VOCs Emission From Coal — Fired Power Station Boiler

Abstract

During the coal combustion process different pollutants are emitted such as fly ash, oxides of carbon, sulfur oxides (SO₂ and SO₃) nitrogen oxides (NO, NO₂) and volatile organic compounds (VOCs). The organic fraction of air pollution contains volatile aliphatic and aromatic hydrocarbons such as: toluene, xylene, ethylbenzene, benzene, aldehydes, PAHs and their methyl-derivatives and heterocyclic compounds of nitrogen, oxygen and sulfur. The content of these compound in exhausted gases has been of particular interest in environmental investigations due to the carcinogenic and mutagenic properties of PAHs, which occur in both the solid phase (adsorbed and associated by fly ash) and the gaseous — vapor phase. The distribution of these pollutants between fly ash and gaseous state depends on the type of furnace and combustion conditions. Seven series of measurement of PAH concentration in the flue gases emitted from a coal — fired boiler were carried out. The Polish high ash coal was burnt. The boiler was operated at a low NO_x emission mode. In the flue gases low NO_x concentration (up to 125 ppm) and not very high PAHs concentrations were determined. The results obtained show low value and a minimum contribution of benzo[a]pyrene and dibenzo[a,h]anthracene to the total PAH emission from this boiler. The results of measurements show no correlation between the PAHs concentrations and the effective power of the boiler.