| Abstrakt: |
Corn straw has potential as a biofuel, and is generated in large amounts globally. However, this potential remains underutilized, and torrefaction is one of the processes that can be implemented to improve the energy grade of this biomass. In this study, three process parameters (temperature, heating rate, residence time) were investigated using a response surface method to optimize the torrefaction process of corn straw. At 242.26 °C, a 60 min residence time, and 6.28 °C/min heating rate, the mass yield and higher heating value (HHV) reached their maximum values. Temperature was the most important factor influencing torrefaction, followed by residence time and then heating rate. The gas and liquid by-products were measured by mass spectrometry and mass spectrometry-gas chromatography, and the heat demand of torrefaction was measured by thermogravimetric analysis-differential scanning calorimetry. The HHV of the by-products changed little before 240 °C but increased considerably as the temperature further increased. The HHV at 242 °C was 1,273 kJ/kg. When the heat loss was 50%, 242 °C was the critical point of energy balance, and after that the torrefaction process was energy self-sufficient. These findings provide data to support the establishment of semi-industrial or industrial corn straw torrefaction devices. [ABSTRACT FROM AUTHOR] |
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