| Summary: | Combustion experiments conducted in domestic stove burning hard coal
demonstrated a predominant influence of the coal chlorine content on the
PCDD/F emissions, together with a pronounced effect of the flue gas
temperature. PCDD/F concentrations of over 100 ng TEQ/m3, three orders of
magnitude higher than in a modern waste incinerator, were measured in the
flue gases of a domestic stove when combusting high chlorine coal (0.31 %).
The PCDD/F concentrations in the flue gases dropped below 0,5 ng TEQ/m3, when
low chlorine coal (0.07 %) was used. When low chlorine coal was impregnated
with NaCl to obtain 0.38 % chlorine content, the emission of the PCDD/Fs
increased by two orders of magnitude. Pronounced nonlinearity of the PCDD/F
concentrations related to chlorine content in the coal was observed. The
combustion of the high chlorine coal yielded PCDD/F concentrations in flue
gases one order of magnitude lower in a fan cooled chimney when compared to
an insulated one, thus indicating formation in the chimney. The influence of
flue gas temperature on the PCDD/F emissions was less pronounced when burning
low chlorine coal. The predominant pathway of the PCDD/F emissions is via
flue gases, 99 % of the TEQ in the case of the high chlorine coal for
insulated chimney.
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