日本エネルギー学会誌
Online ISSN : 1882-6121
Print ISSN : 0916-8753
93 巻 , 5 号
選択された号の論文の6件中1~6を表示しています
特集:持続可能なエネルギー技術(総説)
特集:持続可能なエネルギー技術(論文)
  • Amirhossein MALAKAHMAD, Witton YEE
    2014 年 93 巻 5 号 p. 505-510
    発行日: 2014年
    公開日: 2014/05/30
    ジャーナル フリー
    Performance of carrier anaerobic baffled reactor (CABR) equipped with polymeric media for energy production and pollution removal from raw palm oil mill effluent (POME) was investigated. Reactor operation was studied in start-up period with no effluent recycled feed and after alkalinity supplementation. Primarily, CABR was fed with diluted POME (COD = 2100 mg/L and OLR = 0.53 g-COD/(L d ) which was then increased gradually to actual concentration (COD = 52,500 mg/L and OLR = 13.13 g-COD/(L d)). The volumetric methane production and methane yield were reached to 2.3 L-CH4/(L d) and 0.25 L-CH4/g-COD removed, respectively at the end of start-up period. The biogas was containing 75 - 54 % methane. pH profile and stability of volatile fatty acids (VFA) concentration in CABR effluent indicate that anaerobic system is active in the reactor throughout the study. Use of methanogen-enriched inocula and appropriate separation of acidogens and methanogens in CABR were the reasons for satisfactory performances of the anaerobic system.
  • Naoki TOYAMA, Tetsuo UMEGAKI, Qiang XU, Yoshiyuki KOJIMA
    2014 年 93 巻 5 号 p. 511-516
    発行日: 2014年
    公開日: 2014/05/30
    ジャーナル フリー
    The influence of particle size of hollow silica-alumina composite spheres on their activity for hydrolytic dehydrogenation of ammonia borane (NH3BH3) was investigated. A silica-alumina composite shell was coated onto polystyrene (PS) template particles, before the removal of PS template particle by calcination. The diameter of the PS template particles decreased with an increase in the amount of poly (vinyl pyrrolidone) and the centrifugation speed, and the diameter of the obtained PS template particles was controlled between 150 and 400 nm. Hollow silica-alumina composite spheres with diameters of 180, 230, and 430 nm were prepared using these PS template particles; the shell thickness was controlled 15 nm by adjusting the amount of PS suspension and coating time. The hydrolytic dehydrogenation of NH3BH3 evolved 9.5, 9.0, and 7.0 mL hydrogen in the presence of hollow spheres with diameters of 180, 230, and 430 nm, respectively; the molar ratios of the generated hydrogen to the initial NH3BH3 in the presence of the hollow spheres were 2.5, 2.3, and 1.8, respectively. The results indicate that the activity increases with a decrease in the diameter of hollow spheres.
  • Masami AONO, Hiroshi ABE, Takahiro TAKEKIYO, Yukihiro YOSHIMURA
    2014 年 93 巻 5 号 p. 517-520
    発行日: 2014年
    公開日: 2014/05/30
    ジャーナル フリー
    A room temperature ionic liquid (RTIL), N, N-diethyl-N-methyl-N-2-methoxyethyl ammonium tetrafluoroborate ([DEME][BF4]), shows complicated pH behaviors on a water concentration - time diagram. The RTIL is a hydrophilic property. A strong acidic property was obtained at the water-rich region. On a contrary, at the water poor region, the pH value is around 8. The acid-base property in [DEME][BF4]-water has a relation with the specific aggregations in the liquid. On time-dependent pH measurements, a time-invariant point appears at 60 mol% H2O. Moreover, pH oscillations on the time scale were observed only in the 90 mol% H2O mixture. The oscillation suggests electrochemically unstable two states in the solution. An equilibrium pH value of 90 mol% H2O mixture is approximately 3. After a few days for pH measurements, by-product was formed inside the solution. As a precursor phenomenon of the by-product formation, the pH oscillations might be induced in electrochemically unstable circumstance.
  • Shumpei MURAYAMA, Toshiyuki IWASAKI, Hideki SUGANUMA, Takuya ITO, Shig ...
    2014 年 93 巻 5 号 p. 521-530
    発行日: 2014年
    公開日: 2014/05/30
    ジャーナル フリー
    Biomass has been recognized as a renewable energy source alternative to fossil fuels, because it doesn’t increase CO2 amount in the atmosphere. Among various ways of woody biomass use, IGCC power generation is known as the most possibly efficient technology. In the process, biomass is firstly pyrolyzed and the produced volatile and char are secondary converted; hence it is necessary to know the production process and yields of pyrolysis gas, tar, producing char and char gasification kinetics for effective energy conversion. In this study, many woody biomass species (four softwoods, nine hardwoods and four barks) were pyrolyzed at 1000 °C at the rapid heating rate up to around 1000 °C/s. Then the produced char is gasified in an experimental fluidized bed. After that, the produced char was gasified by CO2 at 1000 °C. We computed char conversion and its rate from CO production rate with time and conversion rate was plotted against conversion. Different gasification rate curves are found for various biomass samples. The gasification rate of char was evaluated by the first order rate constant based on the volume reaction model. Hardwood char gasification rates were faster than those of softwood samples. Most of the gasification rates of char from the bark samples were nearly same as those of woody part samples. As for the hardwood, the char produced from biomass with lower compressive strength generally gave faster reaction rate.
  • Ryunosuke MATSUMOTO, Tsunehiro AKI, Yoshiko OKAMURA, Takahisa TAJIMA, ...
    2014 年 93 巻 5 号 p. 531-535
    発行日: 2014年
    公開日: 2014/05/30
    ジャーナル フリー
    Kelp (Laminaria japonica) was treated in a batch reactor under hydrothermal conditions over a temperature range of 150-190 °C, and the resulting liquid and solid products were analyzed. The effect of salt on the hydrothermal pretreatment of kelp was also investigated. We found that more than 80 % of total organic carbon moved into the liquid phase, leaving only about 10 % in the solid phase. Thus, the effectiveness of the hydrothermal pretreatment on the dissolution of organic compounds was studied. Mannitol, the primary monosaccharide present in kelp, was extracted into the liquid phase; however, the high target temperature resulted in a slight decrease in the yield of mannitol.Formic acid and acetic acid were also produced.The effect of salt was not observed, which indicated the effectiveness of direct treatment of kelp under hydrothermal conditions without the need for desalination.
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