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<p class="MsoNormal">Stovers,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The message below is a multi-person exchange about cooking heat that is taking place on the Biochar Discussion Group. I think it is important to any “Stovers” who are not getting those messages. (If you are on the Biochar Group, you
have already seen this message. No additional material has been added.)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Paul<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Doc / Dr TLUD / Paul S. Anderson, PhD --- Website: <a href="http://www.drtlud.com/">
<span style="color:#0563C1">www.drtlud.com</span></a><o:p></o:p></p>
<p class="MsoNormal"> Email: <a href="mailto:psanders@ilstu.edu"><span style="color:#0563C1">psanders@ilstu.edu</span></a> Skype: paultlud<o:p></o:p></p>
<p class="MsoNormal"> Phone: Office: 309-452-7072 Mobile & WhatsApp: 309-531-4434<o:p></o:p></p>
<p class="MsoNormal">Exec. Dir. of Juntos Energy Solutions NFP Go to: <a href="http://www.juntosnfp.org/">
<span style="color:#0563C1">www.JuntosNFP.org</span></a> <o:p></o:p></p>
<p class="MsoNormal">Inventor of RoCC kilns for biochar and energy: See <a href="http://www.woodgas.com">
<span style="color:#0563C1">www.woodgas.com</span></a> <o:p></o:p></p>
<p class="MsoNormal">Author of “<i>A Capitalist Carol</i>” (free digital copies at
<a href="http://www.capitalism21.org/"><span style="color:#0563C1">www.capitalism21.org</span></a>)<o:p></o:p></p>
<p class="MsoNormal"> with pages 88 – 94 about solving the world crisis for clean cookstoves.
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> main@Biochar.groups.io <main@Biochar.groups.io>
<b>On Behalf Of </b>Paul S Anderson via groups.io<br>
<b>Sent:</b> Saturday, August 8, 2020 10:14 PM<br>
<b>To:</b> main@Biochar.groups.io; Hugh McLaughlin <wastemin1@verizon.net><br>
<b>Cc:</b> Kevin McLean > <info@sun24.solar><br>
<b>Subject:</b> Re: [Biochar] An example of the exotherm during pyrolysis<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I reply to Ron (and Kevin), and with thanks to Hugh for his scientific explanations about pyrolysis.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Ron wrote: <o:p></o:p></p>
<p class="MsoNormal"><b>Should Kevin and I forget retorts as a help in furthering the replacement of fire woodd with corn cobs (now mostly left to rot in the field)?</b><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">IMBO (In My Biased Opinion). I would says “Yes, forget retorts.” Now in need to explain my thinking.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">1. A retort does not provide a uniform supply of heat which cooks desire. Retorts do not give combustible gases from the very early minutes. And, as shown in Hugh’s research, when the heat does come, it will be much in a relatively
short time (again, not good for cooking).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">2. From the little that I saw of Kevin’s simple (very low cost) TLUD, there was minimal or no attempt to restrict the entry of the primary air. The result has two disadvantages:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">A. There was a faster than desired release of the gases (and the resultant cooking flame).
<o:p></o:p></p>
<p class="MsoNormal">B. The created char was subjected to too much O2 (in the surplus air) and subsequently burned (char-gasified) to the point that you are lamenting the low yield of char.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">3. Based on 2 above, the there is some solution to both problems when there is actual control of the entry of primary air. Such control come with an extra cost. IMO, that cost (for a mostly sealed container and control of air supply)
is what makes the TLUDs stoves successful. Success with TLUD technology is closely tied with air control.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">4. My experience with dry maize cobs as fuel is quite successful. Cobs are less dense than woody stuff, so the TLUD fuel chamber needs to be larger. That, unfortunately, also adds to the cost.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">5. Sorry, the above is not good new when a major criterium of success is to have ultra-low cost of the physical stove. My counter argument that is to justify the extra cost of air control is to bring to the stove users (the cooks and
their families) the financial benefits of producing biochar/charcoal that can be sold and/or bring in some revenue as carbon offsets/removals.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">6. Tying this back to Hugh’s work with exothermic boost of heat, that boost does take place in TLUD stoves, but it is occurring at a consistent rate in each millimeter of the descending migratory pyrolytic front. (MPF).
