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Darren,<br>
<br>
Good questions.<br>
<br>
The extra 1/3rd barrel on top is not necessary. See my
publication<font size="-1"> for several examples without that extra
piece.<br>
Barrel-Size Micro-gasification for Combined Heat and Biochar
(CHAB) in “Mini” Industries</font><br>
<a class="moz-txt-link-freetext" href="http://www.drtlud.com/?resource=prt12001">http://www.drtlud.com/?resource=prt12001</a><br>
<br>
Note: the product named re:char is no longer available.
Too expensive, and it lacked some design qualities.<br>
<br>
Adding an outer wall has been done by several persons, and in
different ways. One easy way is to take corrugated metal roofing
and wrap it around the barrel. Others have taken another 200 liter
barrel without top or bottom, cut it once lengthwise, stretch it to
be slighly larger, and use a strip of metal to cover the created
gap. <br>
<br>
One disadvantage of the double barrel at that size is the difficulty
of handling the barrel for dumping out the char. So most people
have not bothered to put the outer cylinder around the 200 Liter
barrel for fuel.<br>
<br>
About chimneys and heights:<br>
A. Consider having the chimney be inside of (or around) the water
tank. See slide 11, bottom center photo shows two water heaters
with heating via the central chimney, with the TLUD placed
underneath. It is smaller than the barrel size that you desire,
but the principle is the same and it can be scaled, such as by
having more chimney pipes to have more heat transfer to the water:<br>
<a class="moz-txt-link-freetext" href="http://www.drtlud.com/?resource=prt06100">http://www.drtlud.com/?resource=prt06100</a> This is from work I
did at ARTI in India in 2005.<br>
<br>
B. It is totally possible to have the hot flue gases exit the top
of the barrel-size TLUD, and then have an optional (use of a damper)
diversion of the gases laterally and even downward to a water heater
which has a sufficiently tall chimney to have the needed draft (or
use some sort of fan or induction system to send the heat where you
want it to go). But do not have any air leakages that reduce the
final draft.<br>
<br>
Darren, as you proceed, please keep us informed. What are you
planning to do? It would be really nice to have a your plans and
success story to tell to others. I and others will gladly assist,
if possible.<br>
<br>
Paul<br>
<pre class="moz-signature" cols="72">Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a>
Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
<div class="moz-cite-prefix">On 5/5/2016 7:37 AM, Darren wrote:<br>
</div>
<blockquote cite="mid:572B3EA0.4040100@vegburner.co.uk" type="cite">Looking
to work on a TLUD design based on a standard oil drum (200-litre
drum (known as a 55-gallon drum in the United States and a
44-gallon drum in the United Kingdom) to produce biochar from well
dried wood.
<br>
<br>
Ideally the stove would have a short chimney so as not to be too
high so that a pot/water tank/oven could be placed above the stove
to be directly heated by the flames.
<br>
<br>
I've had a look about on the internet to see what people have been
building - almost all appear to have an extra 1/3rd of a drum on
top as an 'afterburner' chamber and a reasonably long chimney on
top of this. Making them rather tall for easily positioning
oven/watertank/pots for direct flame heating.
<br>
<br>
None I have seen have an extra, large metal skin / tube
surrounding the barrel to provide secondary air pre heating (as is
done with some smaller TLUD designs). I wonder if adding this
could reduce the total working height of the stove.
<br>
<br>
Looking to make something that is nice and clean burning.
<br>
<br>
Current ideas include -
<br>
<br>
* positioning the chimney/riser at one side of the barrel to allow
heating on the rest of the metal surface next to the riser -
although I suspect a large diameter chimney is required, leaving a
hot surface of limited size.
<br>
<br>
* charging the barrel 2/3rds full with fuel leaving the top 1/3rd
empty as an 'afterburner' - having secondary air holes positioned
to jet in air at this height.
<br>
<br>
Interested in any thoughts people have or any efforts people know
of oil drum TLUD designs where people are trying to reduce the
height, use the heat, or provide heated secondary air.
<br>
<br>
Best
<br>
<br>
Darren
<br>
<br>
see our previous biochar stove at
<a class="moz-txt-link-freetext" href="http://www.appropedia.org/Forest_biochar_rocket_stove">http://www.appropedia.org/Forest_biochar_rocket_stove</a>
<br>
<br>
.
<br>
<br>
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</blockquote>
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