JP5207230B2 - System for carrying out performance recovery method of polymer electrolyte fuel cell - Google Patents

System for carrying out performance recovery method of polymer electrolyte fuel cell Download PDF

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JP5207230B2
JP5207230B2 JP2007296482A JP2007296482A JP5207230B2 JP 5207230 B2 JP5207230 B2 JP 5207230B2 JP 2007296482 A JP2007296482 A JP 2007296482A JP 2007296482 A JP2007296482 A JP 2007296482A JP 5207230 B2 JP5207230 B2 JP 5207230B2
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pure water
polymer electrolyte
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JP2009123534A (en
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敦史 加藤
哲也 吉田
勉 五百蔵
伊藤　　博
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Takasago Thermal Engineering Co Ltd
National Institute of Advanced Industrial Science and Technology AIST
Daiki Ataka Engineering Co Ltd
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National Institute of Advanced Industrial Science and Technology AIST
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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本発明は、固体高分子形燃料電池の性能回復方法を実施するためのシステムに関するものである。 The present invention relates to a system for carrying out a performance recovery method for a polymer electrolyte fuel cell.

固体高分子形燃料電池は、長期的な運転により供給ガスや加湿水に含まれる不純物や、電池システムを構成する各基材から溶出する無機・有機成分が汚染物質として電池内部に蓄積していく。その結果反応場の減少が発生し、電池の性能が低下していく。   In polymer electrolyte fuel cells, impurities contained in supply gas and humidified water and inorganic and organic components eluted from each base material constituting the battery system accumulate in the battery as pollutants during long-term operation. . As a result, the reaction field decreases, and the performance of the battery decreases.

より詳述すると、固体高分子形燃料電池の性能を低下させる内部抵抗（過電圧）には、抵抗過電圧、活性化過電圧、拡散過電圧があるが、長期的な運転により、電池内部の膜電極接合体へ前記汚染物質が蓄積したり、基材の濡れに伴うガス拡散性の低下により、これらの過電圧が徐々に上昇し、燃料電池の性能が低下する。   More specifically, the internal resistance (overvoltage) that lowers the performance of the polymer electrolyte fuel cell includes a resistance overvoltage, an activation overvoltage, and a diffusion overvoltage. Due to the accumulation of the pollutants and the decrease in gas diffusibility associated with the wetting of the base material, these overvoltages gradually increase and the performance of the fuel cell deteriorates.

このような固体高分子形燃料電池の性能低下を回復させる技術として、燃料電池運転時の酸化剤極側に、直接あるいは膜電極接合体を介して燃料を供給し、その後元の燃料電池運転時とは逆方向に電流が流れるように燃料電池運転をしたり、燃料極側に燃料を導入して、酸化剤極から燃料極へ外部電源から電流を流すようにして燃料電池性能を回復する方法が提案されている（特許文献１〜３）。   As a technique for recovering the performance degradation of such a polymer electrolyte fuel cell, the fuel is supplied to the oxidant electrode side during the fuel cell operation directly or via the membrane electrode assembly, and then the original fuel cell operation is performed. To restore the fuel cell performance by operating the fuel cell so that the current flows in the opposite direction, or by introducing the fuel to the fuel electrode side and flowing the current from the external power source from the oxidizer electrode to the fuel electrode Has been proposed (Patent Documents 1 to 3).

特開２００１−８５０３７号公報JP 2001-85037 A 特開２００３−２７２６８６号公報JP 2003-272686 A 特開２００５−１６６４７９号公報JP 2005-166479 A

しかしながら燃料である水素と酸化剤である酸素が混合した状態で電極触媒に接触すると、触媒上で激しい反応が起こる。これによって発電効率の低下を招くばかりでなく、水素、酸素の濃度によっては膜の破損が発生し、それが本来果たすべき燃料極と酸化剤極のシール性を失うため、電池の破損につながる危険がある。このため燃料と酸化剤が混合する可能性を完全に排除する必要がある。また特許文献１、２の方法では、燃料電池に対して外部から加える電流値や、供給する水素流量等、複数のパラメータを厳密に監視する必要があり、制御も複雑なものとなってしまうという問題があった。   However, when the electrode catalyst is brought into contact with hydrogen as a fuel and oxygen as an oxidant, a vigorous reaction occurs on the catalyst. This not only reduces power generation efficiency, but also damages the membrane depending on the concentration of hydrogen and oxygen, which can lead to damage to the battery because it loses the seal between the fuel electrode and oxidant electrode that should be fulfilled. There is. For this reason, it is necessary to completely eliminate the possibility of mixing fuel and oxidant. Further, in the methods of Patent Documents 1 and 2, it is necessary to strictly monitor a plurality of parameters such as a current value applied to the fuel cell from the outside and a hydrogen flow rate to be supplied, and the control becomes complicated. There was a problem.

本発明はかかる点に鑑みてなされたものであり、酸化剤極への燃料導入や各種の厳密な制御を行なうことなく、安全にかつ簡単、確実に燃料電池性能の回復を実現することを目的としている。   The present invention has been made in view of the above points, and an object of the present invention is to safely, easily, and reliably recover the fuel cell performance without introducing fuel into the oxidizer electrode and performing various strict controls. It is said.

上記目的を達成するため、本発明は、固体高分子形燃料電池における、燃料電池運転時の酸化剤極側及び燃料電池運転時の燃料極側の双方に対して、導電率が１μＳ／ｃｍ以下、ＴＯＣが１ｐｐｍ以下である純水を供給するとともに、前記固体高分子形燃料電池の集電体に対して、燃料電池運転時とは逆方向の電流を流すように外部電源から電力を供給して前記純水を電気分解させる水電解運転を行なって、固体高分子形燃料電池の性能を回復させる方法を実施するためのシステムであって、
前記固体高分子形燃料電池内の燃料極側に通じ、水電解運転時に生成した水素の排出経路及び燃料電池運転時には燃料の供給経路となる配管１、燃料電池運転時の燃料排出経路となる配管３と、
前記固体高分子形燃料電池内の酸化剤極側に通じ、水電解運転時に生成した酸素の排出経路及び燃料電池運転時には酸素の供給経路となる配管２と、燃料電池運転時の酸化剤排出経路となる配管４とを有し、
前記配管１には、純水を貯蔵するとともに、気液分離機能を有するタンク１１が設けられ、タンク１１の上部には、バルブＶ１１を介してガス貯蔵タンク１７が設けられ、タンク１１の下部には、配管３にタンク１１内の純水を供給する配管４１が接続され、
前記配管２には、純水を貯蔵するとともに、気液分離機能を有するタンク１２が設けられ、タンク１２の上部には、バルブＶ１３を介してガス貯蔵タンク１８、が設けられ、タンク１２の下部には、配管４にタンク１２内の純水を供給する配管７が接続され、
水電解運転時には、タンク１１内の純水を配管４１を介して配管３に流し、タンク１２内の純水を配管７を介して配管４に流し、
水電解運転時に生成して配管１から出た水素は、タンク１１において気液分離した後ガス貯蔵タンク１７に貯蔵し、配管２から出た酸素は、タンク１２において気液分離した後ガス貯蔵タンク１８に貯蔵して、これら貯蔵した水素及び酸素を、燃料電池運転時の燃料及び酸化剤として用いるようにし、
燃料電池運転時には、ガス貯蔵タンク１７に貯蔵されている水素を、配管１７ｂ、配管１からタンク１１へ送って当該タンク１１で加湿して前記固体高分子形燃料電池に供給するとともに、ガス貯蔵タンク１８に貯蔵されている酸素を、配管１８ｂからタンク１２へ送って当該タンク１２で加湿して前記固体高分子形燃料電池に供給するように構成されたことを特徴としている。なお上記した構成の符号は、本願の添付図面図２、図５を参照されたい。 To achieve the above object, the present invention provides a polymer electrolyte fuel cell having a conductivity of 1 μS / cm or less for both the oxidant electrode side during fuel cell operation and the fuel electrode side during fuel cell operation. In addition to supplying pure water with a TOC of 1 ppm or less, power is supplied from an external power supply to the current collector of the polymer electrolyte fuel cell so that a current in the direction opposite to that during fuel cell operation flows. the pure water is row water electrolysis operation for electrolysis, a system for implementing the method of restoring the performance of the polymer electrolyte fuel cell Te,
A pipe 1 that leads to the fuel electrode side in the polymer electrolyte fuel cell and serves as a discharge path for hydrogen generated during water electrolysis operation, a fuel supply path during fuel cell operation, and a fuel discharge path during fuel cell operation 3 and
A pipe 2 that leads to the oxidant electrode side in the polymer electrolyte fuel cell and serves as a discharge path for oxygen generated during water electrolysis operation and a supply path for oxygen during fuel cell operation, and an oxidant discharge path during fuel cell operation And piping 4 to be
The pipe 1 is provided with a tank 11 for storing pure water and having a gas-liquid separation function. A gas storage tank 17 is provided above the tank 11 via a valve V11. Is connected to a pipe 41 for supplying pure water in the tank 11 to the pipe 3;
The pipe 2 is provided with a tank 12 that stores pure water and has a gas-liquid separation function. A gas storage tank 18 is provided above the tank 12 via a valve V13. Is connected to a pipe 7 for supplying pure water in the tank 12 to the pipe 4.
At the time of water electrolysis operation, pure water in the tank 11 is caused to flow to the pipe 3 via the pipe 41, and pure water in the tank 12 is caused to flow to the pipe 4 via the pipe 7,
Hydrogen generated during the water electrolysis operation and discharged from the pipe 1 is gas-liquid separated in the tank 11 and then stored in the gas storage tank 17, and oxygen discharged from the pipe 2 is gas-liquid separated in the tank 12 and then stored in the gas storage tank 17. 18 and use these stored hydrogen and oxygen as fuel and oxidant during fuel cell operation,
During operation of the fuel cell, the hydrogen stored in the gas storage tank 17 is sent from the pipe 17b and the pipe 1 to the tank 11, humidified in the tank 11, and supplied to the polymer electrolyte fuel cell. The oxygen stored in 18 is sent from the pipe 18b to the tank 12, humidified in the tank 12, and supplied to the polymer electrolyte fuel cell . For the reference numerals of the above-described configurations, refer to FIGS. 2 and 5 attached hereto.

