[Stoves] is this new?

[Marc Pare]

That cutaway is beautiful! Great example of "let the product speak for
itself"

Since seeing counterflow in action, I understand exactly what you're
describing with the air flows.

I didn't understand your emphasis on keeping the flame near the bed with a
"descending burner" until this paragraph:

The secondary air is send across the surface to keep a deck of flame going
at the height of the holes. This obviates the need for adding a circular
disk at the top to ’keep the flame going’. Adding a ‘concentrator’ as Paul
calls it takes more material and moves the fire too far away from the heat
of the pyrolysis bed leading to unwanted flame-outs from time to time.


I've seen these instabilities quite often in small-scale pyrolyzers. Great
to see a practical measure to prevent their tendency to "smoke bomb".

What's on the "to-do" list for this class of design, Crispin? Are you
looking to push it into other applications? Apply the principles to improve
existing design? (like you mentioned with advancing the Anglo SupraNova)

Marc Paré
B.S. Mechanical Engineering
Georgia Institute of Technology | Université de Technologie de Compiègne

my cv, etc. | http://notwandering.com


On Mon, Jan 21, 2013 at 9:42 AM, Crispin Pemberton-Pigott <
crispinpigott at gmail.com> wrote:

> Dear Marc and Ron and All interested in air flows****
>
> ** **
>
> This is a response to questions about air and Marc’s tube.****
>
> ** **
>
> Here is an old photo of secondary air entering the combustion chamber of a
> Vesto pushing the flame to the centre. This accomplishes the following:***
> *
>
> ** **
>
> Keeps the fire away from the wall, reducing the temperature it has to
> survive (a lot)****
>
> Keeps the flame going****
>
> Not allowing it to spread to one side away from the smoke on the other
> side that might otherwise ‘get away’.****
>
> Provides turbulent mixing of flame, hot secondary air and smoke****
>
> Allows for preheating to a significant degree (250-500 C)****
>
> ** **
>
> [image: cid:image001.jpg at 01CDF756.FE0F8310]****
>
> ** **
>
> Here is an example (hard to see of course because it is a still taken from
> a video) of the spinning of the flame caused by the shaped grate at the
> bottom.****
>
> ** **
>
> [image: cid:image006.jpg at 01CDF756.FE0F8310]****
>
> ** **
>
> The fire is circular because it is spinning rapidly, though pushed to the
> side by the way the fuel happened to be sitting. The spin adds turbulence
> without a fan and assists in keeping the flame away from the combustion
> chamber wall.****
>
> ** **
>
> Here is a Vesto burning switchgrass pellets operating as TLUD, showing
> that there is nothing special about a TLUD in the sense of it having to
> operate in a particular fashion. The air flow through the fuel is reduced
> by the fuel and it operates as a TLUD. The secondary air is send across the
> surface to keep a deck of flame going at the height of the holes. This
> obviates the need for adding a circular disk at the top to ’keep the flame
> going’. Adding a ‘concentrator’ as Paul calls it takes more material and
> moves the fire too far away from the heat of the pyrolysis bed leading to
> unwanted flame-outs from time to time. A major issue with all pyrolysing
> TLUD’s. It is simply not necessary. Just keep the fire near the fuel. This
> also provides additional vertical space for the flame to finish burning
> before getting to a cold pot surface.****
>
> ** **
>
> Here is a really cool picture of a Vesto burning walnut shells in TLUD
> mode.****
>
> ** **
>
> [image: cid:image009.jpg at 01CDF756.FE0F8310]****
>
> ** **
>
> Finally, here is a photo of a Vesto cutaway showing the inside parts in
> their correct positons.****
>
> ** **
>
> [image: cid:image010.jpg at 01CDF756.FE0F8310]****
>
> ** **
>
> The primary air controller is the ring with holes in it. When the handle
> is moved to the side the holes are closed.****
>
> ** **
>
> Regards****
>
> Crispin****
>
> ** **
>
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