[Stoves] Ph.D. Thesis on TLUD Stoves.

Fri Jun 28 20:27:28 CDT 2013

Tom,

I will soon experiment with gasifying pelleted coconut dust, which has a
high lignin content (> 50%). This should produce a lot of biochar.

Paul Olivier

On Sat, Jun 29, 2013 at 8:18 AM, Thomas Reed <tombreed2010 at gmail.com> wrote:

> Dear Paul, Paul, Ron, and all
>
> It is my experience that both the ND (natural draft) and FA (forced air)
> stoves operated in the Toplit mode give a yield of charcoal of ~ 20%.  This
> is related to the composition of the wood, because there is ~80% cellulose
> and 20% lignin in the wood, and the lignin is the principle precursor of
> the charcoal. This is shown in the burning match...
>
> [image: image.jpeg]
>
> where the cellulose is easily volatalized
>
> C6H10O5 + heat ===> 5CO + CH4 + 3H2. (for instance)
>
> while the lignin (C10H12O3 for instance) is most easily turned into
> charcoal.
>
> One test of this is gasifying mesquite, which is uniquely 65% lignin and
> 35% celluloses.  In this case the charcoal yield was over 30%, well over
> the 20% from most wood.
>
> Thomas B Reed
> 280 Hardwick Rd
> Barre, Ma 01005
>
> On Jun 27, 2013, at 10:02 PM, Paul Anderson <psanders at ilstu.edu> wrote:
>
> Dear Ron,
>
> Paul O.'s comment brought to mind a major difference between ND and FA
> (Natural Draft and Forced Air) TLUD stoves.
>
> I think that when the flow of air (?? and the resultant superficial
> velocity Sv???) is low, the small combustion at the MPF (migrating
> pyrolytic front) is mainly  or perhaps nearly 100% of pyrolytic gases close
> to where they exit from the biomass that is being heated.
>
> But when the flow of air is higher (as in the FA in the Oorja), it is
> possible for the incoming O2 to reach the surface of the newly created char
> layer on the outside of each piece of biomass.   This would result in
> consumption of char DURING the MPF period (which is the foundation of the
> TLUD stove operation),
>
> I have not yet read the thesis (I am working in Uganda right now).
>
> Can you or someone try to get the thesis author into this discussion?  And
> perhaps Dr. Prof. Mukunda also at IISc-Bangalore?   And Dr. Tom Reed?
>
> And CONGRATULATIONS to the new Doctor from all of us on the Stoves
> Listserv.
>
> Paul
>
> Paul S. Anderson, PhD  aka "Dr TLUD"
> Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
> Website:  www.drtlud.com
>
> On 6/27/2013 7:03 PM, Paul Olivier wrote:
>
>    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, <rongretlarson at comcast.net> 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
>>
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>>
>
>
> --
> 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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-- 
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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