[Stoves] Fabricated Burn Barrel TLUDS

[Tom Miles]

Kobus,

 

The most common use of fines that we see is to inoculate them with compost
tea or another nutrient source, or to combine them in, or with, compost to
make a retail garden product. 

 

Tom 

 

From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Kobus Venter
Sent: Sunday, September 30, 2012 6:55 AM
To: stoves at lists.bioenergylists.org
Subject: Re: [Stoves] Fabricated Burn Barrel TLUDS

 

Tom, Paul, Dan and others, 

 

I have gone away a bit from the TLUD principle as I started from a very
polluting open top burn approach and using feedstock that is not uniform in
particle size. Very wasteful, and as in Dan's case I ended up with a lot of
fines (http://vuthisa.files.wordpress.com/2012/09/img00177.jpg). The only
cost effective way that I could improve emissions of the Transportable Metal
Kiln was to convert it into a retort, by using the heat from the
conventional burn to heat the inner retorts. The flow rate of the air
through the outer burn will be high, probably around 1.5 m3/sec and the
quantity of feedstock necessary to provide the heat to the inner retorts
before the reaction becomes exothermic will probably match the closely
packed feedstock volumetrically inside the 3 x 55 gal drums, which will
ultimately yield the biochar. The burn is seen as successful only if ash
remains in the outer vessel and all the biomass inside the 55 gal drums is
pyrolysed.  I don't need a TLUD type flow rate to ensure complete
carbonisation, but the consumed wood in the outer drum has to be included in
the overall yield percentage calculation. The addition of a conical lid and
chimney (much akin to the New Hampshire metal kiln design) has increased the
draft needed to vent emissions. In the conventional open drum burn I would
place ±550 kg feedstock and end up with 120 kg charcoal, but 50% will be
fines.  In the 3-drum retort I would probably also use 550 kg but end up
with ???? I would not like to venture an answer at this early stage, but
hopefully end up with more than just 60 kg of biochar. The principal
advantages of my three drum retort should be the 25% yield of char from the
retort contents, coupled with the ability to use lower quality fuel as the
starter fuel (outside the drum) and the self-stopping of the retort design
(better safety, no need fro water), and the self-running aspect (light it
and step back).   

 

http://vuthisa.files.wordpress.com/2012/09/slits_drum.jpg

http://vuthisa.files.wordpress.com/2012/09/dscf335.jpg

http://vuthisa.files.wordpress.com/2012/09/branches_lid-removed2.png

http://vuthisa.files.wordpress.com/2012/09/bottom.jpg

 

Regards

 

Kobus

 

****************************************************************************
****

AD, Paul, Kobus and others. Many thanks for the suggestions. 

What is the largest practical size (kg fuel/hr, kW) for a single TLUD with a
clean stack for heat recovery? There must be a limit to the air penetration
to get a clean gas burn form a natural draft stack or even a fan driven
TLUD. 

Tom 

 

 

http://www.vuthisa.com <http://www.vuthisa.com/> 
Twitter: @vuthisa https://twitter.com/vuthisa
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LinkedIn: http://za.linkedin.com/in/vuthisa

 

 

 

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