
==== Front
ACS Omega
ACS Omega
ao
acsodf
ACS Omega
2470-1343
American Chemical Society

10.1021/acsomega.4c06500
Article
Effect of High-Voltage Electrostatic Precipitator Dust Collection Plate Structure on Collection Efficiency
https://orcid.org/0009-0004-7142-9231
Ning Liwei *†‡
Wang Nan †
Fu Jun †‡
Ma Yi †
Gu Shuo †
Cheng Milan †
† College of Mechanical and Engineering, Shaoyang University, Shaoyang 422000, China
‡ Key Laboratory of Hunan Province for Efficient Power System and Intelligent Manufacturing, Shaoyang University, Shaoyang 422000, China
* E-mail: wn99282022@163.com.
20 08 2024
03 09 2024
9 35 3739637407
14 07 2024
15 08 2024
04 08 2024
© 2024 The Authors. Published by American Chemical Society
2024
The Authors
https://creativecommons.org/licenses/by-nc-nd/4.0/ Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).

To investigate the effect of changes in the dust collector structure on the flow field and electric field distribution resulting from the secondary flow generated by the corona discharge in the collector coupled with the main flow and to improve the dust collection efficiency of the ESP, a folding plate design has been adopted. A multiphysics-coupled corona discharge and flow field numerical model was analyzed to analyze the internal flow and electric field characteristics of linear flat plates and folded plates with three different pole configurations. The study indicates that the dust collecting plate’s structure significantly affects the dust collector’s internal flow field and electric field distribution within the dust collector. The near-plate electric field and flow field inside the folded plate type are superior to those of the linear flat electrostatic precipitator. With the augmentation of the inlet velocity, the ionic wind disturbance on the flow field inside the electrostatic precipitator channel gradually decreases. Additionally, the folding plate has a certain inhibitory effect on the influence of the ionic wind. At an inlet velocity of 0.5 m/s, the speed near the folding plate is approximately 20% lower than that of the traditional linear flat plate. The folding plate can effectively reduce the flow velocity near the dust collection plate, thereby reducing the occurrence of particle re-entrainment and improving dust removal efficiency. By comparing the speed at the center line of the plate and near the plate, it is obvious that the speed of model B decreases significantly, and as the number of discharge electrodes increases, the speed decreases more obviously. At the same time, when the dust collection efficiency of the two models was compared, it was found that the working efficiency of the B model has been significantly improved, among which the B3 model has the best dust collection effect.

Shaoyang University 10.13039/501100004068 CX2023SY082 Natural Science Foundation ofÃ&#130;Â Hunan Province NA 2023JJ50262 Natural Science Foundation ofÃ&#130;Â Hunan Province NA 2022JJ58025 document-id-old-9ao4c06500
document-id-new-14ao4c06500
ccc-price
==== Body
pmc1 Introduction

Since the 1960s, the rapid development of the global economy has led to a series of environmental issues. Air pollution has a direct impact on human survival and development, and fine particulate matter emissions are closely linked to human health.1 Waste incineration and thermal power generation are examples of production processes that produce a large number of exhaust particles. Electrostatic precipitator technology has rapidly developed to solve the problem of separating and capturing dust during the production process.2 Currently, the most widely used dust removal technologies include mechanical dust removal, bag dust removal, wet dust removal, and electrostatic dust removal.3 Compared to other dust removal technologies, electrostatic dust removal technology is known for its high efficiency, ease of management, and low energy consumption.4 Therefore, it has promising development prospects.

Electrostatic precipitators have several advantages, but their further development is restricted by certain factors.5 However, the low charge carried by fine particles greatly disturbs their movement in the electrostatic precipitator due to the fluid, resulting in a dust removal efficiency of only 70% to 80%.6 To enhance the efficiency of dust removal in electrostatic precipitators, researchers have conducted extensive studies. Bacher7 measured the dust removal efficiency of wire-tube electrostatic precipitators with electrodes of different shapes. The study found that the dust collector had the highest working efficiency when the power supply voltage was just below the breakdown voltage. Additionally, the dust collector with long spikes in the experimental group had the highest efficiency and lowest energy consumption for electrode dust removal. Wang et al.8 studied the electric fluid flow induced by corona discharge in a wire-plate dust collector using particle image velocimetry (PIV). Research has shown that the ionic wind can be seen in the flow streamlines near the collection plate that bend toward the discharge electrode, and as the voltage increases, a jet-like flow structure is formed from the wires toward the electrode plate. Research by Ning et al.9 shows that as the voltage increases, the effect of ionic wind in the flow field gradually intensifies, thereby forming a symmetrical double helix structure within the flow field state of the channel. Liu et al.10 used expansion plates to modify the collection electrode. The study demonstrated that the expansion plate structure had the ability to alter the distribution of electric and flow fields in the electrostatic precipitator, leading to a significant improvement in the dust removal efficiency. Wang et al.11 have shown that the dust collector channel’s near-wall area flow velocity is related to the particle re-entrainment effect. The greater the flow velocity, the more significant the particle re-entrainment effect. Modifying the structure of the dust collection pole can alter the distribution of the electric and flow fields near it, which in turn affects the dust removal efficiency.12 Due to the complex internal structure of the dust collector, the complex turbulence near the dust collection electrode under high voltage cannot be directly observed. The influence of the electrode structure on the electric fluid state inside the dust collector is difficult to quantify.13 Numerical simulation methods are utilized to study data such as the electric fluid state and flow field changes under working conditions, providing a basis for experimental and theoretical analysis.

