Pyrolysis of Wood in a Rotary Kiln Pyrolyzer: Modeling and Pilot Plant Trials

Abstract

Gasification is a key technology for the utilization of biomass as an energy carrier. The WoodRoll process developed by Cortus Energy is a multistage gasification process where drying, pyrolysis and gasification are conducted in separate units. A central role is thereby given to the pyrolysis step which provides the gas to heat the entire process. In the WoodRoll process pyrolysis is run in an indirectly heated rotary kiln. In this work we study pyrolysis in a rotary kiln by means of numerical simulations and by evaluating pilot plant data obtained from a 500 kW pilot. The simulations indicate the importance of the heat transfer to the solid bed and the exothermic pyrolysis reactions that occur in the late stage of the pyrolysis process. The latter can cause an overshoot of the solid bed temperature. Evaluation of the pilot plant data shows the robustness of the process, expressed in good reproducible and stable operation.