Tom,
I (and many others, for sure) appreciate your explanations (below).
One question: The lignin is present as the celluloses are changed to
gas. And the lignin BECOMES char. Please discuss that chemistry of
lignin becoming char. What is happening?
Comment: Looking at the gases that are coming out of TLUDs (that is,
the gases BEFORE they get to any combustor), they appear to be (seem to
be, give the impression of, possibly are) loaded with the stuff that
would clog engines. So I need a chemist's explanation of why those
gases have advantages over those from the Imbert, etc.
Still learning,
Paul
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: [email protected]
Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 2/7/2014 4:36 PM, Tom Reed wrote:
Evan
Good question, "Why do TLUDs (Toplit updraft combustors) exclude hemicellulose and
lignin?" First, I think they do burn the hemicellulose along with the cellulose. Maybe I
should have said "celluloses". (The hemicellulose is only a few % of wood! and is even
more volatile than the cellulose. )
You are correct. The cellulose (and hemicellulose) become volatile at about
330C,
C6H10O5 + 1/2 O2 ===> 6 CO + 5 H2 Delta H = (2829 - 3080) -260
ENDOTHERMICl
and generates the gas we see burning in the match (for instance). The same
temperature converts the lignin to charcoal, and if there is a choice between
cellulose (in the next lower layer for TLUDS) and this charcoal, the flame
moves to the cellulose gas from the next layer, leaving the charcoal behind,
protected by the oxygen free gas left from cellulose combustion.
The WWII (Imbert) gasifiers injected air below the unburned wood and above the
charcoal as it formed. This keeps the air in balance, since it too much
charcoal was momentarily consumed, more wood fell in front of the air nozzles
and balance was restored.
<><><>
Today we have an alternate use for the charcoal, Biochar, to improve soil
fertility and reduce global warming, so by consuming only the celluloses, we
produce ~ 20% charcoal from our wood supply. So the TLUD gasifier is a simple
alternative to Imbert. It also produces a gas that is easier to clean for
engine use.
It is surprising that, with all the dependence on wood burning for heat, this
wasn't discovered centuries earlier. If you make a vertical pile of fireplace
logs and light ON TOP, they will burn down at a steady rate, the embers of each
layer lighting the next layer, no matter how high the pile.
Try it, and send comments.
Tom Reed
Dr. Thomas B Reed
280 Hardwick Rd
Barre, MA 01005
508 353 7841
On Feb 7, 2014, at 4:00 PM, Evan Marks <[email protected]> wrote:
A question to Tom Reed:
Just wanted to get some clarity on the statment that TLUDs only burn cellulose.
If we are contrasting for instance WWII sytems and TLUDs, and therefore
limitation to only the cellulose fraction, is the primary difference
temperature? Why do TLUDs exclude hemicellulose and lignin? Is the cellulose
fraction equivalent to the volatile fraction?
Thanks, -EM
Dear Tom Miles and all
WWII gasification converted all the fuel into a low quality (150Btu/scf) gas
that required considerable cleanup. Before use in engines.
Now that we recognize the value of biochar as
O. A soil amendment
O. Reducing global warming
a second option is more attractive.
In the TLUD stove and larger (eg 33 gal garbage can) only the cellulose burns,
giving a cleaner gas
C6H10O5 + 1/2 O2 ===>
6O + 5 H2
Plus. biochar for addition to the soil.
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