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Scott, (Third of 3 replies to about a dozen messages on this
topic. Not in any special order. I thank everyone for their
comments.)<br>
<br>
Very nice explanation. (a definition would probably be shorter).
Only one suggested correction. You wrote in first sentence:
<blockquote type="cite">while producing combustible energy. </blockquote>
Should be while producing combustible gases. When the
gases burn then you have the release of energy.<br>
<br>
The comments sent by Kirk Harris (in a later message) are also
highly appropriate for some changes.<br>
<br>
Paul<br>
<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 12/10/2017 10:33 AM, Scott Zager
wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">Dear
stovers:<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">The
recent discussion inspired me to amend a working definition
I have been writing for a glossary on biochar. I was hoping
that perhaps more experienced stovers would be willing to
review my definition of a TLUD. I would appreciate any
comments for revision. Thank you.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif">P.S.
I am trying to define a “Retort” next.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><o:p></o:p></p>
<p class="MsoNormal" style="text-autospace:none"><b>TLUD
(top-lit, up-draft) Pyrolyzer</b>: TLUD gasifiers
automatically make char while producing combustible energy. A
TLUD is basically a canister filled with biomass to create a
“fuel bed”. TLUDs are either batch-fed or continuously-fed,
biomass gasifiers that are loaded with a feedstock (biomass in
the form of wood chips, pellets, briquettes, etc.). Air
enters the canister through holes in a grate at the bottom of
the cylinder. The fuel bed is ignited on top, burning some of
the volatile gases to generate the heat needed to gasify
un-pyrolyzed feedstock. The ignition front travels down
through the fuel by heat radiating into the raw fuel, which
dries it and initiates thermochemical conversion of the
feedstock into char and wood-gas. The "ignition front" is
actually a pyrolysis reaction within the canister that moves
through the feedstock, in what is called a "Migratory
Pyrolytic Front" (MPF). The ignition front is maintained by
air (i.e., primary air) that enters the bottom of the
cylinder. Residual char is left on top of the fuel bed as the
MPF moves downward. The MPF creates a draft for primary air,
which can be also supplemented and controlled by forced air
pushed inward from fans. When the MPF reaches the bottom of
the cylinder, the smoke-producing reaction is complete, and
pyrolysis ends. At this point the char is removed from the
cylinder. If the char is not removed, it may burn slowly from
the bottom up unless the fire is snuffed out by the lack of
oxygen. During pyrolysis, volatile gasses in the form of white
smoke (wood-gas) dissipate upwards into a secondary combustion
chamber where it is consumed to produce heat and carbon
dioxide (mostly). The gas flame in the secondary chamber is
supported by air (secondary air) entering through side-holes
or a gap near the top of the cylinder. The primary and
secondary air can move by natural draft, relying on the
buoyancy of hot gasses to push air through the system, or
draft air can be forced – and controlled – by using a
variable-speed, small electric fan to push the air. The
pyrolysis leaves behind char rather than ash for two reasons:
(1) as the MPF moves downwards, it thermochemically
transforms new fuel at a rate faster than oxygen is supplied
to combust it, and (2) pyrolysis and the combustion of
volatiles can occur much faster than the combustion of char,
which requires a higher level of activation energy.<a
style="mso-footnote-id:ftn1" href="#_ftn1" name="_ftnref1"
title="" moz-do-not-send="true"><sup>1</sup></a>
Continuously-fed TLUDs use augers to maintain the MPF in a
stationary position by supplying new feedstock into the bottom
of the cylinder while removing char through an upward port
into a quenching container that extinguishes any reactions,
cools the char and stores it.<o:p></o:p></p>
<p class="MsoNormal" style="text-autospace:none"><o:p> </o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri",sans-serif"><o:p> </o:p></span></p>
<br>
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