This set up is designed to obtain wood distillates with charcoal and heat as byproducts. Fine if you want the distillates, but I'd classify it as a slow method if all you want is charcoal.
The inverted drum filled with wood is place over a base and sealed with sand. A larger drum is lowered over it to insulate and keep the interior drum hot. In this base is a hole that contains fire. Its purpose is to heat the wood in the drum to the point where it can self pyrolosis. There is a door on this hole (located underneath) where more wood can be fed in should more heat be necessary to get the reaction started. The other hole covered by the wood filled drum leads through a pipe that is immersed in water. This is what the two blue drums filled with water are for. To condense the wood smoke. The condensed material is collected in a pot while the uncondensable component of the process is flared off and use to boil water.
The condensates are primarily three components. Precipitated tar (thick and black) wood vinegar/wood methanol, and water/oil. This mixture needs about 6 or more months standing in a vessel to get the wood vinegar/wood methanol to settle from the water/oil and more tars. This material is then used in various doses on plants. A 1part wood vinegar to 200 parts water helps make thicker leaves. A 1 ; 50 ratio can control nemetodes in the ground. The Thai's are starting to use this material more as are the Japanese. It is also a product I am interested in and have done some research and experimentation with,.
A quick definition. Wood Vinegar - "Wood vinegar, technically known as pyroligneous acid, is a condensed liquid of the smoke generated by charcoal production (Yoshimoto, 1994; Kishimoto, 1997). Wood vinegar contains 80-90% water and 10-20% organic compounds including more than 200 chemical components with mainly acetic acid. It also contains various kinds of phenol, carbonyl and alcohol compounds. Wood vinegar is widely used in agricultural crop production toward plant growth stimulation, germination, soil disinfection and the control of weed, disease and pest.
Gary in PA