Armstrong, Lindsay-Marie, Gu, Sai and Luo, Kai H.
Three-dimensional modelling on the hydrodynamics of a
circulating fluidised bed.
In, Proceedings of the Inaugural US-EU-China Thermophysics Conference, UECTC-RE ’09, Beijing, China,
28 - 30 May 2009.
American Society Of Mechanical Engineers Press12pp.
The rapid depletion of oil and the environmental
impact of combustion has motivated the search for clean
combustion technologies. Fluidised bed combustion (FBC)
technology works by suspending a fuel over a fast air inlet
whilst sustaining the required temperatures. Using biomass
or a mixture of coal/biomass as the fuel, FBC provides a
low-carbon combustion technology whilst operating at low
temperatures. Understanding the hydrodynamic processes in
fluidised beds is essential as the flow behaviours causing heat
distributions and mixing determine the combustion processes.
The inlet velocities and different particle sizes influence the
flow behaviour significantly, particularly on the transition
from bubbling to fast fluidising regimes. Computational
modelling has shown great advancement in its predictive capability
and reliability over recent years. Whilst 3D modelling
is preferred over 2D modelling, the majority of studies use
2D models for multiphase models due to computational cost
consideration. In this paper, two-fluid modelling (TFM) is
used to model a 3D circulating fluidised bed (CFB) initially
focussing on fluid catalytic cracker (FCC) particles. The
transition from bubbling to fast fluidisation over a range
of velocities is explored, whilst the effects on the bubble
diameter, particle distributions and bed expansion for different
particle properties including particle sizes are compared. Drag
models are also compared to study the effects of particle
clustering at the meso-scale.
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