[Stoves] Charcoal Rocket Stove, Charingina"low-cost retort kiln"ICPS

[adkarve]

Dear Kevin,
we sprinkle a little water on the char with the help of a watering can to
quench it. In any case, we have to add starch paste as a binder to it. So it
soes not matter if it is wetted. It does not rot, if stored wet. Refer to
Terra Preta.
Yours
A.D.Karve
----- Original Message -----
From: Kevin Chisholm <kchisholm at ca.inter.net>
To: Discussion of biomass cooking stoves <stoves at listserv.repp.org>
Sent: Monday, June 11, 2007 7:30 PM
Subject: Re: [Stoves] Charcoal Rocket Stove,Charing ina"low-cost retort
kiln"ICPS


> Dear AD
>
> I haven't done this myself, but as I understand from others, a drum of
> ignited charcoal will "breathe."
>
> Basically, as it starts to cool, it draws in air that burns more
> charcoal. The drum heats up, and the inflow of air stops. The drum then
> starts to cool, and then draws in more air...
>
> Is there perhaps a secondary mechanism that is working for you?
>
> Specifically, is it possible that with the relatively small volume of
> char in your drums, the heat loss happens rapidly enough such that the
> char is cooled below its ignition point faster than it can be re-ignited
> by in-leaking air?
>
> Can you visualize any other mechanism that may be at play, to quench the
> charcoal and avoid "breathing loss?"
>
> Best wishes,
>
> Kevin
>
> adkarve wrote:
> > Dear Crispin,
> > since the biomass to be charred is enclosed in a drum, it does not get
any
> > oxygen. So any heat applied to the drum, from the outside, would not
burn
> > the char already formed inside the drum. In case a small part of it were
> > actually to burn, the CO2 would drive the oxygen out and eextinguish the
> > fire.
> > Yours
> > A.D.Karve
> > ----- Original Message -----
> > From: Crispin Pemberton-Pigott <crispinpigott at gmail.com>
> > To: Discussion of biomass cooking stoves <stoves at listserv.repp.org>
> > Sent: Monday, June 11, 2007 12:25 PM
> > Subject: Re: [Stoves] Charcoal Rocket Stove,Charing in a "low-cost
retort
> > kiln"ICPS
> >
> >
> >> Dear Chris and Jim
> >>
> >> First, that is a good idea, Jim.  And it provokes a question for Chris:
> >>
> >> If I have an upside down Karve-drum with biomass in it and a hole in
the
> >> bottom, and I roast it in an enclosure until the gases start to come
out
> >> which feed the fire, and the fire burns with those gases only, does it
> > come
> >> to a stop by itself?  What if I keep supplying air to the system using,
> > say,
> >> a chimney drafting air through a system which is now nice and hot?
Will
> > it
> >> continue to burn at least some of the charcoal?
> >>
> >> I was looking at Jim's suggestion and thinking of the Hoffman kiln
where
> >> there are perhaps 24 rooms linked in a chain.
> >>
> >> Stage One
> >> The charcoal could be made in one room and then if the fire was self
> >> extinguishing, it would go out by itself.  The hot combustion products
> > would
> >> be directed into the adjacent room two.  The next room would have to be
> >> ignited on command at a certain time.
> >>
> >> Stage Two
> >> The second room, in a Hoffman kiln, receives air preheated by passing
> >> through the first room.  This cools the first room and raises the
thermal
> >> efficiency of room two.  If the charcoal in the closed , but perforated
> >> drums in room one does not continue to burn, the Hoffman principle will
be
> >> useable.
> >>
> >> Stage Three
> >> The idea is that in room three, the exit gases from room two are
> > preheating
> >> the load even as the retained heat from room one preheats the air.
When
> >> room three is burning, both rooms one and two provide preheating.
> >> Meanwhile, the heat left over after pre-heating room three passes to
room
> >> four and so on to the exhaust point.  In full swing, there are several
> >> cooling rooms giving up heat to the air going to the room-on-fire, and
> >> several getting preheated by the combustion products.  There are lots
of
> >> gates that control the air so the process can move in a circle
> > continuously.
> >> This is how bricks are often made.  Such a process is extremely
efficient.
> >> I measured 550 degrees preheating at CIMOC's brick factory in Boane
> > outside
> >> Maputo (just to put a number on it).
> >>
> >> With charcoal making, there is enough heat available in the biomass
> >> volatiles that there may be no need to light a fire more than once in
the
> >> beginning.
> >>
> >> I foresee two problems: the drums will vanish in the hot, oxygen-rich
air
> >> after a few 'rounds' and there might be a massive, unexpected
production
> > of
> >> unburned combustible gas somewhere in the middle of the system after it
> > gets
> >> going.
> >>
> >> Maybe it is safest to do it in a single 'charge' of perhaps 10 or 20
pairs
> >> of drums.  maybe even a single line.  Chris: how about a snake of mud
> > brick
> >> walls that allows one drum after another to be set alight in a chain?
The
> >> drums are put into a grid pattern but the fire proceeds in a snake-like
> >> fashion through them?
> >>
> >> Regards
> >> Crispin
> >>
> >>
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