol and water to the reformer is provided. Of the heater When the exhaust gas discharge destination is switched to the external release system, heat is exchanged between the external release system and the reforming material supply path, so the methanol and water in the reforming material supply path are preheated. it can. And, in the reformer supplied with the heated methanol and water, the reforming reaction of methanol can proceed smoothly, and thereby the reaction efficiency in the reformer, and eventually the system Operation efficiency can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a fuel cell system 10 according to an embodiment.
2 is a sectional view taken along line 2-2 of FIG.
FIG. 3 is a flowchart showing an exhaust gas discharge process of the reformer 20 performed by the fuel cell system 10;
[Explanation of symbols]
10. Fuel cell system
12 ... Reformed material tank
14, 30 ... Pressure feed pump
15 ... reforming material supply path
20 ... reformer
22 ... reformer
24 ... Heater
26 ... Excess gas reflux line
28 ... Methanol tank
40 ... Fuel cell
40a ... Solid polymer electrolyte membrane
40b ... Anode
40c ... cathode
42. Oxygen gas supply line
44 ... Hydrogen gas supply line
46 ... CO shifter
48 ... CO transformer
50 ... Generated water circulation pipeline
52 ... Branch pipeline
54 ... Pump
56 ... Air introduction pipe
60 ... Generated water discharge pipe
61 ... Gas-liquid separator
62 ... Generated water storage tank
63 ... Release tube
64 ... Pump
70 ... Exhaust gas introduction route
72. Exhaust gas introduction path section
74 ... exhaust gas introduction storage chamber
76 ... Exhaust gas outlet
78 ... Heat exchanger
79 ... Conduit
80 ... Exhaust gas branch introduction route
82 ... Switching valve
84 ... Exhaust gas outlet
86 ... Exhaust gas introduction path
90 ... Control device
92 ... Water temperature sensor

Claims

A reformer for receiving a supply of a hydrocarbon compound and water and subjecting the supplied hydrocarbon compound to a reforming reaction to generate a hydrogen rich gas, and the generated hydrogen rich gas and an oxygen-containing gas as a fuel gas A fuel cell system having a fuel cell that is supplied and causes an electrode reaction,
A discharge line which leads to the heater of the exhaust gas which the reforming equipment has outside reforming apparatus,
A water system that guides the generated water accompanying the electrode reaction to the outside of the fuel cell,
The discharge system has a heat exchange part that performs heat exchange with the water system,
The reformer is configured by mixing a generated water storage unit for storing the generated water, a first water system unit from the fuel cell to the generated water storage unit , the hydrocarbon compound and water. reforming a material tank, a water circulation system and a second water line section from the product water reservoir until the modifying material tank unit, the product water reservoir, the first water system for supplying the And a second water system section so as to exchange heat with the discharge system.

The fuel cell system according to claim 1, wherein
Furthermore,
Provided in the exhaust system, and switching means for switching the discharge destination of the exhaust gas heater in which the reforming equipment has, in any one of the heat exchanging portion and the external release system that guides the exhaust gas to the outside of the system,
Freezing determination means for determining the possibility of water freezing in the water system;
A fuel cell system comprising control means for switching the switching means according to the determination result.

The fuel cell system according to claim 1, wherein
The discharge system is
Direct heat exchange in contact with the first water system part and the second water system part,
A fuel cell system for indirectly exchanging heat with the generated water reservoir through a heat exchanger.

The fuel cell system according to claim 1, wherein
The discharge system is
In direct contact with the first water system part and the second water system part to exchange heat,
A fuel cell system that surrounds the generated water storage section in a spiral shape and directly exchanges heat with the generated water storage section.

The fuel cell system according to claim 2, wherein
A hydrocarbon compound supplied to the reformer together with water is methanol, and includes a reforming material supply path for supplying the methanol and water to the reformer,
When the discharge destination of the exhaust gas of the heater included in the modified equipment by the switching means is switched to said external release system, fuel cell heat exchange between the external release system and the modifying material supply path system.