本発明において、水電解運転においては、燃料電池運転時の酸化剤極側に純水を供給し、外部から電気を加えることにより行う。このとき燃料電池運転時の酸化剤極側の電極界面では、次の式に示す化学反応が起こる。
２Ｈ２Ｏ→Ｏ２＋４Ｈ＋＋４ｅ− In the present invention, the water electrolysis operation is performed by supplying pure water to the oxidant electrode side during fuel cell operation and applying electricity from the outside. At this time, a chemical reaction represented by the following formula occurs at the electrode interface on the oxidant electrode side during fuel cell operation.
2H 2 O → O 2 + 4H + + 4e−

前記式からわかるように、水電解運転では燃料電池運転時の酸化剤極側での電極界面で水素が発生することはない。したがって燃料と酸化剤が混合する可能性は全くない。なおこの反応で発生した水素イオン（プロトン）は、反応の時点で電解質膜内に取り込まれ、燃料電池運転時の燃料極側（水素側）に向かって移動していき、燃料電池運転時の燃料極側（水素側）の電極界面で外部電源から供給される電子と結合してはじめて水素分子となる。   As can be seen from the above equation, in the water electrolysis operation, hydrogen is not generated at the electrode interface on the oxidant electrode side during the fuel cell operation. Therefore, there is no possibility of mixing fuel and oxidant. The hydrogen ions (protons) generated by this reaction are taken into the electrolyte membrane at the time of the reaction and move toward the fuel electrode side (hydrogen side) during fuel cell operation, and the fuel during fuel cell operation Hydrogen molecules are not formed until they are combined with electrons supplied from an external power source at the electrode interface on the pole side (hydrogen side).

ここで膜内のプロトンの輸送現象を簡略的に示すと図１のようになる。プロトンは数個の水分子を随伴しながら、スルホン酸基を伝って膜内を移動する。そのためスルホン酸基が他のイオン（ここでいう不純物）に置換されると、イオン交換基として機能しなくなるため、水素イオンの伝導性が低下し、結果的に出力電圧が低下する。置換された不純物は水素イオンよりも結合力が強いため、通常の運転では排除できないが、膜内を移動するプロトンの量を数倍に増やし、さらにプロトンの流れ方向を反対にすることでも排除されやすくなる。   Here, the proton transport phenomenon in the membrane is simply shown in FIG. The proton moves through the membrane through the sulfonic acid group while accompanying several water molecules. For this reason, when the sulfonic acid group is substituted with other ions (impurities here), the ion does not function as an ion exchange group, so that the conductivity of hydrogen ions is lowered, and as a result, the output voltage is lowered. The substituted impurities are stronger than hydrogen ions and cannot be eliminated in normal operation, but they can also be eliminated by increasing the amount of protons moving through the membrane several times and reversing the proton flow direction. It becomes easy.

一般的に燃料電池運転では、電流密度の上昇に伴いガスの拡散性に起因する拡散過電圧が発生する。この状態からさらに電流密度を上昇させると、電圧の急低下が起こり、運転自体が不可能となる。   In general, in a fuel cell operation, a diffusion overvoltage caused by gas diffusibility is generated with an increase in current density. If the current density is further increased from this state, the voltage suddenly drops, and the operation itself becomes impossible.

それに比べて水電解運転では、一般的に燃料電池運転時の数倍に相当する数Ａ／ｃｍ２の電流密度においても上記の問題を起こすことはなく、安定的な運転が可能である。つまり本発明では、燃料電池運転時とは逆方向の電流を、一般的な燃料運転時の数倍、また従来の技術と比べても数１０倍程度の電流を流す事が可能である。これにより、プロトンが膜電極接合体を移動するときの汚染物資の排出、すなわち膜内から膜外への移動が促進され、燃料電池性能を回復させることができる。 In contrast, in the water electrolysis operation, the above problem is not caused even at a current density of several A / cm 2 , which is generally several times that during fuel cell operation, and stable operation is possible. In other words, in the present invention, it is possible to pass a current in the direction opposite to that during fuel cell operation, several times that during general fuel operation, and several tens times as much as that in the conventional technology. Thereby, discharge of contaminants when protons move through the membrane electrode assembly, that is, movement from the inside of the membrane to the outside of the membrane is promoted, and the fuel cell performance can be recovered.

また本発明では、燃料電池運転時の酸化剤極側に対して純水を供給する際には、燃料電池運転時の燃料極側に対しても純水を供給するようにしているので、固体高分子形燃料電池の膜内から排出された不純物をセル外まで確実に排出することができ、また水電解運転時の安全性も高まる。 In the present invention, when supplying pure water with respect to the oxidant electrode side during the fuel cell operation, since so as to supply the pure water with respect to the fuel electrode side during the fuel cell operation, solid Impurities discharged from inside the membrane of the polymer fuel cell can be reliably discharged to the outside of the cell, and safety during water electrolysis operation is also increased.

また電気分解に供する純水は、導電率が１μＳ／ｃｍ以下、ＴＯＣ（Ｔｏｔａｌ Ｏｒｇａｎｉｃ Ｃａｒｂｏｎ：総有機炭素）が１ｐｐｍ以下である純水を 用いているから、濃度平衡（濃度差があると同一濃度になろうとして物質移動が発生）によって、膜内の不純物イオンが純水中のプロトンと置換されるので、このような高純度の純水を供給すること自体にも膜の洗浄効果がある。 The pure water to be subjected to electrolysis, conductivity 1 [mu] S / cm or less, TOC: same concentration when from (Total Organic Carbon total organic carbon) is used pure water is 1ppm or less, there is a concentration equilibrium (density difference Since the impurity ions in the membrane are replaced by protons in the pure water due to the occurrence of mass transfer), the supply of such high purity pure water itself also has a membrane cleaning effect.

