Influence on PAH emissions of the air flow in AFB coal combustion

From the many variables influencing the emissions at the new power stations provided with fluidised bed combustors, the airflow influence on PAH emiss ions at coal AFBC has been studied in this paper. The interval from 700 to 1100 1/h with gradual increases of 100 1/h is studied in detail in relation to polycyclic hydrocarbons emissions. Similar conditions to those used in coal AFBC at the power stations have been simulated in an experimental pilo t plant, laboratory scale. The influence of varying flows on emissions of t he priority PAH pollutants listed by USEPA is analysed keeping constant the percentage of oxygen excess (10%), the combustion temperature (850 degrees C) and the coal particle size (0.5-1 mm). The PAH analyses are performed b y Fluorescence Spectroscopy at the synchronous mode. A dramatic increase of total PAH emission is observed between 850 and 900 1/h probably due to the slugging regime at higher flows. Results on the most relevant polyaromatic s are reported and commented upon. (C) 1999 Elsevier Science Ltd. All right s reserved.