<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Stoves:<div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Somehow my computer remembered an out-of-date "stoves” address.</div><div class=""><br class=""></div><div class="">Ron<br class=""><div><br class=""><blockquote type="cite" class=""><div class="">Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Ronal Larson <<a href="mailto:rongretlarson@comcast.net" class="">rongretlarson@comcast.net</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">Fwd: [Biochar] An example of the exotherm during pyrolysis</b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">August 8, 2020 at 4:39:34 PM MDT<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Discussion of biomass <<a href="mailto:stoves@listserv.repp.org" class="">stoves@listserv.repp.org</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif; color:rgba(0, 0, 0, 1.0);" class=""><b class="">Cc: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">Hugh McLaughlin <<a href="mailto:wastemin1@verizon.net" class="">wastemin1@verizon.net</a>>, "Kevin McLean >" <<a href="mailto:info@sun24.solar" class="">info@sun24.solar</a>><br class=""></span></div><br class=""><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">List: cc Hugh and Kevin<div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I just sent this to the biochar list - but much/most of it relates to char-making stoves. </div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Several useful cites below - all thanks to Hugh.. </div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Anyone able to help on the “retorts-as-parts-of-stoves” pmts of this message? More coming soon to this list on this corn cob topic.</div><div class=""><br class=""></div><div class="">Ron</div><div class=""><br class=""><div class=""><br class=""><blockquote type="cite" class=""><div class="">Begin forwarded message:</div><br class="Apple-interchange-newline"><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, "Helvetica Neue", Helvetica, sans-serif;" class=""><b class="">From: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">"Ron Larson" <<a href="mailto:rongretlarson@comcast.net" class="">rongretlarson@comcast.net</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, "Helvetica Neue", Helvetica, sans-serif;" class=""><b class="">Subject: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><b class="">Re: [Biochar] An example of the exotherm during pyrolysis</b><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, "Helvetica Neue", Helvetica, sans-serif;" class=""><b class="">Date: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">August 8, 2020 at 4:26:12 PM MDT<br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, "Helvetica Neue", Helvetica, sans-serif;" class=""><b class="">To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">"<a href="mailto:main@biochar.groups.io" class="">main@biochar.groups.io</a>" <<a href="mailto:main@Biochar.groups.io" class="">main@Biochar.groups.io</a>>, Hugh McLaughlin <<a href="mailto:wastemin1@verizon.net" class="">wastemin1@verizon.net</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, "Helvetica Neue", Helvetica, sans-serif;" class=""><b class="">Cc: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class="">"Kevin McLean >" <<a href="mailto:info@sun24.solar" class="">info@sun24.solar</a>><br class=""></span></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px;" class=""><span style="font-family: -webkit-system-font, "Helvetica Neue", Helvetica, sans-serif;" class=""><b class="">Reply-To: </b></span><span style="font-family: -webkit-system-font, Helvetica Neue, Helvetica, sans-serif;" class=""><a href="mailto:main@Biochar.groups.io" class="">main@Biochar.groups.io</a><br class=""></span></div><br class=""><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="">Hugh and list:</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>See inserts. (I will respond separately to later messages - mainly from/with John Hofmeyer)</div><div class=""><br class=""></div><div class=""><br class=""><blockquote type="cite" class=""><div class="">On Aug 7, 2020, at 7:43 PM, Hugh McLaughlin via <a href="http://groups.io/" class="">groups.io</a> <<a href="mailto:wastemin1=verizon.net@groups.io" class="">wastemin1=verizon.net@groups.io</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class=""><div class="yahoo-style-wrap" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"><div dir="ltr" data-setdir="false" class="">Hello List,</div><div dir="ltr" data-setdir="false" class=""><br class=""></div><div dir="ltr" data-setdir="false" class="">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.</div></div></div></div></blockquote><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span><b class="">[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" class="">https://youtu.be/SsEKM1PaP4s?t=2772</a>. The part on exotherms is near the middle of your roughly 45 minutes.<b class=""> (That whole series is wonderful.</b>). </div><blockquote type="cite" class=""><div class=""><div class=""><div class="yahoo-style-wrap" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"><div dir="ltr" data-setdir="false" class=""><br class=""></div><div dir="ltr" data-setdir="false" class="">Even I was surprised by the magnitude and rapidity of the phenomenon, as show by the two attached <span class="">powerpoint </span>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.</div></div></div></div></blockquote><span class="Apple-tab-span" style="white-space:pre"> </span><b class="">[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></div><div class=""><b class=""><br class=""></b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>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></div><div class=""><b class=""><br class=""></b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>I’ve added both your slides back in at the bottom.<br class=""></b><blockquote type="cite" class=""><div class=""><div class=""><div class="yahoo-style-wrap" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"><div dir="ltr" data-setdir="false" class=""> </div><div dir="ltr" data-setdir="false" class="">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.</div></div></div></div></blockquote><span class="Apple-tab-span" style="white-space:pre"> </span><b class="">[RWL3: Could you forward the weight loss data behind the 40% statistic (and any other data you took at the same time)? </b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Did you mean 40% loss in 12 minutes (or longer)? </b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Do you feel most of the weight loss is <u class="">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><br class=""><blockquote type="cite" class=""><div class=""><div class=""><div class="yahoo-style-wrap" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"><div dir="ltr" data-setdir="false" class=""><br class=""></div><div dir="ltr" data-setdir="false" class="">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.</div></div></div></div></blockquote><span class="Apple-tab-span" style="white-space:pre"> </span><b class="">[RWL4: Re “<i class="">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></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>“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></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>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></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span></b></div><div class=""><blockquote type="cite" class=""><div class=""><div class=""><div class="yahoo-style-wrap" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"><div dir="ltr" data-setdir="false" class="">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.<br class=""></div></div></div></div></blockquote><span class="Apple-tab-span" style="white-space:pre"> </span><b class="">[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></div><div class=""><b class=""><br class=""></b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span></b><b class="">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></div><div class=""><blockquote type="cite" class=""><div class=""><div class="yahoo-style-wrap" style="font-family: verdana, helvetica, sans-serif; font-size: 13px;"></div></div></blockquote></div><div class=""><br class=""></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>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></div><div class=""><b class=""><br class=""></b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>Again, thanks for both the webinar (cite above) and yesterday’s additional more recent experimental result (below). </b></div><div class=""><b class=""><br class=""></b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span> 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" class="">https://zenodo.org/record/3233733#.Xy8hchNKjGJ</a> . <b class="">I now have a lot to read.</b></div><div class=""><b class=""><br class=""></b></div><div class=""><b class=""><span class="Apple-tab-span" style="white-space:pre"> </span>One last thanks I</b><b class="">s 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></div><div class=""><b class=""><br class=""></b></div><div class=""><b class="">Ron</b></div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div class=""><div class=""><div class="yahoo-style-wrap" style="font-family:verdana, helvetica, sans-serif;font-size:13px;"><div class=""><br class=""></div><div dir="ltr" data-setdir="false" class="">- Hugh McLaughlin, PhD, PE<br class=""></div></div></div>
<span id="cid:f72f8811-f92f-cabd-f628-727f1f2cdaf2@yahoo.com" class=""><Pyrolysis exotherm and volatile generation example.pptx>. </span></div></blockquote></div></div></div><meta http-equiv="Content-Type" content="text/html; charset=us-ascii" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class=""></div></blockquote></div><br class=""></div></div>
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