[Stoves] Challenging fuel
Ronal W. Larson
rongretlarson at comcast.net
Wed Dec 17 09:33:44 CST 2014
Dr. Nurhuda cc list
1 For others, there is fairly recent writeup on these stoves by Christa Roth (pp 116-117) in her wonderful book on such stoves. See https://energypedia.info/images/0/05/Micro_Gasification_2.0_Cooking_with_gas_from_dry_biomass.pdf
She also provides websites, such as http://www.primestoves.com/our-stoves/technical-documents/
My recollection of our few informal talks at the GACC meeting with Prof. Nurhuda (organized nicely by Paul Anderson) are very favorable. Prof. Nurhuda has lots to teach us.
2. Prof. Nurhuda, your stoves are approximately three times as expensive as the $10 kerosene stove noted below. Can you give the present prices for the appropriate , biomass and kerosene (say per kg at retail, in both urban and rural markets), and give your estimate (and methodology) of the payback time for your stoves - both with and without sale of the produced char? In a real analysis, economic credit should also be given for the time saved while cooking, so hope you can mention consumer feelings on time saving as well. I am hoping that emphasizing more than first cost can be successful when the difference in first costs probably (??) is made up in a few months.
3. We have heard very little of government purchases of char-making stoves. Any lesson there for other stove companies?
4. On this list, it would be inappropriate for you to be pushing sales of your unit, but the above and questions below are asked only in a technical and collegial sense - so I hope you can brag a little more than you have done in the response below. Congratulations on reaching 20,000 units in your second year!
Ron
On Dec 17, 2014, at 7:46 AM, Muhammad Nurhuda <mnurhuda at ub.ac.id> wrote:
> Dear Prof. Larson,
>
> Thank a lot for mentioning me in your response. I developed the stoves since 2008 and experienced all that have been recently discussed, e.g. smoky transition from pyrolisis to charcoal burning. Our first success with TLUD was our biomass stoves UB-02 and the key mechanisms indeed were very similar with that described by Dr. Crispin, namely...pre-heating.
>
> We have sold more than 20.000 TLUD stoves this year, mainly for government project. There are also retailers, but most people think our stoves are too expensive, therefore it is difficult situation. Buyers want that the stove price should be as low as kerosene stove, less than US$10 each.
>
> We have learned that TLUD are not easily accepted by users, since there are change in the habits that must be introduced. This is the difficult things. Once they know how to operate the stove correctly, most of them use the stove for almost daily cooking.
>
> Kind regards
> M. Nurhuda
>
> On Tue, Dec 16, 2014 at 10:34 PM, Ronal W. Larson <rongretlarson at comcast.net> wrote:
> Marquitusus, Alex, Richard, Dr. Nurhuda, cc List
>
> 1. Alex: I’m sure you have done some testing of this approach for using fines. Any data to report? (What might go wrong?, Maximum number (or density) of “long thin plies”?, quality of the produced char?, etc)
>
> 2. Richard: As our most knowledgeable expert on making briquettes (and maybe something thin like Alex is describing), am I correct in assuming that you can easily put fines into something appropriate for TLUDs? But how coarse can that material be? Is it relatively easy to diminish the size of something hard, as you are minimizing the dimensions of softer material in the nice videos given below?
>
> 3. Dr. Nurhuda: We met at the GACC meeting in Cambodia. Your message (not below, but on this topic) doesn’t send folk to your site for several very nice looking TLUD products available in Indonesia (and more?). This list would benefit a lot from hearing more about your stove. For instance, it seems that you are one of the very few separately controlling primary and secondary air. How important is this feature? Also I see a central structure that is not common; does this supply some air? Are your clients placing char in the ground? Anything more to add about using fines, or material with a wide distribution of sizes? More on your test results from Cambodia - that sound good.
>
> Ron
>
>
> On Dec 16, 2014, at 8:45 PM, alex english <aenglish444 at gmail.com> wrote:
>
>> Marquitusus,
>> If you first have success using your sorted or screened fuel without using the smallest pieces (the fines <3mm) in a TLUD, then you can try adding the fines
>> in a long thin pile placed like a long stick embedded in the regular fuel near the top. The fines behave a bit like a thicker piece and will
>> pyrolyse from the heat after the pyrolysis front has passed. If the fines tend to sift down to much into the regular fuel then a 2cm wide strip of
>> paper could be laid down to act as a floor for the fines. Trial and trial will show you what size of pile and how far from the bottom they
>> need to be for it to work. As long as the surrounding fuel is porous the falling pyrolysis front should proceed passing by the piles of fines.
>> Gas production will vary somewhat when compared to using only optimum sized fuel, but it can still work.
>>
>> Alex
>>
>> On Tue, Dec 16, 2014 at 9:08 PM, Richard Stanley <rstanley at legacyfound.org> wrote:
>> Marquitusus,
>>
>> Here is a hand thresher-masher-chopper device we have been developing initially in collusion with a colleague in the US (Ohio) then in Guatemala and now in Nicaragua with contributions from colleagues in Kenya and the Philippines who are developing their own versions.
>>
>> We use it for reducing and scruffing up materials for use in biomass briquette production but by removing the wire brushes you will have a simple thresher-chopper that would nicely reduce the shells to a desired maximum size. Then, with use of a smaller size hand shaken sieve you can reduce the variation in partical size to whatever range you desire.
>>
>> Here are two short videos showing the elements of the unit, initially in Los Angeles California/ US, and subsequently of the unit in operation in Cuneng, Quiche province, northern Guatemala in 2012. Our current prototype here in Nicaragua, is about 20% cheaper and easier to build and much easier to access for cleanout but we need to really test it out before we can claim any bragging rights..Siilar designs will also be emerging in the mentioned countries in various forms according to what resources they have available and what market needs they are responding to.
>>
>> If you like I can put you on the mailing list for the manuals which is targetted for publoication in June, 2015
>>
>> kind regards,
>> Richard Stanley
>> www.legacyfound.org
>>
>> http://www.youtube.com/watch?v=3AJli5GFhxo
>> http://www.youtube.com/watch?v=xO1plnOK4u8&feature=youtube_gdata_player=
>>
>>
>> ======
>> On Dec 16, 2014, at 5:21 PM, "Marquitusus " wrote:
>>
>>
>> Dear stovers,
>>
>> I send you a picture of the fuel I'm trying to deal with.
>> This is the raw fuel as it is normally sold here. They are almond husks.
>> As you see, it's sizes varies from 1 to 40mm!
>>
>> Maybe people can tell me how this can affect the TLUD design
>>
>>
>>
>>
>>
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