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Paul<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Doc / Dr TLUD / Paul S. Anderson, PhD --- Website: <a href="http://www.drtlud.com/">
<span style="color:#0563C1">www.drtlud.com</span></a><o:p></o:p></p>
<p class="MsoNormal"> Email: <a href="mailto:psanders@ilstu.edu"><span style="color:#0563C1">psanders@ilstu.edu</span></a> Skype: paultlud<o:p></o:p></p>
<p class="MsoNormal"> Phone: Office: 309-452-7072 Mobile & WhatsApp: 309-531-4434<o:p></o:p></p>
<p class="MsoNormal">Exec. Dir. of Juntos Energy Solutions NFP Go to: <a href="http://www.juntosnfp.org/">
<span style="color:#0563C1">www.JuntosNFP.org</span></a> <o:p></o:p></p>
<p class="MsoNormal">Inventor of RoCC kilns for biochar and energy: See <a href="http://www.woodgas.com">
<span style="color:#0563C1">www.woodgas.com</span></a> <o:p></o:p></p>
<p class="MsoNormal">Author of “<i>A Capitalist Carol</i>” (free digital copies at
<a href="http://www.capitalism21.org/"><span style="color:#0563C1">www.capitalism21.org</span></a>)<o:p></o:p></p>
<p class="MsoNormal"> with pages 88 – 94 about solving the world crisis for clean cookstoves.
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> <a href="mailto:main@Biochar.groups.io">main@Biochar.groups.io</a> <<a href="mailto:main@Biochar.groups.io">main@Biochar.groups.io</a>>
<b>On Behalf Of </b>Ron Larson via groups.io<br>
<b>Sent:</b> Saturday, August 8, 2020 5:26 PM<br>
<b>To:</b> <a href="mailto:main@biochar.groups.io">main@biochar.groups.io</a>; Hugh McLaughlin <<a href="mailto:wastemin1@verizon.net">wastemin1@verizon.net</a>><br>
<b>Cc:</b> Kevin McLean > <<a href="mailto:info@sun24.solar">info@sun24.solar</a>><br>
<b>Subject:</b> Re: [Biochar] An example of the exotherm during pyrolysis<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hugh and list:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">See inserts. (I will respond separately to later messages - mainly from/with John Hofmeyer)<o:p></o:p></p>
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<p class="MsoNormal">On Aug 7, 2020, at 7:43 PM, Hugh McLaughlin via <a href="http://groups.io">
groups.io</a> <<a href="mailto:wastemin1=verizon.net@groups.io">wastemin1=verizon.net@groups.io</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">Hello List,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">I gave a webinar on July 23rd on the Greencarbonwebinar series where I discussed some concerns pertaining to the exotherm(s) that are lurking inside the nominally endothermic
heating of biomass. I decided to see if I could create a simple example of the magnitude of the phenomenon, since I have several laboratory scale reactors, the associated measurement instruments, and have run many such experiments over the years.<o:p></o:p></span></p>
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<p class="MsoNormal"><b>[RWL1: I listened to that webinar then and again today. I strongly recommend it to most everybody on this list. See </b> <a href="https://youtu.be/SsEKM1PaP4s?t=2772">https://youtu.be/SsEKM1PaP4s?t=2772</a>. The part on exotherms
is near the middle of your roughly 45 minutes.<b> (That whole series is wonderful.</b>). <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">Even I was surprised by the magnitude and rapidity of the phenomenon, as show by the two attached powerpoint slides. One slide is the yield as a function of temperature for
oxygen-free pyrolysis and the second is the lab data from a controlled heating of 627 grams of wood pellets from room temperature to 375C at 100 degrees per hour. The wood pellets were not dried before the experiment and the data shows the effect of removing
the 7 wt% moisture removed in a separate drying of the same wood pellets.<o:p></o:p></span></p>
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<p class="MsoNormal"><b>[RWL2; Re your first slide and throughout your talk - I conclude that it is now better to say that biochar is NOT charcoal - it is a different and superior product. Hmm. This is a very powerful sales-pitch conclusion that I’ve
been missing.</b><o:p></o:p></p>
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<p class="MsoNormal"><b>Re the second slide, I hope you can do a few more such experiments (you now being retired). Some fascinating results there that can probably be expanded with other parameters that relate better to cookstoves - where the pyrolysis might
be over in well less than an hour.</b><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b>I’ve added both your slides back in at the bottom.</b><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif"> <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">In summary, the exotherm raised the center of the reactor from 300C to 450C in less than 12 minutes, with a volatile generation of 40% of the initial biomass weight, which
