September 2001 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 psanders at ilstu.edu Sun Sep 2 14:04:10 2001
From: psanders at ilstu.edu (Paul S. Anderson)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
Message-ID: <4.3.1.2.20010902130552.01a29580@mail.ilstu.edu>

Briquettes with holes

Dear Stovers and Friends,

My goodness, we all have been quiet for the past weeks.

Here is a summary of my current efforts and thoughts:

One issue is the holes in the briquettes. I wanted to test having
multiple (3 or 4) holes in the standard briquettes advocated by Richard
Stanley and the Legacy Foundation, of which I am a believer and
advocate.

I took an existing 4 inch (10 cm) diameter (and about 5 inches 13 cm
high) recycled biomass briquette that had one hole. I plugged the
center hole (not very well, but sufficient) with the same materials that
I cut out of the briquette when I DRILLED three holes down through the
diameter-side. The drill bit said
5/8th
inch (about 1.5 cm), being slightly smaller than the standard center-hole
in Richard’s briquettes.

After some “playing around”, I wrapped the briquette fairly tightly in a
piece of thin sheet metal (easily cut with tin-snips), tied it with a
discarded wire coat hanger, and thereby created a cylinder about 8 inches
(20 cm) high. [Therefore, there was some chimney effect.]
Plenty of air was available through the bar-b-q grill under the
cylinder.

Wow, did it burn well!! All three holes were shooting flames.
No detectable smoke (the “eyes and nose” test). Sorry, no
photograph yet available. But it looks like Richard’s pictures of
flames from a central hole, but this time with 3 holes blazing
away.

Second: That lowly test (plus my limited experiences making and
burning briquettes in my backyard and in Mozambique) leads me to the
following items, each of which needs additional research:

1. There is a wealth of heat-generating benefits from having
different numbers of holes in the briquettes.

2. They can be made easily using the same technology as the
single-hole ones. (Ed Francis and I are working on making the
piston / press-plunger for multiple holes.) Note:
We can use the same 4-inch (inside diameter PVC pipe) for the
cylinder.

3. The stove needs to snuggly hold the briquette (to minimize the
outside burning, where temperatures are lower and combustion is less
efficient/effective).

4. The 4-inch (10 cm) diameter is possibly too SMALL. I want
to experiment with briquettes that would just fit into a standard “number
10 tin” (which is American talk for a metal can about 7 inches (18
cm) in diameter and about 8 inches (20 cm) high.

5. Technically, there is no requirement that the briquette is
round. Square ones could fit together better in a larger
stove. Although this is a relatively minor issue at
present, I believe that commercially produced (home industry) large
briquettes might give some significant advantages when placed in “better”
(probably larger and more costly) stoves with special characteristics
such as are mentioned in the next item.

6. A stove (even a small one for a standard-size briquette) could
be made in which the briquette with a “standardized” hole configuration
would rest on a base plate that has the desired number of properly spaced
2 or 3 cm holes (for air) in the plate. Those holes could be easily
closed (use “plugs” or stoppers or sliders of metal?) or opened so that
burning could be somewhat controlled. For example, ignite 4 holes
but later shift back to only 2 or one, or almost none as in the
“slow-combustion stoves” that I know of from Brazil and Australia.

7. Couple all of this with the varieties of briquette materials (I
am thinking of the 40% charcoal “dust” briquettes we are making in
Mozambique for experiments) and you could have some major “user-control”
of the types of fires available.

So, I will continue to have fun with the briquettes project. Your
comments will be carefully studied. We need LOTS of help and
further experimentation of all types in different settings.

And to Ron L and others: Does anything said above make enough sense
to get included into someone’s grant proposal for Shell Foundation or
other sources? IF yes, please let me know. I would be very
interested in being part of a team effort.

I am SOOOOOO sorry that I will not be attending the biomass conference in
September in Orlando. I would learn a lot and meet many of
you. But I am just an amateur and a true beginner with this stoves
stuff.

Having fun !!

Paul

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 -
7/00
Dept of Geography - Geology (Box 4400), Illinois State
University
Normal, IL 61790-4400 Voice:
309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items:
www.ilstu.edu/~psanders

From ronallarson at qwest.net Sun Sep 2 22:10:36 2001
From: ronallarson at qwest.net (Ron Larson)
Date: Tue Aug 31 21:37:00 2004
Subject: Help me with a Question--PLEASE (on charcoal combustors)
In-Reply-To: <5367-3B929267-435@storefull-213.iap.bryant.webtv.net>
Message-ID: <01bc01c1341d$3a962960$a1b16441@computer>

"Nay" (Nadine)

I am sending this on to the full "stoves" list, as this raises some
interesting questions: Please see the tentative answers below. I hope
other stovers will join in.

----- Original Message -----
From: "nay" <NB-1@webtv.net>
To: <larcon@sni.net>
Cc: <nb-1@webtv.net>
Sent: Sunday, September 02, 2001 2:11 PM
Subject: Help me with a Question--PLEASE

>
> I recently stumbled on a very old
> Better Homes& Gardens cook book
> the particular article that caught my attention says as follows.....
>
(RWL): Could you give us the date of the book and page numbers of this
article - as I like most of the instructions and it might be fun to see the
original, if we can fnd it.

> ""You can make a whole group of multi-size
> grills from clay flowerpots and saucers.

(RWL): Clay is an excellent material for "grills". The only down side
is not being as tough as metal - and so probably won't last as long. They
should be easily able to handle the temperature involved - but it would be
best to try to heat evenly. The saucer is probably not too necessary - but
offers no harm,

> Line pots to brim with foil; fill 2/3 full of (mica-like insulating
> pellets--or use sand or gravel topped with a square of foil.

(RWL): The reason for the (aluminum) foil is that it is a good heat
reflector. Putting a layer on the outside of the flowerpot will also reduce
radiative losses even further.

The "mica-like insulating pellets" (maybe the word "vermiculite" was
here) is a non-flamable, relatively high temperature lightweight insulating
material. I have not seen vermiculite "pellets" - but rather we see small
expanded very light weigth pieces about as big as a large grain of wheat.

I don't like the idea of sand as much - as it will absorb and
/conduct/transmit a lot more heat. Gravel should be less dense and better -
even allowing some air flow upward. Best might be a real lightweight "lava
material". In the absence of other things, dirt will work pretty well.

The idea of filling 2/3 high is probably a compromise - of getting
enough sand (?) in weight in place for stability - and leaving some room
above for obtaining a uniform heat distribution for the hamburgers, hotdogs,
roasts, chickens (getting pretty large for only 6-8 briquettes).

The "square of foil" is again to reflect heat upwards. Several layers
with vermiculite between will be an even better lower insulator.

One part of this description I don't like is that there is no mention of
air flow from below. Air will definitely get to the lighted charcoal pillow
briquettes by spilling over the top of the flower pot - but maybe not as
much as you would like. And if you have a lot of vermiculite or sand, there
will not be much coming up from the bottom. If one could put small holes or
slits in the flower pot sides or one larger hole with a grate below, your
flower pot would look a lot more like the "jikos" that we see developed for
charcoal burning. (Jikos are often advertised as being best with 19 holes
(rings of 6 and 12 around a central hole.)

>Add 6--8
> charcoal briquets, lighter fluid, and set aflame.

(RWL): The person on our list who has done the most R&D with charcoal
combustion is Paul Hait - President of a firm called Pyromid. Hopefully
Paul can chime in with some ideas for small scale testing of air flow. Paul
sells units of different sizes made of stainless steel (good reflector,
relatively poor on heat conduction), that are carefully designed to reflect
a majority of heat upward. He never piles briquettes on each other, but
rather places them on edge facing each other in what he terms a "harmonic
array". This way the energy radiated sideways is largely captured by a
neighbor and works to keep each briquette hot - which you want. His bottom
plate has slits to hold the briquettes and other holes to supply air between
the briquettes. Because of his patents, you can't make and sell something
similar, but I would suggest his basic concepts of fuel placement and
careful use of reflectors and air holes are worth observing. I don't
remember his statements about fuel savings but they are considerable.
Again, just try to redirect all energy upwards

There are some places that discourage or prohibit the use of lighter
fluids - as they are a major cause of ozone production. Try surrounding the
charcoal with a "tall" cylinder of metal or ceramics and the added "chimney
draft" will help a lot to cut down on the starter fluid. Also try putting
some vaseline on a few cotton swabs. Much safer.

>Cover top with wire
> mesh or cake rack"

(RWL): Generally jikos I have seen have the cookpot sitting right on the
charcoal - but the normal American backyard cooker needs something to put
the meat (or potatoes, etc) on. The author is mentioning wire mesh as this
is presumably supposed to be a low cost approach.

> ( IS THAT POSSIBLE ---- I DONT WANT TO BLOW UP NEW YORK )
>
(RWL): Nothing much can go wrong here. The only thing worth worrying
about is that I would avoid cooking indoors. This list has heard a lot
about charcoal producing carbon monoxide - an odorless lethal gas.

> What puzzles me is:
> What is Insulating mica--like pellets & where could I purchase such a
> product?.
>
(RWL): Bags can usually be found in garden shops - to be used to help
aerate soil. I would recommend lightweight "lava" as well.

>
> I did a search VIA internet ---That's how I came across this web-site.
>
>
"""http://solstice.crest.org/renewables/stoves-list-archive/msg01201.html"""
>
> any Info that you submit would be gratefully appreciated.
>
> Thank You Kindly
> .................Nadine---NY
>

Nadine - I'm glad you found us. Surprisingly, in over five years now
we have not really had this same question. This list mostly exists to try
to
improve the efficiency and health safety of simple wood and charcoal
stoves - but we have done very little along this line of reporting
experiments with simple home-made charcoal cookers. As you wrote to me
off-list, I hope you will maybe join us as a (free) list member, but at
least report back on what you learn as you experiment. Keep looking into
the "stoves" list archives as others may join in.

As I have some flower pots around, I think I will try some experiments -
especially on this issue of air supply.

Stovers? More to say? Anyone know how to make the perfect jiko? Anyone
know of comparative amounts of CO with different designs?

