Dear Kobus and all,
Retort: When 50/50 inner and outer amounts of fuel as Kobus has
mentioned: the Outer burning XX kg yields zero biochar; Inside
retort yields 20 to 30& of XX kg, net of 10 to 15% of total fuel used.
(Note: charcoal yields from inside a retort of greater than 25 or 30%
indicate considerable volatile matter is in the charcoal, which is not
generally considered good for the plants/soils. Beware of charcoal that
is 40+% of original fuel weight. It will burn in a charcoal stove
probably with some limited smoke, but is not good as biochar.)
TLUD: One batch, expect about 20% yield by weight. Nearly double
the net weight output, and not needing double barrels, etc.
Fines are a result of size of feedstock. If making biochar, fines are
fine (pun intended). Or fines can be briquetted quite easily if sold to
the charcoal market.
Biggest problem I see with many attempts to make TLUD-style barrel-size
charcoal makers is the poor quality of the lid or top to allow in
secondary air that goes to the concentrator hole. If this sentence
does not make sense to someone, then that person has not studied the
basics of TLUD operation.
Users should start with small TLUDs (like McLaughlin's "1-G Toucan" out
of tincans - plans are on the web) so that they know that the TLUD fires
CAN and should be very clean burning. There is no reason to have
smoky TLUDs when using 200 liter barrels unless using wet fuel or not
yet adjusting the TLUD to the fuel at hand.
Paul
Paul S. Anderson, PhD aka "Dr TLUD"
Email: [email protected] Skype: paultlud Phone: +1-309-452-7072
Website: www.drtlud.com
On 9/30/2012 8:54 AM, Kobus Venter wrote:
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
Twitter: @vuthisahttps://twitter.com/vuthisa
Facebook:www.facebook.com/Vuthisa
LinkedIn:http://za.linkedin.com/in/vuthisa
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