Spray drying sorber(=SDS) has been used for the control of $SO_2$ HCl and NOx from power plants, incinerators and industrial combustion processes. The previous researches, however, were mainly focused on the removal of acidic gas, and the quantitative analysis for the operating condition have not been studied so much. Therefore, in this study, the quantification of major operating parameters for automatic control and the application of equilibrium model and chemical kinetics model for the simultaneous removal of acidic and organic gaseous pollutants from solid waste incinerator were performed.
Experiment was carried out in two parts : a laboratory test for the understanding of 3-phase equilibrium distribution of $SO_2$ and vinyl chloride, and a pilot test for the quatification of major operating parameters of hydrophilic ($SO_2$ and HCl) and hydrophobic (benzene and toluene) pollutants. The concentration of target pollutants were measured by stack gas analyzer and gas chromatography.
Through the equilibrium test, the simulataneous removal of acidic and organic gaseous pollutants by spray drying sorber was possible, and the 3-phase equilibrium distribution of the pollutants was obtained at high temperature.
The removal efficiency of $SO_2$ and HCl in 5 wt% slurry was increased with the increase of stoichiometric ratio, the molecular ratio of lime to pollutant concentration, and the decrease of inflow flue gas temperature in the pilot test. The removal efficiency with the height of spray drying sorber was closely related to temperature profile, and more than 90% of total removal efficiency was gotten in absorption region where the sprayed droplets were saturated with water. Alos, the same result was obtained in case of 3 wt% slurry.
Sprayed droplet size was decreased with the decrease of the slurry flowrate and slurry concentration, and particularly, the variation of the size was very large at the low flowrate and concentration. The droplet size was in inversely proportional to spraying pressure, about 40 ㎛ in 2 f/㎠.
Optimum operating condition considering the economical and stable operation for the removal of acidic gas, is 5 wt% of slurry concentration, 1.2 of stoichiometric ratio and 250℃ of inflow flue gas temperature, and the removal efficiency in this condition may be mpore than 80%. If the stoichiometric ratio is more than 1.2, the clogging in nozzle and its assemblies, and the overloading in bag filter can be occurred. Also the condensation of water can be occurred at the temperature less than 200℃, and the removal efficiency can be decreased due to the decrease of drying time in over 300℃.
The removal efficiency of organic gases, benzene and toluene, was 20 - 60% which is lower than that of acidic gas. The highest removal efficiency was obtained at 1.5 of stoichiometric ratio and 250℃ of inflow flue gas temperture. This means that the length of adsorption region becomes decreased at low temperature (200℃) and the desorption occurs at high temperature(300℃). The removal efficiency of organic gas with the height of spray drying sorber was different to the case of acidic gas, that is, more than 60% for benzene and 90% for toluene of total removal efficiency was gotten in adsorption region, the lower part of the reactor.
The calculated removal efficiency with chemical kinetics model was similar to the measured in pilot test on the whole. The calculated was higher than the measured in 300ppm and lower in 500 ppm of $SO_2$. The calculated was lower than the measured at 1 of stoichiometric ratio and higher in more than 1 for HCl. It resulted from that the mass transfer rate of gaseous HCl to water is much larger than chemical reation rate with lime.
