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ジェッティング流動層内グリッド領域でのガス移動の数学モデルを構築した.ジェットとアニュラス間のガス移動係数をフィッティングパラメーターとして, 両相のトレーサーガスの濃度分布を予測した.その結果をベンチスケール高温ジェッティング流動層内で測定した, 反応活性がないトレーサーガスの濃度分布と比べて検討した.分散板からのガス速度を最小流動化速度にし, 中心ノズルからのガス速度と層内の温度を変えて実験を行った.既往のデータおよび本実験結果から, ジェットとアニュラス間のガス交換係数の相関式をまとめた.モデルでの予測はジェットからアニュラスへのガスの浸透を考慮したとき, 実験結果によく一致した.

The present paper describes the results of the THF-solubles accumulation phenomenon in chars. The chars obtained from two Japanese bituminous coals, Akabira and Miike coals, were pyrolyzed in a TG and a free fall reactor under a nitrogen stream at atmospheric pressure. The maximum temperature range and heating rates, respectively, were 300-600°C and 3 or 100°C /min in the TG, and were 363-682°C, up to 1.0 × 105°C /min calculated in the free fall reactor. The properties of chars produced by each apparatus were analyzed and compared at the same conversion by THF extraction, H/C ratio and FT-IR. For each coal, rapid pyrolysis (100 and 105°C /min heating rates) allowed the THF-solubles fraction (thought of as heavy primary products) to accumulate in the char as heating rate increased. The maximum yields of THF-solubles in chars also appeared at low conversions, 0.15-0.2 for Akabira coal and 0.08-0.13 for Miike coal. Variations in H/C and Har/Hal ratios were small in this region of low conversion. From these results, we can say that heavy primary products still remain in char particles without secondary reaction.

テトラメトキシシランからトリメトキシシランへの気相転換の可能性についての検討を，熱力学的解析および実験により行った．テトラメトキシシランは，トリメトキシシランから塩素系化合物を経ずに多結晶シリコンを製造するという，新たに提案されたプロセスでの副生物である．0.1 MPa, 1023 Kの条件で，Si–Cu触媒を用いることにより，1%を超えるトリメトキシシラン収率が可能であることが示された．

A steady-state numerical simulation model, which takes account of hydrodynamics, mass transfer, heat transfer and reactions, was proposed for the grid zone of a jetting fluidized bed coal gasifier with a conical distributor. Temperatures of the particle and gas in the jet, compositions in the jet and the annulus as well as gas velocity, particle velocity, particle hold-up in the jet were calculated based on this model. The results have shown that the calculated particle temperature in the jet and compositions in the jet and annulus coincide with the experimental ones those were measured in a laboratory scale jetting fluidized bed gasifier.

The effects of ash content, ash layer heat and mass transfer on a single granulated char particle (10–18 mm in diameter) combustion in an air stream (12 cm s−1 in cold base) are studied. The transient temperature of various ash content char particle burning in the surrounding gas temperatures of 900 to 1200 K is simulated. Agreement between simulated and experiment results is obtained by adjusting the ash layer diffusion coefficient and heat conductivity, surface emissivity and the reaction rate constant. The reaction rate constant plays an important role in modeling the initial stage of char particle combustion even when the overall rate is ash layer diffusion controlled. It determines the particle heating rate in the initial stage of combustion, and then indirectly influences the peak temperature. The ash layer diffusion resistance affects the rate controlling processes and the pattern of the time-temperature profile. The higher ash content char particle burns with a lower peak temperature and earlier temperature decrease due to the lower ash layer porosity and lower ash layer diffusion coefficient. It is concluded that the high ash particle combustion is controlled by ash layer diffusion except in the initial stage of combustion. As for the lower ash content char particle, it is controlled mainly by reaction at lower ambient temperature and by film diffusion at a higher temperature in the earlier stage. However, in the last stage, it is controlled by ash layer diffusion. The transition occurs when the ash layer is formed and the diffusion resistance is significant, and it is at that time that the particle reaches its peak temperature.

