遠赤外線加熱を付加した過熱水蒸気処理によるバイオマスの炭化速度に及ぼす試料サイズの影響 <原著論文>

Size Effect of Biomass on Carbonization Rate Treated in Superheated Steam Combined with Far Infrared Heating

伊佐 亜希子

羽倉 義雄

鈴木 寛一

日本食品工学会誌

Bamboo powder (particle size 0.2 mm) and three cube-shaped woods (1 mm, 2 mm and 3 mm) were carbonized in the superheated steam (SHS) combined with far infrared heating (FIH), and the effect of sample size on carbonization rate was investigated. Carbonization temperature was adjusted at 270, 280, 290, and 300°C by regulating the SHS temperature at 180°C with the FIH temperatures at 375, 400, 425, and 450°C. Carbonization energies for the combined treatment were also compared with those for the carbonization treatment in SHS alone at 255, 265, 275, and 285°C. The generation rate of the SHS was the same for both carbonization treatments. The carbonization rate of each sample obeyed a first order reaction rate equation. Average values of the activation energy for the combined treatment of SHS with FIH and for the treatment in SHS alone were 137 kJ/mol and 149 kJ/mol, respectively. These values were almost the same as the activation energies for thermal decomposition of starch and cellulose under nitrogen gas. The relationship between the logarithmic values of the sample sizes and those of the carbonization rate constants was expressed as a linear curve at each carbonization temperature. Compared with the carbonization in the SHS alone, the combine treatment of SHS and FIH was much easier to make the carbonization apparatus in high carbonization temperature conditions with small additional heat. The higher the FIH temperature, the smaller the carbonization energy was obtained, because of shortening the carbonization time significantly.

竹粉(粒径0.2mm)および試料サイズを1mm, 2mm, 3mm角に揃えた木片を遠赤外線加熱(FIH)を付加した過熱水蒸気(SHS)処理で炭化処理し, 試料サイズの違いが炭化速度に及ぼす影響について調べた. SHS温度180℃にFIH温度375, 400, 425, 450℃を付加して, 炭化温度を270, 280, 290, 300℃に調整した. また, SHS温度255, 265, 275, 285℃のSHS単独処理の場合とFIH付加に要する炭化エネルギを比較した. 2つの炭化処理で過熱水蒸気生成速度は同じとした.

炭化速度は, どの試料においても一次反応速度式に従った. 活性化エネルギの平均値は, 遠赤外線加熱を付加した過熱水蒸気処理の場合は137kJ/mol, 過熱水蒸気単独処理の場合は149kJ/molであった. これらの値は, 窒素ガス中での澱粉やセルロースの熱分解反応の活性化エネルギの文献値とほぼ一致した. 試料サイズと炭化速度定数の関係は, いずれの炭化温度でも両対数紙上で直線で表された. SHS処理にFIHを付加した場合には, SHS単独処理の場合と比較してわずかな熱量の付加で炭化装置を高温条件にすることが容易であり, 遠赤外線ヒータの温度を高温にするほど炭化時間の短縮効果によって炭化に要する熱量は減少した.

superheated steam

far infrared heating

biomass

carbonization rate constant

製造工業 [ 580 ]

日本語

日本食品工学会

[ISSN] 1345-7942

[NCID] AA12076107