[Stoves] Coal stoves in Mongolia

Tue Jul 26 22:59:33 CDT 2011

Dear Roger (Fireside)

It would be helpful if you put your name at the bottom of your texts because
people are having trouble remembering who sent it.

Regarding the science: ignorance is not a virtue. An ability to learn is.
There is no problem at all that you are not comfortable with the terms used
between guys and gals here who are used to power and efficiency
calculations. If you read this list regularly for a couple of years you can
learn a great deal that will be directly relevant to your stove and efforts.
Apart from technical issues we also discussion funding and program
opportunities, and the risks associated with various stove layouts.

Regarding Mongolia, Ulaanbaatar is the most polluted capital city in the
world, and also the coldest. The people there are mostly very poor (about
660,000 out of 1.1 million) and live in informal housing that has to be
heated for about 8 months of the year. There are enormous forests in
Mongolia that start as the latitude of Ulaanbaatar, but which have
disappeared from the immediate vicinity of the city after 600 years of
cutting, or are protected. There are wood resources available and it is not
even very expensive, however coal is far cheaper and easily available. It is
burned in what is essentially a wood stove and the two fuels are
substantially dissimilar.

If you put diesel into a gasoline engine, it will make a LOT of smoke, not
because the diesel in inherently smoky, but because a gas engine in not
suited to burning diesel well. It needs a completely different type of
hardware. The same applies to coal, and in fact different coals required
different types of combustors. We have specialised at the Asian Development
Bank, the World Bank and the Stove Emissions and Efficiency Testing
Laboratory (SEET Lab) in developing stoves and advising stove producers how
to burn wet lignite (a young brown coal) extremely cleanly. I have not yet
seen a wood stove that will burn as cleanly though I think it can also be
done. It is unlikely that it will be done in the same identical stove, but I
am open minded and will try just about anything. That is how we make
dramatic improvements – not being pre-decided about what works. The same
will apply to you and everyone else.  There are many things possible
.

If you want to try your stove with coal, get the worst, lowest quality coal
you can find. It will have a high level of volatiles in it. Bituminous coal
is a good start. American coals have high sulphur (S) in it so you can tell
how well your stove is doing be measuring the sulphur dioxide (SO2) level
and the hydrogen sulphide (H2S) level (both are cheap to measure) and seeing
the ratio between them. In almost all cases, a domestic stove will burn the
sulphur to one or the other. SO2 is the desired product of combustion. H2S
is not. That is what makes coal stoves stink. If you burn the S to SO2 it
does not smell of rotten eggs. In fact it does not smell of anything if it
is burning well.

The filthy air in UB (as we call Ulaanbaatar) is cause by people placing
fresh wet coal on top of an existing fire. That is the traditional
re-fuelling method. The air in the city peaks at 4200 to 4500 micrograms of
PM2.5 per cubic metre in the open air. The WHO standard for outdoor air is
50. The National standard in Mongolia is 25 so clearly there is a problem.

In the poorest communities 85% of the PM2.5 (particulate matter with a
diameter of 2.5 microns) is from coal combustion at a low temperature. You
cannot see PM2.5 particles. If you see a smokeless fire, perhaps yours, you
cannot tell if it has a high level of PM2.5 or not by looking at it, unless
it is really smoky! If you look at a region with a lot of such stoves from a
distance in sunlight, it will have a white haze. That is reflected light and
you can see it. Of way to tell (without equipment) if you are creating a lot
of small particles is to run the stove in your garage with the chimney
venting into the room. Run it for a while – perhaps 30 minutes making sure
you are not getting sick from the CO or other garbage. Then take a photo of
the stove with and without a flash. If there is PM2.5 in the air, which
might look perfectly clear to your eyes, it will show up in the flash
picture as a slight fog. The non-flash picture will be clearer and not
foggy. Of course that tells you nothing about the quantity of smoke, but it
is a pretty good test you can do with a camera.

