Effect of boiler output on trace element partitioning during coal combustion in two fluidised-bed power stations

The main aim of this study was a detailed comparison of trace element partitioning during combustion of bituminous coal and lignite in two circulating fluidised-bed units at 40 and 100% boiler output. The elements considered here are: S, Cl, Br, V, Cr, Co, Ni, Cu, Zn, Ge, As, Se, Sn, Sb, W, Hg, and Pb. The trace element concentrations in combustion products show enrichment of most of the elements in fly ash related to bottom ash as well as the slight element enrichment in fly ash at 40% boiler output compared with the 100% output. Using an element balance calculation the proportion of each element in bottom ash, fly ash and emissions was determined. Results showed that at both boiler outputs the highest relative percentages of elements that entered into emissions were Hg and Cl.