7.5 Drop Size Distribution
7.5.1 Effect of gas and liquid flow rates on the drop size distribution
Influences of superficial liquid velocity with dispersed liquid of paraffin liquid-water at different gas velocities are shown in Figure 7.9. For the scale along the x-axis, the value “0.37” signifies the range of drop diameter (dd ≤ 0.37 mm), and the second region denotes the drops of 0.37 mm
≤ dd ≤ 0.74 mm. Figure 7.9a represents the number density curve of drop size in the presence of 5% paraffin liquid at different superficial liquid velocities and, at a constant gas velocity of 0.84×10-2 m/s. With an increase in the liquid velocity, it is observed that a broad drop size distribution results compared to that of lower liquid velocity (usg = 0.84×10-2 m/s − 2.54 ×10-2 m/s) in paraffin liquid system. This is due to the more momentum with an increase in superficial liquid velocity. The increase in the superficial liquid velocity from 4.24×10-2 m/s to 1.20×10-1 m/s, the drop size distribution region moved further to the larger drop diameter. The maximum number density of the drop size distribution curve shifted from 1.10 to 1.62 mm after an increase in the superficial liquid velocity of 7.64×10-2 m/s from 4.24×10-2 m/s. The drop size distribution curve shifted from 1.62 to 1.89 mm after an increase in the superficial liquid velocity of 1.05×10-
1 m/s and a furthermore increase in the superficial liquid velocity of 1.20×10-1 m/s, it shifted to 2.42 mm drop diameter. When the volume fraction of paraffin-liquid is increased by 15% and
25%, it showed the same trend as discussed above, which is shown in Figure 7.10(a) and 7.11(a).
0.5 1.0 1.5 2.0 2.5 3.0 3.5
0 20 40 60 80
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(a)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0 10 20 30 40 50 60 70 80
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(b)
Figure 7.9: Variations of drop size distribution with superficial liquid for 5% (v) of paraffin liquid at (a) usg = 0.84×10-2 m/s, (b) usg = 2.544×10-2 m/s
Figure 7.9b shows the number density curve of drop size by increasing the gas velocity from 0.84×10-2 m/s to 2.54×10-2 m/s. It is seen that the size distributions of drops with paraffin liquid- water system at higher superficial gas velocity is higher than that at the lower superficial gas velocity. With an increase in the gas velocity, the drop coalescence increases in the column. It is observed that with an increase in superficial liquid velocity, the drop size distribution region moved further to the larger drop diameter. The maximum number density of the drop size distribution curve shifted from 1.42 to 2.00 mm after an increase in the superficial liquid velocity of 7.64×10-2 m/s from 4.24×10-2 m/s. The drop size distribution curve shifted from to 2.29 mm after an increase in the superficial liquid velocity of 1.05×10-1 m/s. Further increase in the superficial liquid velocity of 1.20×10-1 m/s, it shifted to 3.45 mm drop diameter. When the volume fraction of paraffin-liquid is increased by 15% and 25%, it shows the same trend as
discussed above, which is shown in Figure 7.10(b) and 7.11(b).
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0 20 40 60 80
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(a)
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 0
10 20 30 40 50 60 70 80 90
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(b)
Figure 7.10: Variations of drop size distribution with superficial liquid velocity for 15% (v) paraffin liquid at (a) usg = 0.84×10-2 m/s, (b) usg = 2.544×10-2 m/s
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
0 20 40 60 80 100
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(a)
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 0
20 40 60 80 100
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(b)
Figure 7.11: Variations of drop size distribution with superficial liquid velocity for 25% (v) of paraffin liquid at (a) usg = 0.84×10-2 m/s, (b) usg = 2.544×10-2 m/s
Figure 7.12 represents the number density curve of the drop size of the kerosene-water system at
different superficial gas and superficial liquid velocities. Figure 7.12a represents the number density curve of drop size in the presence of 5% kerosene at varying superficial liquid velocity and, at a constant gas flow rate of 0.84×10-2 m/s. As in the case of paraffin liquid, the drop size distribution is observed to increase with the superficial liquid velocities. However, in the case of kerosene, the range of drop size is found to be lower than that of paraffin liquid. As the kerosene viscosity is less than the paraffin liquid, it disperses in the continuous phase and forms smaller drops compared to that in paraffin liquid. From Figure 7.12a, it is observed that the maximum number density of the drop size distribution curve shifted from 0.76 to 0.92 mm after an increase in the superficial liquid velocity of 7.64×10-2 m/s from 4.24×10-2 m/s. The drop size distribution curve shifted from to 1.25 mm after an increase in the superficial liquid velocity of 0.105 m/s and a further increase in the superficial liquid velocity of 0.120 m/s, it shifted to 1.91 mm of drop diameter. When the volume fraction of kerosene is increased by 15% and 25%, it showed the same trend as shown in Figure 7.13a and 7.14a. Figure 7.12b shows the number density curve of drop size by increasing the gas velocity from 0.84×10-2 m/s to 2.54×10-2 m/s. It is seen that the size distributions of drops with the kerosene-water system at higher superficial gas velocity are higher than that at the lower superficial gas velocity with an increase in the gas velocity, the drop coalescence increases in the column. Figure 7.12b represents the number density curve of drop size in the presence of 5% kerosene-water at different superficial liquid velocity and, at a constant gas velocity of 0.0254 m/s. From Figure 7.12b, it is observed that the maximum number density of the drop size distribution curve shifted from 1.10 to 1.30 mm after an increase in the superficial liquid velocity of 7.64×10-2 m/s from 4.24×10-2 m/s. The drop size distribution curve shifted to 1.89 mm after an increase in the superficial liquid velocity of 0.105 m/s and a further increase in the superficial liquid velocity of 0.120 m/s, it shifted to 2.49 mm drop diameter.
When the volume fraction of kerosene is increased by 15% and 25%, it showed accordingly as is shown in Figure 7.13b and 7.14b.
0.00 0.31 0.62 0.93 1.24 1.55 1.86 2.17 2.48 0
20 40 60
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(a)
0.5 1.0 1.5 2.0 2.5 3.0
0 10 20 30 40 50 60 70
80 usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(b)
Figure 7.12: Variations of drop size distribution with superficial liquid velocity for 5% (v) kerosene at (a) usg = 0.84×10-2 m/s, (b) usg = 2.544×10-2 m/s
0.4 0.8 1.2 1.6 2.0 2.4 2.8
0 10 20 30 40 50 60 70 80
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(a)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
0 20 40 60 80
100 u
sl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(b)
Figure 7.13: Variations of drop size distribution with superficial liquid velocity for 15% (v) kerosene at (a) usg = 0.84×10-2 m/s, (b) usg = 2.544×10-2 m/s
0.5 1.0 1.5 2.0 2.5 3.0 0
20 40 60 80
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05×10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(a)
1.0 1.5 2.0 2.5 3.0 3.5 4.0
0 10 20 30 40 50 60 70 80 90 100
usl= 4.24×10- 2 m/s usl= 7.64×10- 2 m/s usl= 1.05v10- 1 m/s usl= 1.20×10- 1 m/s
Number density %
dd (mm)
(b)
Figure 7.14: Variations of drop size distribution with superficial liquid velocity for 25% (v) kerosene at (a) usg = 0.84×10-2 m/s, (b) usg = 2.544×10-2 m/s