Correlations between Particle Collection Behaviors and Electrohydrodynamics Flow Characteristics in Electrostatic Precipitators

Zhengda Yang,Ye Jiang,Chenghang Zheng,Yang Yang,Hanqing Li,Xiang Gao,Riyi Lin,Deshan Sun,Qingyi Li

doi:10.4209/aaqr.2020.07.0475

Abstract

Electrostatic precipitators (ESPs) are widely used to eliminate particulate matter emissions from industrial sources. However, the complex electrohydrodynamics (EHD) flow in ESPs can cause controversial conclusions on particle collection. This paper established an ESP model with an additional source term added to the equation of gas momentum conservation. Correlations between particle motion behaviors and EHD flow characteristics were investigated regarding various discharge voltage, particle size, and electrode position. Results show that the EHD flow presented a back-and-forth distribution between the electrode and plate. The peak value of vy can be as high as 0.15 m s–1. The EHD flow can cause four possible types of particle motion status. The dominant factor for particle motion switched between the electric force and drag force along with the particle motion trajectory. There existed an escaping window at the ESP inlet. Particles released from this window penetrated through the ESP rather than be collected. Modifying the ESP geometry and increasing voltage can narrow the escaping window. When the ESP channel width was narrowed from 0.06 to 0.05 m, the maximum NEHD could increase by 73.4% from 0.94 to 1.63. Consequently, the collection efficiency was significantly improved. The collection efficiency can even amount to 100% for particles sized 2.5 µm.

Highlights

The elimination of air pollutants from power, steel, chemical, and other industries has been a universal requirement to improve the air quality (Chen et al, 2014; Chu et al, 2020; Lin et al, 2020)
EHD Flow Characteristics The ionic wind acts as an external disturbance to the primary gas flow, affecting the Electrostatic precipitators (ESPs) channel's overall gas flow pattern
This work focuses on determining the correlations between particle motion behaviors and the complex EHD flow characteristics in the ESP

Summary

Introduction

The elimination of air pollutants from power, steel, chemical, and other industries has been a universal requirement to improve the air quality (Chen et al, 2014; Chu et al, 2020; Lin et al, 2020). The primary principles are understood, fine particles' collection still faces challenges when going through complicated processes, including electrostatics, fluid dynamics, particle charging, and dynamics (Lin et al, 2012; Yang et al, 2020; Yang et al, 2021). The electrohydrodynamics (EHD, called electric wind or ionic wind) is one of the most crucial phenomena in ESPs generated from the momentum transfer between charged ions or particles and the neutral gas molecule (Farnoosh et al, 2011). It reflects the interaction between the primary flow and the secondary flow. Krupa et al implemented the PIV to study the velocity field of the EHD flow during the back corona discharge and revealed that the EHD flow started from the crater in the ash layer (Krupa et al, 2019)

Methods

Results

Conclusion