For the production of refrigerators, CO2 emissions was estimated as affected by variations in estimation of CO2 emissions from electricity production, and differences in the process data and system boundaries used in the bottom-up approach. The results indicate that the amount of CO2 emitted in raw materials production was influenced by variations in CO2 per kWh electricity consumed, but the ratio of CO2 emis-sions from direct processrelated sources was not influenced. The amount of CO2 emis-sions in material production and the ratio of CO2 emissions in material production were influenced by the process data and system boundaries used in the calculations. In particular, as the process of aluminum ingots lead to large CO2 emissions, it is necessary to carefully consider the system boundary definition use when comparing estimates obtained from different data sources.The estimated CO2 emissions obtained via the bottom-up approach was then compared to that obtained using the Input-Output table analysis. The total CO2 emissions and the relative contribution of different sources in material production were influenced. It is also important to note that the calculated value using the Input-Output table is smaller than that from the bottom-up approach. It is reason that the data in the Input-Output table do not go into sufficient detail.

Ash formation mechanisms are summerized for combustion and gasification processes in this review. The effects of elements such as Na, S, Fe, Si, Al and the corresponding compounds contained in ash on the ash melting, sintering or agglomeration and slagging are discussed. Some attentions are emphasized in investigating the ash behaviors in combustion and gasification processes.

分散板中央にノズルを有する円筒型ジェッティング流動層コールドモデル内の粒子濃度分布を反射型光学繊維プローブを用いて測定し, ノズルガス流速, 分散板形状, 分散板ガス送入の有無がジェット内の諸現象に与える影響を検討した. コーン型分散板を用いた場合, ノズルガス流速を増加させると, 中心部の濃度が一定となるまでの高さとして定義したジェット高さは高くなり, その値は Yang らの式による推算値に近くなった.平板型分散板を使用した場合, コーン型分散板の場合と比べジェット内粒子濃度, ジェット径は増加し, ジェット高さは低くなった.分散板ガスを送入しない場合, 高濃度領域が高い位置まで形成され, ジェットの径・高さはともに増加した.粒子濃度はジェット内で減少した.

Effluent from the FCC process contains considerable concentrations of phenol, sulfide and ammonium ions. The pH of the effluent is around 9. In the present study, the possibility of the application of anion exchange membranes for its removal and recovery, was investigated. The equilibrium constant between phenol and hydroxide ions and the ion exchange capacity of a commercial anion exchange membrane were determined. The membrane was sandwiched between two glass cells filled with a phenol solution at pH 9, fed and withdrawn continuously to keep the phenol concentration constant, and a sodium hydroxide solution at various pH, respectively. The permeation rate increased with pH and reached a plateau at above pH 13. The permeation rate was measured for various concentrations of phenol in the feed side, keeping the pH of the strip side at 13. The rate linearly increased with the phenol concentration and reached a plateau at concentration greater than 1 mol/m3. The apparent diffusion coefficient of phenol in the membrane was determined from the plateau value. At a concentration of less than 1 mol/m3, the rate was found to be controlled by boundary film resistance. It was also found that the permeation rate of phenol was suppressed by the sulfide ion at a concentration comparable to or larger than that of phenol.

A cation exchange membrane carrying N -(8-quinolyl)-sulfonamide was prepared by attaching the chelating reagent to side chains of a polymer. The chelating reagent was known to have selectivity for Cu 2+ over Fe 3+ . Acrylic acid was also introduced to add a hydrophilic property. All compounds were identified by mp, elemental analyses, IR, 1 H NMR, 13 C NMR and GC-MS. The ratio of the chelation monomer to the acrylic acid was varied between 1:7 and 1:1. The molecular weight of the prepared polymer, determined by gel permeation chromatography, was between 5×10 5 and 10 7 . The above polymer diluted with Me 2 SO was impregnated into a porous Teflon membrane and then the solvent was evaporated. The membrane had enough hydrophilicity even after the above operation. The membrane was sandwiched between 2 glass cells filled with a Cu 2+ and Fe 3+ mixture solution at a pH of 2.0 (extraction side) and with 1 N sulfuric acid (stripping side), respectively. The apparent diffusion coefficient of Cu 2+ through the present membrane was almost comparable or a little smaller than that of the commerical one, while that of Fe 3+ was suppressed remarkably. Thus, the selectivity of Cu 2+ over Fe 3+ became 2.6, i.e., ca. double that of the commercial membrane.

Afforestation on a large scale has a possibility to be a countermeasure against the global carbon dioxide problem. There are, however, many problems that should be solved. In the present paper, the importance of systems approach of greening is emphasized and discussed. The systems adopted here are the system of land utilization, social and industrial, and energy supply as well as the estimation method of energy balance. And also several technological problems are discussed in terms of construction of ecological model and simulation of artificial rainfall for water.

