Flame Cap Kilns come in many different shapes and sizes. They all seem to work quite well, but there are some fine points of design that will help users determine the most appropriate configuration. Parameters to consider include feedstock type, available materials and cost. Keep in mind that large round cone shapes can be more expensive to fabricate in small welding shops than pyramid or trench shapes. On the other hand small cone shapes may be easier in some cases. Tubes can often be found ready-made. Look for other ready-made containers like small dumpsters or old tanks. You also need to consider how you will quench and unload your char. More on that later.
This Flame Cap Kiln Design Guide is a work in progress, but I want to share it now because I am getting busy with other projects and I don't know when I'll be able to get back to this to make it more complete. You can download the Flame Cap Kiln design guide, or just take a look here:
Backyard Biochar This site has descriptions of my experiments with Flame Cap Kilns. I also report on work by others.
US Biochar Initiative I am on the advisory board of the USBI. We are sponsoring the 5th North American Biochar Symposium in Corvallis, Oregon - August 22-25, 2016
Illinois Valley Forest Collaborative I've been involved with the group in my hometown for several years. We are working with the US Forest Service on hazardous fuels and small diameter timber sales. Biochar is a part of what we do.
Umpqua Biochar Education Team (UBET) I am working with UBET on a Conservation Innovation Grant from the USDA-NRCS. We are helping small farmers learn how to make biochar and use it to manage manure and make premium compost.