Ron

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

Sponsor the Stoves List: http://www.crest.org/discuss3.html
-
Other Biomass Stoves Events and Information:
http://www.fsec.ucf.edu/bioam/
http://solstice.crest.org/renewables/biomass-info/
http://solstice.crest.org/renewables/biomass-info/carbon.shtml

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From ronallarson at qwest.net Sun Sep 2 22:11:20 2001
From: ronallarson at qwest.net (Ron Larson)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
In-Reply-To: <4.3.1.2.20010902130552.01a29580@mail.ilstu.edu>
Message-ID: <01bb01c1341d$34771580$a1b16441@computer>

Hi Paul -

Thanks for your report.
See some notes and questions below.
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Paul S.
Anderson
To: <A
href="mailto:ajmalawene01@hotmail.com"
title=ajmalawene01@hotmail.com>Apolinário J Malawene ; <A
href="mailto:bobkarlaweldon@cs.com" title=bobkarlaweldon@cs.com>Bob and Karla
Weldon ; Ed
Francis ; <A href="mailto:rstanley@legacyfound.org"
title=rstanley@legacyfound.org>Richard Stanley ; <A
href="mailto:rwalt@gocpc.com" title=rwalt@gocpc.com>Robb Walt ; <A
href="mailto:stoves@crest.org" title=stoves@crest.org>stoves@crest.org ;
<A href="mailto:TOMBREED@HOME.COM"
title=TOMBREED@HOME.COM>TOMBREED@HOME.COM ; <A
href="mailto:ajtsamba@zebra.uem.mz"
title=ajtsamba@zebra.uem.mz>Tsamba--Alberto Julio ; <A
href="mailto:clucas33@yahoo.com"
title=clucas33@yahoo.com>clucas33@yahoo.com ; <A
href="mailto:clucas@zebra.uem.mz"
title=clucas@zebra.uem.mz>clucas@zebra.uem.mz
Sent: Sunday, September 02, 2001 12:07
PM
Subject: Briquettes with holes

Briquettes with holesDear Stovers
and Friends,My goodness, we all have been quiet for the past
weeks.Here is a summary of my current efforts and thoughts:One
issue is the holes in the briquettes. I wanted to test having multiple
(3 or 4) holes in the standard briquettes advocated by Richard Stanley and the
Legacy Foundation, of which I am a believer and advocate.I took an
existing 4 inch (10 cm) diameter (and about 5 inches 13 cm high) recycled
biomass briquette that had one hole. I plugged the center hole (not very
well, but sufficient) with the same materials that I cut out of the briquette
when I DRILLED three holes down through the diameter-side. The drill bit
said 5/8th inch (about 1.5 cm), being slightly smaller than the
standard center-hole in Richard’s briquettes.
After some “playing around”, I wrapped
the briquette fairly tightly in a piece of thin sheet metal (easily cut with
tin-snips), tied it with a discarded wire coat hanger, and thereby created a
cylinder about 8 inches (20 cm) high. [Therefore, there was some chimney
effect.] Plenty of air was available through the bar-b-q grill under the
cylinder.Wow, did it burn well!! All three holes were shooting
flames. No detectable smoke (the “eyes and nose” test). Sorry, no
photograph yet available. But it looks like Richard’s pictures of flames
from a central hole, but this time with 3 holes blazing away.

(RWL): Q1a. Could you tell us a
bit about your lighting - from the top or bottom?
(Either?)

Q1b.
Easier now to light - with the wrap around "chimney"?

Q1c. What happened
after the briquette had pyrolyzed? Was there a distinct change in power
output? Would it be feasible to stop the action - or instead increase
air flow?
Second: That lowly test (plus
my limited experiences making and burning briquettes in my backyard and in
Mozambique) leads me to the following items, each of which needs additional
research:1. There is a wealth of heat-generating benefits from
having different numbers of holes in the briquettes.2. They can
be made easily using the same technology as the single-hole ones. (Ed
Francis and I are working on making the piston / press-plunger for multiple
holes.) Note: We can use the same 4-inch (inside
diameter PVC pipe) for the cylinder.3. The stove needs to
snuggly hold the briquette (to minimize the outside burning, where
temperatures are lower and combustion is less
efficient/effective).

(RWL): I'd
like to see a test where the fit was not so snug. I believe there might
be very little (or no) combustion on the outside. A little extra
air on the outside might provide cleaner burning (especially late in the
process). How much above the 8" metal cylinder did the flames appear (at
first, at maximum, and at the end)? Now we are talking about the
emissions from the flame - do you have any access to any emissions monitoring
equipment? 4. The 4-inch (10 cm) diameter is possibly too
SMALL. I want to experiment with briquettes that would just fit into a
standard “number 10 tin” (which is American talk for a metal can about 7
inches (18 cm) in diameter and about 8 inches (20 cm) high.
(RWL): This
may be a bit wider than needed for the test described above - but it certainly
sounds like another good test. I would also like to see tests of
briquettes (and chimneys) of different heights. Also replacing the metal
surrounding with ceramics is probably a worthwhile.test to increase
efficiency.
5. Technically, there is no
requirement that the briquette is round. Square ones could fit
together better in a larger stove. Although this is a
relatively minor issue at present, I believe that commercially produced (home
industry) large briquettes might give some significant advantages when placed
in “better” (probably larger and more costly) stoves with special
characteristics such as are mentioned in the next item.6. A
stove (even a small one for a standard-size briquette) could be made in which
the briquette with a “standardized” hole configuration would rest on a base
plate that has the desired number of properly spaced 2 or 3 cm holes (for air)
in the plate. Those holes could be easily closed (use “plugs” or
stoppers or sliders of metal?) or opened so that burning could be somewhat
controlled. For example, ignite 4 holes but later shift back to only 2
or one, or almost none as in the “slow-combustion stoves” that I know of from
Brazil and Australia.

(RWL): All good ideas. Rotation of one set of holes
past another similar set is another possibility.
7. Couple all of this with the
varieties of briquette materials (I am thinking of the 40% charcoal “dust”
briquettes we are making in Mozambique for experiments) and you could have
some major “user-control” of the types of fires available.

(RWL): Agreed
- I hope you will keep in mind the possibility of producing charcoal at
the same time. I am concerned you may not be getting very good
combustion in the late stages.So, I will continue to have fun with the
briquettes project. Your comments will be carefully studied.
We need LOTS of help and further experimentation of all types in different
settings.
(RWL): Any
chance of shipping some of these to others?
And to Ron L and others: Does
anything said above make enough sense to get included into someone’s grant
proposal for Shell Foundation or other sources? IF yes, please let me
know. I would be very interested in being part of a team
effort.
(RWL): I
still like everything I hear about holes in briquettes. If the idea is
indeed new and you can prove especially something about lowered emissions, I
presume that the Shell Foundation would find a proposal to be of value.
Your discussion above talks also about controllability, which is a major
plus. You and Richard Stanley would seem to have a lead in this type of
research. Because you have given this suggestion to several hundred
"stoves" list members - maybe they will also be writing you. Hard to say
which is the best way for those of you who have been promoting "holey"
briquettes - and it depends a lot on what you want to do. Your
expression of interest is presumably a good first step to finding
partners. If you don't hear, you presumably have to send in a proposal
yourself.

The Shell Foundation meeting
is on October 11-13, with a report coming out some time thereafter - possibly
with a number of different requests for proposals. I guess it will be
hard to ask for proposals to be received sooner than December - probably
later. I think about at least 10 of that group will be reading your
notes - and would like to hear your recommendations (as well as from anyone
else on the "stoves" list).
I am SOOOOOO sorry that I will not be
attending the biomass conference in September in Orlando. I would learn
a lot and meet many of you. But I am just an amateur and a true beginner
with this stoves stuff.Having fun !!Paul (RWL): Glad to
receive your reports and that you are having fun..

I have just started reading a
doctoral thesis on pyrolysis (both modeling and experiments) and will send a
report on it soon - that I think will give some other good insights on the
processes you have been investigating. For instance, surface temperature
is clearly an important property - and shows why an interior hole is so much
better than an exterior wall.

We are mostly amateurs.
If there were lots of real expertise around (and if the rural stove
problem was an easy one), we would have already heard a lot about "holey"
briquettes and lots of other "perfect" stove topics. I believe what you
are doing will prove to be a very good lead on making better stoves.
Hope you can keep it up.

Best of luck and again thanks
for an important report.

Ron

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 -
7/00
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360;
FAX: 309-438-5310E-mail: psanders@ilstu.edu - Internet items: <A
href="http://www.ilstu.edu/~psanders"
EUDORA="AUTOURL">www.ilstu.edu/~psanders

From tombreed at home.com Tue Sep 4 11:44:34 2001
From: tombreed at home.com (Thomas Reed)
Date: Tue Aug 31 21:37:00 2004
Subject: GAS-L: Re: Briquettes with holes
In-Reply-To: <31ee72c98d.2c98d31ee7@pmel.noaa.gov>
Message-ID: <017b01c13485$44e77a00$18e5b618@lakwod3.co.home.com>

Dear Tami:

VERY interesting comments on the coal briquettes from China.

1) Above a few hundred C, radiation is the principal heat transfer
mechanism for pyrolysis/combustion. Every Boy Scout knows you need three
logs (to form a radiation cavity) to start a fire. There is also a sawdust
burner with a hole in the middle that sometimes works.

The holes in your briquettes then provide a radiation trap to keep the heat
in the combustion zone.

A similar principle (radiation trap) explains the extraordinarily high heat
transfer in downdraft gasifiers, the holes being the interstices between the
particles where tar combustion occurs.

2) Ice cubes and black powder often have holes in the middle. As a cube
melts it gets smaller, so there is less surface exposed and less cooling of
the drink. If there is a hole in the middle the inside surface expands, so
total surface is approximately constant. Same principle for explosives to
propel shells from a cannon. MAYBE similar principle in holy briquettes.
Paul Anderson has been pioneering holey biomass briquettes in Mozambique
here recently. Comments?

Yours truly, TOM REED
Dr. Thomas Reed
The Biomass Energy Foundation
1810 Smith Rd., Golden, CO 80401
303 278 0558;
tombreed@home.com; www.woodgas.com
----- Original Message -----
From: "Tami Bond" <Tami.Bond@noaa.gov>
To: <stoves@crest.org>
Sent: Monday, September 03, 2001 6:12 AM
Subject: Re: Briquettes with holes

> Dear Stovers,
>
> Hi, I'm Tami Bond, a quiet member of this list for some time now. I do
> emissions testing when I can drag myself away from my other projects,
> and from listening to stove-talk. I'm new, and learning.
>
> I have watched the discussion on holey briquettes. While I have no
> experience with the biomass briquettes, I have tested the holey
> honeycombs (Coal) that are used in China. Pretty darn good in terms of
> particulate emissions. They do make really small particles (<50 nm, you
> can't see 'em) but the magnitude is much smaller than that from raw
> coal-- like two orders of magnitude fewer particles.
>
> From my observation the combustion is stabilized by the radiant
> feedback within the hole. The honeycomb briquettes are fairly dense,
> with low volatile content (and very hard to light). Keeping combustion
> going requires maintaining sufficient heat for reaction. This is a
> competition between the heat generated by oxidation and heat drawn away
> by conduction into the briquette. Up to a point, I would guess that
> with more holes, (a) more heat is generated, (b) the briquette is
> warmer inside, (c) the heat transfer from the surface to the interior
> of the briquette is lower, since heat transfer is proportional to the
> temperature difference. So more heat stays at the surface to maintain
> reaction. Even after my briquettes are burning well there is not much
> combustion around the outside.
>
> It is hard to stop these coal briquettes from burning once you have
> started them. This would be a disadvantage to making a larger
> briquette. I have heard that in China, people just cover the stove
> inlet to slow the combustion down. The homeowners tend to use about 4"
> briquettes and the larger ones I have tested (6") are used by street
> vendors. The biomass briquettes may perform entirely differently.
>
> Sincerely yours,
>
> Tami
>
>
> -
> Stoves List Archives and Website:
> http://www.crest.org/discussion/stoves/current/
> http://www.ikweb.com/enuff/public_html/Stoves.html
>
> Stoves List Moderators:
> Ron Larson, ronallarson@qwest.net
> Alex English, english@adan.kingston.net
> Elsen L. Karstad, elk@wananchi.com www.chardust.com
>
> List-Post: <mailto:bioenergy@crest.org>
> List-Help: <mailto:bioenergy-help@crest.org>
> List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
> List-Subscribe: <mailto:bioenergy-subscribe@crest.org>
>
> Sponsor the Stoves List: http://www.crest.org/discuss3.html
> -
> Other Biomass Stoves Events and Information:
> http://www.fsec.ucf.edu/bioam/
> http://solstice.crest.org/renewables/biomass-info/
> http://solstice.crest.org/renewables/biomass-info/carbon.shtml
>
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>

