Abstract
ABSTRACT Electrostatic precipitation processes have been widely applied to remove particulate matter from flue gases in coal-fired power stations. A high negative voltage is usually applied to a discharge electrode so that the gases are ionized in such processes. When the suspended particles in flue gases enter the ionized space, they are electrically charged and deposited on collection plates to form the layer of particle packing. However, the dust layer generally exists during the precipitation of charged particles on the collection plate. The negative effect of precipitated dust layer on the collection plate causes the collection efficiency of electrostatic precipitator (ESP) to deteriorate seriously due to some critical factors, such as dust resistivity and thickness of accumulated dust. In this study, a simulation method by computational fluid dynamics method was applied to investigate the particle collection performance of the ESP system with and without a dust layer. Also, the detailed electric parameters and particle capture performance in the 2D wire-plate electrode configuration were simulated. The results show that the voltage-current characteristics and detailed distribution of electric field and ion charge density are completely different under various dust resistivity conditions. The effect of the dust layer is significant, which causes collection efficiency to decrease sharply with the increasing thickness (1–5 mm) of the dust layer. Furthermore, results indicate that when particles with higher resistivity enter the ESP, their migration velocity decreases sharply. In the case of 80 kV, when the dust resistivity is 1012 Ω·cm, the decline rate of particle migration velocity reaches 57.7%. Meanwhile, useful suggestions were provided to reduce the effects of dust layers by regulating particle properties and designing dust removal systems.
Highlights
An electrostatic precipitator (ESP) is the most commonly used device to remove dust particles from flue gas in many industrial areas, such as coal-fired power plants, steel mills, and construction material factories (Mizuno, 2002; Jaworek et al, 2018; Zheng et al, 2019b)
Dust particles are collected in an ESP, and a dust layer is formed on the dust collecting plate
The effect of the dust layer on particle migration in a low-temperature ESP was investigated in detail
Summary
An electrostatic precipitator (ESP) is the most commonly used device to remove dust particles from flue gas in many industrial areas, such as coal-fired power plants, steel mills, and construction material factories (Mizuno, 2002; Jaworek et al, 2018; Zheng et al, 2019b). The main chemical components of the particles are Si, Al, Fe, Ca, Mg, K, and Na. Traditional research results show that resistivity is a key factor in the efficient and stable operation of ESPs (Barranco et al, 2007; Aleksin et al, 2017). If resistivity is extremely high, the migration velocity of particles decreases remarkably, and back corona occurs under high resistivity These conditions cause a considerable drop in dust removal efficiency. In the actual operation process, especially in the stable operation of power supply, a quantitative study on the effect of the dust layer has not been published and resistivity on the operating characteristics and performance of the precipitator have not been reported
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