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<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'>Sorry, but the photos
were not attached. Crispin, please try again. Thanks, Agnes<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span lang=EN-GB
style='font-size:10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
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<p class=MsoNormal><b><font size=2 face=Tahoma><span style='font-size:10.0pt;
font-family:Tahoma;font-weight:bold'>Von:</span></font></b><font size=2
face=Tahoma><span style='font-size:10.0pt;font-family:Tahoma'>
stoves-bounces@lists.bioenergylists.org
[mailto:stoves-bounces@lists.bioenergylists.org] <b><span style='font-weight:
bold'>Im Auftrag von </span></b>Crispin Pemberton-Pigott<br>
<b><span style='font-weight:bold'>Gesendet:</span></b> Freitag, 25. November
2011 23:21<br>
<b><span style='font-weight:bold'>An:</span></b> '<st1:PersonName w:st="on">Discussion
of biomass cooking stoves</st1:PersonName>'<br>
<b><span style='font-weight:bold'>Betreff:</span></b> Re: [Stoves] Heat / cook
stove - proposed design</span></font><font size=3 face="Times New Roman"><span
style='font-size:12.0pt;font-family:"Times New Roman"'><o:p></o:p></span></font></p>
</div>
<p class=MsoNormal><font size=2 face=Calibri><span style='font-size:11.0pt'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>Dear Darren<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>This is coming along well.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>></span></font><span lang=EN-US>Some
photos are attached.<font color="#1f497d"><span style='color:#1F497D'><o:p></o:p></span></font></span></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>Got them, thanks.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span lang=EN-US style='font-size:
11.0pt'><br>
<font color="#1f497d"><span style='color:#1F497D'>></span></font>The door
and hatch are made and have fire rope seals. <font color="#1f497d"><span
style='color:#1F497D'><o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>Good move. The hopper should have no air
passing through it. There is a pyrolysis zone above and near the primary air
entrance, then a burning zone further to the left (back of the grate) then a
gas burning zone above the rear of the grate ascending into the vertical
chimney.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>></span></font><span lang=EN-US>I've
used a cast iron grate from an old coal stove that was the perfect size.<font
color="#1f497d"><span style='color:#1F497D'><o:p></o:p></span></font></span></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>It looks really. I think you should
expect to make two changes once you get going. One is to decrease the gap
between the grate and the ceramic bridge (we found 75mm is perfect for the fuel
we are burning) and to increase the 10 degree angle as a means for achieving
this. That means lifting up the front or near end of the grate. What would make
you want to try that would be excessive smoke caused by too much fuel burning
at once. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>We ran quite a number of tests with
different spacings like 65, 70, 75 and 85 and 90mm but all having 10 degrees of
slope. The 75 mm straight line distance was perfect. It gave an excess air
ratio of 80-120% and extraordinarily low PM values for much of the time.
Because your fuel is different you are going to have to do some hit and miss
too until you get a really clean flame about 15 minutes after ignition and
thereafter, no smoke. Hopefully it will perform as expected.<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 face=Calibri><span
lang=EN-US style='font-size:11.0pt'><br>
*At the moment all the secondary air is going in through some square section
pipe with an internal diameter of 20x20mm that enters at the rear of the
combustion chamber above the ceramic blocks. (shown as blue square in
stove2-7.jpg). Is this going to supply enough air or should I put a
similar sized secondary air inlet on the front of the stove also?<font
color="#1f497d"><span style='color:#1F497D'><o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>This si going to be a very difficult
question to answer without equipment. Suppose you have enough air but your
100mm grate gap is too big. It might incline you to provide more secondary air
when you really needed to reduce the burn rate. At some point, you have enough
power, so the air to match it is ‘X’ value. At a higher or lower
burn rate, you need a different amount. You are gonna tell us what you need! I
think the 20 x 20 may be too much but the fuel is different. The easy test is
to open and close it when there is only a little smoke. It should make very
little as it transitions from one firepower to another as it lights up. Somehow
the feedback from you hand closing it will tell you which way to take things.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>If you can’t see any need for it,
close it totally. It just add air with no effect other than to cool the output
gases. If you need it, leave it open. We have not found any need to adjust the
secondary volume when it is running. Most of the secondary air enters through
the far end (back) of the grate where there is less fuel.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span lang=EN-US style='font-size:
11.0pt'><br>
*Crispins GIZ design has an area where the combustion chamber tapers wider (an
expansion chamber?). I've drawn this in green in stove2-7.jpg . How
important is this? <font color="#1f497d"><span style='color:#1F497D'><o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>The expansion is important but not
critical. If you can, do it. Professor Lodoysamba found that filling the
combustion chamber with wood and top-lighting it provided immediate heat for
cooking, very low emissions and easy ignition (automatic) of the fuel under the
hopper. Very clever.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>When the fire reaches under the hopper,
he had to shake the grate to move fuel down onto the grate. That is all in
terms of attention.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color="#1f497d"
face=Calibri><span lang=EN-US style='font-size:11.0pt;color:#1F497D'>></span></font><span
lang=EN-US>What effect does it have on combustion? what would happen if I leave
them out?<font color="#1f497d"><span style='color:#1F497D'><o:p></o:p></span></font></span></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>The effect of the bricks/ceramic is to
improve the combustion by having hot walls. If you can’t get real
refractory bricks second hand, use the hardest clay face bring you can find. It
will last the longers in terms of off the shelf material.<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 face=Calibri><span
lang=EN-US style='font-size:11.0pt'><br>
<font color="#1f497d"><span style='color:#1F497D'>>…</span></font>Hopefully
I should finish and test fire it in the coming week.<font color="#1f497d"><span
style='color:#1F497D'><o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>Looking forward to more pictures and
your comments.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 color="#1f497d"
face=Calibri><span lang=EN-US style='font-size:11.0pt;color:#1F497D'>></span></font><span
lang=EN-US>I've attached a diagram of how I'm now planning to build the grate
and throat area. (I took the liberty of modifying the GIZ diagram Crispin
kindly sent to explain an appropriate layout) <font color="#1f497d"><span
style='color:#1F497D'><o:p></o:p></span></font></span></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>You construction matches the drawing.<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 face=Calibri><span
lang=EN-US style='font-size:11.0pt'><br>
As I'm only going to be burning wood and in my experience of wood stoves all
the wood burns to a light ash which would easily fall through the grate I am
planning to have a stationary grate. Am I making the wrong decision
here? <font color="#1f497d"><span style='color:#1F497D'><o:p></o:p></span></font></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>The grate gaps look large which will
create extra charcoal that might get snuffed in the ashes. Other than that it
is fine. If the grate turns out to be too ‘coarse’ you can drop in
a set of 12mm steel reinforcing bars welded into a grid. Works fine.<o:p></o:p></span></font></p>
<p class=MsoNormal style='margin-bottom:12.0pt'><font size=2 face=Calibri><span
lang=EN-US style='font-size:11.0pt'><br>
<font color="#1f497d"><span style='color:#1F497D'>></span></font>Hoping to
get it finished soon. Considering the number of people I've been
describing it to all year it would be good to also let them know how it
works!!! I've never seen anything like this in action - I'm thoroughly
intrigued. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>You are going to have to try it with
charcoal briquettes, wood pellets, wood, chopped up wood, coal and switchgrass
cubes if you want us all to be happy! Good luck.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>Regards<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'>Crispin<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color="#1f497d" face=Calibri><span lang=EN-US
style='font-size:11.0pt;color:#1F497D'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Calibri><span lang=EN-US style='font-size:
11.0pt'><o:p> </o:p></span></font></p>
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