Numerical Study of Co-firing Biomass with Lean Coal under Air–Fuel and Oxy-fuel Conditions in a Wall-Fired Utility Boiler

Abstract

Co-firing biomass under oxy-fuel condition is one of the most attractive methods which is conducive to mitigating CO2 emissions by combining the advantages of these two respective technologies. The combustion characteristics of a wall-fired utility boiler operating in this mode have been seldom investigated. The burnout behavior of the blended fuel is still controversial. By using the newly proposed combustion mechanisms, a numerical study was carried out in a 600 MW wall-fired boiler to evaluate the influences of oxy-fuel working condition and biomass share on flow, temperature, O2 distributions, and burnout behavior in this combustion mode. Besides, the effect of biomass injection position was also explored, which has yet to be fully understood. The simulation results show that oxy-fuel working condition affected the combustion characteristics to some extent. The introduction of biomass led to a lower temperature but a better burnout within the furnace. O2 distribution was also correlated to the biomass...