Combustion characteristics and synergy behaviors of biomass and coal blending in oxy-fuel conditions: A single particle co-combustion method

Co-combustion biomass and coal can effectively reduce the emission of CO2. O-2/H2O combustion is regarded as the next generation of oxy-fuel combustion technology. By co-combustion biomass and coal under oxy-fuel condition, the emission of CO2 can be minimized. This work investigates the co-combustion characteristics of single particles from pine sawdust (PS) and bituminous coal (BC) in O-2/N-2, O-2/CO2 and O-2/H2O atmospheres at different O-2 mole fractions (21%, 30% and 40%). The experiments were carried out in a drop tube furnace (DTF), and a high speed camera was used to record the combustion process of fuel particles. The combustion temperature was measured by a two-color method. The experiments in O-2/N-2 atmosphere indicate that the particles from pine sawdust and bituminous coal all ignite homogeneously. After replacing H2O for N-2, the combustion temperature of volatiles of blended fuel particles decreases, while the combustion temperature of char increases. The ignition delay time in O-2/H2O atmosphere is shorter than that in O-2/N-2 or O-2/CO2 atmosphere. The combustion temperature of volatiles of blended fuel particles increases as the mass fraction of bituminous coal increases, while the combustion temperature of char of blended fuel particles is higher than that of biomass or bituminous coal. The ignition delay time of blended fuel particles increases with the increasing mass fraction of bituminous coal, and the experimental ignition delay time of blend fuel particles is shorter than the theoretical one. These reveal a synergy during co-combustion process of pine sawdust and bituminous coal.