OCR Text |
Show statistical correlation of the removal with the key variables. The results indicated that Ca I 5 ratio, Na I Ca ratio, and approach to adiabatic saturation have major effects on 502 removal and that flue gas inlet 502 content and inlet temperature have secondary effects. Table 2 shows Coolside 502 removal data in eight runs, out of a total of S4 runs conducted with Black River hydrated lime. Over all S4 runs, 502 removals ranged from 12 to 57% across the humidi fier and from 15 to 81% across the system (humidifier + baghouse). The simulation test was based on a Box-Behnken statistical experimental design in five process variables: approach to saturation (25 to 45°F), Ca/S mol ratio (0.75 to 2.25), Na/Ca mol ratio (0 to 0.2), inlet 502 content (500 to 2500 ppm wet basis), and flue gas inlet temperature (270 to 330°F). The variable ranges included Edgewater site-specific values. Common flue gas conditions and pilot plant operating conditions are listed in Table 3. I n agreement with previous Coolside test work (l), the 502 removal with Black River lime increased with closer approaches to saturation and with incre2sing Ca/S and Na/Ca ratios. System 502 removal with Black River lime increased from 37 to 56% with a reduction in approach from 45 to 25°F, at 2.3 Ca/S mol/mol, 0.1 Na/Ca mol/mol, 300°F inlet, and 1610 ppm S02 (dry). With an increase in Ca/S mol ratio from 0.8 to 2.3, system S02 removals increased from 25 to 65% at 35°F approach, 0.2/1 Na/Ca mol ratio, 300°F inlet temperature, and 1610 ppmv 502 (dry basis). At constant Ca/S mol ratio of 1.5, increasing the Na/Ca additive ratio from 0 to 0.20 to 0.29 mol/mol increased the system removal from 29 to 56 to 69% (at 25°F approach, 300°F inlet, 1610 ppm 5°2 ) • 502 removal increased moderately with increasing flue gas inlet temperature. For example, the humidifier S02 removal increased from 26 to 33% and system removal increased from 29 to 36%, as inlet temperature increased from 270 to 330°F, at 35°F approach, 1.511 Ca/S - 7 |