Browsing by Author "Yoshiie, Ryo"

Now showing 1 - 6 of 6
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    Contribution of Volatile Interactions during Co-gasification of Biomass with Coal
    (Life science Global, 2013) Kihedu, Joseph H.; Yoshiie, Ryo; Nunome, Yoko; Naruse, Ichiro
    Thermo-gravimetric behavior during steam co-gasification of Japanese cedar and coal was investigated. The difference between co-gasification behavior and the average gasification behavior of cedar and coal indicates two synergetic peaks. The first peak occurred between 300 °C and 550 °C while the second peak was observed above 800 °C. The first peak coincides with volatile release and therefore associated with volatile interactions while the second peak is linked with catalytic effect of alkali and alkaline earth metal (AAEM). Acid washed cellulose and Na rich lignin chemicals were used as artificial biomass components. In reference to Japanese cedar, mixture of cellulose and lignin i.e. simulated biomass, was also investigated. Co-gasification of cellulose with coal and co-gasification of lignin with coal, demonstrates contribution of volatile interactions and AAEM catalysis respectively. Morphology of partially gasified blends, shows hastened pore development and physical cracking on coal particles. Brunauer−Emmett−Teller (BET) surface area of the charred blend was lower than the average surface area for charred biomass and coal.
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    Conversion Synergies during Steam Co-Gasification of Ligno-Cellulosic Simulated Biomass with Coal
    (Scientific Research, 2012-12) Kihedu, Joseph H.; Yoshiie, Ryo; Nunome, Yoko; Ueki, Yasuaki; Naruse, Ichiro
    Lignin and cellulose chemicals were used as artificial biomass components to make-up a simulated biomass. Alkali and Alkaline Earth Metal (AAEM) as well as volatile matter contents in these chemicals were much different from each other. Co-gasification of coal with simulated biomass shows improved conversion characteristics in comparison to the average calculated from separate conversion of coal and simulated biomass. Two conversion synergetic peaks were observed whereby the first peak occurred around 400℃ while the second one occurred above 800℃. Although co-gasification of coal with lignin that has high AAEM content also shows two synergy peaks, the one at higher temperature is dominant. Co-gasification of coal with cellulose shows only a single synergy peak around 400℃ indicating that synergy at low temperature is related with interaction of volatiles. Investigation of morphology changes during gasification of lignin and coal, suggests that their low reactivity is associated with their solid shape maintained even at high temperature.
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    Counter-flow air gasification of woody biomass pellets in the auto-thermal packed bed reactor
    (Sciencedirect, 2014-01) Kihedu, Joseph H.; Yoshiie, Ryo; Nunome, Yoko; Ueki, Yasuaki; Naruse, Ichiro
    Counter-flow packed bed gasification was carried out featuring a combination of downdraft and updraft operation modes. A column reactor of inside diameter 102 mm and 1000 mm height was used. Downdraft and updraft air supply were varied while the total air supply was maintained constant. Counter-flow gasification with downdraft air supply at 12 L/min and updraft air at 4 L/min offered optimal conditions, producing syngas with 4.28 MJ/m3 N LHV and 5.84 g/m3 N tar content. Under similar operating conditions, cold gas efficiency was about 77% while carbon conversion reached 88%. Increasing the updraft air flow resulted in reduced tar generation and increased carbon conversion, however, the syngas LHV and cold gas efficiency were affected adversely.
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    Gasification characteristics of woody biomass in the packed bed reactor
    (Sciencedirect, 2011) Ueki, Yasuaki; Torigoe, Takashi; Ono, Hirofumi; Yoshiie, Ryo; Kihedu, Joseph H.; Naruse, Ichiro
    Gasification technology is recognized as one of the possibilities for utilizing biomass effectively. This study focused on woody biomass gasification fundamentals, using a bench-scale packed-bed reactor. In this experiment, pellets of black pine were gasified, using air as the oxidizing agent. Gasification tests were carried out under both updraft and downdraft conditions. Temperature distributions and compositions of syngas inside the gasifier were continuously monitored during gasification experiments at several ports on the wall of the reactor. The syngas at the exit of the gasifier was also sampled to estimate the amount of tar. Lower heating values of the syngas under updraft and downdraft conditions were 4.8 and 3.8 MJ/m3N, respectively. It was easier to control the height of the packed bed under the downdraft condition than under the updraft condition. Under the updraft condition, a bridging phenomenon occurred. Tar generation under the downdraft condition was lower than that under the updraft condition. This is because tar passes through a partial combustion zone or higher temperature zone in the downdraft gasifier.
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    Performance indicators for air and air–steam auto-thermal updraft gasification of biomass in packed bed reactor
    (Sciencedirect, 2015-08-08) Kihedu, Joseph H.; Yoshiie, Ryo; Naruse, Ichiro
    Auto-thermal updraft gasification of biomass pellets in a packed bed reactor was conducted by using air and air–steam mixture. Air–steam gasification produced syngas with slightly improved lower heating value of 4.5 MJ/mN3 in comparison to 4.4 MJ/mN3 produced during air gasification. The corresponding tar generation for air gasification and air–steam gasification was 21.2 g/mN3 and 26.2 g/mN3, respectively. Cold gas efficiency for air gasification and air–steam gasification was realized to be 91% and 91.4%, respectively. Carbon conversion during air–steam gasification reached about 91.5% while carbon conversion during air gasification was limited to 84.3%.
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    Reaction Characteristic of Woody Biomass with CO2 and H2O
    (J Stage, 2010) Naruse, Ichiro; Ueki, Yasuaki; Isayama, Tsutomu; Shinba, Takanori; Kihedu, Joseph H.; Yoshiie, Ryo
    Objective in this study is to elucidate the fundamental gasification characteristics for carbonaceous resources. Effects of temperature and gaseous agents on the gasification characteristics of carbonaceous materials were experimentally and theoretically studied by the gasification of woody sawdust, using an electrically heated drop tube furnace. Results of the co-gasification of CO2 with H2O were compared by the gasi- fication by a single gaseous agent such as CO2 or H2O. As a result, H2 and CO concentrations increased with an increase of temperature. CO concentration under the co-gasification condition produced more than that under the single gasification condition. The H2 formation showed the opposite tendency to the CO formation during the co-gasification. This synergy effect was also elucidated theoretically by the simulation of reaction kinetics. The simulated temperature indicating the maximum synergy effect on CO formation agreed well with that obtained by the experiments.