Wilson Biochar Associates is working on a number of Flame Carbonizer Designs. We focus mostly on the Flame Cap Kilns. Below are pictures and descriptions of current and future kiln designs.
THE TURTLE KILN
This Flame Cap Kiln was designed and constructed by the North Dakota Forest service to process dead shelterbelt wood on farms. The biochar will be used to help establish new shelterbelt trees in the harsh conditions of the northern plains. This Turtle Kiln is made from an oil field tank cut in half and reinforced with a welded frame to make a half-cylinder trough. The dimensions of this kiln are 12 ft in diameter and 20 feet long for a total volume of 42 cubic yards. We started the initial run of the kiln without knowing how we would quench it. We had only about 1500 gallons of water available which would not have been enough to flood quench it. We considered dumping dirt on top to snuff quench, but we had two concerns: first, we did not want to dig up and disturb soil in the farmer’s field; and second, we worried that by adding enough dirt to smother the char, we might make the tank too heavy to dump. Luckily, we hit on a third alternative which was successful: we used the payloader to tip the tank completely over, “turtling” it so that the tank completely covered the char. We used the water to quench the small amount of char that fell out of the tank, and used the payloader to scoop a small berm of dirt around the edges of the tank to keep air out.
THE OREGON KILN
This Flame Cap Kiln is designed to process small diameter fuel load removal material and brush. This is material that would normally be burned in small hand-constructed piles in the forest. These kilns are also suitable for homeowners who are doing brush removal or cleaning up fallen trees and branches. The ideal feedstock size is six inches or less in diameter and four to five feet long. We have manufactured more than 30 of these kilns to date.
Here are open source plans you can take to a metal shop if you want to have one or more kilns made:
OREGON KILN PHOTOS
The Oregon Kiln weighs about 200 pounds and can be unloaded and moved by a hand crew.
Load the material in loosely and light on the top. There will be very little smoke with the flame on top.
The pile will burn down until it collapses into a pile of glowing coals.
Material up to 6 inches in diameter can be used.
Ideally, material will be 20% moisture or less. Up to 25% moisture is ok. This material was under cover and about 25% moisture. It worked fine, even in the rain.
Once the initial charge has burned down to coals, add more material, one layer at a time. The new material will prevent air from reaching the coals underneath so the char is preserved until you quench it.
Ready for quenching.
In the woods.
In a backyard in town.
LINK TO PHOTO ALBUM OF 199 PHOTOS OF OREGON KILN IN ACTION FROM 2015-2018:
BIOCHAR EXPERIMENTS WITH THE AIR BURNER
The air curtain burner has a blower to provide counterflow air. This is very useful with material that is wet and full of dirt. It can also process larger diameter material. In this picture the blower is off.
Scaling up allows us to use machinery for loading
The Air Burner produced very good biochar.
FUTURE DESIGNS - SCALING UP
We are working on several different approaches to scaling up. While the blower and refractory insulation used in the Air Burner are useful, they are not necessary. We will be testing different kinds of larger steel containers, earth pits and wind screen designs to cheaply and efficiently convert waste wood to biochar.
REFERENCES PERTAINING TO FLAME CARBONIZATION
Page-Dumroese, Deborah S., et al. "Methods to Reduce Forest Residue Volume after Timber Harvesting and Produce Black Carbon." Scientifica 2017 (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5362704/
Cornelissen, Gerard, et al. "Emissions and Char Quality of Flame-Curtain" Kon Tiki" Kilns for Farmer-Scale Charcoal/Biochar Production." PloS one 11.5 (2016): e0154617.
Inoue, Y., Mogi, K., & Yoshizawa, S. Properties of Cinders from Red Pine, Black Locust and Henon Bamboo. (2011). Presented at the APBC Kyoto 2011
Miller, C. A., & Lemieux, P. M. Emissions from the burning of vegetative debris in air curtain destructors. (2007). Journal of the Air \& Waste Management Association, 57(8), 959–967.