July 1999 Gasification Archive

For more information to help people develop better stoves for cooking with biomass fuels in developing regions, please see our web site: http://www.bioenergylists.org

From alkaest at wanadoo.fr Mon Jul 5 09:20:45 1999
From: alkaest at wanadoo.fr (ALKAEST Conseil)
Date: Tue Aug 31 21:36:20 2004
Subject: Sawdust production rate in wood industry
In-Reply-To: <0FDU0018E1GGUL@email.cind.ornl.gov>
Message-ID: <3780B214.B5ACABFE@wanadoo.fr>

Hello

I am undertaking a study concerning the evaluation of some sources of sawdust
used for making wood pellets. I am currently looking for any information
concerning the "average" rate of sawdust production for one cubic meter of
wood machined by the wood industry during each step of the process.
BTW any information concerning the analysis of costs productions of wood
pellets would be much appreciate too !

Many thanks in advance.

Kind regards for France.

Joel Tetard
ALKAEST Conseil
<http://www.alkaest.com>
20 rue de la Liberation
F92500 Rueil-Malmaison
France

Tel : +33 (0)1 41 96 90 70
Fax : +33 (0)1 41 96 90 71
<marketing@alkaest.com>

Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From kchishol at fox.nstn.ca Mon Jul 5 11:53:06 1999
From: kchishol at fox.nstn.ca (Kevin Chisholm)
Date: Tue Aug 31 21:36:20 2004
Subject: Sawdust production rate in wood industry
In-Reply-To: <0FDU0018E1GGUL@email.cind.ornl.gov>
Message-ID: <3780D5EB.A55DBC74@fox.nstn.ca>

Dear Joel

Your question about the percentage of wood ending up as sawdust is very difficult
to answer in an "average" manner. A circular saw may have a kerf as large as
3/8", and if it was used to saw 1" boards, then there would be a 37.5% sawdust
waste factor. On the other hand, if it was producing thick cants for subsequent
resawing on a narrow bandsaw mill, the sawdust percentage would be very much
reduced. The kerf width in a bandsaw resaw mill could be in the range of about
.030", about 1/10 as much as a circular headsaw.

If you are proposing to make pellets from a wood machining operation, the planer
shavings would probably be a much larger percentage of wood waste. However, if
they have a kiln on site for drying the green lumber, then a significant portion
of the wood waste could be required internally, to fuel their kiln system.
Possibly however, they debark the wood, and chip the slabs for external sale, so
that there would be relatively little other waste wood, and much of the sawdust
and planer shvings would be consumed by the boilers supplying heat for kiln
drying.

I would sugest that you would be in a better position if you contacted a suitably
repersentative mill, and get their specific answers to your questions, and then
you could make generalizations that suited your specific purposes.

This is not the answer you wanted, but hopefully it is helpful.

Kevin Chisholm

ALKAEST Conseil wrote:

> Hello
>
> I am undertaking a study concerning the evaluation of some sources of sawdust
> used for making wood pellets. I am currently looking for any information
> concerning the "average" rate of sawdust production for one cubic meter of
> wood machined by the wood industry during each step of the process.
> BTW any information concerning the analysis of costs productions of wood
> pellets would be much appreciate too !
>
> Many thanks in advance.
>
> Kind regards for France.
>
> Joel Tetard
> ALKAEST Conseil
> <http://www.alkaest.com>
> 20 rue de la Liberation
> F92500 Rueil-Malmaison
> France
>
> Tel : +33 (0)1 41 96 90 70
> Fax : +33 (0)1 41 96 90 71
> <marketing@alkaest.com>
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm

From larcon at sni.net Tue Jul 6 08:43:34 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:20 2004
Subject: New member introduction
Message-ID: <v01540b00b3a7a8a25640@[204.131.233.41]>

Stovers: The following exchange should be self-explanatory as an
introduction by someone working on the commercial side of stoves and just
joining our group. Any suggestions for Richard?

Richard: I know that you were not expecting this to go out, but it is an
excellent first introduction. However, please add more that you may have
wished to tell our group. We have had some recent messages about groups
looking for a stove expert - one at least was in Haiti.

Ron

Ronal:

I am presently out of work and trying to get the new stove on the market. I
started working on this type of stove in 1985 and got the patent in 1990. The
name of the original stove is "Volcano" and can be seen at "www.rmvolcano.com"
I licensed the stove to a local company and they are doing well. Since I am
now out of work, I want to try to do something with my new design and am
working on getting the patent for same. I would most certainly be interested
in signing up and collaborating with all of you. Please let me know the
details. You might be interested that I recently designed a hand operated
rotisserie for the stove and yesterday cooked a 7 pound pork roast with about
50 coals. The rotisserie is designed so that you turn it to a position and it
stays there regardless of the balance. I found that turning the meat every 3
or 4 minutes was sufficient. I would love to hear from you and all the rest of
the group. I can imagine what a task it is to provide a low cost solution that
will afford people with various cooking methods where they would be able to
burn any available fuel. The draft system I have come up with supplies
enormous amounts of oxygen into the fire pit by delivering it under the fuel
and all the way around the fire pit. Check out my web site. You will find
some interesting pictures of how the stove can be used. Again, it was great to
hear from you and I would be happy to share some of the things I have
discovered in my pursuit of developing a stove that allows the user to select
the way in which to prepare any food...

Sincerely,
Richard C. Boetcker
rboetcke@bitcorp.net
richard@chrbo.com

P.S. I live in Salt Lake City, Utah and my phone number is 801-566-8753 It
would be great to hear from you this summer sometime. I could fill you in on
some of the other related things I am working on at this time.

Ronal W. Larson wrote:

> Richard -
>
> Two problems
> a, I can't find a (presumed) earlier message from/to you.
> b. I can't open (my fault) your web site. I will try to do that ASAP.
>
> But your message says you should be a list member (no cost). Let
> me know if I should sign you up. Then I would urge an introduction by you
> to the full 160 members on the stoves list. We are about 160 membrs
> worldwide - mostly (but not entirely) working on cheap third world improved
> cooking stoves.
>
> Ron
>

Original message:

> >
> >My Web address is "www.chrbo.com" I think I have addressed many of the
> >concerns related to versatile cooking in any area of the world. With
> >tooling, the price would come down considerably. Maybe we could
> >talk... 801-566-8753
> >
> >Sincerely Richard C. Boetcker
> >
> >P.S I also invented and patented the "Volcano" stove and am now on my
> >own with the new design.
>

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From horster at sover.net Tue Jul 6 08:59:16 1999
From: horster at sover.net (Niko Horster)
Date: Tue Aug 31 21:36:20 2004
Subject: Clay plaster?
Message-ID: <378201A7.34CE8E9@sover.net>

Hi,

After lurking in the dark for most of the past year, understanding
sometimes more sometimes less, I am finally at a point of seeking
advice.

Having built a masonry stove (modified Finnish down draft) with a brick
exterior, I would like to proceed to plastering the outside.

Does anyone know of and/or has tried a plaster recipe which can
withstand the stresses of a masonry heater application?

Thanks you very much

Niko Horster

From larcon at sni.net Tue Jul 6 10:05:18 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:20 2004
Subject: New member introduction - Skye O'Connor
Message-ID: <v01540b04b3a7adb48733@[204.131.233.41]>

Stovers:
Another interesting introduction letter.

Skye:
I have put you on the mailing list.

In late May, we had a very good debate about oven designs between
Dean Still (favoring metal ovens) and Norbert Senf (brick ovens). Let me
know if you can find those through the crest web site - or I can send some
digests covering that topic.

Can you tell us a bit more about your proposed village oven
project. Loaves or kg per day? Every day? How many villages, etc.
Present situation on baking.

Ron

>Ron,
>
>A month or so ago I sent a query r.e. drum ovens into the stoves mailing
>list at Crest. Dean Still contacted me, and I received an email from you
>as well asking if I would be interested in joining the mailing list.
>
>We at ATprojects would love to be put on the mailing list! We have two
>Australian volunteers coming in October to design and build an oven for a
>Village Bakery Development Project, and we want to gather as much
>information and dialogue regarding stoves/ovens as we can.
>
>Are you in charge of the mailing list? If not, can you either let me know
>the email address of the person in charge or send this email on to that
>person? Here is the basic information about us:
>
>Organization: ATprojects
>Email Address: uwo.invest@global.net.pg
>Directors: Steve & Miriam Layton
>Location: Goroka, EHP, Papua New Guinea
>
>Thank you (belatedly) for your response and offer. I look forward to
>corresponding with you in the near future. Please let us know if/when we
>have been put on the mailing list.
>
>-Skye O'Connor
>Project Development Officer

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From larcon at sni.net Wed Jul 7 09:05:03 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:20 2004
Subject: Forwarding New member introduction - Richard Boetcker
Message-ID: <v01540b01b3a9013f79f2@[204.131.233.21]>

Richard - It's best to just address these to "stoves@crest.org". Thanks
for the prompt new additional information. Ron

Stovers - This just received from Richard Boetcker in response to my request:

Here is a bit more information on what I have been doing on stove
development along
with a short bio... Thanks for sending out the word...

To the members:

I have been asked to introduce myself to the group so here goes... My name is
Richard Boetcker and I live in Midvale, Utah. That is just south of Salt Lake
city. I was born in Erie, Pennsylvania and spent 8 years in the US Air
Force. I
have worked at various Computer companies, serving as a course writer and
instructor for the past 33 years. I recently got laid off from my last job
here in
Salt Lake. My involvement in developing a universal stove started in 1985
while I
as in between jobs and continues to this day. I received my first patent
in 1990
and am pursuing a second patent on the improved version of the original
stove. I
granted a non-exclusive licence to a local company and receive royalties on
their
sales of the original design. The original stove is called the Volcano and
can be
seen at “http://www.rmvolcano.com”. The stove was designed to accommodate all
types of cooking implements to include a frying pan, Dutch oven, Wok or
large pot.
It can also be used as a barbecue grill. With the air flow design, the
stove cooks
very efficiently, getting every last btu from each charcoal briquette. When the
fuel is burned, all that is left is a fine ash that can be used in the
garden as a
source of nutrients. I have experimented with other combustibles and in a pinch
and anything that burns will work in the stove. Many of my friends commented on
how large the stove was and that they had problems transporting it to camp sites
and it was impossible to get it into a small camper, boat or land vehicle.
I took
this as a challenge and redesigned the stove so that it collapses into a
space 1/3
the size (16”X16”X5”) of the original, with out compromising any of the original
attributes. In fact, I have added a few new twists. Recently I developed
and had
a prototype made of a hand operated rotisserie and a few days ago cooked a
7 pound
Pork roast, using approximately 50 coals. The rotisserie is designed for easy
loading from the top and it works perfectly no matter if the food is balanced
properly or not. The rotisserie is still in design and is not presently
available
to view on the web site for my new stove. There are also a few other
accessories
in the design stage. I am working on grill lifting handles, a smoker attachment
and a combination draft ring and trivet. The new stove is called the “CHRBO” and
can be seen at the following address “http://www.chrbo.com” Please look at
the web
page and let me know what you think. I am presently looking for the right
company
to help in the mass production of the new stove. This would bring the
price down
considerably. Right now without hard tooling, the cost for the stove alone is
$62.00 in lots of 1000. The carrying bag is included with each stove order. I
would be happy to hear your comments relating to the new stove and will
welcome any
suggestions. It’s great to be a member of the group...

Sincerely,
Richard C. Boetcker
108 Plumtree Lane #19E
Midvale, Utah 84047
Phone 801-566-8753

From woodcoal at mailbox.alkor.ru Wed Jul 7 09:18:15 1999
From: woodcoal at mailbox.alkor.ru (Woodcoal)
Date: Tue Aug 31 21:36:20 2004
Subject: Clay plaster?
Message-ID: <01bec876$fbbb3a00$LocalHost@22>

Dear Niko,
You can apply warmlyproof concrete. The concrete Alax-1300 well works at
temperature of 1300 degrees. Good council about such concrete in your
country can be received at metal-worker or expert in industrial steam
boiler.
Sincerely yours, Yury Yudkevitch, Dr., ass. Prof.
Department of Forest Chemical Technology,
St.-Petersburg Forest Technical Academy(Russia)
----------
>Niko Horster 06.07. 1999. 17:04 about clay plaster<

From larcon at sni.net Wed Jul 7 16:22:17 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:20 2004
Subject: Clay plaster?
Message-ID: <v01540b00b3a966a5549f@[204.131.233.4]>

Dr. Yuri -

Thanks for providing a response to Niko on high temperature
cements. I think it would be very helpful to the full stoves list if you
(and others) could give us a more complete tutorial description of what
needs to be done to produce high temperature concretes - and what leads to
failure.
Can one start with ordinary cement?
Is success in the mix?
If not, where are good sources to buy special high temperature
materials?
Are there any additives that help promote high-temperature lifetimes?
Should one use or avoid steel re-inforcements?
What are upper limits for cements/concretes?
What is considered a good lifetime?

