Evaluation of Ohio fly ash/hydrated lime slurries and Type 1 cement sorbent slurries in the U.C. Pilot spray dryer facility. Final report, September 1, 1993--August 31, 1994

The objectives of this year`s work included an evaluation of the performance of fly ash/hydrated lime as well as hydrated cement sorbents for spray drying adsorption (SDA) of SO{sub 2} from a simulated high-sulfur flue gas. These sorbents were evaluated for several different hydration methods, and under different SDA operating conditions. In addition, the physical properties of surface area and porosity of the sorbents was determined. The most reactive fly ash/hydrated lime sorbent studied was prepared at room temperature with milled fly ash. Milling fly ash prior to hydration with lime did have a beneficial effect on calcium utilization. No benefit in utilization was experienced either by hydrating the slurries at a temperature of 90{degrees}C as compared to hydration at room temperature, or by increasing hydration time. While the surface areas varied greatly from sorbent to sorbent, the pore size distributions indicated ``ink bottle`` pores with surface porosity on the order of 0.5 microns. No correlation could be drawn between the surface area of the sorbents and calcium utilization. These results suggest that the composition of the resulting sorbent might be more important than its surface area. The most effective sorbent studied this year was produced by hydrating cement for 3 days at room temperature. This sorbent provided a removal efficiency and a calcium utilization over 25 percent higher than baseline results at an approach to saturation temperature of 30{degrees}F and a stoichiometric ratio of 0.9. A maximum SO{sub 2} removal efficiency of about 90 percent was experienced with this sorbent at an approach to saturation temperature of 20{degrees}F