BioEnergy Lists: Improved Biomass Cooking Stoves

From larcon at sni.net Sun Mar 1 07:43:19 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:49 2004
Subject: Forwarded (#2):Judkovich on Russian charcoaling
Message-ID: <v01540b06b11d2633de88@[204.133.251.7]>

Stovers - the following came in a few days ago from Dr. Jury Judkevich
following my earlier forwarding. I have edited it slightly. Dr. Judkevich
has also sent a photograph which will hopefully soon be set up by Alex
English. Some new comments and questions by me are also interspersed. Ron

 

Dear Dr. Larson!
Our design is the brick furnace. Into this furnace insert cylinders from a
metal pipe. The top of the cylinder is closed. The bottom is a lattice
(grid-iron). The grid-iron can be removed if to turn on 45 degrees. At
first step the cylinder overturn, remove a grid-iron and fill wood (fire
wood or small-sized pieces of a tree another chips). A grid-iron put on a
place and the cylinder overturn by a hole downwards. In the upper cover of
the furnace there are holes. In them put cylinders. Holes a little and the
cylinders put in a miscellany time.

(RWL): I think I have a picture (that will be improved when I see your
photograph), but your last sentence is not clear. Does this mean that the
cylinders do not fit tightly into the oven top - and they are not all
inserted at the same time? Are there closures for these holes when the
cylinders are not in place? How many total cylinders and how many in use
at any one time? What diameters and lengths of cylinders have you tried
and do you prefer? This has some of the features of what we have called a
"Grover" stove, in that the pyrolysis gases exit at the bottom and then
ignite and further heat the fuel in a surrounding torus (with no air
meeting the wood source directly)..

When in one cylinder the fuel dries, in the friend the gas is already
selected (allocated).

(RWL) Does the word "friend" perhaps mean "a neighboring cylinder"
and "selected/allocated" perhaps mean "consumed/used up" (and the cylinder
ready to be replaced)?.

The gas burns and gives warmly. If the initial
humidity of wood is less than 50 %, the fuel is not necessary. The good
coal (87 % of nonvolatile carbon) is received. Such coal burns without a
smoke in any opened furnace. I have named this installation "Polykor". In
this name the names of my favourite teachers are saved which already have
died many years ago. It is the professor Pomerancev, professor Liverovsky,
professor Korotov. They have learned me to everything, that I know in the
field of wood coal and there were good people. I and my comrades have
received the message, that to us the patent to this design is produced. But
patent has not come yet. We have interest to commercial use of this
process. In Russia there is a corporation, which financed activity and
prototype installation. We would like to receive a contact to such
corporation not in Russia. We now have economic difficulties and the
activity goes slowly, and the life is short. But I am off-the shelf without
payment to help the one who is poorer than us. But I may to give only
advice. There is no money to go anywhere.

(RWL): This seems to be mostly true for our list members
throughout the stoves (and probably charcoaling) community. However, some
few funders are on this list and perhaps some will now be able to contact
you.

For our furnace are not necessary
neither electricity, nor vapours, water. Is necessary only the lift, but
also it can be manual.

Yours faithfully J.Judkevitch

(RWL): Dr. Jury - I think this is a very interesting design that I
have not seen nor heard of before. It is very valuable to this list that
you are doing this with simple methods.
As you may know, we have also been talking about turning sawdust to
charcoal. Do you believe this furnace/cylinder system might also work for
sawdust and have you ever tried that?
Have you ever been able to make measurements of the exhaust gases?
Do you believe this charcoal-maker is quite clean - no smoke?
This would seem possibly to have application where you might be
able to use the waste heat for some productive application such as a kiln,
bakery etc. Have you looked into this?

I also should note for all other "stoves" list readers that your
message contained a second version of the above which seemed identical
except for two lines related to "... installation "Polykor" :

"..the professor Pomerancev, professor Liverovsky, professor Korotov.." and

"..the professor •¦Õ‰"¡‘ˆ‰×, professor ϊ׉"¦×"ÀŠ , professor Φ"¦'¦×.".

As a former Professor, I think this was a very nice naming and I
would like to hear more about their work if it is appropriate for this list
(and especially if anything is available in English).
But I also wonder about the very strange symbols (which may come
through in some other form on other persons' receipt of this message, I am
afraid - so others may not know what I am talking about). In your word
processors, did you start with a Russian keyboard and alphabet before going
through an electronic translator and being sent over the Internet? Should
I have sent this second message as well? The only other change I found was
where you said:

"There is no money to go where ‘Š¬'Ÿÿ. For our furnace are not necessary
neither electricity, nor pairs(vapours,couples), water. Is necessary only
'‰Ãÿ‰", but also it(he) can be manual."

This must explain the word "pair" above, but perhaps you can still
explain more on it and the (I think only) new word "couples".

Again,Jury, I apologize in my delay in getting this off. I had a
busy week. You obviously are doing good original work. This was a very
valuable contribution and I look forward to also seeing the photograph
(through Alex).

Regards, Ron

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

 

 

From english at adan.kingston.net Tue Mar 3 19:12:20 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:49 2004
Subject: Web page update.
Message-ID: <199803040018.TAA23517@adan.kingston.net>

Dear Stovers,
Dr. Jury Judkevitch's stove concept can be viewed now. Just check
under the NEW heading at the webpage address below.

Alex

______________
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Web Site http://www1.kingston.net/~english/Stoves.html

 

From elk at arcc.or.ke Wed Mar 4 06:52:26 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:35:49 2004
Subject: The Grover Modification - Carbonising Sawdust
Message-ID: <v01510101b12318cf41df@[199.2.222.153]>

After some off-line communication with Ronal a new approach is made:

Just came in in a cloud of smoke from my most recent attempt at carbonising
sawdust. Two metal tubes with a fire in the center one and sawdust passed
between the two. Volatiles (smoke) from the carbonising sawdust is drawn
from perforations at the bottom the inner tube and flared along with some
burning fuel wood in this inner (chimney) tube. The inner tube has some
steel rods welded in a spiral down the outside, and can be rotated by hand
within the outer tube, imparting an auger-type downward force on the
sawdust. A restriction at the lower end keeps the sawdust-charcoal from
spilling out freely. It works surprisingly well, with a very rapid
through-put of sawdust considering the size of the unit at roughly 70cm
tall by 25 cm outer diam., but there are some loading and emptying quirks
to be worked out, as well as some flue and venting considerations to be
made.. As a demonstration of the principal though, I'd say it's a success!

elk

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
______________________________

 

 

From larcon at sni.net Wed Mar 4 10:56:25 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:49 2004
Subject: Forwarded (#3):Judkovich on Russian charcoaling
Message-ID: <v01540b02b1225082ea86@[204.133.251.35]>

(RWL): Stovers - the following came in today from Dr. Jury Judkevich
responding to my earlier forwarding of message #2 from Dr. Jury.

(J.J.-1)I thank you for the fact that you edit mine very bad English. My
electron interpreter that requires editing after translation, but I do it
poorly. Excuse me.

Figure in my file this remark to a delineation in a network. The figure of
the furnace I did not transmit. I shall do it, when Alex will manage to
read the first figure. I have sent a figure in a new format. There can be
it will be clear. It is necessary to inform me what version Word for Windows
stand on your machine. Then I can transmit the necessary format.

(RWL-1): Dr. Jury - I know that you are now communicating directly with
Alex. I believe he can put both figures and text on his Web site and it
would be best for us all to rely on Alex' skills to make the necessary
electronic adjustments for both figures and text.

(J.J.-2 background question):
> (RWL): I think I have a picture (that will be improved when I
see your
> photograph), but your last sentence is not clear. Does this mean that
the
> cylinders do not fit tightly into the oven top - and they are not all
> inserted at the same time? Are there closures for these holes when the
> cylinders are not in place? How many total cylinders and how many in use
> at any one time? What diameters and lengths of cylinders have you tried
> and do you prefer? This has some of the features of what we have called
a
> "Grover" stove, in that the pyrolysis gases exit at the bottom and then
> ignite and further heat the fuel in a surrounding torus (with no air
> meeting the wood source directly)..
>
> When in one cylinder the fuel dries, in the friend the gas is already
> selected (allocated).

(J.J.-2)
If the cylinder does not stand in a hole, the hole is closed by a cover. A
cover goes on each hole sideways.
If the activity is made correctly, the empty place should not be long times.
The cylinder with fire wood (spare)is prepared separately and put in place
as soon as a place is released.
The number of cylinders is 3 times more than the number of holes. The part of
cylinders stand with coal in supports. The coal cools down before
outswapping. In other cylinders load fire wood.
3.. 5 cylinders stand in the furnace. The diameter of the cylinders is 1 to
1.5 m;
their length is 2 to 3 m.

(RWL-2) Both the cylinder diameter and length are appreciably larger than
I had imagined. How long does each cylinder stay in place?

(J.J-3 background question)
> (RWL) Does the word "friend" perhaps mean "a neighboring
cylinder"
> and "selected/allocated" perhaps mean "consumed/used up" (and the
cylinder
> ready to be replaced)?.

(J.J-3) Yes! Pardon me my English!

(RWL-3): I think we are communicating pretty well. Thank you for the
confirmation.

(J.J.-4 background question):
> (RWL): This seems to be mostly true for our list members
> throughout the stoves (and probably charcoaling) community. However,
some
> few funders are on this list and perhaps some will now be able to contact
> you.
>
<snip>
> (RWL): Dr. Jury - I think this is a very interesting design that
I
> have not seen nor heard of before. It is very valuable to this list that
> you are doing this with simple methods.
> As you may know, we have also been talking about turning sawdust
to
> charcoal. Do you believe this furnace/cylinder system might also work
for
> sawdust and have you ever tried that?
> Have you ever been able to make measurements of the exhaust
gases?
> Do you believe this charcoal-maker is quite clean - no smoke?
> This would seem possibly to have application where you might be
> able to use the waste heat for some productive application such as a
kiln,
> bakery etc. Have you looked into this?
>

(J.J.-4):
We made coal from pellet. These pellet (h = 20mm; d = 5mm) made of sawdust
on technology similar that makes) Dr Chai Yoke Loong. The coal was received
strong. The contents of nonvolatile carbon 80%. It was only experiment in
laboratory. At a plant we did not make coal of sawdust. There we make coal
of fire wood. All gases burn down inside stover and in an air do not act.

(J.J.-5 background question from RWL asking to explain the difference between):
> I also should note for all other "stoves" list readers that your
> message contained a second version of the above which seemed identical
> except for two lines related to "... installation "Polykor" :
>
> "..the professor Pomerancev, professor Liverovsky, professor Korotov.."
and
> "..the professor •¦Õ‰"¡‘ˆ‰×, professor ϊ׉"¦×"ÀŠ , professor Φ"¦'¦×.".

(J.J.-5):
The repetition of the text is my error. I ask to excuse.
It was the draft copy. I have corrected names in pure version, and in a
draft copy they have remained in a cyrillic. Pardon me.

(RWL-5): Thank you. I am surprised that the above is recognized as cyrillic.

(J.J.-6, background question from RWL):
> As a former Professor, I think this was a very nice naming and I
> would like to hear more about their work if it is appropriate for this
> list (and especially if anything is available in English).

(J.J.-6):
I know their papers and books only in Russian. It may be they are available in
English. If I shall find out, I shall write to you.

a. The professor Pomerancev in 1957 developed a new design of a stove
for scraps (bark, sawdust, scraps). Burned down even bark from machine
tools wet bark down of wood. This stove is working at cellulose plants of Russia
today.

b. The professor Liverovsky has developed many interesting technologies.
During 2 world wars the soldiers used a little stove of his using wood coal.
The stove worked without smoke and stayed lit for 3 to 4 hours. For 50 years he
has created fluids from the pyrolisis products of wood. The fluid does not
contain a cancer-causing substance. The fishes made with this fluid are
very tasty and are well stored. It is possible smoked in the home microwave
furnace:
put a crude fish in fluid and to prepare.

c. The professor Korotov taught the students to do nothing without a
precise calculation (heat transfer, mass exchange, hydraulics). His
developments always began to work without alterations.

I thank for the help and kind wishes
J.Judkevitch

(RWL): Dr. Jury - Thank you also. I hope we can learn more about English
translations of your work and that of the three Professors.
I again did a little editing and hope that I did so correctly. I
am still interested in your use of the English words "pairs" and "couples"
in your message #2. Could you please explain these words?

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

 

 

From larcon at sni.net Thu Mar 5 17:49:19 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:49 2004
Subject: Forwarded (#4):Judkovich on Russian charcoaling
Message-ID: <v01540b02b124cab940b6@[204.133.251.21]>

(RWL): Stovers. One more communication from Dr. Jury.In message #3, I said:

> (RWL background #1):

> I am still interested in your use of the English words "pairs" and
>"couples" in your message #2. Could you please explain these words?

(J.J. - #1):
Thank you for translation into English. I also thank you for the
help in a contact with stovers.
The words ("pairs" and "couples"), which I probably unsuccessfully have
applied, should mean a mix of gas, vapours and drops. This mix will be
derived in the transformation of wood into charcoal.

(RWL- #1): Thank you. Your description is clear.

(background #2 by RWL)
> I hope we can learn more about English
> translations of your work and that of the three Professors.

(J.J.-2)
I send you a basic kind of the cartridge and furnace "Polikor".

Sincerely J.Judkevitch

(RWL-2) Stovers, this will go again to Alex. I look forward to seeing this.

Regards Ron

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

 

 

From larcon at sni.net Thu Mar 5 17:49:33 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:49 2004
Subject: The Grover Modification - Carbonising Sawdust
Message-ID: <v01540b00b124def62510@[204.133.251.21]>

Elsen -
This is very good news. You obviously are the place to go to to try
new ideas. A few questions:

1. What are the tube diameters and lengths? Was this a model or a working
scale unit?
2. Approximately what is the transit time or throughput in kG/hr?
3. Is the geometry such that the flared gases might be used in some way?
4. Was the central wood supply only needed to start the process?
5. When can we expect a photo through Alex?

Congratulations. Ron

>After some off-line communication with Ronal a new approach is made:
>
>Just came in in a cloud of smoke from my most recent attempt at carbonising
>sawdust. Two metal tubes with a fire in the center one and sawdust passed
>between the two. Volatiles (smoke) from the carbonising sawdust is drawn
>from perforations at the bottom the inner tube and flared along with some
>burning fuel wood in this inner (chimney) tube. The inner tube has some
>steel rods welded in a spiral down the outside, and can be rotated by hand
>within the outer tube, imparting an auger-type downward force on the
>sawdust. A restriction at the lower end keeps the sawdust-charcoal from
>spilling out freely. It works surprisingly well, with a very rapid
>through-put of sawdust considering the size of the unit at roughly 70cm
>tall by 25 cm outer diam., but there are some loading and emptying quirks
>to be worked out, as well as some flue and venting considerations to be
>made.. As a demonstration of the principal though, I'd say it's a success!
>

PS- personal to Elsen - This was intended to go to the full list a few days
ago - sorry you get two copies. RWL

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

 

 

From elk at arcc.or.ke Fri Mar 6 06:03:36 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:35:49 2004
Subject: The Grover Modification- Carbonising Sawdust
Message-ID: <v01510100b125a85e81b9@[199.2.222.132]>

In response to Ronal's guestions:

1) The tube diameter and lengths are as follows-
Inner tube 54 cm high 16 cm diam.
Outer tube 61 cm high and 21 cm diam.

Both tubes are flush at the top. The shorter inner tube is held on cross
bracing 7 cm above the bottom of the outer grill. It is centered within the
outer tube with vertical pegs on the cross bracing and horizontal pegs
extending inward from the outer tube at the top. The space at the bottom
between inner aond outer tubes allows carbonised material to collect within
the base of the unit. This 7 cm high section at the base of the outer tube
also has air holes drilled to allow fresh air into the interior and on up
the inner tube.
A grill is located within the inner tube 15 cm from the bottom of the outer
tube and 8 cm from the bottom of the shorter inner tube. This 8 cm section
between the bottom of the inner tube and the grill is perforated heavily to
allow volatiles (white smoke produced by carbonising sawdust) to escape
below the grill allowing this gas to be flared by the wood fuel burning on
the grill within the inner tube (chinmey).

Oh yes- there is a restriction at the bottom of the inner tube between the
inner and outer tube walls to 1 cm. This allows carbonised sawdust to
bridge and stops material from simple pouring right through the entire
unit. Rotating the inner tube breaks the bridge and carbonised sawdust
falls into the bottom cavity.

2) Transit time seems short- I'd estimate a mere 3 minutes. My sawdust was
pretty old & hence dry (10 to 12% moisture?). Throughput can only be
guessed at at this time due to problems with loading and emptying (I'll
explain that later), but I'd say that if the unit held 4 kg of air-dry
sawdust, and transited at 3 min = 80 kg/hr. I don't know how scaling this
up or down would affect the function. The next version will be made to
roughly the same scale.

3) The flared gasses are used to help drive the pyrolysis by heating the
inner tube (chimney/combustion chamber) along with the wood fire.

4) The central wood fire starts the process and acts as a 'spark plug' to
maintain combustion of the pyrolysis gasses entering the inner tube below
the grill.

5) Unless strictly instructed, I'll hold off on a photo to Alex for the Web
site until the next version is ready for trials in a week or so. Function
should be more graphically obvious with MK II.

The problems alluded to above were encountered in loading sawdust, as this
was a sloppy procedure allowing for much spillage due to both inner and
outer tubes being flush with eachother at the same height above ground.
Hand feeding sawdust into the 2.5 cm gap between inner and outer tubes
while a (ouch) hot fire burns within was not a precise manouver and much
sawdust spilled both into the chimney and onto the ground where it
invariably was mixed into the finished product.

Collecting the carbonised sawdust was also a problem necessitating the
entire unit being picked up and repositioned. If too much material was
allowed ro collect in the base the air inlet holes were blocked and flaring
ceased.

Also, my choice of 3mm diam perforated steel plate for the grill was not
good, as ash from the wood fire blocked these holes. This resulted in
flaring within the base below the grill as evidenced by flames shooting out
of the air inlet holes. Airflow must've reversed then. This also burnt some
of the collected carbonised sawdust to white ash.

The 4 pieces of quarter inch diam. round bar welded to the outside of the
inner tube each make a 2/3 circumnavigation of the tube between top and
bottom attachment points. This works well as an auger when the inner tube
is rotated within the outer by means of horizontally placed bar 20 cm above
the top of the tubes and connected directly to the inner tube by round-bar.

I plan to resolve most, if not all of these problems with the MK II
version. Maybe I was a bit hasty to report on this initial trial- I plead
guilty to letting my enthusiasm get the better of me, and apologise for the
confusing-at-first-reading description here.

elk

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
______________________________

 

 

From english at adan.kingston.net Fri Mar 6 18:44:10 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:49 2004
Subject: Polykor Furnace
Message-ID: <199803062350.SAA23996@adan.kingston.net>

Dear Stovers,
Have a look at a drawing of Dr. Jury's Polykor furnace. The link has
just been added to the NEW section on the webpage listed below.

Alex

______________
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Web Site http://www1.kingston.net/~english/Stoves.html

 

From english at adan.kingston.net Sat Mar 7 22:39:59 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:49 2004
Subject: Polykor Questions
Message-ID: <199803080346.WAA32110@adan.kingston.net>

Dear Dr. Jury,
I have some questions about the Polykor furnace.

Does all the wood in the cylinder dry out before pyrolysis begins at
the bottom and moves up?

