[Stoves] Stoves Digest, Vol 125, Issue 6

Tue Jan 12 18:25:37 CST 2021

Thank you Andrew. Most appreciated

Kevin;

One aspect of biochar kiln function is the presence of water in the air
when we have a high relative humidity. I suspect the smoke was from that
since our RH is about 99% at the moment. I plan to retest in the summer
when RH is low. Still from what I saw with a coarse sawdust, there was a
lot of smoke. With fine sawdust, there is a problem with air transmission
otherwise the char would not have burned at the edges of the can when I did
a burn. I will check for more websites.

Norm

On Tue, Jan 12, 2021 at 2:07 PM <stoves-request at lists.bioenergylists.org>
wrote:

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>    1. sawdust stove (ajheggie at gmail.com)
>    2. Re: sawdust stove (K McLean)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 12 Jan 2021 18:42:52 +0000
> From: ajheggie at gmail.com
> To: Discussion of biomass cooking stoves
>         <stoves at lists.bioenergylists.org>
> Subject: [Stoves] sawdust stove
> Message-ID:
>         <CAPSaZebZ=
> 2wEbqsr4eoVsYZEfVoTJo76zhARgdyvyZg_a80LPg at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> A message from Norm Baker which was too big for the list so I resized
> the pictures
>
> Andrew
>
> Gentlemen;
>
> Out of simple curiosity I built a sawdust stove. In nearly 15 years of
> messing with TLUDs I had never heard of a sawdust stove, so I followed
> the original publication and constructed one from a 7 gallon popcorn
> can. Took about 15 minutes for construction. Here is what I found of
> interest;
> a. First, I dried the red Alder sawdust from a local lumber mill over
> electric heat and I know the moisture content was less than 10%.
> b. It is a touchy stove. Even when I firmly packed the dry sawdust,
> the sawdust was very susceptible to collapsing inward on the central
> hole when the pipe was removed.
> c. It smoked for the entire burn.
> d. Interestingly, the smoke had the turbulence seen in a flame cap
> kiln and rolled over the edge of the popcorn can and into the flame. I
> could tell much of the smoke was consumed but not nearly enough.
> e. As the sawdust was consumed, after flames cover the entire
> horizontal surface of the sawdust, the char started combusting and the
> translucent blue flames were easily visible around the edge of the
> stove.
> f. Touching the stove in any fashion, resulted in a surprising amount
> of sparks in the exhaust stream. These sparks or fireflies went as
> high as 10 foot up into the air before being extinguished in the air
> or on wet vegetation nearby.
> g. I was surprised that the stove had a 2 1/2 hour burn time on four
> kilograms of sawdust.
>
> All in all, an interesting stove, but not one I would recommend anyone
> start using. The amount of smoke and hot sparks are simply
> unacceptable.
>
> Norm
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> ------------------------------
>
> Message: 2
> Date: Tue, 12 Jan 2021 15:00:58 -0500
> From: K McLean <kmclean56 at gmail.com>
> To: Andrew Heggie <ajheggie at gmail.com>,  Discussion of biomass cooking
>         stoves <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] sawdust stove
> Message-ID:
>         <
> CALxcr-ty1HFi_fFmLQR4A_rGo5EcD+RZr2pdRA1H9THZ6a_oKw at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Norm,
>
> I am very excited about sawdust stoves. I have colleagues in Uganda, Kenya
> and Malawi testing them.  Their testing is crude but uniformly successful.
> In fact, the wife of one of them has completely stopped using charcoal and
> is now only cooking with sawdust.  He says the stove burns for five hours
> without tending.  There is smoke when starting but almost no smoke
> thereafter, similar to charcoal. Their stove is 27 cm high and 26 cm
> diameter
>
> He also tested a stove 25 cm high and 21 cm diameter which works well.  It
> cooked for just over 2 hours.
>
> There are many websites that discuss making sawdust stoves out of used
> gallon paint cans.  Metal paint cans are getting hard to find now in Africa
> and Asia, though.  I tested sawdust in a gallon paint can with mixed
> results.  I sourced my sawdust from a cabinet maker.  The sawdust is very
> fine, like dust.  That may be my problem.  After packing the sawdust and
> removing the pipe, the center hole held.  But the sawdust would not burn
> without an external flame from below.  When the external flame was removed,
> the sawdust smoldered until all of the sawdust turned to char.  The amount
> of smoke was unacceptable.
>
> [image: image.png]
>
> This sawdust stove is built like a traditional rocket stove, with a hole on
> the side.  Some of my colleagues prefer this design over stoves with the
> hole in the bottom.  If the hole is on the bottom, the stove must be
> elevated (eg, with bricks).
>
> They have tested with many fuels and continue to test with more fuels and
> fuel mixtures.  These fuels work, though none work as well as sawdust:
> maize cobs, maize stalks, rice hulls, rice straw, banana peels, cassava
> peels.  Some fuels like rice hulls cannot sustain a flame by themselves.
> They need firewood or other fuel burning.  A single maize stalk burning
> below the rice hulls does the trick.  Pine needles haven't worked in our
> testing.
>
> The stoves tend to emit very little smoke and they produce biochar.
>
> A concentrator ring on top helps.
>
> We are working on designs that will be affordable to even the poorest
> families, $1-2.
>
> I see great potential with sawdust stoves for shifting cooking fuel from
> nonrenewable wood to renewable sawdust and crop waste.  My colleagues say
> that where they live huge piles of sawdust can be found at sawmills and
> even at carpenter shops.  There is no use for the sawdust so it is often
> just burned.  I've heard the same about piles of rice hulls.
>
> Sawdust stoves had been around for decades.  I don't know why they are not
> ubiquitous.  I'm sure others on this list have experience with sawdust
> stoves and can explain what is a conundrum to me.
>
> Kevin McLean
> Sun24
>
> On Tue, Jan 12, 2021 at 1:46 PM <ajheggie at gmail.com> wrote:
>
> > A message from Norm Baker which was too big for the list so I resized
> > the pictures
> >
> > Andrew
> >
> > Gentlemen;
> >
> > Out of simple curiosity I built a sawdust stove. In nearly 15 years of
> > messing with TLUDs I had never heard of a sawdust stove, so I followed
> > the original publication and constructed one from a 7 gallon popcorn
> > can. Took about 15 minutes for construction. Here is what I found of
> > interest;
> > a. First, I dried the red Alder sawdust from a local lumber mill over
> > electric heat and I know the moisture content was less than 10%.
> > b. It is a touchy stove. Even when I firmly packed the dry sawdust,
> > the sawdust was very susceptible to collapsing inward on the central
> > hole when the pipe was removed.
> > c. It smoked for the entire burn.
> > d. Interestingly, the smoke had the turbulence seen in a flame cap
> > kiln and rolled over the edge of the popcorn can and into the flame. I
> > could tell much of the smoke was consumed but not nearly enough.
> > e. As the sawdust was consumed, after flames cover the entire
> > horizontal surface of the sawdust, the char started combusting and the
> > translucent blue flames were easily visible around the edge of the
> > stove.
> > f. Touching the stove in any fashion, resulted in a surprising amount
> > of sparks in the exhaust stream. These sparks or fireflies went as
> > high as 10 foot up into the air before being extinguished in the air
> > or on wet vegetation nearby.
> > g. I was surprised that the stove had a 2 1/2 hour burn time on four
> > kilograms of sawdust.
> >
> > All in all, an interesting stove, but not one I would recommend anyone
> > start using. The amount of smoke and hot sparks are simply
> > unacceptable.
> >
> > Norm
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> End of Stoves Digest, Vol 125, Issue 6
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