Enhanced Fine Particle Collection by the Application of SMPS Energization
Over the past decade or so the health problems associated with the inhalation of submicron particles from industrial processes has taken prominence and has lead to the stricter legislation of emissions such as the US PM2.5 approach. Generally most forms of control equipment readily handle and collect particles greater than 1 micron diameter, however, those less than 1 micron diameter are very much more difficult to collect. In the case of electrostatic precipitation, which involves both particle charging and migration under the influence of an electric field, the larger particles, generally greater than 1 micron are charged by collision with the ions and electrons present in the inter electrode area. It will be shown that the charge on these particles is proportional to the radius squared and its migration velocity proportional to the voltage squared, both reducing with particle size. The very small particles however, are charged by a diffusion processes and migrate under the influence of Brownian Motion which increases as the particle size decreases. The result of this is that a typical particle size/efficiency curve indicates a significant penetration window in the 0.8 to 0.2 micron diameter,which coincides with the change from collision to diffusion charging of the particles. Because of this penetration window, should an existing precipitator operating under optimum electrical conditions, not comply with fine particle emission requirements, the conventional enhancement scenario would be to increase the precipitators plate area, a very expensive solution, since the charging and precipitation operating conditions have been already optimised. It will be shown, however, that the replacement of the conventional mains energization system by an SMPS approach in an existing ESP will enhance the collection efficiency of particles in the penetration window as a result of the increase in both operating field voltages and currents. An application was applied to a 2 field ESP, dealing predominately with sub micron fume. This was initially assessed using PALCPETM (Proactive Approach to Low Cost Precipitator Enhancement), which indicated a significant reduction in the fine particle emissions was achievable by operation under SMPS Operation. An SMPS unit was subsequently fitted to the outlet field of this precipitator and the operating data will be examined in detail. With the outlet field under a mains rectification energization system the overall emission was -25 mg/Nm3, which after installation of the SMPS unit reduced to less than 15 mg/Nm3.
ESP fundamentals and applications Enhanced Collection of Sub-micron Sized Particles for Electrostatic Precipitators
Kenneth Parker Arne Thomas Haaland Frode Vik Arne Thomas Haaland
Ken Parker Consultant APC Applied Plasma Physics AS Norway
国际会议
11th International Conference on Electrostatic Precipitation(第11届国际电除尘学术会议)
杭州
英文
374-380
2008-10-15（万方平台首次上网日期，不代表论文的发表时间）