Implications of particulate properties on electrostatic precipitator and fabric filter performance

Field Measurements on the Emission and Removal of PM2.5 from Coal-Fired Power Stations: 3. Direct Comparison on the PM Removal Efficiency of Electrostatic Precipitators and Fabric Filters

“…PM with aerodynamic diameters of >2 μm and <0.3 μm could be sufficiently charged via field charging and diffusion charging, respectively, and thereby can be effectively removed in the ESP. , However, PM in the size range 0.3–2 μm is difficult to be charged, as it is in the transition zone of field charging and diffusion charging, which results in the lower PM removal efficiency. , Apart from the increased diffusion charging with decreasing particle size, the S content in the ultrafine PM (e.g., PM in the size range 0.16–0.27 μm) is considerably higher than that in the PM of larger sizes (see Figure b). This would improve the adhesion behavior between particles and thereby promote the capture process. ,, …”

“…Third, the PM removal efficiency of the FFs appears to be inversely related to particle size except for the PM with diameters of ∼0.4 μm, the collection efficiency of which is also a little lower. During the working of FFs, particles are mainly captured by the collected ash layer on the surface of FFs via a sieving mechanism. ,− Some tiny pores and holes exist on the deposited ash layer, and some fine PM would penetrate through them, which leads to the lower capture efficiency for the fine PM. , When the deposited ash layer on FFs is blown away, PM is captured predominantly via inertial impaction, interception, and Brownian diffusion. , Under this condition, fine PM is more difficult to be captured by impaction and interception than the larger PM, which also results in the lower removal efficiencies for the smaller PM in the FFs. , PM with diameters of ∼0.4 μm is slightly less effectively captured than the others (as shown in Figure ), which is supposed to result from the transition of the capture mechanism from impaction and interception to Brownian diffusion . Sulfur enriched in the ultrafine PM may also promote the capture process because sulfates coated on the surface of ultrafine PM modify the roughness and cohesivity, which improves the adhesive forces between particles and thereby facilitates the capture of these particles (PM less than 0.4 μm). , …”

“…Besides ESPs, FFs (also called baghouses) are another widely used dust collection technology, especially in the power stations burning low-sulfur coal. ,, In FFs, PM is separated through inertial impaction, interception, or diffusion based on its size. Other properties, such as surface cohesivity, particle shape, and roughness (morphology), also affect the performance of the FF. , The PM 2.5 collection efficiency of the FFs in coal-fired power stations is reported to be as high as 99.72% . A recent measurement on a fabric filter at an industrial pulverized coal boiler (10 t/h) showed that the FFs had a total PM 2.5 removal efficiency of 99.37%–99.91% while exhibiting a low removal efficiency for PM in the size range 0.1–1 μm and less than 0.029 μm .…”

“…8,32,33 Other properties, such as surface cohesivity, particle shape, and roughness (morphology), also affect the performance of the FF. 34,35 The PM 2.5 collection efficiency of the FFs in coal-fired power stations is reported to be as high as 99.72%. 36 A recent measurement on a fabric filter at an industrial pulverized coal boiler (10 t/h) showed that the FFs had a total PM 2.5 removal efficiency of 99.37%−99.91% while exhibiting a low removal efficiency for PM in the size range 0.1−1 μm and less than 0.029 μm.…”

Numerical investigation of spatially nonhomogeneous acoustic agglomeration using sectional algorithm

“…In recent years, particles of microns and submicrons diameter are gaining attention as being harmful to public health (Pope et al 2000). To effectively remove particles from the air, the particle removal technologies such as electrostatic precipitators, filters, cyclones, and scrubbers are often used (Lee and Liu 1981;Kim and Lee 1990;Bush and Snyder 1992). However, Riley et al (2002) reported that a major challenge of the current particle removal technologies is the poor efficiency for small particles such as PM2.5 (particulate matter with a diameter of less than 2.5 mm).…”