Electrostatic precipitation involves a coupling of multiple physical processes, including electric fields, flow fields, and particle motion.14 To improve dust collection efficiency, researchers have primarily focused on the impact of factors such as high-voltage power supply type, discharge electrode shape, and wet or soot conditioning on dust removal efficiency.15 However, the geometry of the dust collection plate and the disruption caused by the flow field near the dust collection pole also play a crucial role in the collection of fine particles.16 Numerous studies have endeavored to ascertain numerical solutions to the corona problem across various ESP configurations, notably exploring the impact of the wire-to-plate geometry. Variations in geometry significantly alter the internal electric field’s distribution and intensity, thereby influencing operational efficiency.10,17 Zhu et al.18 investigated the superiority of corrugated plate electrostatic precipitator for particle capture.

This paper designs dust collectors with linear and corrugated plate structures for research. To study the electric and flow field characteristics within the channel of a bipolar electrostatic precipitator, a numerical model coupling corona discharge and flow field physics was created. The effects of different discharge electrode positions on particle capture efficiency were also compared.19,20

2 ESP Modeling

2.1 Experimental Principle

The electrostatic precipitator is mainly composed of a dust collection plate and a discharge electrode,21−23 as shown in Figure 1. Its working principle is roughly as follows: the electrode wire is connected to the power supply, creating a high-voltage electric field from it to the dust collection plate. Corona discharge occurs nearby, causing the air to ionize. When the particles pass through the corona area under the action of airflow, the charged ions combine with the dust particles and migrate toward the dust collecting plate driven by the electric field force and are finally captured by the dust collecting plate. It achieves gas–solid separation and achieves the purpose of dust collection and purification.24

Figure 1 ESP working principle diagram.

The ESP computational model comprises corona discharge, gas flow, particle charge, and transport.25,26 Therefore, the equations governing the system include those for the electric field, space charge, fluid dynamics, particle trajectories, and charge. This experiment monitors changes in electric field data by altering the shape of the electrode plate and wind speed. Through comparative analysis of data, we finally concluded the relationship between the impact of electrostatic precipitators on particle collection efficiency.27

2.2 Corona Model

It is assumed that the distribution of the electric field characteristics remains unaffected by charged particles. Poisson’s equation and the current continuity equation describe changes in the electric field. This Poisson equation is as follows:1

The continuity equations are as follows:2

3

4

In the formula, V is the electric potential, ρ is the space charge density, ε0 is the dielectric constant in vacuum, J is the current density, and the empirical formula Peek’s law is used to calculate the initiation voltage value of the circular electrode corona discharge, The relevant equations are as follows:5

In the formula, Es is the electric field intensity on the electrode surface, E0 is the breakdown electric field intensity constant, which is generally considered to be 3.1 × 106 V/m, a is the dimensionless surface parameter, δ is the relative gas density, and r0 is the electrode radius. From this, the corona discharge initiation voltage at different radii is calculated according to this law.28

2.3 Flow Field Model

In the simulation test, the fluid flow inside the ESP is treated as incompressible flow due to the significantly lower flow velocity in the ESP channel compared to the speed of sound.29 Therefore, an isothermal, low-flow turbulence model is selected during simulation, that is, the turbulence model type is RANS and the standard k–ε model.30 The relevant equations are as follows:6

The formula includes constants C1, C2 and σε with values of 1.44, 1.92, and 1.3, respectively. The turbulent viscosity coefficient is represented by ut, while uj and xj represent the velocity component and coordinate direction, respectively. The k–ε model, where k represents turbulent kinetic energy and ε represents turbulent dissipation rate, conforms to the following transport equation:7

In the formula, G is the turbulent shear stress, σk is a constant, and its value is 0.09.

2.4 Particle Motion and Charging Model

The position of a moving particle can be determined by solving the second-order motion equation of the particle position vector component, as described in Newton’s second law of motion. The governing equation is as follows:8

9

In the formula: q is the position of the particle (m), v is the speed of particle movement (m/s), mp is the mass of the particle (kg), Ft is the resultant force exerted on the particle (N).

The LAWLESS model is employed for calculating the accumulated charge on the particles.31 The calculation equation is as follows:10

11

12

13

14

In the formula: v is the dimensionless particle charge, w is the dimensionless electric field Strength, qp is the particle charge (C), e is the charge of the electron (1.6 × 1019 C), dp is the particle diameter (m), kB is Boltzmann’s constant (1.3806 × 10–23 J·K–1), T is the thermodynamic temperature (K), εp is the particle dielectric constant, τ is the dimensionless charging time, where ρion is the ion charge density (C·m–3), and kion is the ion mobility (m2·V–1·s–1), t is the actual charging time (s).

The following formula is used to calculate the collection efficiency and effective migration speed of particles:15

16

The model solution is divided into two steps. The first step is the steady-state calculation, which calculates electric fields, charge transport, turbulence fields, and multiphysics field coupling.32 Based on the results of the steady-state calculation, the second step of the transient calculation is performed to calculate the fluid flow particle tracking.33 Finally, the movement trajectories of particles in the electric and flow fields and the dust removal efficiency are obtained.

