First Firing of the Oregon Kiln

Here's an album of pictures from the first firing of the Oregon Kiln that took place at Willow Witt Ranch on Nov 27, 2015. Thanks to Suzanne and Lanita of Willow Witt Ranch and helper Micah. Thanks also to Vicklund & Son for fabricating the kilns and mounting the jib crane to the trailer. The Oregon Kiln was designed by Kelpie Wilson, Wilson Biochar Associates (wilsonbiochar.com). The Oregon Kiln is a Flame Cap Biochar Kiln intended for use with forest slash and other kinds of waste wood commonly found in the forested regions of Oregon and elsewhere. 

Willow Witt Ranch Char Day Web Album

I was impressed with the efficiency of the kiln. We had some big chunks - 4"x4" and even a little bigger that charred nicely. And it did not take all day. I showed up at 10 am and we lit the rick at about 11 am. Quenched at around 5 pm. So the burn was only 6 hours long. Compare to my 4 foot diameter, 4 foot tall tube kiln that took 11 hours to fill. Total volume is almost the same. The Oregon kiln dimensions are 4' square bottom base, 5' square top base and about 25" elevation (sides are 26" wide).

Here is a simple description of how the kiln works:

You have to think of the Flame Cap Kiln as a retort that is made of steel on the bottom and of a stable gas vortex (actually a collection of vortices) on the top. Both function to exclude air, hold in heat, and char the feedstock.

Next task is to design some better wind screens - I'm thinking of something modular that can be moved around the kiln as needed.

These kilns are being used for a project to help farmers make their own biochar. Read more about that at www.ubetbiochar.blogspot.com

More pictures:

 

Making Biochar in the Snow

Making biochar in the snow. This Flame Cap Kiln is 14 ga (1.9mm) steel and it weighs less than 200 lbs. It's an inverted, truncated pyramid with a bottom base of 122 cm (4 ft), a top base of 152 cm (6 ft) and sides 66 cm (26") high. Capacity is 1.2 cubic meters. Cost $600 to make in Oregon, USA.

Edible Acres Does Backyard Biochar Right

Here is another very simple approach to backyard biochar from Edible Acres. Great job on this and you'll learn a lot of fine points about kiln operation from Sean's commentary. Pay attention to what he says about quenching!

Gary Gilmore's Bolt-Together Pyramid Kiln

Gary Gilmore is our latest contributor to backyardbiochar.net. Thanks Gary for your words and pictures, presented below, and thanks especially for the drawing that will help others fabricate their own versions of this kiln.

There are four pieces made from 1/8” (11 gauge) mild steel.  The top is three feet wide, each piece is two feet high and the bottom is one foot wide.  Each piece is identical and has a flange with bolt holes.  The battery powered drill  gives a sense of scale and facilitates screwing it together.

Pyramid Kiln
by Gary Gilmore

Last year I cut the end off an old tank that was four feet in diameter.  When laid flat the sides extended up about a foot.  A chain was attached to it for the tractor to drag it around to where the brush piles awaited to be made into charcoal.  The process is simple.  Start a fire in the big fire ring and keep adding brush.  As the wood burns, it turns to charcoal which falls to the bottom.  More wood is added over this to prevent oxygen from getting to the hot coals.  After several hours of adding brush, the fire ring is full of charcoal which is extinguished with water.  

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A somewhat similar arrangement is posted on the Green your head website run by Kelpie Wilson of Oregon.  It is called a Japanese cone kiln which is tapered.  This was a better design than the end of an old tank because the sides were sloped.  This helped radiate heat back up and funneled charcoal to the bottom more quickly so it would not burn up.

While thinking about the logistics of cutting and rolling a cone, Kelpie came up with four sided pyramid shaped kiln that gave good results.  The logistics of working flat steel suddenly became easier.  This design was welded together but got me thinking about a slight change to allow it to be bolted together.  With a pyramid kiln that can be bolted together you can easily ship it and disassemble it for storage.  

Here are some photos of my changes to the Wilson pyramid kiln.

The pyramid is assembled upside down.  It took three minutes to put this together.

The pyramid is now right side up and ready to use.  Note the flange on the top of each piece faces into the center of the kiln.  This gives the sides rigitiy and allow the sections to nest.

A closer look at the bolting flanges and the top flange.  There is a possibility this kiln can warp if it gets red hot.  If that were the case, it will be necessary to keep it bolted together.  Howerver, there is a chance this may not happen.  Time will tell.

Here the kiln has been unbolted and each piece nicely nests inside the other.  There are four panels in this picture.  This unit weights 75 pounds.

Open Source It! Layout for the 32" Pyramid Kiln

If you want to buy your own pyramid kiln, you can order one from Blue Sky Biochar on eBay. But these kilns are heavy and hard to ship, so they are only available by local pickup in Thousand Oaks, CA. You can also buy the 32" kiln from me, available by local pickup in Cave Junction, OR. I can also deliver to a few other locations in Southern Oregon and Northern California. Use the email link in the right hand column to inquire if you are interested.

You can also make your own. Just print out the layout sheet below (click on the picture for a bigger version) and take it in to a local welding shop and ask them to make you one. This layout actually makes 2 kilns, so make one for a friend, or use them both! We use 14 guage steel and 1/2" square tubing around the rim for stability. You can get fancy and add handles, a removable BBQ grill, a lid for dry quenching, etc.

Pyramid Kiln Layout. By Kelpie Wilson.

pyramid kiln layout 32 inch by Kelpie Wilson is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.
Based on a work at www. backyardbiochar.net.
Permissions beyond the scope of this license may be available at www. backyardbiochar.net.

Excellent Engineering Report on Moxham Kiln

If you are interested in designing biochar kilns, I highly recommend this report. You can download it here.

 

 

Biochar-Making Hot Tub

This is really neat. Carbon-negative hot tub. From Edible Acres.

 

Note on Terminology: Flame Cap Kiln is the Winner!

Earlier on this blog, I posted several ideas about terminology for the cone kiln pyrolysis method. I proposed the acronym TFOD - for Top-Fed Open Draft. While this is descriptive of the process of feeding and operating the kiln, it does not really explain the pyrolysis principle utilized. And it is JAUA - Just Another Ugly Acronym. 

So, after some discussion with friends at the Biochar Journal, we have converged on the terminology Flame Cap or Flame Curtain Kiln. I like Flame Cap Kiln because it best describes what I see in my kilns. The flame sits on top of the feedstock like a cap. The cap of flame excludes oxygen while applying heat.