Influence of torrefaction on the grindability and reactivity of woody biomass

Abstract

The use of biomass to produce energy is becoming more and more frequent as it helps to achieve a sustainable environmental scenario. However the exploitation of this fuel source does have drawbacks that need to be solved. In this work, the torrefaction of woody biomass (eucalyptus) was studied in order to improve its properties for pulverised systems. The process consists in a heating treatment at moderate temperature (220-300 ºC) under an inert atmosphere. The grindability of raw biomass and the treated samples was compared and an improvement in the grindability characteristics was observed after the torrefaction process. Thermogravimetric analysis of the samples was carried out in order to study their reactivity in air. The DTG curves of the torrefied biomass showed a double peak nature. The kinetic parameters were calculated for each reaction stage. The torrefaction process was found to influence the parameters of the first stage, whereas those corresponding to the second remained unaffected.

Biomass torrefaction: Modeling of volatile and solid product evolution kinetics

“…In Figure 4, model predictions for these quantities are compared with experimental data from Arias et al, 2008;Medic et al, 2011) who measured the initial and final ultimate analyses of torrefied willow, corn stover, and eucalyptus samples, respectively over a range of torrefaction temperatures between 200-300 ○ C and residence times up to 45 minutes.…”

“…The chemical characteristics -including ultimate analysis-of biomass torrefied under numerous combinations of temperature, reaction time, and feedstock have been investigated experimentally by Arias et al, 2008;Bridgeman et al, 2008;Almeida et al, 2010;Medic et al, 2011). Typically, the torrefied product retains 80-95% of the energy and 70-90% of the mass of the original raw biomass.…”

Effect of torrefaction temperature on properties of Patula pine

“…Arias et al (2008) studied the effect of temperature and residence time on the grindability of Eucaliptus as well as its reactivity with air, using thermogravimetry. As expected, volatiles decreased when temperature increased and the energy content (i.e., its higher heating value) and C content augmented.…”

A Review on Biomass Densification Technologie for Energy Application

“…For example, during torrefaction, biomass loses the tenacious nature that is coupled to the breakdown of the hemicellulose matrix and depolymerization of the cellulose, resulting in a decrease in fiber length Hakkou et al 2006). Torrefaction also results in the shrinking of the biomass structure, making it light-weight, flaky, and fragile, improving the grinding and pulverizing process (Arias et al 2008). Studies conducted on grinding-energy requirements of raw and torrefied biomass like willow, woodcuttings, demolition wood, and coal, indicate a significant reduction in power consumed (by about 70-90%) for torrefied biomass .…”