While it is interesting that your stove can burn a log slowly, I have been
trying to say that we need a certain quantity of fuel burned efficiently per
hour to get enough heat to keep the house warm.

There is of course a different between temperature and quantity of heat.
Think of a large or small cup of water both at the same temperature. The
larger cup has more heat in it because it has a larger mass that has been
heated to the same temperature.

5 lbs of wood contains about 2.27 kg of wood. If it has a moisture content
of 12% (well air dried) then perhaps the heat content is 17 MegaJoules of
heat (because this is an international list we use metric measurements, plus
Imperial ones like BUTs are hard to work with). 17 MJ is 16,113 BTU’s. That
is a quantity of heat which could be applied to heating a quantity of water
or a volume of air in a room.

So your 2.27 kg of wood has 38.59 MJ of heat in it. If you burn it really
efficiently (say, 99.95%) you can get 38.57 MJ of heat out of the wood.
Burning it fast or slow will make no different to the total heat you get. It
only contains that much. If you need 4 kiloWatts (kW) to heat a home (on a
constant basis, meaning that much is lost through the wall and windows on a
continuous basis) you calculate as follows:

4 kW = 4,000 watts = 4,000 Joules per second. A MegaJoule is 1,000,000
Joules

4,000/1,000,000 = 0.004 MJ per second

You have 38.57 MJ available

38.57/0.004 = 9,642.5 seconds

So if you were to burn the wood at exactly the same rate all the time 5 lbs
of wood would last for 9,642.5 seconds = 160.7 minutes = 2.68 hours.

That of course assumed that the system efficiency was 100% and zero heat was
lost up the chimney which is impossible. If the efficiency is 80%, then the
stove will have to burn at a higher rate to deliver 4 kW and the log will
only last 2.68 x 0.80 = 2.14 hours. Given that the mass of fuel is 2.27 kg,
that is very close to the estimated 1 kg per hour I mentioned yesterday.

If you burn the same log over a period of 10 hours, it can only deliver
2.14/10 x 4kW = 0.857 kW or 857 watts (average). While it is interesting
that you can burn a log so slowly, it is not enough heat to warm a building
when it is cold outside. Most cooking stoves are between 2 kW and 5 kW with
most domestic ones in the 2-3.5 kW range.

The temperature at which the stove burns has nothing to do with the rate of
heat production. It does however relate directly to the cleanliness of the
burn. Low temperature fires usually have high CO and perhaps smoke
particles, though not necessarily the latter. You need a high temperature to
burn CO because it has a high ignition temperature and is inevitably created
when burning any fuel with carbon in it. The environment needed is about 850
C (1560). If you do not burn most of the CO, a great deal of heat is lost
because CO is itself a very high energy gas fuel (better than wood!) If you
lose a kg of Co during a day, you have lost the equivalent of 1.4 kg of wood
as described above so it is a serious business, getting rid of CO and
turning it into CO2.

If you have charcoal left over after the fire, either because it was
deliberately created or just didn’t burn, that has an energy value of about
1.7 kg of wood per kg of char. The discussion your came upon was about
whether or not subtracting char deliberately from the cooking or heating
operation can be met by increasing the efficiency of the cooking (or
heating) or by using something as fuel that was not previously considered
fuel such as grass or wasted twigs (it varies from place to place). My point
was that there is no free energy – if you take char out of what is currently
a wood burning operation, you will either have to get more fuel to replace
it (1.7 kg of additional wood fully burned per kg of char taken out), or
increase the system efficiency (by how much depends on the char yield but
approximately 35%), or find something to burn that is not fuel (which may or
may not be available).

I hope this will assist you in evaluating your stove.

Regards

Crispin

From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Kevin
Sent: 26 July 2011 21:53
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Coal stoves in Mongolia

Dear Fireside

Crispin gave you a typical analysis for the coal he used when he designed,
built, tested, and taught local Mongolians how to build very efficient coal
stoves. Why not start simply by trying to burn local coal in your stove?
Perhaps your stove might not work with coal. It would be good to know this
before you went to the expense of getting a coal sample shipped in from
Mongolia.

