Molten Carbonate Fuel Cell (MCFC) has high potential in being used as an energy converter of various fuels to electricity and heat. MCFC yields few envioronmental polutions and meets a reduction in the green house problem. Development of indirect internal reforming molten carbonate fuel cell (IIR-MCFC) was initiated by the Kansai Electric Power Company and Mitsubishi Electric Corporation. IIR-MCFC has several advantages. (1) Higher efficiency is expected because of efficient utilization of heat from cell reaction to reforming reaction. (2) Longer life compared with direct internal reforming MCFC is expected by means of loading reforming catalyst in the cell separated from the electrolyte vapor which causes deactivation of the reforming catalyst.
A 3kW, a 10kW, a 30kW and a 100kW class stack were operated successfully. Output power of 100kW class stack generated 109kW in IIR mode. (direct methane feed) In the test of the 30kW and the 100kW class stack, PSA (pressure swing adsorption) to separate carbon dioxide from the anode exhaust gas is installed in the anode gas recycle loop to the cathode.

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Molten carbonate fuel cell (MCFC) power plant is expected to be one of the most promising future power generaton system for the electric utilities because of its high efficiency, environmental suitability and capability of using coal as fuel. To get such attractive performance, it is necessary for the plant to adopt the gas recycling operation system. The authors tested a 6 kW class MCFC stack with three types of gas recyclings such as cathode, anode and carbon dioxide ones, including pressurized conditions.
This paper describes the test results and the effects of the gas recycling operations. Cathode gas recycling is proved to be able to control the stack temperature and give the flexibility for setting oxygen utilization. Anode gas recycling is proved to be able to suppress the methane formation and decrease the deviation of the stacked cell voltages. Including the starting-up process, it is proved that the electricity can be generated from the stack without supplying carbon dioxide from outside the system by carbon dioxide gas recycling. In such a process using burner for carbon dioxide gas recycling, burner temperature must be controlled in the certain value. It is important to adjust the fuel supplying rate, load current and cathode gas recycling ratio each other. At load change process, constant gas utilization operation is effective not to change the burner temperature.

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In Direct Internal Reforming Molten Carbonate Fuel Cells(DIR-MCFC)deterioration of catalytic activity takes place in the anode channel due to both the liquid-phase pollution and vapor-phase pollution. The liquid-phase pollution meant that catalytic activity is deteriorated by the molten salt's(62 Li₂CO₃/38K₂CO₃)adhering to the catalyst. It can be solved by installing the protective barrier in the pollutant pathway. On the other hand, the vapor-phase pollution meant that that catalytic activity is deteriorated by KOH adhering to the catalyst. Because the vapor-phase pollution is caused in the entire electrode, an effective defense method has not established yet. Moreover, a reactivation method of vapor-phase polluted catalyst has not been developed yet. In order to study the reactivation method, the adhesion form of potassium compounds in the polluted catalyst under the various gas conditions was evaluated by using a thermogravimertic analyzer in which water vapor can feed. Additionally, the activity of catalyst treated demonstratively was also tested by a differential reactor. As a result, KOH changes to K₂CO₃ under the condition which CO₂ concentration is larger than 25%. The catalyst with K₂CO₃ cannot reactive. However, the activity of polluted catalyst is revived until 80% of initial activity by controlling the gas species concentration, especially for CO₂. Based on the results obtained by these fundamental experiments, the reactivation methods of polluted catalyst are proposed as follows; i)Catalyst should load more in the upstream in the anode. ii)In order to reactive the polluted catalyst, the ratio of H₂O to CH₄ in the fuel should increase, when DIR-MCFC is under operation. iii)Gas compositions under cell maintenance mode should be applied in the case that power generation quits.