Thanks in advance. Ron

>Dear Niko,
>You can apply warmlyproof concrete. The concrete Alax-1300 well works at
>temperature of 1300 degrees. Good council about such concrete in your
>country can be received at metal-worker or expert in industrial steam
>boiler.
>Sincerely yours, Yury Yudkevitch, Dr., ass. Prof.
>Department of Forest Chemical Technology,
>St.-Petersburg Forest Technical Academy(Russia)
>----------
>>Niko Horster 06.07. 1999. 17:04 about clay plaster<
>

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From woodcoal at mailbox.alkor.ru Thu Jul 8 05:45:41 1999
From: woodcoal at mailbox.alkor.ru (Woodcoal)
Date: Tue Aug 31 21:36:20 2004
Subject: Clay plaster?
Message-ID: <01bec913$b05562a0$LocalHost@22>

Dear Ron,
I not the expert in the field of concrete. I am afraid to be not exact. We
(I and my colleagues) have large good luck this year. A business concern has
paid our works and we have constructed a factory for manufacture of
charcoal. I shall tell about it necessary in detail in autumn. Holiday
beginning at July 5, but we continue to work because continuation of tests.
A factory beginning to work in April and each month makes 70 tons of a
good charcoal. A furnace and other hot parts are built from concrete and
work well.
The concrete has structure Al2O3 - from 38 % (for 1300 degrees C) up to 96 %
(for 1800 degrees). Other components SiO2 from 42 % up to 0.1 %, Fe2O3 from
6% up to 0.1%.&Vcy; concrete add impurity of which English names is not present
in my dictionary. (shamot, boxit, corund such names are on English??).
Franch firm "LAFARGE ALUMINATES" is known by the concrete with temperature
up to 1750 degrees and durability up to 80 N/mm2. The plates
established(installed) vertically or in quality roofs should have the
fixture from steel in the form of hooks attached to a sheet of steel. This
sheet limits a plate outside. This work was made by) the experts, I observed
only and this information all what at me is present.
Yuri

From kchishol at fox.nstn.ca Thu Jul 8 09:00:16 1999
From: kchishol at fox.nstn.ca (Kevin Chisholm)
Date: Tue Aug 31 21:36:20 2004
Subject: Clay plaster?
In-Reply-To: <01bec913$b05562a0$LocalHost@22>
Message-ID: <3784A1EA.903730FB@fox.nstn.ca>

The discussion on "concrete" is perhaps confusing because of language
barriers...

Generally, in America and Europe, "concrete" refers to a construction material
made from Portland Cement, sand, and gravel. When water is added to the dry mix,
it causes the calcium-aluminum-silicate cement to hydrate, and in the process,
form a solid material. This "concrete" is used for building construction, and
has some heat resistance, but under intense heat, it spalls and decrepitates.

"Castable Refractories" can be aluminum silicates, and they have the capability
of being poured into forms, as is "concrete", but when set, they do have
excellent thermal resistance. They can easily withstand temperatures of 2,500 F.
The major consideration when using castable refractories is to slowly bring the
system up to operating tempeature initially, so that excess water can escape
without causing spalling or steam explosions. Once a castable refractory has
been cured initially, it can rapidly be brought back to operating temperature.

A "Ramming Mix" is a refractory mixture, supplied as a formable clay. It is set
in place, then rammed to deform it to the desired shape, and to bond it to other
refractory material. These materials are also good for very high temperatures,
usually higher than castable refractories.

In addition to temperature resistance, chemical resistance and physical strength
are very important factors. Refractory fibre insulation has excellent
temperature resistance, but relatively poor chemical resistance, and relatively
low physical strength. As it applies to wood and charcoal systems, the fibre
insulations are a poor choice if exposed directly to the fuel, in that the wood
ash typically has a significant potassium content, which fluxes the fibres.
However, a castable refractory, or a solid brick of similar chemistry can work
far better in such an application, simply because the very high surface area of
the refractory fibres makes them much more reactive. Another obvious problem
with the refractory fibre is that a log thrown against it will easily damage it.
An "insulating castable refractory" would be a far better choice as a liner for
a wood firebox.

When refractories are purchased from a company selling them, Technical
Assistance is readily available to help with selection of the appropriate
product. However, in developing countries, where it is desired to use indigenous
materials, testing of the materials in actual usage is the best way to go.The
starting point would be to see what materials local people have used for a
similar application in the past. Many "local clays" can serve perfectly well as
refractor liners for coal and charcoal stoves.

Kevin Chisholm

From Reedtb2 at cs.com Thu Jul 8 09:13:17 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: Richard Boetcker Stove
Message-ID: <a7184af1.24b5fe4e@cs.com>

Dear Richard:

The stove sounds great and I'll visit your sites on the web.

However, it sounds like you mostly run it on charcoal. IF that true and how
flexible is it on biomass fuels?

I didn't find your Eaddress in the flurry of postings.

Your truly, TOM REED

PS: I have now checked the sites and it looks like you are primarily burning
charcoal.

Charcoal is a great fuel as far as it goes. Do you know about the charcoal
stoves that Paul Hait makes and sells? They are called PYROMID and you can
find his web site. I ahve one - very nice.

But charcoal preparation wastes 60-70% of the energy in the wood.
At this site we have been exploring CLEAN wood stoves that use all the energy
in the volatiles and may or may not produce charcoal, depending on manner of
use.

I hope you can come visit us - we're only a state away. You can also visit
Ron Larson, our moderator - if you can catch him. He lives 1/2 mile from me
as the crow flies, 5 miles by road.

TOM REED The Biomass Energy Foundation
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From larcon at sni.net Thu Jul 8 12:51:42 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Chisholm on Clay plaster (and more)
Message-ID: <v01540b02b3aa77d6a41a@[204.131.233.7]>

stovers: The following is an excellent response to my specific questions.
This message is different from another "clay plaster" message addressed to
"stoves" by Kevin that came in a little later (that deals with basice
definitions) .

Dr. Yuri: Thank you for your response. This was helpful and seems to
confirm Kevin's additions.

Kevin: Thanks for both messages. Now to give a try at some of these
ideas. A few more questions, triggered by your response and that of Dr.
Yuri:

1) What is the material that is the equivalent of Portland cement
that is used with castable refractories?

Do you know of any case where cast refractories are being used for
low cost rural stoves?

2) Do you or others know of any stove constructions where the
rammed clay is fired in-situ to undergo a high-temperature chemical
transformation, with resultant high strength. I see lots of stoves designs
with pottery-type liners (especially from India), but they seem to have
first been fired in a kiln. One would have to account for the shrinkage,
but perhaps there is some advantage with a first really high temperature
in-situ firing (and I haven't seen this in the stoves literature). Caution
- Sun-dried thin clay pottery is very brittle.
Potters can modify the clay mix to get a physical transformation at
reallly low temperatures (unfortunately also lower strength - but much
better than unfired)

The question really is that rammed clay wouldn't seem to be
sufficiently strong - that brick would generally seem to be superior (or
the slabs of low-cost volcanic material that I saw in Nicaragua).

As my wife is a potter, I know that bringing up to temperature
slowly the first time to avoid spalling is a critical part of the firing
process for all pottery - just as you have said about castable
refractories. As a warning, this also applies to having volatile
impurities (leaves, twigs, etc) in the clay.

Others: Any more data to report ? - maybe especially from developing
countries, as Kevin has suggested. This exchange was in part triggered by
comments obtained when I was last in Ethiopia. What seemed to be an
excellent design for a low-cost modular, factory built cast concrete injera
cooker had been taken out of production because of poor concrete lifetime.

In addition, I saw quite a few badly damaged cast concrete top
stoves in Nicaragua earlier this year. There would seem to be major stove
and refractories marketing opportunities in this technical area.
.

(The rest from Kevin. Ron)

I am sure that others will have a better and more complete reply, but following
are some comments...

Ronal W. Larson wrote:

> Dr. Yuri -
>
> Thanks for providing a response to Niko on high temperature
> cements. I think it would be very helpful to the full stoves list if you
> (and others) could give us a more complete tutorial description of what
> needs to be done to produce high temperature concretes - and what leads to
> failure.
> Can one start with ordinary cement?

Generally, no. There is a lot of "water of hydration" in Portland Cement, and
when heated, the concrete then spalls or explodes.

> Is success in the mix?

The use of portland cement is a basic problem..... the sand and gravel ratio is
not as important to success as is the use of the Portland Cement.

> If not, where are good sources to buy special high temperature
> materials?

This is quite relative..... many common clays can withstand relatively high
temperatures, if brought up to temperature gradually the first time. This allows
the water to escape without causing spalling or steam explosions. Many
clays will
work quite well at stove temperatures. However, because of the infinite range of
clay chemistry, the simplest way to determine if a clay is adequate for the
intended purpose is to try it, and let its performance speak for itself.

To source refractories from commercial sources, look under "Refractories" and
"High Temperature Insulations" in Trade Directories relevant relevant to your
area.

> Are there any additives that help promote high-temperature lifetimes?

Work with as dry a mix as possible, while still being able to form the lining.
Crushed scrap firebrick mixed with the clay will usually improve its refractory
abilities.

> Should one use or avoid steel re-inforcements?

If the temperatures seen by the steel reinforcements are below about 900 degrees
F, oxidation of the steel within the refractory will generally be at a low rate.
If more than 900 to 1100 F, then the steel will oxidize, and the expanded volume
of the scale will usually crack the refractory. If temperatures get
significantly
higher, the iron oxide, which is "basic" will tend to melt and flux "acidic"
refractories, such as silica.

> What are upper limits for cements/concretes?
> What is considered a good lifetime?

I don't know what the "upper temperature limit" would be for a Portland Cement
based concrete at high temperatures. However, the "upper limit" is the
temperature at which one would attain a "good" lifetime for the application.
Hopefully, others can be more specific here.

Sorry I cannot be more helpful.

Kevin Chisholm

From kchishol at fox.nstn.ca Thu Jul 8 14:20:04 1999
From: kchishol at fox.nstn.ca (Kevin Chisholm)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Chisholm on Clay plaster (and more)
In-Reply-To: <v01540b02b3aa77d6a41a@[204.131.233.7]>
Message-ID: <3784ECDC.7C919FED@fox.nstn.ca>

Dear Ronal

> ...del...
> Kevin: Thanks for both messages. Now to give a try at some of these
> ideas. A few more questions, triggered by your response and that of Dr.
> Yuri:
>
> 1) What is the material that is the equivalent of Portland cement
> that is used with castable refractories?

"Refractories" are very broad. In very general terms, there are two types of
binders..... one being sodium silicate, and another being Cr203. The sodium silicate
reacts with the common alumina based refractories, to "stick" them together. I stand
to be corrected on this but the Cr203 is used with magnesia based castable or
ramming mixes, and requires high heat to develop a ceramic bond. Probably the Cr203
refractories use sodium silicate for initial strength, to hold the system together
long enough for the ceramic bond to develop.

> Do you know of any case where cast refractories are being used for
> low cost rural stoves?

I do not know enough about the various stove manufacturers to say, but for sure,
"castable refractories" are used in this application. Local clays ramed into place
are really a "castable refractory" of sorts, in that they are formed in their final
place of use, rather than being pre-fired, and then installed.

> 2) Do you or others know of any stove constructions where the
> rammed clay is fired in-situ to undergo a high-temperature chemical
> transformation, with resultant high strength. I see lots of stoves designs
> with pottery-type liners (especially from India), but they seem to have
> first been fired in a kiln. One would have to account for the shrinkage,
> but perhaps there is some advantage with a first really high temperature
> in-situ firing (and I haven't seen this in the stoves literature). Caution
> - Sun-dried thin clay pottery is very brittle.
> Potters can modify the clay mix to get a physical transformation at
> reallly low temperatures (unfortunately also lower strength - but much
> better than unfired)

In principal, one leans toward a "high strength" refractory, but with high strength
one usually gets brittleness, and a tendancy to crack. As a crude rule, one should
use the lowest strength refractory that is suitable for the application, for cost
considerations, and for "forgiveness considerations." Usually, the lower strength
refractories are not as prone to cracking from thermal stresses, and usually, they
have less heat conductivity. (ie, beter insulating properties.) If they are a bit
"tight" in the stove or furnace, then often they can crush internally to confirm to
the furnace enclosure. "Strong" is not always 'better."

