10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Mist Removal Performance of a Novel Electrostatic Mist Eliminator Combined with a Flue Gas Desulfurization Process in a Coal-fired Power Plant
Hak-Joon Kim, Kim Jin-Seon, Kim Myungjoon, Bangwoo Han, Chang Gyu Woo, YONG-JIN KIM, Lee Sangrin, Korea Institute of Machinery and Materials
Abstract Number: 1667 Working Group: Control and Mitigation
Abstract As coal-fired power plants have become the main source of particulate matter in Korea recently, the need for improvement in environmental equipment is increasing. Particularly, the Korean government tried to reduce the emissions of fine dust by temporarily shutting down 8 coal-fired power plants from over 30 years old in June 2017. However, coal-fired power plants account for about 40 % of Korea’s total electricity production, making it difficult to shut them down or dispose of them immediately. Therefore, in this study, we intend to develop particle removal technology for coal-fired power plants. In general, the flue gas processing systems of the coal-fired power plant are composed of a selective catalytic reduction (SCR), an electrostatic precipitator (ESP), and a wet flue gas desulfurization (FGD). A mist eliminator (ME), a chevron type demister, is installed at the downstream of the FGD, removes particles and mists generated in the FGD. However, the existing ME has low particle removal efficiency because of its principle of particle removal of the inertial impaction. Consequently, in this study, a new type of an electrostatic mist eliminator (EME) was developed and evaluated as an alternative to the ME. Because the space at the downstream of FGD is limited, the EME was designed for a single-stage electrostatic precipitator with parallel charging and collecting plates whose geometry is usually used for two stage ESPs for indoor air quality. High voltage metallic and grounded plates were placed alternately. A lab scale prototype of the EME and ME were investigated to compare particle collection efficiency and pressure drop of the systems. Limestone (CaCO3) aqueous solution used in a FGD was aerosolized by using a twin-fluid nozzle to generate particles, and negative voltage of 10 to 14 kV was applied to high voltage plate of the EME. An optical particle counter and isokinetic particle sampler based on EPA Method 5 were used to measure the changes in particle mass concentrations at the upstream and downstream of the ME and EME. Each experiment was repeated two to three times. When the face velocity of the systems increased from 2 to 5 m/s, the efficiency of the ME against TSP (Total suspended particle) and PM 2.5 increased from 20.0 to 33.9%, and 9.0 to 20.2%, respectively, while the efficiency of the novel EME against TSP and PM 2.5 decreased from 89.1 to 65.0% and 82.3 to 55.6%, respectively, when -14 kV was applied. On the other hands, pressure drop of the ME and EME was varied from 44 to 241 Pa, and 5 to 29 Pa, respectively. TSP removal efficiency measured based on EPA Method 5 was 83.1 and 19.4% for the EME and ME, respectively, when face velocity was 4 m/s. These results indicated that the novel EME has high particle collection efficiency up to approximate 90% compared to the general ME and extremely low pressure drop by approximate 1/10. Therefore, we expect the EME can contribute to reduce the emissions of fine particles from coal-fired power plants.
This work was supported by the Industrial Technology Innovation Program (NE5750) of the Korea Institute of Energy Technology Evaluation and Planning granted by financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea, and also by the Basic Research Fund (NK212E) of the Korea Institute of Machinery & Materials.