[Stoves] Baffle stove for serial TLUD operation Re: Dushanbe Stove

Sat Dec 5 10:36:04 CST 2015

Dear Paul

The idea was tried on a stove called Royal Ocean which is made in
Ulaanbaatar. Briefly the history of the company is that a Mongolian guy went
to Japan and learned how to make TLUD coal stoves there. When he got back to
Ulaanbaatar he reproduced their two cylinder, one chimney stove. He also
used the same name. 

It was brought for testing sometime in early 2011, in the final, or more
final version. As constructed it was two separate ignitions but we
(Lodoysamba and the guy and I) discussed at that time how to make one light
the other when it burned to the bottom. It was to use paper where you have
proposed gas. At that time, the TLUD approach was not fully accepted. The
reason for this was the intermittent nature (which was bound to lead to
problems) and the inevitable refuelling that would happen with a hot stove
(which did and does).

As to the merit of having it automatically ignite, I want to point to
something. This does not address your idea of a continuous operation with
dead cells being swapped when they are not in use, that is still possible. I
am referring the division of the available fuel space into separate zones.

Why do it? What does it offer that is an advantage over a single charge that
is either a side draft or a TLUD? One should answer that and be convincing
before complicating the process.  What the Royal Ocean stove did was to
provide two separate TLUD chambers with a damper system that allowed the
chimney to be connected to one or the other. It was a space heating and
cooking stove.

Having one light the other when it burned down allows the two to work in
series, no doubt about that. It saves the operator removing a cassette and
replacing it with a new one so it can burn longer. It was a good idea from
that point of view. It was a bit complicated in that it had to have two sets
of controls to get a good burn from two separate combustion ports. 

If I have a 'given size' of fuel loading space, I can't see a good reason to
divide it into smaller sections. One reason could be dropping the power to a
low level for a longer time, right? Can that not be achieved without the
complication? That is what I am wondering.

In the end the Royal Ocean product had a single chamber. I suspect the power
level was inadequate for the physical size, and the cost would have been
substantially higher to make and manage two separate stoves inside a single
housing. It was impressive to look at and nicely made, but all things
considered, a larger single chamber worked better.

A separate question: would the wall temperature of one chamber not
overheat/pyrolyse the fuel in the adjacent chamber? Royal had a gap to
prevent that, and they had the two separate with no gas connection between
them because that would have changed the control over the air flow (over and
under air).

I looked around for a photo and only came up with this which is the single
chamber version.

I cannot prove anything about why he changed his approach from two chambers
in series into one. Likely reasons are heating power and complexity.

Regards

Crispin

Frank and all,

Separate from the coal topic of Dushambe, so I changed the Subject line.   

About a Baffle stove:  On 12/4/2015 12:42 PM, Frank Shields wrote: [with my
additions in  [... ] brackets]

One idea [to attain a longer burn time] might be to add a night time insert.
That would [from the side] look like a IIIIIIII

with baffles that go almost to the base. The base has fuel [coal is being
discussed, but could be other fuel types] spread across the bottom.  You
lite [at the bottom] the one close to the door and that burns up quickly but
it takes longer to ignite the second baffle and even longer for the third
and so on..

Frank, I like the idea of baffles of some type.   Probably done in some ways
somewhere maybe long ago, but baffles are certainly not evident in currently
discussed stoves and therefore your idea is a new innovation for us 21st
Century stovers.

I want to add a further variation for consideration.   It is based on TLUD
principles.

Consider a rectangular fuel chamber with several vertical baffles running
across between the long side walls  (3 or 4 are sufficient for the concept,
but could be more.)   First thought was to have square vertical boxes that
are in a row, basically with one side shared by two squares.  (cylinders
with obvious spaces is a variation to discuss later).   Call them B1, B2,
etc for Box 1, Box 2......

Ignite B1 at the top and let the MPF (Migratory Pyrolytic Front) do its job
downward through that fuel, with burning of the created gases at the
combustor level.   When the MPF reaches near the bottom, it encounters a
hole on one side.  That hole is attached to a vertical pipe that is able to
receive some (maybe 20%??) of the pyrolytic gases.  (the percentage could
increase if the side hole is actually a vertical slit / hole that receives
more gases as more of the slit is in the zone of the MPF.)

The gases in the vertical pipe (call it an "ignition pipe") reach the top
and are ignited by the existing flame in the combustor.   But those
combusting gases are able to move upward into the combustor area of the
adjoining box B2.   In that way flame is into the area of B2, and within a
few minutes of time B2 has become Top Lit and begins to operate as a TLUD.
The process continues with B1 essentially shutting down (very little draft)
and several ways of extinguishing the created charcoal by an operator or
even "automatically".  

B2 ends and transitions to B3 in the same way.   If the burn-time of each
Box is approximately one hour (easy to accomplish with height and with
reasonable fuel like pellets), 8 boxes would operate the heater through the
night.

Quite literally, the boxes could be in a snake form or in a "6-pack" or 12
pack or spiral arrangement and continue for 12 hours or even longer.   If
the boxes were of different cross-sectional areas (different diameters),
there could be different intensities of heat at different times.  That is,
the five boxes B4 through B8 could have smaller X-section areas and give
less heat in the hours from midnight to 5 AM, when B9 could have a larger
fire.   

BTW, that B9 fire could be under a pot with bath water to be heated and
ready at 6 AM when needed.

What is described above is a system for CONTINUAL TLUD operation, as in a
serial continual sequence.   

This system should work also for larger (such as barrel-size) TLUDs for
making biochar AND with heat generation through a long cold night inside a
greenhouse.   

Of course it can be improved.   And it can have electronic monitoring and
the use of fans and blowers that can make the TLUDs respond in many ways.
Such a system can have bells and whistles (figuratively and literally) such
as alarms if temperatures go beyond user-specified highs and lows, or
digital CO sensors with alarms about the ambient air inside a greenhouse.

Should it be cylinders instead of square boxes?   One advantage of the
cylinders is that the vertical ignition pipe can be placed in the natural
area where the edges of cylinders are not touching 00000.   But shared walls
cost less in materials, and the heat through the walls help pre-warm (and
pre-dry) the fuel in the next box to be ignited.   But too much heat could
cause premature ignition.  These are considerations for experimentation.   

So, as of 9:30 AM CST on Saturday 5 December 2015, with the presentation of
this message to the publicly accessed Stoves and Biochar listservs, the
above ideas are made public.   I believe that I and Frank have some
intellectual property (IP) rights for one year after public disclosure.   So
if you want to try for patents, etc, you should include Frank and me.   But
instead, if your work is in the public domain, please feel free to get
started.   We want you to be successful.   But we do want to be kept
informed of activities and to encourage collaborative efforts.   

To move this concept / idea forward, we need some time and funding.   We
hope that it is YOUR time and YOUR funds, or that you help us find outside
funds that can pay for the time and materials.   Frank and I are both
retired.   And we do not have the metalwork shops that should be involved
with this work.   So we encourage your participation, and please keep us
informed of your initial interest (which means tell us SOON), your initial
activities, progress, results, and plans for taking it further.   Our email
addresses are:    Paul Anderson  <mailto:psanders at ilstu.edu>
<psanders at ilstu.edu>   and   Frank Shields  <mailto:franke at cruzio.com>
<franke at cruzio.com>

We look forward to the discussion and to any activities.   This might all
blow over and become nothing.   Or it might be a major step forward.   

Paul

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