is more than the weight of the final biochar exiting the reactor (33.3 wt% in this experiment). The surge in exiting volatiles was obvious, but was only 250 grams in the lab because the reactor only contained 627 grams of wood pellets initially.<o:p></o:p></span></p>
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<p class="MsoNormal"><b>[RWL3: Could you forward the weight loss data behind the 40% statistic (and any other data you took at the same time)? </b><o:p></o:p></p>
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<p class="MsoNormal"><b>Did you mean 40% loss in 12 minutes (or longer)? </b><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b>Do you feel most of the weight loss is
<u>always</u> exothermic? It seems the exothermacity stop was “sudden” - at about 450 C. I wonder what variation there is in that number with different feedstocks?</b><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">How this phenomenon manifests itself in any specific reactor geometry and size is difficult to predict, but it is clear that the exotherm is transversed as the pyrolysis temperature
exits torrefaction conditions and by the temperatures associated with acceptable biochar properties.<o:p></o:p></span></p>
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<p class="MsoNormal"><b>[RWL4: Re “<i>specific reactor geometry” - </i>that is exactly why I find this most interesting. I have been working with Kevin McLean (being cc’d) on cookstoves optimized for corncobs. Being so lightweight, the cobs disappear (too?)
quickly in a TLUD - suggesting the possible beneficial use of an associated retort. Having “violent” energy release in a retort is not what you want in a cook stove. </b><o:p></o:p></p>
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<p class="MsoNormal"><b>“Obviously”, this exothermic release is occurring in EVERY form of char-making. But it is well hidden in TLUD (and other) forms with a moving pyrolysis front. I have been assuming that most of the front movement was associated with
radiant energy associated with the front - but now guess that the radiant energy frequency is lower (thermal - not optical wavelengths).</b><o:p></o:p></p>
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<p class="MsoNormal"><b>I hope you or anyone working with char-making who has any ideas on how to design retorts to make exothermicity more of a benefit than a problem will chime in on how to best use retorts for cooking. (The main virtue being to not use
fossil fuels for cooking. Or disappearing biomass fuels. ).</b><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">As the saying goes, "Forewarned is forearmed". Please be careful when scaling up energy and vapor releases - because if the vessel cannot vent the pressure as it is generated,
the kinetics often accelerate and the risk of catastrophic failure rises rapidly.<o:p></o:p></span></p>
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<p class="MsoNormal"><b>[RWL5: I have yet to see anything very technical on retorts used in cooking - but I believe the obvious need to get the pyrolysis gases to a combustion region (presumably always into a TLUD and/or Rocket region) will mean Your warning
is NOT one needed for cookstoves employing a retort?</b><o:p></o:p></p>
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<p class="MsoNormal"><b>Not directly related to anything you have reported, but I believe pressure differences associated with the moving pyrolysis front are important. Any chance any of your data includes pressure changes? (I mean low pressures - not high
pressures.)</b><o:p></o:p></p>
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<p class="MsoNormal"><b>Should Kevin and I forget retorts as a help in furthering the replacement of fire woodd with corn cobs (now mostly left to rot in the field)?</b><o:p></o:p></p>
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<p class="MsoNormal"><b>Again, thanks for both the webinar (cite above) and yesterday’s additional more recent experimental result (below). </b><o:p></o:p></p>
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<p class="MsoNormal"><b> Thanks also for recommending the Green Carbon Joan Manya “book” you cited at the beginning of your webinar. I was surprised to find it is a freebie - at </b><a href="https://zenodo.org/record/3233733#.Xy8hchNKjGJ">https://zenodo.org/record/3233733#.Xy8hchNKjGJ</a> .
<b>I now have a lot to read.</b><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>One last thanks Is for giving so much credit in your webinar talk to the pioneering (both charcoal and biochar) work of Mike Antal. He has been missed; I wish I had known him better.</b><o:p></o:p></p>
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<p class="MsoNormal"><b>Ron</b><o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Verdana",sans-serif">- Hugh McLaughlin, PhD, PE<o:p></o:p></span></p>
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<p class="MsoNormal"><Pyrolysis exotherm and volatile generation example.pptx>. <o:p></o:p></p>
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