[TheForge] Re: reducing fuel costs by improving forge efficiency.

[Jerry Frost]

I've sure let this thread get ahead of me. I don't know what it is about the
guys who sign my paycheck, they seem to feel I should show up on occasion.
<grin>

Anyway, from reading through this and the related threads most of what I had
to say has been covered. I'll touch on a couple directed to me:

I'm not sure how I'll deal with expansion and contraction in a large flat
hard refractory lid. One thought is to let it "float" on wide SS angle lips.
I'm sure a domed or vaulted lid would be better able to handle expansion but
I still want the freedom of sidewall placement a flat lid allows. I don't
know if I'll get what I want but what the hey. <grin>

If I can't make the rammable refractory work, I'll use a couple inches of
Kaowool and itc-100. If I have to go with Kaowool I'll try and get 2" but
that'll depend on whether the local suppliers has any drops, they sell 1" by
the foot but 2"+ by the roll. Attaching a single layer of 2" will be much
easier than multiple layers of 1".

I don't advocate any particular size or shape forge beyond this. Make it fit
what you do with enough leeway to do new things. How many bladesmiths get
along just fine with a bean can or hollow brick forge? On the other hand the
local spring shop . . .

Most of what little I've been doing the past few years has fit my oh so
small 6" x 12" pipe forge but as you can imagine it won't take even a hay
hook. Till I get the new forge built I use a combination of brick and
Kaowool to make large and odd shaped forges.

I'm going to direct my burners towards the center to help control dragon's
breath.

There shouldn't be a problem picking up exhaust gasses with the burner
intakes:

First, my intakes will be inside the heat shield which will be 36" long x
24" high and 2" deep. It's bottom 36" edge will be open to intake air for
the burners. This will provide a large volume of relatively low velocity air
in the heat shield. I'll also place a couple gates close to the burner
intakes on the back (cool) side of the heat shield just in case the
preheated air is too hot and caused preignition. I doubt this will be a
problem but it's easy enough to cover the contingency.

Second and more importantly, picking up some exhaust gasses in the burners
can easily be adjusted for.

A couple years ago,  searching the patent engines, I ran across drawings for
a "recuperative wall" furnace. This furnace had a gap between the inner
refractory fire chamber an the second insulating refractory wall and another
gap between it and the insulated shell. The burners drew their air from the
outer air gap which had it's intake ports on top of the furnace. The burner
nozzles stopped inside the middle refractory wall and shot through the first
gap and inner refractory wall to the fire chamber.

The burner flame entrained exhaust gasses from the first gap and sent them
back into the fire chamber to finish burning. This both consumed all the
fuel and all the oxy. The first gap gets very hot as exhaust gasses get
sucked into it and blown back out creating a layer of flame "insulation"
around the inner refractory wall. This made the inner wall and fire chamber
much hotter and isolated it further fom the ambient atmosphere.

The third gap in the wall preheated the intake air for the burners and stood
as a third layer of insulation. The outer gap wasn't particularly isolated
from the inner gap and exhaust gasses, the burners were simply tuned for a
clean burn.

Okay, a recuperative wall is WAY more complicated than we want to mess with.
(not that I haven't toyed with the idea. <grin>) I bring it up now just to
illustrate how aspirating exhaust gasses into the burners is not only not a
problem, properly done it can be beneficial.

As a departure point I'm going to set up the double walled heat shield for a
heat exchanger. I'll need a heat shield for the jack, gages, hoses, etc. so
it's a natural extension to turn it into a heat exchanger as well. However,
I don't know if it'll intercept enough heat to make a difference to the
burners. I suspect it won't. To increase the heat exchange I've considered a
couple options:

A second double walled Heat exchanger lid (H-lid) above and overhanging the
refractory lid (R-lid). This one would have openings on top, a few inches in
from the outer edge which can be opened and closed to direct intake air over
the hottest sections. It would be ducted either to the heat shield/exchanger
or perhaps directly to the burners.

The natural progression of this would lead to a double walled exhaust hood.
The hood would not only serve as a heat exchanger but it would duct the CO,
water vapor and other bad gas out of the shop. Of course it's always
possible none of them are worth the effort. Except maybe getting rid of the
bad gas of course. <grin>

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

Meadow Lakes, AK.