Kilns and furnaces generally run on one of two methods. First is convection, second is forced air.
Convection relies on hot air rising, and needs a tall chimney to induce convection (venturi effect) to make it work.
Forced air relies on a powered fan to force exhaust gas out of the kiln or furnace, no tall chimney is required.
I am currently attempting to convert a former gas kiln to a forced air wood kiln. Wood kilns are never forced air, not in my experience. They always have a tall chimney, and take a long time to fire (around 3 days, stoking every 15 min. or so). Here's the kiln when it was operated with gas burners. It uses the triangular interlocking block system I've been describing on this blog.
The firebox is an inclined catenary arch. Inner arch is recycled kiln brick, outer arch is recycled red brick. I used refractory mortar inside and regular mortar outside.
I hope it fires faster than a regular venturi driven tall-chimneyed boring-ass kiln. Yes, I said boring ass. Ever fire a wood kiln? Pretty damned boring.
I plan to put the blower at the bottom, and a door for stoking wood on top. I'll do another entry on this kiln when it is completed and firing.