I am thinking that the wood is heated efficiently by steam evolving
from the wood at the bottom of the cylinder, next to a start up fire
in the brick furnace below. As the portions of the wood reach 100
degrees C more steam is produced and exits the bottom of the
cylinder into the furnace. The steam keeps the temperature below
that for pyrolysis until all the wood, to its core, has reached 100
degrees C. At this point most of the moisture in the wood has been
driven off. ( This is much like the " Airless" or steam drying system
that was mentioned on the Gasification list a few weeks ago.)
Then the temperature can rise, and pyrolysis of the wood begins.

Is this correct?

Does the wood react without any air?

Is a small wood fire maintained in the furnace to reliably ignite
the gasses which flow down into the furnace from the pyrolysing
cylinders of wood?

I hope this translates adequately, Alex

______________
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Web Site http://www1.kingston.net/~english/Stoves.html

 

From REEDTB at compuserve.com Sun Mar 8 16:19:03 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:35:49 2004
Subject: Biomass Chemistry Tutorial
Message-ID: <199803081624_MC2-35FF-E13D@compuserve.com>

Dear Bioenergy and Stoves:

Have you ever wished to make mass or energy calculations on biomass
reactions and been frustrated by the fact that "biomass" has no exact
composition? A tutorial (for Volume II of "A Survey of Biomass
Gasification" shows how such calculations can be made).

I am publishing this in the GASIFICATION node in hopes of getting either
questions, criticisms or suggestions before the text appears finally in the
book.

Yours truly, TOM REED - GASIFICATION

 

 

From larcon at sni.net Mon Mar 9 12:38:21 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:49 2004
Subject: Forwarded: A Query on Wicks
Message-ID: <v01540b00b12918e7459e@[204.133.251.27]>

Dear Tom Duke and associates:
I am looking for a wick or punk that is similar in charteristics to
a cigarette: burns for 5-10 minutes, continues burning once lit even if
left on ground, approximate same size and and length.
Do you know of such a product?
Sincerely,
Millard Christner <millard@equitygroup.com>

 

 

From elk at arcc.or.ke Wed Mar 11 02:55:53 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:35:49 2004
Subject: Living Dangerously - Carbonising Sawdust
Message-ID: <v01510100b12c1b007b92@[199.2.222.130]>

Nearly lost my eybrows & shortened my hair significantly during the first
'Grover mod. MkII' trial yesterday.

This 'blast furnace' needs a governor! A mini Mt. Vesuvius of a volcano
erupted out through the feedstock sawdust surrounding the
chimney/combustion chamber in a jet of pure white smoke. I was standing
uncomfortably close when ignited in a 2 meter tall flare filled with
sparkling bits of igniting charcoal powder.

Due to the pressures within the pyrolysis jacket surrounding the
chimney/combustion chamber, the aformentioed problem occurs occasionally,
as well as quite a bit of carbonised sawdust being blown through the
perforations under the grill. The larger particles drop down, but the
smaller ones go up & are burnt along with flared gasses, causing a
significant reduction in recovered carbonised sawdust.

Looking down the chimney (this is done very quickly & with great caution
due to the heat), one see what appears to be the inside of a regular boiler
furnace, with flaring gasses entering the chimney under pressure and
creating a strong flue draft. The grill is heated to a bright orange
colour. Very little (if any) wood need be added once the flaring commences.

Trials continue today. I think this may be a step forward, but I'm
intimidated by this machine. Have I created a monster? I need to learn how
to control the rate of pyrolysis in order to reduce the dangers and to
increase end product recovery.

This "stove" may have some other applications though...?

I'll get a picture to Alex soon.

Regards;

elk

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
______________________________

 

 

From english at adan.kingston.net Thu Mar 12 18:23:03 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:49 2004
Subject: Elsen's Pictures
Message-ID: <199803122329.SAA03879@adan.kingston.net>

Dear Stovers,
Check out Elsen's sawdust volcano, under the NEW, at the site below.

Alex

 

 

From english at adan.kingston.net Thu Mar 12 18:44:53 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:50 2004
Subject: (Fwd) Elsen's Pictures
Message-ID: <199803122351.SAA06376@adan.kingston.net>

Below what? you say!

Dear Stovers,
Check out Elsen's sawdust volcano, under the NEW, at the site below.

Alex

Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Web Site http://www1.kingston.net/~english/Stoves.html

 

From larcon at sni.net Thu Mar 12 19:09:15 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Forwarded: Commercial charcoal retorts
Message-ID: <v01540b00b12c9accba04@[204.133.251.16]>

(RWL): Stovers - this interesting message and request came in from
non-list member ["Dr. Charles H. Wilson" <chwwwt@usit.net>]:

West Wind Technology, Inc. is a biotechnology company that produces bamboo
plants. One of the end uses of bamboo is an extremely high quality
charcoal used in the Orient for goldsmithing and ceramic kilns. Since
bamboo is an extremely productive biomass (from 15 - 100 tons annually,
depending on species, growing site, etc.), and since it can be cut over and
over without replanting, it would be a good source of wood for
biomass/charcoal use. We would like to manufacture this charcoal in the
U.S. for sale as "lump" charcoal and activated charcoal. Are there any
commercial size retorts, ovens, etc. that can produce charcoal without
pollution problems?

===============================================================
Dr. Charles H. Wilson
West Wind Technology <http://esi.athenstn.com/wwt/wwt.html>
5 South Hill St. Athens TN 37303
Phone 423-745-5087 Fax 423-744-8689
"Get the facts first, then you can distort them as much as you want." M. Twain
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

 

 

From larcon at sni.net Sat Mar 14 21:49:34 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Living Dangerously - Carbonising Sawdust
Message-ID: <v01540b00b12f73760a02@[204.133.251.10]>

Stovers - some (hopefully not too stupid) comments and ideas on Elsen's remarks:

>Nearly lost my eybrows & shortened my hair significantly during the first
>'Grover mod. MkII' trial yesterday.
>
>This 'blast furnace' needs a governor! A mini Mt. Vesuvius of a volcano
>erupted out through the feedstock sawdust surrounding the
>chimney/combustion chamber in a jet of pure white smoke. I was standing
>uncomfortably close when ignited in a 2 meter tall flare filled with
>sparkling bits of igniting charcoal powder.

(RWL): This sounds pretty frightening. Take care. The following
written out of fear for your safety.

1. Maybe you could add a safety valve feature that allowed some
preferential venting inward into the combustion region - maybe something
that is spring loaded? Maybe also there could be a "baffle" that directed
big upward explosions away from the operator positions?
2. Maybe need a thermocouple to show the inner cylinder wall
temperature?
Maybe if it gets too hot (like the red-hot grate), it will be a
good spark plug for igniting the sawdust. Could the "explosion" be caused
when some air is allowed to enter through the charcoal exit port? I wonder
if a water or other type (rotating?) seal at the bottom might help prevent
air from getting to the hot charcoal>

>
>Due to the pressures within the pyrolysis jacket surrounding the
>chimney/combustion chamber, the aformentioed problem occurs occasionally,
>as well as quite a bit of carbonised sawdust being blown through the
>perforations under the grill. The larger particles drop down, but the
>smaller ones go up & are burnt along with flared gasses, causing a
>significant reduction in recovered carbonised sawdust.

1. Because of the hot gases above the grate, the pressure there
and below the grate will be lower than outside at the same height. So the
pyrolysis gases will be "sucked" out (and the combustion air will be sucked
up as well). Whether the pressure inside is higher or lower than the
outside pressure depends on the pressure drop across your perforations.
How large are those perforations and how many are there?

2. I wonder if a very fine grid (maybe even a flat "washer") on
the inside (towards the centerline) of the perforations would help to
capture more of these charcoal particles that are otherwise swept upwards.
What sort of percentage loss of particles do you think is now occurring
through this inward flow through the perforations?

3. A larger diameter inner tube would lower the inner air velocity
and allow more of the charcoal particles to fall rather than being swept
up.

4. Maybe there could be some sort of inner baffle with much
smaller holes to prevent the charcoal from getting to the perforations?

>
>Looking down the chimney (this is done very quickly & with great caution
>due to the heat), one see what appears to be the inside of a regular boiler
>furnace, with flaring gasses entering the chimney under pressure and
>creating a strong flue draft. The grill is heated to a bright orange
>colour. Very little (if any) wood need be added once the flaring commences.

(RWL): Better try a mirror too (top and bottom?)
>
>Trials continue today. I think this may be a step forward, but I'm
>intimidated by this machine. Have I created a monster? I need to learn how
>to control the rate of pyrolysis in order to reduce the dangers and to
>increase end product recovery.
>
(RWL):
1. The two Grover stoves that I have seen had no such control - and
adding a control mechanism to your mod isn't going to be obvious.

2. Maybe you can change the draft by changing the chimney height.
I'm not so sure that this is a great idea, but excess air will lower the
exhaust temperature

3. Maybe you can rotate the whole apparatus so as to get a smaller
effective chimney height.

4. You should get lower temperatures from going to a larger ID
device. Presumably there is some best combination of diameters and heights
when doing this for a one-person operation and another bigger "best"
combination if you have two, etc.

>This "stove" may have some other applications though...?
>
>I'll get a picture to Alex soon.
>
>>Regards; elk

(RWL): I sure hope you can find a way to use all that hot gas. Good to
hear that you haven't yet given up on your "monster". Best of luck and
please be careful to wear a hat at least. Ron

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

 

 

From elk at arcc.or.ke Sun Mar 15 23:50:16 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:35:50 2004
Subject: Carbonising Sawdust- ongoing trials
Message-ID: <199803160456.HAA11536@arcc.or.ke>

Respond to some of Ronals comments and questions on the Grover Modification
sawdust carbonising attempts;

> (RWL):
> 1. Maybe you could add a safety valve feature that allowed some
>preferential venting inward into the combustion region - maybe something
>that is spring loaded? Maybe also there could be a "baffle" that directed
>big upward explosions away from the operator positions?

I think operator experience is the best safety measure at present, but the
unit would have to be scaled up to meet my throughput requirements of around
1000 kg sawdust/day. I'm running at less than 200 kg/day in the current
configuation, and experienceing a sawdust to charcoal ration of a mere 1:0.15

> 2. Maybe need a thermocouple to show the inner cylinder wall
>temperature?

I don't have one, and have resisted involving instuments in my work to date-
even though I do love gadgets...

> Maybe if it gets too hot (like the red-hot grate), it will be a
>good spark plug for igniting the sawdust. Could the "explosion" be caused
>when some air is allowed to enter through the charcoal exit port? I wonder
>if a water or other type (rotating?) seal at the bottom might help prevent
>air from getting to the hot charcoal>

Most of the 'explosions' occure in the open air above the unit when a jet of
white smoke erupts from the sawdust input funnel and ignites in mid air. My
description of this as an exposion may be remiss, as there's no sound
accompanying the sudden flame.

> 1. Because of the hot gases above the grate, the pressure there
>and below the grate will be lower than outside at the same height. So the
>pyrolysis gases will be "sucked" out (and the combustion air will be sucked
>up as well). Whether the pressure inside is higher or lower than the
>outside pressure depends on the pressure drop across your perforations.
>How large are those perforations and how many are there?

There are about 80 3mm perforations in four rows within approx 4 cm band
around the inside chimney base 10 cm from the bottom of the longer inner
tube. The pressure inside the jacket, within the pyrolysing sawdust seems
primarily due to the pyrolysis process- volatiles - white smoke.
>
> (RWL):
> 2. I wonder if a very fine grid (maybe even a flat "washer") on
>the inside (towards the centerline) of the perforations would help to
>capture more of these charcoal particles that are otherwise swept upwards.
>What sort of percentage loss of particles do you think is now occurring
>through this inward flow through the perforations?

I'll think on that- if I'm getting 15 to 16% return (charcoal from sawdust)
then it must be at leat 5% loss, no?
>
> 3. A larger diameter inner tube would lower the inner air velocity
>and allow more of the charcoal particles to fall rather than being swept
>up.
>

Right. Need to play that against the corresponding heat loss, as I assume
that the more heat convected through the inner wall into the sawdust the
better...?

> 4. Maybe there could be some sort of inner baffle with much
>smaller holes to prevent the charcoal from getting to the perforations?

I'm concerned about clogging the holes. What I want to do next is to remove
the spiral roundbars on the inside of the jacket that impart the auger
effect and try a 'smoothbore' , simply banging the sides occasionally to
shift the sawdust down through the pyrolysis zone & out.

> (RWL):
> 1. The two Grover stoves that I have seen had no such control - and
>adding a control mechanism to your mod isn't going to be obvious.

I've put a big ?butterfly/ damper on the top of the chimney.
>
> 2. Maybe you can change the draft by changing the chimney height.
>I'm not so sure that this is a great idea, but excess air will lower the
>exhaust temperature

Should this unit be developed to a scaled up version using 200 l. drums, I
reckon it'll be pretty tall! May be necessary though.
>
> 3. Maybe you can rotate the whole apparatus so as to get a smaller
>effective chimney height.

I don't understand.
>
> 4. You should get lower temperatures from going to a larger ID
>device. Presumably there is some best combination of diameters and heights
>when doing this for a one-person operation and another bigger "best"
>combination if you have two, etc.

Right. This is the direction I'll go after studying the current prototype fully.

All the Best;

elk

 

 

From larcon at sni.net Mon Mar 16 01:19:59 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Re(2):Commercial charcoal retorts
Message-ID: <v01540b05b132561dac98@[204.133.251.24]>

 

Stovers: This is to follow up on the message from last Thursday from Dr.
Charles Wilson on looking for a clean charcoal making unit. I sent a short
message suggesting joining "stoves" - which has now occurred - and because
of a few further questions, Charles has added the following. I also ask a
few more questions below.

(From Dr. Wilson):
>Thank you for your kind suggestion that I join the List. Please enroll me.
>The Hiller Group in Tampa, FL (www.hillergroup.com) markets a Dutch
>charcoal retort that is alledgedly 100% non-polluting. It is a batch unit
>with two ovens per retort. The gases are burned with the novel idea of
>using the hot gases from one oven to start up the wood in the second and
>then vice versa. For about $1.3 million investment in 12 retorts (24
>ovens) 9,400 tons of charcoal can be produced at a rate of about 2.5:1 (raw
>material:charcoal).

(RWL): 1) This sounds like about 2 cents per kilo for capital
cost (assuming about a five year simple payback). Did I do that correctly?
2. What size are these ovens and what is the cycle time? What
labor requirements are required once the bamboo is on site? Can one start
with fairly wet input bamboo? Any data on harvesting and moving costs -
which might dictate where the kiln is located?
3. Can any list members in the Netherlands (or anywhere) comment
on the characteristics of this set of retorts/ovens? (maybe especially
pollution characteristics).
4. The "ovens" from Dr. Jury have some of this flavor - but all
located in one container. (See the recent sketch on Alex English web site
-
http://www1.kingston.net/~english/Stoves.html
It is not clear yet to me what the commercial status of Dr. Jury's
retort/oven is - but you may wish to get a price quotation from him - as a
design also reputed to be non-polluting.
5. Is it likely that the Dutch/Hiller system can be operated
without electricity? This is supposed to be an advantage of Dr. Jury's
system.
6. I like the basic idea of "using the hot gases from one oven to
start up the wood in the second and then vice versa". It is not quite
clear what this might look like however. I will look at the Hiller group
web site.
7. Are you now looking for alternatives (presumably being
concerned about costs and other characteristics - and should these
alternatives give you about the same approximately 1 ton/day yield?

>
>We would like to use bamboo from plantations now in place in Nicaragua
>and/or plant large tracts of bamboo in Florida to use as the raw material
>for lump charcoal.

(RWL): I am not sure what you mean by "lump". Is this processed
and formed into briquettes? It would not seem that bamboo could lead to
"lumps".

>
>However, a continuous process might work better. I have been utterly
>unable to locate any manufacturer of non-polluting charcoal in the U.S. A
>Missouri kiln is too polluting for us to consider.
>
>Any information you can provide for this quest for the charcoal grail would
>be most appreciated.
>
>===============================================================
>Dr. Charles H. Wilson
>West Wind Technology <http://esi.athenstn.com/wwt/wwt.html>
>5 South Hill St. Athens TN 37303
>Phone 423-745-5087 Fax 423-744-8689
>"Get the facts first, then you can distort them as much as you want." M. Twain
>-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-

(RWL): 1. We have had some discussion on this list about
modifying the simple batch circular cylinder designs (usually two rings
about 2 meter diameter, each of 1 meter height with a conical cap) so as to
be non-polluting. This would be based on our regular discussions here
about top lighting with vertical stacking, with a small chimney.
2. My hope still is to also find a way to capture the 50% (or
more) of lost energy. Any possible applications in either Nicaragua or
Florida for this energy?
3. List member Mike Antal has been developing a design that
presumably is non-polluting.
4. I hope other list members will chime in on Charles' observation
that he has only this one option for clean production of charcoal. Any
others known?

Regards Ron

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

 

 

From elk at arcc.or.ke Mon Mar 16 08:07:00 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:35:50 2004
Subject: Charcoal Briquettes from Vendors Waste- Economics Update
Message-ID: <v01510101b132f0815a5e@[199.2.222.136]>

Stovers;

I sincerely hope that the silent majority of our group isn't getting fed up
with all the traffic on charcoal!

I, for one certainly appreciate crest's ongoing support of this topic
within the stoves group, and in perticular, Tom, Ronal and Alex's input.

The current economics of my briquetting work here in Nairobi is
interesting. I've been producing an average of 225 kg (dry) briquettes per
day with a team of three and occasionally some transport input. Please note
that I do mill the charcoal fines in a hammermill prior to briquetting.

To date my team has manually produced approx 23 tons of clay-bound
briquettes with a replacement and maintenance cost to the briquetter of
less than US $25.00

I have currently been able to negotiate a 6000 kg load of vendor's waste
for the equiv. of US $33.33- that's $.006 per kg. Vendor's are quite happy
to be rid of this bulky nuisance material, and I suspect that it could be
obtained free of charge in many instances.

Note that unsaleable fines comprise between 10 and 20% of a bag of charcoal
after transport when received in Nairobi. This percentage is probably on
the increase as less and less hardwood charcoal is produced within Kenya,
and the softer charcoals crumble easier, producing a higher amount of
fines. If anyone has recent statistics on the consumption of charcoal
within Nairobi, I'm sure the calculated proportion of fines would be an
impressive quantity indeed.

Clay, used at 10% as a binder costs as much as necessary to dig, transport
and offload. There's plenty available within 1 km of my location.

Costs at present are:

Charcoal fines: .006
Transport: .006
Milling: .008
Clay all costs: .004
Briquetting labour: .050
Misc. costs: .010

TOTAL : USD $0.084 per kg dry wt. finished product.

This amounts to US $4.20 per 50 kg bag.

Currently, regular local charcoal costs in Nairobi vary between US $6.25
and $7.50 per bag, which may weigh as little as 40 kg. and contain fines.
My manufactured briquette has negligeable fines after transportation within
the urban area.

Realistically, then, a true cost comparison per kg between 'standard'
charcoal and the briquette made from fines (assuming a 40kg bag and 15%
fines with the standard charcoal) could be US $0.20 for regular charcoal
V.S. the cost of $.084 for my briquettes. The vendor's profit margin is
included in labour costs for the briquetted charcoal.

Summation: my briquetted charcoal costs less than half of the cost of
regular charcoal availble in urban Nairobi.