2.5 Discharge Structure

Most electrostatic precipitators (ESP) in practical applications today are wire plate structures, and the structure of wire plate electrostatic precipitators is symmetrical.34 Taking the multiline plate dust collector as an example, select and intercept the appropriate plane to build the model, and simplify the three-dimensional dust collector into a two-dimensional model.35 This simplification primarily aims to enhance the computational efficiency and ease of model analysis. Simplifying the model reduces its complexity and improves the calculation efficiency of the simulation analysis. Additionally, the 2D model offers a more intuitive and convenient approach for processing image data such as particle trajectories and airflow distribution. Figure 2. shows the three-dimensional structural diagram of the line plate and folding plate electrostatic precipitators.

Figure 2 Three-dimensional structure of the linear plate and folding plate dust collectors.

The dust collector consists of four main components: the inlet on the left, the upper and lower dust-collecting plates, the discharge electrode in the middle, and the outlet on the right. To aid in problem analysis, the coordinates are defined as follows: the origin is the center of the electrode facing the entrance; the X-axis is parallel to the plate; the Y-axis is perpendicular to the dust collection plate; and the main plane for analysis is the XY cross-section.

To investigate the impact of plate types and discharge electrode spacing on the internal flow field and dust removal performance of a dust collector, two types of dust collectors were used: line-to-traditional plate and line-to-folding plate. Additionally, different discharge electrode quantities were tested and labeled as models A and B, as depicted in Figure 3.

Figure 3 Two-dimensional model of dust collector with different dust collection plates

The electrode radius was set to 1 mm; the length of the simulation area was set to 500 mm; the width of the left entrance was set to 100 mm; and the width of the right exit was set to 100 mm. For Model B, the height difference between the inner and outer folding panels at the entrance and exit positions is 5 mm. The folding angle of the line board is 117°, and the length of the long folding board is 20 mm. The height of the inner and outer panels is 10 mm, and the width is 5 mm, as shown in Figure 3. Table 1 lists the ESP operating parameters. The B1 model has an electrode facing the center of the long-folded plate and contains three discharge electrodes, and the B2 model has four discharge electrodes. The B3 model contains five discharge electrodes. The discharge electrode positions are in the same relationship as the discharge electrode positions of the line plate dust collector. The positions of the electrodes at the left and right ends are fixed, and the distance from the entrance and exit is 100 mm.

Table 1 Operating Parameters

Parameter (unit)	Value	Parameter (unit)	Value	
Plate length (mm)	500	Temperature (K)	293.15	
Electrode diameter (mm)	1	Pressure (atm)	1	
Voltage (kV)	40	Particle diameter (μm)	0.1–1	
Gas velocity (m/s)	0.2, 0.5, 1, 1.2	Particle density (kg/m3)	2200	

Since the ESP model is a multifield coupling numerical model, its accuracy must be verified by comparing the simulation results for the electric field, flow field, and collection efficiency. Figure 4 presents the potential variation from the discharge electrode to the dust collecting plate. Comparison with Penney’s experimental results indicates that the model used in this study is consistent with the simulated potential distribution results.36 Additionally, the changes in the flow field and the dust collection efficiency outcomes are also in agreement with the experimental data.37

Figure 4 Comparison of numerical results with experimental data in terms of the (a) electric field, (b) flow field, and (c) collection efficiency.

2.6 Mesh Division and Boundary Condition Settings

In the simulation, the electrode has a small radius of curvature, resulting in high field intensity. To improve simulation accuracy, the mesh around the electrode is refined in the 2D model, as shown in Figure 5a. When assessing the dust collector’s efficacy in dust removal, it is crucial to account for factors like the electric field intensity and the wind speed ahead of the plate. This areas near the plate boundary and around the discharge electrode are densely processed, as depicted in Figure 5b. This internal grid of the ESP is divided according to the methods of controlling the plasma physical field, as shown in Figure 5c. The mesh near the folding plate of the folding plate dust collector is densely processed, and the overall mesh is divided, as illustrated in Figure 5d.

Figure 5 Schematic diagram of mesh division. (a) Around the discharge electrode; (b) Near the dust collecting plate; (c) The grid at the entrance of the line plate; (d) Grid at the entrance of the folding plate.

The dust collector inlet is designed for full flow, while the outlet is designed to maintain static pressure to prevent backflow. Both the inlet and outlet are electrically neutral with zero surface charge density. The boundary conditions for the simulations are listed in Table 2. Dirichlet boundary conditions are applied at the interface between the dust collection plate and the discharge electrode.

Table 2 Boundary Conditions

Position	Airflow	Particle	Electric field	Space charge	
Inlet	Velocity	Velocity			
Outlet	Outflow	Disappear			
Discharge electrode	Wall	Bounce back	40 kV	ρ0	
Plates	Wall	Freeze	0		

3 Results and Discussion

3.1 Potential Distribution

The dust collector’s efficiency is affected by the distribution of electric potential. For instance, when the applied voltage is 40 kV, the potential distribution inside the dust collector of model A2 is like that of model B2, as shown in Figure 6.

