Torrefaction

Torrefaction of biomass, e.g., wood or grain, is a mild form of pyrolysis at temperatures typically between 200 and 320 °C. Torrefaction changes biomass properties to provide a better fuel quality for combustion and gasification applications. Torrefaction produces a dry product with no biological activity like rotting. Torrefaction combined with densification creates an energy-dense fuel carrier of 20 to 21 GJ/ton lower heating value (LHV). Torrefaction makes the material undergo Maillard reactions. Torrefaction of biomass, e.g., wood or grain, is a mild form of pyrolysis at temperatures typically between 200 and 320 °C. Torrefaction changes biomass properties to provide a better fuel quality for combustion and gasification applications. Torrefaction produces a dry product with no biological activity like rotting. Torrefaction combined with densification creates an energy-dense fuel carrier of 20 to 21 GJ/ton lower heating value (LHV). Torrefaction makes the material undergo Maillard reactions. Biomass can be an important energy source. However, nature provides a large diversity of biomass with varying characteristics. To create highly efficient biomass-to-energy chains, torrefaction of biomass in combination with densification (pelletisation or briquetting) is a promising step to overcome logistic economics in large-scale sustainable energy solutions, i.e. make it easier to transport and store it. Pellets or briquets are lighter, drier, and more stable in storage than the biomass they derive from. Torrefaction is a thermochemical treatment of biomass at 200 to 320 °C (392 to 608ºF). It is carried out under atmospheric pressure and in the absence of oxygen, i.e. with no air. During the torrefaction process, the water contained in the biomass as well as superfluous volatiles are released, and the biopolymers (cellulose, hemicellulose and lignin) partly decompose, giving off various types of volatiles.The final product is the remaining solid, dry, blackened material that is referred to as torrefied biomass or bio-coal.