[Stoves] Changing rate of pyrolysis front in TLUDs

[Paul S. Anderson]

Crispin and all,

Quoting Crispin Pemberton-Pigott <crispinpigott at gmail.com>:
> So there are some theoretical reasons justifying the claim that a TLUD might
> well have a very linear burn rate even as the fuel is consumed in a
> relatively tall container.  This should also convince you to try building
> taller stoves with higher internal chimneys and deeper fuel loads.  Perhaps
> you can get to a 75 minute 'cook' on a single load (a time I feel essential
> to achieve for it to become popular).

Your observations are correct except there is no need to make the internal
chimney any taller.  (And if the TLUD has forced air, there is no internal
chimney at all, so the stove can remain at a reasonable height.)

That is what was done in Cambodia last December.  With forced air 
support, there
was a TLUD with about 60 cm height for fuel.  Worked well and with a long burn
time, BUT the fuel canister becomes a little heavy (and remember that it is
very hot) to lift out to empty and/or to continue the cooking with a second
canister.  We made large tongs (like tongs for picking up meat on an 
BBQ grill)
specific to help pick up the canister, but it was still not sufficiently user
friendly.

My current efforts include having a "char release out the bottom" 
solution. This is what Alexis Belonio has in his 2005 Rice Husk 
gasifier.  But his is
more complex than I want mine to be.  I have about 4 variations that I hope to
try soon.

The objective is a taller TLUD that is stationary.  That is, it could be built
into a permanent location of metal or mud or brick.  It is loaded from the top
and is top-lit.  But after the pyrolysis is ended, the char/ash can be removed
by opening the bottom.  I have work to do on this.

Of course, quality fuels like hardwood chips and pellets can give extended
burn-times already.  But we do need to accomplish longer burns with lesser
fuels.

Please note:  At ETHOS Simon Anderson and I showed a Chip Energy Biomass Grill
that operates continually.  If long burn times are so important for a society
or industry, that unit would be appropriate.  (For those who have not seen it,
please go to
www.chipenergy.com .)  The basic version (on the red cart at ETHOS and in the
photos) is already for sale at $150 in the USA, with options available.  For
production and use in developing countries, the production cost would 
certainly
be less.  Chip Energy (my company with partner Paul Wever) is not 
positioned to
finance a pilot project.  But if funding for a pilot project with this
continuous feed gasifier becomes available, I am ready to
conduct/help-others-conduct the project in almost any location (combate zones
are excluded).

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson




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