Electrostatic precipitator (ESP) is widely used for dust removal from flue gas in industry. In the electrostatic precipitation, the electrohydrodynamic secondary flow (EHD) produced by corona ionization has an important influence on the characteristics of particle transport and the collection efficiency of ESP. In this work, a comprehensive ESP model with interaction of multiple physical fields is established to study the EHD effect in ESP. The numerical results show that the EHD generally can increase the streamwise velocity of airflow near the collection plate, which makes the removal performance of ESP worsen. Meanwhile, the EHD has a significant effect on the particle deposition pattern, especially at lower flue gas velocity. When the needle tip of discharge electrode points to the collection plate, the EHD can promote the circulation of airflow near the corona wire, increase the probability of particle charging, and then improve the collection efficiency of ESP.
Owing to the oversimplification of the evaporation model, existing numerical analysis cannot accurately characterize the evaporation characteristics, which has limited its significance for engineering. Therefore, by user-defined programming, a droplet evaporation model in line with the properties of desulfurization wastewater was implemented in numerical simulation. The effects of guiding measures, nozzle arrangement, nozzle layer, flue gas temperature, moisture and droplet diameter on the droplet evaporation in a bypass flue were explored. The numerical results show that the fluctuation of evaporativity due to moisture can be neglected. The uniformity of the flow field with guiding measures is good and the phenomenon of droplets impinging on the wall surface can be prevented. The droplet collision probability without guiding measures may be nearly 60 times higher than that with guiding measures. A reasonable nozzle arrangement increases the droplet evaporation rate and reduces the probability of droplets colliding with the wall surface. An increased number of nozzle layers enhances the droplet evaporation rate and the average temperature in the flue; by estimation, the average temperature in the flue with three nozzle layers is 10.7 K higher than that for two nozzle layers, and 15.8 K higher than that for one nozzle layer. In the condition of higher temperature and smaller diameter, droplets evaporate more rapidly. These research results can provide a reliable reference for engineering practice.
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