[Clayart] Jeff's kiln ?
23drb50 at gmail.com
Thu Dec 17 21:05:30 EST 2015
Most of our kiln design lore* is based on 19th century research passed on
by Matsubaiyashi to Leach, Cardew, Olsen.
What can we pick from them?
Yes, a flue exiting below the shelves and burner entries is good.
Chimney draft provides air for combustion. So they are in proportion to
BTUH's required. In a fiber kiln the chimney can be smaller but in height,
diameter or both? The fuel needed per cu. ft. of kiln given by Olsen for
DFB and IFB suggests a soft brick kiln needs a chimney 60% the size of a
soft brick kiln. What does fiber need 40%? 33%?
Short fat chimneys with a small entry from the kiln go way back in China so
I'd go there. A fat one, slightly taller than the kiln.
To me this is more like getting a sense of the dance rhythm of the flame
through the kiln; rush through the fire-mouths, slowly through the wares
giving up heat, quickly under the ware stack (less heat transfer at the
base where the pressure of the load adds stress to the structure), a little
slower through the trench to squeeze out a bit more heat to the kiln,
another quick passage through the side of the base of the kiln (again less
time in passage = less heat stress to structure). All of these tempo
changes are from changes in the Creek
of cross section. Small = fast, large = slow.
So if your nominal chimney is 8"® maybe the areas of the various parts are;
fire mouth total 50%, area of exit under shelves 50%, area of trough 75%,
exit to chimney 50% and chimney 120% of design chimney.
*Nils' and Mel's books haven't been around long enough to become
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