[Stoves] Flame center go down into the combustion chamber

[Crispin Pemberton-Pigott]

Dear Julien

I have not seen any forced draft stoves from Nurhuda. ‎Are you sure it has a fan? He has specialised in ND so far. All stoves submitted to the CSI project, anyway.

BBM 'Crispin'
From: Julien Winter
Sent: Sunday, March 6, 2016 03:44
To: Discussion of biomass cooking stoves
Reply To: Discussion of biomass cooking stoves
Subject: [Stoves] Flame center go down into the combustion chamber


Dear Roberto et al.;

There are a couple of reasons why you may get secondary air settling down
the middle of the burner.

1)  When there is not enough syngas to create a gas flame across the entire
cross section of the burner, then flame and buoyancy will localize the
updraft.  If the flame originates at the orifices of secondary air, but
can't extend to the center of the burner, then there gases in the middle fo
the burner may settle.

2)  If syngas is entrained into jets of secondary air, then it will be
pulled towards the origins of the secondary air jets.  I saw this happen in
on of my early burners.  There was a torodial ring of 'smoke' under the
secondary air jets.

The radial movement of syngas let me to experiment with burner diameters
and find that a burner that was 1.2 x greater in diameter than the TLUD
reactor worked better than when the diameters were the same.  The wider
burner gave slightly more horizontal space for flame expansion.  The result
was a faster gasification rate (which I presumed, to be because I had a
hotter, more efficient flame).

One final note.  Roberto's burner is natural draft.  Muhammad's burner is
forced draft. We must be careful using observations from forced draft
burners to explain natural draft burners, because they are completely
different animals.  To get the same pressure in a forced draft burning
using natural draft, we would need a riser several meters tall.

Cheers,
Julien.


--
Julien Winter
Cobourg, ON, CANADA
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