Clays fired in place should include some provision for expansion.... one simple way
is to use a cardboard liner which will burn out and leave space as the furnace comes
up to temperature, and provide for expansion, to minimize thermal stresses.

> The question really is that rammed clay wouldn't seem to be
> sufficiently strong - that brick would generally seem to be superior (or
> the slabs of low-cost volcanic material that I saw in Nicaragua).

Strength is necessary to resist abrasion and physical loads. With clever design, the
loads due to physical weight and to thermal stresses can be minimized, so that it is
basically a question of impact from the fuel being thrown in. A designer should
visualize how the rammed clay will expand in the enclosure, and he can usually
anticipate where there will be a tendancy for stress concentration. With a low grade
and weak material, simply enlarging the cross-section of the refractory can often
lower local stresses to acceptably low levels.

> As my wife is a potter, I know that bringing up to temperature
> slowly the first time to avoid spalling is a critical part of the firing
> process for all pottery - just as you have said about castable
> refractories. As a warning, this also applies to having volatile
> impurities (leaves, twigs, etc) in the clay.

Fine sawdust added to clays will tend to make the final product less dense, and
therefore a better insulator; as the sawdust burns off, the increased porosity
reduces thermal conductivity of the overlall clay mass. Obviously, however, this
will result in a weaker product, but this may not be a problem, for reasons as noted
above.

> Others: Any more data to report ? - maybe especially from developing
> countries, as Kevin has suggested. This exchange was in part triggered by
> comments obtained when I was last in Ethiopia. What seemed to be an
> excellent design for a low-cost modular, factory built cast concrete injera
> cooker had been taken out of production because of poor concrete lifetime.

You mean "castable refractory?" ;-) Perhaps they should simply try another source
for their castable refractory. Depending on the actual mode of failure, perhaps a
redesign of the refractory cross-section and/or the casing would eliminate the
problem, even with the previous castable.

> In addition, I saw quite a few badly damaged cast concrete top
> stoves in Nicaragua earlier this year. There would seem to be major stove
> and refractories marketing opportunities in this technical area.

Perhas these refractories were "too strong", and simply lacked the ability to
withstand thermal stresses. High silica refractories have a phase transformation
around 1200 to 1500 F, where there is a major thermal expansion/contraction effect;
perhaps they simply had too much silica in them.

Kindest regards,

Kevin Chisholm

....del...

From Reedtb2 at cs.com Sat Jul 10 08:28:00 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Chisholm on Clay plaster (and more)
Message-ID: <ef286381.24b896ae@cs.com>

Dear Kevin, Ron et al:

Let me add at least 2c worth to this discussion of stove insulation. (I have
said some of this before, but no one listens).

1) The word "Refractory" is rather vague, but implies the ability to
withstand high temperature and provide SOME insulation. However the thermal
conductivity of ceramics is rather high and they crack. It is too bad that
clay is so universally available and easily worked, since it is NOT a very
good material for stoves and furnaces.

2) The words "thermal insulation" implies the ability to withstand some
degree of heat and also to have a very low thermal conductivity. At
temperatures above 500 C, radiation is the primary heat loss mechanism and
increases as the fourth power of absolute T.

Heat loss can be reduced by heat shields surrounding the hot item. In the
limit each heat shield reduces heat loss to1/2, so in the limit n black body
shields around a body reduce heat loss by a factor of 1/n. Heat shields work
even better if they have low emissivity e , so n reflective heat shields
reduces loss by e/n. I have pioneered multi heat shield and reflective
shielding at MIT in the 1960s and 70s. We built tungsten heater furnaces
that could reach 2500 C using various arrangements of tantalum shields. I
also patented a gold transparent furnace insulated with a layer of gold 100
atoms thick. It had only one shield, the gold, but with e = .01 in the infra
red- equivalent to 100 heat shields. It operates nicely at 1000 C on < 1 kW
and you can see everything inside.

3) Fibrous insulation acts like a multitude of heat shields without the fuss
of nesting. Fiberglass works well at room temperature, mineral wool to
intermediate temperature, and spun mullite (Kaowool etc.) to 1600 C.

The fibrous insulation can be compressed into boards and tubes - the "riser
sleeves" used in foundries among others and I use these materials when I want
REAL insulation - not just refractory. They are soft, easy to cut with a
razor knife, but can be rigidized with colloidal silica. No cracking, but
obviously not meant to withstand heavy abrasive use.

The fibrous insulations have made possible the "self cleaning ovens" that
have taken the market in the U.S. They will go to 600 F, 280 C with the less
power than formerly required to cook at 450 F, and when not in self
cleaning mode, use much less power for the same temperature.

So, in many applications consider using fibrous insulation in part or alone.

Yours truly, TOM
REED
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From Reedtb2 at cs.com Sat Jul 10 09:33:35 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: GAS-L: Re: biomass composition database
Message-ID: <e6005f85.24b8a613@cs.com>

Dear Bram and Tom:

We include a well referenced 160 item biomass database in our book "Thermal
Data for Natural and SYnthetic Fuels", S. Gaur and T. Reed, Marcel Dekker,
1998. In addition there is graphical TGA data on about 100 items, many
analysed as well by NREL. I am enclosing our database on an Excel file.

The data base includes both the measured and calculated High Heating Value of
the fuels. The calculation uses the Channiwala equation,

HHV(kJ/g) = 0.3491 C + 1.1783 H - 0.1034 O [ + 0.1005S -0.0151N -
0.0211 Ash]

It is better than the Dulong, Tillman, IGT or Graboski equations at relating
the HHV to the Ultimate analysis, giving an average absolute error of
prediction of 1.45%.

If you incorporate our data into your larger database, you should consider
including calculated as well as measured HHValues. While a measured value
may be preferred in general, application of this formula will uncover bad
measurements and outliers. It can also be used conveniently in modelling and
prediction.

Congratulations on getting all this data together for the use of the biomass
community.

Yours truly, TOM REED
THE BIOMASS ENERGY FOUNDATION

PS: Just looked at Phyllis.... she (?)'s GREAT. One minor caveat: I looked
at shells - came up shells and husks. It would be good to separate these
two. Shells are typically quite low in ash, husks are typically quite high,
so not good to average the two groups together.

~~~~~~~~~~
In a message dated 7/9/99 9:30:31 AM Mountain Daylight Time,
tmiles@teleport.com writes:

<< Bram,

Thank you for a very useful contribution to bioenergy. I found the database
easy to use. By working with it I am sure that we will find new information
needs to fill.

Our fuel sampling from the alkali deposit investigation (1990-1995) has
expanded into larger, more complete databases through the efforts of EPRI,
NREL and others. A useful IEA activity would be to help your database
become a common library. Of course the various organizations would have to
provide their approval and manpower to put the infomration in a format that
is readily integrated into your database.

Regards,

Tom

At 04:58 PM 7/9/99 +0200, Bram van der Drift wrote:
>Dear members,
>
>Since the beginning of May this year, a database on the composition of
>biomass and waste is available on the internet. Starting with the TU
>Wien database, ECN added many (public and never published) analyses and
>made what's called Phyllis. It's available on the internet on:
>www.ecn.nl/phyllis. Not only one can find data on individual materials,
>also average values for any group of materials (either "standard"
>groups or user defined) can be obtained from the Phyllis database.
>
>The database has been partly financed by Novem, the Dutch agency for
>energy and environment in Utrecht and contains over 1400 records of
>many different materials and is still growing. If you think you have
>data that can be added to the database, please send it to me.
>
>Bram van der Drift
>Netherlands Energy Research Foundation (ECN)
>P.O. Box 1
>NL 1755 ZG Petten
>the Netherlands
>tel: (+31) 224 564515
>fax: (+31) 224 563487
>vanderdrift@ecn.nl
>biomass@ecn.nl
> >>
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From larcon at sni.net Sun Jul 11 01:41:01 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Fred Kuzel on pelletization
Message-ID: <v01540b00b3ac466ac3b4@[204.131.233.11]>

(Stovers: The following came in response to the query from Joel Tetard: Ron)

The Great Lakes Regional Biomass Energy Program produced a "Wood
Pelletization Sourcebook" that describes the costs and processes for making
pellets from sawdust and other wood waste products. Please let me know if
you would like me to mail you a copy.

-Fred Kuzel, Director
Great Lakes Regional Biomass Energy Program
fkuzel@cglg.org

-----Original Message-----
From: owner-bioenergy@crest.org [mailto:owner-bioenergy@crest.org] On Behalf
Of ALKAEST Conseil
Sent: Monday, July 05, 1999 8:25 AM
Cc: Stoves@crest.org; bioenergy@crest.org
Subject: Sawdust production rate in wood industry

Hello

I am undertaking a study concerning the evaluation of some sources of
sawdust
used for making wood pellets. I am currently looking for any information
concerning the "average" rate of sawdust production for one cubic meter of
wood machined by the wood industry during each step of the process.
BTW any information concerning the analysis of costs productions of wood
pellets would be much appreciate too !

Many thanks in advance.

Kind regards for France.

Joel Tetard
ALKAEST Conseil
<http://www.alkaest.com>
20 rue de la Liberation
F92500 Rueil-Malmaison
France

Tel : +33 (0)1 41 96 90 70
Fax : +33 (0)1 41 96 90 71
<marketing@alkaest.com>

From elk at net2000ke.com Mon Jul 12 13:24:23 1999
From: elk at net2000ke.com (Elsen Karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Update on Briquetting Charcoal Powders
Message-ID: <199907121723.UAA00738@net2000ke.com>

From elk at net2000ke.com Tue Jul 13 09:10:07 1999
From: elk at net2000ke.com (e. karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Briquetting with Stearic Acid
Message-ID: <v01510101b3b1099c5345@[195.202.65.192]>

It works very well indeed!

I know that there's a lot of resistance to 'petrochemical additives' in
charcoal briquettes- but there's a reason or two I now see.

Briquetting unmilled carbonised sawdust with up to 25% clay alone resulted
in unsatisfacory binding and a helluva lot of friction- the equipment,
whether manual ram or motorised screw extrusion, just couldn't cope with
the high resistance.

Seems that just a little grease in the system, as provided for by 0.5%
stearic acid (reasonably cheap here at USD equiv. $1.60 per kg), along with
my 25% clay binder as usual, provides for improved binding plus increased
densification and reduced friction (which amounts to lowered equipment
wear, I'm sure). The cost is less than one U.S. cent per kg.

Does anyone know of a 'down side' to the use of stearic acid, or a possibly
cheaper substitute? Stearic acid is used as a wax hardener in candles- the
only use I'm familiar with.

I don't need to use this in my vendor's waste briquettes, but it looks like
it's indispensible to briquetting carbonised sawdust.

elk

