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<DIV><FONT face=Arial>Dear Crispin</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>I can think of two possibilities for the possible weight
gain:</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>1: If there was backdraft, as a result of the windy
conditions, it might be possible that particles of char or creosote fell from
the chimney, or were blown back, to the stove system, creating an increase in
weight of the stove system. This material then burned off. Note that the weight
at about 2815 is the same as at the very end of the chart, where the red line
continues past 6567</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>2: The oxygen that was picked up would be not only as
oxygen, but as CO2. What might have happened is that is that the ash, containing
FeO could easily pick up oxygen and become oxidized to Fe3O4, and limestone
components in the ash could have been calcined to CaO, which could easily react
with CO2 from the atmosphere, to "airslake" back to CaCO3. The "jiggle in the
weight" may be a result of "local fire" re-calcining" the lime fraction, or
"re-reducing the iron components.</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Any likelihood that either of these guesses might be
accurate?</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Best wishes,</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Kevin</FONT></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=crispinpigott@gmail.com href="mailto:crispinpigott@gmail.com">Crispin
Pemberton-Pigott</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">'Discussion of biomass cooking
stoves'</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, February 25, 2013 5:59
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Stoves] combustion of char
-- spontaneous and dangerous</DIV>
<DIV><BR></DIV>
<DIV class=WordSection1>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US">Dear
Kevin<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US">That
is indeed a refuelling. The initial drop is the coal burning. Then it is
refuelled (jump up in mass) then it burns down again and eventually goes out
completely after some hours. <o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US">The
surprises are the shaking of the stove scale by the wind in the night, and
then the increase in the system mass. The curve moves up and down in a manner
surprisingly similar to the mass change charts of Battacharyya. This was a
traditional stove and the burning of coal near the edges of the chamber is not
all perfect. How much O2 can char pick up in a few hours? Is this
real or an artifact of the wind?<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US">Regards<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US">Crispin<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt; mso-fareast-language: EN-US"><o:p> </o:p></SPAN></P>
<P class=MsoNormal><o:p> </o:p></P>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">Dear
Crispin</SPAN><SPAN style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="COLOR: windowtext"> <o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">I don't
understand the graph...</SPAN><SPAN
style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">1: What are the
units of the vertical scale? (Is it Grams weight?)</SPAN><SPAN
style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">2: The weight (?)
gain is virtually instantaneous.</SPAN><SPAN
style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="COLOR: windowtext"> <o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">Presuming the
vertical axis is the weight of the stove system and contents in grams, the
instantaneous system weight gain would be 108,400 less 103,800 = 4,600
grams.</SPAN><SPAN style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="COLOR: windowtext"> <o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">What could
possibly explain such a large and instantaneous weight gain? Did someone
simply put more wood or coal on the fire?</SPAN><SPAN
style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="COLOR: windowtext"> <o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">Best
wishes,</SPAN><SPAN style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="COLOR: windowtext"> <o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext">Kevin</SPAN><SPAN
style="COLOR: windowtext"><o:p></o:p></SPAN></P></DIV>
<BLOCKQUOTE
style="BORDER-BOTTOM: medium none; BORDER-LEFT: black 1.5pt solid; PADDING-BOTTOM: 0mm; MARGIN: 5pt 0mm 5pt 3.75pt; PADDING-LEFT: 4pt; PADDING-RIGHT: 0mm; BORDER-TOP: medium none; BORDER-RIGHT: medium none; PADDING-TOP: 0mm">
<DIV>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">-----
Original Message ----- <o:p></o:p></SPAN></P></DIV>
<DIV>
<P style="BACKGROUND: #e4e4e4" class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">From:</SPAN></B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
<A title=crispinpigott@gmail.com
href="mailto:crispinpigott@gmail.com">Crispin Pemberton-Pigott</A>
<o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">To:</SPAN></B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
<A title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">'Discussion of biomass cooking
stoves'</A> <o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">Sent:</SPAN></B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
Monday, February 25, 2013 2:45 PM<o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">Subject:</SPAN></B><SPAN
style="FONT-FAMILY: 'Arial','sans-serif'; COLOR: windowtext; FONT-SIZE: 10pt">
Re: [Stoves] combustion of char -- spontaneous and
dangerous<o:p></o:p></SPAN></P></DIV>
<DIV>
<P class=MsoNormal><SPAN
style="COLOR: windowtext"><o:p> </o:p></SPAN></P></DIV><PRE><SPAN style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt" lang=EN-US>Dear Friends<o:p></o:p></SPAN></PRE><PRE><SPAN style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt" lang=EN-US><o:p> </o:p></SPAN></PRE><PRE><SPAN style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt" lang=EN-US>Here is a mass profile, raw and smoothed with 21 point simple averaging (minus 1000 to pull it down so you can see it).<o:p></o:p></SPAN></PRE><PRE><SPAN style="FONT-FAMILY: 'Calibri','sans-serif'; COLOR: #1f497d; FONT-SIZE: 11pt" lang=EN-US><o:p> </o:p></SPAN></PRE></BLOCKQUOTE></DIV>
<P>
<HR>
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