ところで膜内の不純物を効率的に排出するためには、不純物が膜表面近傍にある時点で性能回復運転を行うのが理想的である。これは不純物の移動行程が短ければ短いほど、膜外への排出が容易となるからである。しかしながら、不純物が膜表面近傍に存在しているかどうかは直接的には測定しがたい。この点に関し、発明者らの知見によれば評価指標となるのは電圧値であり、さらに発明者らが調べた結果、初期電圧に対して２０ｍＶ低下した時点で回復運転を行うことが理想的であると考えられる。   By the way, in order to efficiently discharge impurities in the film, it is ideal to perform performance recovery operation when the impurities are in the vicinity of the film surface. This is because the shorter the migration process of impurities, the easier the discharge out of the film. However, it is difficult to directly measure whether impurities are present near the film surface. In this regard, according to the inventors' knowledge, the evaluation index is the voltage value. Further, as a result of investigations by the inventors, it is ideal to perform the recovery operation when the voltage drops by 20 mV with respect to the initial voltage. It is thought that.

そこで実際の回復方法の実施にあたっては、たとえば固体高分子形燃料電池の運転中の電圧値を監視し、初期の電圧値に対して２０ｍＶ以上の電圧低下を検知した時点で固体高分子形燃料電池の運転を停止し、その後前記した本発明の固体高分子形燃料電池の性能回復方法を実施することが提案できる。 Therefore, in carrying out the actual recovery method , for example, the voltage value during operation of the polymer electrolyte fuel cell is monitored, and when a voltage drop of 20 mV or more is detected with respect to the initial voltage value, the polymer electrolyte fuel cell is detected. It can be proposed that the operation of the solid polymer fuel cell according to the present invention is performed after the operation is stopped.

本発明によれば、酸化剤極への燃料導入や各種の厳密な制御を行なうことなく、安全にかつ簡単、確実に燃料電池性能の回復を実現することができる。   According to the present invention, fuel cell performance can be safely, easily and reliably recovered without introducing fuel into the oxidizer electrode and performing various strict controls.

図２に実施の形態にかかるシステムの基本的な構成を示す。燃料電池ＦＣに対して、配管１、２、３、４が接続されている。配管１は、水電解運転時に生成した水素の排出経路として機能し、配管２は水電解運転時に生成した酸素の排出経路として機能する。また配管３は、燃料電池運転時の燃料排出経路として機能し、配管４は燃料電池運転時の酸化剤排出経路として機能するものである。また配管４は、燃料電池ＦＣの水電解運転時には、純水供給経路として使用される。   FIG. 2 shows a basic configuration of a system according to the embodiment. Pipes 1, 2, 3, and 4 are connected to the fuel cell FC. The pipe 1 functions as a discharge path for hydrogen generated during the water electrolysis operation, and the pipe 2 functions as a discharge path for oxygen generated during the water electrolysis operation. The pipe 3 functions as a fuel discharge path during fuel cell operation, and the pipe 4 functions as an oxidant discharge path during fuel cell operation. The pipe 4 is used as a pure water supply path during the water electrolysis operation of the fuel cell FC.

燃料電池ＦＣに対しては、さらに電池内部のパージや乾燥を行なう、不活性ガス供給経路となる、配管５、６が接続されている。   The fuel cell FC is connected with pipes 5 and 6 that serve as an inert gas supply path for purging and drying the inside of the battery.

配管１には、タンク１１が設けられ、配管２には、タンク１２が設けられている。これらタンク１１、１２は純水を貯蔵しており、燃料電池運転時の加湿タンクとして機能し、また水電解運転時には、純水貯蔵タンクとして機能するものである。すなわち水電解運転時には、タンク１２に貯蔵されている純水が、ポンプ１３を介して配管７から配管４を経由して燃料電池ＦＣの酸化剤極側に供給される。   The pipe 1 is provided with a tank 11, and the pipe 2 is provided with a tank 12. These tanks 11 and 12 store pure water and function as humidification tanks during fuel cell operation, and also function as pure water storage tanks during water electrolysis operation. That is, during the water electrolysis operation, pure water stored in the tank 12 is supplied from the pipe 7 to the oxidant electrode side of the fuel cell FC via the pipe 7 via the pump 13.

配管５、６、７、４には、各々対応するバルブＶ１〜Ｖ４が設けられている。これらＶ１〜Ｖ４は、制御装置１４によって開閉制御されている。   Corresponding valves V1 to V4 are provided in the pipes 5, 6, 7, and 4, respectively. These V1 to V4 are controlled to be opened and closed by the control device 14.

また水電解運転時には、外部電源１５から燃料電池ＦＣに対して電流を供給して、水の電気分解が行われるようになっている。より詳述すれば、後述の集電体２５、２６に対して、燃料電池運転時とは逆向きの電流が流れるように、電流が供給される。なお燃料電池ＦＣの乾燥状態は、抵抗計１６によって計測される抵抗値によって測定される。外部電源１５、抵抗計１６も制御装置１４によって制御される。   Further, during the water electrolysis operation, an electric current is supplied from the external power source 15 to the fuel cell FC so that the water is electrolyzed. More specifically, a current is supplied to current collectors 25 and 26, which will be described later, so that a current in a direction opposite to that during fuel cell operation flows. The dry state of the fuel cell FC is measured by the resistance value measured by the resistance meter 16. The external power supply 15 and the resistance meter 16 are also controlled by the control device 14.

タンク１１には、タンク１１の上部に接続された配管１７ａ、１７ｂを介してガス貯蔵タンク１７が設けられ、タンク１２には、タンク１２の上部に接続された配管１８ａ、１８ｂを介してガス貯蔵タンク１８が設けられている。これらガス貯蔵タンク１７、１８は後述の性能回復運転である水電解運転時に発生する水素、酸素を貯蔵するものである。なお各配管１７ａ、１７ｂ、１８ａ、１８ｂには、各々対応するバルブＶ１１、Ｖ１２、Ｖ１３、Ｖ１４が設けられている。   The tank 11 is provided with a gas storage tank 17 through pipes 17 a and 17 b connected to the upper part of the tank 11, and the tank 12 has a gas storage through pipes 18 a and 18 b connected to the upper part of the tank 12. A tank 18 is provided. These gas storage tanks 17 and 18 store hydrogen and oxygen generated during water electrolysis operation, which is a performance recovery operation described later. The pipes 17a, 17b, 18a, 18b are provided with corresponding valves V11, V12, V13, V14, respectively.

図３に、固体高分子形の燃料電池ＦＣの内部断面形状を示した。この燃料電池ＦＣは、一般的な固体高分子形燃料電池と同様の構成を有している。すなわち、反応を担うプロトン伝導性固体高分子膜２１と、このプロトン伝導性固体高分子膜２１の両面に接合された電極部となる白金電極の触媒２２、２３とによって膜電極接合体２４が構成されている。膜電極接合体２４の両面には、電子の授受とガス拡散を担う集電体２５、２６が配置されており、さらに内部に反応流体の流路２７ａ、２８ａを形成するセパレータ２７、２８が集電体２５、２６の両面に配置されている。以上の構成で、最小単位のセル（単セル）が構成される。   FIG. 3 shows the internal cross-sectional shape of the solid polymer fuel cell FC. The fuel cell FC has the same configuration as a general polymer electrolyte fuel cell. That is, the membrane electrode assembly 24 is constituted by the proton conductive solid polymer membrane 21 responsible for the reaction and the platinum electrode catalysts 22, 23 serving as electrode portions joined to both surfaces of the proton conductive solid polymer membrane 21. Has been. On both sides of the membrane electrode assembly 24, current collectors 25, 26 responsible for electron exchange and gas diffusion are arranged, and separators 27, 28 that form reaction fluid flow paths 27 a, 28 a are collected inside. The electric bodies 25 and 26 are disposed on both surfaces. With the above configuration, the smallest unit cell (single cell) is configured.

なおセパレータ２７、２８には電圧を測定するための電圧測定用の端子２９、３０が取付けられている。   The separators 27 and 28 are provided with voltage measuring terminals 29 and 30 for measuring the voltage.

