[Stoves] World stove, fantasy draft, flame caps, TLOD, TFOD, DS

Ronal W. Larson rongretlarson at comcast.net
Sun Apr 1 23:55:05 MDT 2018

Kelpie and list;  Adding Nat Mulcahy

	1.  Re your last sentence, my reading on Venturis	says that big pressure differences can be generated.  The word “vacuum” means something here.

	2.  This may be really off-the-wall, but I can (vaguely) see adapting the “TLOD” actions of World Stove to really large Kon-Tiki type systems.  Couldn’t be exactly like Nat’s but I can imagine a double walled “Kon-Tiki” with a floor that has “holey” pipes, with a fan/blower system (might want more than one) a ways off that draws hot gases out of these “holey floor pipes” and then re-injects the hot gases now mixed with air back into the double wall kon tiki- to give controllable flames  

	3.   Advantages (possibly):
	a.  The kon tiki could be preloaded - perhaps right to the top (as is the Lucia and others)
	b.  There could be an optimum amount of added air - for premixing, but still able to form an oxygen - rejecting flame cap.
	c.   The hot N2 drawn down would create char.
	d.   There would never be glowing embers.  The fire would self extinguish when all the wood has been converted to char.(I think this is the biggest possible advantage)
	e.  You could add extra wood if desired at any time.
	f.  The duration and size of the flame could be controlled by the fan(s) speed(s).
	g.  The energy for the fan should be relatively small, and there are technologies to generate the needed fan power from the flame (for remote areas).
	h.  These probably better long and “narrow”
	i.  Could be totally separate fans for the added air,  or a Venturi effect might work here as well.
	j. A way-out possibility is that it could all work natural draft.


> On Apr 1, 2018, at 5:58 PM, Kelpie Wilson <kelpiew at gmail.com> wrote:
> Hi friends,
> sorry but I get the email digest and cannot figure out how to reply to a subject thread, so I'll just start a new one.
> This is so interesting! I just got back from a workshop tour of Nebraska and Kansas, teaching flame cap pyrolysis for making biochar from invasive eastern red cedar. This use of waste biomass for biochar has been my focus in recent years, rather than stoves or TLUDs. 
> So many times, I have seen flames from these kilns flowing upward and then turning back down. The flame tips have a downward hook at the top as something sucks the the air back down. These are Down Suckers, thank you Paul for that term!
> You can see a nice example of this pictured in my slides here: 
> https://www.slideshare.net/kelpiew/flame-carbonizers-for-biochar-in-practice-and-theory <https://www.slideshare.net/kelpiew/flame-carbonizers-for-biochar-in-practice-and-theory>
> Of course these flame cap kilns have no bottom air, but in the beginning stages of a burn, the air does flow down the sides and up the center of the fuel stack so they do operate in an updraft mode of sorts. So some of it is the air flow down the sides that is sucking the air from above and causing the flame tips to hook downward. However, in the later stages of the burn, we have completely filled in the kiln with hot glowing coals and air still comes from the top because the combustion must create a negative pressure to pull air in from the top. Which of these down-sucking affects might be taking place in a small stove?
> I also have to agree with Gordon, and with Bill Knauss, that there must be positive pressure from the wood gas as heat forces the volatiles out of the wood. That would be how the Everything Nice/World Stove works. Heat from the flame on top volatilizes gas down inside the stove. Pressurized gas flows up to the top of the fuel bed, feeding the flame, but some flows out through the side holes, gaining speed as it passes through the venturis, creating more negative pressure to draw more gas. In the annular space it pre-mixes with secondary air for better combustion. This pre-mixed gas then merges with the flame on top.
> It is not all about draft and buoyancy. Gas flows also occur from volatilization and oxidation. 
> So the World Stove is definitely not a down-draft gasifier, but it is more than a TLUD. In fact, I have felt for awhile that a flame cap kiln is more like a retort than anything, since it is closed on the bottom. The flame itself closes the retort and acts as heat exchanger at the same time. 
> The World Stove just acts like a self-heating retort with a flame cap, as pressurized syngas leaves and recirculates to the flame. 
> I agree that I would really like to see someone evaluate Nat's claims about N-enriched char from his stove. That would be proof that down-sucking gas actually moves from the top through the fuel like a sweep gas. Not too sure that could actually happen. The venturi effect would have to be very strong.
> Kelpie
> -- 
> Ms.Kelpie Wilson
> Wilson Biochar Associates <http://www.wilsonbiochar.com/>
> Email: kelpiew at gmail.com <mailto:kelpiew at gmail.com>
> Oregon home office: 541-592-3083
> Mobile: 541-218-9890
> Skype: kelpie.wilson
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