PAH Atmospheric Contamination from Coal Combustion

Abstract

The PAH distribution between those supported on the partculate matter and the ones on the gas phase in the emissions from coal combustion is analysed by fluorescence spectroscopy (FS). The combustion of a low rank coal was carried out in a fluidised bed combustor at temperatures ranging from 700 to 900°C with 20% excess of air and in the presence of sand. The five samples of PAH were sucessively taken for each temperature from the two cyclones (solid phase) and from the sampling system (gas phase) composed of a nylon filter (20 μm), a teflon filter (0.5 μm) and an XAD-2 resin placed at the exit of the fluidised bed combustor (FBC). Dimethylformamide (DMF) was the solvent used for PAH extraction by sonication.

The PAH analyses were performed by fluorescence spectroscopy (FS) in the synchronous mode. The obtained data show a random distribution of each PAH emitted between the five traps independently of the combustion temperature, but the total PAH emission exhibits a defined trend showing a maximum at 750°C.

According to the obtained results, it could be deduced that at the exit of the flow stream from the fluidised bed combustor some inter-radical associations or interconversions between PAH could be produced making variable the amount trapped in each trap but with the total of the studied PAH emission being a function of the combustion temperature.

Key Words:

• coal combustion
• PAH emissions
• analysis