<html><head><style type='text/css'>p { margin: 0; }</style></head><body><div style='font-family: Arial; font-size: 12pt; color: #000000'>Das ( cc List)<br><br> Thanks for the added information, which I am forwarding also to "stoves".<br><br> I look forward to your video.<br><br> 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.<br><br>Ron<br><hr id="zwchr"><b>From: </b>"Agua Das" <aguadas@onebox.com><br><b>To: </b>rongretlarson@comcast.net<br><b>Sent: </b>Saturday, January 14, 2012 12:43:29 AM<br><b>Subject: </b>Re: [Stoves] Inverted top lit updraught<br><br>The ejector conveys the gas and secondary air to the forge. This<br>allows access to the molten metal without the need for a flue.<br>I can heat bronze to 2150 F in 20 to 40 minutes ( as fast as propane).<br>Using 1 to 3 lb wood per pound of metal melted. This is a major<br>improvement over traditional village metalworking such as charcoal<br>melting which uses 5 lb charcoal per lb metal melted. If it takes 5<br>lb wood fuel to make a lb charcoal, then the overall forest<br>requirement is 25 lb wood per lb melt.<br><br>I will soon post Utube of a wood chip fueled bronze pour.<br><br>What a fine forum of great minds comes together for Ethos.<br><br>Das<br><br>On 1/12/12, rongretlarson@comcast.net <rongretlarson@comcast.net> wrote:<br>> Tom (cc Andrew and list):<br>><br>> Thanks. Professor Prasad is certainly one of my heroes in stove work. It was<br>> fun to read (I need to re-read) this report on a helpful down draft design.<br>> But char production was not a part of his analysis. I will look more closely<br>> to see if there is something there to allow for a char-making design. I<br>> think the main issue is predicting something on needed chimney heights -<br>> which seems to be in there. But it appears to me that both primary and<br>> secondary air were traveling through the fuel - whereas I presume a need to<br>> separate the air supplies - as in the TLUD.<br>><br>> The message (below) by Andrew to the stoves list was at least in part<br>> generated by some off-list conversation that we have been having on BLDD and<br>> char-making. The issue is why are almost all gasifiers (which can be<br>> operated to give sizeable char output) based on BLDD, but (apparently) all<br>> (?) char-making stoves are TLUD?<br>><br>> I hope anyone knowing of a BLDD char-maker will let us know.<br>><br>> Few items below also on Andrew's e-mail..<br>><br>><br>> ----- Original Message -----<br>> From: "Tom Miles" <tmiles@trmiles.com><br>> To: "Discussion of biomass cooking stoves" <stoves@lists.bioenergylists.org><br>> Sent: Thursday, January 12, 2012 5:23:21 PM<br>> Subject: Re: [Stoves] Inverted top lit updraught<br>><br>> Krishna Prasad described the downdraft stove in a presentation to ETHOS in<br>> 2004<br>> http://www.vrac.iastate.edu/ethos/ethos05/proceedings2004/presentations/pras<br>> adbiomasscookstoves.pdf<br>><br>><br>> A picture and WBT for Peter Verhaart's down draft barbeque can be found at:<br>> http://www.stoves.bioenergylists.org/verhaartbarbeque<br>><br>> Tom Miles<br>><br>> -----Original Message-----<br>> From: stoves-bounces@lists.bioenergylists.org<br>> [mailto:stoves-bounces@lists.bioenergylists.org] On Behalf Of<br>> ajheggie@gmail.com<br>> Sent: Thursday, January 12, 2012 2:48 PM<br>> To: Discussion of biomass cooking stoves<br>> Subject: [Stoves] Inverted top lit updraught<br>><br>> One for Peter Verhaart to comment on perhaps: we probably all know by now<br>> the genesis of the inverted down draught stoves which Ronal and Tom Reed<br>> expounded early on this list and concurrently Paal was developing with his<br>> early Peko Pe and we understand how burning the pyrolysis offgas can offer<br>> very low particulates compared with burning whole wood in a conventional<br>> updraught stove but is the same true of a down draught stove if the primary<br>> air is similarly controlled?<br>> [RWL: I think Piet Verhaart's thoughts would be excellent (for others:<br>> Piet's doctoral work was on a BLDD stove). But for this purpose, I am<br>> interested right now in whether any BLDD is providing (lots of) char.<br>><br>> The advantage of stratified down draught ( i.e. where the air moves down<br>> through the charge of wood as that also descends through the grate) would<br>> seem to be that the fire can be continually stoked. The disadvantage is all<br>> the extra pipe work and either needing a hot plate or sunken pots to<br>> maintain the chimney depression required to suck the primary air down.<br>> [RWL: I think Professor Prasad's paper shows a BLDD design that doesn't<br>> suffer from these two drawbacks. But also it doesn't seem to produce char.<br>><br>> Down draught devices are normally intended to gasify all the fuel, often<br>> with extra air supplied in the "throat" but what if one was not particularly<br>> concerned if a high char ash were left?<br>> [RWL: I have recently been talking with Agua Das [cc'd] about his "Dasifier"<br>> - which is incredibly efficient (very high temperatures) with an "ejector"<br>> supplying this extra air . He says he can produce lots of char as well. This<br>> is not what I have had in mind - but could be attractive if that<br>> intermediate secondary air can be introduced and controlled economically.<br>><br>> For the sake of staying on topic can we avoid the "b" word and just discuss<br>> the concept?<br>> [RWL: Hmm. "b" word ? I trust it is OK to talk of saved char (intended for a<br>> "b" purpose).<br>><br>> Andrew - thanks for these thoughts.<br>><br>> Ron<br>><br>> AJH<br>><br>> _______________________________________________<br>> Stoves mailing list<br>><br>> to Send a Message to the list, use the email address<br>> stoves@lists.bioenergylists.org<br>><br>> to UNSUBSCRIBE or Change your List Settings use the web page<br>> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists<br>> ..org<br>><br>> for more Biomass Cooking Stoves, News and Information see our web site:<br>> http://www.bioenergylists.org/<br>><br>><br>><br>> _______________________________________________<br>> Stoves mailing list<br>><br>> to Send a Message to the list, use the email address<br>> stoves@lists.bioenergylists.org<br>><br>> to UNSUBSCRIBE or Change your List Settings use the web page<br>> http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org<br>><br>> for more Biomass Cooking Stoves, News and Information see our web site:<br>> http://www.bioenergylists.org/<br>><br>><br></div></body></html>