Toxic organic emissions from coal combustion

Abstract

Atmospheric fluidized bed combustion (AFBC) is considered to be an environmentally favorable combustion technology where the control of emissions can be integrated into the combustion system. FBC operates at low temperatures, 800–900°C, to prevent thermal NO formation and to favor the sulfur removal by the sorbent, but it has not been taken into account that when coal is burnt, not only NOx, SOx and COx are emitted. In addition, volatile organic pollutants (VOCs) are emitted. From these VOCs, the polycyclic aromatic hydrocarbons (PAHs) constitute one of the most dangerous compounds because of the possibility of interacting with biological nucleophiles. It is expected that new legislation about the regulation on PAH emissions will be very restrictive. In this work, PAH emissions from coal AFBC as a function of the coal combustion variables (combustion temperature, gas flow and percentage of excess oxygen) are reported. In addition, the effect of bed nature on PAH emissions is also assessed.

Polyaromatic hydrocarbon emissions at the standard conditions used at the AFBC power stations are assessed by the study carried out in an AFBC laboratory pilot plant. The PAHs listed by the US EPA as priority pollutants are analyzed by fluorescence spectroscopy (FS) at the synchronous mode.