[Stoves] Tarr analysis ? with DTC

[AJH]

On Sun, 27 Aug 2006 01:41:17 +0200, Frans Peeters wrote:

>Is it true, wood-tar only burns at >850 °C as AJH mentioned.

I don't know in what context you read about this but I think your
inference is mistaken.

I was probably talking about how tars are thought to be cracked in a
downdraught gasifier. Even this is open to query as the various zones
in a downdraught gasifier seem to be quite dynamic, the zones and
their temperature will be variable with the evolution of offgas.

So the figure I posted was the temperature, that seems to be generally
accepted as ideal, at which the offgas leaves the downdraught
gasifier, any lower and the reactions cannot complete, higher means
you are burning fuel gas and hence your cold gas efficiency drops.

In fact we know that, given an air supply only, the char oxidation
zone will reach in excess of the temperature to melt iron, as was
proven by early iron age smelters. This high temperature is modified
by both the extra massflow of volatiles in the wood and the endothermy
of various reactions that occur in the cracking and subsequent
reduction zones, so as the tars pass through the gasifier region they
are subject to a range of temperatures and conditions.

This says nothing about burning tars downstream of any gasifying
device.

AJH