[Stoves] new finding about your Champion stove

Andrew Heggie aj.heggie at gmail.com
Thu Nov 23 12:13:57 CST 2017


Paul  I also would welcome Cheng (I hope that is the correct way to
address?) to the discussion, I too have been seeking an answer to why
rice gasifiers produce a blue flame and this anecdote about sprinkling
on oats is fascinating.

Also I would like to welcome discussion after viewing Dieter Weber on
the link you sent.

I followed the logic of most he said and saw that well premixed and
nearly transparent flame. I wonder about whether the primary zone gets
hot enough in the char burning phase for the endothermy of steam and
carbon dioxide, evolved from batch of fuel not yet gasified, reacting
with hot char to make a significant difference to control.

Dieter mentions that, as the output of the primary zone is above the
autoignition point of the evolved gases, ignition and flaming is
guaranteed, which makes sense yet there seems to also a good degree of
premixing. I would have thought the two processes to be contrary to
each other.

The proof of the pudding is of course in the eating and it all seems
to work well in the demonstration.

David Beedie built just such a gasifier for our first drier, which
Ronal saw when he visited some 15 years ago, but Dieter's (patent)
control "tube" seems a successful innovation which we never had, we
were just relying on primary air control and yes we did experience the
thermal runaway Dieter describes on some occasions.

When these cross-draught gasifiers are used in water heating systems
the parts vulnerable to high temperatures , e.g. around the throat,
can be cooled by the water but ours suffered badly from overheating in
this area. I note also Dieter's prototype seems to be suffering from
distortion and high temperature oxidation and will be interested to
see how he manages a solution in his production model.

Andrew




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