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<DIV>Paul,</DIV>
<DIV>I currently use wood ash as insulating material between the kalan and
combustion chamber of the eco-kalan (a rocket stove using wood, charcoal,
coconut husk, shell, fronds and other parts of the coconut tree). The
eco-kalan uses 75-85% less firewood and therefore a lot less ash is produced
compared to traditional kalans and other traditional cookstoves in Negros
Oriental, Philippines. A shortage in supply of ash is one factor
which affects sales of eco-kalan. I have
considered making an insulating material using a 50-50 mix by volume
of rice hull & clay in the form of pellets or bricks which would be broken
to pieces after firing. I would fire the pellets or the bricks along with
the eco-kalans up to 900 degrees Celsius. Will there be significant
formation of cristobalite under these conditions? Would handling the fired
pellets or the breaking of the bricks be a health hazard? Thanks,</DIV>
<DIV> </DIV>
<DIV>Rebecca Vermeer</DIV>
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<DIV style="font-color: black"><B>From:</B> <A title=paul.olivier@esrla.com
href="mailto:paul.olivier@esrla.com">Paul Olivier</A> </DIV>
<DIV><B>Sent:</B> Friday, June 14, 2013 12:07 AM</DIV>
<DIV><B>To:</B> <A title=ravermeer@telus.net
href="mailto:ravermeer@telus.net">Rebecca A. Vermeer</A> </DIV>
<DIV><B>Cc:</B> <A title=jonnygms@gmail.com href="mailto:jonnygms@gmail.com">Jon
Anderson</A> ; <A title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">stoves@lists.bioenergylists.org</A>
; <A title=larryw@gotsky.com href="mailto:larryw@gotsky.com">larry winiarski</A>
</DIV>
<DIV><B>Subject:</B> Re: Fw: [Stoves] : Re: Insulation and stove
life</DIV></DIV></DIV>
<DIV> </DIV></DIV>
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<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">
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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-SIZE: small; FONT-FAMILY: 'Calibri'; FONT-WEIGHT: normal; FONT-STYLE: normal; TEXT-DECORATION: none; DISPLAY: inline"><B>From:</B>
<A title=paul.olivier@esrla.com href="mailto:paul.olivier@esrla.com"
target=_blank>Paul Olivier</A> </DIV>
<DIV style="FONT: 10pt tahoma">
<DIV style="BACKGROUND: #f5f5f5">
<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>
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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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clear=all><BR>-- <BR>Paul A. Olivier PhD<BR>26/5 Phu Dong Thien
Vuong<BR>Dalat<BR>Vietnam<BR><BR>Louisiana telephone: 1-337-447-4124 (rings
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