Figure 6 Internal potential distribution of two dust collectors. (a) Two-dimensional distribution of electric field intensity. (b) Linear changes in electric field.

The two electrostatic precipitator models exhibit a decreasing potential magnitude along the electrode line toward the dust-collecting plate. A high electric field area is concentrated in the proximity of the electrode. Therefore, the electric potential perpendicular to the dust collecting plate changes significantly. The electric potential inside the dust collector is distributed in an elliptical shape. The findings indicate that the electric field intensity and potential changes are minimal in the vicinity of the dust collection plate, while they are large near the discharge electrode. Model B shows different potentials for the upper and lower plates due to the varying distances from the folding plate’s upper and lower bottom plates to the discharge electrode. Furthermore, the change in the electric potential distribution of the folded plate at 5000 V is intricate. The electric potential varies with the modification of the plate’s shape, which in turn affects the deflection of particles in the electric field.

3.2 Space Charge Density Distribution

The distribution of the space charge density significantly influences the charging and collection of dust particles in the collector. The Figure 7 shows the analysis of the A2 and B2 models.

Figure 7 Space charge density distribution in the A2 and B2 model dust collectors. (a) Two-dimensional distribution of space charge density. (b) Space charge density exhibits a linear distribution.

Figure 7 shows that the charge in space is concentrated near the electrode. Model A has an elliptical distribution with peaks in the four small ellipses above and below the pole line directly opposite the pole plate. In Model B, the shape of the electrode plate has changed, resulting in the charge being concentrated in eight overlapping small ellipses symmetrically above and below the electrodes. The peak value of Model A is 6.40 × 10–4 C/m–3, while the peak value of Model B with the folded plate is slightly lower at about 6.21 × 10–4 C/m–3. The charge distribution on the dust collector plate of model A is highest at the electrode directly opposite to the pole plate and then decreases in a Gaussian-like distribution toward both sides. The area nearest the dust collector plate exhibits the highest charge. In particular, the space charge density will be higher on the inside than on the outside. The distribution of space charge density inside model B is more uniform than that of model A. In addition, the B model has a wider expansion range of the space charge density, which can more effectively improve the charging effect of the particles, which, in turn, affects the performance of the ESP.

3.3 Flow Field Distribution

The dust removal process involves a gas–solid two-phase flow movement, where dust particles are charged and separated from the gas flow by multiple forces. Therefore, the gas flow within the dust collector notably impacts the efficiency of dust particle collection. The ionic wind phenomenon, produced by the rapid movement of ions during the corona discharge process, also greatly influences the gas flow in the dust collector. Ionic wind movement in the electric field space produces a spiral vortex. The vortex prolongs the particles’ residence time in the electric field, promoting particle charge and collision chances and thus facilitating the coagulation process. However, the presence of ionic wind flow can also disrupt the internal flow field of the dust removal space and wash the dust collection plate, leading to particle re-entrainment and reduced dust removal efficiency. Using A2 and B2 models as an example, the study yielded the following results.

As illustrated in Figure 8, the inlet flow velocity is 0.2 m/s and the voltage is 40 kV. The ionized wind generates a series of complex turbulence phenomena inside the dust collector of two different structures. Due to the lower flow rate, the particles are more affected by the ionized wind. Four ionized wind vortices are generated near the electrodes, and they exhibit symmetry along the x-axis. The lower wind speed passing through the collection area is favorable for the particles to be adsorbed on the dust collection plate, reducing the likelihood of particle re-entrainment formation, and effectively improving the performance of the ESP.

Figure 8 Flow field of A2 and B2 model dust collector (0.2 m/s).

As the inlet flow velocity increases to 0.5 m/s while keeping all other conditions constant, the influence of the ionic wind inside the collector diminishes. This is shown in Figure 9. The maximum wind speed in the linear plate dust collector exceeded that of the improved folded plate dust collector. Both plate types exhibit their maximum wind speeds near the electrode. A small turbulent vortex is formed near the dust collecting plate of the folded plate dust collector, but the flow velocity near the electrode plate is only 20% of the mainstream flow velocity or even lower. Due to the weak flow rate, it can effectively suppress the particle re-entrainment phenomenon and enhance the dust removal effect.

Figure 9 Flow field of A2 and B2 model dust collector (0.5 m/s).

Figure 10 shows the internal flow field of the dust collector with an increased inlet flow rate of 1 m/s. The main flow inside the dust collector is approximately laminar at this point, and the impact of the ionized wind on the flow field is diminished. And A model dust collector did not have any turbulent vortices, while the B model dust collector had vortices only in some of the grooves. The straight plate dust collector has a higher maximum air velocity compared with the folded plate. However, the folded plate has a lower average flow velocity near the pole plate. This region increases the residence time of particles in the dust collector and effectively reduces the occurrence of particle re-entrainment lifting due to the lower velocity.

Figure 10 Flow field of A2 and B2 model dust collector (1 m/s).