~~~~~~~~~~~~~~~~~~~~:
E.L. Karstad :
P.O. Box 24371 :
Nairobi, Kenya :
Fax/tel 884437 :
elk@net2000ke.com :
~~~~~~~~~~~~~~~~~~~~'

From kchishol at fox.nstn.ca Tue Jul 13 09:37:55 1999
From: kchishol at fox.nstn.ca (Kevin Chisholm)
Date: Tue Aug 31 21:36:21 2004
Subject: Briquetting with Stearic Acid
In-Reply-To: <v01510101b3b1099c5345@[195.202.65.192]>
Message-ID: <378B4245.A733A3C9@fox.nstn.ca>

e. karstad wrote:

> It works very well indeed!

...del..

> Briquetting unmilled carbonised sawdust with up to 25% clay alone resulted
> in unsatisfacory binding and a helluva lot of friction- the equipment,
> whether manual ram or motorised screw extrusion, just couldn't cope with
> the high resistance.

While you may not see it yet, this will also likely lead to rapid wear.

> Seems that just a little grease in the system, as provided for by 0.5%
> stearic acid (reasonably cheap here at USD equiv. $1.60 per kg), along with
> my 25% clay binder as usual, provides for improved binding plus increased
> densification and reduced friction (which amounts to lowered equipment
> wear, I'm sure). The cost is less than one U.S. cent per kg.
>
> Does anyone know of a 'down side' to the use of stearic acid, or a possibly
> cheaper substitute? Stearic acid is used as a wax hardener in candles- the
> only use I'm familiar with.

What about using tallow from the rendering of local animal fats? It would
probably be cheaper still, and easier to mix in. ( I would imagine that it is
difficult to uniformly blend in .5% stearic acid with the carbonized
sawdust/clay mixture.) The only downside I can see is that too much may lead to
a smoky condition.

Kindest regards,

Kevin Chisholm

From elk at net2000ke.com Tue Jul 13 12:58:06 1999
From: elk at net2000ke.com (Elsen Karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Briquetting Charcoal with Stearic acid
Message-ID: <199907131702.UAA32685@net2000ke.com>

Second batch was run with 0.5% and turned out nearly as good as the first. I think I'll stick to this lower (and less expensive) rate of inclusion.Once the charcoal is dry, I'll do some burning trials, but I do not anticipate smoke.rgds;elk~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Elsen L. Karstad , P.O. Box 24371 Nairobi Kenyaelk@net2000ke.com tel/fax (+ 254 2) 884437

From Reedtb2 at cs.com Sat Jul 17 15:39:20 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: Fwd: Zmart Ztove
Message-ID: <3d7b3333.24c2364e@cs.com>

Stovers: FYI

Hello Tom Reed,

Thank you for the info about Zmart Ztoves. I phoned the 800# and a
recorded message told me to leave my name and address for a catalogue.
So I did. When the catalogue comes, I will give you the latest about the
stoves.

I appreciate your help in this matter.

Thanx, E. Duffy

Dear E.D.:

The last time I heard from the Zsmart Zstoves they were located at ZZCORP;
10806 Kaylor St., Los Alimitos, CA 90720; 1-800-594 9046;
czport@mail.calypso.com.

Let me know if you find better information.

Thanks, Yours truly, TOM REED BEF

In a message dated 7/14/99 1:26:38 PM Mountain Daylight Time,
duffyfla@ewol.com writes:

<<

To: Tom Reed

Trees for the Future tells me that the Zmart Ztove is available for $20
and refers inquiries to you. Where can I buy this stove?

Thank you,
E. Duffy

To: Reedtb2@cs.com
Subject: Re: Zmart Ztove
From: Emily Duffy <duffyfla@ewol.com>
Date: Thu, 15 Jul 1999 19:37:12 -0400
References: <b249b421.24bf52be@cs.com>
Reply-To: duffyfla@ewol.com

Hello Tom Reed,

I appreciate your help in this matter.

Thanx, E. Duffy

From kip69 at hotmail.com Sun Jul 18 01:03:58 1999
From: kip69 at hotmail.com (Kip H)
Date: Tue Aug 31 21:36:21 2004
Subject: Quick question.
Message-ID: <19990718050552.86512.qmail@hotmail.com>

Hi. I am on an Anthropology field school touring Thailand, Malaysia, and
Bali. Do we have any active members there that would like a visit from a
student, or a group of students?
Thanks
Kip

ps. this is my first post so please let me know if I break any rules.
pps. I am a 4th year Anthropology major, Geography minor student from
Malaspina University / College in Nanaimo, B.C., Canada.

______________________________________________________
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From dstill at epud.org Sun Jul 18 13:54:10 1999
From: dstill at epud.org (Dean Still)
Date: Tue Aug 31 21:36:21 2004
Subject: Zmart Ztove
Message-ID: <000a01bed148$88ec7180$a60e66d1@default>

Dear Tom Reed:

Aprovecho did an early study of the Z or Zip stove, one without a battery,
top loading with a chimney featuring preheated air input. The stove is about
12" high and six inches to a side.

It's a great little stove. We still have a few floating around the shop. You
can see little blue jets of flame next to the preheated air inlets.

The only downside to the stove is that you have to remove the pot to feed
wood and the wood needs to be cut into very short pieces to fit down the
chimney. But it is the best example of preheated air that we have. Making
tea with it is one of my favorite assignments to stove design students here.

Dean Still
Aprovecho

From Reedtb2 at cs.com Wed Jul 21 09:23:23 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: Zmart Ztove
Message-ID: <a90dad4f.24c723ae@cs.com>

Dear Dean and STOVES:

I was very sorry when Fred Hottenroth died last year in his mid '90s. (I
intend to live > 100, so study those who make it.)

The Zip stove is indeed a great stove - as far as it does. They also brought
out the GASFIRE stove, a top lighting variety of the ZIP. However, the best
one is the SIERRA which uses one AA battery to get real forced convection
power out of wood burning.

Natural convection is a great free blessing - but doesn't cut it in cooking.
If you want to

o burn efficiently

o burn intensely for more rapid heating (and thus fuel saving)

o burn cleanly

you need forced convection.

If you are ever in the Denver area come see our "Turbo" stove. It uses 2
Watts of electric power (or equivalent in forced convection from bellows,
windup etc.) to generate 3 kW of cooking power - about the same as a gas or
electric stove. You should see the little blue jets that a pressure of 0.1
inch water column generates!

The Turbo stove can be lit in the kitchen (or corporate board room), cook for
10-50 minutes and be extinguished without odor or emissions (or setting off
smoke alarms). Doesn't leave bottom of pot dirty. Should sell for under
$20. Can be made from tin cans in developing countries.

We'll be presenting a paper on the Turbo stove at the 4th BIomass of the
Americas conference in Oakland Sept. 2.

I'd love to visit Aprevecho if I'm ever in the neighborhood.

Yours truly, TOM REED
BEF

In a message dated 7/18/99 11:58:55 AM Mountain Daylight Time,
dstill@epud.org writes:

<<
Dear Tom Reed:

Aprovecho did an early study of the Z or Zip stove, one without a battery,
top loading with a chimney featuring preheated air input. The stove is about
12" high and six inches to a side.

It's a great little stove. We still have a few floating around the shop. You
can see little blue jets of flame next to the preheated air inlets.

The only downside to the stove is that you have to remove the pot to feed
wood and the wood needs to be cut into very short pieces to fit down the
chimney. But it is the best example of preheated air that we have. Making
tea with it is one of my favorite assignments to stove design students here.

Dean Still
Aprovecho >>
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From english at adan.kingston.net Thu Jul 22 22:00:02 1999
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:21 2004
Subject: Turbo Stove
In-Reply-To: <a90dad4f.24c723ae@cs.com>
Message-ID: <199907230202.WAA19235@adan.kingston.net>

Dear Tom and all,
It is good to hear that the Turbo stove project is progressing. Has it
changed much since I was treated to a demonstration last fall?

This is a stove that truly performs at a much higher level than
anything else that I have seen. Although I don't have any hard proof.
I look forward to the release of some test data.

Correct me if I am wrong, but the Turbo is very fuel size dependent.
Coupled with the need for a small amount of power, this stove is
targeted for people, who could be crudely described as, in the
lower-middle classes of the "developing" world.

I still think that the principles behind the Turbo, top-down
pyrolysis of dry small dimensioned biomass, could be important to the
people who can not use a Turbo stove. Many already use charcoal for
cooking. That charcoal needs to be made by enterprises already using
wood for heat energy. The flared gasses of charcoal production
replace the total combustion of wood products and the by product
charcoal replaces the charcoal which is currently made using wasteful
polluting methods.

I am sure there are cultural reasons why this is easier said than
done, but I just like to keep pointing out that it remains
technically feasible and environmentally desirable.

I look forward to obtaining a Turbo stove. I would like to do some
particulate matter testing of one. Perhaps testing it in comparison
to a charcoal burning stove which is the "cleanest" (Carbonmonoxide
aside) that I have tested.

Yours, breaking silence..... Alex

From tmiles at teleport.com Thu Jul 22 22:55:51 1999
From: tmiles at teleport.com (Tom Miles)
Date: Tue Aug 31 21:36:21 2004
Subject: Turbo Stove
In-Reply-To: <a90dad4f.24c723ae@cs.com>
Message-ID: <4.2.0.58.19990722195816.026b9940@mail.teleport.com>

Alex,

I share your enthusiasm for the Turbo stove. When I visited Golden this Spring Tom cooked part of our dinner on the stove. Very impressive and needing to be widely used once it sees commercial daylight.

Prepared fuel is as important as ever but the concept works. We need to explore its boundaries.

Regards,

Tom Miles

At 10:02 PM 7/22/99 -0500, *.English wrote:

>Dear Tom and all,
>It is good to hear that the Turbo stove project is progressing. Has it
>changed much since I was treated to a demonstration last fall?
>
>This is a stove that truly performs at a much higher level than
>anything else that I have seen. Although I don't have any hard proof.
>I look forward to the release of some test data.
>
>Correct me if I am wrong, but the Turbo is very fuel size dependent.
>Coupled with the need for a small amount of power, this stove is
>targeted for people, who could be crudely described as, in the
>lower-middle classes of the "developing" world.
>
>I still think that the principles behind the Turbo, top-down
>pyrolysis of dry small dimensioned biomass, could be important to the
>people who can not use a Turbo stove. Many already use charcoal for
>cooking. That charcoal needs to be made by enterprises already using
>wood for heat energy. The flared gasses of charcoal production
>replace the total combustion of wood products and the by product
>charcoal replaces the charcoal which is currently made using wasteful
>polluting methods.
>
>I am sure there are cultural reasons why this is easier said than
>done, but I just like to keep pointing out that it remains
>technically feasible and environmentally desirable.
>
>I look forward to obtaining a Turbo stove. I would like to do some
>particulate matter testing of one. Perhaps testing it in comparison
>to a charcoal burning stove which is the "cleanest" (Carbonmonoxide
>aside) that I have tested.
>
>Yours, breaking silence..... Alex
>
>Stoves List SPONSORS and ARCHIVES:
>http://solstice.crest.org/renewables/stoves-list-archive/
>Stoves Webpage
>http://www.ikweb.com/enuff/public_html/Stoves.html
>For information about CHAMBERS STOVES
>http://www.ikweb.com/enuff/public_html/Chamber.htm

From Reedtb2 at cs.com Fri Jul 23 09:05:52 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: Natural and forced convection....
Message-ID: <7839b56f.24c9c324@cs.com>

Stovers:

Re my recent post on our Turbo Stove:

Fans typically put out great quantities of air at < 0.1 inch water pressure.
Blowers put out lesser quantities, but at up to 10 iwp. Important
distinction. But natural draft generates only 0.01 iwp per foot of chimney,
so a 6 inch flame is pretty lazy.

T. Reed BEF
Stoves List SPONSORS and ARCHIVES:
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http://www.ikweb.com/enuff/public_html/Chamber.htm

From larcon at sni.net Fri Jul 23 18:59:07 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Wilkerson on job in Haiti
Message-ID: <v01540b02b3bea4c6500e@[204.131.233.38]>

Stovers - The following is being forwarded on behalf of Rona Wilkerson.
Contact her for details that did not come through well to me. Ron

(The rest from Rona)

Dear all,

I am posting with regard to a job placement in Haiti. It is initially a one
