[Stoves] Fan-blaster Combustors, Stove Camp 2006, and the Dell-Point Pellet Stove

[psanders at ilstu.edu]

Dear Tom and Stovers,

[[[   I hope all who are following this exchange of messages will look at the
full posting at the  Bioenergylist.org   website.]]]

I agree that the terms that you describe are standard, but none of them
specifically "labels" or "identifies" that I have called a "fan-blaster."  A
label or identifier is not required to "describe", but is required to
eventually (if accepted into use) bring to mind something or some set 
of things
that is distinctive from other things (or methods/processes/etc).

I started by saying: --  "Essentially a controlled stream of focused air is
directed onto a small amount of fuel that is being continually 
replenished."  A more complete description is given later in the 
posting.

And I gave examples: pellet stoves, and in the way that 3 stoves were 
used when
tested at Stove Camp.  The issue of naming or labeling is merely to keep the
focus on that very specific style and method of combustion.

The real issue is not the "name" itself.  The issue is the recognition 
that this
type of combustion is distinctive.  Indeed, it is sufficiently distinctive to
have merited selection for the Cat Pee award.

Is a name necessary?  I contend that a name is needed to have all people
discussing the same very specific type of combustion.

You and others are invited to suggest names.  You have not yet suggested an
alternative name.

I disagree with you on two issues:

1.     Tom Miles wrote:     > But it
> does make a catchy tag that you might use to describe the behaviour in your
> Juntos fan stove.

In my posting that is complete at the   Bioenergylist.org    website, I
specifically stated that the Juntos B stove was NOT even tested as a
"fan-blaster".  Juntos B is a true T-LUD, as is Reed's Woodgas Campstove,
because they can be operated correctly with T-LUD combustion.  Only when
someone uses either one with the fan-blaster style of combustion should the
fan-blaster name be mentioned.

2.  Tom Miles wrote:
> (You claim that the woodgas stove in the Stove Camp test was not
> operated in a normal manner. Perhaps the people who tested it can explain
> how and why.)

I know how it was tested because Dale Andreatta and I were the testers and we
used the precise methods that were shown to us by Damon Ogle and Dean 
Still. And we were able to watch Damon operate the Phillips stove that 
way, and Dean
to operate that way his creation (called "Dean's fan" on the graph) that used
the fuel combustion cup taken from the Woodflame Gusto.

And it was Dean who clearly stated to me that the Woodgas Campstove has been
repeatedly operated in this same way (what I am calling "fan-blaster") in
previous emissions testing because the duration of the burning by a 
single load
of fuel in the small fuel chamber of the Woodgas Campstove was not sufficient
for completion of the WBT Water Boiling Test.  I am sure that is true because
the Campstove's capacity for the "official wood" used in all emissions testing
at Aprovecho is significantly less that what is needed to accomplish even the
boiling of 5 liters of water, and then still to have the pot simmer for 45
minutes.  I understand and accept that way of operation during those tests
because the Woodgas Campstove is not able to be reloaded for further T-LUD
operation without removing the pot, emptying out the char/ash, partially
cooling the inside of the stove to prevent ignition at the bottom, and then
reloading and relighting for T-LUD operation, and replacement of the pot onto
the stove.  Such a procedure is not convenient, so the procedural solution was
use what I am now calling "fan-blaster" combustion.  What is interesting is
that the "fan-blaster" mode of operation was not recognized or noted or
reported, and we thought it was a T-LUD operation.

Some stoves can only be operated in the fan-blaster mode:  Woodflame 
Gusto, and
pellet stoves (the type for residential usage).

Some stoves can only be used in the T-LUD mode:  Champion stove, Midge stove,
and some others that only use natural draft.  No fan = no fan-blaster
operation.

Some stoves can be used in either the fan-blaster mode or the T-LUD 
mode: Woogas Campstove, Phillips stove, Juntos B stove.

My conclusion to the complete item posted at the website was quite favorable
about the prospects of fan-blaster combustion.  It is worthy of 
recognition and
possible development.  Therefore, it deserves a name so that we can identify
what we are talking about.

Paul

Quoting Tom Miles <tmiles at trmiles.com>:

> Paul,
>
> The term "fan-blast" does not adequately describe the operation of these
> forced draft, or fan, stoves. There are conventional terms for what you are
> describing so there is no need to invent new terms. A combustor is either
> natural draft or "forced draft". When a fan is used to supply air under
> pressure to the fuel it is called a forced draft fan. There are many
> variations of forced draft burners.
>
> "Combustion air" is air used for all stages of combustion whether it is used
> to promote gasification or combustion. Gasification air is sometimes called
> primary air. Air supplied to burn off the volatiles is often called
> secondary air. If primary air is delivered to a furnace/burner through
> openings in furnace walls(s) below the main fuel it is called underfire air.
> Secondary air, which is usually supplied in the zone of gaseous combustion,
> is sometimes called overfire air.
>
> Air is supplied through openings, nozzles or tuyeres. The arrangement of the
> air supply depends on how the designer wants to control the fire. While
> Dell-point appears to have gotten a (1998) patent on a spiral pattern for a
> cup-type pellet stove there is really nothing unique about this. I have been
> working with burners with this kind of tuyere arrangement for more than 30
> years. We use the tuyere geometry and the air pressure to control the
> combustion. You'll find this kind of arrangement in Crispin's discussions as
> well. Tom Reed is correct in concluding that the arrangement of air holes in
> the burner is intended to stage the combustion, partly to reduce slagging.
> There is a well known industrial version of this kind of burner that
> performs in the same way.
>
> Air impingement on the fuel is not unique or characteristic of the group of
> burners you call top fed. Air impingement is a common combustion technique
> to remove the boundary layer of gases at the surface of the wood, like
> blowing on a fire. The blowtorch effect can also be created using an induced
> draft stack or fan in which the energy for pulling the air onto the fuel is
> from a stack or fan that exhausts the hot gases from the furnace. This was a
> basic part of Richard Hill's stickwood furnace design. I don't think the
> blowtorch effect is necessarily common to all the burners you describe. You
> have not shown us the specific locations of air and fuel and the volumes of
> airfow to the fuel in each case. If you look closely at the designs of all
> four stoves you will find significant differences in their design and
> operation. I think the tuyeres in Tom Reed's woodgas stove or the Phillips
> stove are intended to burn gases above the fuel not solids at the fuel
> surface. (You claim that the woodgas stove in the Stove Camp test was not
> operated in a normal manner. Perhaps the people who tested it can explain
> how and why.)
>
> I am not ready to accept a "fan-blaster" classification for forced or induce
> draft burners that employ air impingement as a combustion technique. But it
> does make a catchy tag that you might use to describe the behaviour in your
> Juntos fan stove.
>
> Regards,
>
> Tom Miles
>

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