586 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
in the sensors’ area, and ,yh {^is the electrical potential
distribution.
After the voltage was applied, the charge Q on the sen-
sor electrode pair can be calculated by Gauss’s theorem
,yhx Q r
j j j 0 d{ f f^x,y =-8 ^h (2)
where
j x is the closed surface around the electrode j
Then according to the definition of capacitance value,
the capacitance value between electrode pairs as follow
,,yhdx C V x y 1
ij j j 0 8 d{^ x f f =-^h (3)
where V
ij is the voltage between electrodes i and j.
Figure 3 depicts reconstructed images of a bubbling
fluidized bed experiment at different gas velocities but the
same sensor plane height. The images reveal that as the gas
velocity increases, there is a noticeable increase in the size
of the bubbles along the length of the bed. This indicates
that the growth in bubble size with increasing gas veloc-
ity is a normal occurrence in bubbling fluidized beds.
Additionally, when observing the images horizontally at the
same gas velocity, it can be observed that the projected area
of the bubble initially increases until reaching a peak, and
then decreases until it disappears. This variation suggests
that the shape of the bubble is either spherical or elliptical.
The peak projected area of the bubble on the sensor plane
represents its cross-sectional area at the center. Based on the
findings from Figure 3, it can be concluded that most of the
bubbles exhibit a periodic pattern of change in the plane
at each position, but some images may not clearly exhibit
this phenomenon. This is likely due to the complex nature
of bubble behavior in fluidized beds, which involves vari-
ous influencing factors, possibly including bubble coales-
cence during their ascent. Therefore, electrical capacitance
tomography provides a novel approach for tracking bubbles
in gas-solid bubbling fluidized beds[7].
Effect of Mesoscale Structure on Separation Density
The overall volume of the bubble phase in a gas-solid dry
heavy medium separation fluidized bed at the mesoscale
is closely linked to the macroscopic expansion of the bed.
This relationship has a direct impact on accurately predict-
ing the bed’s density. In the coal separation process, the
medium separation density needs to be adjusted between
1.3–2.1 g/cm3 due to the varying properties of the coal.
Analyzing the characteristics of the fluidized bed reveals
that it consists mainly of a bubbling phase and an emulsion
phase. The fluidization characteristics are also influenced
by the properties of the dense medium, which currently
falls into the Geldart B/D particle category. Typically, the
emulsion phase does not expand during the process of par-
ticle fluidization. To meet the requirements of different
Figure 3. Images of each sensor plane with time[7]
in the sensors’ area, and ,yh {^is the electrical potential
distribution.
After the voltage was applied, the charge Q on the sen-
sor electrode pair can be calculated by Gauss’s theorem
,yhx Q r
j j j 0 d{ f f^x,y =-8 ^h (2)
where
j x is the closed surface around the electrode j
Then according to the definition of capacitance value,
the capacitance value between electrode pairs as follow
,,yhdx C V x y 1
ij j j 0 8 d{^ x f f =-^h (3)
where V
ij is the voltage between electrodes i and j.
Figure 3 depicts reconstructed images of a bubbling
fluidized bed experiment at different gas velocities but the
same sensor plane height. The images reveal that as the gas
velocity increases, there is a noticeable increase in the size
of the bubbles along the length of the bed. This indicates
that the growth in bubble size with increasing gas veloc-
ity is a normal occurrence in bubbling fluidized beds.
Additionally, when observing the images horizontally at the
same gas velocity, it can be observed that the projected area
of the bubble initially increases until reaching a peak, and
then decreases until it disappears. This variation suggests
that the shape of the bubble is either spherical or elliptical.
The peak projected area of the bubble on the sensor plane
represents its cross-sectional area at the center. Based on the
findings from Figure 3, it can be concluded that most of the
bubbles exhibit a periodic pattern of change in the plane
at each position, but some images may not clearly exhibit
this phenomenon. This is likely due to the complex nature
of bubble behavior in fluidized beds, which involves vari-
ous influencing factors, possibly including bubble coales-
cence during their ascent. Therefore, electrical capacitance
tomography provides a novel approach for tracking bubbles
in gas-solid bubbling fluidized beds[7].
Effect of Mesoscale Structure on Separation Density
The overall volume of the bubble phase in a gas-solid dry
heavy medium separation fluidized bed at the mesoscale
is closely linked to the macroscopic expansion of the bed.
This relationship has a direct impact on accurately predict-
ing the bed’s density. In the coal separation process, the
medium separation density needs to be adjusted between
1.3–2.1 g/cm3 due to the varying properties of the coal.
Analyzing the characteristics of the fluidized bed reveals
that it consists mainly of a bubbling phase and an emulsion
phase. The fluidization characteristics are also influenced
by the properties of the dense medium, which currently
falls into the Geldart B/D particle category. Typically, the
emulsion phase does not expand during the process of par-
ticle fluidization. To meet the requirements of different
Figure 3. Images of each sensor plane with time[7]