Design of a High Temperature Reactor Fed by a Plasma Torch for Tar Conversion: Comparison Between CFD Modelling and Experimental Results

This paper deals with the modelling and the commissioning of a high temperature reactor (Turboplasma (R)) devoted to the thermal cracking of tars held in the product gas leaving a RDF/biomass gasification unit. High temperatures are reached in the reactor thanks to a plasma torch that can reach up to 5,000 K. In a first section, information on the model that was derived to design the reactor is given. This model relies on the CFD Software Ansys Fluent. A specific reaction pathway and the associated kinetics were set up in the software to characterize the degradation of model tars (naphthalene, toluene and benzene). Specific physical properties were also used to characterize the properties of the plume of plasma downstream the torch. The overall model was used to check the efficiency of several reactor configurations and then to build the experimental reactor. This reactor was tested downstream a fluidized bed gasifier and information on the operation of the overall process is provided. In a second section, the results of the CFD computation as well as the results of the experimental campaign are provided. These last ones show that the efficiency of the real reactor is better than the computed ones. Comparison of both results reveals discrepancies, which led us to modify the reaction pathway model in order to take into account the gasification of char produced in the fluidized bed reactor and entering the Turboplasma (R).