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" <[email protected]> To: [email protected] 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, [email protected] <[email protected]> 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" <[email protected]> > To: "Discussion of biomass cooking stoves" <[email protected]> > 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: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > 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 > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists > ..org > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > > > > _______________________________________________ > Stoves mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists.org > > > for more Biomass Cooking Stoves, News and Information see our web site: > http://www.bioenergylists.org/ > >
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