[Stoves] Mongolian traditional clay stove

[K McLean]

Crispin,

My initial thoughts is this an architecturally beautiful stove.  The most
attractive handmade, homemade stove I've seen.  And it appears to be a very
clean burn.

My suggestion, perhaps wrong, is that it could benefit from a grate under
the dung.

Ron referenced the AgWa stove we are developing.  It is a little early to
bring this up with the stove list but it shows promise.  It is simple and
inexpensive (> USD 2).   A metal cylinder with holes at the bottom is
filled with agricultural waste (eg, maize cobs and stalks).  It's lit on
top so it is a TLUD.  We've found that a little fuel needs to be added to
keep the fire going.  A flame cap makes a clean burn, much cleaner than
three-stone.  Char remains if quenched before burning to ash.  We have
tested this successfully in Uganda and will update.

Kevin


On Mon, May 25, 2020 at 10:56 PM Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Ron
>
> In Tajikistan I was told the agriculture people are very concerned that so
> much Dung is used for fuel, usually necessitated by poverty. What I
> observed is that there is a great deal of work required to prepare,  dry
> and store (meaning move twice) the fuel.
>
> In the traditional stoves, there is prey poor combustion for two reasons:
> the fire is not hot, and the combustion efficient is terrible.
>
> A stove was developed specifically for burning dung more effectively. This
> was classed as the Model 2 in later iterations during the Kyrgyz stove
> project. The final version for heating above 10,000 ft is the KG2.5. It is
> larger, the kind of stove that would be used in Pamir in Tajikistan.
>
> When the fuel is burned badly, it produces a great deal of dung-char. You
> might be surprised to learn that. Chunks or slabs might be heated off-gas
> but not burn well at all. There is a large amount of char that goes to the
> fuel with the ash. The ash is mineral-rich of course.
>
> The new stoves are operated in a very different manner - end-lit
> crossdraft style as per the MM2 from Ulaanbaatar.
>
> The result is a controllable flame, very much better combustion
> efficiency, higher temperatures and better CO combustion. The fuel saving
> is large - maybe 50%. The KG2.5 is about 88+90% efficient (LHV).
>
> So the agriculture people are very happy about this. The fuel use drops by
> half, and the dung is available to be returned to the fields.
>
> The question you might ask is: does adding char from badly burned dung
> bring more benefit to the ecosystem than returning a higher fraction of the
> original material to the soil?
>
> I think the Ag people think that dung is a better offer.  If only half the
> work is needed for fuel preparation and it provides faster cooking, a more
> controllable fire, less chimney cleaning and less 50% transport, it is a
> good choice.
>
> As for the Mongolian vs Tibetan aspect, historically these two are
> strongly connected populations, 600 years ago the Mongolian leaders invited
> Tibetan Buddhists to take over the country and establish a system of
> empire-wide administration which they did. The populations are largely
> indistinguishable. You will recall the various head Lamas like the Dalai
> Lama are often found in the Mongolian population. Six to eight thousand
> years ago when the Earth was much warmer than today, the Gobi Desert was
> fertile grazing land, like the Sahara. It is possible there is no cultural
> difference between the two groups. It was a Turkic Empire in the 6th
> century so I think it is fair to call the stove and the clay dung burner
> "Mongolian" and risk being correct.
>
> Later the leaders invited Russia to come to Mongolia to establish
> communism throughout the country - the only country to join the Soviet
> Union by choice. It is an interesting place.
>
> Regards
> Crispin
> *From:* rongretlarson at comcast.net
> *Sent:* May 25, 2020 9:18 PM
> *To:* stoves at lists.bioenergylists.org; crispinpigott at outlook.com
> *Cc:* ajheggie at gmail.com; info at sun24.solar
> *Subject:* Re: [Stoves] Mongolian traditional clay stove
>
> Crispin,  Andrew, List. Adding Kevin
>
> See a few inserts below - especially on the added information about the
> tray.   Note the material with the video says Tibet, not Mongolia.
>
> On May 25, 2020, at 11:15 AM, Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
> Dear Andrew
>