Have you tried burning pellets, wood chips, and stickwood in your stove? A
stove designed to burn 5 pound extruded fire logs may not work well on these
other fuels.

Don't underestimate the importance of Science and Measurements as a vital
part of the Art of Stove Design.

Best wishes,

Kevin

----- Original Message ----- 

From: Fireside Hearth <mailto:firesidehearthvashon at hotmail.com>  

To: stoves at lists.bioenergylists.org 

Sent: Tuesday, July 26, 2011 9:49 PM

Subject: Re: [Stoves] Coal stoves in Mongolia

Hello and thanks for responding.

        So lets start with this. I am no where near as educated in the
scientific language as this group, no doubt. What I have created is a double
burn system which can go for up to 12 hours in one 5 lb log. I see NO SMOKE
from our 3"stack once I get to a temperature of over 600 deg. f. Our
secondary combustion temps run in excess of 1500 deg. F. creating a
smokeless burn for hours, and can be reloaded during use. I do realize that
Coal (not a favorite of mine) does burn differently and I would like to test
my stove on this fuel so as to have the chance to tweek my unit to burn it
cleanly. I am reading and trying to understand all that I can. Sometimes I
think that too much science makes things too complex. Maybe being a simple
guy without all the math is what helped me do what I did. Either way there
is no way of getting around the fact that what this stove does do is to get
more heat energy out of the same fuel load, and releasing less into the
environment. Both are characteristics necessary for attacking these issues.
By the way we watched this work in the puget sound area, why could it not
work in Mongolia? 

  _____  

Date: Tue, 26 Jul 2011 02:35:57 +0000
From: rongretlarson at comcast.net
To: stoves at lists.bioenergylists.org
Subject: [Stoves] Coal stoves in Mongolia

Crispin  (cc list)

1.  Changed thread name to reflect the dialog.

  2.  I had great hopes (based on your writings) for a simple Mongolian
BLDD.  Where does that fit into the general scheme for Mongolia?  The BLDD
doesn't seem appropriate for most cooking chores - but seemed pretty perfect
for heating.  (Not thinking about making coke - but there should be that
possibility also    Ron

  _____  

From: "Crispin Pemberton-Pigott" <crispinpigott at gmail.com>
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>
Sent: Monday, July 25, 2011 7:53:14 PM
Subject: Re: [Stoves] WorldStove replies to BioFuelWatyche's
latestimprecisereporting of facts.

Dear Roger

P.S. any idea's how I can get a sample of the coal being used in Mongolia? I
understand they use 4 metric tones a year by 1,300,000 yurts per year. I
think I could cut this down to less than one ton, but need a sample of this
stuff.

Saving coal is not as straight forward as burning less. The need for heat is
absolute, meaning that you have to deliver an average of 4kW minimum into
the home. If the system is 80% efficient it means having a 5kW fire going
constantly.

The number of yurts (gers, as they are called) is about 100,000 with the
number declining slowly as people build more permanent housing. Coal is not
used outside Ulaanbaatar domestically, and in fact viewed historically is
only a recently used fuel.

I am interested in know what you think of as ‘clean’ with your coal burner.
We are expressing the emissions in terms of heat delivered into the home so
that the figure incorporates the thermal efficiency into the number. For
stoves receiving a subsidy to the homeowner, the CO limit is 7 g/MJ
delivered and PM2.5 is 70 mg/MJ. Some stoves are below 1 mg/MJ which is
extremely clean. One is a crossdraft and the other is a TLUD that can be
refuelled under certain circumstances. They are very different to look at.

The coal consumption per urban domestic home is 4,500 kg per year on
average, burning about 1 kg per hour in winter. The coal is from the Nalaikh
Mine, mostly, and the analysis is 25% moisture, 50% volatiles after drying
and 8-12% ash. The sulphur is very low at <0.4%.

