報告書番号

W99007

タイトル（和文）

ＭＣＦＣカソード性能表示式の高精度化 -水蒸気効果と反応メカニズム-

タイトル（英文）

Cathode performance equation modification of MCFC - Effete of steam on cathode performance equation and reaction mechanism -

概要 （図表や脚注は「報告書全文」に掲載しております）

溶融炭酸塩型燃料電池発電プラントでは、競合するガスタービン発電の近年の効率向上に伴い６０％程度の効率が求められ、運転圧力を７気圧から１２気圧程度へ上げることが考えられている。そこで、プラント効率計算に必要な性能表示式として当所が電気化学的理論に基づき開発した式を、高圧でしかも水蒸気が含有されるプラント条件で検証し、さらに、電気化学理論に基づき性能表示式と反応メカニズムを考察した。加圧で水蒸気を含む実験結果から、１２気圧でカソード水蒸気が存在する条件でも高精度な式を開発し、国のプラント概念設計に採用された。性能表示式の電池仕様による形式変化を電気化学的に考察し、反応メカニズムを提案し、各式中の３つの係数を物性値に関連づけた。それら係数の比はセル仕様によらず一定となり、同一仕様セル性能のばらつきは電極実面積に起因することが示唆された。

概要 （英文）

In the molten carbonate fuel cell power generation systems, the cathode gas contains steam. However, MCFC performance is usually measured using dry cathode gas. Effect of steam contained in the cathode gas is not known. In this study, effect of the steam has been elucidated. Furthermore, the previous equation of the cathode reaction resistance was improved and a cathode reaction mechanism was proposed.Steam effect is not small and has to be considered in estimation of cathode performance especially on plant condition since cathode gas of plant condition contained approximately 15% of cathode gas flow rate. Cathode reaction resistance has been studied with data obtained using different single cells which use Li/K carbonate or Li/Na carbonate as the electrolyte. It was found that the form of cathode reaction resistance equation depends on cathode structure. Diffusion processes in gas and liquid phases are very important. The magnitudes of these processes determine the form of the equation. A mechanism of cathode reaction has been proposed to explain the equation. The mechanism is able to explain reasonably change of equation form with cathode structure and electrolyte fill level of the cathode.Furthermore, the relationships among parameters of the equations were investigated. Ratios of these parameters are constant. This result was explained by the reaction mechanism. In addition, it is suggested that actual effective cathode area is only effective parameter. At last, number of parameters of the equation was reduced from three to one.

報告者

キーワード