Biomass torrefaction under different oxygen concentrations and its effect on the composition of the solid by-product

Abstract

Torrefaction is a thermal treatment used to improve the properties of biomass in relation to thermochemical processing techniques for energy generation. It is a thermo-chemical treatment method primarily characterized by an operating temperature within the 200-300 ?C range. It is carried out under conditions of atmospheric pressure and in the presence of a minimum amount of oxygen in order to avoid spontaneous combustion. The aim of this study was to evaluate the combined effect of the temperature (240 and 280 ?C) and oxygen concentration (2, 6, 10 and 21%) on the physical and chemical properties of large particles of Eucalyptus grandis. A statistical analysis was carried out. The different oxygen concentrations did not significantly affect the composition of the solid by-product for low temperatures. At 280 ?C, the high oxygen concentration affected some of the properties studied. (Résumé d'auteur

Physicochemical Characterization of Torrefied Wood Biomass under Air as Oxidizing Atmosphere

“…At this temperature, mass losses became more considerable (14% and 20%, see Fig. 2) as a consequence of the thermal degradation of wood constituents (hemicellulose and cellulose) (Rousset et al 2012). Additionally, biomass particle size did not change considerably.…”

“…5a) that could not be compensated by the higher heating value of these materials. Additionally, these samples had higher moisture contents because of the oxidation reactions that could produce water vapor during the torrefaction process (Table 3) (Rousset et al 2012). In contrast, at 180 °C, the biomass FVI tended to increase.…”

“…A reduction of VM content led to a relative increase of fixed carbon (FC) content in the torrefied materials. According to Rousset et al (2012), this release of volatiles is mainly associated with the thermal degradation of hemicellulose at low torrefaction temperatures no matter whether the environment is inert or oxidizing during the torrefaction process. In this work, different results were obtained from those reported by Lu et al (2012), who also studied wood torrefaction under an oxidizing atmosphere.…”

“…Rousset et al (2012) studied the effect of oxygen concentration in the carrier gas on the torrefaction process. Oxygen concentrations were 2 vol %, 6 vol %, 10 vol %, and 21 vol %, with torrefaction temperatures of 240 °C and 280 °C for 1 h of residence time.…”

Torrefaction of Babassu: A Potential Utilization Pathway

“…A programmable PID (proportional-integral-derivative) controller was used to control the temperatures and heating rate of the reactor by way of three thermocouples: one near the electric heater, one inserted through the lid of the reactor, and the last one inside the sample to monitor its temperature, as described in Rousset et al (2012). Finally, two samples were tested in each trial run, one coupled to a precision balance to monitor mass loss and the other to a thermocouple to monitor the internal temperature.…”