-
Gasification List Archives:
http://www.crest.org/discussion/gasification/current/

Gasification List Moderator:
Tom Reed, Biomass Energy Foundation, Reedtb2@cs.com
www.webpan.com/BEF
List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

Sponsor the Gasification List: http://www.crest.org/discuss3.html
-
Other Gasification Events and Information:
http://www.fsec.ucf.edu/bioam/
http://solstice.crest.org/renewables/biomass-info/gasref.shtml
http://solstice.crest.org/renewables/biomass-info/

From Tami.Bond at noaa.gov Tue Sep 4 11:49:41 2001
From: Tami.Bond at noaa.gov (Tami Bond)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
Message-ID: <31ee72c98d.2c98d31ee7@pmel.noaa.gov>

Dear Stovers,

Hi, I'm Tami Bond, a quiet member of this list for some time now. I do
emissions testing when I can drag myself away from my other projects,
and from listening to stove-talk. I'm new, and learning.

I have watched the discussion on holey briquettes. While I have no
experience with the biomass briquettes, I have tested the holey
honeycombs (Coal) that are used in China. Pretty darn good in terms of
particulate emissions. They do make really small particles (<50 nm, you
can't see 'em) but the magnitude is much smaller than that from raw
coal-- like two orders of magnitude fewer particles.

From Tami.Bond at noaa.gov Tue Sep 4 12:11:59 2001
From: Tami.Bond at noaa.gov (Tami Bond)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
Message-ID: <2dd6331301.313012dd63@pmel.noaa.gov>

Hi Ron,

Brief description of what I do and why:

NOAA, among others in climate research, is interested in the properties
of particles in the atmosphere, because these particles can change the
radiation budget in several ways. Two examples are the direct
scattering and absorption of sunlight, and adding particles that can
cause cloud droplets to form. NOAA does not have a program in stove
research. They are supporting my post-doc position because they
believed my proposal, that understanding the characteristics of
particles at the combustion source will help them understand the
particles in the atmosphere. I have another year to prove my point--

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From Tami.Bond at noaa.gov Tue Sep 4 12:14:41 2001
From: Tami.Bond at noaa.gov (Tami Bond)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
Message-ID: <2f1b032ce1.32ce12f1b0@pmel.noaa.gov>

Hi Ron,

(Last message got cut off. I'll try again...)

Brief description of what I do and why:

Before I start the Briquette discussion I should say that I believe
briquette quality varies very much, depending on the coal used to make
it (of course), the fineness of the ground particles, the binder, and
the mixing goodness. I have heard higher emission factors from other
briquettes in China, which were relayed to me by a Chinese colleague. I
also believe that a biomass briquette would be far different due to its
higher volatile content; I only mentioned the coal briquette as
comparison with biomass in my earlier message because I thought the
heat transfer might be similar.

As I have said in several private mails to stovers, please understand
that I am just a beginner and have a lot to learn! So comments about
where I have gone wrong, what information sources I have missed, and
what I can do to help... are most welcome.

> RWL: 1. Can you give us the emissions characteristics in
> quantitativeterms? Can you compare with other stoves or
> combustion processes.

At this point, I can compare briquette emissions with burning raw
bituminous coal. That is not a good comparison, because my
understanding is that these briquettes are made from anthracite. I am
waiting on a shipment right now, which I hope contains some raw coal
from Yunnan province and briquettes made from the same coal. That will
be a better test. Raw bituminous is probably the most polluting coal
there is-- anyone have other opinions?

To be more precise than my earlier message: I measured
- light absorption, similar to Bacharach smoke meter but directly
calibrated to an optical measurement
- light scattering, which for small particles is fairly proportional to
mass
- size distribution & number count

Briquette Bituminous
Absorption m2/kg fuel 0.16 48
Scattering m2/kg fuel 0.10 29
Particles / kg fuel 2.7x10^15 14x10^15

If you want to understand the m2/kg fuel and don't, e-mail me
privately; otherwise just take it as a relative measure. I couldn't
ever get enough mass to weigh from the briquette, to get a mass
emission factor (even when I ran a 22-hour sample!)

> 2. How about carbon monoxide emission measurements or any other
> emissions for these coal briquettes?

Wish I had done that, but didn't. That was a mistake. When I started
doing these measurements I didn't realize how little was known about
stove emissions. I thought I was just refining emission factors that
were already known, to examine the optical properties. Now that I have
the chance to continue a little, I hope to add some gas-phase
measurements. What would *you* suggest?

> 3. Kirk Smith's paper mentioning the holey coal briquettes
> seemed to imply a cancer link. Can you explain that?

Can you tell me which paper? I have a few of his, but can't remember
the holey-coal discussion. Again, the briquettes I have may not be
representative of the average. I may have more thoughts after I read
his paper.

> 4. What explanation do you have for so many fewer particles
> from the briquettes? (Does the size distribution change as well?)

(1) The only paper I've been able to find that discussed briquette
combustion is an "Open File" report from USGS, and that's not about
Asian briquettes. According to that paper, the clay binder actually
takes up the volatile matter as it is released by the fuel, either
catalyzing the combustion or at least causing it to burn
heterogeneously.

(2) Yes, the size distribution does change. The particles from the
briquettes are quite small. My sizing equipment measures down to 20 nm
diameter and the peak in the number distribution appears to be below
that. That size looks like a vaporization/condensation reaction. The
bituminous coal makes a standard, sort-of-lognormal size distribution
with number maximum around 80 nm-- which could be standard soot
formation and growth by coagulation.

"Soot" comes from volatile matter burned in the gas phase. I'm guessing
that either the low volatile content of the original coal, or the
binder, or both, suppresses the soot formation. (Is that noncommittal
enough?)

> 5. I have had the impression that there was considerable
> smokiness in the urban areas becaue of the use of these briquettes -
> can you characterizethe briquettes in terms of smoke? Does the smoke
> change during a burn?

I thought that too. Imagine my delight when I received the coal--
emissions at last!-- and subsequent consternation when NO smoke
resulted! Perhaps "they" only sent me the "good" briquettes? There is
another type of briquettes, also, called "ball coal". These may have
different emissions (and I hope that they, too, are in my coming
shipment).

Another question I have-- which I never did see mentioned on Shell-- is
that there are probably substantial particulate emissions from the food
itself, if one cooks with oil or fries meat. Does anyone have
experience with this?

Anyway, since there wasn't much smoke to see from the briquettes, the
signal-to-noise ratio was too low to see statistically valid
differences between burn conditions. The smoke from bituminous coal
does change during the burn, very nicely. I have real-time measurements
to show it, and will send you the paper if you're interested.

Answers below based on very small sample (three) of interviews with
Chinese folks-- therefore, probably unrepresentative.

> 1. How do you and the Chinese users start these briquettes?

The Chinese use LOTS of wood to start them up, and then they don't let
them go out. They are HARD to light... even acetylene torch doesn't
work; the heat is just drawn away too fast!

I use barbecue briquettes to start them, which is not representative of
practice, but it's otherwise impossible to separate the wood emissions
from the briquette emissions. Kirk Smith pointed out that a proper view
of the system would include the kindling; of course he's right, if one
wants to examine relative merits of fuels.

> 2. Have you seen any computer models for the combustion
> process (that would show the impact of hole size, briquette
> thickness, moisture content,etc)?

No, but I'll post a link as soon as I find one. (Wishful thinking!)

> 3. How many briquettes are typically burned at one time?

One new one for each meal. Three fit in the combustor in a stack. After
the meal, they are left in the stove with inlet closed off (can be used
to heat tea water). At next mealtime, the retained heat is used to
light the new briquette. Bottom briquette--mostly ash now-- is pushed
through the grate; new briquette is put on top; fan is used to perk up
the remainder of the other two old briquettes to light the top new one.
The briquettes are typically burned in a cylindrical clay stove. I'm
wondering if Dean's insulative brick wouldn't be better.

> 4. Is there some statistic like watts per hole? What is
> typical time for consumption of one briquette?

I have no idea about statistics; sorry. At full combustion rate the
briquettes can burn out in ~1.5 hours or so. I didn't run them at full
tilt. I didn't do the Water Boiling Test either, but followed instead
what my interviewees said was typical use pattern. I had to use the
street-vendor size (6") because that's what I was able to get.

> 5. What is the typical briquette thickness?
7.5 cm

> 6. What price (and is this subsidized)? Sold by the piece or
> per kg?
Sold by the piece. I got 20 of them for less than 6 yuan (75 cents?)--
that is, roughly 5 cents apiece. I have no idea if it's subsidized.

> 7. What binder?
Clay, I have heard. But, strangely: A proximate analysis said about 25%
ash. But after combustion, less than 5% of the total mass remained!
Where did the rest of the "ash" go? This is an open question, in my
opinion. It must have escaped as a gas?

> (RWL):
> 1. Do you know of any publications in English on these briquette
> characteristics? How long have they been in use?

No, I don't, but again will let you know if I run into something. It's
my understanding that the Chinese pioneered this technology. One of my
(many) failings is that I do not read Chinese (yet).

> 2. Have you seen the photographs given by Richard Stanley -
> and is the combustion similar? (my guess is that it must be
> less intense because one is dealing with surface combustion rather
> thancombustion of pyrolysis gases - true?)

Exactly right. I never got a red flame out of these briquettes. Blue at
the beginning, then transitioning to milky white and finally just
glowing at the end. I did get a flame-- it wasn't just surface
combustion, but it must have been created by some very light gases that
wouldn't soot.

> 3. In your work, are you able to control the air flow?

In the measurements I discussed, the air flow was only crudely
controlled-- like what the locals would do, covering up the combustor
inlet to slow combustion. I am hatching plans for better-controlled
combustion (more on that privately, if you're interested). It's hard to
control the air flow when using a 'representative' combustor, and that
was the goal of the first experiments.

> 4. How many holes for both the 4" and 6" sizes? What
> diameter holes?

I don't know about the 4" size because I haven't seen it. The 6" have
~15 holes of 1.25 cm diameter each. (Sorry for mixing units)

> 5. Charcoal extinguishes itself quite quickly in the absence
> of air (when put into a sealed can) - would the same be true for a
> coal briquette?

