This consists of heating the ground wood, after it has been introduced into a reaction column, by subjecting it to a current of hot gases. This causes an adiabatic combustion, which leads to the volatile elements being gasified, whereas the mineral elements remain entrapped in a coal-type residue which is very rich in carbon (6500 kcal/kg). The temperature of the heating gases is substantially below that generally used for thermolysis. This process requires a precise control of the temperature, the pressure, the O2 and the CO content of the heating gases. These are the basic factors of the process which we call "chartherisation".
Two other characteristic factors which are an integral part of
"chartherisation" are : 
rapid cooling. This has
the purpose of causing condensation which entraps all the condensable elements which the
gas leaving the adiabatic combustion process may contain.
recirculation of the gases
from adiabatic combustion. They are loaded with hydrocarbons and are recovered and used as
fuel for the hot gas generator. The combined effect of the low temperature levels required
and the high hydrocarbon level in the gases coming from the reaction column makes it
possible to keep the system in a state of auto-combustion.
All the recycled gases are burnt at more than
850C for more than 2 seconds as required by the regulations in force, before being reused
or discharged.
Whereas the level of ground wood is readjusted
continuously at the head of the reaction column, the charcoal residue is extracted from
the bottom of the column at the rate at which it is produced. It is then cooled,
compressed, removed and stored ready for use to feed the subsequent stage.
| 1. Hopper 2. Wood shreds input 3. Gas output 4. Reactor 5. Wood shreds at different levels of chartherisation |
6. Grate 7. Hot gas input 8. Charcoal extraction 9. Charcoal output |