The surface plant is thought to be one of the most feasible final sinks. In the present paper, its role in the carbon cycle is summarized, and significance, scale and advantage of greening of arid and semiarid lands in the carbon dioxide problem are demonstrated. We also present the methodology of the evaluation of the effects of the greening on the problem, considering both the energy input and the amount of fixed carbon.

Various chemical and biological processes have so far been proposed for carbon dioxide recovery, conversion into organic matter and reutilization, which is called the carbon recycling system. In this paper, their evaluation strategies are discussed. They are classified into two categories; with and without energy which is utilized artificially. It is clarified that most of the chemical and biological carbon dioxide fixation systems or carbon recycling systems with artificial energy should be evaluated from the energy point of view as primary and secondary energy systems, and comparing them with other alternative soft energy paths so far proposed. Chemical and biological processes which should be evaluated separately from new soft energy paths are only those which essentially require no artificial energy, such as afforestation of deserts, fertilization to ocean and utilization of rock weathering reaction.

We evaluated the energy balance of an ocean thermal energy conversion (OTEC) system that is one of the substitute energy sources. It was found that a 100 MW OTEC system reduces the amount of CO 2 emission by 140,000 t-C/year, as compared with a 100 MW coal fired power plant. Its energy pay back time was calculated to be 0.46 year. In addition, the synergistic CO 2 uptake effect by the compulsory circulation of the ocean was calculated to be 7,800 t-C/year for a 100 MW OTEC system on the basis of the difference between the present and pre-industrial CO 2 concentrations in the atmosphere.

The effects of gasification conditions, namely bed temperature, static bed height, and nozzle diameter, on the concentrations of H 2 , CO, and CO 2 were investigated using a batchwise fluidized bed gasifier of coal char. Gas concentration profiles in the bed could be explained by the production of gases chiefly via combustion, steam gasification, CO 2 gasification, and the diffusion of produced gases. The temperature dependence of gas concentrations indicates that steam gasification occurred in the lower part of the grid zone at a higher bed temperature and the selectivity of CO production via combustion in the boundary region of the jet and annulus also increased. The results of the effect of static bed height suggest that CO 2 gasification mainly proceeded in the bubbling zone and the local reactions in the grid zone were hardly influenced by gas and solid behavior or reactions in the upper part of the bed. Though the diameter and height of the jet would be dependent on nozzle diameter, the effect of nozzle diameter on the local progress of gasification in the grid zone was hardly observed. It can be concluded that gasification proceeded in both the bubbling zone and annulus region, especially near the distributor, while combustion mainly occurred in the jet and boundary of the jet and annulus.

気流層およびアルミナ粒子を媒体とする粉粒流動層を用いてケイソウ土の焼成を行いプロセスの可能性を探求した.焼成には空気を用いた.窒素気流中でケイソウ土を焼成すると黒く変色したことから焼成には酸素が必要であることが確認された.強熱減量 (L.O.I.) に対する焼成温度および滞留時間の影響を流動層を用いて検討したところ, 1173K40分で十分焼成されることがわかった.気流層を用いてL.O.I.に対する操作条件の影響を検討したところ, 層温度および滞留時間の影響が最も顕著にみられた.1473Kの高温ではケイソウ土の焼成にはほとんど数秒で十分なことがわかった.気流層焼成品は, 焼成工程においては造粒は生じておらず, またろ過試験の結果より, 本焼成プロセスでは焼成後の粉砕工程が不要なためケイソウ土のシェルが破壊されていないことが示唆された.このことからさらに低品位な原料の使用が可能と思われる.

Sequestered carbon by afforestation should be evaluated according to the methodology decided by UNFCCC. In this study, according to this methodology, estimation results of carbon mitigation potential of arid land afforestation in Western Australia were reported. This study consist of tree census of afforestation sites and natural vegetation, exploration of appropriate afforestation candidate area using satellite image analysis and calculation of carbon mitigation potential. Evaluated sequestered carbon amount was compared to the total CO 2 emission of Japan and Australia.

