Torrefaction

Basics

Torrefaction removes moisture and some volatiles from wood. Further heating leads to carbonization, which mobilizes more volatiles and changes the properties of some of the constituents (e.g. due to polymerization).

• A mild form of Biomass Pyrolysis at temperatures typically between 200 and 320 °C
• Produces mainly Tar , and Charcoal
• Can clog vents etc if not accounted for in design
• If intentional the calorific value of biomass can be greatly increased
• Benefits are:
  • Higher energy density
  • More homogeneous composition
  • Hydrophobic behavior
  • Elimination of biological activity
  • Improved grindability.
  • Seems to be via coating the resulting char in the tar via it not being extracted/removed in the flue gas?
• Along with the products of Hydrothermal Carbonization , it is often referred to informally as Bio-Coal given it's similarities to Bituminous Coal / Sub-Bituminous Coal ( Lignite / Brown Coal )

Internal Links

• Bio-Tar
• Bio-Asphalt
• Wood Preservation by Carbonization
• Pelletized biomass and Wood Chips
• Kon-Tiki Kiln and Biochar

External Links

• The Wikipedia Page on Torrefaction
• An Article by " The Coalition for Sustainable Rail " titled "Torrefied Biomass"
• An Article in Biomass Magazine Titled "Why Hasn’t Torrefaction Taken Off?" (Essentially an advertisement for " Advanced Torrefaction Systems LLC " , but interesting nonetheless)
• A 2021 Article in Frontiers in Energy Research: Bioenergy and Biofuels Titled "Torrefied Biomass and Where Is the Sector Currently Standing in Terms of Research, Technology Development, and Implementation"