Abstract:
The made calculations of synthesis kinetics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) and a quantitative assessment of their formation in the flue gases at waste incineration plants. It is found that the constant of synthesis of dioxins in the temperature range $500$–$800$ K is k = $(3.92 \pm 0.68) \cdot 10^{-7}$, s$^{-1}$. After determining the residence time of the flue gas in various areas incinerators can calculate the amount of the produced PCDD/F. To evaluate the toxicity of a mixture of PCDD/F in the flue gas introduced toxicity coefficient, which is equal to:
$$
\eta = \frac{TEQ}{\sum \left( PCDD / F \right)}.
$$
The coefficient was calculated for various flue gas of devices for waste destruction by burning. The average toxicity coefficient values in various ranges of PCDD/F concentration in the flue gas of incinerators are shown in the table: For such gases toxicity coefficient is approximately $0.02$ at residence times of gases in the temperature range of the most probable synthesis of dioxins from $0.3$ to $300$ seconds. Reducing or increasing the residence time of the gases increases their toxicity. Results of the study can be used to calculate the amount of dioxins in the flue gases of incinerators and make it possible to assess their toxicity.
Keywords:dioxins, incinerators, flue gases, quantitative assessment, coefficient of toxicity.
Fulltext:
PDF file (176 kB)