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<DIV><BR><FONT face=Arial size=2><STRONG>Hi Arnt,</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>You ask:</STRONG></FONT></DIV><FONT
face=Arial size=2></FONT>
<DIV><BR><FONT face=Arial size=2><STRONG>> ..quick question: H2 needs how
much longer dwell time than CO?</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>For many years I was locked into H2
formation as only a temperature dependant disassociation, but this has been
shown to be incorrect by the continuous gas analysis we have been able to use
for the development programme in California. As we increased the
output over a range of bed depths, H2 dropped, while CO tended to
increase. You could always find a sweet spot for a chosen depth, but H2
formation lagged if you pulled harder.</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>If you increase the bed depths to increase
the contact/dwell time, even by say 25mm, the H2 will increase, but then so does
bed resistances. Time taken has to be nano seconds, but as you have
discovered, a good sneeze can help maintain the bed
porosity(:-)</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG></STRONG></FONT> </DIV>
<DIV><FONT face=Arial size=2><STRONG>There are many ways to skin this cat, but
the basics remain the same based on the experience so far. It would be great if
gas was only made at a fixed output, then variations of every type could be
controlled.</STRONG></FONT></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial size=2><STRONG>Doug Williams,</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2><STRONG>Fluidyne------</STRONG></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
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<DIV><FONT face=Arial size=2> </DIV>
<DIV><BR>> <BR>>> Question. Have you done continuous gas analysis from
start-up to shut<BR>>> down?<BR>>> <BR>>> Your question mark
in the equation suggests a combustible gas<BR>>> (~CH20), which would have
to survive the combustion /oxidation phase,<BR>>> or does this
vaporization take place as a portion of the char is<BR>>> consumed first
in oxidation,then reduction? Looking at these<BR>>> gasifying stove rings
burning as a blue gas, one might conclude that<BR>>> there is little if
any condensable tars present. If CH20 survives to<BR>>> be measured as a
gas, it's formation may be reflected in the H2<BR>>> variation if present,
depending on exactly where the H2 forms. Having<BR>>> said that, I have no
experience to draw from, to know if there is<BR>>> enough thermal inertia
after reduction to allow "other" reactions to<BR>>> take
place.<BR>>> <BR>>> As soon as we get some warm weather, I'll try to
measure the tar<BR>>> content from each, using my 2 kW generator and a 5
gal tar filter<BR>>> made from the charcoal. Comments,
suggestions?<BR>>> <BR>>> As you expect to capture tars in charcoal,
then I would want to have<BR>>> good control over the gas cooling/filter
temperatures, as the dew<BR>>> points of the fuel moisture content are
linked to carrying lighter<BR>>> pyrolysis gas/oils through filter media.
I'd want to know, especially<BR>>> the downdraft gasifier, if it had a
proven ability to make gas<BR>>> without or known condensing hydrocarbons,
using the fuels of the test.<BR>>> <BR>>> You also have the engine
to feed you lots of info as to gas<BR>>> condition, and I would use that
as a pre-test before you add the<BR>>> charcoal filter. A quick look under
the throttle butterfly could save<BR>>> you a lot of useless testing if
you see the sticky stuff in there! <BR>>> <BR>>> I'm sure you know
all these answers already Tom, but will watch for<BR>>> your postings of
the results.<BR>>> <BR>>> Regards,<BR>>> Doug
Williams,<BR>>> Fluidyne----<BR>>> <BR>>> <BR>> <BR>>
<BR>> -- <BR>> ..med vennlig hilsen = with Kind Regards from Arnt
Karlsen<BR>> ...with a number of polar bear hunters in his
ancestry...<BR>> Scenarios always come in sets of three: <BR>>
best case, worst case, and just in case.<BR>></FONT></DIV></BODY></HTML>