I'm currently sending out free samples to small kiosks and roadside
restaurants in Nairobi. Feedback to date has been 100% positive for these
commercial applications due to the prolonged burn time of the high-ash
briquette. Household use is mainly for slow-cooking bean dishes and
similar. An added benefit of the briquette has recently been pointed out in
that the briquette will self-extinguish in a regular household sized metal
'Jiko' if the primary air inlet door is closed. The half burned briquette
can be mixed with fresh material and relit at a later time.

I suggest that it's time to disseminate this technology with an aim to
utilising all currently wasted charcoal vendor's (and even producer's?)
fines wherever labour is inexpensive and available enough to warrant.

Help?

elk

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
______________________________

 

 

From chwwwt at usit.net Mon Mar 16 10:03:17 1998
From: chwwwt at usit.net (Dr. Charles H. Wilson)
Date: Tue Aug 31 21:35:50 2004
Subject: Commercial Charcoal Retorts
Message-ID: <v03102801b132ee8bd850@[205.241.213.38]>

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From larcon at sni.net Tue Mar 17 00:21:34 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Forwarded: Introduction of Sandeep Saxena (new member)
Message-ID: <v01540b04b1337645ffcb@[204.133.251.42]>

(RWL): Stovers - this message from Sandeep Saxena came in response
to my welcome and my request for a note of introduction to us all:

To Sandeep: Could you give us a little more background also on the
type of manufacturing and products in which you are now engaged?
In response to your question below, I can say that we are a group
of about 125 persons in about 25 -30 countries who are interested mainly in
improving (mostly cook-) stoves for developing countries. Recently, we
have (by default) also become a place to discuss the (especially
non-polluting) making of charcoal. In past months we have often discussed
cook stoves which have charcoal as a co-product.

Regards Ron

(From Sandeep):
Thanks for your mail. I found stoves site while trying to find out
the info about Non-conventional energy. It is indeed a very valuable &
informative site for everyone. I'd appreciated to sit quite sometime and
see the topics discussed on the list & look for suitable trade Tie-up. I
as an entrepreneur (Manufacturer) would like to be associated with anyone
willing to transfer the Know-how for commercial exploitation in this Power
Hungry country. As I am new I have no idea.. what is the basic aim of this
list ?? Also please accept my sincere apologies for sending Joining
message to the whole list (I hope..). I thought I was writing to a
gentleman named Stoves <g>. I'm looking for any product related to
Non-Conventional energy, which can be made (In-house) and marketed. LMK
if this is the right place for me.

Best Regards

Sandeep Saxena

Global Trends
82 Darbhanga Castle,
Allahabad 211_002, India
Telfax 91 532 600175

<global@lw1.vsnl.net.in>

PS: If the content is right & acceptable, pl. post this message on the
list.

(RWL): This was fine. Thanks Ron

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

 

 

From larcon at sni.net Tue Mar 17 00:21:53 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Re(2): Carbonising Sawdust- ongoing trials
Message-ID: <v01540b07b1337ba34295@[204.133.251.42]>

Elsen - Thanks for your response today on answers to my questions. A few
more here. I think you are doing great. I have dropped a few items in your
response.

>> (original RWL -1 ):
>> 2. I wonder if a very fine grid (maybe even a flat "washer") on
>>the inside (towards the centerline) of the perforations would help to
>>capture more of these charcoal particles that are otherwise swept upwards.
>>What sort of percentage loss of particles do you think is now occurring
>>through this inward flow through the perforations?
>
(Elsen-1)
>I'll think on that- if I'm getting 15 to 16% return (charcoal from sawdust)
>then it must be at least 5% loss, no?

(RWL-1R): This might say that about 1/4 of the particles were being
swept up - (your 5% loss) divided by (your 15% + your 5%). I guess the
issue is how to identify other loss mechanisms. Some loss could be due to
excessive temperature for some particles.

(Original RWL-2)):
>> 3. A larger diameter inner tube would lower the inner air velocity
>>and allow more of the charcoal particles to fall rather than being swept
>>up.
>>
(Elsen answer-2):
>Right. Need to play that against the corresponding heat loss, as I assume
>that the more heat convected through the inner wall into the sawdust the
>better...?
>
(RWL-2R): Good question. Maybe you can have too high a
temperature. Maybe someone on the list can suggest a best time-temperature
profile. It seems to me that your earlier report on throughput time showed
a very fast conversion - that might allow a larger recovery if slowed down.

I will report separately on my reading of a more full historical
report on charcoal making by Dr. Ronald Reno that I mentioned about a month
ago. But there was a general belief that slower was better - and weeks
were taken in some large "pits"

(Original RWL - 3):
>> 4. Maybe there could be some sort of inner baffle with much
>>smaller holes to prevent the charcoal from getting to the perforations?
>
(Elsen Response-3):
>I'm concerned about clogging the holes. What I want to do next is to remove
>the spiral roundbars on the inside of the jacket that impart the auger
>effect and try a 'smoothbore' , simply banging the sides occasionally to
>shift the sawdust down through the pyrolysis zone & out.
>
(RWL-3R): This worries me. I am afraid that you will not get as
good mixing. I think it is a great experiment though. Another possible
way to mix might be "end-threaded rods" that are "bolted" (or welded)
radially into the various circumferences. Those on the inner tube would
serve also to carry heat into the sawdust. I wonder whether it might be
easier to move the inner or the outer tube. What are the constraints in
terms of the input "hopper" etc?

(RWL original-4)
>> 1. The two Grover stoves that I have seen had no such control - and
>>adding a control mechanism to your mod isn't going to be obvious.
>
(Elsen-4):
>I've put a big ?butterfly/ damper on the top of the chimney.
>>
(RWL-4R): What differences do you see as you change this damper
control?

(RWL-original - 5)
>> 2. Maybe you can change the draft by changing the chimney height.
>>I'm not so sure that this is a great idea, but excess air will lower the
>>exhaust temperature
>
(Elsen-5)
>Should this unit be developed to a scaled up version using 200 l. drums, I
>reckon it'll be pretty tall! May be necessary though.
>>
(RWL-5R): Perhaps you don't have to scale as much vertically as you
scale up radially. Using the 200 l drum size, what number are you thinking
of as you weld them together? What might be the total height then?

(Original -6)
>> 3. Maybe you can rotate the whole apparatus so as to get a smaller
>>effective chimney height.
>
(Elsen-6)
>I don't understand.

(RWL-6R): Sorry. I am hoping that your system does not have to
operate vertically. If the axis was rotated downward by 60 degrees (so the
system axis is at 30 degrees from the horizontal), then the draft should be
approximately halved and approximately half the air flow should occur. I
say "approximtely" because the draft depends on both height and on
temperature - and I can't predict what happens to temperature
>>

>All the Best;
>
>
>elk

And the same to you. Ron

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

 

 

From antal at wiliki.eng.hawaii.edu Tue Mar 17 12:58:48 1998
From: antal at wiliki.eng.hawaii.edu (Michael Antal)
Date: Tue Aug 31 21:35:50 2004
Subject: Commercial Charcoal Retorts
In-Reply-To: <v03102801b132ee8bd850@[205.241.213.38]>
Message-ID: <Pine.HPP.3.96.980317075652.10903D-100000@wiliki.eng.hawaii.edu>

Dear Dr. Wilson: most "stovers" know of the University of Hawaii's (UH)
high-yield charcoal technology. In brief, the process offers a 40 to 60%
yield (dry basis) of a high quality, low volatile matter, lump charcoal
from wood logs, chips, cuttings, and other biomass (such as macadamia
shells). The reaction time is 15 min to about one hour in a semi-batch
reactor. We have operated a pilot plant here at UH for several years and
demonstrated the technology to many potential sponsors. UH has 2 U.S.
patents on the process, and patents pending in most countries of the
World. UH is now negotiating with 2 venture capital groups for exclusive
licenses. Until these negotiations are complete, UH remains open to
proposals from other interested investors. As in the past, I am happy to
send technical articles on our work to anyone who requests them. Finally,
I agree with you that bamboo should be a wonderful feedstock for charcoal
production. Best regards, Michael Antal.

 

 

From elk at arcc.or.ke Wed Mar 18 03:27:58 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:35:50 2004
Subject: Carbonising Sawdust - Reply to Ronal
Message-ID: <v01510102b1355548a67e@[199.2.222.132]>

 

In response to a few questions made my Ronal with reference to the trials
underway on carbonising sawdust:

With regards to throughput, I've measured to two units against each other,
and my earlier estimate was too high.

The larger (MK II) unit has effectively doubled throughput over the first
experimental unit, and results are now clear: 14% charcoal from air dried
sawdust over 2.5 hours processing time. This is a mere 8 kg/hr sawdust
input.

I need to get to over 1000 kg/day- hopefully within an 8 hr shift....
that's multiplying my current throuput by a factor of 16. I reckon it's
possible.

This brings up the issue of fast v.s. slow; I'm not sure I understand the
advantages of slow pyrolysis- greater % recovery? Higher 'quality'? The
University of Hawaii is getting 40%. Where is the added biomass coming
from?

With respect to the 'smoothbore' v.s. auger for moving the sawdust through,
my observations are such that I believe that very little bridging occurs
with charcoal particles from sawdust. The pyrolised material is dry,
non-tarry (not sticky) and non-hydroscopic, as well as taking up much less
space (less bulk) than raw sawdust. This progressive size reduction
attributable to pyrolysis lends itself to a controllable vertical motion
down within the jacket of the stove. The roundbar auger provided a channel
for volatiles to escape under pressure upward instead of being directed
down & flaring within the chimney as designed. Hence my eybrow searing
'explosions'.

I can't see anything but a vertical orientation emptying with ease or
managing an even pyrolysis within the jacket.

I'm in the middle of upscaling to the size of two 200 litre drums joined
on-end and standing vertically. I'll try an exit for the pyrolised material
which will involve dropping the entire inner chimney a couple cm and
thereby opening a gap at the bottom of the outer jacket.

The incredible heat produced by the small unit is certainly an intimidating
aspect when I consider scaling the unit up this much! I will have a
proportionately larger diameter combustion chamber/chimney, with a primary
air damper at the bottom instead of the top. The damper on top of the MK II
certainly reduced the overall reaction rate.

If I don't manage to produce a viable carboniser in this direction, I think
I'll have invented an industrial scale sawdust fired boiler anyway.....
anyone need some excess heat?

On a related issue;

I've found that by seiving the sawdust charcoal by hand through a
mosquito-mesh sized screen, the particle size is reduced and briquetting
via my manual method using 10% clay produces a much denser, compact and
harder briquette than if the carbonised material is briquetted in it's
original state. This is good, as I'm aiming to produce a small, portable
manual sawdust carbonising and briquetting plant that can be used in the
field without a hammermill- without electricity.

All for now;

elk

 

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
______________________________

 

 

From cbarre at cyberus.ca Sat Mar 21 21:15:10 1998
From: cbarre at cyberus.ca (Chris Barre)
Date: Tue Aug 31 21:35:50 2004
Subject: career information
Message-ID: <01BD550E.E7BD7C20@ip235.ts4.dialup.ottawa.cyberus.ca>

I am presently working in the research department at a bio-energy company specializing in fast pyrolysis. To take my career in a new direction, I am currently seeking employment elsewhere. My intentions are to remain in the energy field, and I am inquiring to this list about any potential job opportunities. Please contact me privately for a copy of my resume or any additional information.

Chris Barré

 

From larcon at sni.net Mon Mar 23 11:27:31 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Forward: Tuning of the combustion in a pellet burner.
Message-ID: <v01540b06b13c3c6cb9c2@[204.133.251.17]>

(RWL): Can anyone answer the the following request from a non-list member?

Regards Ron

Hi, I have a pellet burner which I would like to fine tune
for "optimum" performance.

The available parameter is the air inlet.

I know from the manufacturer that the content of CO2
should be 12%.

I know that it can be measured using some expensive
equipment e.g. www.bacharach.com - their portable combustion
analyzer.

Could the CO2 parameter be mapped to a CO parameter instead ?

Any hints on a method or instrument...

Thanks!

Best regards Anders S¯ndergaard <anders@ifad.dk>

 

 

From gpk at physics.unipune.ernet.in Tue Mar 24 02:29:03 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:50 2004
Subject: No Subject
Message-ID: <Pine.SOL.3.96.980324124012.2232B-200000@physics>

 

Friends,
Hello everybody. I am a new subscriber to this list. As this is the first
time I am communicating with all of you, I think I should write something
about myself.

My name is 'Priyadarshini' which in Sanskrit means 'a woman who looks upon
good things', i.e. an optimist (which I think I am!). My home town is Pune,
(close to Bombay on the Western Coast of India in the state of Maharashtra)
which is also called the Oxford of the East, because of the large number and
variety of educational institutes housed here.

I did B.Sc. in Physics from the Fergusson College, Pune and M.Sc. in Physics
from the Department of Physics, University of Pune. Right now I am about to
submit my Ph.D. thesis in Physics from the same Department. I work for an NGO
named Appropriate Rural Technology Institute (ARTI).

As a part of the B.Sc. as well as M.Sc. curriculum, we are supposed to conduct
a small research project. As my B.Sc. project I worked on hand-made sawdust
briquettes. I added clay (vertisol) to sawdust, made a dough and then shaped
it into balls to be sun-dried and then used as domestic fuel in wood burning
stoves. I found that the clay can not only serve as a binder but also act as
a regulator of the rate of burning of the briquettes. I optimised the
briquette composition and showed that this could be a better fuel than wood
if used in a stove of proper design.

One of my special subjects at M.Sc. was Energy Studies which involved
studying different nonconventional energy systems. For my M.Sc. project,
I studied the design of a biomass burning stove from the air flow dynamics
viewpoint. This stove design, called 'Vanjyoti' (the forest flame), works
particularly well with particulate biomass like sawdust. The biomass is
densely packed into the stove body leaving an L shaped tunnel for the passage
of air. I studied the air flow through the stove and introduced some changes
in the tunnel dimensions to optimise the air flow and improve the stove
efficiency. In the course of this work, I realised that for nonreplenishable
stoves like Vanjyoti (i.e. stoves where more fuel cannot be added during the
cooking process), the variation of energy output with time is a more important
factor than the overall stove efficiency. I therefore devised an efficiency
test which provided me with this information too. A paper based on this
efficiency test was presented in a national level conference and was well
appreciated.

My Ph.D. work however is in a field different from my earlier research
interests. I have worked on artificial synthesis of diamond from hydrogen-
methane gas mixture. (Not an entirely different field considering that
methane is a fuel and diamond afterall is nothing else but carbon!)

I am presently working as the Principal Investigator of a research project
entitled 'Briquetted Domestic Fuel from Charred Sugarcane Trash' funded by
the Department of Science and Technology, Government of India. The project is
housed at the Appropriate Rural Technology Institute (ARTI) which is an NGO
devoted to increasing the standard of living of the rural people through
application of modern technological and scientific knowledge. Ours is one
of the very few NGOs working for social welfare that are run by scientists and
technologists. Most of the NGOs in this field are run by social workers and
their work generally does not go beyond education, adult literacy, sanitation,
health care etc. which are by no means unimportant issues, but do not help
much towards self sufficiency of the rural people. We believe that with the
help of modern science and technology it is possible to improve upon the
traditional rural income-generating activities and also introduce new avenues
of income generation. If the rural people earn as much money as the urban
middle class, they will create the basic amenities for themselves.

ARTI has just completed two years and already we have about 16 different
projects mainly in the area of agricultural and horticultural technologies.
ARTI also works as a Technical Back up Support Unit (TBU) for the National
Programme on Improved Cookstoves run by the Ministry of Nonconventional
Energy Sources, Government of India. Our team has popularised a number
of improved wood burning stove models in the states of Maharashtra, Goa and
Madhyapradesh. We promote different types of stoves -single pot hole, two pot
hole, with chimney, without chimney, community stoves for hostels and hotels,
etc. We are also working on special purpose stoves such as bakery ovens,
stoves for sweetmakers, jaggerymakers, etc. A novel aspect of this activity
has been to train traditional potters in construction of the improved
cookstoves. This has provided a new business opportunity to the potters.
Some of our trained potters are today successful entrepreneurs with an annual
turnover of several million rupees.

In my project mentioned above, I am developing the technology of converting
dried leaves of sugarcane into char and making charcoal briquettes from this.
In the state of Maharashtra itself, several million tonnes of sugarcane trash
is generated every year and it is completely useless. The farmers cannot
afford to spend money even on the collection of the trash after harvesting
the sugarcane and it is generally burnt in situ. The idea behind the project
is to develop an easy-to-construct and -operate charring kiln and briquetting
machine so that the trash can be converted into a value-added product that
can be used as a domestic fuel instead of wood or coal.

A lot of work has been done on charring and briquetting of sawdust.The
sugarcane trash has its own problems. Firstly it is bulky and difficult to
handle. Secondly, it contains a number of noncombustible ingredients that
generate a lot of smoke and prevent the use of the trash as fuel in the
biomass form.

We have been successful in making char and briquetting it by using clay and
plant mucilages as binders. The briquettes burn quite well with a smokeless
flame. Dr. P.D. Grover of Indian Institute of Technolgy, Delhi has developed
a technique for making briquettes out of charred biomass. However these
briquettes have a specific geometry. The honeycomb geometry is important to
get the maximum fuel use efficiency. But because of this it also becomes
necessary to use a special stove design for burning these briquettes. We make
cylindrical stick briquettes that can be properly stacked to simulate the
desired honeycomb geometry and can be used equally efficiently as a fuel in
a stove of any geometry or size.

But the charring process is giving us quite a lot of problems. We need
a simple design so that the kiln can be constructed and operated even by an
illiterate person with minimal workshop facilities available. Presently
we are using an old steel barrel with an aerator of galvanised steel pipes
inserted into it. The barrel is filled with sugarcane trash and its mouth is
closed with clay. The air input is controlled by the simple device of opening
and closing the aerator inlets. A part of the trash is burnt to generate
the heat required to char the remaining trash. The process is fairly efficient
- we get about 4-5 kg of char from about 10 kg of trash. But it is a slow
process. It takes nearly 8 hours to char 10 kg of biomass. As our starting
material is completely useless, efficiency of the charring process is not a
very important criterion. Also for the same reason, we are not much bothered
about the loss of combustible gases in the charring process. On the other
hand, from a practical viewpoint, speed of the charring process does become
important. Every single farm generates tonnes of trash and the farmer would
prefer to be over and done with the briquetting process in a day or two. One
solution to this is to use a bigger kiln constructed out of bricks and mortar.
But that also means an increased construction cost. A farmer would not spend
so much money just for generating fuel for his household. Also such a kiln is
not portable and if a person is to make a business out of the briquette making
process, he would have to make arrangements for transportation of the trash.
A portable kiln and briquetting machine can be taken from farm to farm.

In view of these difficulties, we are now thinking of a different design. We
intend to make bundles of the sugarcane trash and manually push them
through a heated steel pipe. The pipe will be heated by burning some of the
sugarcane trash itself. Some care will have to be taken to ensure uniform
heating of the pipe (so as to ensure uniform charring) and also to prevent air
flow through the hot zone (otherwise the trash will burn instead of charring).
The rate of passage of the bundles and the pipe dimentions will have to be
optimised so that by the time a bundle emerges out of the other end of the
pipe it would be in the form of char. Alternatively, each bundle will have
to undergo multiple passes through the pipe. This would be a continuous process
amenable even to commercial scale production. We have yet to test the theory
though and I would certainly be grateful for your comments and suggestions
reagrding this.

