In-situ Measurement of CO₂ Column Density and Flame Temperature of Single Biomass Particle Combustion by Laser Absorption Spectroscopy^†

The measurement of the combustion characteristics of a single biomass particle is essential for studying massive biofuel energy conversion process; however, it is challenging due to the small physical scale of the biomass particle flame. In this work, we report an investigation of the combustion behavior of single lignin and single cellulose particle through CO₂ absorption spectroscopy and high-speed photography. The biomass samples are prepared with an initial diameter of about 1.0 mm and are ignited on a heating plate placed inside a multi-pass absorption cell. The shape and size transformation of single biomass particle are recorded through high-speed photography, and the combustion temperature and CO₂ column densities are measured through laser absorption spectroscopy at 4.172 μm. We find that the maximum combustion temperatures are 1662 ± 38 K and 1569 ± 26 K for lignin and cellulose particle, respectively. Besides, we find that CO₂ generation precedes the generation of visible volatile flame for cellulose particle. While for lignin particle, the CO₂ generation is found to be almost at the same time as its volatile combustion stage begins. The measurement technique and results presented in this work are of practical interest for biomass combustion studies and are meaningful for the development of biomass thermal conversion mode.