Wp. Linak et al., SORBENT CAPTURE OF NICKEL, LEAD AND CADMIUM IN A LABORATORY SWIRL FLAME INCINERATOR, Combustion and flame, 100(1-2), 1995, pp. 241-250
The in situ capture of toxic metals by sorbents was investigated in a
small semi-industrial scale 82 kW research combustor. Metals considere
d were nickel, lead, and cadmium. These metals were introduced into th
e system as aqueous nitrate solutions, sprayed down the center of a na
tural gas flame, supported on a variable swirl burner. Kaolinite, baux
ite, and hydrated lime were injected along the centerline in the postf
lame, near the peak system temperature. Measurements of both the submi
cron aerosol size distribution and the size segregated particulate com
position in the exhaust allowed the effects of sorbent injection to be
ascertained, both with and without the presence of chlorine. Lead and
cadmium could be almost completely scavenged by kaolinite, which form
ed melted particles. Bauxite, which did not melt, was exceedingly effe
ctive in capturing cadmium. However, chlorine inhibited metal capture
in these instances. Hydrated lime also captured cadmium to form a eute
ctic melt, and this process was slightly enhanced by chlorine. Nickel
alone did not significantly vaporize and was not captured by kaolinite
. However, in the presence of chlorine, nickel did vaporize and was ef
fectively captured. These results are interpreted and compared to benc
h scale results in the literature. Two mechanisms, or scenarios, for t
oxic metal capture are presented.