Tom, What you say here makes a lot of sense.
Thanks so much. Paul Olivier On Fri, Jun 28, 2013 at 9:36 AM, Tom Miles <[email protected]> wrote: > Paul,**** > > ** ** > > The typical impact of higher CO2 is to reduce combustion temperatures and > make producer gas combustion less stable. As dilution increases and > temperatures decrease in upper regions I would expect to see an increase in > unburned CO. You should be able to measure differences with a small probe > and thermocouple. **** > > ** ** > > Tom**** > > ** ** > > *From:* Stoves [mailto:[email protected]] *On > Behalf Of *Paul Olivier > *Sent:* Thursday, June 27, 2013 5:04 PM > > *To:* Discussion of biomass cooking stoves > *Subject:* Re: [Stoves] Ph.D. Thesis on TLUD Stoves.**** > > ** ** > > Ron,**** > > When char is consumed in a fan-powered TLUD, several negative factors come > into play. At the point where char is consumed, hot zones are created, > giving rise to temperatures that are truly brutal on all types of metal. As > a consequence of such high heat, the walls of the reactor can be degraded > in a matter of months, often times, in just a few weeks. > > When char is consumed, the descent of the pyrolitic front is not uniform. > The syngas generally contains a lot of CO2. An inefficiency in heat > transfer is created as energy gets released within the reactor at a > considerable distance from the pot. To compensate for this loss in heat > transfer, the operator might increase the speed of the fan, and in so > doing, make matters worse.**** > > If syngas contains a lot of CO2, I wonder how this affects the combustion > CO and H2 within the syngas. If CO and H2 are diluted with CO2, do they > fully combust when exposed to secondary air? Is there a link between the > presence of CO2 prior to the combustion of the syngas and the presence of > CO after the combustion of the syngas?**** > > ** ** > > When char gets consumed, pockets of ash are created, and they might easily > contain high levels of cristobalite. This is especially true in the case of > rice hulls, which contain high levels of amorphous silica. When char gets > consumed, the quality of the biochar produced is compromised. Ash is not > biochar, and biochar is not ash.**** > > Thanks.**** > > Paul Olivier**** > > ** ** > > ** ** > > On Fri, Jun 28, 2013 at 2:43 AM, <[email protected]> wrote:**** > > Julien and list > > 1. Thanks very much for providing this cite. I have read most and find > it to be a well done thesis. I wish we had more like it. > > 2. The concepts of char and TLUDs are in here thoroughly. But nothing on > the idea of a stove designed to make char. All char is presumed and > desired to be consumed. > > 3. My conclusion (would like to hear more) is that a good case is made > (not intentionally) for NOT consuming the produced char in a TLUD (this > one fan-powered and widely sold in India as the "Oorja" (started by BP)). > Very little gain in overall efficiency as the char is consumed. > > 4. A major advance was his study of the importance of ash in this "char" > period as a poor radiator - thereby responsible for (undesired) high char > temperatures. > > 5. Most everything shown as a function of superficial velocity (Vs) - > with 16-17 cm/sec shown as key dividing point in stove behavior.. Above > which velocity one swtches from char production to char consumption. I > have not seen this before. > > For his highly automated fan system, measuring Vs was apparently not > so difficult. Anyone able to give a way to get an easy estimate of Vs, > when there is only natural draft? > > 6. Quite a bit on the importance of low emissions of CO. > > 7. Good information on both the experimental and computational side of > top-lit (packed bed) stoves. Not much here for rocket stoves. > > Have I got #3 right? > > Ron**** > > > _______________________________________________ > 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://stoves.bioenergylists.org/ > > **** > > > > > -- > Paul A. Olivier PhD > 26/5 Phu Dong Thien Vuong > Dalat > Vietnam > > Louisiana telephone: 1-337-447-4124 (rings Vietnam) > Mobile: 090-694-1573 (in Vietnam) > Skype address: Xpolivier > http://www.esrla.com/ **** > > _______________________________________________ > 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://stoves.bioenergylists.org/ > > > -- Paul A. Olivier PhD 26/5 Phu Dong Thien Vuong Dalat Vietnam Louisiana telephone: 1-337-447-4124 (rings Vietnam) Mobile: 090-694-1573 (in Vietnam) Skype address: Xpolivier http://www.esrla.com/
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