Spray Dryer Absorbers(SDAs) have been widely used for Desulfurization System in MSW Incineration since 1980s. Many studies have shown the relationship between major operating variables(i.e. $SO_2$ flue gas concentration, Ca/S ratio, and Approach to saturation temperature) and $SO_2$ removal efficiency. In this paper the effect of the spray droplet mean diameter on $SO_2$ removal characteristics is examined by the experiments in a SDA pilot plant(Height = 3 m, Diameter = 0.5 m). The Sauter Mean Diameter had been measured by the Malvern System(which detects He-Ne Laser lights scattered by spray droplets) before the pilot plant experiments begun.
In the pilot plant experiment, the spray direction was cocurrnet and the two-fluid external mixing nozzle was used. At first, the effects of major operation variable(Ca/S ratio, Inlet gas temperature) on $SO_2$ removal characteristics are reviewed by experimental results and discussions. And then, the mean diameter effect is examined in several conditions varying Ca/S ratio, inlet temperature, and inlet $SO_2$ concentration. (Tin = 200, 300°C, $SO_2inlet$ = 500, 1000 ppm, Ca/S = 1.0, 2.0, 3.0 )
The results are shown by graphs and it was found that the removal efficiency increases as the droplet mean diameter decreases in most cases. But some exceptional behavoirs appeared in small droplet diameter region because the evaporation time decreases as the droplet diameter decreases. Discussions are followed to obtain the optimal operating conditions.
