<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Arial; font-size: 12pt; color: #000000'>Crispin, Jock, lists<br>
<br>
I think some of the ideas here may be counterproductive. See below.<br>
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<br>----- Original Message -----<br>From: "Crispin Pemberton-Pigott" <crispinpigott@gmail.com><br>To: "Jock Gill" <jg45@me.com>, biochar-policy@yahoogroups.com, "Stanley Richard" <rstanley@mind.net><br>Cc: "Discussion of biomass cooking stoves" <stoves@lists.bioenergylists.org><br>Sent: Sunday, December 5, 2010 8:03:44 AM<br>Subject: Re: [Stoves] [biochar-policy] More on briquettes and pellets<br><br><style>@font-face {
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}p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman","serif"; }a:link, span.MsoHyperlink { color: blue; text-decoration: underline; }a:visited, span.MsoHyperlinkFollowed { color: purple; text-decoration: underline; }span.apple-style-span { }span.EmailStyle18 { font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125); }.MsoChpDefault { font-size: 10pt; }div.WordSection1 { page: WordSection1; }</style><div class="WordSection1"><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">Dear Jock</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">Very nice web pages and a well presented instructions provided by the link.</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">I have a question relating to the iCan.</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">Have
you tried elevating the primary air holes in the outer can above the
bottom? I understand from the photos that the elevated holes are only on
the inner cans.</span></p>
<p class="MsoNormal"><br>
<span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> <span style="font-weight: bold;">[RWL:
I would go in the opposite direction - put all primary air holes on the
bottom inner can surface - to get more uniform (vertical only) air
flow]</span><br>
</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">The
reason I ask is that I have found benefit from making the primary air
travel downwards at least part of the vertical height. The preheats the
air slightly and provides negative buoyancy reducing draft. As the inner
can starts to heat up, it increases the negative buoyancy because the
inner can is hotter and this interaction tend to self-regulate the
power.</span></p>
<p class="MsoNormal"><br>
<span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> <span style="font-weight: bold;">[RWL:
I don's see the value in reducing draft anywhere - we work hard usually
to achieve it. Re regulating power, I have always been amazed that
with a fixed primary air supply, the power level (as indicated by the
apparent rate of steam bubble formation) was amazingly uniform - over a
full hour. It is easy and cheap to control power levels through
controlling (only) the amount of primary air. I think turn-down ratio
is a very important parameter that needs a lot more work. No gas or
electric stove (I presume propane, ethanol, etc) manufacturer would give
you less than about 3:1 for turn-down ratio. This parameter I think
is one of the main reasons we are going to see increased stove use of
the discarded fans used for cooling computers.</span><br>
</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">If
you get a significant preheat (I would make the gap between the cans no
more than 10mm) you can burn harder, denser fuels that will not
pyrolyse with a normal preheat.</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> <br>
</span></p>
<p class="MsoNormal"> <strong>[RWL: I don't know if the use of "<span style="text-decoration: underline; font-weight: bold;">burn</strong><span style="font-weight: bold;">
harder, denser fuels" was intentional. I believe Jock is only
attempting pyrolysis - being interested in the resultant char for
sequestration and soil improvement.</span> </span><br style="font-weight: bold;">
</p>
<p style="font-weight: bold;" class="MsoNormal"><br>
</p>
<p style="font-weight: bold;" class="MsoNormal"> Re "preheat", there is plenty of opportunity to
use the outer gap for upward flowing preheat of secondary air. Lots of
stoves doing that. The downward flow of primary air will supply not
much heat for the already pretty darn hot pyrolysis front. <br>
</p>
<p style="font-weight: bold;" class="MsoNormal"><br>
</p>
<p style="font-weight: bold;" class="MsoNormal"> Nat Mulcahy's Lucia
stove does have [O=Opposite] downward flowing "primary" (sort of a
misnomer) air - but it is in the inner chamber and carries no oxygen.
