Friday, September 30, 2011

Preparing a Forced-air Wood Kiln

Here's a short video showing my wood kiln, which is almost ready to fire for the first time.  This is the first forced-air wood kiln I've ever seen.  Forced-air means that a fan is used to create the draft.  Normally a wood fired kiln does not use a fan, but instead relies on a tall chimney to create a suction or draft through the convection process of heat rising through the tall chimney.

The fire box is set slightly off-center (to the right) which was done to creat a swirling vortex.  This vortex extends the flame path through the firing space, providing more complete combustion and more even temperatures.

Initially this kiln was a gas-fired forced air kiln, built as a prototype under a grant I received from the New York State Energy Research & Development Authority (NYSERDA).  Originally it had 3 burners, each capable of producing 750,000 Btu per hour.  I built another conventional rectangular kiln of the same size, same wall thickness, same burners, etc., for the purpose of comparison.  My kiln proved to be 37% more efficient than the rectangular kiln, which is really quite an improvement.  This kiln is a downdraft, meaning that the hot flue gas vents at the bottom center of the kiln.

I adapted the original gas-fired design to a wood-fired configuration simply to see if it would work.   This is one big experiment: if it works well, it should fire faster than a conventional wood kiln.  A conventional wood firing usually takes around 3 days.  I'm hoping to cut that time substantially.  We'll see!

video

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