One would think so. I never tried that because, like I said, the
practice is generally that once started, you try *not* to let them go
out.

> Tami - Thanks very much for giving us these insights. Sorry for
> dumping all these new questions on you,

Really, I have learned so much here and from Shell, that it is my
pleasure to return the favor in any small way I can. And please feel
free to tell me if I need to clarify anything I have said. I know that
not everyone here is a 'techie'; in fact, that is one of the delights
of this list.

Sincerely yours,

Tami

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From tombreed at home.com Tue Sep 4 12:34:38 2001
From: tombreed at home.com (Thomas Reed)
Date: Tue Aug 31 21:37:00 2004
Subject: Radiation trapping in holes...
In-Reply-To: <4.3.1.2.20010902130552.01a29580@mail.ilstu.edu>
Message-ID: <01e101c13487$ef3a76e0$18e5b618@lakwod3.co.home.com>

Dear Paul, Tami, Ron and all:

See earlier note on radiation trapping by holes in
briquettes.

We need to get the coal briquette people together with the
biomass briquette people to see what they have in common and what's
different...

TOM REED

Dr. Thomas Reed
The Biomass Energy Foundation 1810 Smith Rd., Golden, CO 80401303
278 0558; tombreed@home.com; <A
href="http://www.woodgas.com">www.woodgas.com
<BLOCKQUOTE dir=ltr
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Ron
Larson
To: <A title=psanders@ilstu.edu
href="mailto:psanders@ilstu.edu">Paul S. Anderson ; <A
title=ajmalawene01@hotmail.com
href="mailto:ajmalawene01@hotmail.com">Apolinário J Malawene ; <A
title=bobkarlaweldon@cs.com href="mailto:bobkarlaweldon@cs.com">Bob and Karla
Weldon ; Ed
Francis ; <A title=rstanley@legacyfound.org
href="mailto:rstanley@legacyfound.org">Richard Stanley ; <A
title=rwalt@gocpc.com href="mailto:rwalt@gocpc.com">Robb Walt ; <A
title=stoves@crest.org href="mailto:stoves@crest.org">stoves@crest.org ;
<A title=tombreed@home.com
href="mailto:tombreed@home.com">tombreed@home.com ; <A
title=ajtsamba@zebra.uem.mz
href="mailto:ajtsamba@zebra.uem.mz">Tsamba--Alberto Julio ; <A
title=clucas33@yahoo.com
href="mailto:clucas33@yahoo.com">clucas33@yahoo.com ; <A
title=clucas@zebra.uem.mz
href="mailto:clucas@zebra.uem.mz">clucas@zebra.uem.mz
Sent: Sunday, September 02, 2001 8:05
PM
Subject: Re: Briquettes with holes

Hi Paul -

Thanks for your report.
See some notes and questions below.
<BLOCKQUOTE
style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Paul S.
Anderson
To: <A title=ajmalawene01@hotmail.com
href="mailto:ajmalawene01@hotmail.com">Apolinário J Malawene ; <A
title=bobkarlaweldon@cs.com href="mailto:bobkarlaweldon@cs.com">Bob and
Karla Weldon ; <A title=cfranc@ilstu.edu
href="mailto:cfranc@ilstu.edu">Ed Francis ; <A
title=rstanley@legacyfound.org
href="mailto:rstanley@legacyfound.org">Richard Stanley ; <A
title=rwalt@gocpc.com href="mailto:rwalt@gocpc.com">Robb Walt ; <A
title=stoves@crest.org href="mailto:stoves@crest.org">stoves@crest.org ;
<A title=TOMBREED@HOME.COM
href="mailto:TOMBREED@HOME.COM">TOMBREED@HOME.COM ; <A
title=ajtsamba@zebra.uem.mz
href="mailto:ajtsamba@zebra.uem.mz">Tsamba--Alberto Julio ; <A
title=clucas33@yahoo.com
href="mailto:clucas33@yahoo.com">clucas33@yahoo.com ; <A
title=clucas@zebra.uem.mz
href="mailto:clucas@zebra.uem.mz">clucas@zebra.uem.mz
Sent: Sunday, September 02, 2001 12:07
PM
Subject: Briquettes with holes

Briquettes with holesDear Stovers
and Friends,My goodness, we all have been quiet for the past
weeks.Here is a summary of my current efforts and
thoughts:One issue is the holes in the briquettes. I wanted to
test having multiple (3 or 4) holes in the standard briquettes advocated by
Richard Stanley and the Legacy Foundation, of which I am a believer and
advocate.I took an existing 4 inch (10 cm) diameter (and about 5
inches 13 cm high) recycled biomass briquette that had one hole. I
plugged the center hole (not very well, but sufficient) with the same
materials that I cut out of the briquette when I DRILLED three holes down
through the diameter-side. The drill bit said 5/8th inch (about 1.5 cm), being slightly smaller than
the standard center-hole in Richard’s briquettes.
After some “playing around”, I
wrapped the briquette fairly tightly in a piece of thin sheet metal (easily
cut with tin-snips), tied it with a discarded wire coat hanger, and thereby
created a cylinder about 8 inches (20 cm) high. [Therefore, there was
some chimney effect.] Plenty of air was available through the bar-b-q
grill under the cylinder.Wow, did it burn well!! All three
holes were shooting flames. No detectable smoke (the “eyes and nose”
test). Sorry, no photograph yet available. But it looks like
Richard’s pictures of flames from a central hole, but this time with 3 holes
blazing away.

(RWL): Q1a. Could you tell us
a bit about your lighting - from the top or bottom?
(Either?)

Q1b.
Easier now to light - with the wrap around "chimney"?

Q1c. What
happened after the briquette had pyrolyzed? Was there a distinct
change in power output? Would it be feasible to stop the action - or
instead increase air flow?
Second: That lowly test
(plus my limited experiences making and burning briquettes in my backyard
and in Mozambique) leads me to the following items, each of which needs
additional research:1. There is a wealth of heat-generating
benefits from having different numbers of holes in the
briquettes.2. They can be made easily using the same
technology as the single-hole ones. (Ed Francis and I are working on
making the piston / press-plunger for multiple holes.)
Note: We can use the same 4-inch (inside diameter PVC pipe) for the
cylinder.3. The stove needs to snuggly hold the briquette (to
minimize the outside burning, where temperatures are lower and combustion is
less efficient/effective).

(RWL): I'd
like to see a test where the fit was not so snug. I believe there
might be very little (or no) combustion on the outside. A little
extra air on the outside might provide cleaner burning (especially late in
the process). How much above the 8" metal cylinder did the flames
appear (at first, at maximum, and at the end)? Now we are
talking about the emissions from the flame - do you have any access to any
emissions monitoring equipment? 4. The 4-inch (10 cm)
diameter is possibly too SMALL. I want to experiment with briquettes
that would just fit into a standard “number 10 tin” (which is American
talk for a metal can about 7 inches (18 cm) in diameter and about 8 inches
(20 cm) high.
(RWL):
This may be a bit wider than needed for the test described above - but it
certainly sounds like another good test. I would also like to
see tests of briquettes (and chimneys) of different heights. Also
replacing the metal surrounding with ceramics is probably a worthwhile.test
to increase efficiency.
5. Technically, there is no
requirement that the briquette is round. Square ones could fit
together better in a larger stove. Although this is a
relatively minor issue at present, I believe that commercially produced
(home industry) large briquettes might give some significant advantages when
placed in “better” (probably larger and more costly) stoves with special
characteristics such as are mentioned in the next item.6. A
stove (even a small one for a standard-size briquette) could be made in
which the briquette with a “standardized” hole configuration would rest on a
base plate that has the desired number of properly spaced 2 or 3 cm holes
(for air) in the plate. Those holes could be easily closed (use
“plugs” or stoppers or sliders of metal?) or opened so that burning could be
somewhat controlled. For example, ignite 4 holes but later shift back
to only 2 or one, or almost none as in the “slow-combustion stoves” that I
know of from Brazil and Australia.

(RWL): All good ideas. Rotation of one set of holes
past another similar set is another possibility.
7. Couple all of this with the
varieties of briquette materials (I am thinking of the 40% charcoal “dust”
briquettes we are making in Mozambique for experiments) and you could have
some major “user-control” of the types of fires available.

(RWL): Agreed
- I hope you will keep in mind the possibility of producing charcoal at
the same time. I am concerned you may not be getting very good
combustion in the late stages.So, I will continue to have fun with
the briquettes project. Your comments will be carefully
studied. We need LOTS of help and further experimentation of all
types in different settings.
(RWL):
Any chance of shipping some of these to others?
And to Ron L and others: Does
anything said above make enough sense to get included into someone’s grant
proposal for Shell Foundation or other sources? IF yes, please let me
know. I would be very interested in being part of a team
effort.
(RWL): I
still like everything I hear about holes in briquettes. If the idea is
indeed new and you can prove especially something about lowered emissions, I
presume that the Shell Foundation would find a proposal to be of
value. Your discussion above talks also about controllability, which
is a major plus. You and Richard Stanley would seem to have a lead in
this type of research. Because you have given this suggestion to
several hundred "stoves" list members - maybe they will also be writing
you. Hard to say which is the best way for those of you who have been
promoting "holey" briquettes - and it depends a lot on what you want to
do. Your expression of interest is presumably a good first step to
finding partners. If you don't hear, you presumably have to send in a
proposal yourself.

The Shell Foundation meeting
is on October 11-13, with a report coming out some time thereafter -
possibly with a number of different requests for proposals. I guess it
will be hard to ask for proposals to be received sooner than December -
probably later. I think about at least 10 of that group will be
reading your notes - and would like to hear your recommendations (as well as
from anyone else on the "stoves" list).
I am SOOOOOO sorry that I will not be
attending the biomass conference in September in Orlando. I would
learn a lot and meet many of you. But I am just an amateur and a true
beginner with this stoves stuff.Having fun
!!Paul
(RWL): Glad to receive your reports and that you are having
fun..

I have just started reading
a doctoral thesis on pyrolysis (both modeling and experiments) and will send
a report on it soon - that I think will give some other good insights on the
processes you have been investigating. For instance, surface
temperature is clearly an important property - and shows why an interior
hole is so much better than an exterior wall.

We are mostly
amateurs. If there were lots of real expertise around (and if the
rural stove problem was an easy one), we would have already heard a lot
about "holey" briquettes and lots of other "perfect" stove topics. I
believe what you are doing will prove to be a very good lead on making
better stoves. Hope you can keep it up.

Best of luck and again
thanks for an important report.

Ron

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 -
7/00
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice:
309-438-7360; FAX: 309-438-5310E-mail: psanders@ilstu.edu
- Internet items: <A href="http://www.ilstu.edu/~psanders"
EUDORA="AUTOURL">www.ilstu.edu/~psanders

From ronallarson at qwest.net Tue Sep 4 12:48:47 2001
From: ronallarson at qwest.net (Ron Larson)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
In-Reply-To: <31ee72c98d.2c98d31ee7@pmel.noaa.gov>
Message-ID: <001801c1348f$8ce26720$15b46441@computer>

Tami:

Thanks for your note below - to which I have inserted a few questions.