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Recently, to suppress the Nickel dissolution from the NiO cathode, Li/Na carbonate tends to be used as the electrolyte of molten carbonate fuel cells instead of Li/K carbonate. With Li/Na carbonate electrolyte, due to the higher ionic conductivity and the lower solubility of NiO, the decay rate of the stacks is expected to decrease. The single cell with Li/Na was operated over 12, 000 hours, resulting that the decay rate of the stack was presumed 3 mV/1000 hours. This value is less than that of the stack with Li/K carbonate, 4.5 mV/1000 hours. This presumption was agreed with that of the decay rate of the stack with Li/Na electrolyte operated over 6000 hours. Moreover, the effect of the electrolyte loss rate on the performance decay was deducted. The performance decay of 1.8 mV/1000 hours was expected for the stack equiped both with Li/Na carbonate and the advanced cathode current collector (slit firm type).

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Fuel cells, which have been given much attention in recent years, are now actively being studied and developed. However, their dynamic behaviors have not been fully discussed due to their complicated structures. This paper first explains the nonlinear dynamic models which show temperature behaviors by considering heat and mass balances in the cell. Then, we attempted to construct a control system by using feedback linearization to compensate for the effect of load change. Finally, it is shown by computer simulation that this system is quite effective.

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In this paper, the paragenesis of minerals in the Hoei mine is presented with some remarks on the mineralogical properties of kutnahorite.
The Ichigo (no.1) ore body of the Hoei mine is a massive deposit of Sn, Zn and iron sulfide formed by replacement of the Silurian limestone bed. From this ore body, there have been found various kinds of ore and gangue minerals such as: garnet, clinopyroxene, axinite, tourmaline, vesuvianite, quartz, pyrrhotite, chalcopyrite, arsenopyrite, pyrite, marcasite, sphalerite, galena, native bismuth, herzenbergite, franckeite, jamesonite, cassiterite, stannite, malayaite, fluorite, sericite and carbonate minerals. The species of carbonate minerals are ferromanganoan dolomite, magnesian kutnahorite, kutnahorite, calcian rhodochrosite, ferroan magnesite and manganoan calcite, and they have been crystallized at the later stage of mineralization in this mine.
The kutnahorite in this mine is white, yellow or pinkish in color, and platy or leaf-like in external shape, reaching to 5 cm in maximum length. Its specific gravity ranges from 2.98 to 3.18 by picnometer method. Optically negative, and some examples of refractive indices are ω=1.717-1.731, ε=1.524-1.529. Unit cell constants, a₀ = 4.861-4.869 Å, c₀=16.24-16.37 Å. The range of chemical composition of kutnahorite is fairly wide, as shown in Table 4 and 5.
Judging from the mode of occurence, microscopic observations and the compositional changes detected by EPMA, the crystallization sequence of the carbonate minerals is suggested as follows : dolomite-ferromanganoan dolomite-magnesian kutnahorite-kutnahorite-calcian rhodochrosite-manganoan calcite.

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This paper first presents a mathematical model which describes the temperature variations at each place in the molten carbonate fuel cell based upon the thermal and material balances and electrochemical reaction in the electrodes. Then, the coefficients of these derived dynamic equations are all nondimensionalized. Since these are partial differential equations with respect to the non-dimensional place and time, they are approximated by using the Method of Weighted Residuals and dynamic responses of the temperatures in the cell for load change are shown. The theoretical and experimental results are in good agreement. The difference between the counterflow and parallelflow types of fuel and oxidizing gases is discussed.