year placement, based in Port-au-Prince, Haiti, due to start in September.

The project has been on going for 4 years and the Project Manager is
responsible for developing and implementing a Household Energy Program.
This includes promoting improved charcoal stoves; (2) improving energy
efficiency in small industries including School Canteens, Restaurants and
Bakeries; (3) developing and promoting the National Household Energy
Strategy by reviewing and updating information on the household energy
situation, publishing results, identifying and assessing new technologies
and approaches including Kerosene and Gas Stoves: (4) working with local
NGOs and Government Ministries such as the BME, to strengthen their
capacity to design, plan and implement successful projects.

If anyone is interested, and has experience in the field of
biomass/household energy, please contact me as soon as possible.

I have attached a Word document with some further information (and more can
be obtained from me)

Many thanks,

Rona

Dr Rona Wilkinson
Energy and Environment Programme Manager
Intermediate Technology Consultants Ltd
Schumacher Centre for Technology and Development
Bourton Hall, Bourton-on-Dunsmore, Rugby CV23 9QZ UK
Tel: +44 -1788 661103 Fax: +44 -1788 661105
http://www.oneworld.org/itdg
http://www.itdg.org.pe

From Reedtb2 at cs.com Sun Jul 25 09:50:47 1999
From: Reedtb2 at cs.com (Reedtb2@cs.com)
Date: Tue Aug 31 21:36:21 2004
Subject: Turbo Stove
Message-ID: <ac0367dc.24cc7093@cs.com>

Dear Tom, Alex et al:

I had a MOST interesting day in STOVES/GASIFICATION yesterday in Ward, Co.

Ward is on the Peak to Peak Highway, 20 miles West of Boulder, 1 mile higher
and 100 years earlier than Boulder, CO (10 square miles surrounded by
reality). Typically when Denver gets too crowded and too regulated,
adventurous souls move to Boulder; when Boulder is TCTR they move on to
Nederland; when Nederland is TCTR they move to WARD where anything goes in
alternate lifestyles, but no normal lifestyles exist.

Our good friends Steve and Linda Schweim are remodeling the kitchen, 2020
style (after cheap oil). Steve is a cabinetmaker so has plenty of wood.
They have put in a kitchen range with THREE turbo burners and have been
cooking all their meals on it now for a month.

Yesterday Agua Das and I went to the TURBO stove "coming out" party with
other friends of theirs. One is Russ Peterson, former Dupont Chemist, Gov.
of Deleware, head of the Council on Environmental Quality under Carter...
etc. (He has just finished a book "Rebel with a Conscience" giving details).

The lunch was delicious and the talk was even better and the thunder and
lightening was close to heavenly. (Our dog, Lucy roams the town freely,
checking out the many dogs in dog heaven).

In particular they had built half a dozen other models of Turbo stoves using
square tea cans etc. So it was nice to have others working on the
configuration of primary and secondary air holes etc. etc.

We hope soon to post what we know on my web page and get of few of you doers
in the act.

Back to the gasifier for now....

Glad to hear {Tom Miles and Alex English}'s kind words.

Yours for now, TOM REED
BEF

In a message dated 7/22/99 9:00:28 PM Mountain Daylight Time,
tmiles@teleport.com writes:

<<
Alex,

I share your enthusiasm for the Turbo stove. When I visited Golden this
Spring Tom cooked part of our dinner on the stove. Very impressive and
needing to be widely used once it sees commercial daylight.

Prepared fuel is as important as ever but the concept works. We need to
explore its boundaries.

Regards,

Tom Miles

>>
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From elk at net2000ke.com Mon Jul 26 01:43:29 1999
From: elk at net2000ke.com (Elsen Karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Battery Turbo?
Message-ID: <199907260547.IAA20120@net2000ke.com>

Just back from a great vacation in Cape Town. Unlike many of the hard-core on the list, I didn't look at a stove with any design consideration once during this holiday........ and I'm not going to apologise!From the interesting messages awaiting me, I gather that Tom has finally unveiled his new stove- congratulations! I look forward to seeing drawings, photos and specifications.... hurry up Tom!What is the power source? I am still using my battery powered ceramic jiko (Fusion Stove?) and have brought back a new fan for it from Cape Town- a 12V DC squirrel cage fan. We'll see how well it functions in reverse, as it's supposed to suck, not blow.I'd be most interested in helping out on the Turbo Stove power-source in order to aim for an off-the-grid low power unit- wind-up (freeplay), solar, or just off the omni-present old car battery (re-charged weekly).Tell us more Tom.As for my Vendor's Waste Charcoal, I've commissioned another two extruders- that's five now, pushing production up to an average of 3000 kg/day. Getting serious!elk~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Elsen L. Karstad , P.O. Box 24371 Nairobi Kenyaelk@net2000ke.com tel/fax (+ 254 2) 884437

From heat-win at cwcom.net Tue Jul 27 12:51:27 1999
From: heat-win at cwcom.net (T J Stubbing)
Date: Tue Aug 31 21:36:21 2004
Subject: Need for a 1.2 million Btu/hour output wood, scrap charcoal and
Message-ID: <199907271651.MAA19325@solstice.crest.org>

pyrolysis gas burning stove
Content-Type: multipart/alternative;
boundary="------------B4EB99AF2F17142CE5C838D9"
Sender: owner-stoves@crest.org
Precedence: bulk

--------------B4EB99AF2F17142CE5C838D9
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Dear Stovers,

In a total of six hours we have (thus) dried logs and
converted them into
barbecue charcoal while emitting around 80% of the wood's
energy as
smoke! What we plan to do during the feasibility study is
ignite the
smoke and show that the combustion gases can not only operate
the
process but in addition dry around six times as much wood as
is
converted to charcoal so that both it and the extra dried wood
can be
sold.

Since then we have shown that with smaller section wood pieces and
relatively thin walled bamboo, combined with more rapid anaerobic
cooling the total process time can be reduced to three or four hours.

What we now need is a wood, charcoal scrap and/or pyrolysis gas burning
stove to replace the propane gas burner in the construction of a 1 ton
moist weight capacity machine.

To enable drying to be achieved in 1.5 to 2 hours I calculate that the
stove will need to burn the equivalent of 2.5 lbs/minute dry weight of
wood and have a thermal output of around 1.2 million Btu/hour.

Our aim is to be able to supply or licence others to manufacture and
supply machines independent of fossil fuels and able rapidly to produce
high net yields of both charcoal and various grades of better than kiln
dried firewood which, due to the rapidity of the process, will have a
low investment to output ratio.

At the moment we are held up by our lack of either the design of a stove
we could build ourselves or the name of a manufacturer of compact and
suitable wood burning stoves with 1.2 million Btu/hour outputs.

If you can help, please get in touch!

Regards,

Thomas J Stubbing

--------------B4EB99AF2F17142CE5C838D9
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit

Dear Stovers,

In a 2nd February message I posted under the heading "Clean Charcoaling" I
mentioned that, in an innovative propane gas heated 'airless', i.e.
superheated steam dryer/charcoal maker (see
<<http://www.dryers-airless.mcmail.com>http://www.dryers-airless.mcmail.<htt
p://www.dryers-airless.mcmail.com>com
> >:
>In a total of six hours we have (thus) dried logs and converted them into
>barbecue charcoal while emitting around 80% of the wood's energy as
>smoke! What we plan to do during the feasibility study is ignite the
>smoke and show that the combustion gases can not only operate the
>process but in addition dry around six times as much wood as is
>converted to charcoal so that both it and the extra dried wood can be
>sold.
>
>Since then we have shown that with smaller section wood pieces and
>relatively thin walled bamboo, combined with more rapid anaerobic cooling
>the total process time can be reduced to three or four hours.
>
>What we now need is a wood, charcoal scrap and/or pyrolysis gas burning
>stove to replace the propane gas burner in the construction of a 1 ton
>moist weight capacity machine.
>
>To enable drying to be achieved in 1.5 to 2 hours I calculate that the
>stove will need to burn the equivalent of 2.5 lbs/minute dry weight of
>wood and have a thermal output of around 1.2 million Btu/hour.
>
>Our aim is to be able to supply or licence others to manufacture and
>supply machines independent of fossil fuels and able rapidly to produce
>high net yields of both charcoal and various grades of better than kiln
>dried firewood which, due to the rapidity of the process, will have a low
>investment to output ratio.
>
>At the moment we are held up by our lack of either the design of a stove
>we could build ourselves or the name of a manufacturer of compact and
>suitable wood burning stoves with 1.2 million Btu/hour outputs.
>
>If you can help, please get in touch!
>
>Regards,
>
>Thomas J Stubbing
>--------------B4EB99AF2F17142CE5C838D9--

From larcon at sni.net Tue Jul 27 23:18:42 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Stubbing on stove need
Message-ID: <v01540b01b3c3e2cae8af@[204.131.233.38]>

Stovers: Tom Stubbing is asking for help on identifying a wood-burning
stove design in the range of 1.2 million Btu/hr (350 kW) (replacing a
propane burner). Tom's work seems to be quite novel for producing charcoal
efficiently from wet feed stock.

Tom: Since we haven't heard about your recent progress, could you give us
more detail on your success - maybe especially in igniting the pyrolysis
gases. Are you able to do this only after reaching a certain level of
dryness? etc.

Ron

>To: stoves@crest.org
>Subject: Need for a 1.2 million Btu/hour output wood, scrap charcoal and
>pyrolysis gas burning stove
>Dear Stovers,
>
>In a 2nd February message I posted under the heading "Clean Charcoaling"
>I mentioned that, in an innovative propane gas heated 'airless', i.e.
>superheated steam dryer/charcoal maker (see
><http://www.dryers-airless.mcmail.com>:
>
> In a total of six hours we have (thus) dried logs and converted them into
> barbecue charcoal while emitting around 80% of the wood's energy as
> smoke! What we plan to do during the feasibility study is ignite the
> smoke and show that the combustion gases can not only operate the
> process but in addition dry around six times as much wood as is
> converted to charcoal so that both it and the extra dried wood
> can be sold.
>
>Since then we have shown that with smaller section wood pieces and
>relatively thin walled bamboo, combined with more rapid anaerobic
>cooling the total process time can be reduced to three or four hours.
>
>What we now need is a wood, charcoal scrap and/or pyrolysis gas burning
>stove to replace the propane gas burner in the construction of a 1 ton
>moist weight capacity machine.
>
>To enable drying to be achieved in 1.5 to 2 hours I calculate that the
>stove will need to burn the equivalent of 2.5 lbs/minute dry weight of
>wood and have a thermal output of around 1.2 million Btu/hour.
>
>Our aim is to be able to supply or licence others to manufacture and
>supply machines independent of fossil fuels and able rapidly to produce
>high net yields of both charcoal and various grades of better than kiln
>dried firewood which, due to the rapidity of the process, will have a
>low investment to output ratio.
>
>At the moment we are held up by our lack of either the design of a stove
>we could build ourselves or the name of a manufacturer of compact and
>suitable wood burning stoves with 1.2 million Btu/hour outputs.
>
>If you can help, please get in touch!
>
>Regards,
>
>Thomas J Stubbing
heat-win@cwcom.net

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From elk at net2000ke.com Wed Jul 28 04:19:54 1999
From: elk at net2000ke.com (e. karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Sawdust Charcoal Briquettes
Message-ID: <v01510100b3c4931d0097@[195.202.65.141]>

Some typical crude boiling test results:

Charcoal type: Low pressure sun-dried screw extruded sawdust charcoal
briquette (cylindrical 2.5 cm dia. X 5 cm length) 25% clay binder plus 0.5%
stearic acid.

Stove type: 20 cm inner dia. ceramic lined 'improved charcoal jiko' using a
20 cm dia alu pot sitting 1.5 cm. above fuel.

Burn Duration: 2 hr. 45 min.

Water boiled: 1675 gms out of an initial 2000 gm starting at 14' C. (2000
m. altitude).

Ash content: 28%

Any comments? Comparisons? Rough efficiency calculations?

Input appreciated- as ever.

rgds;

elk