Priyadarshini Karve.
gpk@physics.unipune.ernet.in
Priyadarshini Karve
Research Fellow,
Appropriate Rural Technology Institute (ARTI),
6, Koyna Apartments, S.No. 133, Kothrud,
Pune 411 029, Maharashtra, India.
Phone: 91 0212 342217/233258/331214

 

 

From larcon at sni.net Tue Mar 24 17:49:20 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Priyadarshini introduction to ARTI and stoves
Message-ID: <v01540b02b13da68f93df@[204.133.251.48]>

(Almost Dr.) Priyadarshini: Thank you for sending such a long and
interesting letter of introduction. Below are mostly questions and a few
suggestionss.

(Priyadarshini):
>As a part of the B.Sc. as well as M.Sc. curriculum, we are supposed to conduct
>a small research project. As my B.Sc. project I worked on hand-made sawdust
>briquettes. I added clay (vertisol) to sawdust, made a dough and then shaped
>it into balls to be sun-dried and then used as domestic fuel in wood burning
>stoves. I found that the clay can not only serve as a binder but also act as
>a regulator of the rate of burning of the briquettes. I optimised the
>briquette composition and showed that this could be a better fuel than wood
>if used in a stove of proper design.

(RWL): 1. What was the range of diameters of the "balls" and the
percent (by weight) of clay in these?
2. What were your criteria in optimization?
3. How do stoves for these "sawdust balls" differ from other stove
designs?
4. Did you ever make sawdust cylinders rather than sawdust balls?
5. Have you read any of our "stove list" literature over the last
several years on "charcoal-making cook stoves"? I believe that cylinders
might work better than balls in these designs _ although balls might work
pretty well also.
6. What is "vertisol"?

(Priyadarshini):
> <snip> For my M.Sc. project,
>I studied the design of a biomass burning stove from the air flow dynamics
>viewpoint. This stove design, called 'Vanjyoti' (the forest flame), works
>particularly well with particulate biomass like sawdust. The biomass is
>densely packed into the stove body leaving an L shaped tunnel for the passage
>of air. I studied the air flow through the stove and introduced some changes
>in the tunnel dimensions to optimise the air flow and improve the stove
>efficiency. In the course of this work, I realised that for nonreplenishable
>stoves like Vanjyoti (i.e. stoves where more fuel cannot be added during the
>cooking process), the variation of energy output with time is a more important
>factor than the overall stove efficiency. I therefore devised an efficiency
>test which provided me with this information too. A paper based on this
>efficiency test was presented in a national level conference and was well
>appreciated.

(RWL): I know the stove list would like to see and hear more
about this sawdust burning stove.
1) How can copies be obtained of the paper?
2) Briefly what are the best dimensions?
3) Did you control the air flow and if so how?
4. Could you describe the features of your efficiency test?
>
(Priyadarshini):
>My Ph.D. work however is in a field different from my earlier research
>interests. I have worked on artificial synthesis of diamond from hydrogen-
>methane gas mixture. (Not an entirely different field considering that
>methane is a fuel and diamond afterall is nothing else but carbon!)
>
(RWL): This probably is a long way from stoves, but I'm sure many
on the list would like to know if you were successful and what the basic
ideas are.

(Priyadarshini):
>I am presently working as the Principal Investigator of a research project
>entitled 'Briquetted Domestic Fuel from Charred Sugarcane Trash' funded by
>the Department of Science and Technology, Government of India. The project is
>housed at the Appropriate Rural Technology Institute (ARTI) which is an NGO
>devoted to increasing the standard of living of the rural people through
>application of modern technological and scientific knowledge. Ours is one
>of the very few NGOs working for social welfare that are run by scientists and
>technologists. Most of the NGOs in this field are run by social workers and
>their work generally does not go beyond education, adult literacy, sanitation,
>health care etc. which are by no means unimportant issues, but do not help
>much towards self sufficiency of the rural people. We believe that with the
>help of modern science and technology it is possible to improve upon the
>traditional rural income-generating activities and also introduce new avenues
>of income generation. If the rural people earn as much money as the urban
>middle class, they will create the basic amenities for themselves.

(RWL): very interesting organizational concept. What is the size
of the ARTI staff and budget?

(Priyadarshini):
>ARTI has just completed two years and already we have about 16 different
>projects mainly in the area of agricultural and horticultural technologies.
>ARTI also works as a Technical Back up Support Unit (TBU) for the National
>Programme on Improved Cookstoves run by the Ministry of Nonconventional
>Energy Sources, Government of India. Our team has popularised a number
>of improved wood burning stove models in the states of Maharashtra, Goa and
>Madhyapradesh. We promote different types of stoves -single pot hole, two pot
>hole, with chimney, without chimney, community stoves for hostels and hotels,
>etc. We are also working on special purpose stoves such as bakery ovens,
>stoves for sweetmakers, jaggerymakers, etc. A novel aspect of this activity
>has been to train traditional potters in construction of the improved
>cookstoves. This has provided a new business opportunity to the potters.
>Some of our trained potters are today successful entrepreneurs with an annual
>turnover of several million rupees.

(RWL): 1. Could you provide more detail on how your stove designs
are different for different states.
2. How much improvement are you finding after ARTI has been involved?
3. What is the nature of the stove improvements you propose
4. Are ARTI staff involved in the dissemination?
5. Will you eventually be working in all the states of India?
6. What is the exchange ratio between rupees and dollars? What
are typical prices of stoves?

(Priyadarshini):
>In my project mentioned above, I am developing the technology of converting
>dried leaves of sugarcane into char and making charcoal briquettes from this.
>In the state of Maharashtra itself, several million tonnes of sugarcane trash
>is generated every year and it is completely useless. The farmers cannot
>afford to spend money even on the collection of the trash after harvesting
>the sugarcane and it is generally burnt in situ. The idea behind the project
>is to develop an easy-to-construct and -operate charring kiln and briquetting
>machine so that the trash can be converted into a value-added product that
>can be used as a domestic fuel instead of wood or coal.
>
>A lot of work has been done on charring and briquetting of sawdust.The
>sugarcane trash has its own problems. Firstly it is bulky and difficult to
>handle. Secondly, it contains a number of noncombustible ingredients that
>generate a lot of smoke and prevent the use of the trash as fuel in the
>biomass form.
>
>We have been successful in making char and briquetting it by using clay and
>plant mucilages as binders. The briquettes burn quite well with a smokeless
>flame. Dr. P.D. Grover of Indian Institute of Technolgy, Delhi has developed
>a technique for making briquettes out of charred biomass. However these
>briquettes have a specific geometry. The honeycomb geometry is important to
>get the maximum fuel use efficiency. But because of this it also becomes
>necessary to use a special stove design for burning these briquettes. We make
>cylindrical stick briquettes that can be properly stacked to simulate the
>desired honeycomb geometry and can be used equally efficiently as a fuel in
>a stove of any geometry or size.

(RWL): 1. What is meant by "properly stacked"?
2. What are typical dimensions for these cylindrical sticks?
3. I gather that the biomass is to be charred in the field and the
resultant charcoal then combined with clay and sold as briquettes. Is this
correct?
4. Has anyone at ARTI looked into the capture of those waste gases
for cooking - presumably in a charcoal-making cook stove?
5. We have heard a bit about the Grover briquette shape. Could
your describe these more fully and the stove in which they are used?
6. We have had many discussions on this list about pollution
levels from stoves. Could you describe your cleanliness results in
quantitative terms?

(Priyadarshini):
>But the charring process is giving us quite a lot of problems. We need
>a simple design so that the kiln can be constructed and operated even by an
>illiterate person with minimal workshop facilities available. Presently
>we are using an old steel barrel with an aerator of galvanised steel pipes
>inserted into it. The barrel is filled with sugarcane trash and its mouth is
>closed with clay.

(RWL): 1. This is fairly clear and sounds simple enough.
However, we have a photo capability on this list supported through the
volunteer efforts of Alex English ( "*.English"
<english@adan.kingston.net>) with a web site at:
http://www1.kingston.net/~english/Stoves.html
Any photos you have on any of ARTI's stove and charcoaling investigations
can probably be handled by Alex, for the benefit of everyone.
2. This sounds like the field charcoaling is done with venting of
the pyrolysis gases rather than by flaring. Correct? (We have had
considerable discussion on the greater global warming damage done by
pyrolysis gases rather than CO2.)

(Priyadarshini):
> The air input is controlled by the simple device of opening
>and closing the aerator inlets. A part of the trash is burnt to generate
>the heat required to char the remaining trash. The process is fairly efficient
>- we get about 4-5 kg of char from about 10 kg of trash. But it is a slow
>process. It takes nearly 8 hours to char 10 kg of biomass.

(RWL): 1. Does the "old steel barrel" only contain 10 kG, or is
this just a ratio?
2. One key to our work on charcoal-making stoves has been top
lighting (with a small chimney and introduction of secondary air to achieve
flaring). Can you describe the means of lighting and whether a chimney has
ever been tried.
3. Your yield ratio of 0.4 to 0.5 seems very high. Can you
describe how this yield might vary with any parameter?

(Priyadarshini):
>As our starting
>material is completely useless, efficiency of the charring process is not a
>very important criterion. Also for the same reason, we are not much bothered
>about the loss of combustible gases in the charring process. On the other
>hand, from a practical viewpoint, speed of the charring process does become
>important. Every single farm generates tonnes of trash and the farmer would
>prefer to be over and done with the briquetting process in a day or two. One
>solution to this is to use a bigger kiln constructed out of bricks and mortar.
>But that also means an increased construction cost. A farmer would not spend
>so much money just for generating fuel for his household. Also such a kiln is
>not portable and if a person is to make a business out of the briquette making
>process, he would have to make arrangements for transportation of the trash.
>A portable kiln and briquetting machine can be taken from farm to farm.

(RWL): The historical approach (with wood) seems to have been
always to use "pits" with dirt walls where you now have steel. Do you
think this has any possibility of success for sugar can leaves?

(Priyadarshini):
>In view of these difficulties, we are now thinking of a different design. We
>intend to make bundles of the sugarcane trash and manually push them
>through a heated steel pipe. The pipe will be heated by burning some of the
>sugarcane trash itself. Some care will have to be taken to ensure uniform
>heating of the pipe (so as to ensure uniform charring) and also to prevent air
>flow through the hot zone (otherwise the trash will burn instead of charring).
>The rate of passage of the bundles and the pipe dimentions will have to be
>optimised so that by the time a bundle emerges out of the other end of the
>pipe it would be in the form of char. Alternatively, each bundle will have
>to undergo multiple passes through the pipe. This would be a continuous
>process
>amenable even to commercial scale production. We have yet to test the theory
>though and I would certainly be grateful for your comments and suggestions
>reagrding this.
>
> Priyadarshini Karve.
> gpk@physics.unipune.ernet.in
>Priyadarshini Karve
>Research Fellow,
>Appropriate Rural Technology Institute (ARTI),
>6, Koyna Apartments, S.No. 133, Kothrud,
>Pune 411 029, Maharashtra, India.
>Phone: 91 0212 342217/233258/331214

(RWL): This last process is something like an approach described
recently by a new list member Dr. Jury Judkevich, where the loose material
was enclosed in multiple cans (with holes in the bottom end only) which
were cycled into a large container. The escaping gases from each are
ignited and used to heat itself and neighbors.
Perhaps what Elsen has been doing with sawdust could be modified to
work with sugar cane leaves. Rather than "pushing" - his sawdust

My own personal hope is that a way can be found (after drying) to
shred the waste in the field, and to create a spherical or cylindrical
"briquette" which can be used in a cook stove - much as you have done with
sawdust and clay. The difference is that, in a charcoal-making stove, the
co-product output of charcoal can be sold (or used) to pay for (or offset)
the input fuel. I would hope that your experience with sawdust would lend
itself to such an approach. Is there any hope for this? Or must only
charcoal leave the field?

Thanks again for your great introduction. Ron

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

 

 

From global at lw1.vsnl.net.in Wed Mar 25 01:01:01 1998
From: global at lw1.vsnl.net.in (Sandeep Saxena)
Date: Tue Aug 31 21:35:50 2004
Subject: Priyadarshini introduction to ARTI and stoves
In-Reply-To: <v01540b02b13da68f93df@[204.133.251.48]>
Message-ID: <Pine.OSF.3.95.980325113946.14502A-100000@lw1.vsnl.net.in>

Hi Priya Darshini,

Your introduction was really impressive. Since you've told I want to add
here that this sweet name was given to our Iron lady Indira Gandhi by her
father Jawahar L.Nehru. I think you are late on this list but at the right
place now. know, if ARTI would like to promote their innovations in the
state of Uttar Pradesh.BTW, Let 's try to bring Dr P.D. Grover of IIT
Delhi on this list if he is not the member of this list. I'd attended a
national seminar 10 yrs back , where he presented a paper on " How to use
Agro waste as fuel in a boiler and get Activated carbon as a by-product".
I hope It will be easier for U to find his address on the Internet. I'm
also a new member on this list and impressed by the Study Material
available here.

Warm Regards Sandeep Saxena, Allahabad

oooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo

 

 

From gpk at physics.unipune.ernet.in Wed Mar 25 04:45:20 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:50 2004
Subject: Priyadarshini introduction to ARTI and stoves
In-Reply-To: <Pine.OSF.3.95.980325113946.14502A-100000@lw1.vsnl.net.in>
Message-ID: <Pine.SOL.3.96.980325140127.16553B-100000@physics>

Dear Mr. Saxena,
I am sending you the Annual Report of our institute by post so
that we may explore the possibilities of implementing some of our
technologies in Uttar Pradesh.
I had in fact expected that either Dr. Grover or some of his
students/colleagues would be members of this list. But it appears that is
not the case. As far as I know, Dr. Grover has retired from IIT, Delhi,
but I am sure somebody must be carrying on the excellent work that he
started there. I will try to find more about it from my other contacts. I
agree with you that he or his successors at IIT, Delhi would be able to
make valuable contributions to this list. If anybody else can locate him,
please do so.
Priyadarshini Karve

 

 

From gpk at physics.unipune.ernet.in Wed Mar 25 04:47:45 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:50 2004
Subject: Sugarcane leaves
In-Reply-To: <19980325063725.7865.qmail@hotmail.com>
Message-ID: <Pine.SOL.3.96.980325133455.16553A-100000@physics>

 

Dear Mr. Babu,
You are quite right about the problems involved in using sugarcane
leaves as fuel in the biomass form. It is too bulky and smoky to be used
as fuel in the form it is available. Chopping and briquetting may solve
the density problem. But sugarcane leaves contain silica which is highly
abrasive and leads to wearing off of the cutter. In fact when I was
working on hand-made sawdust briquettes, I also experimented with dry
sugarcane leaves, chopped up into small pieces (about 2-5 cm long), but it
did not work. The briquettes just disintegrated upon drying. At least as
far as compaction by hand is concerned, one must have fine grained biomass
like sawdust. I then thought that compaction with a
pelletising/briquetting machine may be the solution. Can you tell me what
methods you are using for briquetting the different types of biomass? But
in any case, the sugarcane trash does not burn very well and therefore
charring and then using the char as fuel may be a better idea. I have made
briquettes out of the char produced from sugarcane trash and they burn
quite well.
As far as charring of biomass is concerned I am myself new to this
field and as my earlier letter indicates, am more or less groping in the
dark! But I am convinced about one thing: If sugarcane trash is to be
converted into a useful fuel product, charring is the way to go.
Priyadarshini Karve.

On Wed, 25 March 1998, babu kann wrote:
> Hello Ms.Priyadarshini
>
> My name is babu and I am working on using differnt kinds of
> biomass waste for manufacturing briquettes. I have been
> working on this since 97 jan. I have used coffee husk,
> rice husk, sawdust, tamrind shell powder, bagasse, groundnut
> shell, cashew waste etc.
>
> I was working on sugaracane leaves waste and was not really
> successful in using it as a biomass fuel for briquetting
> For making briquetting in this particular type of mahine
> the size of the rawmaterial has to be around 8 mm in size
> and i had problems in chiping/ cutting the leaves to smaller
> size and the bulk density was very less.
>
> The sugarcane leaves were first sundried for few days in
> the open and then we tried feeding them into a pulveriser
> to get the required size of @8mm size but we were
> unsucessful.
>
> Yes you are right there are tonnes of sugarcane leaves
> that go as waste . I am still working on how to use it
> for making briquetts .
>
> Charring...well I dont have much idea about it can u send me more
> details on it .?
>
> If u have any suggestions on this i would be very grateful
>
> Babu .k.
> kitaz@hotmail.com
>
>
>
>
>
>
> ______________________________________________________
> Get Your Private, Free Email at http://www.hotmail.com
>

 

 

From gpk at physics.unipune.ernet.in Wed Mar 25 06:20:48 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:50 2004
Subject: Answers to RWL's Queries-1
In-Reply-To: <v01540b02b13da68f93df@[204.133.251.48]>
Message-ID: <Pine.SOL.3.96.980325140849.16553C-100000@physics>

Dear Dr. Larson,
Those are indeed a lot of questions! So I will answer them in
installments!
First, let's dispense with the nontechnical matters. So in this
installment I will give the information about ARTI and our improved stove
programme.
ARTI does not have any permanent staff, we are all (including the
President of the Institute) drawing salaries/honorariums from different
government funded projects and our 'employment' is limited to the duration
of the project. Naturally, we try and get a new project before the earlier
one ends! So this is a form of self employment. Generally at any given
time we are about 30 odd people working on different research projects.
Presently our annual budget is of the order of Rs. 50 million (1 dollar is
equivalent to about 35-40 rupees), but we are just two year old so the
budget and number of people will increase further.
As far as our improved stoves programme is concerned, the Ministry
of Nonconventional Energy Sources finances different Technical Back up
Units in different parts of the country. We are the official TBU for the
states of Maharashtra and Goa. The food habits of people vary from state
to state and accordingly different stove designs have to be developed to
suit the differing cooking habits. Therefore as far as the improved stove
programme is concerned, we have concentrated mainly on Maharashtra, Goa
and the adjoining states where people share the common cooking habits.
Even then, we have found that people in different regions prefer different
stove designs. (e.g. we found that people living in the coastal regions
where the atmospheric humidity levels are high do not like smokeless
stoves with chimney. This is because they want some smoke in the house to
keep away the dampness and mosquitos. Also since these are high rainfall
areas, the roof-to-chimney-pipe joint may leak during the rains.)
Therefore we promote a variety of designs and provide the design that best
suits the users' requirements. I will try and get some
photographs/drawings for the group in the near future.
We periodically conduct user feedback surveys to assess the impact
of the improved stoves on the people, particularly the rural housewives.
We have found that whenever the stoves are introduced by our own workers
or through other NGOs or by the local potters, the people are generally
happy. The Government run programme however is generally a failure. This
is because the government officials do not take enough trouble to educate
people in using the improved stoves. Also, the people are forced to take
whatever stove model that is available- they are not given a choice. In
order to promote the use of improved stoves, the Government has subsidised
the stove prices and a first-time user gets the benefit of the subsidy.
These are all mud stoves and they last about an year or so. We have found
that when the stove installation programme is implemented through NGOs or
trained potters, next year the users are willing to pay a much higher
price to buy a new improved stove rather than going back to the
traditional models. The biggest benefit that our users' claim is the
reduction in smoke and soot emission. The reduction in fuel consumption is
of secondary importance to them.
Our stoves are essentially based on the principle of using a grate
below the fuel and another grate at the top to direct the flames towards
the center of the pot. The efficiencies range from 20% to 35% depending on
the stove model. The stoves are constructed out of mud and the main price
contribution comes from the grates and the chimney in case of smokeless
stoves. The actual cost may range from Rs.100 to 200, but the user pays
only about half of it due to the subsidy. We are right now investigating
whether the cast iron grates can be replaced by other cheaper materials so
as to reduce the construction cost. We have designed molds for making the
different stoves and our trained potters are supplied with these molds so
that the optimal stove dimensions are accurately maintained. We also
conduct inspection surveys to ensure that the potters do a right job.
Every year we conduct training courses as well as refresher
courses for potters as well as stove users in different administrative
blocks of Maharashtra and Goa. We also conduct awareness generation
workshops for other NGOs. In view of the failure of the Government
agencies to implement the improved stove programme, we now take the
government targets on a contract basis and complete the targets through
our trained potters. In this manner, we also ensure work for our trained
potters.
As far as our other projects in the agricultural and horticultural
technologies are concerned, we have already initiated work in several
states all over India. But as the improved stove designs have to be
area-specific, we have concentrated only on Maharashtra and Goa primarily.
In Madhya Pradesh, we have installed a number of community stoves in the
government-run residential schools for the tribal children, government
guest houses, and some religious establishments.
That is all for now. Thank you for your interest in our work.
Priyadarshini Karve.