The outer chamber does a wonderful job of both preheating and premixing
his pyrolysis gases and secondary air so as to avoid the extra height needed to completely combust a diffusion flame.<br>
</p>
<p style="font-weight: bold;" class="MsoNormal"><br>
</p>
<p style="font-weight: bold;" class="MsoNormal"> I can't remember what
fuels I have ever had trouble pyrolyzing - but the only one I never had
success with is dung - the extreme other end in density/hardness. I
can imagine however that dense fuels might be harder to get started. In
part this is because you need optical energy from the pyrolysis process
to heat neighboring/adjacent particles - and near the top surface, much
of that optical energy is directed upwards. This is a good reason to
use starter/lighter fluids or easy to start fuels (maybe oily material
like peanuts? - which I have never tried in a stove, but peanuts are
easy to light with a match and pincers.)</p>
<p style="font-weight: bold;" class="MsoNormal"><br>
</p>
<p style="font-weight: bold;" class="MsoNormal"> But another thing I
learned early was that there is an enormous (factor of 10?) difference
in interior biomass particle gas flow radially vs longitudinally. This
helps explain why chips and disk shapes light more easily than logs. <br>
</p>
<p style="font-weight: bold;" class="MsoNormal"><br>
</p>
<p style="font-weight: bold;" class="MsoNormal"> In any case, I'd like
more data to prove that hard, dense fuels are a problem for Jock's (or
any) type of pyrolysis stove. Not a problem for most pellets or
briquettes I guess.<br>
<span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"></span></p>
<p style="font-weight: bold;" class="MsoNormal"><br>
</p>
<p class="MsoNormal"><span style="font-weight: bold;">Ron</span><br>
<span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><br>
<span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"><br>
</span></p>
<p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">Give it a try! IT is really easy.</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">Best regards</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);">Crispin</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: "Calibri","sans-serif"; color: rgb(31, 73, 125);"> </span></p><div><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0cm 0cm;"><p class="MsoNormal"><b><span style="font-size: 10pt; font-family: "Tahoma","sans-serif";" lang="EN-US">From:</span></b><span style="font-size: 10pt; font-family: "Tahoma","sans-serif";" lang="EN-US"> Jock Gill [mailto:jg45@me.com] <br><br></span></p></div></div><p class="MsoNormal"> </p><p class="MsoNormal">Ron,</p><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">I
have been able to make very good char, as tested by Hugh McLaughlin,
from grass tablets. These have a diameter of about 1.5 inches and I
break them into wafers about 1/2 CM thick. My first batch of grass
tablet biochar was actually made by Paul Anderson in one of his TLUDs.</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Please see this post from Nov. 2009: <a href="http://www.greaterdemocracy.org/archives/931" target="_blank">http://www.greaterdemocracy.org/archives/931</a></p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">I
also find that quenching the biochar at the end of the pyrolysis is not
critical at all. If I leave one of my iCans overnight, I lose less
than half the charcoal. My guess is that this is the result of tuning
the iCan for the least amount of primary air. I have noted that when
the pyrolysis is over, the bed of charcoal emits "smoke". My goal is
for zero smoke, but find that I can still get god biochar if the smoke
is essentially gone in less than two minutes. My practice is to only
quench after the smoke has essentially finished f within in about 3
minutes after the pyrolysis flames extinguish themselves.</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Cheers,</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal">Jock</p></div><div><p class="MsoNormal"> </p></div><div><p class="MsoNormal"> </p><div><div><div><div><div><div><div><div><div><div><div><p class="MsoNormal"><span style="font-size: 10.5pt; font-family: "Arial","sans-serif"; color: black;">Jock Gill</span></p></div><div><p class="MsoNormal"><span style="font-size: 10.5pt; font-family: "Arial","sans-serif"; color: black;">P.O. Box 3</span></p></div><div><p class="MsoNormal"><span style="font-size: 10.5pt; font-family: "Arial","sans-serif"; color: black;">Peacham, VT 05862</span></p></div><div><p class="MsoNormal"><span style="font-size: 10.5pt; font-family: "Arial","sans-serif"; color: black;">Carbon Negative Solutions</span></p></div><div id="270E0338-CFAF-4573-BDD2-82CC857ABF31"><div><p class="MsoNormal"><span style="font-size: 10.5pt; font-family: "Arial","sans-serif"; color: black;">(G) (802) 503-1258</span></p></div></div><p class="MsoNormal" style="margin-bottom: 12pt;"><span style="font-size: 10.5pt; font-family: "Arial","sans-serif"; color: black;"> </span></p></div></div></div></div></div></div></div></div></div></div><p class="MsoNormal"> </p><div><div><p class="MsoNormal">On Dec 5, 2010, at 1:42 AM, <a href="mailto:rongretlarson@comcast.net" target="_blank">rongretlarson@comcast.net</a> wrote:</p></div><p class="MsoNormal"><br><br></p><div><p class="MsoNormal" style="background: none repeat scroll 0% 0% white;"> </p><div id="ygrp-mlmsg"><div id="ygrp-msg"><div id="ygrp-text"><div><p class="MsoNormal" style="background: none repeat scroll 0% 0% white;"> </p></div><div><div><div><p class="MsoNormal" style="background: none repeat scroll 0% 0% white;"><span style="font-family: "Arial","sans-serif"; color: black;">Richard and 2 lists:<br><br>Thanks
for the complete response. I conclude that pellets and briquettes are
possibly able to act similarly in char-making stoves, but briquettes
look better in traditional stoves. Apparently not much comparative work
done yet for advantages of production of one vs the other. </span></p></div></div></div></div></div></div></div></div><p class="MsoNormal"> </p></div></div><br>_______________________________________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br>Stoves mailing list<br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br>http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br>http://www.bioenergylists.org/<br>Stoves@lists.bioenergylists.org<br>http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br></div></body></html>