Assessment of PAH emissions as a function of coal combustion variables

The influence of fluidized bed combustion (FBC) temperature and coal rank on polycyclic aromatic hydrocarbon (PAH) emissions was assessed. A low-rank coal and a high-rank coal were burnt in a fluidized bed reactor (FBR) on a laboratory scale. An outlet gas sample was passed through a capture system provided with three traps: nylon filter, Teflon filter and XAD-2 resin. The PAH captured were analysed by fluorescence spectroscopy (FS) after sonic extraction with dimethylformamide (DMF). The results show that the total PAH emission depends mainly on the pyrolytic process and to a lesser degree on the combustion efficiency. Although the total amount of PAH emitted follows a specific trend as a function of the combustion temperature, the amount of each PAH emitted seems to be consequence of a random distribution due to PAH interconversion and association. Under all conditions of combustion, the amount of PAH emitted in the gas phase is higher than that collected in two cyclones preceding the gas sampling location. Copyright (C) 1996 Elsevier Science Ltd.