The partitioning of chromium (Cr) in combustion systems was investigated theoretically and experimentally. Theoretical predictions were based on chemical equilibrium, and suggested that hexavalent chromium Cr(VI) was favored by the presence of chlorine (Cl), and diminished by the presence of sulfur (S). Experimental studies employed a 59 kW laboratory-scale combustor with a swirling natural gas diffusion flame through which aqueous Cr solutions were sprayed. Three types of experimental data were obtained. First, and most important, the overall Cr(VI) fraction of the total Cr in the exhaust was measured as a function of initial Cr valence trivalent (III) or hexavalent, and CI and S concentrations. Second, the size segregated distribution of Cr(VI) in the exhaust was explored for the Cr(III) waste feed with and without CI and S. Third, the influence of waste feed Cr valence on the exhaust aerosol particle size distribution was determined. Analytical determinations of Cr(VI) and total Cr are described.
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