[Stoves] Frame stoves and biomass boxes.......was...Re: cook stoves for Cameroon
Anh
ntanh at greengenvn.com
Thu Sep 25 11:18:11 CDT 2014
Dear Paul,
"Frame" is just a translation from Vietnamese name used for the extra metal frame to support large pots (>50 litters). With that metal frame, we can take the stove out, add more fuel without moving the heavy pot which stay on the metal frame.
The biomass box can be in various side and shape, can be just a metal tube (our first tests). We need to seal the bottom of the box to prevent biomass falling out and air getting in. The top of the box can be open but I prefer to have cap with some small holes (3-4 holes at 1cm diameter), with that we can reduce air getting in (to keep the biochar from burning out) and concentrate the gas output and make a longer flame from the holes.
The box side: can be same height with the combustion chamber, the width can be ~ 1/3 of the combustion chamber, so with 2 boxes you can replace ~60% wood with small biomass (burning time will reduce but you can add more wood/main fuel later to extend cook time)
For small tube type box, you can put in as if it is a wood stick. I prefer the square shape box to put on the sides of the square stove, it will only use waste heat that transfer out sideway to heat the biomass inside, it also reduce temperature of the stove's side cover a bit.
Duration of the box varies depending on biomass type, saw dust is the best, can burn for 15-20 min more (after fire from main wood burnt out).
Limitations:
- it's hard to replace biomass box when it burnt out, need extra tool to replace the box when stove is burning hot.
- some biomass burn out too fast: straw, garden leaves,... so cannot use with too small boxes
Here are some picture of the boxes before and after cooking.
Anh
-----Original Message-----
From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Paul Anderson
Sent: Tuesday, September 23, 2014 10:37 PM
To: Discussion of biomass cooking stoves
Subject: [Stoves] Frame stoves and biomass boxes.......was...Re: cook stoves for Cameroon
Anh,
I like your terminology for the "frame stove" that distinguishes it from the "pot on top" (or other name?) stoves.
I am also interested in more details about your "biomass boxes"
> For Rice husk and other small shape biomass, will have to put inside the biomass boxes, which act like a retort to turn these biomass into char.
Please tell us your experiences about sizes, openings, placement into
the micro-gasifiers, duration, etc. etc. and limitations . Photos
would be useful.
Thanks, and keep up the good work!!!!!!
Paul
Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <mailto:psanders at ilstu.edu> psanders at ilstu.edu
Skype: paultlud Phone: +1-309-452-7072
Website: <http://www.drtlud.com> www.drtlud.com
On 9/23/2014 3:34 AM, Tuan Anh wrote:
> Hi Huck,
>
> Pls find below the answers to your questions:
>
> 1/ very easy, just remove the pot and throw wood into the hole on the cap of the stove, same round hole that the fire come out. We have "frame stove" to handle large pots (50-100 litters) you can leave the pot on, pull the stove out to add woods.
>
> 2 charcoal left in tge stove: if it is inside the biomass box, which is air tight, it will not burn out. Charcoal from firewood: just put out the fire by filling dry sand into the stove, it will put fire out and keep charcoal intact.
>
> 3. Normal charcoal stove need force air/fan to burn in maximum level, leaving charcoal inside tlud it will burn out slowly with primary air, as it burn slow, not much heat was generated, only good for some slow cooking, like stew, boiling bones for soups,....
>
> 4. Our stove made from metal plate, it will rusted over time but can
> last about a year at very low cost. Our official retail price is
> only12$ for medium stove (most common for family cooking) some
> retailers sell below that price. Wholesales price only around $7 for
> finished stove, 6$ for unassembled (very easy to assemble our stove
> with just a small power drill and our supplied metal screws)
>
> Best regards,
>
> Anh
>
> On Sep 21, 2014 1:57 PM, Huck Rorick < <mailto:huckrorick at groundwork.org> huckrorick at groundwork.org> wrote:
>> Hi Anh,
>>
>>
>>
>> I was very interested in several questions about your stoves.
