Promoting the synergistic removal of SO3 aerosols and particles during the flue gas condensation by combining alkali spray and turbulent agglomeration

•A novel synergistic removal technology based on flue gas condensation was proposed.•The synergistic removal mechanisms are explored through numerical simulation.•The removal performance of the combined technology was evaluated by experiments.•Effects of key parameters on removal performance were analyzed. In the condensation process of desulfurized flue gas, not only the flue gas waste heat can be recovered, but also the SO3 aerosols and particles can be removed synergistically. However, the deep purification ability of a single heat exchanger for flue gas is quite poor. In this work, a novel removal technology is proposed for the synergistic removal of SO3 aerosols and particles in the process of flue gas condensation by combining alkali spray and turbulent agglomeration. The agglomeration and capture mechanisms were analyzed by simulating the motion trajectory and calculating the capture efficiency of single alkali droplets. The removal performance of this combined technology was evaluated through experiments. The vertexes generated in the turbulent agglomeration device can promote the agglomeration or coagulation of SO3 aerosols and particles, and finally achieve the enhanced capture effect of these particles by alkali droplets. Compared with the single alkali spray or turbulent agglomeration, the combined technology can achieve better removal performance. The number removal efficiency of the combined technology is up to 78.4% and the mass removal efficiency of SO3 and particles reaches 61.8% and 94.5% respectively under typical conditions. Moreover, the mass removal efficiencies of SO3 aerosols and particles all increase with the increase of initial particle concentration, spray amount of alkaline solution, and flue gas temperature drop.