Figure 11 shows that the flow field change between the online flat plate and the folded plate is more complex when combined with the velocity change at the centerline position of the A2 and B2 electrode plates. Overall, the wind speed on the centerline follows an inverted double ditch shape, reaching its minimum value parallel to the discharge electrode. This occurs because the electric field force is strongest at this point and the flow field force it receives is in the opposite direction, resulting in the smallest velocity vector sum. The velocity at the near-plate of model A is much higher than that at the near-plate of model B. The space between the upper and lower pole plates of the folded plate is also larger, and the velocity is lower. Obviously, the velocity change of the B-type structure is smaller, which effectively prevents the escape of particles and the occurrence of particle re-entrainment raising and ultimately improves the dust removal efficiency of the ESP.

Figure 11 Velocity change diagram at the center line of the plate.

3.4 Data Analysis of 10 mm in Front of the Board

The collector exposes particles to both the force of the electric field and fluid resistance during movement. The force on charged particles in the x direction increases with the larger initial velocity of the flow field in that direction. This results in a shorter time for the particles to pass through the dust collection area. Moreover, the strength of the electric field force acting on particles toward the movement of the dust collection plate depends on the y-direction component of the field. A stronger electric field in the y-direction enhances the force on charged particles in that direction, thereby promoting their movement toward the dust collection plate.

At an applied voltage of 40 kV and an inlet wind speed of 0.5 m/s, it is evident from the velocity change curves 10 mm in front of the two electrostatic precipitator plates (the ab line of model A and the cd line of model B), that changing the structure of the dust removal plate has a great impact on the speed change. Comparing the velocity analysis of the three linear plate structures at 10 mm in front of the plate, as shown in Figure 12, model A1 has the largest range of velocity variation with a maximum velocity of 1.35 m/s, followed by model A3 with a maximum velocity of 1.23 m/s, and model A2 has the smallest peak velocity of 1.2 m/s. Although the peak speed of A3 is higher than that of A2, the speed drop range of the A3 model is wider when considering the entire speed change. Its exit speed is the lowest, only 0.62 m/s. The peak velocities occur consistently at the midpoint between the two electrodes. The velocity in the flow field increases first and then decreases. The velocity is the smallest at the point perpendicular to the discharge electrode, and the velocity reaches the maximum at the midline of the two discharge electrodes. Since the electric field force at the vertical line of the discharge electrode is perpendicular to the fluid drag force on the particles, the vector sum of the forces they are subjected to is relatively small. The larger the range of velocity change of the particles as they pass through the dust collection area, the more time the gas must pass through the dust collection area. This is favorable for the particles to become fully charged, move toward the dust collection plate, and finally be collected.

Figure 12 Model A velocity near the plate.

As shown in Figure 13, the velocity peak of B3 is the largest, with a maximum velocity of 1.2 m/s, the maximum velocity of the B2 model is 1.14 m/s, and the velocity peak of the B1 model is the smallest, with a peak velocity of 1.10 m/s, when comparing the velocity analysis at 10 mm in front of the three folded plate structures. While the velocity peak of B3 is the largest, from the perspective of the whole velocity change, the velocity change range of the B3 model is wider and its exit velocity is the smallest, at 0.80 m/s. Compared with the exit velocity of B2 and B3, the velocity of B2 is 0.92 m/s, while that of B1 is 1.0 m/s. The velocity variation in model B also follows the rule, albeit with some complexity. Notably, the peak velocity occurs between the two discharge electrodes due to the influence of the folded plate’s alteration on the internal flow field, which in turn affects the flow field of model B. The velocity of model B3 has a more obvious decreasing trend, which indicates that the time of particle flow through the dedusting area is greatly increased, which is conducive to improving the dedusting efficiency.

Figure 13 Model B velocity near the plate.

A comparative analysis of the two models indicates that variations in the distance between discharge electrodes stemming from differences in the pole plate structure and the number of discharge electrodes result in differences. Moreover, changes in the pole plate structure also affect the strength of the electric field, which alters the electric field force acting on charged particles within the field. From Figure 13 and 14, the main flow velocity in the dust collector of model A is higher, while the main flow velocity of the modified model B is lower than that in the wire-plate dust collector in both cases, the B model outperforms the A model in optimizing the flow field. The particle velocity changes significantly, with a wider range and formation of a low-speed region. It improves the time required for the particles to pass through the dust collection area and greatly reduces the size of the velocity of the particles before they arrive at the pole plate, which is conducive to improving the charging efficiency of the particles, preventing the generation of the problem of particle re-entrainment, and improving the effect of dust collection.

Figure 14 Electric field intensity distribution 10 mm in front of the two model plates.

Comparison of the electric field intensity change curves at 10 mm in front of the two types of ESP plates reveals a significant impact of the pole plate structure on the distribution of electric field intensity. For the linear flat plate dust collector, the electric field intensity distribution peaks near the pole line facing the pole plate and gradually decreases toward the inlet and outlet, respectively. The folded plate is far from the discharging electrodes and decreases then toward the inlet and outlet direction, therefore resulting in the highest electric field intensity closest to the discharge electrode of the folded plate. The wire plate dust collector has a significantly smaller peak electric field intensity than the folded plate dust collector, and it is easier to produce an electric field intensity differential when there is a jump in the electric field intensity. Taking A1 and B1 as an example, the maximum value of the line plate is 6.6 × 105 V/m, while for the folded plate is 8.0 × 105 V/m. The folded plate can significantly increase the dust collector’s dust collection efficiency by increasing the frequency of the electric field intensity leap, which promotes the enlargement of the particles exposed to the electric field force. It can also effectively increase the electric field intensity index in front of the dust collector’s pole plate.

