[Stoves] TLUD advances -- Two more uses of char

[Stephen Joseph]

All

Japanese quench biochar with ash.  This also helps to functionalise the
surface of the biochar and make it more active

I actually use a mixture of soil and ash as the heat can help release
locked up phosphorous.

Regards
Stephen Joseph

On Mon, Apr 29, 2013 at 2:01 AM, Paul Anderson <psanders at ilstu.edu> wrote:

> Dear all,
>
> These two and many other "tips" need to be collected and told to TLUD
> stove users.   One avenue is in Christa's Manual,   Another is in stove
> manuals and at training sessions.   And at websites, etc.
>
> 1.  Charcoal to extinguish hot charcoal:   When dealing with small amounts
> of hot charcoal as in the residential TLUD stoves, one easy way to
> extinguish hot charcoal is to dump it into a somewhat larger amount of
> already extinguished (cold) char.   The cold char takes up much of the
> heat, extinguishing the hot char.   Be sure that it is well mixed and
> sufficiently cooled to avoid re-ignition.  This is best done in containers
> that can be sealed.   Containers of metal or ceramic are best, but even
> wood could be used if the quantity of cold char is sufficient to prevent
> the hot char from reaching the sides.   As always, be careful because
> oxygen to a small hot ember can lead to much greater combustion.
>
> 2.  "Space fillers" in loose fuels in TLUD devices:
>
> General note about fuel in TLUDs:
> In general, dry biomass fuels in TLUDs need to appropriately fill most of
> the air-space in the fuel chamber.   This is accomplished with smallish
> pieces such as wood chips, pellets, short-cut twigs, and shells of seeds.
> Also, careful packing with vertical wood-segments or straight-ish reeds can
> occupy the space.   But twisted sticks and long-ish pieces that bridge
> inside the fuel chamber leave too much space unoccupied.   In those cases,
> the space can be appropriately occupied by adding small pieces, as named
> above.   Shake the TLUD to assure that the pieces have settled in well, and
> add more as needed.   These fillers will also pyrolyze and become charcoal.
>
> Inert materials as "space fillers":   Technically, the space fillers could
> be inert materials such as ball bearings or pebbles (of rock that will not
> shatter with this heat) or fired clay balls.  Although they could function
> effectively, they would require separation after the batch is unloaded and
> cooled.   But there is one material that solves these inconveniences and
> costs.  It is charcoal.
>
> Charcoal as a space filler:   TLUD stoves make charcoal. Therefore,
> charcoal is not a fuel for TLUD stoves.   However, small pieces of charcoal
> (but not charcoal fines) can also be used as "space fillers" to solve the
> need to restrict air flow in the fuel chamber.   The char will not pyrolyze
> and will not burn (char-gasify or oxidize) as the pyrolysis front moves
> downward through that biomass fuel.
>
> a.  Char is abundant for TLUD users, and at no additional cost, and is not
> consumed.
>
> b.  Unlike small pieces of biomass as fillers, char pieces cannot catch on
> fire and then fall down to the lower areas of the fuel chamber and igniting
> fire there.
>
> Charcoal as a reducer of thermal output:   Clearly in the above statements
> when charcoal is used as a space filler, the fuel chamber contains less
> biomass and therefore less heat will  be generated (which is desirable for
> simmering and some other cooking needs).
>
> Another variation is to have well packed (mainly straight) wood or reeds
> or stems as a vertical bundle in the middle of a TLUD fuel chamber.  Then
> load in small charcoal all around the bundle to fill in the remaining
> space.   When used (pyrolyzed), the fuel will yield heat in proportion to
> its cross-sectional area of the fuel bundle, not of the entire
> cross-sectional area of the fuel cylinder.  This is because the annulus of
> char is essentially non-combustible at the pyrolytic temperatures in the
> TLUD reactor.
>
> Variations of all of the above need to be tested and even measured.
> (This will be utilized at the Stove Camp at Aprovecho 22 - 26 July 2013).
>
> Note:  Credit for much of the above goes to Dr. Jack Bacon, a senior
> scientist at the NASA Johnson Space Center in Houston, TX.   Jack, a leader
> in the local chapter of Engineers Without Borders (EWB-JSC), suggested
> charcoal as fillers during discussions in April 2013 with Paul Anderson
> about an EWB project to use TLUDs for heat in a fruit dryer in Rwanda.
>
> Dr TLUD
>
> --
> Paul S. Anderson, PhD  aka "Dr TLUD"
> Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
> Website:  www.drtlud.com
>
>
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