We developed a fluidized bed-chemical vapor deposition (CVD) reactor for a novel method of particle processing, such as particle coating and surface treatment. Microwave plasma was applied as an excitation source of reactive gases, and alumina and silicon were used as bed materials. The hydrodynamic behavior of the plasma-bubbling fluidized bed was studied and the field of plasma generation was investigated optically. Only minor plasma generation was noted in the dense phase. Plasma emission was observed in most of the bubbles in the alumina-fluidized bed, while plasma generated at the surface of the silicon-fluidized bed where bubbles splashed. Methane conversion was carried out in the alumina-fluidized bed as a model reaction. Although excitation of methane occurred in bubbles, excited species entered into the dense phase from bubbles and were effectively converted to carbon on the surface of the particles. Thus, heterogenous CVD on the surface of particles may occur in this reactor.

The effect of adding a water-soluble chelating agent, diethylenetriaminepentaacetic acid (DTPA), to the feed phase was studied on the selective permeation of rare earth metal ions (Ln3+) through a supported liquid membrane (SLM) containing 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (PC-88A). High selectivity of Pr to Nd was observed at a pH of 2.0 in the stripping phase, and selective permeation of La was observed at higher pH values. The permeation mechanism of the Ln3+ was analyzed, and the above results were explained by the change in the concentrations of free Ln3+ in the feed phase and Ln3+/PC-88A complexes in the SLM with pH. On a etudie l'effet de l'ajout dans la phase d'alimentation, d'un agent de chelation soluble dans l'eau, l'acide diethylenetriaminepentaacetique (DTPA), sur la permeation d'ions metalliques de terres rares (Ln3+) dans une membrane liquide supportee (SLM) contenant du mono-2-ethylhexyl ester de 2-ethylhexil acide phosphorique (PC-88A). On a observe une grande selectivite de Pr vers Nd a un pH de 2,0 dans la phase d'extraction, et une permeation selective de La a ete notee pour des valeurs de pH plus grandes. On a analyse le processus de permeation de Ln3+, et les resultats ci-dessus ont ete expliques par le changement dans les concentrations en Ln3+ libres dans la phase d'alimentation et en complexes Ln3+/PC-88A dans la SLM avec le pH.

連続式ジェッティング流動層ガス化炉 (内径, 78.1mm) を用いて, 太平洋炭乾留チャーのガス化を行った.グリッド部と呼ばれるガス送入部付近のガス濃度分布を実測し, 燃焼・ガス化反応の相対的寄与を検討した.このとき, グリッド部での複雑な温度分布による影響を解消するため, 乾留チャーをアルミナで, ノズルより送入した空気を窒素で希釈した.ジェット内では燃焼が, アニュラス部では水性ガス化反応がそれぞれ支配的であった、ジェット-アニュラス間のガス交換速度は速く, 温度の影響をほとんど受けなかったことから, グリッド部の濃度分布はガス化速度の違いによると推測した.さらに, 既報のバッチ式ガス化炉 (内径43.0mm) における実験結果との比較から, スケール効果についても言及した.塔径を変えたとき, ジェット内ではほとんど同じガス濃度を示したが, アニュラス部での生成ガス濃度は顕著な違いがみられた.

Local behavior of gas and particles in a three-dimensional jetting fluidized bed grid zone was investigated. A cone-shaped distributor with a center nozzle was employed as a gas injector and the results were compared with those for a flat distributor. A semicylindrical column was used to observe the phenomena in the grid zone from the transparent flat wall by video camera. An optical fiber probe measurement was also conducted simultaneously. The signals obtained by the sensor were compared with pictures from the video recorder and correlations between the phenomena and the signals were elucidated. Periodic effusion of particles from the annulus into the jet were apparently caused by jet constriction with the same frequency. The optical fiber probe measurement method was applied to a three-dimensional cylindrical bed. The effects of gas velocity, nozzle diameter, shape of the gas distributor on jet shape, jet constriction frequency and bubble frequency were discussed. It was suggested that the momentum of gas introduced from the nozzle should be able to be used to estimate the jet diameter and the jet height. It was also found that the jet shape was drastically affected by the shape of gas distributor. The jet constriction frequency was found to increase with gas flow rate from the nozzle.

Vapor-phase oxidative acetoxylation of toluene on Pd-based bimetallic catalysts was investigated. The main products were benzylacetate, produced via side-chain acetoxylation, and CO and CO2 resulted from combustion. Nuclear acetoxylation hardly occurred. A K-doped Pd-Au/SiO2 gave the highest activity and selectivity for synthesis of benzylacetate among the catalysts tested; the yield of benzylacetate on the K-doped Pd-Au/SiO2 was about 150 times greater than that on a Pd/SiO2. It was found that the addition of an adequate amount of Au to Pd/SiO2 inhibited the formation of CO2, and that potassium species worked as sites for adsorption and activation of acetic acid.

