Equilibrium modelling of trace element behaviour in fluidized bed combustion and gasification of coal

The behaviour of the total 17 elements (As, Be, Cd, Co, Cr, Cu, Hg, Mn, Mo, Ni, Pb, Sb, Se, Sn, Ii, V and Zn) and their compounds during pressurized fluidized bed combustion and gasification (p=12 or p=20 bar, T=380-1380 °C) of coal were modelled using the ChemSage 3.0 equilibrium (eq) model. At this stage no intennetallic compounds were taken into account. The effect of silicates/ minerals on the behaviour of trace elements can also be remarkable. It is possible that the reactions with silicates will bind them to the silicates so strongly that they are unable to vaporise/ react further. Therefore, the reactions of the trace elements with mineral species has been taken into account via the input amount of the trace elements given for the eq calculations. Thus only a small fraction of the coal containing trace elements are allowed to volatilize.