Simulation of Particle Segregation in Fluidized Beds

Fluidization technology is widely used in solid processing industry due to the high efficiency, high heat and mass transfer rate and uniform operating conditions throughout the reactor. Biomass gasification is an emerging renewable energy technology where fluidized bed reactors are more popular compared to fixed bed reactor systems due to their scalability to deliver high throughput. Fluidization of large biomass particles is difficult, and the process is therefore assisted by a bed material with higher density. The combination of different types of particles makes it challenging to predict the fluid-dynamic behavior in the reactor. Computational particle fluid dynamics simulations using the commercial software Barracuda VR were performed to study the fluidization properties for a mixture of particles with different density and size. The density ratio for the two types of particles was six, which is the typical ratio for bed material to biomass in a gasifier. The results from simulations with Barracuda VR regarding bed pressure drop and the minimum fluidization velocity, show good agreement with available experimental data. The deviation between experimental data and simulations are less than 12%. Particle segregation was clearly observed both in the simulations and in the experimental study.