 

 

From larcon at sni.net Wed Mar 25 09:11:18 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Forwarded: Request for Help
Message-ID: <v01540b02b13eb5664ea6@[204.133.251.23]>

(RWL) Stovers - can anyone add more? Maybe especially a single
article in an easy-to-obtain journal? I know of none.

Renato - Most of the members on this list are interested mainly in work in
developing countries - so our expertise is mostly on natural charcoal,
rather than on briquettes. But both are covered in our recent web
archives, which I presume you have already found? Best of luck.

>From Renato:
Please help me if you can.

My grandson is writing a term paper on how charcoal briquettes are made.
He has asked me how it is done. I don't have a clue.

If you know, would you be so kind to tell me the basic steps involved?

Thank you for your support in this matter.

Renato Rindone, <rrindone@pacbell.net>

Phone (916) 966-4460

 

 

From REEDTB at compuserve.com Wed Mar 25 09:18:37 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:35:50 2004
Subject: Tuning combustion in a pellet burner; corn burning
Message-ID: <199803250924_MC2-37E4-9F10@compuserve.com>

Dear Anders:

You asked about optimizing the combustion in a pellet stove for CO or CO2.

Our hardware store sells a relatively inexpensive digital CO meter ($65)
that can detect a cigarette across the room. I believe the OPTIMUM
operation of your pellet burner could be the point at which CO becomes
minimal and trivial, but there is not TOO much excess air. Excess air
could also INCREASE CO if the fire area is chilled.

If you try this, I hope you will report back to the CREST groups
GASIFICATION and STOVES, as we would all be interested.

I have seen corn burning pellet stoves advertised. Corn is Mother Nature's
pelletized fuel! One's first reaction is that it is a crime against
starving humanity to burn corn in a stove. My second reaction is that corn
is such a widely spread commodity and so cheap (about $100/ton with corn a
$3/bu) that it could make sense in a lot of situations. At least, it is
better to burn the corn directly at 80% efficiency than to convert it to
ethanol with much lower efficiency. Have you tried corn?

We would like to appoint you our pellet stove research expert. Thanks for
your question.

Yours truly, TOM REED

 

From tmiles at teleport.com Wed Mar 25 11:36:49 1998
From: tmiles at teleport.com (Tom Miles)
Date: Tue Aug 31 21:35:50 2004
Subject: Sugarcane leaves
In-Reply-To: <19980325063725.7865.qmail@hotmail.com>
Message-ID: <199803251643.IAA04111@mail1.teleport.com>

Priyadarshini Karve,

Thank you for your comments on sugar cane leaves and bagasse. We have worked with sugar can tops and leaves as part of the International Cane Energy Network that is coordinated by Winrock (Winthrop Rockefeller Foundation). As you say they are difficult to work with. The Cane Energy Network members have done a variety of combustion trials with tops and leaves.

As part of our gasification project in Hawaii we have been using a forage choppper to reduce the bulk of bagasse (and irrigation tubing) from the mill. The chopper has worked reasonably well and may be a good tool for reducing tops and leaves for densification. We have done much densification over the years. Recently we have cubed and pelleted the choppped bagasse, again with success. As you realize preparation is the key to any ag residue processing. Chioppig may be part of the answer.

rtegards,

Tom Miles

------------------------------------------------------------------------------
Thomas R. Miles tmiles@teleport.com
Technical Consultants, Inc. Tel (503) 292-0107/646-1198
1470 SW Woodward Way Fax (503) 605-0208
Portland, Oregon, USA 97225

 

From english at adan.kingston.net Thu Mar 26 07:42:03 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:50 2004
Subject: Tuning of the combustion in a pellet burne
Message-ID: <199803261248.HAA07371@adan.kingston.net>

 

Hello Anders,
I have played around with testing a pellet stove, and other wood
and oil burners, using some Bacharach instruments. It would make
sense for the technicians who service oil and gas furnaces to add
pellet stoves to their list. I don't know of any cheep instruments
which can be relied upon. I think your best option would be to adjust
the air supply in relation to the flames appearance.

As you reduce the air the flame should gradually change from a short
bright yellow to a taller deep orange, eventually the tips of the
orange flames will develop black smoky tips. With some of the older
oil burners the optimum air was usually just before the flame tips
became smoky. With your pellet stove I would say give it a little
more air than that, until the orange flame brightens a little. You
likely have a very good view of the flame, and can watch it
frequently to see if this is a stable condition. If it is not, give
it more air. Check your flue for any carbon deposits.

This will need to be done for each of the feed rate settings.
This should help to optimise the efficiency of your heater.

Let us know how it goes in practice.

Regards, Alex

>
> Hi, I have a pellet burner which I would like to fine tune
> for "optimum" performance.
>
> The available parameter is the air inlet.
>
> I know from the manufacturer that the content of CO2
> should be 12%.
>
> I know that it can be measured using some expensive
> equipment e.g. www.bacharach.com - their portable combustion
> analyzer.
>
> Could the CO2 parameter be mapped to a CO parameter instead ?
>
> Any hints on a method or instrument...
>
> Thanks!
>
> Best regards Anders S_ndergaard <anders@ifad.dk>
>
>
>
>

 

 

From larcon at sni.net Thu Mar 26 21:54:05 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Forward: Tuning combustion in a pellet burner; corn burning
Message-ID: <v01540b04b140aacffef6@[204.133.251.38]>

Stovers: Ed Woolsey's response to Tom Reed got through on the gasification
list, but not on the stoves list as he is not a list member. (Ed - let me
know if you would like to follow more closely our stoves and charcoaling
debates as a fellow "stoves" list member.)
Regards - Ron

Mr. TOM REED:
The remark about ethanol ended my lurking. The renewable energy community
has too much respect for your opinions to let you get by so easily.

Better to burn corn that convert it to ethanol??? I suppose it depends on
if you want to "drive/fly" it or sleep beside it. The "value" of liquid
transportation fuels are higher than solid fuels.

Tom Öhere is a challenge, you get to the BioEnergy 98 Conference with a
gasifier fueled vehicle and Iíll go with an ethanol fueled vehicle. DEAL?
(Weíll discuss the bet later) Then if your still feeling froggy Iíll drink
a shot of ethanol if youíll breath your biogas for one minute.

The "Leopold Center for Sustainable Agriculture" in Ames, Iowa, says that
corn can be grown sustainably. Hummm sustainable corn and corn processed
by a renewable fuel. It will happen!

One could say that gasifiers will increase the economics of wood to
electricity and speed the destruction of the rainforestÖ.. or increase the
economics of sugarcane production, with all of the surrounding environmental
and social issuesÖ..or talk about the residue left from the old coal
gasifiers (read Superfund site) Öetc.

I donít think there is any "free lunch" out here. All of our houses have
windows, if you quit throwing rocks at ethanols, maybe they wonít start
throwing rocks at yours. There is too much at stake in this country/world
with respect to sustainability issues for infighting in the renewable energy
community. If your piece of the pie is not big enough, then lets make the
pie bigger.
(see ya in Madison?) :)
Sincerely
Ed Woolsey

 

>(snip)
>$3/bu) that it could make sense in a lot of situations. At least, it is
>better to burn the corn directly at 80% efficiency than to convert it to
>ethanol with much lower efficiency. Have you tried corn?
>
>We would like to appoint you our pellet stove research expert. Thanks for
>your question.
>
>Yours truly, TOM REED
>

 

 

From gpk at physics.unipune.ernet.in Fri Mar 27 02:31:07 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:50 2004
Subject: Answer to AWL's queries-2
Message-ID: <Pine.SOL.3.96.980327130717.4773D-200000@physics>

 

Dear Dr. Larson,
Here are the details of the 'sawdust balls' work that I have done.
Since the sawdust balls were made by hand, not much accuracy could be
maintained in their size. But these were approximately the size of table
tennis balls.
I studied the sawdust+clay compositions with 0, 10, 20, 30, 40 and 50
percent clay. The clay used was 'vertisol' which is the alkaline black clay
produced by weathering of basalt rock. This is the commonly available clay in
the 'Deccan plateau' region of Maharashtra which is where my home town Pune is
situated. The stove used for the study was an ordinary charcoal burning stove.
Three parameters were studied for deciding the best sawdust+clay composition.
These were (1) the fuel use efficiency (determined by the boiling and evaporation
efficiency test procedure), (2) Colour (determined by visual observation) and
temperature (determined by inserting a thermocouple rod into the flame just
below the pot) of the flame, (3) Amount of smoke (determined by visual observation)
and soot (the bottom of the pot was scraped after the efficiency test and the
soot thus collected was weighed using a microbalance) generated. The main
criterion for selection was of course the highest stove efficiency.The flame
colour and temperature were used mainly to try and assess the role of the
added clay in the combustion process. In addition, the 'best composition'balls
were also tested in an improved wood burning stove called 'Priyagni (beloved
fire)' which is a portable cast iron stove developed by the Rural Energy
Laboratory of Central Power Research Institute, Bangalore. This was done to
study the influence of stove design on the burning characteristic of the fuel.
I found that for the charcoal stove, the best efficiency (~26%) and
a reasonably low smoke and soot emission resulted for 90% sawdust+10% clay.
Interestingly, this performance was even better than the pure sawdust balls
(which were made by using a few drops of a commercially available gum as the
binder). This suggested a more constructive role on part of the vertisol clay
than just its action as a binder. It was also observed that the flame became
bluer and hotter with increasing clay percentage from 0 to 30% but with further
increase, the flame once again became progressively yellow. It was observed
that the blue flame was suspended in air slightly above the fuel mass, just
below the bottom of the pot. This suggested that the clay in some way promoted
gasification of the sawdust upto a certain limit. The time required to bring
the water (3 lit) to boil was also noted in each efficiency test and it was
found to increase from about 15 min for the 0-20% clay compositions to as
high as 40 min for the 50% clay composition. This may have been due to the
fact that the vigour and height of the flame was observed to decrease with
increasing clay % thereby affecting the heat transfer efficiency.
Interestingly, although the time required to boil the same amount of water
increased with increasing clay % it also reduced the amount of sawdust
required to do the job. For the 'best'composition, 400 gm balls (360 gm
sawdust) were required to bring the water to boil whereas for the 40% clay
composition it required 500 gm balls (only 300 gm sawdust). It was therefore
concluded that the clay acted as a damper making the fuel last longer.
Although I did not pursue this work further, I think it would be
interesting to study the chemistry involved in the combustion of the biomass+
clay system. Is the effect peculiar to the vertisol clay? Or is it just the
effect of the increased binding resulting from the addition of an increasing
amount of clay? But then we also tried to improve the binding by adding gum
to the sawdust+clay mixture and it made the balls unbreakable while handling
but did not really influence the burning characteristic. I do not really know
what was happening in there.
In the case of the charcoal stove experiments I had a feeling that
there was perhaps not enough space below the bottom of the pot to supply
a sufficient amout of secondary air for proper burning of the combustible
gas. This problem was solved by using the 'Priyagni' stove which is designed
for the much more vigourous flames resulting from combustion of wood and
therefore there is a lot of space between the fuel and the bottom of the pot.
And sure enough, the 'Priyagni' stove which gives about 26% efficiency for
wood gave nearly 30% efficiency and near-zero smoke and soot emission for
the 10% clay+90% sawdust balls.
To answer the remaining of your queries regarding this work:
No, we did not use cylinders. The reason for using balls was the large
surface area to volume ratio (as the compact briquettes burn from the surface)
and that this shape gives a more close packing in the firebox, leaving a regular
array of empty spaces for circulation of air (perhaps it is my physics
background that makes me favour the symmetric spherical shape!). In any case,
if one is to make the biomass briquettes using a mechanised process, the
cylinder would be a more convenient shape. I do not think the shape would
matter much in the overall scenario, though the size may be important. I have
not tried to optimise the ball size in my work.
I have glanced through some of the literature in the stove list on
charcoal making stoves. This is a new concept for me and I am trying to get
more information. The way I understand it,if one is interested in burning the
outer surface of the briquette for charring the inner volume of biomass, then
one should go for a shape with the least surface area to volume ratio (i.e.
if one is interested in the charcoal alone). That certainly rules out the
spherical ball shape. Am I right? Incidently the ash that we obtained after
burning our sawdust balls did not appear to contain any char (it looked white)
though we did not really analyse it properly.
I hope this gives enough information about the biomass balls. I will
try and get hold of a good picture of the 'Priyagni' stove design in the near
future.
Priyadarshini Karve

 

From woodcoal at mailbox.alkor.ru Fri Mar 27 07:09:21 1998
From: woodcoal at mailbox.alkor.ru (Woodcoal)
Date: Tue Aug 31 21:35:50 2004
Subject: Answer to AWL's queries-2
Message-ID: <199803271214.PAA25842@ns.alkor.ru>

Dear Karve
I think, in your work the most interesting this use of clay. It is
important to know structure of clay. Probably there there are a lot of
salts of aluminium, which helps complete combustion (kataliz). If such
pellets (cylinders or spheres) to heat up without oxygen the good coal for
household furnaces can turn out. I would like to recommend you our
technology for reception coal. It cheap, simply also does not give harmful
gases. About it you were written of the Dr. Larson .

Sincerely Jury Judkevitch (Rossia)
----------
> Îò: Priyadarshini Karve(SBO) <gpk@physics.unipune.ernet.in>
> Êîìó: stoves@crest.org
> Òåìà: Answer to AWL's queries-2
> Äàòà: 27 ìàðòà 1998 ã. 21:08
>
>

 

From english at adan.kingston.net Fri Mar 27 07:42:37 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:50 2004
Subject: Tuning of the combustion in a pellet burne
In-Reply-To: <199803261248.HAA07371@adan.kingston.net>
Message-ID: <199803271249.HAA13773@adan.kingston.net>

Some more for Anders and others,

> >
> > Could the CO2 parameter be mapped to a CO parameter instead ?

The standard method is the relate the CO2 and CO . Most would say
that you have to have both to know what is going on. My experience
with combustion that occurs in a closed container with a clearly
vigorous flame, and sampling in a chimney, suggest that selecting
the air setting which minimizes the CO will give you an acceptable
and close to optimal set point. This is not true for burners that
seek to minimize other emissions such an NOx.

To make sure that you are not seeing a large dilution from unreacted
air, I would find this point of lowest CO working from a rich flame.
Add increasing amounts of air until the CO has dropped the most.
A point of diminishing returns, where continuing to increase the air
supply will only slightly lower or even increase CO.

Alex

> > Any hints on a method or instrument...

> >
> > Thanks!
> >
> > Best regards Anders S_ndergaard <anders@ifad.dk>
> >
> >
> >
> >
>
>
>

 

 

From larcon at sni.net Fri Mar 27 17:33:37 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:50 2004
Subject: Re(2A): Answers to RWL's Queries-1
Message-ID: <v01540b06b141cc142d75@[204.133.251.10]>

Priyadarshini:

(RWL) Thank you for your response #1. The few questions below show
how good a job you did.

Priyadarshini
> <snip> (e.g. we found that people living in the coastal regions
>where the atmospheric humidity levels are high do not like smokeless
>stoves with chimney. This is because they want some smoke in the house to
>keep away the dampness and mosquitos.

(RWL): We of course have been trying to get smokeless stoves - for
health reasons. I have heard also that smoke was needed to help preserve
grass roofs. Do you or does anyone on the list know of authoritative
studies on the effectiveness of smoky stoves vs smokeless stoves under
otherwise identical conditions in these non-cooking functions? Would a
reduction by 90% still do the job? I have been in thatch roof homes where
I could not stay.
Kirk Smith?

Priyadarshini
> <snip> We have found
>that when the stove installation programme is implemented through NGOs or
>trained potters, next year the users are willing to pay a much higher
>price to buy a new improved stove rather than going back to the
>traditional models. The biggest benefit that our users' claim is the
>reduction in smoke and soot emission. The reduction in fuel consumption is
>of secondary importance to them.

(RWL): Does this apply in all areas or only in areas where they
have not already "requested" smoke?

Priyadarshini:
> Our stoves are essentially based on the principle of using a grate
>below the fuel and another grate at the top to direct the flames towards
>the center of the pot.

(RWL) I do not understand the upper grate idea and do not recall
seeing it earlier. This is a piece of metal with a central hole set below
the clay or mud surface where the cook pot is sitting? This is done either
with or without a chimney? What should be the size of this hole and how
much below the cook pot?

> <snip> The efficiencies range from 20% to 35% depending on
>the stove model. <snip>

(RWL): These are very good efficiencies. Can you suggest how much
the upper grate helps to raise this efficiency? Can you suggest where the
remaining lost energy is mostly going? What would be your next several
steps if people wanted higher efficiencies - say for about twice the
present stove price (which seems now to be about US $5.00 or less)?

Your description of your ARTI program sounds very well thought out.
More countries obviously need a Ministry of Nonconventional Energy Sources.

 

Regards Ron

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

 

 

From larcon at sni.net Fri Mar 27 17:33:47 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Re (2B): Answer to RWL's queries-2
Message-ID: <v01540b07b141d2c4bfa3@[204.133.251.10]>

Responding again to Priyadarshini:

1, First - you are hard to keep up with - a great deal of valuable
information! Again I shall try to ask few questions and not repeat all of
your response.

2. Priyadarshini <snip>
>Interestingly, although the time required to boil the same amount of water
>increased with increasing clay % it also reduced the amount of sawdust
>required to do the job. For the 'best'composition, 400 gm balls (360 gm
>sawdust) were required to bring the water to boil whereas for the 40% clay
>composition it required 500 gm balls (only 300 gm sawdust). It was therefore
>concluded that the clay acted as a damper making the fuel last longer.

(RWL): This seems to contradict your statement that the 10% clay
balls were the most efficient. What was the amount of water being brought
to a boil?

> <snip> I do not really know
>what was happening in there.

(RWL) I believe that really understanding a stove and this sort of
combustion is about as hard a problem as one can imagine - say in terms of
developing a time-dependent model. I think you know more than most of us.