~~~~~~~~~~~~~~~~~~~~:
E.L. Karstad :
P.O. Box 24371 :
Nairobi, Kenya :
Fax/tel 884437 :
elk@net2000ke.com :
~~~~~~~~~~~~~~~~~~~~'

From Laxwjh at nottingham.ac.uk Wed Jul 28 08:04:53 1999
From: Laxwjh at nottingham.ac.uk (Warren Hicks)
Date: Tue Aug 31 21:36:21 2004
Subject: Development work/Lesotho
Message-ID: <13550070A1F@hermes.nottingham.ac.uk>

Hi Everyone,
I am a new subscriber to the service. My name is Warren Hicks and I
am a researcher at the University of Nottingham. I am currently
completing a Ph.D in solar cooling (Cooling, not cooking). However, I
am very interested in the use of solar energy for most applications.
Once I have completed my Ph.D I am going to Lesotho to work in the
appropriate technology section (ATS) for the Lesotho government.
Lesotho is one of the British protectorates in South Africa. My role
over there will be to provide engineering support to a number of
projects including fuel efficient/solar stoves and the development of
renewable energy sources. One of my principal roles will be to help
identify funding sources to establish and expand the projects
identified as key. To this end I would appreciate corresponding with
anyone who would be able to share their experiences and advice on the
introduction of solar cookers/renewable energy to developing
countries. Also any comments on who to approach for funding would be
valuable. Anyone with an interest in helping me and ATS to identify
fruitful directions for implementation of any forms of renewable
energy would be useful. Subjects that I would appreciate
corresponding on are solar cooking, heat driven engines for rural
electrification, microhydropower, solar drying and pasteurization and
wind power (particularly wind driven water pumps). I look forward to
corresponding with the group membership.
All the best
Warren Hicks
School of the Built Environment
Nottingham University University Park
Nottingham NG7 2RD
Tel: 0115 9513177 Fax: 0115 9513159 Above are UK
phone numbers for international calls replace the 0 with +44 E-mail:
laxwjh@hermes.nottingham.ac.uk
Warren Hicks
School of the Built Environment
Nottingham University
University Park
Nottingham
NG7 2RD
Tel: 0115 9513177
Fax: 0115 9513159
Above are UK phone numbers for international calls
replace the 0 with +44

E-mail: laxwjh@hermes.nottingham.ac.uk
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From larcon at sni.net Wed Jul 28 16:01:02 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Sawdust Charcoal Briquettes
Message-ID: <v01540b03b3c4db820d34@[204.131.233.48]>

Elsen - In order to answer your question on efficiency, we will need the
total starting weight of charcoal (or ending weight of ash). Or were you
just testing us on our ability to compute the interior volume of jikos and
the packing density you can achieve?

The key numbers needed are
1). the heat of vaporization of 1.675 kg water at 2.35 MJ/kg (3.94 MJ),
2) about .75 * 30 MJ/kg (= 22.5 MJ/kg) for the available energy in your
charcoal.
3) the energy needed to raise 2 kg of water from your 14 degrees to about
97 degrees (a guess) is 2000 g * 83 degrees * 1 cal/gm-degree * 4.186
Joules/cal =
0.7 MJ.

So to get 30% efficiency (or an output of .3 * 22.5 MJ/kg = 6.75 MJ/kg) for
the jiko, you would have needed to have started with an input charcoal
weight of

x (kg) = (0.7 MJ + 3.94 MJ) / (6.75 MJ/kg) = .69 kg

This ignores the value of having .325 kg of (purified?) hot (?) water left
at the end.

Your efficiency should be bigger or smaller than 30% by the ratio
of your weight to this weight

Now my questions - the 25% clay binder seems pretty large. Have
you tried customer satisfaction at various levels?
Does anyone think there is a better number than 30 MJ/kg for pure
charcoal?

Ron

>Some typical crude boiling test results:
>
>Charcoal type: Low pressure sun-dried screw extruded sawdust charcoal
>briquette (cylindrical 2.5 cm dia. X 5 cm length) 25% clay binder plus 0.5%
>stearic acid.
>
>Stove type: 20 cm inner dia. ceramic lined 'improved charcoal jiko' using a
>20 cm dia alu pot sitting 1.5 cm. above fuel.
>
>Burn Duration: 2 hr. 45 min.
>
>Water boiled: 1675 gms out of an initial 2000 gm starting at 14' C. (2000
>m. altitude).
>
>Ash content: 28%
>
>
>Any comments? Comparisons? Rough efficiency calculations?
>
>Input appreciated- as ever.
>
>rgds;
>
>
>elk
>
>
>~~~~~~~~~~~~~~~~~~~~:
>E.L. Karstad :
>P.O. Box 24371 :
>Nairobi, Kenya :
>Fax/tel 884437 :
>elk@net2000ke.com :
>~~~~~~~~~~~~~~~~~~~~'
>
>
>Stoves List SPONSORS and ARCHIVES:
>http://solstice.crest.org/renewables/stoves-list-archive/
>Stoves Webpage
>http://www.ikweb.com/enuff/public_html/Stoves.html
>For information about CHAMBERS STOVES
>http://www.ikweb.com/enuff/public_html/Chamber.htm

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From elk at net2000ke.com Thu Jul 29 01:54:36 1999
From: elk at net2000ke.com (Elsen Karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Sawdust Charcoal Briquettes
Message-ID: <199907290559.IAA12932@net2000ke.com>

From mheat at mha-net.org Thu Jul 29 05:51:49 1999
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:21 2004
Subject: Fwd: from strawbale list
Message-ID: <4.1.19990729045006.00ae3780@mha-net.org>

Hello everyone:

Thought I'd pass on the following article on wood chemistry, which was
reprinted today on the strawbale construction list.

Best........Norbert

>To: strawbale@crest.org
>From: Mark Piepkorn <duckchow@mail2.greenbuilder.com>
>Subject: OK, Brainiacs: Rot (extra credit)
>Sender: owner-strawbale@crest.org
>
>|------------------------------------------------|
>| Lignocellulose Composition (percentages) |
>|-----------|-----------|---------------|--------|
>| PLANTS | CELLULOSE | HEMICELLULOSE | LIGNIN |
>|-----------|-----------|---------------|--------|
>| Grasses | 25-40 | 25-50 | 10-30 |
>| Softwoods | 45-50 | 25-35 | 25-35 |
>| Hardwoods | 45-55 | 24-40 | 18-25 |
>|-----------|-----------|---------------|--------|
>
>This chart comes from issue sixteen of a way cool magazine called Science
>Spectra: The International Magazine of Contemporary Scientific Thought.
>("Winner of 1998 Folio Editorial Excellence Award.") Check out their
>website at http://www.gbhap.com/Science_Spectra/ for some excellent
>high-falutin' articles, including "The Globe as a Reaction Vessel:
>Environmental Chemistry With The Whole World As A Laboratory"... and "How
>They Explode: The Dynamics Of Volcanic Eruptions"... and "Sperms Galore:
>Why Mammals Produce Huge Numbers Of Spermatozoa." No kidding. You should
>subscribe today, and let that Reader's Digest and People Magazine stuff
>lapse. But not The Last Straw, OK? :)
>
>The article below is the one that the chart above came from. There's more
>charts, photographs, and illustrations that accompanied the article, but
>you'll have to get the magazine for 'em. It's worth it. Anyway, with the
>above chart in mind, anybody who can report back to the list about the
>ramifications of what it's saying with regard to strawbale - in plain
>English - gets extra credit.
>
> Seems to me that the news is good: that straw may be even more
>rot-resistant than some hardwoods. (Yes, I suppose that size does count.)
>
>*
>
>Completing the Carbon Cycle: HOW THE WOODY MATERIAL OF PLANTS IS DEGRADED
>by Chris F. Thurston
>
>The polymers that make up lignocellulose give strength to plant materials
>and are the dominant component of biomass on the land surface of this
>planet. Their very stability makes degradation difficult yet degraded they
>surely are or the whole of the Earth's land surface would be deep in the
>wood of history's plants. Chris Thurston of King's College London describes
>what we presently know about lignocellulose degradation.
>
>
>The bulk of nearly all land plants consists of leaf material and of the
>plants' structural support, varying from a slender wheat stem to the
>immense trunk of a noble forest tree. All these structures require
>mechanical strength and this is provided by lignocellulose, the main
>component of the cell walls of plant tissue and constituting 90 percent of
>the dry weight of the plant cell. So ubiquitous, lignocellulose is the
>principal form of fixed carbon in the terrestrial biosphere; we exploit its
>properties in everything we create employing wood. One of the reasons we
>are able do so is the very great resistance of wood to degradation,
>particularly if it is kept dry. This resistance depends upon the
>extraordinary complexity of woody materials and the array of enzymes
>required for their biodegradation.
>
>
>THE COMPONENTS OF LIGNOCELLULOSE
>
>Lignocellulose comprises three different polymer types: lignin,
>hemicellulose and cellulose. Indeed, its extraordinary properties result
>directly from its being a mixture of polymers with different physical and
>chemical properties. Cellulose at first sight appears to be a very
>uninteresting molecule. The simplest sort of polymer, it is made up only of
>glucose units in unbranched chains, each composed of thousands of sugar
>units with all the bonds between the glucose residues of the same sort.
>(Figure 1). This simplicity is deceptive: the regularity of the cellulose
>structure allows individual chains to align with others and constitute a
>microfibril so regular in its structure that it has crystal-like
>properties. The packing of cellulose chains into fibrillar structures
>(microfibrils are bundled into macroscopic fibers) not only gives woody
>materials their strength but also makes cellulose much more difficult to
>degrade than similar polymers that do not form ordered structures. The
>exact structure of cellulose is critical to its properties; if the
>orientation of the bonds between glucose residues is changed from B- (as in
>cellulose) to a- (as in amylose, a component of starch), the resulting
>polymer has much less tendency to form ordered structures and, indeed, is
>rapidly degraded by a single enzyme in our own saliva.
>
>Although traditionally called "hemicellulose," this second component of
>lignocellulose is misnamed. Hemicelluloses are mixtures of polymers made up
>of sugars (mostly not glucose) and sugar derivatives; the polymers may be
>branched and comprise different types of unit. A major component of
>lignocellulose in many types of plant (including trees, cereals and other
>grasses) is xylan. Figure 2 shows how xylan differs from cellulose: it has
>a backbone of five-carbon sugar units (many of them acetylated), with side
>chains of sugar derivatives and is highly charged by virtue of acidic
>groups (sugar acids). Other hemicelluloses contain other sugars but, like
>the xylans, are all unordered, branched and charged.
>
>Hemicelluloses provide a matrix in which cellulose fibers are embedded to
>form the layered structure of plant cell walls. The strength of
>lignocellulose depends on this matrix for its water-holding capacity
>because dehydrated cellulose fibrils have almost no mechanical strength.
>(On dehydration, wood shrinks dramatically and can be easily broken by
>hand. Remarkably, this loss of strength on dehydration is reversible - a
>property exploited in the timber industry where wood is dried in kilns to a
>suitable water content for use in construction, rather than having to wait
>for it to "season" as was done traditionally.) Hemicelluloses are always
>important components of plant cell walls and in some lignified tissues are
>the predominant material (Table 1).
>
>Lignin, the third component, is the Earth's most abundant aromatic polymer
>and the most unusual of the lignocellulose polymers (Figure 3). Cellulose
>chains, sometimes thousands of glucose residues long, are dwarfed by lignin
>which forms a molecular network in the plant cell wall such that the whole
>of the plant conceivably contains a continuously connected lignin molecule
>- look at a giant redwood, several hundred feet in length and weighing many
>tons, and you are looking at a single lignin molecule. How can such
>enormous and complex substances be broken down by agents as small as
>microorganisms?
>
>It is almost impossible to describe lignin structure in exact chemical
>terms because it has no stereochemical regularity. This results from the
>way it is assembled and has profound consequences for its degradation.
>Lignin is made up of units called lignols (Figure 4), each of which is an
>aryl propanol composed of an aromatic ring and a three-carbon chain. The
>lignols are structurally very closely related to the amino acids
>phenylalanine and tyrosine from which they are ultimately derived. Although
>lignin structure includes bonds between aryl propane units of great
>variety, for our purposes it is important to notice only that there are
>large numbers of carbon-carbon bonds and ether linkages, neither of which
>are easily susceptible to hydrolytic cleavage mechanisms. Special bonds
>link lignin to hemicelluloses (Figure 5).
>
>Lignin is more hydrophobic than the hemicelluloses and cellulose. It is
>likely that its structure, along with that of the hemicelluloses,
>contributes to the strength of the plant cell wall but this is probably not
>its main function. The distinctive and useful property of lignin is that it
>is so difficult to degrade; it therefore forms a protective layer
>preventing cell wall degradation by pathogens. The resistance of lignin and
>the crystal-like structure of cellulose fibrils are the two great problems
>to be overcome in the degradation of lignocellulose.
>
>
>BREAKING DOWN CELLULOSE
>
>Lignocellulose, or for that matter, pure cellulose (as produced by the
>cotton plant), are very large molecules and completely insoluble materials
>so the first step(s) in their degradation by environmental microbes must be
>extracellular. No microbial cell can absorb molecular complexes of the size
>of a cellulose fiber, still less that of lignin molecules. Lignocellulose
>breakdown is catalyzed by secreted enzymes which constitute a major
>fraction of the extracellular proteins in soil and compost systems.
>
>The enzymatic machinery for degrading cellulose, hemicellulose and lignin
>is possessed only by microorganisms. It is true that plants must contain
>enzymes for the occasional cleavage of their own cell wall materials to
>allow a whole range of structural changes during development, but neither
>higher plants nor animals can achieve the large-scale depolymerization of
>any of the lignocellulose polymers. Although animals do have a role in
>lignocellulose degradation in some environments, it is a mechanical one:
>ruminants and numerous soil earthworms and many arthropods chew up plant
>material into tiny fragments, greatly increasing the surface area available
>for attack and hence the rate of degradation by microbial enzymes.
>
>The environments in which ligno-cellulosic material can accumulate may be
>well aerated (aerobic) or essentially oxygen-free (anaerobic); both
>anaerobic and aerobic cellulose degraders have evolved. Clostridium
>thermocellum is an example of an anaerobic bacterial cellulose degrader.
>Originally isolated from compost, which becomes both anaerobic and very hot
>if not regularly mixed, this bacterium grows best at around 60C. Its
>complement of cellulolytic proteins illustrates most of the range of
>enzymatic activities that appear to be required in order to degrade cellulose:
>
>endo-B--1,4-glucanase which cleaves bonds apparently at random in a
>cellulose chain ("endo-" enzymes attack anywhere in the molecule, "exo-"
>enzymes only at the ends) - surprisingly, the organism has 15 separate
>genes for endogluconases;
>
>exoglucanases and cellobiohydrolases which cleave the terminal glucose and
