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TRACE METAL TRANSFORMATION MECHANISMS DURING COAL COMBUSTION
Citation:
Linak*, W P. AND J. L. Wendt. TRACE METAL TRANSFORMATION MECHANISMS DURING COAL COMBUSTION. FUEL PROCESSING TECHNOLOGY. Elsevier Science BV, Amsterdam, Netherlands, 39:173-198, (1994).
Description:
The article reviews mechanisms governing the fate of trace metals during coal combustion and presents new theoretical results that interpret existing data. Emphasis is on predicting the size-segregated speciation of trace metals in pulverized-coal-fired power plant effluents. This facet, which determines how trace metals originally in coal impact the environment, is controlled by fuel composition and combustion conditions. Multicomponent equilibrium calculations, using the latest thermodynamic data available, predicted vaporization/condensation temperatures for antimony, arsenic, beryllium, cadmium, chromium, lead, mercury, nickel, and selenium compounds in coal combustion flue gases, for a representative Illinois No. 6 coal. Experimental data showed that equilibrium provides a good guide on the effect of chlorine on the partitioning of pure nickel, cadmium, and lead salts introduced separately into a gaseous turbulent diffusion flame in an 82 kW combustor. Metal nuclei coagulation mechanisms, examined using existing computer codes, predicted that coagulation did not allow condensed metal nuclei to be scavenged by existing coal ash particles. Rather, literature data on trace metal enrichment on small particles are consistent with processes of reactive scavenging of metals by larger particles.