[Stoves] Fabricated Burn Barrel TLUDS

[Paul Anderson]

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:  psanders at ilstu.edu   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
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>
>
>
>
>
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