Element Behaviour in Coal Combustion – Comparison of Element Contents in Unburnt Carbon, Coal and Bottom Ash

Abstract

The behaviour of S, Se, As, Cl, Cr, V, Ni, Co, Cu, Zn, Pb and Hg in coal combustion was studied in two fluidised-bed power stations (at 40 % or 100 % boiler output, bituminous coal and lignite), in co-combustion of coal and wastes and in the combustion in a pilot-scale unit. Volatility of trace elements in the combustion chamber was evaluated by comparison of the element content in coal, unburnt carbon and bottom ash. In all the units mentioned above, S, Se, Cl, Hg and As were volatile, which corresponds with the results reported in literature. Cu, V, Co, Ni a Cr were non-volatile in the power stations, while in the pilot-scale unit volatilization prevailed. On the other hand, Zn was non-volatile only in the Tisová power station, where lignite was burnt. When compared with other elements, the behaviour of Pb in combustion was most dependent on the combustion unit type, the coal burnt and boiler output.