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X. Li et al.
Introduction
With the rapid development of chemical engineering, metallurgy, energy, and other
industrial processes, the emissions of smelting gas increase year by year. Industrial
waste gases usually contain a certain amount of sulfide, nitride, carbon dioxide and
fine particles. The fine particulate matter (aerodynamic diameter below 2.5 µm,
PM2.5) in the flue gas has a large specific surface area and is easy to absorb toxic
substances, such as various heavy metals and polycyclic aromatic hydrocarbons [1,
2]. Once fine particulate matter accumulates in human lungs, it may cause serious
respiratory diseases. With the strengthening of people’s environmental awareness,
the problems of industrial flue gas purification and dust removal have been paid more
and more attention.
Wet dedusting is a method of capturing dust by liquid nets, films and droplets in
the process of contacting and mixing between dusty airflow and liquid. The reasons
why the liquid can catch dust flying in the air may be the inertial collision, diffusion,
gravity, interception, etc. [3–6]. Wet dedusting technology can not only remove more
than 0.1 µm of fine particles, especially hydrophilic dust, but also can absorb a variety
of harmful gases, such as SO 2 , so it is widely used in industrial dust removal processes
[7–10]. Although wet dedusting technology has been widely used, its complete and
accurate dedusting mechanism has not been reported.
As a typical wet dedusting technology, the reverse spray scrubber utilizes the
intense collision between the high-speed flue gas and liquid jet to form the steady
foaming layer. The fine particles in the air are intercepted by the foaming layer and
are wrapped by turbulent liquid film and flow into the collecting tank, to achieve the
purpose of dust removal. The dust removal mechanism is the collision and mixing
between liquid droplets or films and fine particles, and the trapping process involves
a quite complex gas–liquid-solid multiphase flow problem [11, 12].
There have been some reports on hydrodynamics and parameter optimization for
dynawave washing and reverse spray washing technologies. Li et al. [13] obtained
the empirical correlations of liquid trajectory height and resistance through theoretical analysis and many experimental investigations, which provides an important
theoretical basis for the application of dynawave scrubber. Zhou et al. [14] studied
the hydrodynamic characteristics of the dynawave device, and the gas-liquid flow
regimes were divided into foaming, laminar, bubbly and atomization flows. The
correlation that can predict the pressure drop was also obtained. Huang et al. [15]
found the foaming flow is beneficial to dust removal and the dedusting efficiency
can be up to 99%. The scrubber with the diameter of 55 mm achieved the desulfurization efficiency at 89% under the optimum operation conditions. Wang et al.
[16] investigated the relationship between the L/G (the ratio of liquid flow rate to
gas flow rate), liquid velocity, gas velocity and the dust collection rate. The pressure loss of the dynawave scrubber was less than 1/3 of that of venturi with the
same dust removal efficiency. Chen et al. [11] developed a new washing nozzle with
three liquid inlets and investigated its hydromechanical properties and gas–liquid
two-phase mass transfer performance in the reverse jet scrubber.
X. Li et al.
Introduction
With the rapid development of chemical engineering, metallurgy, energy, and other
industrial processes, the emissions of smelting gas increase year by year. Industrial
waste gases usually contain a certain amount of sulfide, nitride, carbon dioxide and
fine particles. The fine particulate matter (aerodynamic diameter below 2.5 µm,
PM2.5) in the flue gas has a large specific surface area and is easy to absorb toxic
substances, such as various heavy metals and polycyclic aromatic hydrocarbons [1,
2]. Once fine particulate matter accumulates in human lungs, it may cause serious
respiratory diseases. With the strengthening of people’s environmental awareness,
the problems of industrial flue gas purification and dust removal have been paid more
and more attention.
Wet dedusting is a method of capturing dust by liquid nets, films and droplets in
the process of contacting and mixing between dusty airflow and liquid. The reasons
why the liquid can catch dust flying in the air may be the inertial collision, diffusion,
gravity, interception, etc. [3–6]. Wet dedusting technology can not only remove more
than 0.1 µm of fine particles, especially hydrophilic dust, but also can absorb a variety
of harmful gases, such as SO 2 , so it is widely used in industrial dust removal processes
[7–10]. Although wet dedusting technology has been widely used, its complete and
accurate dedusting mechanism has not been reported.
As a typical wet dedusting technology, the reverse spray scrubber utilizes the
intense collision between the high-speed flue gas and liquid jet to form the steady
foaming layer. The fine particles in the air are intercepted by the foaming layer and
are wrapped by turbulent liquid film and flow into the collecting tank, to achieve the
purpose of dust removal. The dust removal mechanism is the collision and mixing
between liquid droplets or films and fine particles, and the trapping process involves
a quite complex gas–liquid-solid multiphase flow problem [11, 12].
There have been some reports on hydrodynamics and parameter optimization for
dynawave washing and reverse spray washing technologies. Li et al. [13] obtained
the empirical correlations of liquid trajectory height and resistance through theoretical analysis and many experimental investigations, which provides an important
theoretical basis for the application of dynawave scrubber. Zhou et al. [14] studied
the hydrodynamic characteristics of the dynawave device, and the gas-liquid flow
regimes were divided into foaming, laminar, bubbly and atomization flows. The
correlation that can predict the pressure drop was also obtained. Huang et al. [15]
found the foaming flow is beneficial to dust removal and the dedusting efficiency
can be up to 99%. The scrubber with the diameter of 55 mm achieved the desulfurization efficiency at 89% under the optimum operation conditions. Wang et al.
[16] investigated the relationship between the L/G (the ratio of liquid flow rate to
gas flow rate), liquid velocity, gas velocity and the dust collection rate. The pressure loss of the dynawave scrubber was less than 1/3 of that of venturi with the
same dust removal efficiency. Chen et al. [11] developed a new washing nozzle with
three liquid inlets and investigated its hydromechanical properties and gas–liquid
two-phase mass transfer performance in the reverse jet scrubber.