Co-firing of coal/biomass blends in a pilot plant facility: A comparative study between Opuntia ficus-indica and Pinus radiata

Chile has begun to promote the use of biomass to replace a fraction of the energy produced from coal. However, the power plants are located in the world driest desert, the Atacama Desert, and far from the forest resources. Fortunately, a cactaceous species named Opuntia ficus-indica, has proven to be able to grow under climate desert conditions. In this study the behavior of Opuntia ficus-indica under co-firing conditions with coal, is evaluated and compared to that of Pinus radiata, in terms of heat transfer, ash deposits formation and pollutant emissions in a 150 kW fluidized bed pilot plant. The results revealed a variation of the temperature profile inside the reactor, as well as a relationship between the efficacy factor and the base-acid ratio. The heat transfer coefficients in the dense bed evidenced a decrease in the heat transfers mechanisms attributed to a variation of the mean particle diameter and a greater presence of fuel particles. Under coal-Pine co-firing conditions, an increase in NO formation and a decrease of PM and SO2 concentrations was observed. While co-firing coal with Opuntia showed an increase in the particulate matter and a reduction of NO and SO2 concentrations.