かかる構成を有する燃料電池ＦＣに水電解の機能を具備させるには、燃料電池時の酸化剤極側の基材を水電解の運転状態に耐えられる仕様に変更する必要がある。その一例としては、たとえば特開２００４−１３４１３４号公報や、特開２００７−１２３１５号公報に開示されているように、白金電極の触媒２３に少量のイリジウム（黒）を混入し、基材の撥水性を調整し、集電体２６とセパレータ２７、２８を、Ｐｔでメッキする方法がある。なお、その他の構造については特段変更する必要はない。   In order for the fuel cell FC having such a configuration to have a water electrolysis function, it is necessary to change the base on the oxidizer electrode side in the fuel cell to a specification that can withstand the operation state of water electrolysis. For example, as disclosed in Japanese Patent Application Laid-Open No. 2004-134134 and Japanese Patent Application Laid-Open No. 2007-12315, for example, a small amount of iridium (black) is mixed in the catalyst 23 of the platinum electrode, so There is a method in which the aqueous solution is adjusted and the current collector 26 and the separators 27 and 28 are plated with Pt. There is no need to change any other structure.

燃料電池ＦＣは以上の構成を有しており、次のその運転例について説明する。
燃料電池運転時は、バルブＶ１〜バルブＶ３は閉鎖、バルブＶ４は開放し、図４に示したように、配管１へ燃料を、配管２へ酸化剤を導入し、タンク１１、１２で加湿を行った後に燃料電池ＦＣに供給する。そうすると、集電体２５、２６間で電位差が生じるため、負荷３１を接続することで発電ができる。 The fuel cell FC has the above configuration, and the following operation example will be described.
During the fuel cell operation, the valves V1 to V3 are closed and the valve V4 is opened. As shown in FIG. 4, fuel is introduced into the pipe 1 and oxidant is introduced into the pipe 2, and the tanks 11 and 12 are humidified. After the operation, the fuel cell FC is supplied. Then, since a potential difference is generated between the current collectors 25 and 26, power generation can be performed by connecting the load 31.

このとき燃料電池ＦＣでは外部の負荷３１に応じた量のガスが消費され、反応に使われなかったガスは配管３、４を介して系外に排出される。なお、消費されなかったガスは別途ルートを設けて再循環させてもよい。たとえば、ガス貯蔵タンク１７、１８に回収してもよい。   At this time, an amount of gas corresponding to the external load 31 is consumed in the fuel cell FC, and the gas not used in the reaction is discharged out of the system via the pipes 3 and 4. The gas that has not been consumed may be recirculated by providing a separate route. For example, the gas may be collected in the gas storage tanks 17 and 18.

次に性能回復運転である水電解運転時について説明する。水電解運転時においては、まずバルブＶ１、Ｖ２は閉鎖し、バルブＶ３は開放、バルブＶ４は閉鎖する。そしてタンク１２に貯蔵した純水をポンプ１３で吸込み、配管４を通じて燃料電池ＦＣにおける燃料電池運転時の酸化剤極側、すなわち流路２８ａの集電体２６側に純水を供給する。なおこのとき供給する純水の流量は、電気分解される水の１００倍以上の量が好ましい。そして外部電源１５の陰極を集電体２５に、陽極を集電体２６に接続して、集電体２５、２６に対して電流を供給する。   Next, the water electrolysis operation that is the performance recovery operation will be described. During the water electrolysis operation, the valves V1 and V2 are first closed, the valve V3 is opened, and the valve V4 is closed. The pure water stored in the tank 12 is sucked by the pump 13 and supplied through the pipe 4 to the oxidant electrode side during the fuel cell operation in the fuel cell FC, that is, to the current collector 26 side of the flow path 28a. The flow rate of pure water supplied at this time is preferably 100 times or more of the electrolyzed water. Then, the cathode of the external power supply 15 is connected to the current collector 25 and the anode is connected to the current collector 26 to supply current to the current collectors 25 and 26.

そうすると、燃料電池ＦＣでは外部電源１５から与える電流に応じた量のガスである水素、酸素が発生する。発生した水素は配管１を通じて排出され、一旦タンク１１に導入され、そこで気液分離を行った後に系外に排出される。一方、発生した酸素は配管２を通じて排出され、タンク１２に導入され、そこで気液分離を行った後に系外に排出される。   Then, in the fuel cell FC, hydrogen and oxygen, which are gases corresponding to the current supplied from the external power source 15, are generated. The generated hydrogen is discharged through the pipe 1 and once introduced into the tank 11, where after gas-liquid separation is performed, the hydrogen is discharged out of the system. On the other hand, the generated oxygen is discharged through the pipe 2 and introduced into the tank 12, where after gas-liquid separation is performed, it is discharged out of the system.

なおこれら生成したガスは、ガス貯蔵タンク１７、１８に各々貯蔵される。すなわち、水電解運転時には、バルブＶ１１、Ｖ１３は開放、バルブＶ１２、Ｖ１４は閉鎖しておく。これによって、水電解運転時に発生した水素は、タンク１１、配管１７ａを経て、ガス貯蔵タンク１７に貯蔵され、水電解運転時に発生した酸素は、タンク１２、配管１８ａを経て、ガス貯蔵タンク１８に貯蔵される。このようにしておくことで、次の燃料電池運転時の燃料、酸化剤として、これら再利用することができる。   These generated gases are stored in gas storage tanks 17 and 18, respectively. That is, during the water electrolysis operation, the valves V11 and V13 are opened and the valves V12 and V14 are closed. Thus, hydrogen generated during the water electrolysis operation is stored in the gas storage tank 17 via the tank 11 and the pipe 17a, and oxygen generated during the water electrolysis operation is stored in the gas storage tank 18 via the tank 12 and the pipe 18a. Stored. By doing in this way, these can be reused as fuel and oxidant during the next fuel cell operation.

なお水電解運転時で発生した水素、酸素を貯蔵する場合には、燃料電池運転時の運転圧力に対して、５０ｋＰａ以上の圧力で貯蔵することが好ましい。ただし、水電解運転時は、発明者らの知見では１ＭＰａで運転することができるので、そのような高圧で貯蔵する際に、格別昇圧機は不要である。   In addition, when storing hydrogen and oxygen generated during the water electrolysis operation, it is preferable to store at a pressure of 50 kPa or more with respect to the operation pressure during the fuel cell operation. However, since the inventors can operate at 1 MPa during water electrolysis operation, a special booster is not necessary when storing at such a high pressure.

そして燃料電池運転時の際には、バルブＶ１１、Ｖ１３は閉鎖、バルブＶ１２、Ｖ１４は開放して、各々ガス貯蔵タンク１７からは水素を配管１７ｂ、配管１を通じて燃料電池ＦＣに供給し、ガス貯蔵タンク１８からは酸化剤としての酸素を各々配管１８ｂ、配管２を通じて各々燃料電池ＦＣに供給することになるが、この場合、燃料電池ＦＣで必要なガス量に応じて、バルブＶ１２、Ｖ１４の開度を制御する。たとえば燃料電池ＦＣの出口圧力、すなわち配管３、４での圧力が一定の圧力となるように、これらバルブＶ１２、Ｖ１４の開度を調整することが提案できる。   When the fuel cell is operated, the valves V11 and V13 are closed and the valves V12 and V14 are opened, and hydrogen is supplied from the gas storage tank 17 to the fuel cell FC through the pipe 17b and the pipe 1, respectively. Oxygen as an oxidant is supplied from the tank 18 to the fuel cell FC through the pipe 18b and the pipe 2, respectively. In this case, the valves V12 and V14 are opened according to the amount of gas required in the fuel cell FC. Control the degree. For example, it can be proposed to adjust the openings of these valves V12 and V14 so that the outlet pressure of the fuel cell FC, that is, the pressure in the pipes 3 and 4 becomes a constant pressure.

ここで、水電解運転から燃料電池運転に切替えるときには、特開２００６−１２７８０７号公報に開示されているように、配管５、６から不活性の乾燥ガスを導入し、燃料電池ＦＣの内部基材を適度に乾燥させることでこの切替を安全かつ円滑に繰返し行うことができる。このとき、内部基材が適度に乾燥したかを判断する指標として抵抗計１６の値を用い、そこからのセパレータ２７、２８間の導体抵抗の出力信号を制御装置１７に取込み、予め組込んだシーケンスで切替が行われる。   Here, when switching from the water electrolysis operation to the fuel cell operation, as disclosed in Japanese Patent Application Laid-Open No. 2006-127807, an inert dry gas is introduced from the pipes 5 and 6, and the internal substrate of the fuel cell FC is introduced. This switching can be repeated safely and smoothly by appropriately drying. At this time, the value of the resistance meter 16 is used as an index for judging whether or not the internal substrate has been appropriately dried, and the output signal of the conductor resistance between the separators 27 and 28 is taken into the control device 17 and incorporated in advance. Switching is performed in sequence.