Ron

----- Original Message -----
From: Tami Bond <Tami.Bond@noaa.gov>
To: <stoves@crest.org>
Sent: Monday, September 03, 2001 6:12 AM
Subject: Re: Briquettes with holes

> From my observation the combustion is stabilized by the radiant
> feedback within the hole. The honeycomb briquettes are fairly dense,
> with low volatile content (and very hard to light). Keeping combustion
> going requires maintaining sufficient heat for reaction. This is a
> competition between the heat generated by oxidation and heat drawn away
> by conduction into the briquette. Up to a point, I would guess that
> with more holes, (a) more heat is generated, (b) the briquette is
> warmer inside, (c) the heat transfer from the surface to the interior
> of the briquette is lower, since heat transfer is proportional to the
> temperature difference. So more heat stays at the surface to maintain
> reaction. Even after my briquettes are burning well there is not much
> combustion around the outside.
>
RWL: I think you are exactly right in your explanations. Apparently
with biomass pyrolysis, there is a sizeable energy loss from the surface
caused by the exiting gases - that you have much less of.

1. How do you and the Chinese users start these briquettes?
2. Have you seen any computer models for the combustion process (that
would show the impact of hole size, briquette thickness, moisture content,
etc)?
3. How many briquettes are typically burned at one time?
4. Is there some statistic like watts per hole? What is typical time
for consumption of one briquette?
5. What is the typical briquette thickness?
6. What price (and is this subsidized)? Sold by the piece or per kg?
7. What binder?

> It is hard to stop these coal briquettes from burning once you have
> started them. This would be a disadvantage to making a larger
> briquette. I have heard that in China, people just cover the stove
> inlet to slow the combustion down. The homeowners tend to use about 4"
> briquettes and the larger ones I have tested (6") are used by street
> vendors. The biomass briquettes may perform entirely differently.
>
(RWL):
1. Do you know of any publications in English on these briquette
characteristics? How long have they been in use?
2. Have you seen the photographs given by Richard Stanley - and is the
combustion similar? (my guess is that it must be
less intense because one is dealing with surface combustion rather than
combustion of pyrolysis gases - true?)
3. In your work, are you able to control the air flow?
4. How many holes for both the 4" and 6" sizes? What diameter holes?
5. Charcoal extinguishes itself quite quickly in the absence of air
(when put into a sealed can) - would the same be true for a coal briquette?

> Sincerely yours,
>
> Tami
>
<snip>

Tami - Thanks very much for giving us these insights. Sorry for
dumping all these new questions on you, but you have a rare insight that
will undoubtedly help Richard Stanley, Paul Anderson, and others with their
work - as well as possibly influencing the forthcoming Shell Foundation
dialogs.

If I haven't gotten in the right questions, please feel free to direct
us to a report or paper - or to answer the right questions. Please also
feel free to tell us more about the work of NOAA on this and similar topics.

Ron

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From rstanley at legacyfound.org Tue Sep 4 13:46:48 2001
From: rstanley at legacyfound.org (Richard Stanley)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
In-Reply-To: <4.3.1.2.20010902130552.01a29580@mail.ilstu.edu>
Message-ID: <3B9431BF.90346C1D@legacyfound.org>

Paul:
Great stuff . We tried similar experiments in 1994 but found it too
hard for the producers to get the material into a multi holed mold
/die configuration???in a regular basis??and they were very good at
molding three plus briquettes per minute with the single hole
whereas they could not get to half this amount with the multi hole
configuration . Admittedly this is with the veryt basic and very
replicable and rugged batch fed press you are now using.
Ref size, the briquette project began with godfather Ben Bryant's experiments
on 6" dia. briquettes with single 2" dia. holes. The
problem we had in Malawi with this size was that they were to large
for the home cook stove in Malawi - and this was pretty much
our target development market for the project. Sure more holes and
a tighter side works well but if your goal is to produce briquettes
in a microenterprize setting you have to really think about practicality
in a production setting. We had tried a hexagonal configuration
of holes about the center but this forced exact alignment to the piston
and a relatively more fluid mixture to assure even distribution.
Additionally we usually make two a t a time so the dividing plate inserted
after one charge is added would as well have to fit exactly.
That is lots harder to accomplish with traditional folks and low tolerances
six months after you are gone from the scene, than it may
seem. I recognize that the Chinese holey briquettes made largely from
charcoal fines are multi-holed but they are as well made with
fabricated steel machinery where tolerances are controlled much more
tightly. Others, still, inject the charge to a continuous feed
press where one can maintain some degree of control on the position
of the guide rods (the guide rods generally being rigidly
attached to the piston).

As to square or hexagonal or triangular shapes sure they would all work
. We have just stuck with the round shape because 1) it
burns more evenly and 2) most village household stoves are round not
square. There is no other reason I know of that one could not
make them any shape one desired.
Interesting double bind approach to the validation of the effect of
single or multiple holes   is to bore a single or multiple hole
(s)
through a lathe-turned chunk of wood and compare that burn to same
chunk without the hole(s). This rather nicely sews up the
rationale for at least one hole, in that the material would be a constant
and the only real variable would be the hole, single or
whatever configuration you choose. (My results are quite evident that
the hole had a dramatic effect. I did not get numbers on the
experiment as at the time I was simply trying to justify to myself
the entry into holey briquettes and was far more concerned with
adaptability of the resource to micro enterprise based production for
rural energy needs.
We are indeed trying to approach Shell foundation for funding for extension
of the technology through a training and R&D center in
the developing nations and for development of a higher volume production
device for global application. You could join in as one to
experiment with burning aspects and a field site in Mozambique with
which to apply it.
I open this offer to anyone of us on the list. We may well derive a
better briquette and possibly stove, as one part of the proposal, but I
would ask that we all think about application. Those of us out with development
project management experience need to be involved to make the technology
have impact. Lets put our heads together for a set of simultaneous and
well monitored and documented pilot projects over a broad area . Our friends
as producers and trainers in Kenya, Malawi, Mali, Haiti, in
West Africa and Haiti and shortly in southern Mexico/ Northern Guatemala.
Lets engage them in training trainers in related areas where possible,
such that, as experiments on the optimum number of holes or briquette size
are concluded, we would have a full cadre of persons familiar with the
basic process and able to readily produce the briquettes, (guiding the
rest of us as they go).
Hope to see as many of you as possible at the biomass conference
where we will make a few on the basic mini press during the talk.
Wholesomely yours,
Richard Stanley

"Paul S. Anderson" wrote:
Briquettes with holes
Dear Stovers and Friends,
My goodness, we all have been quiet for
the past weeks.
Here is a summary of my current efforts
and thoughts:
One issue is the holes in the briquettes.
I wanted to test having multiple (3 or 4) holes in the standard briquettes
advocated by Richard Stanley and the Legacy Foundation, of which I am a
believer and advocate.
I took an existing 4 inch (10 cm) diameter
(and about 5 inches 13 cm high) recycled biomass briquette that had one
hole. I plugged the center hole (not very well, but sufficient) with
the same materials that I cut out of the briquette when I DRILLED three
holes down through the diameter-side. The drill bit said 5/8th
inch (about 1.5 cm), being slightly smaller than the standard center-hole
in Richard’s briquettes.
After some “playing around”, I wrapped
the briquette fairly tightly in a piece of thin sheet metal (easily cut
with tin-snips), tied it with a discarded wire coat hanger, and thereby
created a cylinder about 8 inches (20 cm) high. [Therefore, there
was some chimney effect.] Plenty of air was available through the
bar-b-q grill under the cylinder.
Wow, did it burn well!! All three
holes were shooting flames. No detectable smoke (the “eyes and nose”
test). Sorry, no photograph yet available. But it looks like
Richard’s pictures of flames from a central hole, but this time with 3
holes blazing away.
Second: That lowly test (plus my
limited experiences making and burning briquettes in my backyard and in
Mozambique) leads me to the following items, each of which needs additional
research:
1. There is a wealth of heat-generating
benefits from having different numbers of holes in the briquettes.
2. They can be made easily using
the same technology as the single-hole ones. (Ed Francis and I are
working on making the piston / press-plunger for multiple holes.)
Note: We can use the same 4-inch (inside diameter PVC pipe) for the
cylinder.
3. The stove needs to snuggly hold
the briquette (to minimize the outside burning, where temperatures are
lower and combustion is less efficient/effective).
4. The 4-inch (10 cm) diameter is
possibly too SMALL. I want to experiment with briquettes that would
just fit into a standard “number 10 tin” (which is American talk
for a metal can about 7 inches (18 cm) in diameter and about 8 inches (20
cm) high.
5. Technically, there is no requirement
that the briquette is round.   Square ones could fit together
better in a larger stove.    Although this is a relatively
minor issue at present, I believe that commercially produced (home industry)
large briquettes might give some significant advantages when placed in
“better” (probably larger and more costly) stoves with special characteristics
such as are mentioned in the next item.
6. A stove (even a small one for
a standard-size briquette) could be made in which the briquette with a
“standardized” hole configuration would rest on a base plate that has the
desired number of properly spaced 2 or 3 cm holes (for air) in the plate.
Those holes could be easily closed (use “plugs” or stoppers or sliders
of metal?) or opened so that burning could be somewhat controlled.
For example, ignite 4 holes but later shift back to only 2 or one, or almost
none as in the “slow-combustion stoves” that I know of from Brazil and
Australia.
7. Couple all of this with the varieties
of briquette materials (I am thinking of the 40% charcoal “dust” briquettes
we are making in Mozambique for experiments) and you could have some major
“user-control” of the types of fires available.
So, I will continue to have fun with the
briquettes project. Your comments will be carefully studied.
We need LOTS of help and further experimentation of all types in different
settings.
And to Ron L and others: Does anything
said above make enough sense to get included into someone’s grant proposal
for Shell Foundation or other sources? IF yes, please let me know.
I would be very interested in being part of a team effort.
I am SOOOOOO sorry that I will not be
attending the biomass conference in September in Orlando. I would
learn a lot and meet many of you. But I am just an amateur and a
true beginner with this stoves stuff.
Having fun !!
Paul

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique
8/99 - 7/00Dept of Geography - Geology (Box 4400), Illinois State UniversityNormal,
IL 61790-4400   Voice: 309-438-7360; FAX:
309-438-5310E-mail: psanders@ilstu.edu - Internet items:
www.ilstu.edu/~psanders

From ronallarson at qwest.net Tue Sep 4 15:01:57 2001
From: ronallarson at qwest.net (Ron Larson)
Date: Tue Aug 31 21:37:00 2004
Subject: Help me with a Question--PLEASE (on charcoal combustors)
In-Reply-To: <2195-3B92EBB1-782@storefull-211.iap.bryant.webtv.net>
Message-ID: <023e01c13423$6d56f680$a1b16441@computer>

Nadine:

Wo, you are fast!. Thanks for the information on the 1965 Barbecue
book - maybe I can find it.
Good luck

With the lava rocks, there could be adequate air flow up from below.
Then it would be interesting to try some experiments with holes in the inner
foil.