Priyadarshini:
> No, we did not use cylinders. The reason for using balls was the large
>surface area to volume ratio (as the compact briquettes burn from the surface)
>and that this shape gives a more close packing in the firebox, leaving a
>regular
>array of empty spaces for circulation of air (perhaps it is my physics
>background that makes me favour the symmetric spherical shape!). In any case,
>if one is to make the biomass briquettes using a mechanised process, the
>cylinder would be a more convenient shape. I do not think the shape would
>matter much in the overall scenario, though the size may be important. I have
>not tried to optimise the ball size in my work.

(RWL): I asked about cylinders because the charcoal-making stove
works very well with the wood stacked vertically. But I think close-packed
spheres may also work well. In fact maybe tomorrow I will try to make
some.
The subject of pyrolyzing sawdust has been a major topic of our
discussion in the last several months as Elsen Karstad has reported on the
difficulty he has had in making sawdust/clay cylinders using a human
powered extruder. I'll bet that Elsen can also soon report on table tennis
sized spheres in a charcoal-making stove. This looks like it has a chance
of solving the dual problems of making charcoal and using the waste heat.

> I have glanced through some of the literature in the stove list on
>charcoal making stoves. This is a new concept for me and I am trying to get
>more information. The way I understand it,if one is interested in burning the
>outer surface of the briquette for charring the inner volume of biomass,

(RWL): We see essentially no "burning" (no ash). Only pyrolysis
occurs because of the extremely small amount of primary air allowed to
enter from the bottom - going past only "cold" biomass until reaching the
pyrolysis zone. Above that zone, the pyrolysis gases contain no oxygen and
the charcoal above continues to be heated and drive off more gases. The
pyrolysis zone moves down by efficient heat transfer due to radiation. The
gases are all moving due to the small chimney affect after combusting these
pyrolysis gases with secondary air. We rarely see any white ash anywhere.

>then
>one should go for a shape with the least surface area to volume ratio (i.e.
>if one is interested in the charcoal alone). That certainly rules out the
>spherical ball shape. Am I right?

(RWL): I am hoping not. The cylinder does a good job and I think
the sphere would also. My guess is that the best size sphere depends on
the desired power output. We can achieve a turndown ratio of about 3
through primary air control alone and power output is surprising constant -
one need adjust the primary air setting every fifteen minutes to maintain a
simmer for instance.

All of us have found that tight packing works best (avoiding zones
that move down faster than the average). Thus it is possible that your
spheres will work even better than cylinders. I hope so. They will solve
Elsen's original problem of not being able to hand form cylinders of
sawdust (but forming cylinders of charcoal/clay was easy). I think Elsen
liked 10% clay best also.

Again, thank you for wonderful replies. Ron

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

 

 

From gpk at physics.unipune.ernet.in Sat Mar 28 01:03:24 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:51 2004
Subject: answers to RWL's queries-3
Message-ID: <Pine.SOL.3.96.980328113932.14814A-200000@physics>

 

Dear Dr. Larson,
Sorry for typing the wrong initials in the subject line of my
earlier communication.
I am aware that I am writing rather long communications. But the thing
is that till I quite accidently stumbled onto this discussion group, I had
been working without access to any really scientific information in this area.
I have gone through the archives here and I find that I am not familiar even
with the basic terminology. The ideas that I have used in my work are based
on some very rudimentary, highschool-level knowledge of the combustion
phenomenon. Therefore I request all of you to tell me whether I have been
going in the proper direction or not.
Thanks for your response so far. I will address the second batch of
queries a bit later.
Here are the details of my work on the biomass burning stove,
'Vanjyoti'. Some of this may be relevant to the charcoal making stove, though
I have not yet quite grasped the idea.
The basic design of the Vanjyoti stove consists of a metal drum. It
has a side opening near the bottom. A metal cylinder is attached to the side
opening, extending into the drum. Another cylinder is provided with the stove.
For stoking up the stove, the second cylinder is placed vertically at the
center of the drum. This cylinder and the fixed cylinder at the bottom form
an L shape. Biomass is packed into the empty space surrounding this L. Dense
packing of biomass is the key to proper operation of the stove. Consequently
it gives the best performance with densely packable fine particulate matter
like sawdust. Once the drum is packed with biomass, the central cylinder is
gently removed. This leaves an L shaped cavity in the biomass- the walls of
the horizontal arm of L are formed by the fixed cylinder at the bottom and
the walls of the vertical arm are made of the packed biomass itself. There is
a lid for the drum. It has an opening at the center, of the same diameter as
that of the L shaped tunnel. There are pot raisers on the lid so that when a
cooking pot is kept on the stove there is a gap between the top of the stove
and the bottom of the cooking pot. The fire is started by introducing a
burning stick from the side opening at the base of the vertical arm of the L.
The basic design has undergone many variations over the years. Perhaps all
of you already know of this under a different name. The particular model
that I studied in this work is called 'Navjyoti' (new flame). This design is
developed by the Technical Back up Support Unit at Indian Institute of
Technology, New Delhi and is claimed to be an improved design with an average
efficiency of 25%.
I observed this stove in operation and found that there was further
scope for improvement as there was a lot of smoke emission throughout the
stove operation.
The single most important factor that decides the completelness of
combustion is the air supply to the fuel mass and the air currents through
the stove also decide the flame direction. I did some theoretical
calculations based on a highly simplified analysis of the air flow dynamics
through the L shaped tunnel and juggled around with the tunnel dimensions. I
found a design that gave 30% efficiency as against the 25% claimed for the
Navjyoti model. According to my design, for the Navjyoti stove drum of height
33 cm and diameter 23 cm, the tunnel diameter should be 4 cm (as against
7.5 cm recommended by Navjyoti designers) and the pot raiser height should be
2 cm (as against the recommended 1 cm). With these design modifications, I
could see that mostly gas was coming out from the top of the stove, it was
getting ignited due to the secondary air below the cooking pot and there was
a blue flame suspended there on top of the L shaped tunnel. At the same time
I also realised why the IIT designers had not recommended these stove
dimensions. The power output rating of my improved design was very very low.
An efficient stove is of no use if it is going to take six hours instead of
the usual two hours to cook the meal! But there was a very simple solution
to this problem too - introduce multiple tunnels in the biomass. I made one
design with three L shaped tunnels in the biomass and it worked beautifully.
Of course this made the stoking up operation a bit more complicated.
During these experiments I discovered one more problem with this type
of stoves. As the description of the stove operation reveals, this is a
nonreplenishable stove. Once the cooking process is started, it is not
possible to add to the fuel mass. On the other hand, the air flow through the
stove, which governs the combustion process is dependent on the dimensions of
the L shaped tunnel. But as the tunnel boundary itself burns and moves back
the tunnel dimensions change with time. So how does one ensure a reasonably
uniform rate of energy output? I may be getting very high energy output for a
short duration during the stove operation leading to a high overall efficiency
value, but for most of the time the efficiency actually may be very low.
Therefore I devised a method that gave me the information regarding the
variation in the energy input as well as the useful energy output with time.
The method is described below. It was later published in the paper entitled
'An Efficiency Test for Nonreplenishable Cookstoves' by Priyadarshini Karve
et al., Proceedings of the National Workshop on Renewable Energy: Improved
Chulha, Kiln and Other Related Devices (Dec 1993, Bhubaneshwar, India), p.138.
1. Calorific value of the biomass is determined using the bomb calorimeter.
2. Two identical flat bottom cylindrical aluminium cooking pots of
appropriate size with close fitting aluminium lids are used. Each lid has a
hole at the center through which a thermometer can be inserted.
3. Each pot is filled with a known volume of water (about 2/3 of the pot
capacity).
4. The stove, stoked with a known mass of fuel, is kept on a balance and is
ignited. The mass of stove+fuel is noted. One pot, with the lid and
thermometer, is kept on it after noting the initial temperature of the water.
The start time is also noted.
5. When the temperature of the water reaches 80 deg. C, the pot is replaced
by the second pot. Before putting on the second pot, the mass of stove+fuel
and the end time of the turn is noted.
6. The first pot is emptied and refilled with water at room temperature.
7. When the temperature of the water in the second pot reaches 80 deg.C, the
procedure is repeated. This goes on till the fire dies out.

Input energy of each turn = Mass of biomass burnt during the turn X Calorific
value
Output energy of each turn = Volume of water X Rise in water temperature

Therefore efficiency of each turn can be calculated. Knowing the time
taken for each turn a graph of output energy or efficiency against time can
be plotted. The average of efficiencies over all the turns gives the overall
efficiency.
There is one flaw in this method. As the stove operation progresses,
the biomass itself undergoes chemical changes and the calorific value is not
really a constant. But then this flaw is common to all efficiency tests.
I found that for the 'Navjyoti' stove the efficiency of 30% resulted
for two different design configurations but the configuration with the
dimensions mentioned above gave the least variation in energy output with time.
I think the reason for the uniform energy output for this particular
tunnel design is due to the fact that the tunnel dimensions do not change
substantially during the cooking operation. In the earlier model, where the
flame was generated through burning of the biomass, as the boundary of the
tunnel burnt,it left behind a layer of ash. In order to maintain the flame
vigour it was necessary to tap the stove from time to time to make the ash
fall down and expose a new layer of biomass. In my improved design, the first
few layers of the boundary of the tunnel did burn, but during this period, the
inner mass of biomass was first charred and then gasified and thereafter it
was mostly the gas that burnt. This also suggests that this type of design
can be used as a charcoal making stove or as a gasifier. But dense packing of
biomass is the critical factor here and that may be difficult with biomass
types other than sawdust. I found that the efficiency dropped to about 26% and
there was some smoke emission when leaf litter was used instead of sawdust.
I later discovered that the idea of introducing multiple tunnels in
the densely packed fuel mass to make multiple mini gasifiers had already been
used by Dr. Grover in his char briquette design. My work had demonstrated that
it works very well with raw biomass too.
Priyadarshini Karve.

 

From gpk at physics.unipune.ernet.in Sat Mar 28 02:28:03 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:51 2004
Subject: Answer to AWL's queries-2
In-Reply-To: <199803271214.PAA25842@ns.alkor.ru>
Message-ID: <Pine.SOL.3.96.980328125439.15536C-100000@physics>

Dear Dr. Judkevitch,
It is interesting that you mention aluminium salts. I did not know
that these had a catalytic effect in combustion. I will find out what are
the chemical ingredients of vertisol.
Since Dr. Larson wrote about your charcoal making method, I had
wanted to get in touch with you. In my next communication I will describe
what I have tried in that direction and then perhaps we can discuss this
matter further.
Thank you.
Priyadarshini Karve.

On Fri, 27 Mar 1998, Woodcoal wrote:

>
> Dear Karve
> I think, in your work the most interesting this use of clay. It is
> important to know structure of clay. Probably there there are a lot of
> salts of aluminium, which helps complete combustion (kataliz). If such
> pellets (cylinders or spheres) to heat up without oxygen the good coal for
> household furnaces can turn out. I would like to recommend you our
> technology for reception coal. It cheap, simply also does not give harmful
> gases. About it you were written of the Dr. Larson .
>
> Sincerely Jury Judkevitch (Rossia)
> ----------
> > Îò: Priyadarshini Karve(SBO) <gpk@physics.unipune.ernet.in>
> > Êîìó: stoves@crest.org
> > Òåìà: Answer to AWL's queries-2
> > Äàòà: 27 ìàðòà 1998 ã. 21:08
> >
> >
>

 

 

From larcon at sni.net Sat Mar 28 20:03:01 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Forwarded: Question on Activated Carbon
Message-ID: <v01540b00b141dce826f0@[204.133.251.10]>

(RWL): Stovers: Can anyone answer this authoritatively? I know
almost nothing, as is clearly demonstrated below.

Lee_thian_soong: My understanding is that the difference is that
activated charcoal is made in special (and secret) ways to increase the
absorptivity. I think that you should be able to use regular charcoal
safely if it was made from natural materials (some briquettes contain a lot
of coal and who knows what else). I would start with a small test, and
would change the charcoal much more often. You certainly can dry out the
charcoal and perhaps can find some way to reuse it if it is of sufficiently
large size. We have been discussing making briquettes by adding clay - and
I suggest looking at our archives for those ideas. I suppose the size of
the particles should be matched as well as you can with the commercial
activated charcoal. Best of luck. Ron

To new member Sandeep Saxena: I just read your good response to
Piyadarshini, where you mentioned hearing a lecture by P.D. Grover on
activated charcoal - can you (or anyone) add anything on how to make your
own?

(From Lee_thian_soong):

Dear Mr Larson,

I am building a biological filter for my fish pond with a very small
budget. Activated carbon is quite expensive in Malaysia. Can I use charcoal
as a replacement of activated carbon for my biological filter?

Thank you for your attention.

Regards,
lee_thian_soong@simenet.com

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

 

 

From larcon at sni.net Sun Mar 29 01:04:57 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Forwarded: Question on Activated Carbon
Message-ID: <v01540b01b1435bee6fc0@[204.133.251.37]>

(RWL): Stovers: Can anyone answer this authoritatively? I know
almost nothing, as is clearly demonstrated below.

Lee_thian_soong: My understanding is that the difference is that
activated charcoal is made in special (and secret) ways to increase the
absorptivity. I think that you should be able to use regular charcoal
safely if it was made from natural materials (some briquettes contain a lot
of coal and who knows what else). I would start with a small test, and
would change the charcoal much more often. You certainly can dry out the
charcoal and perhaps can find some way to reuse it if it is of sufficiently
large size. We have been discussing making briquettes by adding clay - and
I suggest looking at our archives for those ideas. I suppose the size of
the particles should be matched as well as you can with the commercial
activated charcoal. Best of luck. Ron

To new member Sandeep Saxena: I just read your good response to
Piyadarshini, where you mentioned hearing a lecture by P.D. Grover on
activated charcoal - can you (or anyone) add anything on how to make your
own?

(From Lee_thian_soong):

Dear Mr Larson,

I am building a biological filter for my fish pond with a very small
budget. Activated carbon is quite expensive in Malaysia. Can I use charcoal
as a replacement of activated carbon for my biological filter?

Thank you for your attention.

Regards,
lee_thian_soong@simenet.com

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

 

 

From REEDTB at compuserve.com Sun Mar 29 17:08:05 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:35:51 2004
Subject: Stove preferences
Message-ID: <199803291714_MC2-384F-57D8@compuserve.com>

Dear Priyadarshini Karve:

I'm glad you are answering Larson's very detailed questions in installments
- non of us have infinite time to read mail, no matter how interesting.

You re-iterate a problem that has been discussed here at STOVES, many
times, ie the resistance of villagers to stoves different from what they
currently use. This group has focussed primarily on the technical question
of how to make a MUCH better WOOD-GAS (not WOOD) stove. We are all used to
"cooking with gas" (or electricity) where efficiency is high and we can
regulate cooking level from very high (2.5 kW) to get the water to a boil
to very low (0.2 kW) so as not to burn the food. We all presume that once
we achieve this goal at a reasonable price it will be possible to
disseminate the stove to those who will benefit from it. But you and many
others underline the resistance to new technology at the village level.

Here are comments on avenues to success:

1) Stove acceptance: In many cases the improvement in cooking claimed for
new WOOD stoves is marginal. We hope controllable, high intensity
wood-gas stoves will have such a clear advantage that they will be
accepted. After all, there seems to be no problem in accepting kerosene or
propane stoves - except cost.

2) Stove Distribution: I envisage a network of town distributors who go
into the countryside educating and selling to the housewife. They will have
to keep her happy with the product. Preferably there are some renwables
(such as briquette fuels) which he sells her, so makes money on them rather
than the initial installation.

We are all rightly skeptical of BIG GOVERNMENT "wisdom" and beneficence.
Ultimately private enterprise entrepeneurs should be compensated for
supplying improved products at a reasonable price, and they are willing to
work hard for it.

3) Smoke for insect control in thatched roofs: Light a smudgepot once a
day when no one is home. No one likes to or should breathe smoke. Leads
to emphesema and glaucoma. (Comments, Kirk Smith?) Look into beekeepers
smokers; simple, cheap and effective.

4) Smoke for mosquito control: use screens.

Comments?

Toward better cooking around the world.... TOM
REED

 

 

 

 

 

From larcon at sni.net Sun Mar 29 19:52:54 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Re(2): Forwarded: Question on Activated Carbon
Message-ID: <v01540b00b1442918b20d@[204.133.251.29]>

Stovers: This just in from Piet. I'd like also to hear from anyone
knowing "secrets" of making activated charcoal. Ron

Dear Ron,

The answer is YES. I have kept young gold carp alive for years using a
filter containing gravel and charcoal. I don't know how well activated or
other charcoal absorbs poisonous substances in aqueous solution. It might
be just a good base for active bacteria to settle on.

The best of luck to Mr Lee,

Piet Verhaart

At 19:20 28/03/98 -0600, you wrote:
> (RWL): Stovers: Can anyone answer this authoritatively? I know
>almost nothing, as is clearly demonstrated below.
>
> Lee_thian_soong: My understanding is that the difference is that
>activated charcoal is made in special (and secret) ways to increase the
>absorptivity. I think that you should be able to use regular charcoal
>safely if it was made from natural materials (some briquettes contain a lot
>of coal and who knows what else). I would start with a small test, and
>would change the charcoal much more often. You certainly can dry out the
>charcoal and perhaps can find some way to reuse it if it is of sufficiently
>large size. We have been discussing making briquettes by adding clay - and
>I suggest looking at our archives for those ideas. I suppose the size of
>the particles should be matched as well as you can with the commercial
>activated charcoal. Best of luck. Ron
>
> To new member Sandeep Saxena: I just read your good response to
>Piyadarshini, where you mentioned hearing a lecture by P.D. Grover on
>activated charcoal - can you (or anyone) add anything on how to make your
>own?
>
>(From Lee_thian_soong):
>
>Dear Mr Larson,
>
>I am building a biological filter for my fish pond with a very small
>budget. Activated carbon is quite expensive in Malaysia. Can I use charcoal
>as a replacement of activated carbon for my biological filter?
>
>Thank you for your attention.
>
>Regards,
>lee_thian_soong@simenet.com
>
>Ronal W. Larson, PhD
>21547 Mountsfield Dr.
>Golden, CO 80401, USA
>303/526-9629; FAX same with warning
>larcon@sni.net
>
>
>
>
Peter Verhaart, 6 McDonald St. Gracemere Q 4702 Australia
Phone: +61 7 4933 1761; fax: +61 7 4933 1761 or
+61 7 4933 2112 (when computer is on)
E-mail p.verhaart@cqu.edu.au

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

 

 

From elk at arcc.or.ke Mon Mar 30 10:16:26 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:35:51 2004
Subject: Sawdust Carbonisation- MkIII version ready for liftoff.
Message-ID: <199803301522.SAA08936@arcc.or.ke>

Stovers;

I've been rendered a bit quiet lately- it's because I'm in awe of
Priyadarshini Karve- her work and her eloquence. I think she'll be a pinch
of aluminium salts to this group. Welcome!

Tomorrow I fire up the ' modified Grover' sawdust carboniser. It's sitting
outside my office charged with a 73kg load of air-dried sawdust. I'll send
the appropriate photos to Alex (who's also been suspiciously quiet) and he
can replace a couple of the current photos of my MkII version.

