1. High-efficiency wet electrocyclone for removing nanoparticle and microparticle National Chiao Tung University Guan-Yu Lin, Le-Thi Cuc, Chuen-Jinn Tsai *, Wei Lu, Hung-Min Chein a, Fang- Tang Chang a a JG Environmental Technology Co., Ltd, No.8, Gaoping Sec., Zhongfeng Rd., Longtan Township, Taoyuan County 325, Taiwan 2012/11/20 1

2. Introduction  ESPs: Advantages: High efficiency for particles smaller than 10 μm. Disadvantages: High capital and operation and maintenance costs. (Shrimpton and Crane 2001; USEPA 2003a). Decrease in collection efficiency due to the accumulation of particles on collection electrode surfaces, back corona, and particle re-entrainment.  Cyclones: Advantages: Simple and cost efficient to construct. but have Disadvantages: Low collection efficiency for fine particles (USEPA 2003b).  Electrocyclones: Combination of ESPs and cyclones. 2

3. Objectives To design and develop a high efficiency wet electrocyclone.  Collection efficiency experiment for particles with different resistivity.  Optimum operation conditions: I-V curve, pressure drop, the quantity of water mist, flow rate of scrubbing water.  Loading test.  Field test. 3

4. Experimental Method  Test particles: Oleic acid, Al 2 O 3, soot.  Oleic acid: Generated by Atomizer Model 3076 PSI, resistivity is 8.0~16×10 8 Ω-cm.  Al 2 O 3 : Generated by Jet-O-Mizer (Fluid Energy Model 000), resistivity is 10×10 12~14 Ω-cm 。  Soot: Generated by diffusion flame burner (Kim et al. 2009), resistivity is 3.5×10 −3 Ω-cm. 4

5. 5  Inlet air flow rate: 1000(residence time=1.28 sec)~4500 (residentce time=0.28 sec)L/min 。  Applied voltage: 21 kV 。  Nozzle: mist diameter: 50  m ， water flow rate: 0.1 L/min 。  4 scrubbing water flow: 22 L/min 。  Tips to collection electrode spacing: 4 cm 。

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7. Results and discussion  Presure drop and I-V curve 7 Kozlov et al. (2006); Adamiak and Atten (2004)

8.  Air flow rate: 1000 L/min  Particle collectoin efficiency: Oleic acid, Al 2 O 3, soot 8

9.  Air flow rate: 2500 L/min  Particle collectoin efficiency: Oleic acid, Al 2 O 3, soot 9

10.  Air flow rate: 4500 L/min  Particle collectoin efficiency: Oleic acid, Al 2 O 3, soot 10

11. 11 Particle collection for three test particles. Particle collection for oleic acid with different number of discharge discs.

12.  Dry electrocyclone loading test.  Loading time: 2 hr  Al 2 O 3 loading quantity: 180 g/hr/m 2 (0.37g/m 3 ) 12

13.  Wet electrocyclone loading test  Loading time: 2 hr  Scrubbing water flow rate: 22 L/min, mist flow rate: 0.1 L/min 13

14. Field test 14

15. Conclusions 1.Particle collectoin efficiency: Oleic acid (20~800 nm): 78~92% (4500 L/min), 97~99% (1000 L/min). Soot (20~800 nm): 92~99%(4500 L/min), 99~99.9%(1000 L/min). Al 2 O 3 (0.5~20 mm): 75~99%(4500 L/min), 87~99.9%(1000 L/min). 2.The applied voltage: 12.5-21 kV, corona current: 3.7-7.8 mA. 3.Collection efficiencies increase with increasing discharge discs. 4.Dry electrocyclone loading test: Loading time: 360 min. Thickness of dust cake: 0.5 cm. 5.Wet electrocyclones can be used to solve the problems occur in the traditional dry electrocyclones. 15

16. Thanks for your attention!