[Stoves] Adding fuel to a TLUD

[Ray Menke]

Lanny,
Yes, but there is a certain technique.  The fuel should be added near
the end of the burn of the original fuel load, and using small cubes
or chunks works better than throwing in slivers of wood.  I made a
video two years ago showing how to make 32 pita breads using the
Anderson Champion TLUD (six inch diameter fuel chamber).
<http://www.youtube.com/watch?v=JOuoE2KAbQI>
By adding small hardwood cubes, the run time was extended to nearly 90
minutes.  If you add one or two cubes at a time into the hot bed of
charcoal, you get flame up to the bottom of the pan.  You will notice
I am using two cast iron pans to speed up the operation, and to reduce
the average heat level.  (Normal run time is about 30 min.)
Two weeks ago, I made another batch of pitas using a nine inch fuel
chamber TLUD of the same design, only scaled up.  This is a 7 kilowatt
version, mostly used to heating large pots of water, then regular
cooking/frying, followed by simmering.  I did not have to add any
fuel, but even with the primary air completely closed off, I had too
much heat, and actually blackened the first four pita breads (until I
got the temperature figured out).  (If you burn even a small spot, the
steam escapes, and the pita will not form the pocket.) The remaining
28 came out perfect, and I never needed to add any additional wood,
nor did I use the small computer fan.
Of course, once you start throwing chunks into the char at the bottom
of the TLUD, it is no longer a "proper" TLUD.
I now load my stoves with layers of fuel, with the larger cubes and
chunks at the bottom, over the grate, followed by really dry slivers
(almost scoopable) of wood, and then a couple of inches of cardboard
and paper slices that measure one inch by a quarter inch, with a small
dusting of charcoal fines, ignited with a few drops of alcohol.  Thus,
I get the layer of cardboard/paper char on top that glows while it
consumes any tar from the fuel beneath.  This works well, but as soon
as you throw in a one inch cube, the whole structure is destroyed, but
that is o.k., because most of the nasty tars are already consumed.
The Anderson design uses a small tube or chimney above the
restriction.  I bought a roll of high temperature ceramic wool
insulation, and now use it to wrap the tube so heat is not radiated
outwards from that tube.  When I made the video, I was not using that
insulation...but all of my stoves have been retrofitted.
Ray

On Fri, May 10, 2013 at 6:40 AM, Lanny Henson <lannych at bellsouth.net> wrote:
>
> Can you add fuel during the “burn” to a TLUD gasifier to boost the heat or
> extend cooking times.
>
> If a stove holds 1 can of fuel but the cooking task needs 1.5 cans of fuel
> say to boil a large pot of water.
>
> How can you make that work with a gasifier?
>
>
>
>
>
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-- 
Ray  Menke