>>
>> 1. The website mentions that wood can easily be added to extend burn time. Did I understand correctly? (Since one common concern about gasifier stoves is that they are batch operated and cooking time is not easily extended.) If so, how is that done?
>>
>> 2. The website also says charcoal is left in the stove. Is it left without further attention? In other cases it seems necessary to put the char in an airtight container or to otherwise stop the continued combustion of the charcoal. (Oops, I see that in your note you mention putting out the fire to keep the charcoal. How do you put out the fire?)
>>
>> 3. Your note mentions that you can leave the charcoal in the stove to burn (which seems to answer my question 2, i.e. you can’t just leave the charcoal there, but have to quench it in some fashion). Others have suggested that doing this creates high temperatures in the combustion chamber which leads to rapid deterioration. How do you deal with that?
>>
>> 4. What materials is the stove made of?
>>
>>
>>
>> Thank you very much for your notes.
>>
>>
>>
>> Huck
>>
>>
>>
>> From: Anh [ <mailto:ntanh at greengenvn.com> mailto:ntanh at greengenvn.com]
>> Sent: Thursday, September 18, 2014 4:27 AM
>> To: 'Discussion of biomass cooking stoves'
>> Subject: Re: [Stoves] cook stoves for Cameroon
>>
>>
>>
>> Huck, Ron and list,
>>
>>
>>
>> I am Anh from GreenGenStove in Vietnam, we are making TLUDs and I’d like to share some experience that may help a bit.
>>
>>
>>
>> TLUD made charcoal and my customers can use that charcoal in 2 ways:
>>
>> - Leave it there to burn in the stove to cook something that need long time, low heat (like stews, bones boiling,…) at the end of normal cooking.
>>
>> - Put out the fire to keep the charcoal for later cooking using dry sand or soil.
>>
>> So I am sure that char are accounted for by users.
>>
>>
>>
>> TLUD require to cut fire wood to short pieces to fit in the stove (we got this complain all the time) but it can use many other biomass too, especially corn cobs which is very hard to burn with three stones or some other stove. If you have carpenter workshops nearby, all the little wood junks from the shop can be great fuel, no need to cut and it is much better quality than normal soft wood/branches that normally used for cooking. Saw dust can be great too but you would need extra biomass box (a kind of retort) to use it. TLUD can adjust the fire level (controlling the primary air) and require almost no fire tending so that can somehow obsess the extra time needed to prepare fuel.
>>
>>
>>
>> Another advantage of TLUD is fire up time, for us is less than 30 secs, which impress all the users.
>>
>>
>>
>> We currently working in 12 mountainous provinces in north of Vietnam and the fuel availability, cooking habit are varied from place to place, so we need to learn about the customers before deciding which would be the best selling points to them (among a dozen of advantages of TLUD or any improved cook stove). Changing cooking habit would be the most difficult thing or at least, it will take the most time to change.
>>
>>
>>
>> Regards,
>>
>>
>>
>> Anh
>>
>>
>>
>>
>>
>> From: Stoves [ <mailto:stoves-bounces at lists.bioenergylists.org> mailto:stoves-bounces at lists.bioenergylists.org] On
>> Behalf Of Ronal W. Larson
>> Sent: Thursday, September 18, 2014 11:43 AM
>> To: Huck Rorick; Discussion of biomass
>> Subject: Re: [Stoves] cook stoves for Cameroon
>>
>>
>>
>> Huck, list, cc Paul
>>
>>
>>
>> I read all the good information provided by the young person who answered your questions. Tell him/her that he/she did a good job.
>>
>>
>>
>> The main new information I got was that your part of the Cameroons has to follow a practice of slash and burn. This requires enormous effort - way more I’ll bet than the practice of finding firewood. And the time before needing to slash is probably getting shorter - and little land is probably available to produce cash crops.
>>
>>
>>
>> I suggest you google for the words “slash and char” (especially the website of Dr. Christoph Steiner), “Terra Preta”, “biochar”, etc. The idea of char-making stoves is intimately tied in with the idea of soil improvement - with the most prominent means for low income families in countries like the Cameroons being that of saving the char for placement in soil - to get improvements in yield, but also to avoid having to continually be moving their ag plots.