3.5 Analysis of Particle Dust Collection Efficiency

Generally, the particle size distribution of particles in dusty flue gas varies widely, and the trajectories of particles moving under different pole plate configurations are very different. The dust collection efficiency of the collector will be different in different cases due to the different model setting conditions. Figure 15 displays the collection efficiency of the two models at a 1.2 m/s air velocity and 40 kV discharge voltage.

Figure 15 Comparison of the collection efficiencies of models A and B.

The results show that the collection efficiency of different models varies depending on the size of the particles. The electric field force acting on the particles increases with the particle radius, which facilitates easier particle collection by the dust collection plate. Overall, the dust removal efficiency of model B is superior to that of model A. Additionally, the dust removal effect can be enhanced by gradually increasing the number of electrodes in the dust collector. The analysis revealed that the dust collector’s efficiency in collecting dust is affected when the number or spacing of discharge electrodes is changed.

4 Conclusion

Numerical simulation was employed in this experiment to investigate the impact of a novel folding plate design on the velocity field and electric field dynamics within an ESP. The results were compared and analyzed with the traditional linear flat plate ESP. Through the mutual perturbation between ionized wind and mainstream wind speed, the following results were obtained:(1) The novel folding plate ESP has a higher electric field intensity near the plate than the conventional linear flat plate. The intensity of the electric field varies more often in the folding plate, which makes it easier for fine dust particles to enter the collector. The groove area enhances dust charging in the entire flow field area, improving dust collection efficiency. The electric field intensity in the new folding panels varies depending on the number of discharge electrodes. Specifically, an increase in the number of electrodes correlates with a rise in electric field intensity.

(2) As the velocity increases, the mainstream impact of the ionic wind on the precipitator gradually diminishes in both the linear flat plate and folded plate models. In the online flat plate model, the emergence of the ionic wind has symmetrical characteristics. As the speed increases, the turbulent vortex inside the dust collector gradually decreases, and the influence of the ionic wind gradually weakens. When the wind speed reaches a certain threshold, the flow in the channel can be approximated as laminar. The area of the mainstream flow in the folded plate can also be considered laminar. The velocity at the groove in the folded plate is lower, which promotes the adsorption of particulate matter and enhances the efficiency of dust collection.

(3) Folded plates are effective in reducing the air velocity in the vicinity of the ESP plate. The average flow velocity of the folded-plate ESP decreased by approximately 20% compared to that of the linear flat plate at an intake velocity of 0.5 m/s. The reduction effect is more pronounced with an increase in discharge electrodes, with the largest velocity change observed for type B3, and the velocity change being relatively smooth. The folded-plate structure effectively reduces the flow velocity near the dedusting plate, improving the dedusting effect by reducing the reduction of dedusting efficiency caused by particle re-entrainment lifting. The B3 model shows better overall results compared to the B1 and B2 models.

(4) The efficacy of the novel folding plate dust collector in collecting dust surpasses that of the conventional linear flat plate dust collector. Changing the form of the dust collecting plate can lead to changes in the dynamics of the electric field and flow field inside the dust collector, which in turn affects the dust collector’s efficiency. Additionally, increasing the number of discharge electrodes gradually enhances the collection efficiency of the dust collector.

The authors declare no competing financial interest.

Acknowledgments

(1) Natural Science Foundation of Hunan Provincial (2022JJ58025, 2023JJ50262); (2) Graduate Research and Innovation Project of Shaoyang University (CX2023SY082).

