What is Torrefaction
What is Torrefaction :
Torrefaction is a thermal process used to improve the properties of biomass as a fuel source. It involves heating biomass (such as wood, agricultural waste, or forestry residues) in a low-oxygen environment to a temperature between 200°C and 300°C. This process partially decomposes the biomass, reducing its moisture content, increasing its energy density, and making it easier to grind and transport. Here’s a breakdown of the torrefaction process:
Steps in the Torrefaction Process
- Pre-Drying:
- The biomass is dried to reduce its initial moisture content, usually to below 10%.
- This step is necessary to make the torrefaction process more energy efficient.
- Palletisation (Optional):
- The torrefied biomass can be compressed into pellets or briquettes to improve its handling, storage, and transport.
- Heating and Torrefaction:
- The dried biomass is then heated in an environment with limited oxygen to prevent combustion.
- Temperature is raised to between 200°C and 300°C, which leads to the breakdown of hemicellulose in the biomass. Cellulose and lignin mostly remain intact, preserving the biomass structure.
- At this stage, volatile compounds are released, producing gases such as CO₂, CO, and small amounts of methane and other organic compounds.
- Cooling:
- After torrefaction, the biomass is cooled to stabilize it and prevent oxidation.
- The final product, called “bio-coal” or “torrefied biomass,” has a lower moisture content and is more energy-dense than raw biomass.