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Munetsuna H.,Hiroshima Institute of Technology | Tamai M.,Hiroshima Institute of Technology | Noda Y.,Toyo Koatsu Co. | Matsumura Y.,Hiroshima University
Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy | Year: 2011

This study was conducted to calculate the energy balance of supercritical water gasification with an activated carbon catalyst for a hydrogen fermentation residue of soybean fiber (SFHFR). To circumvent the problem of plugging, we examined the gasification of SFHFR by a staged operation with alternate feeding of water and feedstock. The calculations were applied to a gasification reaction conducted within a tubular reactor at 600°C and 25 MPa, with an average residence time of 73 s. The calculation results were a cold gas efficiency η r [(amount of energy recovery from feedstock as product gas, Eg) / (energy supply from feedstock, E f)] of 0.72 and an energy efficiency η, Eg / [(heat supplied by the electric furnace, E i) + (energy supply from feedstock, Ef)] of 0.30. A comparison between continuous operation and the operation in staged intervals confirmed the effectiveness of the latter. Source


Munetsuna H.,Hiroshima Institute of Technology | Tamai M.,Hiroshima Institute of Technology | Noda Y.,Toyo Koatsu Co. | Matsumura Y.,Hiroshima University
Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy | Year: 2010

To circumvent the problem of reactor plugging in supercritical water gasification (SCWG), we proposed an SCWG process operated at intervals with a continuous-flow system (10 kg/d) configured to feed water and feedstock in alternate steps. Hydrogen fermentation residues of soybean fiber and restaurant food waste (SFHFR and RWHFR, respectively) were employed as feedstock, and fine activated carbon was used as catalyst. Feedstocks of 2.0-10.0% SFHFR were gasified in a tubular reactor at 600°C, 25 MPa with a residence time of 60-105 s. An 8% concentration SFHSR was gasified with a carbon gasification efficiency of 0.75 without plugging. A 4% RWHFR, a feedstock composed of more diverse substances, was gasified with a carbon gasification efficiency of 0.57. Source


Wada Y.,Chugoku Electric Power Co. | Oyama K.,Chugoku Electric Power Co. | Yamasaki T.,Chugoku Electric Power Co. | Uchiyama I.,Chugoku Electric Power Co. | And 6 more authors.
Nihon Enerugi Gakkaishi/Journal of the Japan Institute of Energy | Year: 2013

The operation of a 1 t-wet/d supercritical water gasification plant was evaluated for the gasification of barley shochu residues with activated carbon charges ranging from 0 to 0.05 kg/kg-slurry. Activated carbon concentrations greater than 0.025 kg/kg-slurry were found to prevent plugging by tarry residues. The pressure loss for the effluent that flowed in the annulus of the double-tube heat exchanger did not exceed 0.2 MPa. Long continuous operation times of 17 h 48 min were possible with an activated carbon charge of 0.025 kg/kg-slurry. Activated carbon is not only effective for prevention of plugging, but also effective for reduction in total organic carbon and enhancement of carbon gasification efficiency. An economic evaluation showed that the process can be viable when operated for more than 200 d per year. Source


Matsumura Y.,Hiroshima University | Hara S.,Hiroshima University | Kaminaka K.,Hiroshima University | Yamashita Y.,Hiroshima University | And 6 more authors.
Journal of the Japan Petroleum Institute | Year: 2013

Supercritical water gasification is expected to be an effective gasification process for wet biomass, but its reaction kinetics has not been elucidated for actual biomass feedstocks. In this study, seven biomass species are gasified in a supercritical water gasification reactor with and without use of a suspended activated carbon catalyst, and the overall gasification rates are determined. The feedstocks can be classified into three groups depending on the gasification characteristics. Representative gasification-rate parameters are presented. The homogeneous reaction had a pre-exponential factor of 50.0 s -1 and an activation energy of 67.9 kJ/mol. The heterogeneous reaction for feedstocks with high cellulose content had a pre-exponential factor of 4.87×109 s-1 and an activation energy of 161 kJ/mol, while, feedstocks with low cellulose content had a pre-exponential factor of 1.91× 104 s-1 and an activation energy of 84.2 kJ/mol. Source


Matsumura Y.,Hiroshima University | Yamashita Y.,Hiroshima University | Inoue S.,Hiroshima University | Kawai Y.,Chuden Plant Co. | And 3 more authors.
10AIChE - 2010 AIChE Annual Meeting, Conference Proceedings | Year: 2010

Supercritical water gasification is a promising technology for the effective use of wet biomass including manures, food wastes, and sewage sludge. The authors have shown that the reaction kinetics in supercritical water gasification with and without activated carbon catalyst can be experessed using Arrhenius type first-order reaction rate. In this study, the reaction paremeters for various biomass species including chicken manure, swine manure, cattle maure, soy-bean hydrogen fermentation residue, food waste hydorgen fermentation residue, waste grass, and seaweed ethanol fermentation residue were determined, and compared. The result showed that the bioamss species can be categorized into some groups in terms of its reactivity in supercritical water and the effect of activated carbon catalyst. Source

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