[Stoves] Dung Berry Fireballs

[lannych]

I have noticed that the 'pilot flame' keeps the 'top gas' burning longer 
with hard to burn fuel that is too moist or has the wrong fuel geometry .

----- Original Message ----- 
From: "Kobus" <ventfory at iafrica.com>
To: <STOVES at LISTSERV.REPP.ORG>
Sent: Monday, November 06, 2006 11:51 PM
Subject: Re: [Stoves] Dung Berry Fireballs


Richard/Lanny,

Saw this a bit late but anyhow... yes in our experiments we found that a
'pilot flame' was very important in maintaining a top-down burn of two
stacked briquettes.  The stack effect produced a yellow flame licking out
the top and igniting unburnt gases formed during the slow top-down flaming
pyrolysis burn on the outside of the stack, ultimately resulting in a
charred briquette stack which would then slowly start to 'burn'  (±25 min
into burn) to ash ±45 min later.  The internal 'pilot flame' required hot
secondary air upon reaching the mid-point of the top briquette and this was
supplied via holes cast into the base of the briquettes.  If the creep rate
of the internal flame is not arrested (primary air), it soon reaches the
base of the stack and eventually creeps around on to the outer rim of the
bottom briquette, as Richard rightly said.

Regards

Kobus




Lanny,

Interesting: This is much like what Kobus and I experienced in

attempting to top lite the hollow core briquette in our briquette

gassifying experiements in south africa. Problem was that the hole was

too inviting and it would end up being a toplit, bottom-burned briquette..

You are right about the need for a central air feed though. Something

is needed to supply air up through the center at least when you are

trying to gassify biomass to our experience. anyway..... (Kobus, your

comments to refine mine most welcome)

Richard Stanley

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