10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Exploring the Methods of Enhancing the Particle Charge in ESP
DAWEI DUAN, Chenghang Zheng, Qianyun Chang, Zhengda Yang, Yi Wang, Yifan Wang, Xiang Gao, Zhejiang University
Abstract Number: 760 Working Group: Control and Mitigation
Abstract Electrostatic precipitator (ESP) is a widely used particle control device for its high efficiency and wide adaptability. The overall mass based collection efficiencies for ESPs exceed 99%. However, results of field measurements have shown that there is a “penetration window” in the submicrometer size ranges, where the collection efficiency is as low as 70～80%.Hence, improving the collection efficiency on the particle of submicrometer size ranges is the key to decrease the emission concentration of ESP. The key to improve the collection efficiency of the particle of submicrometer size ranges is to increase its charge.
Many factors such as ion density, electrical field strength, particle properties, flue gas parameters and so on can affect the particle charge. The current researches mainly focused on the influence of ion density and electrical field strength on particle charging. Few researches have been done on the influence of particle parameters and temperature on the charge of particles. In this study, an experimental ESP was designed to explore the effects of particle properties (particle size, composition, etc.), flue gas parameters and water droplet humidification on particle charge. The temperature can be controlled from 298K to 383K and water droplet concentration can be controlled from 2.0 to 8.8g/m3. Six kinds of fly ash with different dielectric constant were used as the experimental particle. An electrical low pressure impactor (ELPI+) was used to measure the fractional particle charge.
The results showed that the particle charge increased with the increasing temperature. The charge of particle with the diameter of 1.2μm was enhanced by 25% with the temperature improved from 300K to 363K. In addition, particle charge increased as the dielectric constant increased. Besides, when the particle had a water layer on its surface, the particle charge was much larger than without the water layer. The average charge of particles larger than 0.5 μm was increased by more than 35% with the water droplet concentration of 8.8g/m3.