>cellobiose (two glucoses at a time), respectively, from a chain, and can do
>so only from one end;
>
>B-glucosidase enzymes which cleave single glucose residues from small
>glucose polymers just a few units long.
>
>
>CONCERTED ACTION
>
>No one of these enzymes on its own is much good at breaking down undamaged
>cellulose fibers. They work in concert, which helps to explain why the C.
>thermocellum cellulolytic system is so elaborate. Held together by a
>scaffolding protein, this complex of catalytic activities (cellulosome) is
>ideally arranged to work cooperatively: it can be anchored to the substrate
>(the cellulose fiber) without the need for every component to have its own
>cellulose-binding domain. Because the cellulosome also binds to the C.
>thermocellum cell wall, the bacterium is anchored to the substrate in
>exactly the place where its nutrient is being solubilized. But this does
>not explain all the complexity - why are components of the
>hemicellulose-degrading machinery (xylanases) included and why are so many
>different endoglucanases involved (C. thermocellum makes 15!)?
>
>For aerobic bacteria like Cellulomonas fimi, there is presently no evidence
>for a cellulosome but the proteins are nevertheless surprisingly
>complicated. Multiple versions of some catalytic functions are present and
>many of the components are multi-domain proteins. While all have a
>cellulose-binding as well as a catalytic domain, some also embody other
>(apparently non-catalytic) domains of unknown function. A further point of
>interest is the presence of an enzyme hydrolyzing both cellulose and xylan,
>another hint that cellulose and hemicellulose degradation are closely
>integrated processes.
>
>The anaerobic fungi inhabiting the rumen of cows, sheep and other ruminants
>are the most recently discovered major group of cellulolytic microbes. They
>are amongst the most powerfully cellulolytic of all organisms; the enzymes
>they use have properties similar to the bacterial examples but are even
>more complicated. Some of these fungal cellulases have two or more
>catalytic domains, one an endocellulase and another a xylanase.
>Non-catalytic domains of several different types are found, including one
>for cellulose-binding, as well as xylan-binding domains and others of
>unknown function. The presence of cellulosomes is uncertain.
>
>These fungi share the rumen environment with many other microbes. As
>understanding of the structure of cellulolytic proteins has grown, it turns
>out that the cellulases of anaerobic fungi are more closely related to
>those of anaerobic bacteria than to those of aerobic fungi. This suggests
>that, as the rumen evolved, progenitors of the anaerobic fungi acquired
>cellulase genes from bacteria, an example of natural horizontal gene
>transfer which has probably often occurred during evolution in microbial
>communities.
>
>Many cellulolytic aerobic fungi are plant pathogens or symbionts that live
>cooperatively with their plant hosts. Their cellulose-degrading abilities
>are probably used not primarily for nutrition but to make holes in the
>plant cell wall as an aid to infection. By contrast, other fungi are
>devastating lignocellulose and cellulose degraders. Trichoderma reesei (one
>strain of which was originally isolated from the rotting canvas of a U.S.
>Army tent) has an extensively studied aerobic cellulolytic system.
>Biochemical analysis of the enzymes secreted by cellulolytic organisms is
>extremely complicated because
>
>* many enzymatically similar proteins can be produced;
>
>* they are often only produced in the presence of cellulose - to which they
>bind tightly - so they are difficult to detect and purify; and
>
>* the culture fluid in which they occur typically also contains proteases
>and glycosidases which can modify part of the cellulase molecules, making
>it appear that there are more proteins being produced than in fact are
>present.
>
>The cellulases of T. reesei include four endoglucanases, similar in
>catalytic activity to their bacterial counterparts, and two
>cellobiohydrolases. During growth on cellulose, two endoglucanases and the
>two cellobiohydrolases predominate. It is this mixture of enzymes (which
>can be dissociated from the cellulose by a biochemical trick) that is sold
>as a commercial product. If you have bought "stone washed" jeans in the
>last few years, they were almost certainly treated with T. reesei
>cellulases rather than being put in a washing machine with stones from the
>beach. The T. reesei cellulases all have a cellulose-binding domain so they
>are strongly bound to crystalline cellulose. There is evidence (but not yet
>certainty) that the cellulose-binding domain can help to disrupt the
>ordered structure of a cellulose microfibril, thus making a cellulose chain
>more accessible to the hydrolytic (chain-cleaving) activity of the enzyme.
>
>The favored explanation for this plethora of cellulases is that the enzymes
>together can more readily degrade the polymer than any individual enzyme
>can on its own. Thus, the rate at which crystalline cellulose is hydrolyzed
>by a mixture of a cellobiohydrolase and an endoglucanase would be expected
>to be greater than the sum of the rates of the two enzymes acting in
>separate reactions. This is indeed what happens, but strangely some
>mixtures of pairs of cellobiohydrolases or pairs of endoglucanases are also
>synergistic, which lacks obvious mechanistic explanation.
>
>
>BROWN ROT FUNGI
>
>T. reesei and its close relatives among the ascomycetes (the "soft rot
>fungi" - see box above) rapidly degrade pure cellulose and cellulose in
>plant tissue that is not heavily lignified but attack the cellulose in
>woody plant material poorly if at all. The "white rot" lignin-degrading
>fungi, as we shall shortly see, are often powerful cellulose degraders as
>well and employ more or less the same complement of enzymes as T. reesei.
>There is, however, another small but important group - the "brown rotters,"
>all basidiomycete fungi related to mushrooms, puff balls and brackets. The
>best known are the "cellar fungus" and Serpula lacrymans, the cause of dry
>rot of building timbers causing L 150 million of damage to buildings every
>year in the U.K. alone.
>
>These fungi are able to degrade the cellulose in wood without degrading
>lignin, although they may cleave or modify it here and there. The wood is
>converted to a dark brown fragile material with loss of strength occurring
>more quickly than loss of weight. The organisms secrete endoglucanases but
>whether they also secrete cellobiohydrolases is still obscure. In addition,
>cellobiose dehydrogenase is produced, a puzzling enzyme: because it
>catalyzes several different reactions, it is difficult to determine which
>ones are important in natural wood decay. One of the processes yields
>iron(II) and hydrogen peroxide, reactants which can form the hydroxyl
>radical HO*, which is the most reactive free radical species produced by
>biological systems and might explain the rapid fragmentation of cellulose
>fibrils by these fungi.
>
>
>HEMICELLULOSE DEGRADATION
>
>Like cellulose, the hemicelluloses, the smallest of the lignocellulose
>polymers, are amenable to hydrolytic cleavage; however, for the degradation
>of the whole range of hemicellulose structures, a complement of some 24
>enzymes is required. Most of them have now been described from at least one
>microbe but a full description of the complete complement, and of the genes
>encoding them, is not yet available for any single organism.
>
>Most is known about the enzymes degrading xylan, the endoxylanases and
>xylosidases. Hemicellulose degradation is a complex process because the
>enzymes are typically produced as multiple isoenzymes (enzymes with
>apparently the same specific catalytic function existing in more than one
>physical form that differ from each other in such properties as optimum
>pH); some have cellulose-binding domains, some are part of a multi-domain
>protein in which other domains degrade cellulose while, in some organisms,
>xylanase production is more strongly increased by the presence of cellulose
>than of xylan. The reasons for this variety are not understood.
>
>
>LIGNIN DEGRADATI0N
>
>The biological destruction of lignin requires oxygen. Thus lignin
>degradation simply does not occur in some natural environments. For
>example, in certain bogs, plant communities continually deposit dead
>material which, over many thousands of years, accumulates as peat because
>in waterlogged (and hence oxygen-depleted) acidic environments, lignin is
>not degraded. It is not known if less acidic anaerobic environments will
>allow lignin degradation but, in any event, it is very slow.
>
>Lignin is probably degraded by some bacteria although none of them has been
>isolated and grown in laboratory culture. Many filamentous bacteria
>(actinomycetes) can clearly modify lignin (this is a major feature of
>compost formation) but they cannot convert the bulk of lignin to carbon
>dioxide - that is, they cannot mineralize it. The only organisms shown to
>be able to mineralize a substantial fraction of lignin are all
>basidiomycetes - the white rot fungi. When they degrade wood or leaf
>litter, mineralization of the lignin component results in bleaching to a
>whiter color than undamaged wood - hence the name. Since degradation of
>lignin by white rotters is an oxidative process, scientists have long
>searched for oxidative ligninolytic enzymes.
>
>Such enzymes are of three types and not all white rot fungi use all of them
>to the same extent. Difficult to unravel, the process remains the least
>well understood major biochemical process. Remember that the natural
>substrate is an insoluble polymer of extraordinary complexity, mixed in its
>natural state with two other types of polymer, all making it very difficult
>to relate the natural process to laboratory studies. The three categories
>of enzyme are laccase, lignin peroxidase and manganese peroxidase.
>
>Laccase (see box on next page) has been known as a fungal product for over
>a hundred years but confusion about the nature of its substrates and mode
>of action led to a search for alternative enzymes to explain lignin
>breakdown. For the last 20 years, attention has focused on a fungus called
>Phanerochaete chrysosporium because it is a good wood degrader, grows
>rapidly and well in laboratory liquid culture and appears to produce no
>laccase. During the 1980s, two new enzymes were described from this fungus
>- lignin peroxidase and manganese peroxidase. They are remarkably similar
>in structure and both oxidize substrates at the expense of hydrogen
>peroxide reduction.
>
>These peroxidases, particularly the lignin peroxidase (the more strongly
>oxidizing of the two), can cleave a wide range of model compounds
>incorporating the types of bond found in lignin. They are good candidates
>for lignin degradation although it has been difficult to obtain conclusive
>proof in vitro. P. chrysosporium produces a great profusion of the enzymes
>- eight different lignin peroxidase and four different manganese peroxidase
>isoenzymes, some of them, in turn, encoded by a whole family of related
>genes. Such a multiplicity of genes and isoenzymes is for the moment
>entirely without explanation.
>
>The discovery of lignin peroxidase and manganese peroxidase was a turning
>point in understanding lignin breakdown, not only because enzymes were
>described which could cleave most if not all the bonds linking lignin
>units, but also because their properties, particularly those of manganese
>peroxidase, led to new ideas about lignin degradation. What was the point
>of an enzyme whose principal activity seemed to be that it could oxidize
>divalent [Mn(II)] to trivalent manganese [Mn(III)]? The answer appears to
>be that Mn(III) is a strong oxidizing agent which reacts with lignin
>leading to bond cleavage. Although the manganese ion is chelated to a small
>organic acid and somewhat stabilized, the oxidizing reagent is very small
>compared with an enzyme molecule and can diffuse into the lignin matrix,
>attacking bonds quite inaccessible to the active sites of the large
>proteinaceous lignin and manganese peroxidases. Thus, manganese peroxidase
>functions not by degrading lignin directly but by generating a diffusible
>mediating substrate. It is likely that similar mechanisms operate both for
>lignin peroxidase and laccase.
>
>The idea of mediating substrates has transformed our understanding of the
>contribution of laccases to lignin breakdown. With an appropriate mediating
>substrate, the enzyme can cleave the non-phenolic model dimers of lignin
>structure that were thought previously to be cleaved only by lignin
>peroxidase. In Pycnoporus cinnabarinus, a strongly ligninolytic fungus that
>produces abundant laccase but no lignin or manganese peroxidases, the
>mediating substrate for wood decay has been described. Very significantly,
>in an elegant assay based on keeping enzyme and lignin substrate separate
>by a dialysis membrane that allows only the mediating substrate to pass, it
>has been shown for the first time that lignin can be depolymerized by
>laccase in the test tube.
>
>
>THE DESTRUCTION OF WOOD
>
>The way a white rot fungus manages to integrate the degradation of lignin,
>cellulose and hemicellulose when degrading natural material is unknown.
>Just how the white rot fungi (and for that matter the brown rotters) avoid
>damage from the radical species they generate, and why some organisms
>produce such a profusion of ligninolytic isoenzymes, are issues that remain
>to be explored. These are important questions for the dynamics of the whole
>biosphere. Wood is not only the most stable of bioproducts; its sheer
>quantity is one of the major factors determining the shape and character of
>most natural environments. Furthermore, the lignin-degrading systems of
>white rotters are among the most effective biological systems for removing
>some of the worst organic pollutants devised by humans - the polyaromatic
>hydrocarbons and halogenated aromatics. But that is another story...
>
>
>SUGGESTED READING
>
>Glazer, A.N. and Nikaido, H. "Biomass," Microbial Biotechnology, 327-358,
>W.H. Freeman, New York (1995).
>
>Gold, M.H. and Alic, M. "Molecular biology of the lignin-degrading
>basidiomycete Phanerochaete chrysosporium," Microbiological Reviews 57,
>605-622 (1993).
>
>Kirk, T.K. and Farrell, R.L. "Enzymatic 'combustion': the microbial
>degradation of lignin," Annual Reviews of Microbiology 41, 465-505 (1987).
>
>- - - - - - - - -
>
>Chris F. Thurston, King's College London
>

----------------------------------------
Norbert Senf---------- mheat@mha-net.org-nospam (remove nospam)
Masonry Stove Builders
RR 5, Shawville------- www.mha-net.org/msb
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092

From elk at net2000ke.com Fri Jul 30 05:11:46 1999
From: elk at net2000ke.com (e. karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: In favour of Iron Pots
Message-ID: <v01510101b3c7408d960e@[195.202.65.88]>

Interesting snippet:

"Ethiopian children fed food from iron pots had lower rates of anaemia and
better growth than children whose food was cooked in aluminium pots.
Provision of iron cooking pots for households in less-developed countries
may be a useful method to prevent iron deficieancy anaemia"

Adish. A et al (1999): Effect of consumption of food cooked in iron pots on
iron status and growth of young children: a randomised trial. The Lancet,
Vol. 353, pp 712-716, Feb 27th 1999