Ron

----- Original Message -----
From: "nay" <NB-1@webtv.net>
To: Ron Larson <ronallarson@qwest.net>
Sent: Sunday, September 02, 2001 8:32 PM
Subject: Re: Help me with a Question--PLEASE (on charcoal combustors)

>
> Ron, thank you so much on your timely response. I'm going to give this
> method a try
> using the Lava Rocks. I'll keep you informed on how it turns out---or
> just look at your major news network---and if you here of an explosion
> in NY----you know it was Nay.
>
> Better Homes & Gardens
> Barbecue Book
>
> Meredith Press
> New York---Des Moines
> Meredith Publishing Co
> 1965
>
> This book also has info on
> Smokers, outdoor Stoves
> just alot of stuff to do with
> Fire, radiant Heat & outdoor cooking
> how people cooked in the 17-1800'S
>
> Thanks again
> ...................Nadine
>
>

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From psanders at ilstu.edu Tue Sep 4 15:13:45 2001
From: psanders at ilstu.edu (Paul S. Anderson)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
In-Reply-To: <4.3.1.2.20010902130552.01a29580@mail.ilstu.edu>
Message-ID: <4.3.1.2.20010904140044.01a2d8e0@mail.ilstu.edu>

Reply is below RE:

At 06:43 PM 9/3/01 -0700, Richard Stanley wrote:
>
>Paul:
>
>Great stuff . We tried similar experiments in 1994 but found it too hard
>for the producers to get the material into a multi holed mold
>/die configuration???in a regular basis??

Richard and Stovers,

Thanks for the reply (and I also saw the extra paragraph on the message to
the Stoves listserv.)

I suspected that you had made multiple-hole briquettes before. And I
expect to encounter similar problems of production.

I and my Mozambican co-workers would welcome any role in proposed research
and development grants, etc., with you, and with others where appropriate.

I re-emphasize that micro-industry and business development for local
people is NOT my primary focus. I think that production for
self-consumption (and sell any surplus?) is a useful approach where
millions are unemployed or under-employed. So "speed" or efficiency of
production are of only minor interest to me.

To answer Ron's and Tami's messages, I do not have any means of accurate
testing, but as issues develop I will seek such expertise in central
Illinois and in Mozambique (probably with Carlos at the Engineering Dept
at Univ. Eduardo Mondlane.)

Is there a picture (or good description) of the China (or elsewhere)
briquettes / coal with holes? Size and position of holes, etc.

Tom Reed mentioned Boy Scouts and the "radiation cavity" or "radiation
capture". In my recent (1990s) scouting, those principles were not
mentioned nor even hinted. Just make a fire, and it must get hot enough
to burn.

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From psanders at ilstu.edu Tue Sep 4 16:53:27 2001
From: psanders at ilstu.edu (Paul S. Anderson)
Date: Tue Aug 31 21:37:00 2004
Subject: Briquettes with holes
In-Reply-To: <2f1b032ce1.32ce12f1b0@pmel.noaa.gov>
Message-ID: <4.3.1.2.20010904150320.01a3a550@mail.ilstu.edu>

Stovers,

Tami's latest message was filled with great info. Here are some
observations (I hope I get this right.) (I love the metric system, but
this time I use English measures.)

1. coal briquette with holes (China): 3 inch high, 6 inch diameter (about
28 square inches surface), 15 holes each about 5/8th inch diameter ( about
4.6 sq inches of holes total), hard anthracite coal, very hard to ignite
initially, burns 1.5 hours at full burn, burn one during cooking, then cut
back air to hold the stove unit hot until next meal when add one more
briquette, used in a cylindrical stove that holds 3 briquettes (3x3 inches
high = 9 inch height), but only really burning one at a time thereby having
about 5 - 6 inches of chimney effect, burns very hot and without flame, and
low noxious emissions; briquette is industrially produced and marketed at
prices of about 5 cents US each (maybe is subsidized), which is 15 cents
per day times 30 = US$4.50 per month or $54 per year.)

2. In my humble opinion, although this technology seems to work for China,
I feel it is not likely to be of much application in Africa, Latin America,
or southern Asia, at least not in the near or mid-future.

3. We have the basis for someone's thesis/dissertation: The relationships
(plural) between hard-to-start long-burning (hours and whole days)
industrally-processed briquettes (mainly coal) verses easy-to-start,
short-duration (30 minutes and can add more) personally-made briquettes
(mainly biomass). And there are probably intermediate "products" in some
continuum.

4. And foundations like Shell would do well to support numerous thesis
studies to be conducted in the universities in the Developing Countries.

5. But I personally must go back to the point of view well expressed by
Richard: We need to keep our focus on applications that can be accepted
into the lifestyles of the resource-poor people who could benefit from
these innovations.

Paul

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:bioenergy@crest.org>
List-Help: <mailto:bioenergy-help@crest.org>
List-Unsubscribe: <mailto:bioenergy-unsubscribe@crest.org>
List-Subscribe: <mailto:bioenergy-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From lanny at roman.net Tue Sep 4 22:39:07 2001
From: lanny at roman.net (Lanny Henson)
Date: Tue Aug 31 21:37:00 2004
Subject: Lanny's Stove Project
In-Reply-To: <007901c12506$265942a0$1dba3cd0@default>
Message-ID: <014801c135b3$4d9ae720$37ba3cd0@default>

Ron and Stovers,
Ron, thank you for the excellent answers about the CO and wood gas. Your
information will be helpful with my next prototype. I hope I did not cost you
too much time with my elementary questions.

My goal with this stove project is to design practical stoves for use by
people in developing countries.
A practical stove for this application as I see it now should:
Burn clean and possibly be vented because of IAP (indoor air pollution).
Be user-friendly, light quickly and burn steadily for an hour with little
attention.
Be a design that can be built with inexpensive and/or local materials and
local labor.
Be flexible in the biomass fuels that it will burn, including densified and
undensified bulky biomass like sawdust.
Be a flexible burner design that will adapt to a flat griddle, pot, oven or
grill.
Be fuel-efficient.
The rocket stove with its clean combustion looks efficient and simple to
build. It also seems like it could be flexible in its uses, but it requires a
lot of attention to hand feed the small pieces of fuel into the grate. It would
be good if we could make it burn steadily for longer periods and be more
flexible in the types and sizes of fuels that it can burn.
So, my first prototype is an attempt to couple a gravity fuel feed to the
rocket burner to achieve a long and steady burn. I built something quick and
simple just to see if fuel will continuously feed into a rocket and burn with
the ashes falling through a grate and without clogging.
This prototype #1 is a 4" 14 ga steel tube (pipe) with a grate in the bottom.
The top is cut at an angle because it came from the scrap pile that way. To this
I have welded a wye branch of 3" pipe at 30 something deg. It has a slide gate
damper on the end. The 4" rocket leg is longer than the 3" fuel leg. For a stand
I welded a pipe that I can stick into the ground.
Burn 1. I dropped in a handful of twigs (dead wood-fallen limbs) and 4
Kingsford charcoal briquettes. The twigs quickly lit. The smoke turned clear and
it began to roar.
***Some air was flowing down the fuel leg and out the exhaust leg in a
siphoning action.
After the wood burned down, the charcoal began to burn but did not generate
the heat and flow that the twigs did with their secondary combustion. Twigs
added to the 3" fuel leg did not cover the grate well, so I added the twigs to
the 4" rocket leg, and that worked. I blew my breath down the long 4" leg, and
the fire temporary switched to the shorter 3" leg. It looked promising.
The only sawdust /shavings that I had were wet, but I decided to try to burn
some anyway. I added more twigs and tried to gradually added the sawdust. I had
some burning, but the moisture evaporating carried away the heat and the fire
went out.
I was optimistic, but it was obvious that the 4" rocket leg wanted to be the
fuel hopper leg and that the 3" leg was in the best position to be the rocket
leg. It was also obvious that it wants to burn biomass and not charcoal and that
it does not like wet sawdust.
Burn 2. I switched fuel and rocket legs by adding a section to the 3" leg to
make it longer than the 4"leg. Twigs burned fine but the prototype had trouble
with larger pieces of 3" dia dense hickory wood. The burn zone was too short and
there was too much heat loss (no insulation). My sawdust/shavings had dried some
but I could feel some moisture. I started with twigs and added 2 briquettes of
charcoal then added some sawdust. I was able to get some clear burning with some
poking and shaking, but it would go out without constant attention.
It was obvious that I had too much moisture and too much excess air.
Burn 3. To limit the airflow, I laid a flat plate to the top of the fuel leg
and added a snap on channel shaped sheet metal cap to the bottom of the grate
end. This photo does not show the bottom cap. <A
href="http://www.roman.net/~lanny/rocket1.jpg">http://www.roman.net/~lanny/rocket1.jpg.
This cap will slide to adjust the airflow. I added twigs ,then gradually added
air-dried sawdust/shavings. With some tweaking of the bottom plate I got a clear
burn. I filled the fuel leg with sawdust and it continued to burn. It would
occasionally sputter and pulse. When I poked through the grate, the sawdust
shifted and blocked the airflow to the wye joint where the secondary combustion
takes place. White, thick smoke flowed, but in a few seconds a new airway had
burned into the secondary combustion area, and the smoke cleared. This
encouraged me.
Burn 4. I filled the fuel leg to the top with twigs using thumb size pieces
and smaller to start. It lit quickly and burned clear and almost steady for 25
min. All the fuel burned with no help, but I had to clear the ashes once (no ash
storage). Then I successfully burned a load of sawdust. The airflow setting that
worked was to slide the bottom plate forward toward the wye joint side. This let
primary air enter through the back, thickest part of the fuel. Then I tilted the
plate down in front to let the secondary air in the opposite side, which took
the shortest pathway to the secondary combustion area. It works!
*** I noticed that sawdust clumps together as it burns. We may be able to use
this to our advantage.
I did not want to invest too much of my limited resources into this
prototype, which was only intended to see if fuel and ashes would flow through
the rocket. Now I know that is possible. I am very pleased with its performance
and now I am fired up and moving forward to the next prototype #2.
The next prototype #2 will be flexible so I can test many setups. It will
have an adjustable height and pitch grate, ash storage, heated secondary air
with mixing into the combustion zone, insulation or jacketing, better primary
and secondary air control, and an easily replaceable rocket leg, so I can test
different ways to introduce the secondary air. I will also increase the fuel
hopper size to accommodate larger firewood size pieces of wood and more of the
bulky type fuels.
It will soon be time to start testing for emissions from #2. The only clue
that I have now is clear exhaust.
I also need to start thinking about what inexpensive and/or local materials
to use for construction.
A few things I need to know are:
How do I test for moisture content of fuel?
What emissions do I need to test for? CO, particulate and ?
What equipment/instruments will I need to test for those emissions?
Lanny lanny@roman.net
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Ron
Larson
To: <A href="mailto:lanny@roman.net"
title=lanny@roman.net>Lanny Henson ; <A href="mailto:stoves@crest.org"
title=stoves@crest.org>stoves@crest.org
Sent: Monday, August 20, 2001 11:51
PM
Subject: Re: Lanny's Stove Project

Lanny and Stovers:

Sorry for not getting back to
you sooner. Your first message came at a bad time as the "Shell" dialog
was dying down. Below are a few first answers:
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Lanny Henson

To: <A href="mailto:stoves@crest.org"
title=stoves@crest.org>stoves@crest.org
Sent: Tuesday, August 14, 2001 3:12
PM
Subject: Lanny's Stove Project

Lanny's Stove Project
My name is Lanny Henson. I became a subscriber to this list about 3 years
ago. I was looking for information about charcoal and clean combustion
because I was designing a barbecue cooker. The cause of this list has stuck
my interest and I think that it would be fun to design some stoves so I am
going to spend some hobby time and build a few. I have a background in
designing and fabricating airflow systems and custom sheet metal parts.
(RWL): This is a
great time to raise this issue, as the subject of clean combustion of
charcoal is not well understood by most of us. Your background
with air flow is perfect to help us all out.

