Impact of Gas Release on the Mixing of Large Particles in Bubbling Fluidized Beds
Publicerad
Författare
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
This study experimentally investigates solids mixing within a bubbling fluidized bed
using a fluid-dynamically downscaled cold model and Magnetic Particle Tracking
technology. The trajectories of gas-releasing tracers were tracked and compared
to blank tracers to analyze the impact of gas release on mixing for various tracer
densities and fluidization numbers. Lateral mixing was quantified using Einstein’s
equation for Brownian motion, and probability density functions was utilized to
analyze the axial position and velocity distribution of the tracers.
The results indicate that gas release significantly enhances the lateral mixing of low density tracers at high fluidization numbers, while it has a more pronounced effect
on the mixing of heavy tracers at low fluidization numbers. Additionally, gas release
affects the vertical distribution of tracers in a complex manner, depending on the
tracer density and fluidization number. Gas-releasing tracers with low density tend
to immerse more into the bed at low fluidization numbers, while high-density gas releasing tracers tend to remain at higher axial positions. The impact of gas release
on the velocity of the tracers is significant only at high gas release rates, for which
the force balance on the tracers seems to be impacted, causing higher fluctuations
in the velocity.
Beskrivning
Ämne/nyckelord
solids mixing, gas release, bubbling fluidized bed, biomass pyrolysis, magnetic particle tracking