[Gasification] Gasification, TLUDs and Biochar

Tom Miles tmiles at trmiles.com
Tue May 14 23:03:57 CDT 2013

This should be of interest to biochar and gasification enthusiasts.

Thanks Tom Reed.  

Tom Miles

-----Original Message-----
From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Thomas Reed
Sent: Tuesday, May 14, 2013 8:55 PM
To: stoves at lists.bioenergylists.org

Dear Gasologist

We should all distinguish clearly when discussing gasification between 

O Total gasification (eg an Imbert gasifier) that converts typically 98% ot
the wood to WoodGas

O Pyrolytic Gasification (TLUD and larger) which primarily  gasifies the
cellulose and pyrolyses the lignin to ~20% charcoal


The smoke from a TLUD stove will leave a deposit on a cold steel plate.  I
was interested in finding out how much "tar" was in the TLUD combustible gas
before it is burned.  

I measured the "tar" production from a TLUD stove by putting a 4" galvanized
elbow (wrapped in wetted towels) in the stove, and a 4 ft length of
galvanized pipe followed by another elbow and chimney.

Instead of the tarry deposit I expected, I obtained about 1% of a brown
powdery deposit that was quite dry to the touch.  

I now wish I had saved it and analyzed it further.   But I suspect a similar
experiment on the Imbert gas would give a much higher "Tar" content,
originating mostly from the lignin.  


The charcoal resulting from the TLUD is generally a bonus, depending whether
you have a use for it.  The temperature of the flaming pyrolysis below the
surface of the TLUD stove is between 500 and 700 C (measured with a Cr-Al
thermocouple).  For this reason, the charcoal produced is much more
absorptive than commercial (<450 C) charcoal.  

This spring I am doing some planting tests on TLUD charcoal vs commercial
charcoal.  I'll report results.  

Onward to the future of charcoal...

Tom Reed

Dr. Thomas B Reed 
Tombreed2010 at gmail.com

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