화학공학소재연구정보센터
Energy & Fuels, Vol.32, No.11, 11538-11546, 2018
Characterization of Hydrochar Pellets from Hydrothermal Carbonization of Agricultural Residues
In this work, the effects of operating conditions of hydrothermal carbonization on the hydrochar pelletization and combustion characteristics were investigated. Corn stalk was carbonized under different conditions and then pelletized to obtain the hydrochar pellets. It was found that hydrothermal temperature and residence time greatly affect the pellet quality. When the temperature was raised up to 240 degrees C with the residence time longer than 60 min, the heating values of hydrochar were close to or even higher than those of lignite. After hydrothermal treatment, 73.71-94.71% K and 91.81-94.32% Cl contained in the feedstock were removed, indicating a low fouling and slagging tendency when the pellets are used in combustion. The compressive strength and durability increased first with increasing temperature and then decreased with further increasing the temperature from 240 to 300 degrees C. The influence of residence time showed a similar trend, and the compressive strength and durability reached its maximum value at the temperature of 240 degrees C and residence time of 60 min. The hydrophobicity of the hydrochar pellets increased with increasing the temperature and residence time. Hydrochar pellets obtained at the temperature of 240 degrees C with residence time of 60 min gives the best performance, which can meet the requirement of industrial fuel pellets. Finally, the combustion characteristics were investigated by thermogravimetric analysis, and the results indicated that hydrochar pellets were combusted in a comparatively mild way with a high thermal efficiency. As a general conclusion, the hydrochar pellets have much better qualities than the raw corn stalk, facilitating the transportation, long-term storage, and combustion application.