Effect of AC Electric Field Frequency on Electrical Agglomeration of Aerosol Particles

Abstract

Growing concern regarding, global atmospheric pollution has led to increasing interest in reducing the emission of fly ash particles. Electrostatic precipitator is a flue gas particle collector commonly used in coal-fired power plants. Since ESP has relatively low efficiency for the collection of submicron-sized particles, electrostatic agglomeration has been proposed to enhance the collection efficiency. In this work, we investigated the characteristics of electrostatic agglomeration of fine aerosol particles which experience DC corona charging and AC applied particle motion control. The particles (primary particles) were produced from NaCl resolved solution using an atomizer. By controlling the concentration of the NaCl solution, it was possible to produce different sized particles. The primary particles collided with each other and then became pearl-chain shape agglomerates. This study was initiated for enhancing agglomeration among unipolar charged particles by using the alternating electric field to increase the relative motion between the particles. Application of AC voltage promotes agglomeration in addition to that caused by Brownian motion. A particle oscillating amplitude increases as the particle size increases from submicron to micron. By controlling the concentration of the NaCl solution, it was possible to use the initially different sized particles. The particle size was sampled and observed with SEM photograph. The results showed that the number of agglomerated particles mainly depend on the DC field intensity and the AC field frequency.