[Stoves] flames touching pot

[Alex English]

Hi Ron,
I have never run TLUDs with an accurate rate of burn measurement like 
mass change over time. In this example the primary air was closed close 
to the limit which allows the increase in excess air added above. This 
puts the flame close/closer to its flammability limits. Yes you could 
say it was on the verge of going out, but didn't.

The double chimney, or at least the lower 2 inch portion is included to 
overcome the choke of reducing to 2 inches. It was useful experimentally 
  but not practically.

I have seen essentially zero CO (CO/CO2 of .0002) during stable flaming 
which excludes start up, shutdown and margins of error associated with 
the equipment.

If I recall CO/CO2 during blue flaming was closer to .01

This difference isn't significant for the stove community. I simply 
found it interesting that burning all these long chain pyrolysis vapours 
could be blue and that premixing was a possibility  using natural draft. 
Anyhow, using wood pellets is cheating isn't it:)

If I remember correctly, 15 years ago Skip Hayden at CANMET's combustion 
lab told this list that a blue flame oil burner had been developed but 
it had been rejected for some reasons associated with its lack of 
radiant heat exchange within the flame.

Alex



On 9/14/2011 5:39 AM, rongretlarson at comcast.net wrote:
> Alex:
>
> Your video showed a flame that I thought might be on the verge of going
> out.
>
> Can you give a turn-down ratio?
>
> Are you quite happy with this "double chimney" (which seems to add a lot
> of height)?
>
> What is the CO ratio in this video - and how good have you achieved?
>
> Ron
>
>
> ------------------------------------------------------------------------
>
> *差出人: *"Alex English" <english at kingston.net>
> *To: *"Discussion of biomass cooking stoves"
> <stoves at lists.bioenergylists.org>
> *送信済み: *2011年9月14日, 水曜日 午前 11:59:40
> *件名: *Re: [Stoves] flames touching pot
>
>
>
>
>  >> The question is why the yellow flame produces soot , but not the blue
>  >> one ?
>
>  > The difficulty with achieving the same with wood gas is that the woodgas
>  > is inherently hot as it meets the air. It would be interesting to cool
>  > the gas from a tlud ( which would mean losing the fuel value of all the
>  > tars present as they would condense) and then using a premixed burner on
>  > the remaining cooled gases.
>
> We've been here before....
>
> The blue ones tend to be well oxygenated (mixed)or even too high in
> "excess air" from an efficiency point of view. I expect there are some
> additional interesting details for ag residues when it comes to
> chemical species and flame colour.
>
> I have been able to get an all blue flame with wood pellets in a TLUD
> using my double chimney set up. It focuses the pryolysis gasses into a 2
> inch diameter chimney and then adds "secondary" air (probably at least
> 100% excess) to premix just before it widens to 4-6 inches and burns,
> blue. They haven't been the lowest CO/CO2 flames I've tested.
>
> Hard to get a good picture, except at night.
>
> http://www.youtube.com/watch?v=rvAwTnezVc8
>
> Alex English
>
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