> I presume the shot at the end showing the smoky modern metal stove against
> the clean flame from the newly built clay stove was to tell us something.
>
>
> The metal stove is a traditional model in used for about 120 year. It is
> ultimately based on a Russian design. It is a great wood stove though not a
> very good dung burning stove.  All stoves that burn dung, save a few, are
> smoky, because they are not idealized.
>
> The metal one in the video is the unit we are trying to get rid of in
> Ulaanbaatar.  Owners take a pretty good wood stove and line it with bricks
> to prevent excessive heat damage, then fuel it with coal for which it is
> hopelessly inappropriate. Lignite actually.
>
> Tell me if the fibres in the dung are to give the clay strength as it
> dries presumaby once it's fired they severe no further purpose ...
>
>
> As explained very briefly in the vide, the fibres prevent or largely
> prevent cracking during drying.  As you can see, the plates are assembled
> as soon as they can be stood up - this is far from ideal.  It would be
> better if they were sub-baked and heated to 500-600 C in a pit using grass
> for fuel.
>
> ...and the clay is held together as earthenware byt the point contact
> partial vitrification?
>
> *[RWL:   My guess is that this is totally unfired.  One of the workers was
> still adding clay as a first fire was lit.  If any Tibetans are
> listening, I hope they add some charcoal to the raw clay next time - likely
> to be stronger - and a better insulator.*
>
>
> Yes.  Similar cookers can be made using termite mounds where the inside
> gets vitrified but the outside never gets hot enough to change at all.
>
> The curious extra piece that the author doesn't know about is possibly one
> of two things: an air guide which means that the stove is probably built in
> a way that the piece is headed into or away from the wind, or it may have a
> spiritual function and always faces East, or South.
>
> The tray on which the yak dung is pre-loaded is most interesting.  Is it
> the first time people have seen such a device attached to a stove?
>
> *[RWL:  Yes - for me - first time.  And clever.   Not looking closely one
> might think also that the two low holes are there for adding fuel.  Not so
> - maybe not even so important for air supply -  they are there for ash
> removal.   *
>
> *The bottom holes can’t be used for adding fuel because of the type of
> fuel - light and fluffy - not stick-like.*
>
> *I bring this up because Kevin McLean has been developing a stove also for
> light material - and is also feeding (in his pre-loading much but adding
> the extras) from the top.  Corn cobs and corn stalks, at least - but there
> are plenty of other non-wood options that are going to waste.*
>
> *Kevin’s interest of course is in making char.  He is calling this an AgWa
> stove (for Ag Waste).  This Tibetan stove wouldn’t qualify (char production
> not being obvious to me).*
>
> *I hope people/places that have other fuels will not turn to burning any
> sort of dung - Yak or otherwise.  Much better to pyrolize it - and make
> money off the char (and combine with other fresh dung in a compost
> operation).*
>
> *I’m afraid I don’t see a way yet to turn this stove into a char-maker.
> But this use of an upper tray is certainly intriguing.*
>
> *Also the use of flat plates in a triangle shape is great to see.  Not
> your usual 45-45-90 or 60-60-60 triangle - but looks close to 40-70-70.
> This caused by the needed tray.*
>
> *The other thing that most impressed me, was that the makers/users
> were obviously very proud of their stove.  Plenty of extra flourishes you
> don’t see in many locally made stoves.  All in all a very well thought out
> design in all respects - obviously not a research project.  I’d like to
> know if this goes back centuries.   A BIG improvement over 3-stones!.
> Efficiency over 15%?*
>
> *Ron*
>
> *Ps.  Thanks to the video producers - who normally are into nomad
> architecture - not stoves.  I hope they can find other unusual nomad
> stoves.  Note this was a 2020 release.*
>
>
>  It allows the fuel to be metered into the chamber "at will" and will
> provide a certain amount of drying (hence the metal).
>
> Yak dung is a widely used fuel.  In the Pamir region of eastern
> Tajikistan, it is the only fuel, save a little oily bush.
>
> Regards
> Crispin
>
>
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