Experimental Study on Dust Removal Performance …
43
The classification efficiency experiment uses a wet sampling method. Also under
the condition of isokinetic sampling, a certain amount of gas is sucked into the gas
scrubber, and the particles are left in the water. Using a laser particle size analyzer,
the particle size distribution can be obtained. The formula of classification efficiency
as follows [14]:
η i = 1 − (1 − η)
g 1i
g 0i
(3)
where η i : classification efficiency, %; η: dust removal efficiency, %; g 0i : the proportion of particle size i in the inlet dust, %; g 1i : the proportion of particle size i in the
outlet dust, %.
Results and Discussion
Flow Patterns and Load Performance
As shown in Fig. 3, adjusting the axial and tangential liquid flow ratio (A/T ) of the
nozzle and flow rate of gas and liquid will result in four different flow patterns.
When a laminar flow pattern is formed in the washing zone, as shown in Fig. 3a,
the thickness of the liquid film is small and the spray height of the liquid is low, so
the pressure drop of the gas phase through the liquid layer is not large. Since both
the liquid flow rate (L) and the gas flow rate (G) are low, it is difficult to provide
momentum for forming a stable foam zone in either the gas phase or the liquid
phase. Therefore, the gas–liquid two-phase flow is separated at this time, and the
mass transfer effect between the two phases is not ideal.
It can be seen from Fig. 3b that increasing the L and G begins to form a foam flow
pattern . At this moment, the liquid surface is turbulent at high speed, and a stable
foam layer can be seen on the wall of the washing pipe. At this stage, the gas–liquid
two-phase momentum in the foam zone reaches an equilibrium state. After the gas–
liquid two-phase violently collide, a strong turbulent foam zone is generated. This
area increases the contact area between the gas and the liquid, and at the same time
strengthens the gas–liquid phase. Due to the good mass transfer effect, the foam area
is an ideal operating area.
It can be seen from Fig. 3c that when the gas flow rate is large, the liquid–gas flow
rate ratio (L/G) is significantly reduced. At this stage, an atomized flow pattern is
formed. The end surface of the liquid flow is directly washed away by the high-speed
airflow, and the liquid in the entire washing pipe is in the form of finely atomized
droplets, and jet height is significantly reduced. The main reason is that the gas flow
energy is obviously greater than the liquid flow energy, and the liquid flow is directly
blown away by the gas quickly, so the gas stays in the liquid layer for a short time
and the mass transfer effect between gas and liquid is not good.
43
The classification efficiency experiment uses a wet sampling method. Also under
the condition of isokinetic sampling, a certain amount of gas is sucked into the gas
scrubber, and the particles are left in the water. Using a laser particle size analyzer,
the particle size distribution can be obtained. The formula of classification efficiency
as follows [14]:
η i = 1 − (1 − η)
g 1i
g 0i
(3)
where η i : classification efficiency, %; η: dust removal efficiency, %; g 0i : the proportion of particle size i in the inlet dust, %; g 1i : the proportion of particle size i in the
outlet dust, %.
Results and Discussion
Flow Patterns and Load Performance
As shown in Fig. 3, adjusting the axial and tangential liquid flow ratio (A/T ) of the
nozzle and flow rate of gas and liquid will result in four different flow patterns.
When a laminar flow pattern is formed in the washing zone, as shown in Fig. 3a,
the thickness of the liquid film is small and the spray height of the liquid is low, so
the pressure drop of the gas phase through the liquid layer is not large. Since both
the liquid flow rate (L) and the gas flow rate (G) are low, it is difficult to provide
momentum for forming a stable foam zone in either the gas phase or the liquid
phase. Therefore, the gas–liquid two-phase flow is separated at this time, and the
mass transfer effect between the two phases is not ideal.
It can be seen from Fig. 3b that increasing the L and G begins to form a foam flow
pattern . At this moment, the liquid surface is turbulent at high speed, and a stable
foam layer can be seen on the wall of the washing pipe. At this stage, the gas–liquid
two-phase momentum in the foam zone reaches an equilibrium state. After the gas–
liquid two-phase violently collide, a strong turbulent foam zone is generated. This
area increases the contact area between the gas and the liquid, and at the same time
strengthens the gas–liquid phase. Due to the good mass transfer effect, the foam area
is an ideal operating area.
It can be seen from Fig. 3c that when the gas flow rate is large, the liquid–gas flow
rate ratio (L/G) is significantly reduced. At this stage, an atomized flow pattern is
formed. The end surface of the liquid flow is directly washed away by the high-speed
airflow, and the liquid in the entire washing pipe is in the form of finely atomized
droplets, and jet height is significantly reduced. The main reason is that the gas flow
energy is obviously greater than the liquid flow energy, and the liquid flow is directly
blown away by the gas quickly, so the gas stays in the liquid layer for a short time
and the mass transfer effect between gas and liquid is not good.