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<div class="moz-cite-prefix">Kevin,<br>
<br>
The objective of the filler is two-fold: <br>
<br>
One reason is precisely to reduce the maximum flow of primary
air. Without resistance, too much primary air can race through
the loose pile of biomass, reach too much of the biomass at the
same time, and have an excessive fire without much control.
Control simply by a "gate" at the entrance of the primary air is
usually insufficient.<br>
<br>
Second reason is that burning embers at the top of loosely packed
fuel can sometimes fall to lower areas of the fuel bed and ignite
the raw fuel there. This defeats the process of the pyrolysis
front that starts at the top and should progress slowly and
uniformly downward through the bed of fuel. That migrating
pyrolytic front is THE most important and distinguishing feature
of the TLUD stoves. Ignition at the top and having updraft are
not the single-most defining characteristics of TLUD stoves (even
though that is what the name says). Maybe I should have called
it Migrating Pyrolytic Front Gasification (or MPFG), but TLUD is
the accepted name now. [And Tom Reed always thanks me for
getting away from the Inverted DownDraft (IDD) name that was not
well understood.]<br>
<br>
Important note: When the pyrolytic front correctly reaches the
bottom of the batch of fuel, the combustion style changes to be
Bottom-Burning UpDraft (call it BBUD if you must have an acronym,
but note that at the start it was NOT IGNITED or lit at the
bottom). And there is no more migration/movement of a
"gas-making" zone. <br>
<br>
Also note: When the batch has been pyrolyzed, the burning at the
bottom is "char-gasification" and can be at forge temperatures
that can damage the metal pieces. There is still restricted flow
of primary air. The hot gases go upward. IF additional raw
biomass fuel is placed onto the top of that charcoal, it will be
heated, dried, torrified, and eventually pyrolyzed, giving
additional pyrolytic gases that can be combusted where the
incoming secondary air enters. But this is NOT operating as a
TLUD stove (with MPFG). This type of bottom-burning gasifier is
well illustrated by the Oorja stove (former BP, now First Energy)
in India. It has a cast-iron cup in the bottom to protect the
other metal parts, and that cup glows red-hot after continual
use. [Technical note: Stove testing should measure separately
the emissions during each of the different combustion modes
instead of just reporting averages that include emissions from two
or more combustion modes. I think we can do some of that at this
summer's Stove Camps at CREEC - Uganda and at Aprovecho -
Oregon-USA where emissions equipment is available.]<br>
<br>
About terminology: A bucket stove or mud stove or Rocket stove
and many others can be ignited at the bottom of a container and
they do have updraft, BUT they are NOT GASIFIER devices. So the
designation BLUD is not relevant. UD and DD and TLUD are
designations historically for gasifiers, which means that the
gases are created in one place that is NOT the same place as the
combustion or other use of the gases.<br>
<br>
Paul (James, please get this onto
the drtlud.com website in edited format.)<br>
<br>
<pre class="moz-signature" cols="72">Paul S. Anderson, PhD aka "Dr TLUD"
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>
On 5/6/2013 1:17 AM, Kevin wrote:<br>
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<div><font face="Arial">Dear Paul</font></div>
<div> </div>
<blockquote style="BORDER-LEFT: #000000 2px solid;">
<div style="FONT: 10pt arial;">----- Original Message
----- </div>
<div style="FONT: 10pt arial;BACKGROUND: #e4e4e4;"><b>From:</b>
<a moz-do-not-send="true" title="psanders@ilstu.edu"
href="mailto:psanders@ilstu.edu">Paul Anderson</a> </div>
<div style="FONT: 10pt arial;"><b>To:</b> <a
moz-do-not-send="true"
title="stoves@lists.bioenergylists.org"
href="mailto:stoves@lists.bioenergylists.org">Discussion
of biomass cooking stoves</a> </div>
<div style="FONT: 10pt arial;"><b>Cc:</b> <a
moz-do-not-send="true" title="kchisholm@seaside.ns.ca"
href="mailto:kchisholm@seaside.ns.ca">Kevin</a> ; <a
moz-do-not-send="true" title="biochar@yahoogroups.com"
href="mailto:biochar@yahoogroups.com">biochar@yahoogroups.com</a>
; <a moz-do-not-send="true" title="jss@bitmaxim.com"
href="mailto:jss@bitmaxim.com">James S. Schoner</a> ;
<a moz-do-not-send="true" title="wastemin1@verizon.net"
href="mailto:wastemin1@verizon.net">Hugh McLaughlin</a>
</div>
<div style="FONT: 10pt arial;"><b>Sent:</b> Sunday, May
05, 2013 6:33 PM</div>
<div style="FONT: 10pt arial;"><b>Subject:</b> Re:
[Stoves] [biochar] Charcoal as space filler in TLUD
reactors</div>
<div><br>
</div>
<div class="moz-cite-prefix">Kevin,<br>
<br>
The "charcoal as filler" is not about consuming the
charcoal. </div>
<div class="moz-cite-prefix"> </div>
<div class="moz-cite-prefix"><font face="Arial"># Sorry, I
missed that.</font></div>
<div class="moz-cite-prefix"> </div>
<div class="moz-cite-prefix"> The charcoal is "almost"
non-active in the pyrloysis of the new biomass. This
is a discussion about limiting air flows with a filler
that mostly is inactive in environments that are at 650
C without oxygen. </div>
<div class="moz-cite-prefix"> </div>
<div class="moz-cite-prefix"><font face="Arial"># Why do
you feel it would be advantageous to limit air flow
with an inert filler? If the char was significantly
larger or smaller than the biomass fuel, it could
significantly increase pressure drop through the bed,
and would likely reduce maximum flow. </font></div>
<div class="moz-cite-prefix"> </div>
<div class="moz-cite-prefix"><font face="Arial"># Thanks.</font></div>
<div class="moz-cite-prefix"> [ Note that I avoid
using the word "inert" in this discussion.]</div>
<div class="moz-cite-prefix"> </div>
<div class="moz-cite-prefix"><font face="Arial">Best
wishes,</font></div>
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<div><font face="Arial">Kevin</font></div>
<div class="moz-cite-prefix"><br>
<br>
Paul<br>
</div>
<div class="moz-cite-prefix">
<pre class="moz-signature" cols="72">Paul S. Anderson, PhD aka "Dr TLUD"
Email: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a> Skype: paultlud Phone: +1-309-452-7072
Website: <a moz-do-not-send="true" class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
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