Upgrading of woody biomass by torrefaction under pressure

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• 作者：Janewit Wannapeera ; Nakorn Worasuwannarak ; ^{nakorn_w@jgsee.kmutt.ac.th}
• 关键词：Biomass ; Upgrading ; Torrefaction ; Pyrolysis
• 刊名：Journal of Analytical and Applied Pyrolysis
• 出版年：2012
• 期刊代码：46_01652370
• 类别：ch
• 出版时间：July, 2012
• 卷：96
• 期：Complete
• 页码：173-180
• 文件大小：1473 K

摘要

In this study, the upgrading by torrefaction of leucaena, woody biomass, at 200-250 掳C under volumetric pressure up to 4 MPa was examined. It was found that the yield of torrefied leucaena decreased with the increase in torrefaction temperature, whereas at the same temperature the yield of torrefied leucaena increased with the increase in torrefaction pressure. From the elemental analyses, the higher carbon content in torrefied leucaena can be achieved by the rising of torrefaction pressure. As large as 92.6%of carbon was recovered in the torrefied leucaena prepared at 250 掳C and 4 MPa. On the other hand, the oxygen content decreased to 31.1%for the leucaena torrefied at 250 掳C and 4 MPa. The higher heating value (HHV) of leucaena torrefied at high pressure increased significantly when compared to that of leucaena torrefied at atmospheric pressure. As large as 94.3%of energy yield was achieved with the mass yield of 74.4%for the torrefaction at 250 掳C and 4 MPa. From the subsequent pyrolysis and combustion in TGA, leucaena torrefied under pressure showed the difference of weight decreasing curves comparing to that of leucaena torrefied at atmospheric pressure. It was found that the weight of leucaena torrefied at high pressure started to decrease at temperature lower than 200 掳C. The char yield at 800 掳C for the leucaena torrefied at high pressure increased with the increase in torrefaction pressure. These results suggested that the structure of leucaena was changed by the torrefaction under pressure and the cross-linking reactions during the pyrolysis were enhanced by the pressure during the torrefaction resulting in increase in char yields. The substantial increase in char combustion rate was also found for leucaena torrefied under pressure.