High-efficiency wet electrocyclone for removing nanoparticle and microparticle

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 Cheina, Fang-Tang Changa aJG Environmental Technology Co., Ltd, No.8, Gaoping Sec., Zhongfeng Rd., Longtan Township, Taoyuan County 325, Taiwan 2012/11/20

2. Introduction • ESPs: Advantages: High efficiency for particles smaller than 10 μm. Disadvantages: High capital and operation and maintenance costs. (Shrimptonand 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.

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.

4. Experimental Method • Test particles: Oleic acid, Al2O3, soot. • Oleic acid: Generated by Atomizer Model 3076 PSI, resistivity is 8.0~16×108Ω-cm. • Al2O3: Generated by Jet-O-Mizer (Fluid Energy Model 000), resistivity is 10×1012~14 Ω-cm。 • Soot: Generated by diffusion flame burner (Kim et al. 2009), resistivity is 3.5×10−3Ω-cm.

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

7. Results and discussion • Presure drop andI-V curve Kozlovet al. (2006); Adamiakand Atten (2004)

8. Air flow rate: 1000 L/min • Particle collectoin efficiency: Oleic acid, Al2O3, soot

9. Air flow rate: 2500 L/min • Particle collectoin efficiency: Oleic acid, Al2O3, soot

10. Air flow rate: 4500 L/min • Particle collectoin efficiency: Oleic acid, Al2O3, soot

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 • Al2O3 loading quantity: 180 g/hr/m2(0.37g/m3)

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

14. Field test

15. Conclusions • 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). Al2O3 (0.5~20 mm): 75~99%(4500 L/min), 87~99.9%(1000 L/min). • The applied voltage: 12.5-21 kV, corona current: 3.7-7.8 mA. • Collection efficiencies increase with increasing discharge discs. • Dry electrocyclone loading test: Loading time: 360 min. Thickness of dust cake: 0.5 cm. • Wet electrocyclones can be used to solve the problems occur in the traditional dry electrocyclones.

16. Thanks for your attention!