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鹿児島県喜界島北東部で掘削されたSTb-1コアとSTb-2コアを用いて，炭素・酸素同位体組成による地表露出面の認定とそれに基づく海水準変動の復元を行った．その結果，STb-1コアで3層準，STb-2コアで2層準の炭素・酸素同位体組成の負方向へのシフトが認められ，岩相，鉱物組成および続成組織の結果と合わせ，これらの負方向へのシフトは地表露出面であることが明らかとなった．また，STb-1・STb-2両コアの年代は，すでに年代の得られている露頭との対比から約62～52 kaであることが明らかとなった．
地表露出面から地表露出面までを１つの堆積ユニットとして，シーケンスⅠ～Ⅳの4つに区分すると，各シーケンスは氷床コアにおける酸素同位体曲線のIS-17～IS-14に対応すると考えられる．したがって，炭素・酸素同位体組成に基づく地表露出面の認定は，数千年程度の短周期の海水準変動に伴う地表露出面まで認定できると考えられ，浅海成岩を用いて詳細な海水準変動や堆積シーケンスを復元することに有効であると考えられる．

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In direct Internal Reforming Molten Carbonate Fuel Ceils (DIR MCFC) deterioration of catalytic activity takes place in the anode channel since the molten carbonate sometimes leaks and vaporizes there. In order to identify the process in DIR-MCFC, not only the activity of catalysts polluted in practical DIR-MCFC systems is evaluated, but also the important factors to deteriorate the catalytic activity are elucidated by using artificial polluted catalysts manufactured in this study. One of the deterioration factors in the practical systems affect quantitative and/or qualitative sintering. KOH mainly contaminates the catalyst rather than LiOH. The reaction rate constant of methane reforming reaction decrease with increasing the pollution ratio. However, the contamination does not act covering the active sites on the catalyst, and the overall reaction rate is not controlled by diffusion either into the pore or film surrounding the catalyst. If anything, vaporized KOH may enter into the micro pores, and results the decrease of active sites. In addition, the sintering phenomenon does not directly relate to the pollution. If the catalysts sinters, temperature of catalysts raises up since the reforming reaction indicates endothermic reaction. As the results, the temperature of catalyst attains the sintering temperature.

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The decay rate of the MCFC stacks was analyzed with the decay rate of the single cells operated over more than 10, 000 hours. Out of 4-5 mV/1000hours of the decay rate of standard stacks, 0.4 mV was estimated as the contribution of the interfacial resistance because of the corrosion of cathode current collectors. Moreover, 0.8 to 1.6 mV/1000hours was attributed to the performance decay due to the dissolution of the NiO cathodes. The rest of the decay rate about 3 mV/1000hours was assumed as the effect of the electrolyte loss. Therefore, the reduction of the electrolyte loss was thought to be the most important counter measure to reduce the decay rate. 60% of the standard electrolyte loss was assumed to be the target to achieve the decay rate of 2 mV/1000hours. Moreover, using the Li/Na carbonate which has lower solubility of Ni and higher ionic conductivity, the target was expected to be 70% of the electrolyte loss of the standard stacks.

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《研究背景》

　海溝型タービダイトは

補償深度よりも深く到達することから堆積時に鉱物はほとんど含まれない。固結した後の鉱物脈としてのみ鉱物は観察されてきた。しかし白亜系付加体タービダイト相の四国四万十帯野々川層と下津井層において、数十㎝から1m程度の領域に鉱物が異常に濃集している「濃集スポット」が報告された（中川・坂口2016）。この斑状鉱物は、周囲の砂岩粒子である石英や長石の圧力溶解変形をオーバープリントしている点や斑状鉱物と周囲の粒子との関係から、砂岩粒子を溶解しながら進む新たな流体移動のモデルの産状として考えられた（中川・坂口2016）。先行研究では濃集スポットの中心部に注目して研究されたが、中心部には鉱物脈があるなど構成の影響が懸念される。そこで本研究では鉱物について、濃集部形成初期の情報が残されていると考え調査を行った。

《地質概要》

　四国四万十帯は主にタービダイトが占め、本調査地域の白亜系下津井層、野々川層、中村層、砂岩優勢砂岩泥岩互層が主体で、砂岩層は石英や長石などの陸源砕屑物からなる。一般に珪質であり、鉱物脈を除けば有孔虫やナノ化石など石灰質微化石を含めて