~~~~~~~~~~~~~~~~~~~~:
E.L. Karstad :
P.O. Box 24371 :
Nairobi, Kenya :
Fax/tel 884437 :
elk@net2000ke.com :
~~~~~~~~~~~~~~~~~~~~'

From larcon at sni.net Fri Jul 30 13:34:02 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Forwarding Kiran Dhanapala request for assistance in Sri Lanka
Message-ID: <v01540b04b3c784b7923d@[204.131.233.9]>

Stovers: Kiran Dhanapala sent the following, which originally had as subject:
"Kirk Smith's work in India on health benefits from reduced indoor
air pollution from biomass stoves".

I am sure Kiran would welcome any other responses on IAQ.

Kiran: 1. Perhaps Kirk can forward a copy, or get in contact with you -
but I also suggest you look at the "stoves" webpage run by Alex English,
where there are still several papers by Kirk, I think.

Stoves Webpage: http://www.ikweb.com/enuff/public_html/Stoves.html

2. I am taking the liberty of signing you up for "stoves" (no
costs). Feel free to drop off whenever By way of further introduction,
would you please tell us more on what you are learning from your stoves
research in Sri Lanka?

(The remainder is from Kiran:)

I am a researcher based in Sri Lanka working on energy issues. I am currently
working on a short term research project on stoves work done in Sri Lanka.

I stumbled across your web page and some exchanges between stovers.
There is one reference to Kirk Smith's recent work on indoor air pollution in
India which I am having trouble tracking down. This refers to a paper
given by
him at a conference held by the Center for Science and Environment in Delhi in
July 1998. In this address there is a reference to valuation of the benefit in
reducing pollution exporsure (health benefits & extended life-years). Do you
know where I can access this paper or such information?

I would be very grateful for any leads you may be able to give me on tracking
this work down.

Many thanks and look forward to your response.

Best wishes,

Kiran Dhanapala

From larcon at sni.net Fri Jul 30 13:34:14 1999
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:21 2004
Subject: Stubbing on stove need
Message-ID: <v01540b05b3c7874b2d1e@[204.131.233.9]>

Tom: Thanks very much for a great recap on your efforts. Just a few
questions below

You said:

<snip>
>
>Coming back to charcoal making, last year I drafted a concept whereby
>moist wood
>could be efficiently and completely dried in this way and then, by raising the
>temperature in the airless dryer to that at which exothermal pyrolysis begins,
>converted to charcoal in the third of three sequentially operated chambers.
>
>Stovers know that up to around 80% of dry wood's energy is contained in
>the smoke
>generated during charcoal-producing pyrolysis and will realise that, if
>the smoke
>could be burnt to heat the airless, second chamber in the sequence, once
>pyrolysis
>had begun in the third chamber no other heat source would be needed to
>provide the
>heat input by both the second and first chambers.

Ron: The number 80% above sounds particularly high. Did this
refer to tradtional approaches or to yours? What sort of weight percentage
of charcoal are you achieving - on both a wet and dry input wood basis?
>
(You said:)
>It's because we want to burn all of the smoke and avoid any pollution that
>we plan
>always to duct it through the red hot embers of a wood burning stove.
>
(Ron:) 1. Our experience with smaller units certanly confirms the
need to start with relatively dry wood in order to flare the pyrolysis
gases. You probably answered this earlier, but could you explain why it is
not possible to let the wood dry naturally before charcoaling it?
2. The "ducting" of the pyrolysis gases through "red hot embers"
is not clear. Could you explain how this improves the ignitability.

(You said):
>This brings me back to the enquiry I posted yesterday for a dry wood, scrap
>charcoal and/or pyrolysis smoke burning stove to consume up to the
>equivalent of
>2.5 lbs/minute dry weight of wood and have a thermal output of around 350
>KW or 1.2
>million Btu/hour.
>
<snip>
>Regards,
>
>Thomas
>

(Ron:)
Maybe you should look at the recent work of Elsen Karstad on his
downdraft sawdust-charcoal convertor. I don't have the exact numbers, but
I am pretty sure he is operating well above 350 kW. Replacing sawdust with
wood should make the job even easier (less labor required). His design
could mean a second means of making charcoal (but from a dry source).

Again thanks you very much for a very complete response. Ron

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From tduke at igc.apc.org Fri Jul 30 15:26:31 1999
From: tduke at igc.apc.org (Thomas Duke)
Date: Tue Aug 31 21:36:21 2004
Subject: Iowa Renewable Energy Show Sept.
Message-ID: <37A1FC4F.81DF20E0@igc.apc.org>

Stovers,

The Iowa Renewable Energy Expo will take place in Cedar Rapids, Iowa,
September 23, 24, 25, and 26, 1999.

The format of the event will be workshops, public meetings, speakers,
and symposia at the Sheraton and Hawkeye Downs .

Contact:
Patti Cale
PO Box 725
Ankeny, IA 50021-0725
PH: 515.289.1999

Tom Duke

From heat-win at cwcom.net Sat Jul 31 01:59:24 1999
From: heat-win at cwcom.net (T J Stubbing)
Date: Tue Aug 31 21:36:21 2004
Subject: Stubbing on stove need
In-Reply-To: <v01540b05b3c7874b2d1e@[204.131.233.9]>
Message-ID: <37A299DC.264A0B83@cwcom.net>

Dear Ron and Stovers

Ronal W. Larson wrote:

> Tom: Thanks very much for a great recap on your efforts. Just a few
> questions below
>
> You said:
>
> <snip>
> >
> >Coming back to charcoal making, last year I drafted a concept whereby
> >moist wood
> >could be efficiently and completely dried in this way and then, by raising the
> >temperature in the airless dryer to that at which exothermal pyrolysis begins,
> >converted to charcoal in the third of three sequentially operated chambers.
> >
> >Stovers know that up to around 80% of dry wood's energy is contained in
> >the smoke
> >generated during charcoal-producing pyrolysis and will realise that, if
> >the smoke
> >could be burnt to heat the airless, second chamber in the sequence, once
> >pyrolysis
> >had begun in the third chamber no other heat source would be needed to
> >provide the
> >heat input by both the second and first chambers.
>
> Ron: The number 80% above sounds particularly high. Did this
> refer to tradtional approaches or to yours? What sort of weight percentage
> of charcoal are you achieving - on both a wet and dry input wood basis?

Thomas: In a recent test we began with 69 kg of 90-130 mm long and 25-60 mm thick
pieces of sycamore with a probe-metered 25-31% moisture content range which
finished up as 20 kg of lump
charcoal. The yield was therefore 28% wet basis or around 40% dry basis.

At 185 minutes when the indirect heater was turned off and cooling began the
'off-heater' temperature was 323 C, 'off-charcoal' 317 C, centre of small piece 340
C and centre of largest piece 118C, as recorded by thermocouples.

When the stillage was removed after cool-down at 235 minutes the temperatures were
140, 150, 160 and 157 C respectively.

Analysis of an average piece gave a calorific value of 27,110 kJ/kg which
translates to (27,110 ~ 2.205 ~ 1.055) = 11,654 Btu/lb. Unfortunately the analysis
doesn't show the fixed carbon percentage, but gave moisture as 4.1%, ash 3%,
volatile matter 33.4% and sulphur 0.1%.

The thickness range led to the largest piece only getting up to the final 157 C
maximum, which isn't high enough for complete carbonisation of that and a few other
large pieces, my conclusion being that we should have let the load dwell from 185
to, say, 200 minutes in the 323 C 'off-heater' 'smoke' recirculation before
commencing the cool-down.

As you can see, our efforts are still amateur!

> Ron: (You said:)
> >It's because we want to burn all of the smoke and avoid any pollution that
> >we plan
> >always to duct it through the red hot embers of a wood burning stove.
> >
> (Ron:) 1. Our experience with smaller units certanly confirms the
> need to start with relatively dry wood in order to flare the pyrolysis
> gases. You probably answered this earlier, but could you explain why it is
> not possible to let the wood dry naturally before charcoaling it?

Thomas: The sycamore had been dried naturally down to 25 - 31%. Drying it
completely before pyrolysing it prevents steam at 1.67 m3/kg or 27 ft3/lb of
moisture removed during pyrolysis diluting the pyrolysis gases, making them harder
to ignite and giving a lower combustion gas temperature, while during the drying
phase drying the energy in the vented steam can be recovered for re-use by
condensing it in a condenser to produce a flow of 95 C+ process water or air.

> Ron: 2. The "ducting" of the pyrolysis gases through "red hot embers"
> is not clear. Could you explain how this improves the ignitability.

Thomas: "Red hot embers" in a 900 C+ stove interior simply provide an efficient
ongoing igniter while enabling the energy produced by burning the pyrolysis gases
to substitute for some of the wood which would otherwise be burnt.

> Ron: (You said):
> >This brings me back to the enquiry I posted yesterday for a dry wood, scrap
> >charcoal and/or pyrolysis smoke burning stove to consume up to the
> >equivalent of
> >2.5 lbs/minute dry weight of wood and have a thermal output of around 350
> >KW or 1.2
> >million Btu/hour.
> >
> <snip>
> >Regards,
> >
> >Thomas
> >
>
> (Ron:)
> Maybe you should look at the recent work of Elsen Karstad on his
> downdraft sawdust-charcoal convertor. I don't have the exact numbers, but
> I am pretty sure he is operating well above 350 kW. Replacing sawdust with
> wood should make the job even easier (less labor required). His design
> could mean a second means of making charcoal (but from a dry source).

Thomas: Thank you, I will! However, we want to make charcoal by indirect rather
than direct heating, so would use Elsen's converter to combust all of its sawdust
or wood input to turn them into the combustion gases needed by our machine's
indirect heater.

If Elsen reads this, can he please send me info. on his converter?

> Again thanks you very much for a very complete response. Ron
>
> Ronal W. Larson, PhD
> 21547 Mountsfield Dr.
> Golden, CO 80401, USA
> 303/526-9629; FAX same with warning
> larcon@sni.net
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm

From elk at net2000ke.com Sat Jul 31 03:21:54 1999
From: elk at net2000ke.com (Elsen Karstad)
Date: Tue Aug 31 21:36:21 2004
Subject: Stubbing on stove need- Sawdust Pyrolysis
Message-ID: <199907310726.KAA02617@net2000ke.com>

Thomas;I do not have a package of info at hand, but all my work is laid out in reasonable detail in the 'Stoves' archives. I don't think that a photo of my most recent sawdust carboniser is posted on the website- I'll update & send a pic. to Alex. Contact me directly if you have problems with the archives & I'll root through my computor & try to find those specific contributions.There may be an application here for you- particularly if you can use the carbonised sawdust that my system produces. Going by standard figures in the pyrolysis of air-dry sawdust at a 25% conversion by weight, I have been led to believe that 60% of the initial sawdust's energy is flared. This could provide heat for any application, providing flue draught is not seriously reduced.rgds;elk~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Elsen L. Karstad , P.O. Box 24371 Nairobi Kenyaelk@net2000ke.com tel/fax (+ 254 2) 884437

From Alex.English at adan.kingston.net Sat Jul 31 20:54:04 1999
From: Alex.English at adan.kingston.net (*.english)
Date: Tue Aug 31 21:36:21 2004
Subject: Turbo Stove Information
Message-ID: <199908010056.UAA29922@adan.kingston.net>

Dear Stovers,
There are now two papers about the Turbo stove posted under the
"New" heading on the Stoves Webpage.

Alex
Alex English
RR 2 Odessa, Ontario, Canada
K0H2H0 613-386-1927
Fax 613-386-1211
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http://www.ikweb.com/enuff/public_html/Chamber.htm

BioEnergy Lists: Improved Biomass Cooking Stoves

July 1999 Biomass Cooking Stoves Archive