[Stoves] Understanding "charcoal making" stoves. Was: energy lost in charcoal makinag and briquetting

[Paul S. Anderson]

Dear Kevin and all,

Note:  I know this is a long message, but it is fundamental to understanding
T-LUDs and charcoal making stoves.  Your comfort is knowing that it 
took me far
longer to write it than for you to read it!!!  (3 AM, time for bed.)

I acknowledge the key similarities between these combustion devices, 
but I want
to establish clearly the key differences also.  Perhaps these devices are like
cousins in an extended family, but not like siblings (brothers and sisters)
that live in the same house.

First, some names (not official, but for clarity in this discussion):

Group A:  (siblings to each other, but cousins to Group B)
1.  Reed 1996 (The stove in the Reed-Larson 1996 publication)
2.  Reed WGCS (WoodGas CampStove)
3.  Anderson Juntos B (forced-air)
4.  Anderson Champion Stove (natural draft)
5.  Philips Stove (forced-air)
6.  Other Reed-based IDDs (includes experiments by Alex English, AJH, and
others)

Group B:  (siblings to each other, but cousins to Group A)
7.  Larson CM (Charcoal Maker) (shown to Dean Still and to A.D. Karve in late
1990s)
8.  Karve CM (Charcoal Maker)
9.  Burn-barrel Demo (to be described below)

I will use Kevin's words here (edited to fit the larger situation):
> As far as I can see from the descriptions..
> 1: Both [ALL 9 above] stoves are lit on the top
> 2: The draft is up in both [ALL 9] cases
> 3: They both [ALL 9] make charcoal
        (snip)
> Isn't that what a T-LUD is? Wouldn't the technology that you and AD employ
> be such that both stoves can properly be named "T-LUD Charcoal Making
> Stoves?"

That is true.  But this terminology is for the FAMILY and does not distinguish
between the COUSINS who are in Group A and in Group B.

In the past year I have tried to establish the name of T-LUD to mean some
specific technology found in a distinctive set of stoves that I have placed in
Group A above.  More specifically, I refer to them as T-LUD ___GASIFIERS___.

NOTE:  Please remember that my definition of a gasifier includes the 
ability IN
A CONTROLLED MANNER to create the combustible gases separately in both 
time and
space from the combustion of those gases, even if the separation is only
millimeters and milliseconds.  "Control" includes the ability to direct those
gases in different paths (prior to combustion!!) and to reasonably be able to
extinguish and re-ignite those gases.

Enter now the cousins in Group B.
1.  Group A and Group B do share a common ancestor, who is named Tom Reed, the
undisputed originator of a controlled top-lit updraft combustion device in
1985.

2.  Tom had contact and collaboration with Ron Larson in the mid-1990s to the
extent that Ron was the second author of the Reed-Larson 1996 paper.  But from
my discussions with both Tom and Ron, Ron's focus was consistently on the
issues of possible ceramic construction and of CHARCOAL MAKING.  I know from
Ron that he later went to Sweden and to Ethiopia showing a unique stove to
them.  I had always assumed that it was identical to the Reed 1996 device (#1
in the listing above).  Now I think that was not the case.  We have recently
learned from Dean and from A.D. that Ron showed them essentially a fuel can
that was ignited at the top and had air coming up from the bottom.  But what
was missing was (and still is) the upper canister that served as the combustor
of the gases.

3.  The lack of the combustor portion is a shared characteristic of the Larson
CM and the Karve CM devices.  If I am incorrect, I need Dean or A.D. or Ron or
someone to clarify the situation and to post photos so that we can see what
combustor(s) is/are in place and how it works.

4.  There is a related combustion phenomenon that pre-dates Tom Reed's work by
decades or even centuries.  I call it here the "Burn-barrel Demo."  I 
saw it at
my home in the 1950s, and many of you might also have seen it 
somewhere.  And it
can be replicated easily.

4a.  A "burn-barrel" is where rural folk throw their trash and then 
burn it. Often it is quite smokey, and not nice to do this in the 
cities.  There are
holes in or near the bottom of the barrel and it is clearly drafting upwards,
qualifying as "updraft".  It can be ignited at the top, qualifying as
"top-lit".  If the barrel happens to be filled about half or 2/3rds with dry
materials (crumbled paper works well) sufficiently packed to prevent the fire
from dropping embers to the lower levels but still allowing a somewhat
restricted up-draft to occur, we have the conditions for a "top-lit updraft"
combustion device.