図５に示したように、本実施の形態によれば、燃料電池運転時の酸化剤極側に水素を混入させる必要が無い。また水電解反応に十分な量の純水を循環させることで、性能回復過程において特段の制御が一切不要であり、任意の電流密度で任意の時間運転しても燃料電池ＦＣにダメージを与えることは無い。このとき循環させる純水の純度（導電率、有機成分等）は高純度であればあるほど望ましいが、導電率で１μＳ／ｃｍ以下、ＴＯＣで１ｐｐｍ以下であれば、燃料電池性能は十分に回復する。   As shown in FIG. 5, according to the present embodiment, it is not necessary to mix hydrogen into the oxidant electrode side during operation of the fuel cell. In addition, by circulating a sufficient amount of pure water for the water electrolysis reaction, no special control is required in the performance recovery process, and the fuel cell FC is damaged even if it is operated at any current density for any time. There is no. At this time, the purity (conductivity, organic components, etc.) of the pure water to be circulated is preferably as high as possible. However, if the conductivity is 1 μS / cm or less and the TOC is 1 ppm or less, the fuel cell performance is sufficiently recovered. To do.

次に電極面積２５０ｃｍ２の燃料電池を用いて本発明の効果を検証した。今回は近年の研究で明らかになった性能低下を加速させる２通りの条件で運転することで燃料電池性能を一旦低下させ、その状態から本方法によってどの程度まで性能が回復するかを検証した。なお、各セル間はセパレータで仕切られており、汚染物質が直接的に他のセルに移動することは無いため、ここでは単セルで検証した。 Next, the effect of the present invention was verified using a fuel cell having an electrode area of 250 cm 2 . This time, the fuel cell performance was temporarily reduced by operating under two conditions that accelerate the performance degradation revealed in recent research, and the extent to which the performance was recovered from this state by this method was verified. In addition, since each cell is partitioned off by a separator and the pollutant does not move directly to another cell, the verification was performed using a single cell here.

まずは起動停止サイクル運転について調べた。すなわち起動停止のサイクルを４ｈ、膜が不純物で汚染され易いようにＴＯＣで３ｐｐｍの純水を加湿用の純水として供給し、運転温度８０℃、電流密度０．６Ａ／ｃｍ２の繰返し運転を実施した。 First, the start / stop cycle operation was examined. That is, the start / stop cycle is 4 h, and 3 ppm of pure water is supplied as humidifying pure water by TOC so that the membrane is easily contaminated with impurities, and the operation temperature is 80 ° C. and the current density is 0.6 A / cm 2. Carried out.

その結果の一例を図６における左側の棒グラフ群に示す。同図に見られるように延べ運転時間で１００ｈ、起動停止回数で２５回の時点で、初期の電圧値７００mＶに対して６８２ｍＶまで低下した。この状態で発電を中止し、性能回復運転（水電解運転）を実施した。その後所定の方法で運転切替を行い、再度燃料電池運転をした結果、電圧値は６９８ｍＶまで回復した。その後も継続して同様の起動停止サイクル運転を繰返し、電圧値が６８０ｍＶまで低下するたびに性能回復運転を行った。その結果、延べ運転時間で約１０００ｈ、起動停止回数で約２５０回に渡り性能回復運転後の電圧値は６９８〜７０１mＶまで回復し続けた。   An example of the result is shown in the left bar graph group in FIG. As seen in the figure, the voltage dropped to 682 mV with respect to the initial voltage value of 700 mV when the total operation time was 100 h and the number of start and stop times was 25. In this state, power generation was stopped and performance recovery operation (water electrolysis operation) was performed. Thereafter, the operation was switched by a predetermined method, and the fuel cell operation was performed again. As a result, the voltage value recovered to 698 mV. Thereafter, the same start / stop cycle operation was repeated, and the performance recovery operation was performed each time the voltage value decreased to 680 mV. As a result, the voltage value after the performance recovery operation continued to recover to 698 to 701 mV for about 1000 hours in total operation time and about 250 times in starting and stopping.

ここで、より直接的に性能回復運転の効果を確認するために、発電中の燃料電池の内部抵抗を交流インピーダンス法で測定した。その結果を図７に示した。図７は実軸−虚軸座標に測定結果をプロットした複素インピーダンスプロットを示しており、これによれば、性能低下した状態では低下する前に比べ触媒の有効面積を表わす指標の一つである活性化過電圧成分（半円の直径）が増大しているが（図７中の黒い三角プロット）、性能回復運転によりその値がほぼ元に戻っていることがわかる（図７中の白抜きの四角プロット）。したがって本発明の性能回復運転により触媒の有効表面積が回復したことがわかる。なおこのときの今回の水電解の運転条件は、運転温度８０℃、電流密度１．０Ａ／ｃｍ２、循環水量０．５Ｌ／ｍｉｎ、運転時間１ｈとした。 Here, in order to confirm the effect of the performance recovery operation more directly, the internal resistance of the fuel cell during power generation was measured by the AC impedance method. The results are shown in FIG. FIG. 7 shows a complex impedance plot in which the measurement results are plotted on the real axis-imaginary axis coordinates, and according to this, it is one of the indexes representing the effective area of the catalyst in the state where the performance is deteriorated as compared with before the decrease. Although the activation overvoltage component (diameter of the semicircle) is increasing (black triangle plot in FIG. 7), it can be seen that the value is almost restored to the original value by the performance recovery operation (the white outline in FIG. 7). Square plot). Therefore, it can be seen that the effective surface area of the catalyst was recovered by the performance recovery operation of the present invention. The operating conditions for water electrolysis at this time were an operating temperature of 80 ° C., a current density of 1.0 A / cm 2 , a circulating water amount of 0.5 L / min, and an operating time of 1 h.

次は酸素側電位が、８００ｍＶ以上になるような低負荷での起動停止サイクル運転について調べた。すなわち、電流密度を０．１Ａ／ｃｍ２とし、起動停止サイクルを４ｈ、運転温度８０℃の繰返し運転を実施した。本条件にて延べ運転時間で１２０ｈ、起動停止回数で３０回の運転を行った後に電流密度が０．６Ａ／ｃｍ２の運転を実施し、低負荷運転を実施する前後の電圧値を比較した。 Next, the start / stop cycle operation at a low load in which the oxygen side potential is 800 mV or more was examined. That is, repeated operation was performed at a current density of 0.1 A / cm 2 , a start / stop cycle of 4 h, and an operating temperature of 80 ° C. Under this condition, the operation was performed for 120 hours in total operation time and 30 operations for starting and stopping, and then the operation was performed with a current density of 0.6 A / cm 2 , and the voltage values before and after the low load operation were compared. .

その結果、図６における右側の棒グラフ群に見られるように、低負荷運転前は６９９ｍＶであったものが、低負荷運転後は６５２ｍＶまで急激に低下した。その状態から性能回復運転をした結果、６９７ｍＶとほぼ最初の性能まで回復した。なお、性能回復運転を実施する前に、特開２００１−８５０３７号公報に開示されているような、純水を循環させることによる性能回復も試みた。   As a result, as can be seen in the bar graph group on the right side in FIG. 6, it was 699 mV before the low load operation, but rapidly decreased to 652 mV after the low load operation. As a result of performance recovery operation from this state, it recovered to the initial performance of 697 mV. Prior to performing the performance recovery operation, an attempt was made to recover the performance by circulating pure water as disclosed in JP-A-2001-85037.

その結果、８０℃の純水を酸化剤極側のみに２ｈ循環させた後の電圧値は６８１ｍＶであり、水電解運転のほうがより性能回復効果があることを確認した。なお、特開２００１−８５０３７号公報には、洗浄液を循環させた後燃料電池運転をするまでの操作についての記述はないが、本方法では前述のように、特開２００６−１２７８０７号公報に開示されているような、乾燥運転を伴う操作を用いた。   As a result, the voltage value after circulating pure water at 80 ° C. only to the oxidant electrode side for 2 h was 681 mV, and it was confirmed that the water electrolysis operation had a performance recovery effect. Although JP 2001-85037A does not describe the operation until the fuel cell is operated after circulating the cleaning liquid, this method is disclosed in JP 2006-127807 A as described above. An operation with a drying operation as used was used.

