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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Paul,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The coffee husks I have seen are paper thin. Is your fuel like that or thicker? If it is think then it will “flash” pyrolyze. The rice husks would provide structure and could dampen the evolution or loss of nutrients. We have seen silica absorb potassium in the gas stream. So I don’t think that you can assume that you will lose it all even if your raw fuel reaches peak temperatures of 800-1000 C. The char probablu sees 800-900C. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Tom<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><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"'> stoves-bounces@lists.bioenergylists.org [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Paul Olivier<br><b>Sent:</b> Sunday, October 16, 2011 1:23 PM<br><b>To:</b> Discussion of biomass cooking stoves<br><b>Subject:</b> Re: [Stoves] why does coffee husk biochar smell like urine?<o:p></o:p></span></p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Alex,<br><br>Thanks so much for this graph.<br><br>Alexis Belonio says that the temperature within his gasifiers on rice hulls reaches 1,000 C.<br>If this is true in the case of rice hulls, <br>then the temperature within the reactor in the case of coffee husks is a good deal higher.<br>If this is true, a lot of the K is lost in the coffee husk gas.<br><br>Coffee husks biochar has a moment at which it swells or expands during gasification.<br>The volume of char actually increases within the reactor.<br>But if I shake the reactor during the process, the volume of char decreases enormously.<br>If left unshaken, large cracks appear in the char, and the char forms clumps.<br><br>When I added rice hulls to the coffee husks on the one occasion,<br>cracks did not appear in the biochar within the reactor, and the burn was far more uniform.<br>The production of soot decreased a lot.<br><br>A few months ago, I put coffee husks in a large pan and attempted to torrefy them using gasifier heat.<br>During this process, a lot of fumes were produced, and the coffee husks lost their oily aspect.<br>When I gasified these "torrefied" husks, the flame shifted from orange to a color in between orange and blue.<br><br>This opens up the possibility of torrefying the coffee husks to produce acetic acid and other compounds.<br>Just as we torrefy the coffee bean, we would torrefy the husk.<br>This would leave behind a solid that would no longer absorb water,<br>as well as a solid that would thermally decompose at high temperatures in a superior manner.<br>I have no idea if this makes sense.<br><br>Thanks.<br>Paul<br><br><o:p></o:p></p><div><p class=MsoNormal>On Sun, Oct 16, 2011 at 7:58 PM, Alex English <<a href="mailto:english@kingston.net">english@kingston.net</a>> wrote:<o:p></o:p></p><p class=MsoNormal>Paul,<br> Attached is minimalist, two points, graph showing potassium volatility beginning at 400C with a ~37% loss at 800C.<br>Courtesy of Preto and Hrbek;<br><a href="http://www.biochar.ca/files/Can%20Biochar%20Initiative%20Preto%20Dec08.pdf" target="_blank">http://www.biochar.ca/files/Can%20Biochar%20Initiative%20Preto%20Dec08.pdf</a><br><span style='color:#888888'><br>Alex</span><o:p></o:p></p><div><div><p class=MsoNormal><br><br><br>On 16/10/2011 2:25 AM, Paul Olivier wrote:<o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>Tom,<br><br>But the temperature in the reactor is much higher than 350 C.<br>I have seen a sort of clinker in the biochar if I do not turn the fan off at the end of a batch.<br>At what temperature does the vaporization of K take place?<br><br>Paul<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></div><p class=MsoNormal style='margin-bottom:12.0pt'><br>_______________________________________________<br>Stoves mailing list<br><br>to Send a Message to the list, use the email address<br><a href="mailto:stoves@lists.bioenergylists.org">stoves@lists.bioenergylists.org</a><br><br>to UNSUBSCRIBE or Change your List Settings use the web page<br><a href="http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org" target="_blank">http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org</a><br><br>for more Biomass Cooking Stoves, News and Information see our web site:<br><a href="http://www.bioenergylists.org/" target="_blank">http://www.bioenergylists.org/</a><br><br><o:p></o:p></p></div><p class=MsoNormal><br><br clear=all><br>-- <br>Paul A. Olivier PhD<br>27C Pham Hong Thai Street<br>Dalat<br>Vietnam<br><br>Louisiana telephone: 1-337-447-4124 (rings Vietnam)<br>Mobile: 090-694-1573 (in Vietnam)<br>Skype address: Xpolivier<br><a href="http://www.esrla.com/" target="_blank">http://www.esrla.com/</a><o:p></o:p></p></div></body></html>