鉱物はごく少ない。

《結果と考察》

　希塩酸による中和反応から今回新たに中村層での

濃集スポットの存在を確認した。こちらは10㎝程の大きさで先行研究に比べると小さい。鉱物が充填している様子が確認できる。これらの鉱物は微細なものが濃集しており中心部では大きく濃集している一方で外縁部に近づくほど濃集サイズは微細になっている。濃集した鉱物は極小で単一粒子としての観察が困難なものから数百μｍ程度の粒径で観察できるものもあり、これについては鉱物は再結晶した可能性がある。 また鉱物が観察されており、同様のメカニズムにより付加体砂岩中に普遍的に鉱物が存在している可能性がある。 この微細な斑状鉱物についてSEM-EDS分析を行った結果、微細な斑状鉱物には多くの場合においてSiが含まれることが分かった。Siの含有量についてはそれぞれ斑状鉱物によってばらつきがあり分布的な傾向は認められない。またこれらの斑状鉱物の試料からはFeやMgのピークはあまり得られず、斑状鉱物は基本的にカルサイトであるとみる。よって濃集スポットの砂岩粒子が溶解した産状と合わせて考えるとこのSiは流体が珪酸塩の砂岩粒子を溶解していたために混在していると考えることができる。

《引用文献》

中川美菜子・坂口有人，日本地質学会第123年大会，2016

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The major component of carbonate materials distributing in the earth's environment is calcium carbonate. Calcium carbonate has interesting characteristics, that is, it has three different crystal forms such as calcite, vaterite and aragonite. Thus, the distribution of minor chemical species between parent solution and calcium carbonate precipitate is delicate but interesting. Since the influences of various cations, anions and organic materials dissolved in a parent solution on the polymorphic crystallization and the distribution of minor elements were clarified by the present author, the synthesis of (Ca, Mg) CO₃ at low temperatures and pressures was first succeeded. It is also important that the amount of carbonate materials existing in the earth is very large and the greatest reservoir of carbon dioxide is carbonate materials. The present author estimated the sedimentation rate of marine carbonate through the geochemical balance of calcium ions after the careful examination on water-rock interaction on continent. He has tried to discuss the birth and evolution of air and sea through the discussion on those of carbon dioxide. Also the role of carbonate sedimentation in the sea on global warming has been clarified.

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The Pleistocene Ryukyu Group composed mainly of shallow-marine carbonates was deposited with hig-amplitude and short-termed glacioeustatic sea-level changes in the Middle Pleistocene age. We carried out core observation, carbon and oxygen isotopic analyses and XRD analyses to recognize subaerially exposure surfaces (SES), and to make clear the precise sea-level changes in the Middle Pleistocene age. For the purpose, six boring cores in the southern part of Miyako Island, southwestern Japan, were examined. As a result, the followings are revealed; (1) the Ryukyu Group of the study area is divided into 6 units, (2) each unit can be subdivided into two to four subunits based on SES, (3) each subunit was deposited during the interstadial period such as 5a, 5c and 5e during the Marine Oxygen Isotope Stage 5.

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岩は全堆積岩の∼20％を占め、その質量は1017トンにも及び、地球表層における二酸化炭素化学種の最大のプールである。しかし、その形成に微生物が関与することが分かってきたのは比較的最近であり、今後、さらに微生物要因の影響が強く認識されてくるであろう。たとえば、地質学界の積年の謎であった「低温ドロマイト生成」にも微生物が関与することが分かってきた。海底堆積物中の主要な生物地球化学プロセスに「メタンの嫌気的分解」があり、この産物として硫化水素と岩が生成されるが、この岩はどういう訳かMg含有量の高いカルサイトかドロマイトであることが多い。さらに、Halobacillus trueperiという好塩性バクテリアは沈殿作用を示すが、最近、われわれは石垣島沖のメタン湧出帯に自生する岩からこれに近縁の微生物を分離し、これが深海底での形成に関与している可能性を示唆した。

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