Process Design and Operation of a Wood Charcoal Retort

Abstract

An efficient approach for the development of a compact integrated wood charcoal retort was designed. The key fundamental requirements to guarantee efficiency and productivity are initially investigated via CFD simulations to identify the temperature and velocity profiles inside the unit. The final compact design is comprised of a double vessel arrangement where the wood to be carbonized is placed in the central vessel (i.e. carbonizer). A flue-gas recycle line leaves the outer vessel (i.e. combustion furnace) to preheat the wood in the carbonizer during startup. This design allows the syngas/methane leaving the carbonizer to be re-circulated into the combustion furnace to provide the necessary energy. The integrated compact retort system is further tested experimentally; only 2–3 h were needed to achieve complete carbonization of oak wood. Various temperatures are achieved during operation, the maximum of which is at 900 °C. The charcoal yield ranged between 37 and 46% on a dry basis, and the charcoal carbon contents were between 73 and 87%.