Bed expansion and fluctuation in cylindrical gas solid fluidized beds with stirred promoters

Effect of vertical internals on the pressure drop in a gas‐solid fluidized bed

“…These physical properties are solid particle shape or solids sphericity (the glass beads have a spherical shape with a sphericity factor of 0.9 and the aluminum oxide has an angular or irregular shape with a sphericity factor of 0.74), the solids density (the density of glass beads is 2500 kg/m 3 and the density of the aluminum oxide is 3900 kg/m 3 ), and the particle size distribution (the glass beads have a particle size distribution of 300–340 µm and the aluminum oxide has a particle size distribution of 241–559 µm). These physical properties can affect the pressure drop and flow regime inside the bed, as well the gas‐solids flow patterns, solid circulation inside the bed, and the local and overall hydrodynamic properties of gas and solid phases, as indicated by many experimental works …”

“…The dimensionless groups are selected in this work based on the developed correlations available in the literature. The developers of these correlations have reported that these dimensionless groups have a significant effect on the pressure drop inside the gas‐solid fluidized beds for both with and without immersed surfaces …”

“…Table summarizes the studies related to the effect of different types and arrangements of internals, promoters, and baffles on the pressure drop inside different sizes and configurations of gas‐solid fluidized bed vessels. As listed in Table , several kinds of internals have been implemented, and these include vertical and horizontal rods with baffles, vertical wires and coils, different shapes of co‐axial promoters (rods, blades, and discs), vertical rods with different baffle configurations (circular, squared, and triangular), vertical twisted baffles, mechanically stirred promoters, and vertical internal rods …”

“…[6][7][8] Specifically, the formation of bubbles and slugs can increase the bed expansion, pressure drop, and fluctuations of the bed. [5] Various methods have been used to overcome the drawbacks of the gas-solid fluidized beds, and these include using a secondary fluidizing medium, [1] implementing mechanical stirrers [9] and baffled promoters, [6,10] operating in multistage units, [4] vibration of the bed and modification of the bed geometry, [4,8] using different types and configurations of internals, [5,11] and the use of corrugated walls in the bubbling fluidized bed. [12][13][14][15] Khan Wardag and Larachi and Khan Wardag et al have proven [12][13][14][15] that the implementation of corrugated walls inside the bubbling fluidized beds has several advantages such as improving gas distribution and heat transfer, promoting solids mixing and bubble size reduction, repelling the transition to bubbling, and smoothing out gas disengagement.…”

“…Table 1 summarizes the studies related to the effect of different types and arrangements of internals, promoters, and baffles on the pressure drop inside different sizes and configurations of gas-solid fluidized bed vessels. As listed in Table 1, several kinds of internals have been implemented, and these include vertical and horizontal rods with baffles, [6] vertical wires and coils, [11] different shapes of co-axial promoters (rods, blades, and discs), [3,7,20] vertical rods with different baffle configurations (circular, squared, and triangular), [10] vertical twisted baffles, [2] mechanically stirred promoters, [9] and vertical internal rods. [5,22] Among all of the kinds of internal surfaces mentioned above, many researchers have reported that the vertical internal tubes are considered the most important type of internals, especially [7] Co-axial promoters [20] Co-axial promoters Vertical discs 4.4 cm -Glass beads 1.7 mm 1.125 mm 0.725 mm 0.55 mm 2860 kg/m 3 2250 kg/m 3 1528 kg/m 3 Squared fluidized bed (0.83 x 0.83 m) 2008 Kaza [10] Vertical rods with circular, squared and triangular baffles Vertical rods 12 mm Copper Sand 930 mm 2520 kg/m 3 Squared fluidized bed (0.9 x 0.9 m) 2010 Padhi et al [2] Vertical baffles Vertical twisted tape Different sizes -Dolomite 0.605 mm -Fluidized bed column of 5.0 cm ID 2011…”