[Stoves] (no subject)

Sun Jan 23 04:23:37 CST 2011

Christa,

Data on use of J seedcake as fertilizer woild be most welcome.  Please do send the link,

Jonathan

From: stoves at foodandfuel.info
To: pietverhaart at bigpond.com; stoves at lists.bioenergylists.org
Date: Sun, 23 Jan 2011 09:52:12 +0000
Subject: Re: [Stoves] (no subject)

To Piet: the composition is not the problem, its the 'bulk properties' related to unshaped seedcake: with the oil the small particles stick and lump together so its too dense to get the air through that is needed for combustion (imagine it like fine sawdust soaked in oil...). if you change the aggregated particle size to make slightly bigger 'lumps' and shape them e.g. by pelletising or briquetting, or you combine it with some more chunky material that still keeps some air-paths open, then it burns really well in a gasifier. you just need to take care of the 'two types of fuels' contained: the solid biomass and the evaporating oils (I am sure an expert can put that in better words), that you need to treat differently to get a clean combustion.

To Boston: on other, non-energy uses: I had a discussion with people from a substantial  J-project in Malawi:  They conisder J-seedcake as a wonderful soil-additive like it is.  they told me it works even without composting it first. they seem to have data on yield increases on maize. If that is of interest, I can link you to them.

regards from Lilongwe, Christa

Am 23.01.2011 um 07:00 schrieb Peter verhaart:

What is the composition of Jatropha seedcake? Probably traces of oil, how about water? A high ash content?
If no water and low ash, it might be the shape of the seedcake, too big, relatively little surface area per volume.

Just a thought.

Peter Verhaart

On 21/01/2011 06:39, Boston Nyer wrote: 

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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University of Colorado at Boulder
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