[Stoves] Misuderstanding of TLUD stoves Re: Refuelable TLUD Coal Stove developed in Mongolia that is not a batch process.
Paul S. Anderson
psanders at ilstu.edu
Thu Mar 3 13:30:56 CST 2011
Quoting Crispin Pemberton-Pigott <crispinpigott at gmail.com>:
snipped
>
> A TLUD is just a down draft built upside down. They can be refuelled
> continuously but if the desire is to get char out, that could be a
> problem.
>
This is a very common misunderstanding that was even promoted by Tom
Reed who initialy call it "inverted down draft" gasification.
In a true downdraft gasifier, there is a hot zone that stays at the
bottom all the time, and the fuel moves downward to it, becomes char
and is later subjected to char gasification. The air flow is also
downward.
In a TLUD, the hot zone starts at the top, but then the hot pyrolysis
front migrates downward until reaching the bottom of the fuel pile.
That is FUNDAMENTALLY DIFFERENT from the downdraft gasifiers.
Furthermore, after the pyrolysis front reaches the bottom, the air
flow still continues to be updraft. Placing a significant amount of
fuel onto the top of the fuel bed can cause variations in the gases
created (initially much water vapor while the fuel is drying, then the
pyrolytic gases start later).
Note: In the case of the Chip Energy Biomass Furnace
(www.chipenergy.com) which is a true updraft gasifier with continuous
operation (and the hot zone is at the bottom where the air is
entering), the new fuel enters in small amounts, avoiding the problem
mentioned in the above paragraph about water vapor.
I hope this helps explain what is happening in the TLUDs
Paul
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