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chimneys, and wood firing vs. gas

updated thu 9 apr 98


Orion/Baker on tue 7 apr 98

I saw Marcia's piece today saying that she needed to raise the height of a
wood burning kiln's chimney in order to get it to draw at 6,000 ft. I
didn't doubt her for a minute when she said that flames shot out the top --
I'm sure that by speeding up the airflow, the entire combustion area got
quite a hustle -- the entire flame got stretched forward (upstream), and I
bet they really had to step up stoking speed to keep that dragon burning!
(I love a good fire, and I bet it was a hoot!)

But "thin air" is "thin air," and even fast moving or compressed thin air
is still "thin" in terms of ratio of nitrogen:oxygen, etc. The higher you
go in the mountains, the harder it is to keep any flame burning efficiently
-- gas or wood. Beyond some altitudes, there may be no way that anyone can
get their kiln up to full temperature -- no matter how hard they blow on
the coals!

What I was trying to share in the pieces I wrote about orifice sizing and
gas through-put (draught), was an approach to making gas firing at altitude
as efficient and controllable as possible, keeping as much heat in the kiln
chamber as long as you can (the place where it will do the most good).

I wonder how high (altitude) anyone's regularly done wood firing -- and
how/if they could get to Cone 10, Cone 6, whatever...

Best to all,

Ellen Baker - Glacier, WA

Vince Pitelka on wed 8 apr 98

>I wonder how high (altitude) anyone's regularly done wood firing -- and
>how/if they could get to Cone 10, Cone 6, whatever...

Ellen -
Someone ought to give Doug Casebeer a call at Anderson Ranch. They are at
very high elevation, and he is a long-time wood-firer. He seems to have it
figured out, because the Casebeer-designed kilns at high elevation seem to
fire better than the one he designed here at the Craft Center, at about 1000
feet elevation.
- Vince

Vince Pitelka -
Home 615/597-5376, work 615/597-6801, fax 615/597-6803
Appalachian Center for Crafts
Tennessee Technological University
1560 Craft Center Drive, Smithville TN 37166