微粉炭燃焼灰層にpH=3, 5, 7, 11の緩衝溶液を連続的に透過させ, 灰中に微量含有されている有害金属元素であるAs, Mo, Pb, Vおよび溶出液にアルカリ性を付与するMg, Caを対象として溶出挙動を検討した.対象としたほとんどの元素において, 実験開始1時間後までは急速な溶出がみられたが, その後はわずかな溶出にとどまった.これは石炭灰中の各元素の形態 (化物種) により, 溶出が容易な部分と困難な部分の存在を示唆している.溶出率はXt/ (1+Yt) なる時間tの関数で定式化することができた.なお, この式でXは初期最大溶出速度を, X/rは最大溶出率を表す.すべての元素において初期最大溶出速度および最大溶出率は, 浸出液のpHが低くなるにつれ大きくなった.なかでも, pHによらずAs, Moは高い溶出率を示した.Asなどの揮発性の高い元素は, 石炭の燃焼過程において灰表面に凝集するため, 容易に溶出すると考えられる.また, 初期溶出速度と最大溶出率に相関関係がみられた.

様々な灰分含有率を有する石炭粉を造粒, 乾留後燃焼させ, 石炭中の微量元素を含む27元素の灰中への残留率をICP発光を用いて測定した.一部の元素については高温での揮散がみられた.生成した灰を粉砕あるいは粉化し, 純水あるいは酸性水への種々の元素の溶出性を測定した.検出されたほとんどの元素について, 石炭粒燃焼時の粒子内最高温度とともに溶出性が抑制される傾向がみられ, また一部の元素についてはある温度以上での急激な溶出性の減少がみられた.溶出性は灰のガラス化により抑制されるものと考えられた.

Local concentrations of gases in the jetting fluidized bed coal gasifier, particularly in the grid zone of the bed were measured to discuss gas exchange between the jet and annulus and local progress of chemical reactions. Air was introduced from the gas injection nozzle and steam was introduced from the coneshaped distributor plate. Gas exchange between the annulus and the jet rapidly occurred. Compared with the case that only steam was introduced, it was found that air introduced from the nozzle produced carbon oxides at around the boundary of the jet and as a result decreased the rate of steam gasification in the annulus. Both for physical and chemical phenomena the grid zone cannot be regarded as uniform. The grid structure strongly influenced the performance of the gasifier.

Temperature at the center of burning char particles was measured. Effects of the temperature and coal properties on behavior of minerals in the coal ash with vitrification and sintering of the ash were discussed. The maximum temperature inside the burning char particle was 20–400 K higher than the surrounding temperature. For the coals with relatively low melting points of ash, the maximum temperature almost linearly decreased with the increased surrounding temperature, while for the coals with relatively high melting points of ash, the temperature increment was almost kept at 200–300 K. For all coals, the temperature increment reached to zero above 1623 K. Quartz peak intensity measured by X-ray diffraction decreased with the maximum temperature and the peak disappeared by vitrification of ash, at about 1673 K irrespective of its melting properties. Effects of the vitrification on leachability of various elements in ash were also discussed.

A model for coal gasifiers was proposed from the combination of the KuniiLevenspiel bubbling bed model and our own grid zone model. Based on the model, local contribution of individual reaction was analyzed and local concentration profile was predicted in the grid and bubbling zones of a laboratory scale fluidized coal gasifier. The effects of lateral temperature and bed height on CO, H 2 and CO 2 concentration were discussed by comparison with experimental results. The results showed that the numerical predictions are corresponding to the experimental ones. It has been verified that combustion occurs mainly nearby the jet region, steam gasification both in the annulus and emulsion regions and CO 2 gasification mainly in the emulsion region. It is clearly shown that the contribution of the progress of the reactions in the grid zone to total gasification performance is high.

