[Stoves] Top lit updraft combustors

[Norbert Senf]

On Wed, Dec 13, 2017 at 7:57 PM, Ronal W. Larson <rongretlarson at comcast.net>
wrote:

> Norbert and list:*(snip)*
>
>
> As an outsider to the TLUD scene, I'd note that we make a top lighting
> updraft combustor,
> in the form of a heating appliance indigenous to northern Europe. The top
> lighting is
> not mandatory or traditional, but has been found through testing to be a
> preferred mode
> of operation for combusting a batch load of cordwood in the 10 - 40 kg
> range with very low
> particulate (PM) emissions.
>
> *[RWL:  Can you give a lead to look this up?   Makes char?  Probably not
> as you say “combustor”*.  Any theory on why top lighting is cleaner?  Do
> you always operate batch load only?
>

>>>Ronal: It is a combustor. It is similar to a masonry fireplace, except
burns a 60 lb batch and stores the heat. Two 50 lb fires per day gives you
6 kW continuous for house heating. Because of thermal storage, you can use
an optimized single burn rate which makes it easy to burn clean. The trick
is the cold start, and getting the firebox up to temperature so you have
your 3T's. Top ignition gives you a small hot fire right away, whereas
bottom ignition results in quenching of the flames by the cold fuel pile
above.
http://heatkit.com/

>
> A newly developed combustion air system from Austria can be configured to
> produce biochar as a byproduct. I fooled around with this last winter, and
> was able to
> make around 300 kg, as a byproduct of heating our house. We have conducted
> EPA-style
> dilution tunnel PM testing on this as well as on pellet (heating) stoves,
> and are burning cordwood with
> about half the PM emissions of pellet stoves.
>
> *[RWL:  Can you give us a lead on the Austrian group?*
>

Here is the specification, from the Austrian tile stove association:
mha-net.org/docs/codes/austria/MB_10_eco-friendly%20combustion%20chamber_20120424Version2.pdf
Here is some info on the testing that we have done on it:
http://www.heatkit.com/research/lopez-2014-03-01.html

* Can you say a bit more about your own 300 kg of char-making?  I pull char
> (with tongs) regularly (when I think of it) out of my very small wood
> stove.  What sort of char-making efficiency in your method?  (I have no
> idea on mine, but it is not hard to do - and is my concept on how char was
> produced for the Terra Preta soils.)*
>

A rough guess is 5% - 10% of the (wet) weight of the 20% moisture cordwood.
When the yellow flaming has stopped on the batch and there is a big coal
bed, I shut off the air. The next morning, I scoop out the ash + coals,
some of which are still live, into a metal ashbucket with a tight lid. I
keep the ash + char mix in bags until the spring, when I screen it all to
separate the charcoal.

>
> You can find some details here:
> http://heatkit.com/research/2006/lopezm02.htm
>
> *[RWL:  I thought you did a nice job in explaining your whole lab
> process.  I tried to learn more about Condar - but no web site was found.
> Is this a method or a product?*
>

It used to be an official method in Oregon, OM41. It was a commercially
produced product in the 1980's, and used to develop all of the first
generation of clean burning EPA-certified stoves. We have an original, and
have had copies made. Here is a transcript of a workshop that was prepared
for us by OMNI Environmental, one of the top EPA-accredited labs:
heatkit.com/docs/OMNIcourse.pdf

It features the late Dr. Stockton (Skip) Barnett, the inventor of the
Condar.

We have a repository of some technical documents here:
http://heatkit.com/html/lop-arc.htm#Condar_Sampler


> * I stumbled on the stove decathlon.  Any comments for us on whether that
> could help our interests with much smaller stoves?*
>

I don't know. John Ackerly of Alliance For Green Heating has attended some
of the cookstove conferences
http://forgreenheat.blogspot.ca/2014/02/experts-gather-in-northwest-to-design.html

There seems to be a real divide between the EPA heating stove certification
scene in the US, and the international cookstove/biochar scene.
Any connections that can be formed to harmonize test methods, or even
emissions definitions, would be beneficial to everybody.

> Norbert
>
>
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