Trace element partitioning during coal gasification

The fate of trace element pollutants in integrated gasification combined-cycle (IGCC) systems is closely tied to their volatilization in the gasifier and subsequent condensation or reaction with fine fly ash particles. The results of an experimental bench-scale programme to measure the partitioning of selected trace elements during atmospheric pressure entrained flow gasification of Illinois No.6 bituminous coal are presented. The experimental data are used in conjunction with thermodynamic equilibrium calculations to investigate the downstream behaviour of the volatile elements. It is shown that a significant mass fraction of each of the elements As, Se, Sb, Pb and Hg vaporizes during gasification of this coal, whereas Cd, Cr, Co, Mn, Ni, U and Th are relatively non-volatile. Under the reducing conditions associated with the gasifier product gas, As, Sb, Pb, Hg, and Se remain in the vapour phase at temperatures of 773 to 873 K, the operating range of most hot gas removal systems. (C) 1996 Elsevier Science Ltd.