[TheForge] photos under "inexpensive recuperative forge"

[Michael]

Jeff,
Yes there is such a design. We discussed it on this list last summer. What
you need for safety is to build the heat scavenging into the forge body
rather than into the burner. The only kind of burner that will safely use
preheated air is a nozzle mix type. By the time you have gone to that much
trouble in anything short of large industrial equipment, you're working too
hard (translate spending too much) on the problem.

There are three practical paths to building a heat recuperative craft forge.
They can work on various heating equipment devices, but would probably be
best suited to heating ceramic chip media:

(1)Design the body with double walls. Then, exploit the power of buoyancy by
placing the air entrance in the outer wall a good deal lower than the air
exit(into the fire-box) above the burner area, employing a fan-blown burner
that will produce a large secondary flame so that the super-heated air has
something to combust. The fan-blown burner is merely used to create a more
diffuse flame in order to avoid overheating the forge structure in the
combustion area; a poor naturally aspirated burner design, which produces a
large secondary flame will serve equally well. This design requires no added
power to move the superheated air itself and is therefore the safest; it is
also the least efficient.

(2) Employ a fan in the bottom of the forge's inner wall, in order to draw
super-heated air down to the bottom of the fire-box against the power of
buoyancy, and inject the fuel into the fire box (above the fan). The
shortcoming in this design is the fan placement, which would require it to
be made of refractory materials. And spun by an exterior power source; this
should be a fun problem for electrical types to mull over (of course, the
fan could be sealed and use to push air in, which brings us to solution
three, below).

(3) Inject compressed air into the top of the air space between the forge's
inner and outer walls , creating positive pressure to push the super-heated
air down to the bottom of the fire-box against the power of buoyancy, and
introduce the fuel in the fire box (above the fan) from an injector tube.
This also has some problems: The air must be regulated to keep pressure from
building past the ability of the refractory to withstand it; a compressor
must be running to provide the air.
Mikey

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jeffrey Polaski
Sent: Friday, July 21, 2006 3:55 PM
To: Sponsored by ABANA
Subject: RE: [TheForge] photos under "inexpensive recuperative forge"

>The potential problem with this kind of heat 
>exchanger/scavenger is overheating the air/fuel and 
>having it ignite in the burner tube. Controlling the 
>preheat by blocking the open pipe might work.
Isn't that true of any recuperative forge? At least, if it gets at all
hot I'd think there would be a problem. Is there a design where it's not
a potential problem?


Jeff Polaski
Research and Graduate Studies Webmaster
University of California, Irvine
http://www.rgs.uci.edu/
949.824.6363

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Jerry Frost
Sent: Friday, July 21, 2006 12:15 PM
To: Sponsored by ABANA
Subject: Re: [TheForge] photos under "inexpensive recuperative forge"

Bob.

What Jeff did was run his burner tube through a large 
"T" and pipe to the forge. Part of the exhaust is 
routed through the larger pipe surrounding his burner 
tube for the preheat. The open pipe sticking out of the 
"T" is the forge exhaust port, not the burner air 
intake.

It isn't heating the intake air, it's heating the 
air/fuel mix as it runs down the burner tube.

The air intake is on top and looks to be a basic linear 
induction burner. (Aussie, Reil, etc.)

The potential problem with this kind of heat 
exchanger/scavenger is overheating the air/fuel and 
having it ignite in the burner tube. Controlling the 
preheat by blocking the open pipe might work.

Let us know how it works Jeff.

Frosty
-------------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.

http://www.artmetalradio.com/

From: <schade at acegroup.cc>


> Jeff,
>
> Glad to see that the photoaccess site worked for you. 
> I took a look at your pictures. The way it looks to 
> me the 'recuperative' part of your forge is the fact 
> that you are drawing in hot combustion air from the 
> area above the door where the heat drifts/blows out? 
> Wouldn't this hot air have less oxygen than cooler 
> air? Wouldn't that actually be reducing the 
> efficiency of your burner?
>
> Maybe I am seeing this all wrong?
>
> Bob
> ______
>

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