4b.  Generally, the burn barrel makes smoke and has some flame down in the
barrel and eventually sends flames towering above the upper rim of the 
barrel. But on a windless day or in a very sheltered area, occasionally 
(or by user
intervention) the smoke coming out is sufficiently hot and deprived of oxygen
(because the updraft is not overly strong).  That smoke can reach the upper
rim, find oxygen in the surrounding air, and (if ignited by a spark or match)
can combust just above that upper rim.  I am speaking of a rather lazy,
hovering, non-turbulent flame that is probably less in height than half the
diameter of the barrel.

4c.  The burn-barrel demo is awesome to watch.  Captivating.  You can 
look at an
angle through the flame and see either smoke down in the barrel or 
no-smoke (you
are actually viewing through the transparent gases and seeing the blackened or
sometimes glowing fuel).   It is possible to extinguish the upper flame (this
yields voluminous smoke) and then re-igniting the flame, but this takes care
and practice.

4d.  After the burn-barrel demo is over, there is a large amount of 
charcoal in
the barrel.  Yes, it is clearly a charcoal making device.

4e.  Therefore:  The Burn-barrel Demo is a member of the Family that is 
top-lit
updraft charcoal making, but it is in Group B, therefore a sibling of the
Larson CM and the Karve CM stoves.

About combustion control:
Group A devices have some significant identifiable physical means to 
promote and
control combustion (which is separate from the creation of the combustible
gases).  In the natural draft versions (Reed 1996, Anderson Champion, and
others), the feature is a “chimney-type” extension (before or after the pot)
AND an opening (gap or holes) for entry of the appropriate amounts of 
secondary
air.  In the forced-air versions (Reed WGCS and Anderson Juntos B), the 
physical
feature (double-walled canister) directs the secondary air to appropriate
openings for mixing with the combustible gases.

A.D. Karve wrote:
>> The present model [of the Karve CM stove] does not allow any control 
>> over the fire
>> intensity, but it is possible to do so with certain additions and
>> alterations to the stove.

With admiration for the Karve inventiveness and hoping for your success 
because
we all want to see additional ways to control the fires, I respectfully doubt
that you will find any additions or alterations that are not already in the
Group A of this family of devices.  You and others are more than welcome to
utilize anything from the Group A stoves, but a resultant stove should then be
correctly classified as being in Group A.

AD also wrote:
>> but the stove
>> is so designed, that one can also feed additional pieces of wood, while it
>> is in use.
The feeding of additional fuel is able to be done (with differing degrees of
difficulty) in all of the Group A and Group B devices.  There is no rule
against this, and this action can be quite justified.  In fact, this is 
what is
done when the Group A devices are used in the “fan-blaster 
trickle-fuel” manner,
as discussed a couple of months ago.   When new fuel is added onto the top of
existing charcoal and flaming pyrolysis, that new fuel is NOT consumed in the
same way as during the top-lit stage of the operations.  Such operation is
therefore outside of the scope of this discussion.

Paul’s conclusions:
When you read or hear a specific name, you should have a clear 
understanding of
what is (and what is not) being referenced.  We will discuss these stoves and
names further, but I hope that my message above has distinguished 
between Group
A and Group B in the Family “X.”  To appropriately name the family and the two
groups is the next challenge.   The family could be characterized as “top-lit
updraft charcoal making” stoves, but is that the “name”?  Note that the word
“gasifier” was not include.

In my opinion, Group B devices do NOT qualify as “gasifiers” because of the
combustion control issue.  So the name “T-LUD gasifiers” might be acceptable
for Group A.  In my opinion, the designation of T-LUD (or TLUD or tlud) is
already understood by informed readers to identify the Group A devices.

I would not like to see the acronym “T-LUD” applied to the Group B 
devices. Perhaps call them “charcoal makers” (even though charcoal can 
be made in other
stoves), or “Karve charcoal makers” or “Karve-Larson charcoal makers”.

The identification of a few similarities on some key issues does not mean that
Group A and Group B are sufficiently the same to be called by only one 
name. There are some important differences.   Suggestions and comments 
are most
welcome.

Paul
-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson


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