この場合でも、先の例と同様に交流インピーダンス法で発電中の燃料電池の内部抵抗値を測定した。図８に見られるように、この場合でも性能低下した状態では活性化過電圧成分が増大し、性能回復運転によりその値が減少することから、性能回復運転に触媒有効表面積の回復効果があることを再確認した。   Even in this case, the internal resistance value of the fuel cell during power generation was measured by the AC impedance method as in the previous example. As shown in FIG. 8, even in this case, the activated overvoltage component increases in the state where the performance is lowered, and the value is decreased by the performance recovery operation. Therefore, the performance recovery operation has a recovery effect on the catalyst effective surface area. Reconfirmed.

以上の結果から、燃料電池運転と水電解運転を交互に行うことにより燃料電池性能を長期に渡りに維持できることがわかる。その運用方法の一例として、前述したように性能回復運転時に生成した水素、酸素をガス貯蔵タンク１７、１８に貯蔵しておき、燃料電池運転時にその貯蔵したガスを利用することにより本システムのより効率的な運用が可能となる。   From the above results, it can be seen that the fuel cell performance can be maintained for a long time by alternately performing the fuel cell operation and the water electrolysis operation. As an example of the operation method, as described above, the hydrogen and oxygen generated during the performance recovery operation are stored in the gas storage tanks 17 and 18, and the stored gas is used during the fuel cell operation. Efficient operation is possible.

以上説明したように、前記した回復方法を実施すれば、燃料電池運転時の燃料極→酸化剤極へのプロトンの移動量に比べて、数〜１０数倍ものプロトンを逆方向に流すことができ、従来技術よりも汚染物質を強力かつ速やかに排出することが可能となる。このため、従来技術以上に耐久性を向上させる効果を有している。 As described above, when the recovery method described above is performed, protons may flow in the reverse direction several to several tens of times compared to the amount of proton movement from the fuel electrode to the oxidizer electrode during fuel cell operation. It is possible to discharge pollutants more powerfully and more quickly than in the prior art. For this reason , it has the effect which improves durability rather than a prior art .

前記したシステム例は、性能回復運転である水電解運転時において、燃料電池ＦＣにおける燃料電池運転時の酸化剤極側、すなわち流路２８ａの集電体２６側に純水を供給するようにしていたが、本発明においては、水電解運転時において酸化剤極側のみならず燃料極側に純水を供給する。 In the system example described above, pure water is supplied to the oxidant electrode side in the fuel cell operation of the fuel cell FC, that is, the current collector 26 side of the flow path 28a during the water electrolysis operation which is the performance recovery operation. and although, in the present invention, for supplying pure water to the fuel electrode side as well as the oxidant electrode side only during water electrolysis operation.

これを図に基づいて具体的に説明すれば、図９に示した例においては、図２に示したシステム例に対して、タンク１１と配管３との間に配管４１を接続し、この配管４１にポンプ４２、バルブＶ６を設け、配管３にバルブＶ７を設けたものである。かかる構成により、タンク１１内の純水を、ポンプ４２によって配管４１、配管３を経由して燃料電池ＦＣの燃料極側、すなわち図３に示した、流路２７ａの集電体２５側に純水が供給できるようになっている。   This will be specifically described with reference to the drawings. In the example shown in FIG. 9, a pipe 41 is connected between the tank 11 and the pipe 3 in the system example shown in FIG. 41 is provided with a pump 42 and a valve V6, and a pipe 3 is provided with a valve V7. With this configuration, pure water in the tank 11 is purified by the pump 42 via the pipe 41 and the pipe 3 to the fuel electrode side of the fuel cell FC, that is, to the current collector 25 side of the flow path 27a shown in FIG. Water can be supplied.

そして水電解運転時においては、まずバルブＶ１、Ｖ２は閉鎖し、バルブＶ３、Ｖ６は開放、バルブＶ４、Ｖ７は閉鎖する。そしてタンク１２に貯蔵した純水をポンプ１３によって、配管４を通じて燃料電池ＦＣにおける燃料電池運転時の酸化剤極側、すなわち流路２８ａの集電体２６側に供給すると共に、タンク１１に貯蔵した純水をポンプ４２によって、配管３を通じて燃料電池ＦＣにおける燃電池運転時の燃料極側、すなわち流路２７ａの集電体２５側に供給する。このとき既述したように、外部電源１５の陰極を集電体２５に、陽極を集電体２６に接続して、集電体２５、２６に対して電流を供給する。   During the water electrolysis operation, the valves V1 and V2 are first closed, the valves V3 and V6 are opened, and the valves V4 and V7 are closed. The pure water stored in the tank 12 is supplied by the pump 13 to the oxidant electrode side during the fuel cell operation in the fuel cell FC, that is, to the current collector 26 side of the flow path 28 a through the pipe 4 and stored in the tank 11. Pure water is supplied by the pump 42 to the fuel electrode side during the fuel cell operation in the fuel cell FC, that is, to the current collector 25 side of the flow path 27a through the pipe 3. At this time, as described above, the cathode of the external power source 15 is connected to the current collector 25 and the anode is connected to the current collector 26 to supply current to the current collectors 25 and 26.

このように水電解運転時に、酸化剤極側のみならず燃料極側にも純水を供給することで、より確実に不純物をセル外に排出することが可能である。すなわち水電解運転で膜内から排出された不純物は、まず燃料極側の集電体２５を通って流路２７ａへ排出され、次にセル外に排出されるが、もしこの不純物がセル外に排出されずセル内部に残留した状態で燃料電池運転を開始すると、一度膜内から排出した不純物が再度膜内に侵入する可能性がある。したがって、燃料極側にも純水を循環することで、膜表面を洗い流す作用が加わり、膜内から排出された不純物をセル外まで確実に排出することが可能である。   As described above, by supplying pure water not only to the oxidant electrode side but also to the fuel electrode side during the water electrolysis operation, impurities can be more reliably discharged out of the cell. That is, the impurities discharged from the membrane in the water electrolysis operation are first discharged to the flow path 27a through the current collector 25 on the fuel electrode side, and then discharged to the outside of the cell. If the fuel cell operation is started in a state where it is not discharged and remains inside the cell, the impurities once discharged from inside the film may enter the film again. Therefore, by circulating pure water also on the fuel electrode side, an action of washing the membrane surface is added, and impurities discharged from inside the membrane can be surely discharged to the outside of the cell.

またこのように酸化剤極側のみならず燃料極側にも純水を供給すると、水電解運転（回復運転）の安全性が高まるものである。すなわち水電解運転では、電気分解するための純水が必要であるが、この純水は、電気分解反応時に発生する熱をセル外へ除去（冷却）する役目も果たしている。ここでもしポンプ１３等の故障により酸化剤極側への純水の供給が停止してしまうと、電気分解するものがなくなるため、膜内の水を分解し始める。膜の抵抗値は、膜の湿潤状態に依存するため、乾燥するほど抵抗が高くなりジュール熱が増加する。しかし、純水がないためセル外へ熱を除去できず内部に熱がこもってしまう。膜の耐熱温度は１００℃前後と言われており、それを超えると膜が溶け始める。すると膜が本来果たすべき燃料極側−酸化剤極側のシール性が失われ、両極のガスが混合し短絡状態（＝電池の破損）となる。この点図９に示したように、燃料極側に対しても純水を供給することで、燃料極側の流路２７ａ内の純水が電気分解に供され、そのような事態は発生しない。したがってより安全に水電解運転（回復運転）を実施することができる。   In addition, when pure water is supplied not only to the oxidant electrode side but also to the fuel electrode side in this way, the safety of water electrolysis operation (recovery operation) is enhanced. That is, in the water electrolysis operation, pure water for electrolysis is required, but this pure water also serves to remove (cool) the heat generated during the electrolysis reaction to the outside of the cell. Here, if the supply of pure water to the oxidizer electrode side is stopped due to a failure of the pump 13 or the like, there will be no electrolysis, so the water in the membrane will start to decompose. Since the resistance value of the film depends on the wet state of the film, the resistance increases and the Joule heat increases as the film dries. However, since there is no pure water, heat cannot be removed outside the cell, and heat is trapped inside. The heat-resistant temperature of the film is said to be around 100 ° C., and when it exceeds that, the film starts to melt. Then, the sealing property between the fuel electrode side and the oxidant electrode side that should be fulfilled by the membrane is lost, and the gas of both electrodes is mixed, resulting in a short circuit state (= battery damage). As shown in FIG. 9, by supplying pure water also to the fuel electrode side, the pure water in the fuel electrode side flow path 27a is subjected to electrolysis, and such a situation does not occur. . Therefore, the water electrolysis operation (recovery operation) can be performed more safely.

