Solidification characteristics of solid biofuel densified by two-step torrefaction process

Area of Science:

• Biomass energy conversion
• Sustainable materials science
• Chemical engineering

Background:

• Coal coke utilization in industrial furnaces leads to significant carbon dioxide (CO2) emissions.
• Solid biofuels are potential alternatives to coal coke but require improved fuel ratios for industrial applications.
• Key fuel properties include deoxidization, permeability, and carbon pickup capabilities.

Purpose of the Study:

• To develop an innovative densification molding method for solid biofuels.
• To achieve a high CO2 reduction effect through a two-step torrefaction process.
• To enhance the fuel ratio and functional properties of solid biofuels for industrial furnace applications.

Main Methods:

• A two-step torrefaction process was employed at temperatures ranging from 463-773 K.
• The first step involved torrefying raw biomass to remove inhibitory volatile matter.
• The second step involved densifying the torrefied biomass to convert volatile matter to fixed carbon and soften lignin.

Main Results:

• Solid biofuel produced from Japanese cedar using the two-step torrefaction process showed a significantly improved fuel ratio.
• The process effectively converted volatile matter into fixed carbon, enhancing fuel properties.
• Raman spectroscopy elucidated the adhesive mechanism during the carbonization of densified biofuel.

Conclusions:

• The proposed two-step torrefaction and densification method is effective for producing high-quality solid biofuels.
• This method offers a viable pathway for utilizing solid biofuels as a sustainable alternative to coal coke.
• The study provides insights into the structural mechanisms underlying biofuel enhancement.