Although they are not pyrolisis stoves and do not produce biochar, I have included this section on rocket stoves because I have used some of the design principles of rocket stoves in making the Biochar Rocket Stoves.
Rocket stoves, designed by Larry Winskiari, consist of an elbow of pipe or equivalent which is surrounded by insulation.
They have proved very effective and popular for two reasons;
1, they are very efficient and
2, it is easy to capture the heat they produce.
There are two features of a rocket stove which cause it to burn wood very efficiently;
1, the combustion chamber is surrounded by insulation which causes the fire to generate a strong draw of air,
2, the elbow of pipe used as the combustion chamber synchronises and directs the inflow of air into the fire.
It is easy to capture the heat produced by a rocket stove because the draw of air happens as a result of insulation which is part of the stove. (Wood stoves usually rely on a vertical flue pipe to cause enough air draught for an efficient cobustion.) It is therefore possible to direct the flue gases horizontally with rocket stoves. The heat in a horizontal pipe keeps rising upward, causing more of the heat to transfer through the pipe wall. Surrounding the pipe with a thermal mass such as a cob wall, bench or bed, captures heat and slowly releases it after the stove has gone out.