>>
>>
>>
>> Prof Lloyd has indicated today that char from char-making stoves will be thrown away. Will not happen.
>>
>>
>>
>> More below
>>
>>
>>
>> On Sep 17, 2014, at 8:27 PM, Huck Rorick < <mailto:huckrorick at groundwork.org> huckrorick at groundwork.org> wrote:
>>
>>
>>
>> Hi All,
>>
>>
>>
>> I found myself a little confused by the discussion.
>>
>>
>>
>> Not being expert in the field, this is how I would pose my questions:
>>
>> There is a certain amount of energy per kilogram of wood (I’m going to stick with wood for the moment rather than all biomass).
>>
>> [RWL1: Always very close to 18 MJ/kg if dry. You need to be sure that only dried wood goes into any stove.
>>
>>
>>
>>
>> When burned, some of that energy is realized and some is not, i.e. there is not complete combustion. How complete is the combustion? How much energy is released? That would be the first measure. I want this because it tells me about one component of the system and is useful for design. It does not tell me the net result for the user.
>>
>> [RWL2. The three stone fire might give you only 10-15% efficiency. Improved stoves at least twice that. Part of the loss is in CO and particulates. Char-making stoves usually show up best in EPA testing.
>>
>>
>>
>>
>> How much of the released energy goes into cooking? That would be my next measure. That should tell me what weight of wood people have to collect to cook their food. It is worth noting that the amount of energy that goes into cooking is also affected by the pots and lids used as well as how they fit onto the stove.
>>
>> [RWL3: Plenty of data on this - for both total combustion (look up “Rocket stoves”) and char-making (TLUDs). Yes on your qualifiers.
>>
>>
>>
>>
>> It is also important to know how much energy was expended to get the fuel and prepare it for use. Some of that energy is human energy so it gets treated a bit differently and has a different impact. For example, it doesn’t convert simply to climate impact (are humans low global warming gas emitters?). If you cut up the fuel a lot and process it a lot there is a cost there. I don’t know how that stacks up for gasifiers vs other stoves.
>>
>> [RWL4: For sure the TLUDS will require more effort in fuel preparation. But that also can be balanced if you can avoid slash and burn. Humans are not low global warming emitters. Your village is one of the lowest of course - but there will eventually be some funds transfer to the Cameroons for help in carbon sequestration - with biochar likely to be a least cost way. Cutting wood can be not so onerous if you start with small stuff (branches not trunks). Plan on selling the big trees, not using them for cooking. Also grasses may work where you are.
>>
>>
>> Regarding charcoal. I am presuming you can still use the charcoal. I was, apparently erroneously, under the impression that gasifier stoves could continue to receive primary air and therefore burn the charcoal. I actually liked that idea because it was simple and used most of the energy in the stove. If you take the charcoal out of the stove you then have a couple of options for using it. You can burn it in another stove, which has some appeal as you can do a different kind of cooking with it (e.g. BBQ, or ?). But also seems like quite a bit of work and complication for a small amount of charcoal. Or, you can use it in the soil. So another question:
>>
>> [RWL5: Yes you can use charcoal for cooking - but do not use in the same device used to make it. It is much dirtier and less efficient to use the same stove. But yes to your last sentence on putting in soil. Your “clients” should try it with a few small “holes” - not a whole field. Comparison and experimentation is critical. We know of cases near you that were so positive that theft hindered reporting.
>>
>>
>>
>>
>> Is a gasifier stove with charcoal (biochar) buried actually carbon negative?
>>
>> [RWL6: Yes. Not permanently - but hundreds (maybe thousands) of years is enough to count.
>>
>>
>>
>>
>> Then the other important measure: what are the emissions?
>>
>> [RWL7: There is a ranking system (1:4), with char-making stoves generally the highest. The most recent reporting on this list was about work by Mr. Kirk Harris - generally well over 4.0 But they can be done badly as well.