>I have a few questions before I start.
>1 Can you feed limited air to charcoal and get an efficient burn?
Does charcoal need secondary air to burn efficiently? What causes CO and is
energy wasted if it does not get to CO2?
(RWL): Q1 - I say
no, but am a little nervous about this answer because of your next question
about secondary air. You need to have sufficient air eventually,
but maybe this can be done in two stages. For most charcoal ue
however, I think it is safe to say there is only a single air supply.
We talk about primary and secondary air when we are describing a
charcoal-makings stove.
Q2. My answer is no - not necesssary - but again
maybe a possibility. Very close to the charcoal surface, I believe we
are getting CO - but we have CO2 shortly thereafter.
Q3. CO certainly comes from a situation
with insufficient air - and yes there is energy loss if the reaction to get
CO does not continue to get the CO2. But we are more
concerned these days in the health aspects of CO - people die from charcoal
fires emitting too much CO. On the "shell" list recently we have heard
of national or world standards. Let us know if you want those numbers
on what is considered safe.
In the case of CO2 flowing past hot charcoal, you
can also have the reaction CO2 + C = 2 CO - which is a good reaction if you
desire the gases (and then you certainly need secondary air).
>2 What is the ratio of combustion air needed to burn wood gas?
Someone wrote 6 to 1. If this is correct, would that be >6 parts gas and
one part air?
Lanny Henson
(RWL): In order to get some practice on
this sort of thing, I went to the web site called "<A
href="http://www.woodgas.org">www.woodgas.org" (maintained by Tom Reed)
and found a formula for wood gas as 20% CO, 12% H2, 3% CH4, 15%
CO2, and 50% nitrogen. Using the molecular formulas above and
molecular weights of 12 for C, 1 for Hydrogen, and 16 for O, you can do a
chemical balance using mole equivalents, which for the first three
ingredients (if the total is 100 grams) are 20/28 = .71; 12/2= 6, and 3/16 =
.1875, so we need (.71+6)/2 + 2*.1875)=3.73 moles or 3.73*32=119 grams of
Oxygen. Because the air is only about 23 % oxygen (this is by weight,
not by volume - which is 0.21), then the air needed is larger by a factor of
about 1.19/.23= 5.18 which is pretty close to the factor of 6 which you cite
(but not in your direction - the weight of the required air is the
larger). Practically, to get complete combustion, you need
to think of at least the factor of 6.
In case (like me) you are
rusty on this sort of chemistry - a mole is the number in grams of
the molecular weights of each part of the formula. So one mole of
CO (weight 28) reacts with one/half mole of O2 (or 1/2 of 32 grams = 16
grams) to give one mole of CO2 (weight 44 grams). A mole always
contains the Avogadro number of molecules - 6.02 E23. Three more
numbers may be helpful. The production of CO2 releases 94 kcal per
mole (or per 12 grams) of C; the production of water releases about 69 kcal
per mole (or 2 grams) of hydrogen; and 1 kilocalorie is 4.187
kilojoules.
But I am pretty sure you will
not be using woodgas, in any way, with your starting fuel of charcoal.
Assuming this is mostly carbon, the right formula is C+O2 = CO2. This
means every 12 grams of charcoal (carbon) requires 32 grams of oxygen and
32/0.23 = 139 grams of air. Thus the weight ratio for your barbecue
should be about 139/12 = 11.6 (about twice the number above). But even
this is not a good number - as you need an excess air ratio to make sure you
are producing very little CO. If you only consume half the oxygen in
your air stream, you will need about 23 times as much weight of air as of
charcoal. From the numbers here you should find an energy number close
to 30 Megajoules per kilogram of charcoal. If you convert a kg of
charcoal in an hour, the power is 30E6 Joules/3600 seconds or about 8.3
kJ/sec = 8.3 kWatts. As air density at ambient temperatures
is around a kg per cubic meter, this will take around 20-25 cu meters
of air.
Sorry for the delay getting
back to you. I hope someone else will check my work. It has been
a long time since we on this list went through these sort of
computations (if ever). So we now look forward to hearing how you
handled the clean charcoal conversion problem. Remember what we want
is how to get very low CO, while not putting so much air through the system
that the efficiency is low. I should also warn that we generally
believe that radiative transfer is more important than convection when
dealing with charcoal - so you want the pot pretty close to the
charcoal.
Best of luck. Ron
(a EE, not an ME or
ChE)

From dstill at epud.net Wed Sep 5 02:13:01 2001
From: dstill at epud.net (Dean Still)
Date: Tue Aug 31 21:37:00 2004
Subject: Lanny's Stove Project
Message-ID: <001901c135f1$0aaa2dc0$3715210c@default>

Dear Lanny,

Great to see you working on the Rocket type stove ideas.
Perhaps you'd like to get in touch with Larry Winiarski the designer of the
Rocket stove design principles. There are 20 years of Rocket prototypes that
have explored a lot of possibilities of stove configurations, etc. A lot of
Rocket designs have either sidefeed or downfeed fuel magazines or angles in
between. Larry has spent a lot of time on burning sawdust, rice hulls, etc,
using various mechanisms. The most successful looks like a ladder under a
hopper.His phone number is 541 753 4921

I'm sure that you'll find great innovations! Please keep us
informed. Maybe you'd like Capturing Heat One and Two, booklets that go through
some of the variations of Rockets?

Best,

Dean Still
<BLOCKQUOTE
style="BORDER-LEFT: #000000 solid 2px; MARGIN-LEFT: 5px; PADDING-LEFT: 5px">

From lanny at roman.net Thu Sep 6 06:30:24 2001
From: lanny at roman.net (Lanny Henson)
Date: Tue Aug 31 21:37:00 2004
Subject: Lanny's Stove Project
In-Reply-To: <001901c135f1$0aaa2dc0$3715210c@default>
Message-ID: <008601c136be$50dafea0$10ba3cd0@default>

Dean,
It sounds like I need to catch up on some
information. Where can I find Capturing Heat One and two?
Lanny
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px; PADDING-LEFT: 5px; PADDING-RIGHT: 0px">
----- Original Message -----
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black">From:
Dean Still
To: <A href="mailto:lanny@roman.net"
title=lanny@roman.net>Lanny Henson ; <A href="mailto:stoves@crest.org"
title=stoves@crest.org>stoves@crest.org
Sent: Wednesday, September 05, 2001 5:56
AM
Subject: Re: Lanny's Stove Project

Dear Lanny,

Great to see you working on the Rocket type stove ideas.
Perhaps you'd like to get in touch with Larry Winiarski the designer of the
Rocket stove design principles. There are 20 years of Rocket prototypes that
have explored a lot of possibilities of stove configurations, etc. A lot of
Rocket designs have either sidefeed or downfeed fuel magazines or angles in
between. Larry has spent a lot of time on burning sawdust, rice hulls, etc,
using various mechanisms. The most successful looks like a ladder under a
hopper.His phone number is 541 753 4921

I'm sure that you'll find great innovations! Please keep us
informed. Maybe you'd like Capturing Heat One and Two, booklets that go
through some of the variations of Rockets?

Best,

Dean Still
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; MARGIN-LEFT: 5px; PADDING-LEFT: 5px">

From psanders at ilstu.edu Thu Sep 6 14:34:00 2001
From: psanders at ilstu.edu (Paul S. Anderson)
Date: Tue Aug 31 21:37:01 2004
Subject: Briquettes materials
Message-ID: <4.3.1.2.20010906123031.00b53f00@mail.ilstu.edu>

Apolinario in Mozambique, (and others on the stoves list)

In my humble opinion, it appears to me that not very much is known about
the different biomass materials for briquettes.

In general, the VERY FEW people making briquettes are using whatever
materials are available and seem to burn well. There is not much "true
research" about these materials, in terms of length of burn, heat
generated, pollution, costs (both money and time), etc.

Yes, Richard Stanley has the most information, but as he has written, his
focus is on applicable impact to assist the needy people, and less on the
"engineering issues" of the briquettes and how they burn or how they can be
burned better.

And there needs to be a balance between the "beneficial applications" and
the "scientific documentation" issues.

For example, we might learn that type X of sawdust yields Y% increase in
heat at the expense of Z increase in air pollution. Great. But for the
hungry worker's family in the Andes mountains or the Zambezi floodplain,
the questions are about having "any sawdust" available and about warmth for
a cold night in the Andes or being too hot if indoors along the
Zambezi. Pollution? Minor issue compared to eating and warmth.

I just wonder if such discussions about applications and research are
covered in the BioMass conferences, like what is happening in a week or two
in Orlando? (Comments from anyone who has been to those conferences
before, please.)

All of the above comments (if reasonably accurate) means three things (and
maybe more?):

1. A major funder like Shell Foundation should consider bringing the two
sides (scientific research and applications for the benefit of the poor)
closer together for mutual benefit. I hope that someone will latch onto
this idea and get it to the right people.

2. The work that is being done in Mozambique and elsewhere about
briquettes, which I thought to be extremely basic, is in fact increasingly
important and essential. But our focus in MZ is on the applications side,
that is, on finding SOMETHING that can work reasonably well and then
propagating that something to benefit more people who have similar raw
materials and conditions. I can think of dozens of variations of
briquettes and how to burn them, which, when placed side by side in a Third
World location, could be closely observed and thereby lead to results that
could be immediately applied to that area. This would take some money and
effort, but at only a fraction of the cost of doing it at my or any other
university or research lab.

3. Personal opinion: In general, scientific research could easily gobble
up the lion's share of the available funding "in the name of generating
knowledge" while the applications side (specifically directed toward those
with minimal education and almost no capital) will only have the bones to
pick in terms of financial assistance to get even the most basic
improvements delivered to them (explained to them) in meaningful ways.