Gasification of sawdust was conducted using an experimental fluidized bed with inert particles under the differential and stable condition, by feeding the dried sawdust particles. The gas production rates were measured under the conditions with steam, f c ′ and without steam, f c , [molC/s]. The overall gasification reaction rate constant, k [1/s], was determined from the difference in production rate of gaseous carbon between the conditions with steam and without steam [g-C/s], divided by weight of carbon in bed for various partial pressures of steam, P H2O , and temperatures, T [K]. By the present method, the rate was measured under the actual condition of fluidized bed biomass gasifiers; rapid carbonization of sawdust, and simultaneous pyrolysis and gasification. The rate was given as a function of T and P H2O . Finally, the observed overall rate constant in the bed was related with the dynamic change in rate constant with the progress in conversion of char, which are usually obtained by batchwise experiments, such as TGA.

海洋を利用する二酸化炭素による地球温暖化問題の対策技術の一つとして施肥法がある。海洋に窒素, リンなどの栄養塩を添加することにより植物プランクトンの増殖を促進させ, 海洋表層の二酸化炭素分圧, ひいては大気中の二酸化炭素量を減少させるとのものである。本報では本対策を工学的に評価するために, 物質収支的考察, 海洋の炭素循環に基づく時間的応答と海洋中各炭素濃度への影響の考察, 肥料製造工程までを含めたエネルギー的評価, 検討を逐次行った.海洋プランクトン中のPNC比に基づき必要肥料量と撒き方を決め, そのときの応答を有機・無機炭素と窒素の非定常循環および光合成による炭素固定を組み入れたBoxモデルにより検討した。その結果, 本法は2, 3年の内に顕著な効果が現れるが, 一方表層の有機物量は百年間施肥をしても, 現在の貧栄養状態下での濃度の2倍程度となるにすぎない.肥料製造工程, 輸送までを含めたエネルギー的評価を行ったが, この過程でのエネルギー使用により放出される二酸化炭素量は施肥により海洋に取り込まれる二酸化炭素量の9%程度である。

The effect of the addition of diethylenetriaminepentaacetic acid(DTPA) to the stripping phase on the kinetics of permeation of rare earth metal ions, La"-, Pr3+ and Nd3+, through a supported liquid membrane (SLM) containing 2-ethylhexyl hydrogen 2-ethylhexylphosptionate (PC-88 A) was investigated. The flux of Ln3+ steeply decreased with increasing pH in the stripping phase (pHs) and was not detectable above pH 3.0 in the absence of DTPA. On the other hand, in the presence of DTPA, it is worth noting that Ln3+ permeated through the SLM even in the range of pH, where the permeation of Ln3+ was not detractable without DTPA, and that flux remained almost constant between pH, of 1.4 and 3.3. Experimental results on the flux under the various conditions of stirring speeds, pH of feed phase, DTPA concentrations and SLM thickness, led to the assumption that the permeation rate was controlled by the diffusion of Ln complexes in SLM with the concentrations of equilibrium at the extraction interface and zero at the stripping interface. The calculated rates and the average concentrations of Ln in SLM under the above assumption were well coincided with the experimental results, which supports the proposed mechanism. It is also suggested that increasing concentrations of dissociated DTPA species should cause to form complexes with Ln3+ to compensate the decrease in proton activity in the stripping phase with increasing pH.579

Oxidative acetoxylation of toluene and benzene using molecular oxygen was carried out over supported palladium catalysts in the temperature range of 453-493K at atmospheric pressure. It was found that the addition of gold on silica-supported palladium promoted acetoxylation of toluene and benzene.

Permeation rates of L-methionine and acethyl-DL-methionine were measured through ion exchange membranes into sodium chloride solution, assuming that the former was produced from the latter using a immobilized enzyme reactor. Both were permeated through an anion exchange membrane. L-methionine was selectively recovered from a L-methionine and acethyl-DL-methionine mixture by Donnan dialysis using a cation exchange membrane under the various pH conditions, however its rate was smaller than that through anion exchange membrane.At low pH, the permeation of hydrogen ion was dominant while that of L-methionine was suppressed. The flux of L-methionine attained to a maximum at pH 2 and decreased with increasing pH. Its mechanism was discussed based on ion exchange equilibrium at the interface and mass transfer in the boundary layer and membrane.

Fluidized bed grid zone model and Kunii-Levenspiel bubbling bed model were combined and applied to fluidized bed coal gasification. In the model, local gas compositions in the grid zone were predicted and compared with our experimental results. The effects of the operational conditions on local reactions were also discussed.

Methane conversion was carried out at atmospheric pressure in a d.c. plasma jetting fluidized bed reactor in order to elucidate fundamental characteristics of this reactor. Particle circulation between the annulus and the jet enhanced gas mixing. It was confirmed that heterogeneous carbon deposition occurred on the surface of particles in and around the plasma. Particle coating processes using plasma-enhanced CVD was expected to be realized.