なお燃料電池運転から水電解運転に切り替える際には、たとえば燃料電池ＦＣの運転中の電圧値を監視し、初期の電圧値に対して２０ｍＶ以上の電圧低下を検知した時点で性能回復運転待機状態とし、その後燃料電池ＦＣの燃料電池運転を停止した後に、水電解運転に切り替えるようにすれば、効率よくかつ適切に性能回復運転を実施することができる。なおこのような切り替え制御は、燃料電池ＦＣの電圧値を検出、監視する適宜の電圧センサからの検出信号に基づいて、制御装置１４で自動的に切り替え制御することが容易である。   When switching from the fuel cell operation to the water electrolysis operation, for example, the voltage value during operation of the fuel cell FC is monitored, and the performance recovery operation standby state is detected when a voltage drop of 20 mV or more is detected with respect to the initial voltage value. Then, after stopping the fuel cell operation of the fuel cell FC, switching to the water electrolysis operation makes it possible to efficiently and appropriately perform the performance recovery operation. Such switching control can be easily performed automatically by the control device 14 based on a detection signal from an appropriate voltage sensor that detects and monitors the voltage value of the fuel cell FC.

さらにまた、性能回復運転である水電解運転から再び燃料電池運転に戻す場合には、たとえば導電率が１μＳ／ｃｍ以下、ＴＯＣが１ｐｐｍ以下の純水を供給して水電解運転を行なう場合、燃料電池運転時の２倍の電流密度で１時間程度運転した後、燃料電池運転に戻すようにすることが提案できる。このように水電解運転時には、燃料電池運転時よりも大きい電流密度で水電解を実施することが好ましい。   Furthermore, when returning from the water electrolysis operation which is the performance recovery operation to the fuel cell operation again, for example, when performing the water electrolysis operation by supplying pure water having a conductivity of 1 μS / cm or less and a TOC of 1 ppm or less, It can be proposed to return to fuel cell operation after operating for about 1 hour at twice the current density during battery operation. Thus, during water electrolysis operation, it is preferable to perform water electrolysis with a larger current density than during fuel cell operation.

本発明は、固体高分子形燃料電池の性能を回復させる際に有用である。   The present invention is useful in restoring the performance of a polymer electrolyte fuel cell.

膜内プロトンの輸送現象を模式的に示した説明図である。It is explanatory drawing which showed typically the transport phenomenon of the proton in a film | membrane. 実施の形態の前提となるシステム例の配管系統を示す説明図である。It is explanatory drawing which shows the piping system of the system example used as the premise of embodiment. 図２のシステム例で用いた固体高分子形燃料電池の内部の構造を模式的に示した説明図である。It is explanatory drawing which showed typically the internal structure of the polymer electrolyte fuel cell used with the system example of FIG. 図２のシステム例で用いた固体高分子形燃料電池の燃料運転時の様子を模式的に示した説明図である。It is explanatory drawing which showed typically the mode at the time of the fuel driving | operation of the polymer electrolyte fuel cell used in the system example of FIG. 図２のシステム例で用いた固体高分子形燃料電池の水電解運転時の様子を模式的に示した説明図である。It is explanatory drawing which showed typically the mode at the time of the water electrolysis driving | operation of the polymer electrolyte fuel cell used in the system example of FIG. 性能低下試験の前後および性能回復運転後の出力電圧を示すグラフである。It is a graph which shows the output voltage before and after a performance fall test and after a performance recovery driving | operation. 電流密度が０．６Ａ／ｃｍ２のときの運転性能低下試験の前後および性能回復運転後の内部抵抗割合を示す複素インピーダンスプロットに基づくグラフである。It is a graph based on the complex impedance plot which shows the internal resistance ratio before and after the driving performance degradation test when the current density is 0.6 A / cm 2 and after the performance recovery driving. 電流密度が０．１Ａ／ｃｍ２のときの性能低下試験の前後および性能回復運転後の内部抵抗割合を示す複素インピーダンスプロットに基づくグラフである。It is a graph based on the complex impedance plot which shows the internal resistance ratio before and after the performance deterioration test when the current density is 0.1 A / cm 2 and after the performance recovery operation. 実施の形態で用いた固体高分子形燃料電池の配管系統を示す説明図である。It is an explanatory view showing a piping system of a solid polymer fuel cell used in the embodiment.

符号の説明Explanation of symbols

１、２、３、４、５、６、７、１７ａ、１７ｂ、１８ａ、１８ｂ、４１
配管
１１、１２ タンク
１３、４２ ポンプ
１４ 制御装置
１５ 外部電源
１６ 抵抗計
１７、１８ ガス貯蔵タンク
２１ プロトン伝導性固体高分子膜
２２、２３ 触媒
２４ 膜電極接合体
２５、２６集電体
２７、２８ セパレータ
２７ａ、２８ａ 流路
３１ 負荷
ＦＣ 燃料電池 1, 2, 3, 4, 5, 6, 7, 17a, 17b, 18a, 18b, 41
Piping 11, 12 Tank 13, 42 Pump 14 Control device 15 External power supply 16 Resistance meter 17, 18 Gas storage tank 21 Proton conductive solid polymer membrane 22, 23 Catalyst 24 Membrane electrode assembly 25, 26 Current collector 27, 28 Separator 27a, 28a Flow path 31 Load FC Fuel cell

Claims (2)