As Richard has pointed out in earlier messages, the "local people" (read
that as "the poor and semi-literate underemployed person in the Developing
World") have a "feel" for the materials, the processes, the uses of the
briquettes (or of other materials) that is far more appropriate than a
scientific instrument that measures dampness, or ppm of particles, or
calories (joules), etc. We need more work with the local implementations.

I still say we need progress and expansion of BOTH science and appropriate
application, but let's make sure that applications are not second fiddle to
our thirst for knowledge.

(Sorry if I upset anyone. But I am amazed at how little we seem to know
about such an important and basic topic and about how to get advances
delivered to the needy.)

Sincerely,

Paul
Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:stoves@crest.org>
List-Help: <mailto:stoves-help@crest.org>
List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
List-Subscribe: <mailto:stoves-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From crispin at newdawn.sz Thu Sep 6 15:56:50 2001
From: crispin at newdawn.sz (Crispin)
Date: Tue Aug 31 21:37:01 2004
Subject: Hello from a new subscriber
Message-ID: <005301c136a8$f962ec60$55e80fc4@home>

Dear Stovers

I have been introduced to this list by Doug Banks in South
Afica. Thanks Doug for the pointer!

A brief introduction:

Name: Crispin Pemberton-PigottPosition:
ManagerNew Dawn Engineering (Pty) Ltd.Activities: Manufacture of
labour-based production equipment for ruralareas.

Other Activities:
Vice-Chair, Renewable Energy Association of Swaziland
(REASWA)
Member - Swaziland National Biomass Energy Team
Member - National Energy Policy drafting committee (green
paper)Participant - Climate Technology Initiative Projects group (CTIP)
within SADC

Interests:
Improving burning efficiency of small stoves,
Improving the use of available biomass to prevent
environmental problems
Mass producing biofuel briquettes from wasted
resources
Saving 1 millions tons of fuelwood by introducing better stove
technology to the region.
Replacing coal with biomass fuel for domestic cooking and
space heating

Relevant products which may stimulate subscriber
interest:(1) Biomass fired fuel efficient stoves for single and multiple
potsfeaturing primary and secondary combustion with preheated secondary
airinjection.
(2) Paper bound biomass briquettes and labour intensive
briquette making equipment
Web site <A
href="http://www.newdawn-engineering.com">www.newdawn-engineering.com
Location: Matsapha Industrial Park, Swaziland, South Eastern
Africa next toMoçambique about 400 km east of Johannesburg.

Best regards to all
Crispin

From psanders at ilstu.edu Thu Sep 6 17:58:56 2001
From: psanders at ilstu.edu (Paul S. Anderson)
Date: Tue Aug 31 21:37:01 2004
Subject: Briquettes materials
In-Reply-To: <4.3.1.2.20010906123031.00b53f00@mail.ilstu.edu>
Message-ID: <4.3.1.2.20010906165603.01a3eaa0@mail.ilstu.edu>

Greetings to John, and copy to Stovers,

No you did not send info earlier.

I visited your website. Nice product. But manufacturing is beyond my
focus for Mozambique.

The hole in the center is very interesting.

I wonder if your logs might serve as a "standard" that is more constant and
measurable than other normal logs, PLUS you already have a hole
!!!!!!!!!!!!!!!! Would you be interested in that? That would mean a
donation of some of your logs to people who would help determine if it
could serve as a standard.

Question to all: Do we have a "standard" or even need one????

Paul

At 11:48 AM 9/6/01 -0700, you wrote:
>Hi Paul,
>Did I ever send you info on th SHIMADA /HeatLog?
>regards
>John Olsen.
>President.
>Cree Industries.
>200 - 100 Park Royal South,
>West Vancouver,
>British Columbia,
>V7T 1A2
>CANADA
>tel/fax (604) 533 4950
>http://sites.netscape.net/hempcree/creeindustries
>cree@dowco.com
> SIB KIS
>(See It Big, Keep It Simple)

Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:stoves@crest.org>
List-Help: <mailto:stoves-help@crest.org>
List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
List-Subscribe: <mailto:stoves-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From tami.bond at noaa.gov Thu Sep 6 19:12:00 2001
From: tami.bond at noaa.gov (Tami Bond)
Date: Tue Aug 31 21:37:01 2004
Subject: Briquettes with holes
Message-ID: <3B980170.9D318959@noaa.gov>

Stovers,

Paul writes:

> 2. In my humble opinion, although this technology seems to work for China,
> I feel it is not likely to be of much application in Africa, Latin America,
> or southern Asia, at least not in the near or mid-future.

Is that because of cost?

I agree that factory-generated briquettes are not as helpful to
improving the lifestyles of many in poorer regions. It is a big
enterprise, too big for a small village. There are state-run and
privately-run briquette factories-- but they are factories, not
"cottage" industries.

Rural people in China do coal briquetting on their own because it
results in more stable and predictable combustion than burning raw coal.
I hope to get a chance to look at those village-made briquettes, too. It
is also true that coal is local to China and may not be relevant to
other areas. In rural areas, it is usually used when the region is
deforested and the people have access to near-surface coal seams. Coal
is not "sustainable" or "renewable". On a personal level, I struggle
with that issue. Is it better to get people off coal-- which would
require a major intervention? Or to promote an intermediate
intervention, such as briquetting, for health reasons?

I would guess that long-burning briquettes are more useful in cold
regions because the household needs the heat, anyway.

I think the briquette issue, coal OR biomass briquettes, is interesting
because of what we can learn about reducing emissions through various
steps of briquetting process. If there is a relationship between binder
and volatile matter, that knowledge might be applicable to more than one
fuel.

Tami

-
Stoves List Archives and Website:
http://www.crest.org/discussion/stoves/current/
http://www.ikweb.com/enuff/public_html/Stoves.html

Stoves List Moderators:
Ron Larson, ronallarson@qwest.net
Alex English, english@adan.kingston.net
Elsen L. Karstad, elk@wananchi.com www.chardust.com

List-Post: <mailto:stoves@crest.org>
List-Help: <mailto:stoves-help@crest.org>
List-Unsubscribe: <mailto:stoves-unsubscribe@crest.org>
List-Subscribe: <mailto:stoves-subscribe@crest.org>

For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From rstanley at legacyfound.org Thu Sep 6 19:13:53 2001
From: rstanley at legacyfound.org (Richard Stanley)
Date: Tue Aug 31 21:37:01 2004
Subject: Briquettes materials
In-Reply-To: <4.3.1.2.20010906123031.00b53f00@mail.ilstu.edu>
Message-ID: <3B980266.6AC96639@legacyfound.org>

Paul,
I wish we knew each other 7 years ago when this all began in earnest.
The heat cpontent of thevarious mixtures of the briquettes are being studied
in Peru at San Antonio University in Cusco. The heat contect
and pollutants have been studied at our own Southern Oregon University
here in Ashland Oregon. In fact our paper on the latter is to be presented
at the Fifth Biomass conference.
While I and one of our Kenyan counterpart organisations are developing
improved presses, the need remains for the key link into the mass community,
if we are to do any good. I concur about ther need for expanded scientific
research but it should be stated that in fairness , this is not the weak
link: Materials research will go on forever but every maize crop per every
locality and time of harvest and microclimate will give different results.
Chala de maize at 11,200 ft in Mosocclaycta does nto yield the same kind
of heat as the chafu za mahindi in Kangemi Kenya. And even if it did the
cooking application and elevation differences are so substantial as to
warrant an entirely separate investigation.
One can make quite a research project just about his aspect but
in the end, it rests with the indigineous citisen to determine and fine
tune the trechnology for their own circumstances. There is a certain beauty
in that fact. They have to be engaged to make it work for their own area.
Still I do not discount the need for improvements in the production
technologies and applicaiton of the briquettes. There is always a new twist
to be explored and the need is outrageously huge and increasing--and after
seven years with it we are only on the tip of the iceberg.
As concerns your kind effort to get me into Mozambique, as part of some
other trip, thanks but I should remind you that the trip itself has to
be paid for. This is not part of other work ofor us. It is one of our main
efforts.
Richard Stanley

From cree at dowco.com Thu Sep 6 21:27:04 2001
From: cree at dowco.com (John Olsen)
Date: Tue Aug 31 21:37:01 2004
Subject: Fw: Briquettes materials
Message-ID: <006601c1373b$d3481800$678457d1@olsen>

Paul,Certainly we would supply "Heatlogs" for
research. As we open more and more factories, on Native Reserves,
across North America, using theabundant sawdust and biomass, a consistent
log in size weight and specs, is always
available. regards John Olsen
Cree Industries> I wonder if your logs
might serve as a "standard" that is more constant andmeasurable than
other normal logs, PLUS you already have a hole!!!!!!!!!!!!!!!!
Would you be interested in that? That would mean adonation of some of
your logs to people who would help determine if itcould serve as a
standard.

From costaeec at kcnet.com Thu Sep 6 23:18:27 2001
From: costaeec at kcnet.com (James Dunham)
Date: Tue Aug 31 21:37:01 2004
Subject: Briquettes materials
In-Reply-To: <4.3.1.2.20010906123031.00b53f00@mail.ilstu.edu>
Message-ID: <CEEJJCPBKMDPHAMPLNGPAEFFCAAA.costaeec@kcnet.com>

Paul & all;

I have not responded to this topic before, but it seems time to offer some
history.

The sad fact is that much is known about biomass densification, but the
reality of economics often prevents the utilization of this knowledge in
situations or areas where there is no profit potential.

We have been involved in biomass briquetting for decades, using virtually
every imaginable feedstock, in all areas of the world. From pellets to 125mm
briquettes; low density to rock hard; solid pucks to center hole to
multi-hole. The technology exists & is in wide use. It's all been done and
there are volumes of data to define the characteristics of each variation.

We get many inquiries from around the globe, and many are from developing
countries. I am ashamed to admit that we have yet to install a modern,
automated briquetting system in these areas; even when they desperately need
it and have access to funds.

The attitude seems to be that it is too costly or they would rather use
manual labor to keep the people busy. Perhaps that is true or perhaps they
are simply not ready to accept modern technology or a project which reeks of
'capitalism'. I am not qualified to determine that, but it seems primitive
to admit a serious problem exists, yet refuse to accept the proven
solutions.

Many areas simply don't have the materials or demand to justify mechanical
systems, but with a little creativity in calculating transportation costs
(or simply the difficulty) of bulk materials versus densified materials the
equations look quite different.

We can't help with methods of hand making small quantities of briquettes,
but I think it might be quite shocking to some to see how close your
situations are to justifying modern automation.

BOTTON LINE: With certain supply and demand conditions in place, you can
provide cheap cooking and heating fuel AND make a profit!

Glad to help, if we can.

Jim Dunham, CEO
Enviro-Energy Corp.
816.452.6663

lto:psanders@ilstu.edu]
Sent: Thursday, September 06, 2001 1:38 PM
To: Apolinario J Malawene; stoves@crest.org
Cc: Bob and Karla Weldon; Ed Francis; Tsamba--Alberto Julio;
clucas33@yahoo.com; clucas@zebra.uem.mz
Subject: Briquettes materials