Steam torrefaction of Eucalyptus globulus for producing black pellets: A pilot-scale experience

Area of Science:

• Biomass energy conversion
• Thermochemical processing
• Materials science

Background:

• Biomass utilization for energy is crucial for sustainability.
• Torrefaction is a promising thermochemical pretreatment method.
• Eucalyptus globulus is a widely available biomass feedstock.

Purpose of the Study:

• To investigate the effects of steam torrefaction on Eucalyptus globulus properties.
• To evaluate the combustion behavior and physical characteristics of torrefied biomass pellets.
• To assess the potential of torrefied biomass as a coal substitute.

Main Methods:

• Steam torrefaction of Eucalyptus globulus at 245-265°C in a pilot plant.
• Pelletization of torrefied biomass using a 300 kg/h unit.
• Durability, density, and combustion tests on pellets; FTIR analysis for structural changes.

Main Results:

• Increasing torrefaction temperature reduced hemicellulose and mass yield (MY).
• A linear relationship was found between energy yield (EY) and mass yield (EY=[1.04-0.9(1-MY)]).
• Torrefied biomass showed enhanced combustion stability and high-density pellets (13-14 GJ/m³), comparable to low-rank coals.

Conclusions:

• Steam torrefaction significantly improves the combustion properties of Eucalyptus globulus.
• Torrefied biomass pellets offer a viable alternative to fossil fuels like low-rank coal.
• The process yields durable, energy-dense pellets suitable for industrial energy applications.