Till later;

elk

----------------------------------------------------------------------------
-----------------------------------------
Elsen L. Karstad P.O. Box 24371 Nairobi Kenya. Fax (+254 2) 884437 Tel
884436, 882375
----------------------------------------------------------------------------
-----------------------------------------

 

 

From p.verhaart at cqu.edu.au Mon Mar 30 20:15:16 1998
From: p.verhaart at cqu.edu.au (P.Verhaart)
Date: Tue Aug 31 21:35:51 2004
Subject: Priyadarshini Karve-
Message-ID: <3.0.1.32.19980331112039.006a87dc@janus.cqu.edu.au>

Stovers;

Elsen Karstad said it, and I couldn't agree more.

"I've been rendered a bit quiet lately- it's because I'm in awe of
Priyadarshini Karve- her work and her eloquence. I think she'll be a pinch
of aluminium salts to this group. Welcome! "

Piet Verhaart
Peter Verhaart, 6 McDonald St. Gracemere Q 4702 Australia
Phone: +61 7 4933 1761; fax: +61 7 4933 1761 or
+61 7 4933 2112 (when computer is on)
E-mail p.verhaart@cqu.edu.au

 

From woodcoal at mailbox.alkor.ru Tue Mar 31 02:02:22 1998
From: woodcoal at mailbox.alkor.ru (Woodcoal)
Date: Tue Aug 31 21:35:51 2004
Subject: madam Karve makes good business
Message-ID: <199803310709.LAA29510@ns.alkor.ru>

Stovers!
I think madam Karve makes good business. Only 100 years back in Russia of
the furnace let out a smoke in the house. It at all illiteracy of peasants,
but economy. I could write many pages about the reasons it. There are
advantages for this system. These advantages can be unintelligible by the
one who lives in the rich country with a good climate. I think madam Karve
can find in the literature the answers to some questions. But I admire,
that she makes useful business and not having normal laboratory conditions.
I wish to her success and I shall be glad to help, if it is required.
Sincerely Jury Judkevitch

 

From gpk at physics.unipune.ernet.in Tue Mar 31 04:01:31 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:51 2004
Subject: answers to RWL's queries-3
Message-ID: <Pine.SOL.3.96.980331123855.9946A-200000@physics>

Dear Dr. Larson,
I had sent the attached mail on Saturday March 28. But it came back to
me with a message of mail failure. Therefore I am sending it again.
Sorry for the delay.
Priyadarshini Karve

 

Dear Dr. Larson,
Sorry for typing the wrong initials in the subject line of my
earlier communication.
I am aware that I am writing rather long communications. But the thing
is that till I quite accidently stumbled onto this discussion group, I had
been working without access to any really scientific information in this area.
I have gone through the archives here and I find that I am not familiar even
with the basic terminology. The ideas that I have used in my work are based
on some very rudimentary, highschool-level knowledge of the combustion
phenomenon. Therefore I request all of you to tell me whether I have been
going in the proper direction or not.
Thanks for your response so far. I will address the second batch of
queries a bit later.
Here are the details of my work on the biomass burning stove,
'Vanjyoti'. Some of this may be relevant to the charcoal making stove, though
I have not yet quite grasped the idea.
The basic design of the Vanjyoti stove consists of a metal drum. It
has a side opening near the bottom. A metal cylinder is attached to the side
opening, extending into the drum. Another cylinder is provided with the stove.
For stoking up the stove, the second cylinder is placed vertically at the
center of the drum. This cylinder and the fixed cylinder at the bottom form
an L shape. Biomass is packed into the empty space surrounding this L. Dense
packing of biomass is the key to proper operation of the stove. Consequently
it gives the best performance with densely packable fine particulate matter
like sawdust. Once the drum is packed with biomass, the central cylinder is
gently removed. This leaves an L shaped cavity in the biomass- the walls of
the horizontal arm of L are formed by the fixed cylinder at the bottom and
the walls of the vertical arm are made of the packed biomass itself. There is
a lid for the drum. It has an opening at the center, of the same diameter as
that of the L shaped tunnel. There are pot raisers on the lid so that when a
cooking pot is kept on the stove there is a gap between the top of the stove
and the bottom of the cooking pot. The fire is started by introducing a
burning stick from the side opening at the base of the vertical arm of the L.
The basic design has undergone many variations over the years. Perhaps all
of you already know of this under a different name. The particular model
that I studied in this work is called 'Navjyoti' (new flame). This design is
developed by the Technical Back up Support Unit at Indian Institute of
Technology, New Delhi and is claimed to be an improved design with an average
efficiency of 25%.
I observed this stove in operation and found that there was further
scope for improvement as there was a lot of smoke emission throughout the
stove operation.
The single most important factor that decides the completelness of
combustion is the air supply to the fuel mass and the air currents through
the stove also decide the flame direction. I did some theoretical
calculations based on a highly simplified analysis of the air flow dynamics
through the L shaped tunnel and juggled around with the tunnel dimensions. I
found a design that gave 30% efficiency as against the 25% claimed for the
Navjyoti model. According to my design, for the Navjyoti stove drum of height
33 cm and diameter 23 cm, the tunnel diameter should be 4 cm (as against
7.5 cm recommended by Navjyoti designers) and the pot raiser height should be
2 cm (as against the recommended 1 cm). With these design modifications, I
could see that mostly gas was coming out from the top of the stove, it was
getting ignited due to the secondary air below the cooking pot and there was
a blue flame suspended there on top of the L shaped tunnel. At the same time
I also realised why the IIT designers had not recommended these stove
dimensions. The power output rating of my improved design was very very low.
An efficient stove is of no use if it is going to take six hours instead of
the usual two hours to cook the meal! But there was a very simple solution
to this problem too - introduce multiple tunnels in the biomass. I made one
design with three L shaped tunnels in the biomass and it worked beautifully.
Of course this made the stoking up operation a bit more complicated.
During these experiments I discovered one more problem with this type
of stoves. As the description of the stove operation reveals, this is a
nonreplenishable stove. Once the cooking process is started, it is not
possible to add to the fuel mass. On the other hand, the air flow through the
stove, which governs the combustion process is dependent on the dimensions of
the L shaped tunnel. But as the tunnel boundary itself burns and moves back
the tunnel dimensions change with time. So how does one ensure a reasonably
uniform rate of energy output? I may be getting very high energy output for a
short duration during the stove operation leading to a high overall efficiency
value, but for most of the time the efficiency actually may be very low.
Therefore I devised a method that gave me the information regarding the
variation in the energy input as well as the useful energy output with time.
The method is described below. It was later published in the paper entitled
'An Efficiency Test for Nonreplenishable Cookstoves' by Priyadarshini Karve
et al., Proceedings of the National Workshop on Renewable Energy: Improved
Chulha, Kiln and Other Related Devices (Dec 1993, Bhubaneshwar, India), p.138.
1. Calorific value of the biomass is determined using the bomb calorimeter.
2. Two identical flat bottom cylindrical aluminium cooking pots of
appropriate size with close fitting aluminium lids are used. Each lid has a
hole at the center through which a thermometer can be inserted.
3. Each pot is filled with a known volume of water (about 2/3 of the pot
capacity).
4. The stove, stoked with a known mass of fuel, is kept on a balance and is
ignited. The mass of stove+fuel is noted. One pot, with the lid and
thermometer, is kept on it after noting the initial temperature of the water.
The start time is also noted.
5. When the temperature of the water reaches 80 deg. C, the pot is replaced
by the second pot. Before putting on the second pot, the mass of stove+fuel
and the end time of the turn is noted.
6. The first pot is emptied and refilled with water at room temperature.
7. When the temperature of the water in the second pot reaches 80 deg.C, the
procedure is repeated. This goes on till the fire dies out.

Input energy of each turn = Mass of biomass burnt during the turn X Calorific
value
Output energy of each turn = Volume of water X Rise in water temperature

Therefore efficiency of each turn can be calculated. Knowing the time
taken for each turn a graph of output energy or efficiency against time can
be plotted. The average of efficiencies over all the turns gives the overall
efficiency.
There is one flaw in this method. As the stove operation progresses,
the biomass itself undergoes chemical changes and the calorific value is not
really a constant. But then this flaw is common to all efficiency tests.
I found that for the 'Navjyoti' stove the efficiency of 30% resulted
for two different design configurations but the configuration with the
dimensions mentioned above gave the least variation in energy output with time.
I think the reason for the uniform energy output for this particular
tunnel design is due to the fact that the tunnel dimensions do not change
substantially during the cooking operation. In the earlier model, where the
flame was generated through burning of the biomass, as the boundary of the
tunnel burnt,it left behind a layer of ash. In order to maintain the flame
vigour it was necessary to tap the stove from time to time to make the ash
fall down and expose a new layer of biomass. In my improved design, the first
few layers of the boundary of the tunnel did burn, but during this period, the
inner mass of biomass was first charred and then gasified and thereafter it
was mostly the gas that burnt. This also suggests that this type of design
can be used as a charcoal making stove or as a gasifier. But dense packing of
biomass is the critical factor here and that may be difficult with biomass
types other than sawdust. I found that the efficiency dropped to about 26% and
there was some smoke emission when leaf litter was used instead of sawdust.
I later discovered that the idea of introducing multiple tunnels in
the densely packed fuel mass to make multiple mini gasifiers had already been
used by Dr. Grover in his char briquette design. My work had demonstrated that
it works very well with raw biomass too.
Priyadarshini Karve.

 

From gpk at physics.unipune.ernet.in Tue Mar 31 04:03:32 1998
From: gpk at physics.unipune.ernet.in (Priyadarshini Karve(SBO))
Date: Tue Aug 31 21:35:51 2004
Subject: Answers to RWL's queries-4
Message-ID: <Pine.SOL.3.96.980331125136.10039A-200000@physics>

 

Dear Dr. Larson,
Finally I come to the last batch of questions - mainly on char
briquettes from sugarcane trash.
I have recieved a few suggestions that chopping up the sugarcane leaves
before charring may work. But chopping up dry leaves of sugarcane is not an
easy task at least for manually operated choppers. In fact, the reason I first
thought of charring was that it is easier to convert the char into particulate
briquettable matter!
I am also rather bewildered about this business of flaring or venting
of pyrolysis gases. What we have done using a steel barrel is much simpler
than the charcoal making stoves that you seem to have used. And yet with this
rather crude and simple technique, we are getting a remarkably high char
output (40-50% of the total biomass filled into the barrel). The only problem
is that the rate of charring is very low.
We just fill up the barrel (of 10 kg capacity) with the sugarcane
trash, get a fire going onto a mud platform (using some trash itself), and
then invert the barrel onto the fire. Iron pipes have been inserted into the
platform to supply air to the fire. The platform to barrel joint is completely
sealed off with mud. The mouths of the aerator pipes are left open for about
five minutes or so to ensure that the fire spreads throughout the barrel and
then these too are sealed off. Once the air supply is cut off, the fire slowly
dies down but the heat generated charrs the remaining biomass. When we open
the barrel after about 8 hours or so, we find a smouldering mass of char. This
is easily crushed into char powder with the help of a roller. The char thus
obtained is made into a dough by adding water and binder. I have tried the
mucilage of okra plant and a mixture of clay and okra mucilage as binders. I
found that unlike the biomass briquettes, the type of binder in the char
briquettes is of no consequence to the combustion process, but more than 10%
clay degrades the combustion characteristic of the briquettes. The briquettes
are made using a hand operated mould and sun dried.
While dense packing of material is the criticial requirement of your
charcoal making stoves, I think the loose paking of the sugarcane trash is the
key to the success of our kiln. The randomly distributed air pockets in the
biomass filled into the barrel help in spreading the fire throughout the
barrel. I do not really know why we are getting such a high biomass to char
conversion efficiency. One important factor may be the moisture content of the
trash. The experiments are being conducted in a low rainfall area with hot
and dry climate. The sugarcane trash as collected from the farms is quite dry,
and before we actually use it, it further dries out for a month or so in the
scorching sunlight.
I started off the project with the intention of making Grover
briquettes. This is basically a 'cake', 13 cm in diamter and 7 cm in height.
There are 19 vertical tunnels in the cake, of 1.2 cm diameter each. There is a
special mould for making these briquettes. I have seen this briqette in
operation. One can see 19 tiny blue flames suspended above the 19 holes. But
I soon realised that this is not a practical design for a domestic fuel. This
briquette has become very popular in states like Himachal Pradesh where it is
mainly used for room heating as a substitute for charcoal. It is burnt in an
ordinary charcoal burning stove- what is popularly called 'Angithi' in India.
The dimensions of the briquette have been optimised mainly for this stove. But
cookstoves come in different shapes and sizes depending on the eating habits
and family sizes.
One point I must clarify here. I am looking towards these briquettes
as an alternative to fuelwood and not as an alternative to charcoal. No
ordinary villager in Maharashtra uses charcoal for domestic cooking. The
fuelwood is available free of cost. Of course one person per family spends
the entire day in collecting fuelwood so it means the loss of one person's
daily wages. But a villager does not necessarily associate waste of time with
loss of money. This is another reason why it is necessary to keep the trash
to briquette conversion process as simple as possible and therefore I am
reluctant to introduce an additional chopping operation before charring. The
fuel, however better it may be as compared to wood, will not be accepted by
the rural housewife if it costs more that 2 to 3 rupees per kg (1 dollar =
35-40 rupees). As far as the sugarcane farmer is concerned, he has already
found a solution to his problem- he just burns off the trash in open air. He
will not take the trouble of doing all this processing (or collecting and
selling the trash to a briquette maker) unless he (as well as the briquette
maker) sees some profit in it.
Coming back to the problem of Grover briquette, one can of course
make different moulds so that the briquettes can be made in different sizes,
but that is an additional expense for the briquette maker. On the other hand,
the Grover design is really the best possible way of using char briquettes. So
I solved the problem by making cylindrical stick briquettes using a ram press.
The sticks, if made to stand vertically with the sides in contact with each
other, simulate the shape of the Grover briquette- compacted mass of char
separated by an array of tunnels. The sticks can be stacked in a stove of any
size and shape. Alternatively, they can also be used with random stacking as
in the case of charcoal or fuelwood. Our stick briquettes are about 2 cm in
diameter and the height is about 10 cm. The burning performance is not as good
as the Grover briquette, but with the flexibility in shape and size, the
acceptability of the briqettes as domestic fuel has definately increased.
So the problem is precisely this: What is the simplest, cheapest and
fastest possible process to make the trash to char briquette conversion? And
yet the briquettes must be closer to charcoal than wood in performance as
domestic fuel. This is something like a saying that we have in Maharashtra:
I need a cow that gives me a lot of milk and also has a mild disposition!
I had mentioned the idea of pushing bundles of sugarcane trash through
a heated metal pipe. Our preliminary experiments now show that the idea works.
Surronding the entire pipe with burning trash did not work very well as the
trash inside the pipe also tended to catch fire. Then we used two biomass
burning stoves with the trash itself as fuel, balanced a steel pipe on these
two stoves, inserted the trash from one end and char did come out of the other
end. Of course, the hot char catches fire as soon as it comes out, but this
problem can be solved by sprinkling water onto the outcoming char. More
experiments will have to be conducted to find out how efficient and how fast
the process can be.
To answer the query about cleanliness results: We have not really
given much thought to the pollution resulting from cookstoves apart from
trying to reduce the visible soot and smoke emission. One reason for this is
that we do not have any gas sensors/analysers to conduct that type of
research. So far, the most sophisticated instrument that we have is the Bomb
calorimeter!
And Finally a few lines about my work on artificial synthesis of
diamond: The process has been known since 1950's and yes I have been
successful in making diamonds. The basic concept is that if one has carbon
atoms derived from any ordinary source of carbon and one creates local
conditions such that the atoms are forced to form the metastable diamond
structure rather than the stable graphite, then one would end up with an
artificial process of making diamond crystals. The process I use involves
thermal decomposition of hydrogen and methane (which is the carbon source)
under vacuum. The hydrogen environment provids the diamond-favourable
conditions. The diamond thus formed is in the form of a polycrystalline
coating with each crystal of the size of a few microns. So it is useless as a
piece of jwellery, but has a lot of applications in industry, especialy as a
cutting tool.

Priyadarshini Karve.

 

From elk at arcc.or.ke Tue Mar 31 07:32:38 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:35:51 2004
Subject: Carbonising Sawdust- Gover Mod. MkII
Message-ID: <v01510100b146b2d44682@[199.2.222.136]>

Stovers;

Meltdown. The large prototype carboniser (made of two 200 litre drums
stacked vertically end-to-end, as previously described) started off well,
with the first half hour's burn proving that the unit can be
self-sustaining after initial heating using firewood. After half an hour,
the heat generated from the flaring volatiles entering the central chimney
through perforations below the firewood grill was intense enough to distort
the walls of the chimney (made of 2mm mild steel sheet) and the grill
itself (3mm perforated steel plate).

Primary air was controlled via a valve at the bottom of the chimney, and
when this was set at anything over 25% open, the flaring gasses inside the
chimney roared like a muted jet engine.

After one hour's operation, the everything seemed to be out of control. The
heat was intense, flames shot up out of the top of the unit, smoke vented
at pressure from the side filler hopper and occasionally flared causing 2 m
high jets of flame accompanied by burning particles of sawdust.

Obviously the whole process needs to be controlled at a more sedate pace
with heat retained in the lower half of the pyrolyser. When the sawdust
near the top is in contact with a nearly red-hot chimney wall volatiles are
created too distant from the lower vent to escape down- hence are forced up
& the mini Vesuvius effect results.

Carbonised sawdust was produced, but I emptied the pyrolyser before the
73kg batch was completely carbonised in order to salvage the machine; over
half (by volume) of product was only partially carbonised.

This work is coming at Priyadarshini Karve's investigations from the
opposite approach. I've developed a bomb that needs to be tamed & slowed
down now. We need to work towards the middle ground. Suggestions? Maybe I
should install a second (exhaust valve) near the top of the chimney & try
to regulate heat/volatiles production in this manner. Or a heat sink
jacket of some type... any use for masses of boiling hot water?

A question for Thomas Reed: How much heat is released within 2 hours by the
carbonisation of 73 kg of air-dry sawdust assuming a mere 15% charcoal
recovery (based on my previous work with the smaller unit)? It's pretty
impressive to experience.

I'll send Alex some pictures tonight.

elk

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
______________________________

 

 

From tmiles at teleport.com Tue Mar 31 18:09:53 1998
From: tmiles at teleport.com (Tom Miles)
Date: Tue Aug 31 21:35:51 2004
Subject: No Attachments Please
Message-ID: <199803312316.PAA12414@radius1.teleport.com>

Bioenergy List Members:

Please do not attach files or images to your messages.

Attachments cause complications for the list users and administrators.

Rather, invite those who are interested to request and receive a file or image from you directly. Alternatively, post a file or image on your own website or ftp site.

Thank you

Tom Miles
Bioenergy List Administrator

------------------------------------------------------------------------------
Thomas R. Miles tmiles@teleport.com
Technical Consultants, Inc. Tel (503) 292-0107/646-1198
1470 SW Woodward Way Fax (503) 605-0208
Portland, Oregon, USA 97225

 

From english at adan.kingston.net Tue Mar 31 19:10:09 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:51 2004
Subject: Elsen's Pictures
Message-ID: <199804010016.TAA26382@adan.kingston.net>

Dear Stovers,
Elsen's latest efforts are preserved for inspection in the 'New'
section at the address shown below.

