Ron,<br><br>You bring up a very good point here. If the biomass is uniform, granular and dry, it becomes very easy to process in a TLUD. That is why it is so appealing to work with biomass that is already uniform, granular and dry, such as rice hulls and coffee husks. <br>
<br>But if we have biomass that is not uniform, granular and dry (such as straw, pine needles or sawdust), then we might think about drying and pelletizing it. In this way we have a top-quality gasifier fuel. This allows us to take full advantage of both the biochar and gas. In the case of rice hulls and coffee husks, the gas has a much greater commercial value than the biochar. In making biochar it is such a pity to waste the gas.<br>
<br>Also when we pelletize biomass, the bulk density can reach as high as 600 kgs/m3. This means that if we use a gasifier for purposes of household cooking, the height of the reactor has to be only a fraction of the height of a reactor utilizing undensified biomass such as rice hulls (of a bulk density of less than 100 kgs/m3). If we do not change the height of the reactor, then cooking times per batch can last three or four hours. When we have thousands of households and small business using gasifiers, then we do not have to think about making biochar as an independent activity.<br>
<br>I really like small pellets of a diameter of about 6 mm. Of course there is the cost of buying a pellet machine. But they are quite cheap out of China. And there is the cost of electricity or fuel to make the pellets. But this cost is easily offset by the value of the syngas produced. Even in a poor country such as Vietnam, it is easy to buy pellets in local markets.<br>
<br>Thanks.<br>Paul<br><br><div class="gmail_quote">On Sun, Sep 30, 2012 at 9:48 AM, Ronald Hongsermeier <span dir="ltr"><<a href="mailto:rwhongser@web.de" target="_blank">rwhongser@web.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Dear Alex, <br>
<br>
I haven't carefully read the whole thread but haven't seen
granularity of fuel addressed. Isn't that what makes a lot of
difference in the flame/gas quality ( along with the moisture
content, of course ) and determines the necessity of either using or
not using forced air? Regarding Dr. Karve's drums I'm wondering how
careful everyone is in emphasizing fuel moisture and
particularity/uniformity issues in using these tools.<br>
<br>
I think my first sentence above applies to both DD (Imberts or
others) and TLUD's. <br>
<br>
regards,<br>
Ronald von der Oktoberfestnähe<br>
<br>
(mein heutiger Name wird nur dann getragen bei einer
Bierleichensichtungsrate von > 1 / Tag ;-) )<br>
<br>
<br>
<br>
<br>
<div>On 29.09.2012 20:55, Alex English
wrote:<br>
</div>
<blockquote type="cite">
<p>Tom,<br>
I guess it may depend on what you consider a clean burn. My
experiments focused the gases through a smaller out let pipe and
then added the secondary air. So for a two foot diameter drum
the pipe was three inches in diameter. Air was introduced near
the top having only half that distance to penetrate, and
combustion occurred in a six inch diameter chimney , six feet
tall above.</p>
<p>Combustion was measurably good to very good nineteen times out
of twenty.</p>
<p>So, what indeed is the limit?<br>
Alex</p>
<div class="gmail_quote">On 2012-09-29 11:47 AM, "Tom Miles" <<a href="mailto:tmiles@trmiles.com" target="_blank">tmiles@trmiles.com</a>>
wrote:<br type="attribution">
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div link="blue" vlink="purple" lang="EN-US">
<div>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">AD,
Paul, Kobus and others. Many thanks for the
suggestions. </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">What
is the largest practical size (kg fuel/hr, kW) for a
single TLUD with a clean stack for heat recovery?
There must be a limit to the air penetration to get a
clean gas burn form a natural draft stack or even a
fan driven TLUD. </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d">Tom
</span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1f497d"> </span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">
<a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a>
[mailto:<a href="mailto:stoves-bounces@lists.bioenergylists.org" target="_blank">stoves-bounces@lists.bioenergylists.org</a>]
<b>On Behalf Of </b>Anand Karve<br>
<b>Sent:</b> Friday, September 28, 2012 11:22 PM<br>
<b>To:</b> Discussion of biomass cooking stoves<br>
<b>Subject:</b> Re: [Stoves] Fabricated Burn Barrel
TLUDS</span></p>
<p class="MsoNormal"> </p>
<div>
<p class="MsoNormal">Dear Tom,</p>
</div>
<div>
<p class="MsoNormal">we regularly supply charring kilns
made out of used 55 gallon drums. The kilns are based
on the TLUD principle. The cost of a kiln plus an
extra barrel for storing the char, is about US$100. We
have sold more than 100 such kilns in India and have
also trained a number of persons from India
and Africa. These kilns are so easy to manufacture,
that we ask the trainees to photograph and take
measurements of our kiln so that they can copy the
design. In many instances, people buy a kiln from us,
because they feel that their local fabricator would be
better able to copy the design from an actual object
than from a blue print or a photograph.</p>
</div>
<div>
<p class="MsoNormal">The advantage of using 55 gallon
drums is that used drums are available at a relatively
low cost, and the kilns are portable. Instead of
transporting the biomass, one transports the kiln to
the location where the biomass is available, and
brings back only the charred material, which weighs
only a third as much as the biomass. </p>
</div>
<div>
<p class="MsoNormal">Yours</p>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt">A.D.Karve</p>
</div>
<div>
<p class="MsoNormal">On Fri, Sep 28, 2012 at 11:42 PM,
Tom Miles <<a href="mailto:tmiles@trmiles.com" target="_blank">tmiles@trmiles.com</a>>
wrote:</p>
<div>
<div>
<p class="MsoNormal">Am often asked if there is a
burn barrel sized TLUD that is commercially
fabricated. We’ve seen some great DIY with Doug’s
Jolly Roger and others. Is anyone fabricating a 55
gal drum sized TLUD that can be used for regular
biochar production? If so, what is the cost and
availability?</p>
<p class="MsoNormal"> </p>
<p class="MsoNormal">Thanks</p>
<p class="MsoNormal"><span style="color:#888888"> </span></p>
<p class="MsoNormal"><span style="color:#888888">Tom
Miles </span></p>
</div>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
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<p class="MsoNormal" style="margin-bottom:12.0pt">
<br>
<br clear="all">
<br>
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***<br>
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