[Stoves] (no subject)

Thu Jan 20 14:39:10 CST 2011

Hi Richard,

I have a related question to this discussion, which I think is interesting.

At CU, we have a Jatropha project that you fielded some questions about a
few months ago.  As I'm sure you've heard, Jatropha seedcake does not burn
well, not even close.  So, one of our questions now is:  what can we do with
this waste stream this is both useful and desirable?

One approach we will test is to carbonize the material and for biochar
briquettes (and a water filter media, etc.).  However, I wholeheartedly
agree with your sentiment on biochar briquettes.  What is your opinion if
the ag-waste doesn't burn well normally?  It still seems a bit contrived,
eh?

I'm looking forward to hearing your perspective.

Cheers,
Boston

On Thu, Jan 13, 2011 at 2:13 PM, Richard Stanley
<rstanley at legacyfound.org>wrote:

> Jessica,
>  Me again, I answered some of these questions to you in a post directly to
> you (as that one  came directly from you) --a few minutes ago, but
> let me add a few comments in reponse to your other questions here...( am
> responding in-kind below...)
>
> On Jan 13, 2011, at 12:33 PM, Jessica De Clerck wrote:
>
>  Hello,
>
> I am looking for some insight into an array of issues around fuel
> briquettes and stoves.  I apologize for the long list!  I am hoping
> Crispin, Dr. TLUD, Richard and others can answer some of these.
>
> *Burning Stalks*
> At Stove Camp 2010, we used TLUDs to burn what I recall were maize stalks
> in Dr. Anderson’s TLUD. It worked great.  However, if maize or sugar cane
> stalks can be burned for fuel, why are people not already using this fuel in
> three stone fires, or are they?  I did not see this in Uganda, but I do
> not know about Haiti or elsewhere (where I will be working soon).  I
> understand that a TLUD or other stoves would do a better job of cleaning up
> emissions. -But if a person had access to free fuel in their fields, I would
> think they must have a good reason for not burning it, even in an open fire.
>
> Does the fact that it burns quicker than wood deter people because it
> requires more effort to feed it constantly into the stove?  Or does it not
> burn as cleanly as wood?
>
> *Consumption Rate*
> Does burning fuel in a TLUD or other stove slow down the rate at which fuel
> burns as compared with fuel burned in an open fire?  It seems to me it
> would because the airflow into the fire would be more controlled in a stove.
>
> *Density*
> This also brings up the question of the density of a fuel briquette.  What
> difference does density make?  It seems like we pay a lot of attention to
> this, but to me it seems the only difference is that the less dense the
> briquette the quicker it will burn. Does a less dense briquette burn hotter
> (assuming identical material is used in each briquette)?
>
> It burns quicker but not necessarly hotter. Density is roughly equivalent
> to duration assuming same blend and stove . Greaster density also equates
> (ex any special starters) to harder start with above assumptions also in
> effect. You 'pays yer money and takes yer choice', eh ?
>
>
> *Briquette Stoves*
> I have recently built another RokStove or Holey Rocket –the side fed rocket
> stove for holey briquettes out of clay and sawdust.  I made it to the best
> specifications I could come up with after considering rocket stove
> principles, which was 9” long, 15” tall, and 5” in diameter both in the
> feeding area and combustion chamber. Once the stove has been fired, these
> dimensions will have shrunk approximately 10%.   This will leave a gap
> between the stove and my 4”x 2” holey (1” hole) briquettes.  I would like
> to know if anyone else has had experience in building or using these stoves
> so that we may share lessons learned.  I already speak with Rok and he’s a
> great help.
>
> Rok is  the guy for this. He speaks of the need to think a lot about
> internal hole size to regulate primary air volume and via my own insight
> gained through such Stoves group luminaries such as Crispin here,
> temperature...The annular space between the OD of the briquettes and the ID
> of the feed tube, is also important.
>
>
> What other stoves have been tested and are recommended for burning holey
> briquettes?  I am assuming unless the hole is used as an air channel as in
> the RokStove, the hole in the briquette makes no difference (for example if
> the briquettes are just put in a pile, or used in a gasifier, because
> otherwise a briquette can be broken into pieces if too large).
>
> Rite-e-o on that one, save the one fact that the hole greatly acceletates
> --and makes more consistent-- the drying rate. Add too, the effect of the
> hole in burning them up right, in the three stove open burn situation. ie.,
> ex any stove surround structure.
>
>
> *Green Charcoal vs. Uncarbonized Briquettes*
> Lastly, has anyone done a study of the emissions from making “green
> charcoal”?  I see what Amy Smith is doing with the kilns to make charcoal
> and the Adam Retort and there seems to be a ton of smoke coming off the
> kilns in the process of making the charcoal.  I understand it is an
> improvement from traditional charcoal making, but I wonder if anyone has
> measured the emissions so that I can compare it to other processes.
>
> Shhh. you are unveiling the big secret  of the carboniser school  here !!!
> We don't want to talk about the smoke and energy losses due to
> carbonisation..not as they occur in the user site and all conditions they
> live with...and after the techies have left and the ted talks and photo op's
> wither from our memories.
>
> But why carbonise at all if you have access to the charcoal crumbs and
> fines and dust found around every charcoal sellers stall everywhere in the
> third world...?  Thie waste accounts for between 15 and 20% of the lump
> charcoal being brought into the stall and sold through it...You blend that
> amount into the briquettes and you double the market for the seller or
> proportionately reduce their demand on charcoal while earning them the same
> income... but I'm being a bi facetious: It makes sence where there is no
> charcoal dust--I guess...
>
>
> Does anyone have recommendations on what raw materials ought to be burned
> in a retort vs. crushed and made into uncarbonized briquettes? I’m
> thinking coconut shells and other hard materials that cannot be crushed
> easily, but I would appreciate more input.
>
>
> Thank you all for you time.
>
> Jessica De Clerck
>
>
>
>
>
>
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-- 
Boston Nyer
Graduate Student
Department of Civil, Environmental, and Architectural Engineering
University of Colorado at Boulder
(585) 503-3459
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