Nomenclature

V Electric potential, kV

ρi Space charge density, C/m3

ε0 Permittivity of free space, C/V/m

J Current density, A/m2

ki Ion mobility, m2/V/s

E Electric field strength, V/m

u Gas velocity, m/s

Di Ion diffusion coefficient, m2/s

δ Relative gas density

P Pressure, Pa

T Temperature, K

E0 Onset electric field, V/m

t actual charging time, s

e Electronic charge, 1.6 × 10–19 C

σk Constant

dp Particle diameter, μm

εp Particle dielectric constant

kion ion mobility, m2·V–1·s–1

Nout Number of exported particles

A Collection plate area, m2

Es Dust layer gap breakdown electric field strength, V/m

a Dimensionless surface parameter

r0 Electrode radius, m

εr Relative permittivity of particle

Cd Drag coefficient

η Collection efficiency, %

ut Turbulent viscosity coefficient

uj velocity component, m/s

xj coordinate direction, m

G turbulent shear stress

v speed of particle movement, m/s

mp mass of the particle, kg

qp particle charge, C

q the position of the particle, m

w Effective migration velocity, m/s

kB Boltzmann’s constant, 1.3806 × 10–23 J·K–1

τ Time constant

ρion ion charge density, C·m–3

Nin Number of inlet particles

Q Gas flow, m3/s
==== Refs
References

Andrade R. G. S. A. ; Guerra V. G. Discharge electrode influence on electrostatic precipitation of nanoparticles. Powder Technol. 2021, 379 , 417–427. 10.1016/j.powtec.2020.10.087.
Dong M. ; Zhou F. ; Zhang Y. ; Shang Y. ; Li S. Numerical study on fine-particle charging and transport behaviour in electrostatic precipitators. Powder Technol. 2018, 330 , 210–218. 10.1016/j.powtec.2018.02.038.
Bürger P. ; Riebel U. High temperature coronas in air and flue gas from LPG combustion: Current-voltage characteristics, ion mobilities and free electrons. J. Electrost. 2022, 115 , 103676 10.1016/j.elstat.2022.103676.
Jaworek A. ; Krupa A. ; Czech T. Modern electrostatic devices and methods for exhaust gas cleaning: A brief review. J. Electrost. 2007, 65 (3 ), 133–155. 10.1016/j.elstat.2006.07.012.
Drga J. ; Holubčík M. ; Čajová Kantová N. ; Červenka B. Design of a Low-Cost Electrostatic Precipitator to Reduce Particulate Matter Emissions from Small Heat Sources. Energies 2022, 15 (11 ), 4148 10.3390/en15114148.
Wang Y. ; Gao W. ; Zhang H. ; Huang C. ; Luo K. ; Zheng C. ; Gao X. Insights into the role of ionic wind in honeycomb electrostatic precipitators. J. Aerosol Sci. 2019, 133 , 83–95. 10.1016/j.jaerosci.2019.04.011.
Bacher C. ; Lebedynskyy V. ; Fischer S. ; Riebel U. Discharge electrode geometry and energy efficiency in a one-stage wire-tube electrostatic precipitator operating at high concentrations of submicron liquid aerosol. Environ. Technol. 2020, 41 (16 ), 2096–2108. 10.1080/09593330.2018.1555613.30501585
Wang C. ; Xie Z. ; Xu B. ; Li J. ; Zhou X. Experimental Study on EHD Flow Transition in a Small Scale Wire-plate ESP. Measurement Science Review 2016, 16 (3 ), 134–141. 10.1515/msr-2016-0016.
Ning Z. ; Cheng L. ; Shen X. ; Li S. ; Yan K. Electrode configurations inside an electrostatic precipitator and their impact on collection efficiency and flow pattern. Eur. Phys. J. D 2016, 70 , 1–10. 10.1140/epjd/e2016-60736-2.
Gao W. ; Wang Y. ; Zhang H. ; Guo B. ; Zheng C. ; Guo J. ; Gao X. ; Yu A. Numerical simulation of particle migration in electrostatic precipitator with different electrode configurations. Powder Technol. 2020, 361 , 238–247. 10.1016/j.powtec.2019.08.046.
Wang Y. ; Gao W. ; Zhang H. ; Shao L. ; Wu Z. ; Li L. ; Sun D. ; Zheng C. ; Gao X. Enhanced particle precipitation from flue gas containing ultrafine particles through precharging. Process Safety and Environmental Protection 2020, 144 , 111–122. 10.1016/j.psep.2020.07.005.
Wang Y. ; Gao W. ; Zhang H. ; Yang Z. ; Zhao Z. ; Shao L. ; Sun Z. ; Zheng C. ; Gao X. Significance of ionic wind propulsion on charged particle removal during flue gas purification. Powder Technol. 2022, 410 , 117804 10.1016/j.powtec.2022.117804.
Jaworek A. ; Marchewicz A. ; Sobczyk A. T. ; Krupa A. ; Czech T. Two-stage electrostatic precipitator with co- and counter-flow particle prechargers. J. Electrost. 2017, 87 , 180–194. 10.1016/j.elstat.2017.04.012.
Kasdi A. Computation and measurement of corona current density and V–I characteristics in wires-to-plates electrostatic precipitator. J. Electrost. 2016, 81 , 1–8. 10.1016/j.elstat.2016.02.005.
Gudanov I. S. ; Lebedev A. E. ; Vatagin A. A. Modernization of a High-Performance Electrostatic Precipitator. Chemical and Petroleum Engineering 2022, 57 (11–12 ), 963–965. 10.1007/s10556-022-01031-1.
Jedrusik M. ; Swierczok A. ; Teisseyre R. Experimental study of fly ash precipitation in a model electrostatic precipitator with discharge electrodes of different design. Powder Technol. 2003, 135–136 , 295–301. 10.1016/j.powtec.2003.08.021.
