Journal of Chemical Engineering of Japan, Vol.29, No.3, 494-500, 1996
The Behavior of Heavy-Metal Cr, Pb and Cd During Waste Incineration in Fluidized-Bed Under Various Chlorine Additives
Previous theoretical studies have demonstrated that chlorine-containing materials significantly affected heavy metals behavior during incineration. In this study, we examine the effects of operating temperature in both primary and second combustion chambers along with those of various chlorine-containing materials (organic or inorganic) on metal partitioning in sand-bed sorbents, fly ash, waste water, and flue gas. A bubbling fluidized bed made from 310 stainless steel (100 cm bed height; 10 cm ID; and 100 cm freeboard; 25 cm ID) was used, in addition to two cyclones and a wet scrubber. The synthetic solid wastes used were plastics, sawdust and water. These results indicated that the fluidized medium (silica sands) can absorb a high proportion of metals in the incineration process; in addition, the extent of absorption ability follows the sequence : Pb>Cr>Cd. The effect of organic and inorganic chlorine on metal partitioning were very different; organic chlorine (P.V.C.) caused a more serious metal emission than inorganic chlorine (NaCl). The operating temperature and chemical reaction influenced absorption by the fluidized media. Within the operating temperature ranges, 500 similar to 600 degrees C for the main combustion chamber, 600 similar to 800 degrees C for the second combustion chamber), the effect of freeboard temperature on the metal partitioning is insignificant.