<p>Rebecca,</p>
<p>If we directly burn river hulls, there should be a lot of cristobalite formed. If we gasify, this problem should be minimized, provided channeling does not occur. Also there might be cristobalite in the particulate matter in the combustion gases. With rice hull pellets in a TLUD we have a lot less channeling, and a lot less particulate matter. Therefore the rice hull pellet becomes an attractive fuel for these and many other reasons.</p>
<p>Thanks.<br>
Paul Olivier</p>
<div class="gmail_quote">On Jun 14, 2013 1:44 PM, "Rebecca A. Vermeer" <<a href="mailto:ravermeer@telus.net">ravermeer@telus.net</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div>Hello Paul,</div>
<div>Larry just told me that the silica content of rice hull ash is over
90%. At the ETHOS 2013 Conference, I saw a TURBO stove developed in the
Philippines which used rice hull for fuel. Given your comment below
regarding cristobalite “which is a nasty carcinogen” and severely hazardous to
human health (see link below), would you recommend the use of rice hull as
a household fuel for cookstoves? </div>
<div> </div>
<div>Rebecca Vermeer</div>
<div> </div>
<div>CRISTOBALITE LINK:</div>
<div><a title="http://nj.gov/health/eoh/rtkweb/documents/fs/1657.pdf" href="http://nj.gov/health/eoh/rtkweb/documents/fs/1657.pdf" target="_blank">http://nj.gov/health/eoh/rtkweb/documents/fs/1657.pdf</a></div>
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<div style="font-style:normal;font-size:small;display:inline;text-decoration:none;font-family:'Calibri';font-weight:normal"><b>From:</b>
<a title="paul.olivier@esrla.com" href="mailto:paul.olivier@esrla.com" target="_blank">Paul
Olivier</a> </div>
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<div><b>Sent:</b> Wednesday, June 12, 2013 12:01 AM</div>
<div><b>To:</b> <a title="stoves@lists.bioenergylists.org" href="mailto:stoves@lists.bioenergylists.org" target="_blank">Discussion of biomass cooking
stoves</a> </div>
<div><b>Subject:</b> Re: [Stoves] : Re: Insulation and stove
life</div></div></div>
<div> </div></div>
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<div>Paal,<br><br></div>One thing I look for on my burner is that all burner
holes support a flame throughout the process. If channeling occurs during the
process or if char is being burned as the process comes to a close, then one can
see burner holes that do not support a flame. This means that CO2 is being
discharged from the burner holes, and of course CO2 does not burn. When CO2 is
formed, this represents a big inefficiency, since combustion takes place far
below the pot. When this happens the sides of the reactor can easily turn red
hot and melt. I do not know how it is possible to spot the presence of CO2 if
the top of the reactor stays open and does not have a lid with burner
holes.<br><br></div>If one turns up the fan a bit too high resulting in
channeling, it can happen that only a few holes (among a total of 80 in my case)
do not support a flame. If I turn the fan down a bit and shake the reactor, this
problem is immediately corrected. Also the effect of the presence of CO2 can be
spotted by the cook in another way. The distribution of heat to the pan is not
even.<br><br></div>
<div>Also many of the positive characteristics of biochar are lost when biochar
is combusted and is reduced to ash. The combustion of biomass and biochar takes
place when channeling occurs, and the combustion of biochar takes place if the
fan is not turned off at the end of the process. Rice hull ash and rice hill
biochar are not at all the same thing when it comes to growing plants. <font color="#ff0000">Also rice hull ash can easily contain cristobalite, which is a
nasty carcinogen. Under ordinary conditions, no farmer should be handling this
stuff.<br></font></div>
<div><font color="#00ff00"></font> </div>Thanks.<br></div>Paul<br>
<div class="gmail_extra"><br><br>
<div class="gmail_quote">On Wed, Jun 12, 2013 at 1:06 PM, Paal Wendelbo <span dir="ltr"><<a href="mailto:paaw@online.no" target="_blank">paaw@online.no</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="PADDING-LEFT:1ex;MARGIN:0px 0px 0px 0.8ex;BORDER-LEFT:#ccc 1px solid">
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<p class="MsoNormal" style="MARGIN:0cm 0cm 10pt;LINE-HEIGHT:13pt"><span lang="EN-US"><font style="FONT-SIZE:11pt">Ron</font></span></p>
<p class="MsoNormal" style="MARGIN:0cm 0cm 10pt;LINE-HEIGHT:13pt"><span lang="EN-US"><font style="FONT-SIZE:11pt">By end of flame the color of the char
is red to yellow, that indicate a temperature of 700 to 800 ˚C and when there
is no smoke, complete combustion has taken place. Is that not good for
biochar?</font></span></p>
<p class="MsoNormal" style="MARGIN:0cm 0cm 10pt;LINE-HEIGHT:13pt"><span lang="EN-US"><font style="FONT-SIZE:11pt">Regards Paal
W</font></span></p></div></div></div><br>_______________________________________________<br>Stoves
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