Suspiciously yours, Alex
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Web Site http://www1.kingston.net/~english/Stoves.html

 

From english at adan.kingston.net Tue Mar 31 19:10:11 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:35:51 2004
Subject: Answers to RWL's queries-4
Message-ID: <199804010016.TAA26386@adan.kingston.net>

 

Dear Priyadarshini Karve,

On the subject of carbonizing dry sugarcane leaves;
I would like to encourage you to try the method that is refered to
in the archives under many different names. I'll refer to it as the
toplite carbonizer. Most of us have focused on wood but I have on a
couple of occasions used dry hay. I didn't have much luck flaring
the gasses but the carbonizing process worked well as judged by the
appearance of the hay.

I suspect that packing (with hands or feet) an oil drum or even a big
hole in the ground with the dry leaves would work as well as the
smaller containers that I have used when ignited on top. I am not
sure if any additional air would be required. If so, it can be
introduced from the top using a sheet metal cone (slightly smaller
diameter than the barrel or pit) sitting on the packed leaves. The
smoke will rise up and out the small hole in the top of the cone,
where it might hopefully be flared. The air will drop down into the
leaves around the outside of the cone. This is roughly shown in the
bottom half of the drawing at
http://www1.kingston.net/~english/Alex.htm
It sound as though you have the right climate for this.

As you probably know, one of the problems with packing these kinds
of materials is that they behave like a spring. As soon as you take
the pressure off, up it comes. If the container has a bit of a neck
or narrowing on top, then the material will stay in as more is
added. This will only help for smaller diameter containers, perhaps no
bigger than an 55 gallon oil drum. I am not sure.
Wedges along the sides would also help and are used in baling
machines.

I am very pleased to hear of your work, and encourage you to send me
some pictures and drawings to be referenced by the list members at
the site addressed below.

Alex English

> Dear Dr. Larson,
> Finally I come to the last batch of questions - mainly on char
> briquettes from sugarcane trash.
> I have recieved a few suggestions that chopping up the sugarcane leaves
> before charring may work. But chopping up dry leaves of sugarcane is not an
> easy task at least for manually operated choppers. In fact, the reason I first
> thought of charring was that it is easier to convert the char into particulate
> briquettable matter!
> I am also rather bewildered about this business of flaring or venting
<snip>
> Priyadarshini Karve.
>
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Web Site http://www1.kingston.net/~english/Stoves.html

 

From larcon at sni.net Tue Mar 31 22:13:27 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Re(2): Carbonising Sawdust- Grover Mod. MkII
Message-ID: <v01540b07b146fcafb41d@[204.133.251.15]>

Elsen - Sorry to hear of the "bomb". Some ideas below.

(Elsen):
> (snip> I've developed a bomb that needs to be tamed & slowed
>down now. We need to work towards the middle ground. Suggestions? Maybe I
>should install a second (exhaust valve) near the top of the chimney & try
>to regulate heat/volatiles production in this manner.

(RWL): I would guess that the uppermost holes will tend to have
more moisture - but this may be good. I don't see any real problem - as
the heat released there will do less heating and I guess this is desirable.

> Or a heat sink
>jacket of some type... any use for masses of boiling hot water?

(RWL): There are people recently proposing steam engines on the
bionergy list - at costs supposedly around $1 per watt - well less than PV.

If you can vaporize and condense to give distilled water - you may
find it very valuable for hospitals and such.

For just making the water more healthful - this might make sense as
well in some locations - or for cooking.

>
>A question for Thomas Reed: How much heat is released within 2 hours by the
>carbonisation of 73 kg of air-dry sawdust assuming a mere 15% charcoal
>recovery (based on my previous work with the smaller unit)? It's pretty
>impressive to experience.

(RWL): I'll address this as well as looking for Tom's further
input. If all of the biomass were consumed, you would have about a 200 kW
system (78 kg * 18 MegaJoule/kg / 7200 seconds, and 1 Watt = 1 J/sec). If
you saved 15% charcoal with an energy content of 30 MJ/kg, you are losing
(or getting) just about 25% by energy, so you would drop to 150 kW. In
your case, it sounds like you were less than 100 kW.
>
>I'll send Alex some pictures tonight.
>
>elk

(RWL): I look forward to your pictures. Since the basic issue is
how to use the sawdust productively, I think the answer may be to make the
"Priyadarshini" sawdust balls for use in your one-can design - with its 3:1
turndown controllability ratio already. You will have productive heat
capture and a better conversion rate for the sawdust to charcoal as well.
The problem used to be making long cylindrical sawdust briquettes, but
(hopefully - still no proof) the balls will work as well or better in these
top-lit stoves. And maybe the balls can be made almost as fast or faster
than extrusion. Maybe the stove users will trade you back "used" charcoal
balls for sawdust balls - and maybe then your production costs can go down
(and the charcoal balls maybe already have the right amount of clay). The
problem with this dream scenario is the two-way transportation of new and
"used" balls. Better if we can design a tough enough "used" ball so that
it will have user approval for charcoal cooking. I doubt this last step.

Here's hoping 1) sawdust balls can replace wood branches in
charcoal-making stoves, and 2) that the "used" balls can be easily
densified into higher quality charcoal briquettes.

The big gains would be in 1) much cleaner cooking and 2) consuming
fewer trees both for making (badly) regular charcoal and for cooking.

Regards Ron

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

 

 

From larcon at sni.net Tue Mar 31 23:18:19 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Forwarding Duke on "Living Dangerously - Carbonising Sawdust"
Message-ID: <v01540b01b14768e5ffda@[204.133.251.13]>

Stovers: I don't think Tom Duke would mind my sending this personal note
on to the full group. In closing, I add another of Tom's from a week ago.
Both have to do mostly with Elsen's charcoaling of sawdust.
I should note that Tom was the first person I know of from 2 years
ago to try charcoal making stoves - and very successfully in two clever
forms - 1) a very tall form for heating a barn and 2) one using just two
parallel vertical holes in the ground with (pluggable) air supply paths
between. This last is a zero-cost stove idea that needs more work.

>Hi Ron,
>
>I am also concerned about these experements with sawdust. However, it has
>brought to mind a
>question that arose very early in these discussions. It was pointed out
>that liquid fuels are
>better accepted. So, I am asking this: "In what ways might we make liquid
>fuels, and other
>chemicals from sawdust while we are making charcoal?"

(RWL): In the early charcoal literature from the last century,
there is a great deal of emphasis to getting liquid fuels and chemicals (by
condensing the pyrolysis gases). I think Tom Duke asks a good question,
but I am not a good one to answer this question. I have been assuming -
maybe incorrectly - that cook stove operators would have a bit of
difficulty doing anything at the household level.

Tom - I have a feeling you may have been working on this. Do you
have anything to report?
>
>Also another valid question about what to do with the heat? So, I ask: "In
>what ways might we use
>heat?"
>
>Sincerely,
>
>Tom Duke <tduke@igc.apc.org>
>Burlington, IA

(RWL): The ones I like best (with single family cook stoves coming
first) are:
brick making
bakeries
ceramics kilns

When we get a good cheap reliable Stirling engine, then there
should be lots of other possibilities. At bigger scales, there are
probably many places where steam engines or turbines may already work.

Tom - what are yours?

Now the Tom Duke message from two weeks ago -

>Hi Ron,
>
>This problem is similar to crop drying! In our continuous-flow corn dryers
>we have similar
>problems of material flow and temperture control. A thoughtful look at a
>corn (grain) dryer of
>the flow-through type vs. batch type could give significant insight.

(RWL): "This problem" refers to Elsen's flow blockages and the
occasional "blowup". I am sure that Tom has a great deal of knowledge on
crop drying (Tom being a farmer - specializing in all sorts of renewable
aspects of farming), and I guess I was waiting until I could look up the
crop-drying hardware topic a bit - for Elsen's benefit.

Does Tom or anyone have a few ideas on how to do anything new? I
think the latest message from Elsen shows that the charcoaling operation
raises the material handling technology issue to a very difficult level.
But Tom is undoubtedly correct that there are similarities in technologies
that we should explore.

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

 

 

From larcon at sni.net Tue Mar 31 23:18:35 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:35:51 2004
Subject: Re(RWL-4A): Answers to RWL's queries-4
Message-ID: <v01540b02b14769cd3637@[204.133.251.13]>

Priyadarshini and other stovers:

(RWL): I seemed to have shipped off into the "void" my answers to
your response #3. If anyone received these, I hope that will ship them
back to me or the "stoves" system. I'll start over on comments on your #3
answers in a few days, if I don't hear.

Priyadarshini - 1:
>Dear Dr. Larson,
> Finally I come to the last batch of questions - mainly on char
>briquettes from sugarcane trash.
> I have recieved a few suggestions that chopping up the sugarcane leaves
>before charring may work. But chopping up dry leaves of sugarcane is not an
>easy task at least for manually operated choppers. In fact, the reason I first
>thought of charring was that it is easier to convert the char into particulate
>briquettable matter!

(RWL - 1): Sorry for having so many questions. But you have given
great insight and have offered several new topics to work on. I think that
getting the maximum positive use from small biomass pieces is a very
important stoves problem. I hope that anyone with suggestions to offer
will jump in. I am afraid I do not yet have a good idea, and I can see that
chopping would not be desirable. See more below.

Priyadarshini-2:
> I am also rather bewildered about this business of flaring or venting
>of pyrolysis gases. What we have done using a steel barrel is much simpler
>than the charcoal making stoves that you seem to have used.

(RWL-2): Our (the charcoal-making stove group here) emphasis has
been equally on using the pyrolysis gases for cooking and for making
charcoal. I think one issue now is how to get some productive use from
those gases in the simpler method you describe below. Another is how to
speed that process up.

Priyadarshini -3: >And yet with this
>rather crude and simple technique, we are getting a remarkably high char
>output (40-50% of the total biomass filled into the barrel). The only problem
>is that the rate of charring is very low.

(RWL-3): Flaring is better than venting both to reduce the
greenhouse gas emissions and presumably for local health reasons as well.
However, in rereading this, it sounds like you (in some versions) are
neither venting nor flaring - which is quite remarkable.

Priyadarshini -4:
> We just fill up the barrel (of 10 kg capacity) with the sugarcane
>trash, get a fire going onto a mud platform (using some trash itself), and
>then invert the barrel onto the fire. Iron pipes have been inserted into the
>platform to supply air to the fire. The platform to barrel joint is completely
>sealed off with mud. The mouths of the aerator pipes are left open for about
>five minutes or so to ensure that the fire spreads throughout the barrel and
>then these too are sealed off.

(RWL -4): Is it true that very little exhaust gases are vented to
the atmosphere during this five minute period (or later)?
How high up into the can do these aerator pipes extend?

Priyadarshini-5:
>Once the air supply is cut off, the fire slowly
>dies down but the heat generated chars the remaining biomass. When we open
>the barrel after about 8 hours or so, we find a smouldering mass of char. This
>is easily crushed into char powder with the help of a roller. The char thus
>obtained is made into a dough by adding water and binder. I have tried the
>mucilage of okra plant and a mixture of clay and okra mucilage as binders. I
>found that unlike the biomass briquettes, the type of binder in the char
>briquettes is of no consequence to the combustion process, but more than 10%
>clay degrades the combustion characteristic of the briquettes. The briquettes
>are made using a hand operated mould and sun dried.

(RWL-5): 1. Are you still doing these tests?
2. I wonder if you believe some pyrolysis gases are escaping
through the seal (or through the base) and whether there is some way to
test for those - such as with a match.
3. Do you see any evidence of condensation of liquids?
4. Mike Antal on our list has described a patented charcoaling
system with charcoal yields (40-50%) like yours. I don't understand his
approach but it is pressurized I believe - and much faster. There may be
some correlations.

Priyadarshini-6:
> While dense packing of material is the critical requirement of your
>charcoal making stoves, I think the loose packing of the sugarcane trash is the
>key to the success of our kiln. The randomly distributed air pockets in the
>biomass filled into the barrel help in spreading the fire throughout the
>barrel. I do not really know why we are getting such a high biomass to char
>conversion efficiency. One important factor may be the moisture content of the
>trash. The experiments are being conducted in a low rainfall area with hot
>and dry climate. The sugarcane trash as collected from the farms is quite dry,
>and before we actually use it, it further dries out for a month or so in the
>scorching sunlight.

(RWL-6):
1. Tom Reed has reported that the pyrolysis process is mildly
exothermic, once begun. I think it would be interesting to see the
temperature vs time profile for various places in your inverted can. I am
guessing that it is not just the heat from your initial burning that allows
this process to work. Do you have or could you get access to a few
thermocouples?
2. Any modelers out there want to predict the shape of the T-t
diagrams for a can with 10 Kg of material over 8 hours?
3. Have you tried this approach with different size containers?;
with insulation outside the metal can?
4. The tight packing in our charcoal-making stoves is to ensure a
small but uniform primary air flow - whereas you want none,

Priyadarshini-7:
> I started off the project with the intention of making Grover
>briquettes. <snip> But
>I soon realised that this is not a practical design for a domestic fuel.
>> > <snip> I am looking towards these briquettes
>as an alternative to fuelwood and not as an alternative to charcoal.
> <snip> The
>fuel, however better it may be as compared to wood, will not be accepted by
>the rural housewife if it costs more that 2 to 3 rupees per kg (1 dollar =
>35-40 rupees).
> <snip> . So
>I solved the problem by making cylindrical stick briquettes using a ram press.

(RWL-8): 1. I believe that you are now talking about turning the
charcoal from the trash-to-charcoal operation into briquettes (not 1)
directly trash to briquette, because you have not yet found a way to do
that, nor 2) directly cleanly combusting trash - is that correct?
2. This conclusion is the same as that of Karstad - turn sawdust
to charcoal - then turn the loose charcoal into stick briquettes.
3. When I get excited about "sawdust balls", I am thinking of
making charcoal (while cooking). But the direct clean use of trash (in any
conversion process) should also be our goal - see below also. In our
charcoal-making stove designs there is a significant pressure gradient
through the bed of to-be-pyrolyzed material that would not be present in
typical charcoal burning designs. Thus spherical charcoal balls in your
stick charcoal burner might not work due to their greater flow resistance
compared to sticks. But I'd like to know if charcoal spheres are as good
as charcoal sticks.
4. Your cost goals are exceedingly difficult!!

Priyadarshini-8:
>The sticks, if made to stand vertically with the sides in contact with each
>other, simulate the shape of the Grover briquette- compacted mass of char
>separated by an array of tunnels. The sticks can be stacked in a stove of any
>size and shape. Alternatively, they can also be used with random stacking as
>in the case of charcoal or fuelwood.

(RWL-8): 1. Do you see any difference in combustion with the
means of, and orientation of, stacking your charcoal sticks? (We find
vertical stacking to be much better - to get tight stacking)
2. Paul Hait of our list has done a lot of work on the appropriate
spacing and air supply for the standard US "pillow" shaped charcoal
briquette. He strives for ensuring that radiation losses are predominantly
upward. He wants radiation to generally strike other charcoal if not
intercepting a cook pot (or meat in his usual application). He has added an
oven below to capture otherwise waste downward-directed radiation. He also
has emphasized the importance of reflector surfaces.

Priyadarshini-9:
>Our stick briquettes are about 2 cm in
>diameter and the height is about 10 cm. The burning performance is not as good
>as the Grover briquette, but with the flexibility in shape and size, the
>acceptability of the briqettes as domestic fuel has definately increased.

(RWL-9): 1. What do you mean when you say that the burning
performance is not as good? More smoke? Less power? Greater variation
with time?
2. How does your stick height of 10 cm compare to the Grover
briquette height?
3. Do you light these on top or bottom?
4. Does the combustion (or degree of stick coverage) move downward
quickly or slowly?
5. Is the heat transfer to the cook vessel more by radiation or
hot gas convection?

Priyadarshini-10:
> So the problem is precisely this: What is the simplest, cheapest and
>fastest possible process to make the trash to char briquette conversion? And
>yet the briquettes must be closer to charcoal than wood in performance as
>domestic fuel. This is something like a saying that we have in Maharashtra:
>I need a cow that gives me a lot of milk and also has a mild disposition!

(RWL-10): 1. Cost, performance, and I would add the environment
(The Maharashtra cow should cause no health problems).
2. Perhaps we should be trying again the "Grover-style" pyrolyzer
that Elsen has been recently describing. Elsen's modification is to
achieve continuous feedthrough. If we strove for an outer "donut" filled
with batch trash, then maybe we could continue to use something like the
present charcoal-making design. Maybe we could use a small amount of
sawdust balls but have a majority of the total energy coming from the outer
loose "trash". I don't think you should have to ignite any of this trash -
which can be pyrolyzed by the heat escaping radially from the upper or
lower cans. One difficulty will be in the sealing of this "trash can".

Priyadarshini-11:
> I had mentioned the idea of pushing bundles of sugarcane trash through
>a heated metal pipe. Our preliminary experiments now show that the idea works.
>Surrounding the entire pipe with burning trash did not work very well as the
>trash inside the pipe also tended to catch fire. Then we used two biomass
>burning stoves with the trash itself as fuel, balanced a steel pipe on these
>two stoves, inserted the trash from one end and char did come out of the other
>end. Of course, the hot char catches fire as soon as it comes out, but this
>problem can be solved by sprinkling water onto the outcoming char. More
>experiments will have to be conducted to find out how efficient and how fast
>the process can be.

(RWL-11): 1. This sounds like the venting operation. Do you have
a yield percentage yet?
2. I think the main reason this works is that there will be little
air flow through a horizontal pipe - there can be little draft. There will
be even less air flow the better you can plug one end. I like the idea of
sprinkling water on the output.

Priyadarshini-12:
> To answer the query about cleanliness results: We have not really
>given much thought to the pollution resulting from cookstoves apart from
>trying to reduce the visible soot and smoke emission. One reason for this is
>that we do not have any gas sensors/analysers to conduct that type of
>research. So far, the most sophisticated instrument that we have is the Bomb
>calorimeter!

(RWL-12): 1. I doubt that 10% of us on this list regularly use a
bomb calorimeter - I don't at all. This is not a high tech list, in
general. There is too little government support for stove research to
justify that sort of work (which is badly needed).
2. A few of us (not me) are using CO monitors and a few more have
systems to measure also percentages of CO2, O2, and total hydrocarbons.
This would be a great time for anyone knowing how to do these tests really
cheaply to let us know if something new has developed.
3. The reason for emphasis on CO is that there has been some
disagreement on this list whether wood or charcoal stoves are more apt to
be the higher emitter of CO - which is reported as a major health hazard.
Kirk Smith is currently developing this data on numerous types of stoves.

Priyadarshini-13:
> And finally a few lines about my work on artificial synthesis of
>diamond: The process has been known since 1950's and yes I have been
>successful in making diamonds. The basic concept is that if one has carbon
>atoms derived from any ordinary source of carbon and one creates local
>conditions such that the atoms are forced to form the metastable diamond
>structure rather than the stable graphite, then one would end up with an
>artificial process of making diamond crystals. The process I use involves
>thermal decomposition of hydrogen and methane (which is the carbon source)
>under vacuum. The hydrogen environment provids the diamond-favourable
>conditions. The diamond thus formed is in the form of a polycrystalline
>coating with each crystal of the size of a few microns. So it is useless as a
>piece of jewelry, but has a lot of applications in industry, especially as a
>cutting tool.
>
> Priyadarshini Karve.

(RWL): Thanks for this added information. I'd like to read your thesis.
I will pass up asking questions - but when you have figured out how
cook-stove users can participate in making diamonds (or C60 Bucky balls),
we assume you will let us all know.

Regards Ron

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