流動層CVD法によりモノシランから製造した多結晶シリコン粒子には残留水素が含まれ, CZ引き上げ工程においてるつぼ内の流動を乱し, 問題となることが知られている.本研究では熱処理による多結晶シリコン粒子からの残留水素の脱離を行った.水素脱離の活性化エネルギーを昇温脱離 (TPD) 法により求めた.FTIRによる測定から, 多結晶シリコン粒子中には種々のSi-H結合が存在することが明らかになった.吸収ピーク面積は, TPDによる水素の脱離量の増大とともに小さくなった.この関係から, 残留水素量は反応したモノシランの中に存在していた水素の約0.05%に相当することがわかった.また加熱処理によるFTIRの吸収ピーク面積の減少とともに, シリコン粒子の粒子密度は直線的に増大し, ほほ真密度にまで至ることがわかった.

5～20μm程度の窒化珪素微粒子を核として, この上にサブミクロンシリコン微粉をコーティングすることを試みた.主たる目的は反応焼結時の焼結性改善である.アルゴンで希釈したモノシラン気流中に窒化珪素の核粒子を均一にかつ希薄に浮遊させ, 核粒子よりなる流動層からCVD反応器に送入した.さらに附加ガスとしてアルゴンを反応器底部周囲から反応器に送入した.生成粒子の流通抵抗は生成粒子中のシリコン微粉量に比例した.SEM, TEMの結果から, 核粒子は, 一次粒子径約0.01μmのシリコン超微粉により覆われていることがわかった.XRDのチャートにはシリコン微粉の弱いパターンが窒化珪素のパターン上に現われていることが観測された.一方附加ガスを流入しない場合には核粒子は密な析出物で覆われ, またXRDチャートはブロードとなり, シリコンのパターンも見られなかった.附加ガスの送入により核粒子上へのシリコンの異相析出が抑えられた.これは附加ガスを装置内で加熱し反応ガスと混合することにより均相反応が生じる一方その導入により反応器内の滞留時間が短くなり異相析出反応が抑えられたからと思われる.

The travel path of the gases in the coke oven has always been of interest. However, few studies have been reported. In the present investigation, the time variations of flow direction and flow resistance of the produced gas in the coal and coke layers were measured in an experimental one-dimensional carbonization apparatus simulating a commercial coke oven.The coal packed in a quartz tube was heated from one side simulating the wall side of a commercial coke oven at a constant heating rate and then kept at constant temperature (1274 K). The other side corresponding to the center side of the commercial coke oven entered into the furnace lastly. The first series of runs were conducted by opening both sides of the tube. Most of the produced gas was evolved from the wall side except the last stage of t he carbonization. Small increase in the wall side pressure caused the drastic increase in the evolution rate from the center side at the first and latter middle stages. However, at the earlier middle stage of carbonization, most of the gas was evolved from the wall side even under this condition. In the second series of runs, one side of the tube was closed. The steep increase in the wall side pressure and the interruption of gas evolution were observed at the earlier middle stage of the carbonization, only when the wall side was closed. In the last series of runs, nitrogen was forcedly introduced through a thin layer from one side. Steep pressure increase was randomly observed when the layer was at around 773 K, irrespective of the flow direction of the nitrogen. In conclusion, at the earlier middle stage of the carbonization, a plastic zone at around 773 K existed between the main gas production zone and the end of the center side and the flow resistance of the zone was found to be large.

The travel path of produced gas in a coke oven has always been of interest. However, few studies have been reported on this subject. In the present study, a tracer technique was employed for the determination of the path of gas in a test coke oven with width of 45 cm, and charge height of 85 cm. Three tubes were inserted horizontally from the coke side at 15.6 cm high (L) and at 0, 8 and 16 cm from the center of the width. Two kinds of tracer gas were uniformly introudced along the tubes. Other six tubes were also inserted at 36 (M) and 54 (H) cm high and at 0, 8 and 22 cm from the center, and the gas in the oven was withdrawn from their ends located at the center of the length of the oven. The gas sampling was conducted every two hours through the sampling tubes and from the exit ascension pipe, where the total flow rate of the produced gas was determined from the concentrations of tracers. Ar injected at "L16" was hardly detected inside the charge (0 or 8 cm from the center) at the middle stage of carbonization. The flow rate of produced gas at the vicinity of the wall (22 cm from the center) was determined from mass balance of Ar assuming that all Ar flowed there. Rates of gas cross from the center side to the wall side was evaluated from the concentration profile of He introduced into the coal layer. At the middle stage, most of the produced gas passed upward in the coke layer and no cross flow was found. This phenomena were to be explained by large flow resistance of the plastic zone. At the last stage, both of the tracers were uniformly distributed all over the coke layer.

