[Stoves] big TLUD

Sat May 16 22:40:14 CDT 2015

Char-makers,

This good discussion on the Stoves Listserv is being shared with the 
Biochar Listserv.   Let discussions proceed on each and both and see 
what happens.

It is great to see so much discussion.   And Bill's video of his 350 
gallon unit is very informative.   We await info and photos of the 500 
gallon unit he is making now.

Bill wrote:
> the larger the diameter of the TLUD, the greater the chance that the 
> pyrolysis front will not reach the hearth in all areas at the same 
> time.  If this happens you risk overheating tha hearth if you wait for 
> all the fuel to pyrolyse and burn some of the biochar. 
I completely agree.  And when we report on our actual experience, please 
specify the diameter (which is probably more important that the volume).

Diameters:
1.   A 200 Liter (55 gal) drum or barrel is about 23 inches (58 cm) in 
diameter.   And that works rather well in the Jolly Roger Ovens (J-ROs) 
and similar units.

2.   From Bill's video, his unit 350 gallon (over 1000 liter) unit is 
quite tall and has a diameter about the same as at 55 gal drum. It is 
good to see that it works well.

3.  If I remember correctly, Alex's largest unit was 42 inch diameter 
(107 cm) and had problems with uneven descent of the Migratory Pyrolytic 
Front (MPF).   That matches well with Bill comment that is quoted above.

So, is Bill's 500 gal unit even taller but still "slender"?   And how 
well does it work?

An interesting question is about the possible favorable impact of having 
some of the following changes in the big TLUDs:

A.  Impact of a tapering the inside diameter in the lower section. But 
as I think more about that, I have my doubts if it will resolve the 
irregular MPF issue.

B.  impact of having sensors around the circumference of the TLUD at 
perhaps 1 meter vertical distances.   And if the temperature (indicating 
the MPF) is greater on one side too soon, EITHER
inject addition primary air via tuyers (nozzels) on the colder sides to 
hasten the MPF in those areas, OR
inject a bit of water into the area of the hot side to slow its movement 
a bit.

With serious char-making devices such as what Bill has, a relatively 
small cost would be the welding of some pipe nipples (each with a screw 
on cap) at the appropriate places for the air or water entries (B above) 
and where thermocouples could be inserted to check temperatures 
including in the center of the cylindrical column of fuel.

If anyone tries these ideas, please let us all know you progress and 
results.

Paul

Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
Email:  psanders at ilstu.edu
Skype: paultlud      Phone: +1-309-452-7072
Website:  www.drtlud.com

On 5/14/2015 8:20 PM, biocharFIRST . wrote:
> I don't know how big you can build a TLUD. However about three years 
> ago I built a 350 gallon TLUD that is working out very well, except 
> for the fact that we do not have a use for the sen gas where the TLUD 
> is now located at my home.  You can see a video at, 
> vhttps://www.youtube.com/watch?v=5Kfr4NRhJ0s.
>
> Currently we have almost completed a 500 gallon TLUD that is designed 
> to exhaust  all of the sen gas down a tube in the center of the tank 
> so the heat from the gas can easily be captured for various uses.
> r be uniformly dry, and the larger the diameter of the TLUD, the 
> greater the chance that the pyrolysis front will not reach the hearth 
> in all areas at the same time.  If this happens you risk overheating 
> tha hearth if you wait for all the fuel to pyrolyse and burn some of 
> the biochar.  If you shut off the primary before pyrolysis is complete 
> you will get some smoke and some biomass that is not completely 
> pyrolysed.
>
> On Thu, May 14, 2015 at 4:46 PM, Crispin Pemberton-Pigott 
> <crispinpigott at outlook.com <mailto:crispinpigott at outlook.com>> wrote:
>
>     AJH >Yes and/or premixing but why does burning rice hulls tend
>     more to the
>     blue flame?
>
>     Lower volatiles? The carbon/hydrogen ratio is not the same as
>     wood. Maybe
>     that helps.
>
>     Apparently the reactions can be shifted from CO to H2 by using
>     different
>     catalysts:
>     Crispin
>
>     From http://www.sciencedirect.com/science/article/pii/0141460786900727
>
>     Catalytic gasification of rice hull and other biomass. The general
>     effect of
>     catalyst.
>
>     Abstract:
>     Thermochemical decomposition and catalytic conversion of rice hull
>     and some
>     other cellulosic materials in a fluidized bed reactor containing
>     different
>     catalysts as the bed material were studied. The use of catalyst
>     invariably
>     gave gas yields above that of the non-catalyzed gasification
>     process and
>     also changed the product distribution according to the nature of the
>     catalyst. Generally, an acidic catalyst favored the formation of
>     carbon
>     monoxide and olefins while a supported-metal catalyst increased
>     the amounts
>     of hydrogen and carbon dioxide. Nickel catalyst yielded as much as 60%
>     hydrogen at a reaction temperature of 650°C. The gas yield and product
>     distribution are mainly decided by the properties of the catalyst
>     and less
>     by the properties of the biomass.
>
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