著者

伊東 弘行

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.852, pp.17-00080-17-00080, 2017 (Released:2017-08-25)

参考文献数

30

被引用文献数

5

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To investigate the influence of briquette size and density on the combustion behavior in both flaming and char combustion stage, the combustion experiments with the highly densified columnar briquette made from cypress sawdust were carried out. Three sizes of the briquette, φ30 mm×60 mm, φ35 mm×70 mm and φ40 mm×80 mm, of which diameter/length ratio is kept constant at 1/2 and three types of the briquette density, 900, 1100 and 1300 kg/m3 were employed. The water content of the briquette was kept around 10 wt%. The mass loss rate and the duration in both combustion stages were measured. In the flaming combustion stage, it is observed that the average mass loss rate per unit specific surface area is proportional to the briquette surface area, while it doesn't depend on the briquette density. It is expected by considering Fourier number that the flaming combustion duration is proportional to the product of the inverse square of the specific surface area and the briquette density and it is shown that the experimental results correspond to the expectation. It is found that the relationship between normalized mass loss rate and normalized time is nearly the same regardless of the briquette size and density. In the char combustion stage, normalized mass loss can be approximately expressed with the shrinking core model by assuming the effective oxygen diffusion coefficient in the ash layer for each briquette density used in this study. And it is found that the effective oxygen diffusion coefficient in the ash layer obtained by the shrinking core model decreases with increasing the briquette density.

著者

伊東 弘行 酒井 雄人 井田 民男 藤田 修

出版者

一般社団法人 日本燃焼学会

雑誌

日本燃焼学会誌 (ISSN:13471864)

巻号頁・発行日

vol.53, no.164, pp.63-68, 2011 (Released:2018-01-26)

参考文献数

14

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Utilization of biomass fuel is attracting more attention due to its advantage to the global warming problem. Biocoke (BIC), highly densified biomass briquette, has unique features such as economical advantages for its versatility of biomass resources, high volumetric calorific value because of its high density and high mechanical strength. The BIC made of Reynoutria japonica (Japanese knotweed), cylindrical blocks with 48 mm in diameter and 85 mm in length, are selected in the study. To investigate the fundamental thermal and combustion properties of the BIC, ignition and combustion behaviors are observed in the hot air flow. The results show that the ignition mode and the mass loss rate during the flaming combustion are influenced by the supplied air temperature with an interesting manner. This may be ascribed to the thickness of the heated layer inside the BIC depending on the preheating condition. This is because the heated thickness strongly controls the evolution characteristics of pyrolysis gas and the temperature distribution inside the BIC depends on the distinctive property of the BIC, high density. Finally, a new concept of BIC combustion method is proposed considering the BIC unique physical features as well as its fundamental combustion characteristics.

著者

伊東 弘行 藤田 修

出版者

北海道大学

雑誌

基盤研究(C)

巻号頁・発行日

2008

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カーボンナノチューブ(CNT)を安価に大量に生成できると期待される火炎プラズマを有する燃焼合成法において、直流電場を与えることによりCNT生成が促進される。本研究では、電場印加によるCNT生成場の温度や化学種濃度の変化、生成CNT量および性状への効果を調べるとともに、電気炉中におけるCNT合成に電場を与えCNT成長への電場の効果を調べた。その結果、電場の付与によりCNT成長促進、結晶度の向上が見られ、燃焼合成法における電場付与のCNT合成への効果として、火炎プラズマ移動にともなうCNT捕集増大と金属触媒活性の向上が示唆された。