Oxy-combustion Behavior of Torrefied Biomass Particles

Abstract

A fundamental investigation was conducted on the combustion characteristics of torrefied biomass in both air and O2/CO2 gases containing 21% or 30% oxygen mole fractions. These gases simulated oxy-combustion environments. The targeted torrefied biomass types were waste crops, both herbaceous and woody. The experimental setup that was used in this investigation consisted of a drop-tube furnace, operated at a wall temperature of 1400 K, a high-speed high-resolution camera. Entire luminous particle combustion profiles of single particles were recorded by means of high-speed high-resolution cinematography. Combustion of these particles took place in two phases. Initially, volatiles evolved and burned in spherical/ellipsoidal envelope flames; then, upon extinction of these flames, char residues ignited and burned. Replacing air as the furnace background gas with 21%O2-79%CO2 reduced the luminosity of flame and the lengthened the burnout times; and increasing the oxygen mole fraction further to 30% increased the luminosity of the flame and shortened the burnout times.