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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='color:#1F497D'>Crispin,<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>If you can keep peak temperatures below about 750 C then you can keep a larger fraction of the K in the char. We have done this with staged combustion in a variety of straw burners. It is now done commercially in large scale straw burning power plants in Denmark, Spain and the UK. <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>That's the beauty of biochar from crop residues - low peak temperature conversion to retain nutrients - but we have a wide variety of reactors, including stove types, to deal with. It would be interesting to see an elemental analysis of the principal ash components of the fuel and char from the TLUDs to see what elements are retained. I haven't seen a proximate, ultimate, Btu (HHV) and ash elemental analysis of any TLUD fuel. <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D'>Tom <o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D'><o:p> </o:p></span></p><div><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>Crispin Pemberton-Pigott<br><b>Sent:</b> Sunday, October 16, 2011 2:37 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></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoPlainText><span lang=EN-CA>Dear Friends<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>I am bringing to mind that these high temperatures and the presence of at least two fluxes were discussed when we were looking at making ceramic stove components. The same principles apply: if there are fluxes (CL, K) in the clay (ash) Si melts at a lower temperature. Alex found to his dismay this is pretty easy to do with a large scale grass burner.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Roger Samson, to his credit, found out how to get the Cl and K out of the grass and dramatically reduce the problem. When we speak of 'char' and at the same time 'biomass' and 'wood', it would do us well to keep in mind the very different result obtained when heating them to 900-950 C. One is going to produce fused ash immediately and the other is hardly going to produce any at all.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>With ceramics, it is common to <i>add</i> K to reduce the melting temperature. It seems that with combustion, we want it <i>out</i> because of the problems caused.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Regards<br>Crispin<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>+++++<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Paul,<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA> Attached is minimalist, two points, graph showing potassium volatility beginning at 400C with a ~37% loss at 800C.<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Courtesy of Preto and Hrbek;<o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><a href="http://www.biochar.ca/files/Can%20Biochar%20Initiative%20Preto%20Dec08.pdf"><span style='color:windowtext;text-decoration:none'>http://www.biochar.ca/files/Can%20Biochar%20Initiative%20Preto%20Dec08.pdf</span></a><o:p></o:p></span></p><p class=MsoPlainText><span lang=EN-CA><o:p> </o:p></span></p><p class=MsoPlainText><span lang=EN-CA>Alex<o:p></o:p></span></p></div></body></html>