[Stoves] Inverted top lit updraught

Sat Jan 14 21:50:48 CST 2012

Das ( cc List) 

Thanks for the added information, which I am forwarding also to "stoves". 

I look forward to your video. 

This is somewhat like the message sent in today by Alex English, which I will forward to you. Both are BLDD, but neither (yet) appropriate (I think) for cooking - and not yet for charcoal-making. 

Ron 
----- Original Message -----
From: "Agua Das" <aguadas at onebox.com> 
To: rongretlarson at comcast.net 
Sent: Saturday, January 14, 2012 12:43:29 AM 
Subject: Re: [Stoves] Inverted top lit updraught 

The ejector conveys the gas and secondary air to the forge. This 
allows access to the molten metal without the need for a flue. 
I can heat bronze to 2150 F in 20 to 40 minutes ( as fast as propane). 
Using 1 to 3 lb wood per pound of metal melted. This is a major 
improvement over traditional village metalworking such as charcoal 
melting which uses 5 lb charcoal per lb metal melted. If it takes 5 
lb wood fuel to make a lb charcoal, then the overall forest 
requirement is 25 lb wood per lb melt. 

I will soon post Utube of a wood chip fueled bronze pour. 

What a fine forum of great minds comes together for Ethos. 

Das 

On 1/12/12, rongretlarson at comcast.net <rongretlarson at comcast.net> wrote: 
> Tom (cc Andrew and list): 
> 
> Thanks. Professor Prasad is certainly one of my heroes in stove work. It was 
> fun to read (I need to re-read) this report on a helpful down draft design. 
> But char production was not a part of his analysis. I will look more closely 
> to see if there is something there to allow for a char-making design. I 
> think the main issue is predicting something on needed chimney heights - 
> which seems to be in there. But it appears to me that both primary and 
> secondary air were traveling through the fuel - whereas I presume a need to 
> separate the air supplies - as in the TLUD. 
> 
> The message (below) by Andrew to the stoves list was at least in part 
> generated by some off-list conversation that we have been having on BLDD and 
> char-making. The issue is why are almost all gasifiers (which can be 
> operated to give sizeable char output) based on BLDD, but (apparently) all 
> (?) char-making stoves are TLUD? 
> 
> I hope anyone knowing of a BLDD char-maker will let us know. 
> 
> Few items below also on Andrew's e-mail.. 
> 
> 
> ----- Original Message ----- 
> From: "Tom Miles" <tmiles at trmiles.com> 
> To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org> 
> Sent: Thursday, January 12, 2012 5:23:21 PM 
> Subject: Re: [Stoves] Inverted top lit updraught 
> 
> Krishna Prasad described the downdraft stove in a presentation to ETHOS in 
> 2004 
> http://www.vrac.iastate.edu/ethos/ethos05/proceedings2004/presentations/pras 
> adbiomasscookstoves.pdf 
> 
> 
> A picture and WBT for Peter Verhaart's down draft barbeque can be found at: 
> http://www.stoves.bioenergylists.org/verhaartbarbeque 
> 
> Tom Miles 
> 
> -----Original Message----- 
> From: stoves-bounces at lists.bioenergylists.org 
> [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of 
> ajheggie at gmail.com 
> Sent: Thursday, January 12, 2012 2:48 PM 
> To: Discussion of biomass cooking stoves 
> Subject: [Stoves] Inverted top lit updraught 
> 
> One for Peter Verhaart to comment on perhaps: we probably all know by now 
> the genesis of the inverted down draught stoves which Ronal and Tom Reed 
> expounded early on this list and concurrently Paal was developing with his 
> early Peko Pe and we understand how burning the pyrolysis offgas can offer 
> very low particulates compared with burning whole wood in a conventional 
> updraught stove but is the same true of a down draught stove if the primary 
> air is similarly controlled? 
> [RWL: I think Piet Verhaart's thoughts would be excellent (for others: 
> Piet's doctoral work was on a BLDD stove). But for this purpose, I am 
> interested right now in whether any BLDD is providing (lots of) char. 
> 
> The advantage of stratified down draught ( i.e. where the air moves down 
> through the charge of wood as that also descends through the grate) would 
> seem to be that the fire can be continually stoked. The disadvantage is all 
> the extra pipe work and either needing a hot plate or sunken pots to 
> maintain the chimney depression required to suck the primary air down. 
> [RWL: I think Professor Prasad's paper shows a BLDD design that doesn't 
> suffer from these two drawbacks. But also it doesn't seem to produce char. 
> 
> Down draught devices are normally intended to gasify all the fuel, often 
> with extra air supplied in the "throat" but what if one was not particularly 
> concerned if a high char ash were left? 
> [RWL: I have recently been talking with Agua Das [cc'd] about his "Dasifier" 
> - which is incredibly efficient (very high temperatures) with an "ejector" 
> supplying this extra air . He says he can produce lots of char as well. This 
> is not what I have had in mind - but could be attractive if that 
> intermediate secondary air can be introduced and controlled economically. 
> 
> For the sake of staying on topic can we avoid the "b" word and just discuss 
> the concept? 
> [RWL: Hmm. "b" word ? I trust it is OK to talk of saved char (intended for a 
> "b" purpose). 
> 
> Andrew - thanks for these thoughts. 
> 
> Ron 
> 
> AJH 
> 
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