Network coordinates (NCs) construct a logical space which enables efficient and accurate estimation of network latency. Although many researchers have proposed NCbased strategies to reduce the lookup latency of distributed hash tables (DHTs), these strategies are limited in the improvement of the lookup latency; the nearest node to which a query should be forwarded is not always included in the consideration scope of a node. This is because conventional DHTs assign node IDs independent of the underlying physical network. In this paper, we propose an NC-based method of constructing a topology-aware DHT by Proximity Identifier Selection strategy (PIS/NC). PIS/NC assigns an ID to each node based on NC of the node. This paper presents Canary, a PIS/NC-based CAN whose d-dimensional logical space corresponds to that of Vivaldi. Our simulation results suggest that PIS/NC has the possibility of dramatically improving the lookup latency of DHTs. Whereas DHash++ is only able to reduce the median lookup latency by 15% of the original Chord, Canary reduces it by 70% of the original CAN.

As demand for high fidelity multimedia content has soared, content distribution has emerged as a critical application. Large multimedia files require effective content distribution services such as content distribution networks (CDNs). A recent trend in CDN development is the use of peer-to-peer (P2P) techniques to enhance scalability, fault resilience, and cost-effectiveness. Unfortunately, P2Pbased content distribution poses a crucial problem in that update propagation is quite difficult to accomplish. This is because peers cannot obtain a global view of replica locations on the network. In this paper, we propose speculative update, which quickly propagates an update to all replicas in a pure P2P fashion. Each server attempts to determine the directions in which there will be replicas with high probability based on server’s local state used for replica repositioning. Then, it relays update messages speculatively in those directions. Simulation results demonstrate that our mechanism propagates an update to all replicas faster than the current pure P2P-based approaches.

局所的ガスおよび粒子の挙動を考慮した流動層グリッドゾーンモデルを開発し, 流動層CVD法によるモノシランからのアルゴン希釈下での多結晶シリコンの製造に応用した.モデルのうち, 粒子およびガスの挙動に関する記述の妥当性について, コールーモデルから得られた粒子速度およびジェット内温度到達度に関する文献値と比較することにより確認した.モノシランの局所熱分解反応速度を考慮にいれ, グリット部におけるモノシランの反応率, 微粉生成速度およびクロッキングの可能性についてシミュレーションを行い, 計算結果を従来得られている実験結果と比較した.全微粉生成量に対するグリッド部の寄与は無視できるほど小さく, 微粉は主に流動層上部の気泡領域で生成していると予測された.クロッキングの可能性を表す指標として, 反応速度に対するシリコン粒子の移動速度を相対的反応速度と定義し, 計算したところクロッキングの可能性に対するガス流速, 層温度, シラン濃度およびガス送入口形状の影響についての計算結果は実験結果と定性的によく一致した.

The optimum operation temperature of coal gasifier is considered to be about 1300°C from various view points. In the present study, the temperature profiles in a batch experimental fluidized bed coal gasifier were measured. Flat and cone shaped gas distributors for steam introduction with 3mm and 6mm i.d. nozzles for air introduction were employed. The effects of the grid structure on the tempera-ture profile in the grid zone and on the produced gas composition from the experimental gasifier were discussed.An obvious jet-shape and restricted high temperature area was observed without any clinkers, when air was introduced from a nozzle with small diameter (3mm i.d.) and steam from cone type distributor, while the high temperature area spread over the cross sectional area of the bed when the air was introduced from 6mm i.d. nozzle and steam from flat plate. The consumption rate of carbon and the evolution rate of carbon monoxide were extremely high and the production of carbon dioxide was suppressed at relatively low conversion in the former case while the increases in the combustion rate of produced hydrogen and the ratio of production of carbon dioxide to that of carbon dioxide were observed in the latter case. The relatively high temperature operation with favorable produced gas composition was suggested to be possible by employment of suitable grid structure to increase the circulation rate of carbon.