Larsson A.-C. ; Einvall J. ; Sanati M. Deactivation of SCR Catalysts by Exposure to Aerosol Particles of Potassium and Zinc Salts. Aerosol Sci. Technol. 2007, 41 (4 ), 369–379. 10.1080/02786820701203207.
Zhu Y. ; Gao M. ; Chen M. ; Shi J. ; Shangguan W. Numerical simulation of capture process of fine particles in electrostatic precipitators under consideration of electrohydrodynamics flow. Powder Technol. 2019, 354 , 653–675. 10.1016/j.powtec.2019.06.038.
Li J. ; Duan L. ; Chen J. ; Li D. ; Bao S. ; Wang Z. ; Wang J. ; Liao J. Research of the effect of different corrugated dust collection plates on particle removal in electrostatic precipitators. Chem. Eng. Res. Des. 2023, 197 , 323–333. 10.1016/j.cherd.2023.07.006.
Molchanov O. ; Krpec K. ; Horák J. ; Kuboňová L. ; Hopan F. The turbulence consideration in predicting efficiency of electrostatic precipitation for ultrafine aerosols from small-scale biomass combustion. Measurement 2022, 188 , 110412 10.1016/j.measurement.2021.110412.
Qi L. ; Liu M. ; Wang X. ; Li J. ; Zeng F. Inertial Separation of Particles Escaped from Electrostatic Precipitators. ACS Omega 2021, 6 (16 ), 10875–10883. 10.1021/acsomega.1c00624.34056241
Qi L. ; Zhao Z. ; Wang R. ; Gao W. ; Li J. ; Zhang Y. Simultaneous Desulfurization and Denitrification Using La-Ce-V-Cu-ZSM-5 Catalysts in an Electrostatic Precipitator. ACS Omega 2020, 5 (18 ), 10525–10532. 10.1021/acsomega.0c00808.32426610
Xu X. ; Zheng C. ; Yan P. ; Zhu W. ; Wang Y. ; Gao X. ; Luo Z. ; Ni M. ; Cen K. Effect of electrode configuration on particle collection in a high-temperature electrostatic precipitator. Sep. Purif. Technol. 2016, 166 , 157–163. 10.1016/j.seppur.2016.04.039.
Zeng Y. ; Xie R. ; Cao J. ; Chen Z. ; Fan Q. ; Liu B. ; Lian X. ; Huang H. Simultaneous removal of multiple indoor-air pollutants using a combined process of electrostatic precipitation and catalytic decomposition. Chem. Eng. J. 2020, 388 , 124219 10.1016/j.cej.2020.124219.
Xu J. ; Chen P. ; Gu Z. ; Xi J. ; Cai J. Performances of a new type high-temperature tubular electrostatic precipitator with rare-earth tungsten cathode. Sep. Purif. Technol. 2022, 280 , 119820 10.1016/j.seppur.2021.119820.
Zhang J. ; Wang J. ; Jiang Z. ; Xu D. Trapping PM2.5 particles from electrostatic precipitator equipped with magnetic field under different gas velocities. Process Safety and Environmental Protection 2022, 158 , 115–122. 10.1016/j.psep.2021.11.035.
Zheng C. ; Zhang H. ; Liu X. ; Wang Y. ; Gao W. ; Zheng H. ; Sun D. ; Gao X. Effect of dust layer in electrostatic precipitators on discharge characteristics and particle removal. Fuel 2020, 278 , 118335 10.1016/j.fuel.2020.118335.
Gao M. ; Zhu Y. ; Yao X. ; Shi J. ; Shangguan W. Dust removal performance of two-stage electrostatic precipitators and its influencing factors. Powder Technol. 2019, 348 , 13–23. 10.1016/j.powtec.2019.03.016.
Iváncsy T. ; Kiss I. ; Berta I. Improved model for the analysis of back corona in pulse energised electrostatic precipitators. J. Electrost. 2009, 67 (2–3 ), 146–149. 10.1016/j.elstat.2009.01.057.
Heiredal M. L. ; Jensen A. D. ; Thøgersen J. R. ; Frandsen F. J. ; Friemann J. U. Pilot-scale investigation and CFD modeling of particle deposition in low-dust monolithic SCR DeNOx catalysts. AIChE J. 2013, 59 (6 ), 1919–1933. 10.1002/aic.13990.
White H. J. Particle Charging in Electrostatic Precipitation. Trans. Am. Inst. Electr. Eng. 1951, 70 (2 ), 1186–1191. 10.1109/T-AIEE.1951.5060545.
Luo K. ; Li Y. ; Zheng C. ; Gao X. ; Fan J. Numerical simulation of temperature effect on particles behavior via electrostatic precipitators. Applied Thermal Engineering 2015, 88 , 127–139. 10.1016/j.applthermaleng.2014.11.078.
Lupion M. ; Rodriguez-Galan M. ; Alonso-Fariñas B. ; Gutierrez Ortiz F. J. Investigation into the parameters of influence on dust cake porosity in hot gas filtration. Powder Technol. 2014, 264 , 592–598. 10.1016/j.powtec.2014.05.042.
Wang X. ; Ni M. ; Xiao G. ; Zhang J. ; Gao X. ; Cen K. An analytical method for DC negative corona discharge in a wire-cylinder device at high temperatures. J. Electrost. 2014, 72 (4 ), 270–284. 10.1016/j.elstat.2014.05.001.
Zhou W. ; Jiang R. ; Sun Y. ; Chen B. ; Liu B. Study on multi-physical field characteristics of electrostatic precipitator with different collecting electrodes. Powder Technol. 2021, 381 , 412–420. 10.1016/j.powtec.2020.12.028.
White H. J. ; Authors A. Particle Charging in Electrostatic Precipitation. Transactions of the American Institute of Electrical Engineers 1951, 70 (2 ), 1186–1191. 10.1109/T-AIEE.1951.5060545.
Shi Y. ; Fang M. ; Wang Q. ; Yan K. ; Cen J. ; Luo Z. Enhanced high-temperature particle capture through an electrostatic precipitator with assistant electrodes. Sep. Purif. Technol. 2023, 324 , 124550 10.1016/j.seppur.2023.124550.
