3rd Oxyfuel Combustion Conference IMPACT OF CO2 ON BIOMASS DEVOLATILISATION, NITROGEN PARTITIONING AND CHAR COMBUSTION; A DROP TUBE FURNACE ANALYSIS

Biomass oxy-combustion is attracting considerable attention in recent times because it can achieve negative CO2 emission. While different fundamental issues of oxy-coal combustion are being tackled and pilot demonstrations have been conducted at various scales, little is known about the behaviour of biomass under oxy-fuel combustion. This paper investigates and presents the results of the devolatilisation and combustion behaviour of sawdust in CO2 in a drop tube furnace (DTF) compared to conventional air fired conditions. The effect of devolatilisation temperature and residence time on volatile yield and char burnout was investigated. Also, the influence of CO2 on nitrogen partitioning between volatiles and residual char was considered. From the results, it was observed that higher volatile yields were obtained in oxy conditions. More nitrogen was transformed into the volatile phase in CO2 than in nitrogen, suggesting that less nitrogen will be retained in the char residue and hence less NOx will be formed under oxy-fuel firing conditions. Scanning electron microscope (SEM) images revealed higher porosities of the DTF CO2 chars than