Research on electrostatic shielding characteristics of electrostatic precipitator

ABSTRACT

Air pollution control is a worldwide problem of common concern to all mankind. Electrostatic precipitator (ESP) plays an important role in the purification of flue gas and dust. At present, in a multi-electrode ESP, the middle discharge electrode is often inhibited by the outer discharge electrode, commonly known as electrostatic shielding, which seriously affects the electric field distribution and dust removal effect of ESP. In order to explore this characteristic, this research established a mathematical model of ESP and simulated the electrostatic shielding phenomenon of wire-plate ESP, which quantified the influence of various factors on the degree of electrostatic shielding and analyzed the potential impact of electrostatic shielding on particle charging and dust removal efficiency. The results of the study show that the wire-to-plate distance has the greatest impact on electrostatic shielding, followed by the discharge electrode radius, voltage, and the wire-to-wire distance. When the degree of electrostatic shielding increases, the dust removal efficiency of ESP decreases. In addition, increasing the number of discharge electrodes to increase the dust removal efficiency of ESP is only feasible within a certain range. When the number of discharge electrodes exceeds a certain threshold, the dust removal efficiency of ESP decreases due to the effect of electrostatic shielding. The results of the research provide guidance for the determination of the geometric parameters of ESP and can make theoretical predictions for the occurrence of electrostatic shielding, thereby effectively avoiding the occurrence of electrostatic shielding.

Implications: Electrostatic precipitator plays an important role in the purification of flue gas and dust. Electrostatic shielding seriously affects the electric field distribution and dust removal effect of ESP. The research quantified the influence of various factors on the degree of electrostatic shielding and analyzed the potential impact of electrostatic shielding on particle charging and dust removal efficiency. It is expected that through the research, some guidance will be provided for the determination of the geometric parameters of ESP and can make theoretical predictions for the occurrence of electrostatic shielding, thereby effectively avoiding the occurrence of electrostatic shielding.

Nomenclature

$E$	=	Electric field intensity [V/m]
$\rho$	=	Space charge density [C/m3]
${\epsilon }_0$	=	Vacuum dielectric constant [F/m]
$J$	=	Current density [A/m2]
$Z_{\mathrm{i}\mathrm{o}\mathrm{n}}$	=	Ion mobility [m2/ (V·s)]
$D$	=	Diffusion coefficient [m2/s]
$E_0$	=	Corona initiation electric field intensity [V/m]
$r_c$	=	Discharge electrode radius [cm]
$I$	=	Identity matrix
$u_f$	=	Airflow velocity [m/s]
$p$	=	Pressure [Pa]
${\rho }_f$	=	Airflow density [kg/m3]
$k$	=	Turbulent kinetic energy [m2/s2]
$\rho (-\mathrm{\nabla }\phi )$	=	Volume force
$\omega$	=	Specific dissipation rate [s−1]
$\mu$	=	Viscosity coefficient [Pa·s]
$Q_s$	=	Particle saturation charge [C]
$Q_p$	=	The amount of charge a particle reaches somewhere [C]
${\epsilon }_r$	=	Relative permittivity [F/m]
$k_B$	=	Boltzmann constant [J/K]
$d_{par}$	=	Particle diameter [μm]
$t_q$	=	Time constant of particle charging
$T$	=	Temperature [K]
${\rho }_{ion}$	=	Space charge density per unit area [C/m3]

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Available on request (https://doi.org/ 10.1080/10962247.2021.2017374).

Additional information

Funding

This work was supported by the [National Key Research and Development Plan] under Grant [No. 2017YFB0603202] and [Fundamental Research Funds for the Central Universities] under Grant [No. FRF-GF-19-009B].

Notes on contributors

Bing Chen

Bing Chen received Ph.D. degree in Beijing Institute of Technology (BIT) in 2005, Beijing, People’s Republic of China. Now he works in University of Science and Technology Beijing (USTB) as an associate professor and supervisor of master graduate students, he is also the Associate Chair of the Department of Mechanical Equipment and Control Engineering. His current research interests include Air pollutant control, electrostatic precipitation technology and simulation.

Shiqing Li

Shiqing Li is a student of Beijing University of Science and Technology.

Yongheng Guo

Yongheng Guo is a student of Beijing University of Science and Technology.

Hongjiao Li

Hongjiao Li is a student of Beijing University of Science and Technology.

Wenning Zhou

Wenning Zhou is a teacher at Beijing University of Science and Technology.

Baiqian Liu

Baiqian Liu is a teacher at Beijing University of Science and Technology.