Optimization of a Horizontal Entrained Flow Plasma Gasification Test Rig through CFD-Simulation

Plasma gasification is a promising method for the thermochemical conversion of biomass and wastes into high quality syngas with lower tar content and higher energy densities compared to conventional processes. This study aims to optimize a horizontal tubular entrained flow plasma gasification test rig which should produce plasma pyrolysis chars. Therefore, mixing of fuel particles in the plasma zone as indicated by the respective particle temperatures needs to be improved. For that a couple of configurations were investigated by a CFD simulation in Ansys Fluent: First, the plasma torch gas outlet diameter of 1mm was doubled to reduce plasma gas velocities. Then, several vertical fuel particle inlet tubes were integrated at different distances from the plasma torch nozzle (5, 15, 25 and 35mm) to insert fuel particles more directly into the plasma zone. The wider nozzle outlet diameter resulted in higher particle temperatures, lower velocities and better convergence. From the different particle tube configurations, the closest to the plasma inlet, resulted in the highest average particle temperatures, residence times and better distribution in the reactor than the other cases. It was subsequently concluded that the optimal configuration for enhanced particle heating and mixing shall be designed with a 2mm wide diameter and a 49mm long tube that is 5 mm away from the torch outlet.