固体高分子形燃料電池における、燃料電池運転時の酸化剤極側及び燃料電池運転時の燃料極側の双方に対して、導電率が１μＳ／ｃｍ以下、ＴＯＣが１ｐｐｍ以下である純水を供給するとともに、前記固体高分子形燃料電池の集電体に対して、燃料電池運転時とは逆方向の電流を流すように外部電源から電力を供給して前記純水を電気分解させる水電解運転を行なって、固体高分子形燃料電池の性能を回復させる方法を実施するためのシステムであって、
前記固体高分子形燃料電池内の燃料極側に通じ、水電解運転時に生成した水素の排出経路及び燃料電池運転時には燃料の供給経路となる配管１、燃料電池運転時の燃料排出経路となる配管３と、
前記固体高分子形燃料電池内の酸化剤極側に通じ、水電解運転時に生成した酸素の排出経路及び燃料電池運転時には酸素の供給経路となる配管２と、燃料電池運転時の酸化剤排出経路となる配管４とを有し、
前記配管１には、純水を貯蔵するとともに、気液分離機能を有するタンク１１が設けられ、タンク１１の上部には、バルブＶ１１を介してガス貯蔵タンク１７が設けられ、タンク１１の下部には、配管３にタンク１１内の純水を供給する配管４１が接続され、
前記配管２には、純水を貯蔵するとともに、気液分離機能を有するタンク１２が設けられ、タンク１２の上部には、バルブＶ１３を介してガス貯蔵タンク１８、が設けられ、タンク１２の下部には、配管４にタンク１２内の純水を供給する配管７が接続され、
水電解運転時には、タンク１１内の純水を配管４１を介して配管３に流し、タンク１２内の純水を配管７を介して配管４に流し、
水電解運転時に生成して配管１から出た水素は、タンク１１において気液分離した後ガス貯蔵タンク１７に貯蔵し、配管２から出た酸素は、タンク１２において気液分離した後ガス貯蔵タンク１８に貯蔵して、これら貯蔵した水素及び酸素を、燃料電池運転時の燃料及び酸化剤として用いるようにし、
燃料電池運転時には、ガス貯蔵タンク１７に貯蔵されている水素を、配管１７ｂ、配管１からタンク１１へ送って当該タンク１１で加湿して前記固体高分子形燃料電池に供給するとともに、ガス貯蔵タンク１８に貯蔵されている酸素を、配管１８ｂ、配管２からタンク１２へ送って当該タンク１２で加湿して前記固体高分子形燃料電池に供給するように構成されたことを特徴とする、固体高分子形燃料電池の性能回復方法を実施するためのシステム。 In the polymer electrolyte fuel cell, pure water having a conductivity of 1 μS / cm or less and a TOC of 1 ppm or less is supplied to both the oxidant electrode side during fuel cell operation and the fuel electrode side during fuel cell operation. And a water electrolysis operation in which the pure water is electrolyzed by supplying electric power from an external power source to the current collector of the polymer electrolyte fuel cell so that a current in a direction opposite to that during fuel cell operation flows. the turned row, a system for implementing the method of restoring the performance of the polymer electrolyte fuel cell,
A pipe 1 that leads to the fuel electrode side in the polymer electrolyte fuel cell and serves as a discharge path for hydrogen generated during water electrolysis operation, a fuel supply path during fuel cell operation, and a fuel discharge path during fuel cell operation 3 and
A pipe 2 that leads to the oxidant electrode side in the polymer electrolyte fuel cell and serves as a discharge path for oxygen generated during water electrolysis operation and a supply path for oxygen during fuel cell operation, and an oxidant discharge path during fuel cell operation And piping 4 to be
The pipe 1 is provided with a tank 11 for storing pure water and having a gas-liquid separation function. A gas storage tank 17 is provided above the tank 11 via a valve V11. Is connected to a pipe 41 for supplying pure water in the tank 11 to the pipe 3;
The pipe 2 is provided with a tank 12 that stores pure water and has a gas-liquid separation function. A gas storage tank 18 is provided above the tank 12 via a valve V13. Is connected to a pipe 7 for supplying pure water in the tank 12 to the pipe 4.
At the time of water electrolysis operation, pure water in the tank 11 is caused to flow to the pipe 3 via the pipe 41, and pure water in the tank 12 is caused to flow to the pipe 4 via the pipe 7,
Hydrogen generated during the water electrolysis operation and discharged from the pipe 1 is gas-liquid separated in the tank 11 and then stored in the gas storage tank 17, and oxygen discharged from the pipe 2 is gas-liquid separated in the tank 12 and then stored in the gas storage tank 17. 18 and use these stored hydrogen and oxygen as fuel and oxidant during fuel cell operation,
During operation of the fuel cell, the hydrogen stored in the gas storage tank 17 is sent from the pipe 17b and the pipe 1 to the tank 11, humidified in the tank 11, and supplied to the polymer electrolyte fuel cell. The oxygen stored in 18 is sent from the pipe 18b and the pipe 2 to the tank 12, humidified in the tank 12, and supplied to the polymer electrolyte fuel cell. A system for carrying out a performance recovery method of a molecular fuel cell. 固体高分子形燃料電池の運転中の電圧値を監視し、初期の電圧値に対して２０ｍＶ以上の電圧低下を検知した時点で固体高分子形燃料電池の運転を停止し、その後固体高分子形燃料電池における、燃料電池運転時の酸化剤極側及び燃料電池運転時の燃料極側の双方に対して、導電率が１μＳ／ｃｍ以下、ＴＯＣが１ｐｐｍ以下である純水を供給するとともに、前記固体高分子形燃料電池の集電体に対して、燃料電池運転時とは逆方向の電流を流すように外部電源から電力を供給して前記純水を電気分解させる水電解運転を行なって、固体高分子形燃料電池の性能を回復させる方法を実施するたのシステムであって、
前記固体高分子形燃料電池内の燃料極側に通じ、水電解運転時に生成した水素の排出経路及び燃料電池運転時には燃料の供給経路となる配管１、燃料電池運転時の燃料排出経路となる配管３と、
前記固体高分子形燃料電池内の酸化剤極側に通じ、水電解運転時に生成した酸素の排出経路及び燃料電池運転時には酸素の供給経路となる配管２と、燃料電池運転時の酸化剤排出経路となる配管４とを有し、
前記配管１には、純水を貯蔵するとともに、気液分離機能を有するタンク１１が設けられ、タンク１１の上部には、バルブＶ１１を介してガス貯蔵タンク１７が設けられ、タンク１１の下部には、配管３にタンク１１内の純水を供給する配管４１が接続され、
前記配管２には、純水を貯蔵するとともに、気液分離機能を有するタンク１２が設けられ、タンク１２の上部には、バルブＶ１３を介してガス貯蔵タンク１８、が設けられ、タンク１２の下部には、配管４にタンク１２内の純水を供給する配管７が接続され、
水電解運転時には、タンク１１内の純水を配管４１を介して配管３に流し、タンク１２内の純水を配管７を介して配管４に流し、
水電解運転時に生成して配管１から出た水素は、タンク１１において気液分離した後ガス貯蔵タンク１７に貯蔵し、配管２から出た酸素は、タンク１２において気液分離した後ガス貯蔵タンク１８に貯蔵して、これら貯蔵した水素及び酸素を、燃料電池運転時の燃料及び酸化剤として用いるようにし、
燃料電池運転時には、ガス貯蔵タンク１７に貯蔵されている水素を、配管１７ｂ、配管１からタンク１１へ送って当該タンク１１で加湿して前記固体高分子形燃料電池に供給するとともに、ガス貯蔵タンク１８に貯蔵されている酸素を、配管１８ｂ、配管２からタンク１２へ送って当該タンク１２で加湿して前記固体高分子形燃料電池に供給するように構成されたことを特徴とする、固体高分子形燃料電池の性能回復方法を実施するためのシステム。 The voltage value during operation of the polymer electrolyte fuel cell is monitored, and when the voltage drop of 20 mV or more is detected with respect to the initial voltage value, the operation of the polymer electrolyte fuel cell is stopped, and then the polymer electrolyte fuel cell in the fuel cell, for both the fuel electrode side at the oxidant electrode side and the fuel cell operation at the time of fuel cell operation, conductivity 1 [mu] S / cm or less, with TOC supplies pure water is 1ppm or less, the For the current collector of the polymer electrolyte fuel cell, water electrolysis operation is performed to electrolyze the pure water by supplying electric power from an external power source so that a current in the direction opposite to that during fuel cell operation flows. A system for carrying out a method for restoring the performance of a polymer electrolyte fuel cell, comprising:
A pipe 1 that leads to the fuel electrode side in the polymer electrolyte fuel cell and serves as a discharge path for hydrogen generated during water electrolysis operation, a fuel supply path during fuel cell operation, and a fuel discharge path during fuel cell operation 3 and
A pipe 2 that leads to the oxidant electrode side in the polymer electrolyte fuel cell and serves as a discharge path for oxygen generated during water electrolysis operation and a supply path for oxygen during fuel cell operation, and an oxidant discharge path during fuel cell operation And piping 4 to be
The pipe 1 is provided with a tank 11 for storing pure water and having a gas-liquid separation function. A gas storage tank 17 is provided above the tank 11 via a valve V11. Is connected to a pipe 41 for supplying pure water in the tank 11 to the pipe 3;
The pipe 2 is provided with a tank 12 that stores pure water and has a gas-liquid separation function. A gas storage tank 18 is provided above the tank 12 via a valve V13. Is connected to a pipe 7 for supplying pure water in the tank 12 to the pipe 4.
At the time of water electrolysis operation, pure water in the tank 11 is caused to flow to the pipe 3 via the pipe 41, and pure water in the tank 12 is caused to flow to the pipe 4 via the pipe 7,
Hydrogen generated during the water electrolysis operation and discharged from the pipe 1 is gas-liquid separated in the tank 11 and then stored in the gas storage tank 17, and oxygen discharged from the pipe 2 is gas-liquid separated in the tank 12 and then stored in the gas storage tank 17. 18 and use these stored hydrogen and oxygen as fuel and oxidant during fuel cell operation,
During operation of the fuel cell, the hydrogen stored in the gas storage tank 17 is sent from the pipe 17b and the pipe 1 to the tank 11, humidified in the tank 11, and supplied to the polymer electrolyte fuel cell. The oxygen stored in 18 is sent from the pipe 18b and the pipe 2 to the tank 12, humidified in the tank 12, and supplied to the polymer electrolyte fuel cell. A system for carrying out a performance recovery method of a molecular fuel cell.
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