Comparative Assessment of the Wet and Dry Torrefaction of Pinus Radiata

ARTEAGA, L.; FLORES, M.; ESCOBAR, M.; SEGURA, C.; GORDON, A.:
Energética 46, diciembre(2015), pp. 5-12.

Abstract

This work compares two thermochemical pretreatments, dry torrefaction and wet torrefaction (or hydrothermal carbonization-HTC), which aims to modify the physical and chemical properties of the wood of Pinus radiata for use as a partial substitute for coal in combustion processes. Parameters assayed in this work were temperature and residence time in the reactor. Dry torrefaction was studied in mild regime (220°C), medium(250°C) and severe (280°C) and exhibited greater energy efficiency (maximum ≈ 90%) than hydrothermal carbonization (maximum ≈ 79.7%): the latter was assayed in a similarrange of temperatures (218 – 300°C). Powder charcoal (bio-carbon) produced by HTC has a higher heating value (HHV of 26.3 MJ/kg) similar to the HHV of a medium-rank coal(29.3 MJ/kg). The assays show that considerable improvements in performance or inthe bio-carbon HHV are not obtained when the HTC process is carried above 255°C and for more than 1 hour. Volatile organic products obtained in each treatment have a similar composition, with a predominance of carboxylic acids, furfurals and sugars.

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