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<DIV><FONT size=2 face=Arial>Dear Jim</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Interesting thoughts!</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>What are your thoughts on the optimum moisture
content of biomass feed to a gasifier? On the one hand, with low fuel moisture
content, there is a low endothermic load on teh reaction. On the other hand, a
high moisture content could yield greater hydrogen content in the output
gas.</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>To take things to the limit, what are your thoughts
on feeding a gasifier with torrified wood?</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Thanks!</FONT></DIV>
<DIV> </DIV>
<DIV><FONT size=2 face=Arial>Kevin</FONT> </DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=jim@allpowerlabs.org href="mailto:jim@allpowerlabs.org">jim mason</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=gasification@bioenergylists.org
href="mailto:gasification@bioenergylists.org">gasification@bioenergylists.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Monday, October 18, 2010 2:08
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [Gasification] the most
important thing (quite possibly) i'velearned to date</DIV>
<DIV><BR></DIV><BR><BR>there are many variables to move around in a gasifier,
and all of them are<BR>important. but once the basics are in order, i'm coming
to the conclusion that<BR>the most impactful thing one can do/add/fix to the
basic imbert design is to use <BR>the ic engine exhaust to heat the incoming
fuel.<BR><BR>no, i don't have any numbers on this yet (we hope to get these
soon), but the<BR>anecdotal experiences keep piling up. the biggest
flexibility gains i'm finding<BR>both in poor fuel shape/size and moisture
tolerance, as well as gas turndown ratio, <BR>are from the ic exhaust heat
exchanger. on our rig, this is called the pyrocoil. other<BR>rigs call this
something else.<BR><BR>this is not terribly surprising. the ic exhaust is the
biggest waste heat<BR>source we have around a gasifier. in principle, the ic
exhaust has about about<BR>3x or 4x the heat available as the outgoing syngas.
the incoming fuel similarly<BR>has much more heating capacity than the
incoming air (the multiple i forget at<BR>the moment, but i do know the
incoming air can only take up about 1/2 of the<BR>heat available in the
outgoing syngas).<BR><BR>also, the ic exhaust is much hotter than the outgoing
syngas after preheating<BR>the incoming air. thus you can use the ic exhaust
to do much more than dry the<BR>fuel. you can it to drive the fuel through
pyrolysis, and really, get it up to<BR>about 4-500c before it falls into the
hearth proper. this is a big difference<BR>from the typical situation of still
moist fuel falling into the hearth.<BR><BR>not only can you use the ic exhaust
to add a very significant amount of heat to<BR>the system, you can also use it
to change the character of pyrolysis in the<BR>reactor. a typical downdraft
has very high temp short residence time pyrolysis<BR>right on top of the
nozzles. this high temp pyrolysis optimizes the creation of<BR>teritary tars,
or refractory tars, which are difficult to crack again (given<BR>lots of
double carbon bonds). if you externally drive pyrolysis at lower temp<BR>over
longer time, you get more primary and secondary tars, which are easier
to<BR>crack downstream (fewer double carbon bonds). this seems to allow
hearth<BR>conditions to be less perfect and still get good gas
out.<BR><BR>using ic exhaust to heat incoming fuel is not a complete get out
of jail free<BR>card. but to me it seems the most impactful new thing one can
do on these rigs.<BR>it seems to have more of an impact than any other single
thing we've done to<BR>date on the gek.<BR><BR>yes, all of it is important,
and all of it should be tended to, but the above is<BR>my current vote for the
biggest bang for the effort. hopefully we can get some<BR>proper numbers on
this soon (and prove or disprove the above
conjecture).<BR><BR>jim<BR><BR><BR><BR><BR><BR><BR>------------------------------------------------------------------------------<BR>Jim
Mason<BR>Website: <A
href="http://www.whatiamupto.com">http://www.whatiamupto.com</A><BR>Current
Projects: <BR> - Gasifier Experimenters Kit (the GEK): <A
href="http://www.gekgasifier.com">http://www.gekgasifier.com</A><BR>
- Escape from Berkeley alt fuels vehicle race: <A
href="http://www.escapefromberkeley.com">www.escapefromberkeley.com</A><BR>
- ALL Power Labs on Twitter: <A
href="http://twitter.com/allpowerlabs">http://twitter.com/allpowerlabs</A><BR>
- Shipyard Announce list: <A
href="http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com">http://lists.spaceship.com/listinfo.cgi/icp-spaceship.com</A><BR>
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