It lights easily and has enormous volumes of smoke if placed on a burning
fire (which is the main air quality problem in UB). If a TLUD is refuelled
hot, it is a nightmare. It is essential that the stove be refuelled for
continuous operation. That has led to hopper stoves having the most promise.

The qualifying stoves range from $80 to $160 and one imported TLUD made of
cast iron with a ceramic liner is $275 or so. The cleanest, cheap stove is a
crossdraft burner with a flame tube for the smoke and CO to burn inside the
heat exchanger. This layout has been successful in several very different
products.

Regards

Crispin

> Date: Mon, 25 Jul 2011 06:33:04 +0200
> From: rwhongser at web.de
> To: stoves at lists.bioenergylists.org; crispinpigott at gmail.com
> Subject: Re: [Stoves] WorldStove replies to BioFuelWatyche's
latestimprecisereporting of facts.
> 
> Dear Crispin,
> 
> 2SISTLUDPSXDCPZ-RF
> 
> There, I think we're making progress now.
> 
> Ronald von der AS(BY)EAA
> 
> p.s. Aussenstelle(Bayern)EuropäischeAbkurzungsAmt  /*bitte nicht bei der
EU anzeigen!*/
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: "Crispin Pemberton-Pigott" <crispinpigott at gmail.com>
> Gesendet: Jul 25, 2011 5:36:45 AM
> An: "Discussion of biomass cooking stoves"
<stoves at lists.bioenergylists.org>
> Betreff: Re: [Stoves] WorldStove replies to BioFuelWatyche's
latestimprecisereporting of facts.
> 
> >Thanks for the reminder about names, Andrew. Here's another:
> >
> >I have been trying to characterise the combustion type for the GIZ 7
series coal stoves in Mongolia and it does not fit easily into standard
categories. To make matters worse Prof Lodoysamba has used a true TLUD
charge of coal in the combustion chamber to start the stove and it was very
successful. That means it is a TLUD-ignited cross-draft stove with a
continuously pyrolysing zone at the bottom of a refillable hopper.
> >
> >That to occupy the nomenclaturists for a while.
> >
> >Regards
> >Crispin
> >-----Original Message-----
> >From: "Andrew C. Parker" <acparker at xmission.com>
> >Sender: stoves-bounces at lists.bioenergylists.org
> >Date: Sun, 24 Jul 2011 21:23:57
> >To: Discussion of biomass cooking stoves<stoves at lists.bioenergylists.org>
> >Reply-To: Discussion of biomass cooking stoves
> > <stoves at lists.bioenergylists.org>
> >Subject: Re: [Stoves] WorldStove replies to BioFuelWatyche's
latestimprecise
> > reporting of facts.
> >
> >This is a discussion list. Some of us discuss. Some of us lurk. Some of
> >us know what we are talking about. Some of us wish we knew what we were
> >talking about. Sometimes we don't volunteer a distinction. Some of us
> >act. Some of us act up -- once in awhile. Sometimes things get out of
> >hand, but we get over it -- usually. If you thought the discussion was
> >hot on CAGW and CO2 credits, wait until we start in on nomenclature.
> >Welcome to the list.
> >
> >
> >Andrew Parker (Not AJH)
> >
> >
> >On Sun, 24 Jul 2011 12:34:48 -0600, Fireside Hearth
> ><firesidehearthvashon at hotmail.com> wrote:
> >
> >>
> >> Hello....
> >>
> >> As a new kid on the block I am sorta surprised by the amount of
> >> time spent by people who seem to care, on such a point. You all will
not
> >> agree....probably ever! There, someone said it! Now in the amount of
> >> time wasted, what could have been accomplished through
> >> action........talk is cheap!
> >
> >
> >
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s.org
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> >http://www.bioenergylists.org/
> >
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