>>
>>
>>
>>
>>
>>
>>
>> And, a kind of crude question: with the ins and outs of this discussion is it the case that rocket stoves or some other stove is more efficient than the gasifiers? In my question by efficiency I mean kg of wood required for a Cameroonian to cook their meals?
>>
>> [RWL8: Almost certainly the Rocket will use less fuel for cooking. But not true for an exceptional TLUD vs a poor Rocket. But if you get 50% more produce from a garden, many are saying that is a tradeoff worth making (and having the same garden year-after year).
>>
>>
>>
>> Which stove do they have to carry more wood for and do more fuel preparation for? (I’m not sure how you measure the combined work for those tasks).
>>
>> [RWL: Too little knowledge on my/our part of your fuel choices. Maybe there is a waste product all over the place you can be using in a TLUD (and not in a Rocket). Corn cobs? a nice reed? palm waste?
>>
>>
>>
>> There is a serious difference in the time needed to tend a fire in the two types as well - much less for a TLUD. Maybe there is a local need for char - and the sale can justify the extra time spent finding and preparing fuel. There is no such income potential with Rockets. But my main concern is that you apparently have some very poor soil - and the best way I know of to fix that is with charcoal.
>>
>>
>>
>> Ron
>>
>>
>>
>> Huck
>>
>>
>>
>> From: Paul Anderson [ <mailto:psanders at ilstu.edu> mailto:psanders at ilstu.edu]
>> Sent: Monday, September 15, 2014 9:25 PM
>> To: Discussion of biomass cooking stoves
>> Subject: Re: [Stoves] cook stoves for Cameroon
>>
>>
>>
>> Huck,
>>
>> Crispin wrote:
>>
>> Thus ‘gasifiers’ are getting rated as if they do not consume fuel that is actually consumed.
>>
>> Crispin's point is that wood that is turned into charcoal is no longer wood. THAT is true. But there are two ways to state the efficiency: Fuel efficiency and Energy efficiency. Charcoal that is created is no longer wood. But it is a fuel made from wood that was transformed. And it typically represent 25% to 35% of the energy that is in the dry weight of the wood.
>>
>> You indicated that the area is reasonably wooded. So it is not a case of scarcity of wood.
>>
>> If the created charcoal is put into the soil as biochar, then that energy content is no longer available.
>>
>> You as the project leader and with your personnel can make the decision about how to read the numbers in the reports on stove efficiency (of fuel or of energy).
>>
>> Paul
>>
>>
>> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
>>
>> Email: <mailto:psanders at ilstu.edu> psanders at ilstu.edu
>>
>> Skype: paultlud Phone: +1-309-452-7072
>>
>> Website: <http://www.drtlud.com> www.drtlud.com
>>
>> On 9/15/2014 10:45 PM, Crispin Pemberton-Pigott wrote:
>>> Dear Huck
>>>
>>>
>>>
>>> Just one quick point:
>>>
>>>
>>>
>>> “The gasifier, as I understand it, is more efficient and has lower emissions.”
>>>
>>>
>>>
>>> It depends on the test method and the metrics. It is fashionable to use the GACC-WBT and that test does not report fuel consumption, it reports the fuel mass equivalent of the energy consumption, treating charcoal left over as unburned raw fuel (meaning it says the wood was not consumed).
>>>
>>>
>>>
>>> Thus ‘gasifiers’ are getting rated as if they do not consume fuel that is actually consumed. When you assess the performance be sure you are clear on how the method calculates performance and what the metrics are. You may want to measure ( and weigh) fuel needed per cooking cycle rather than use any calculated numbers from a complex test protocol.
>>>
>>>
>>>
>>> For evaluation of performance I recommend the CSI-WHT which is a water heating test (no boiling) and a measure of the raw fuel needed per replication of the cooing cycle. It is used by the WB in the Clean Stove Initiative in Indonesia. Documentation (some anyway) is available.
>>>
>>>
>>>
>>> Regards
>>>
>>> Crispin in Tamil Naidu
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>>
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>>
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