[Dioxin-l] Necessity of a water quenche to prevent the de-novo-synthesis?

[Alfred Friedacher]

Is a water quenche necessary for cooling (shockcooling) an offgas from
550°C below 200°C to prevent the "de-novo-synthesis" of PCDD/F´s, or is
for
example a clean air-gas cooler also usable? The residence time of the
offgas is in each cooling system near the same. We had done some
measurements before
and after a water quenche and these shows a de-novo-synthesis of about
200 to 300%. Is the de-novo-synthesis at an air-gas cooler higher or the
same, know
somebody some measurements like ours. Which residence time is allowed
for cooling the offgas through the temperature window that promotes the
most
formation of PCDD/F´s to prevent "de-novo-synthesis".

If anyone know some informations, please reply.

Thanks Alfred