Field Measurements on the Emission and Removal of PM_2.5 from Coal-Fired Power Stations: 3. Direct Comparison on the PM Removal Efficiency of Electrostatic Precipitators and Fabric Filters

Abstract

This contribution reports direct comparison of the particulate matter (PM) removal efficiencies of electrostatic precipitators (ESPs) and fabric filters (FFs) installed in two 300 MW coal-fired power station units that are equipped with identical boilers and DeNO x units. Field PM measurements were carried out at the horizontal ducts at the inlets of the DeNO x units, as well as the inlets and outlets of the two dust collectors when the two boilers burned the same coal under identical combustion conditions. The PM and total fly ash were collected via a low-pressure impactor (LPI) and/or a smoke analyzer. The collected samples were then subjected to analysis for chemical composition and morphology using an X-ray fluorescence (XRF) probe and a field emission scanning microscope with an energy-dispersive X-ray analyzer (FESEM-EDX). The results show that both the ESPs and the FFs can effectively capture PM, with a PM2.5 collection efficiency of 99.63% and 99.95%, respectively. For the PM with similar properties, the collection efficiencies in the FFs are only marginally higher than those in the ESPs. The most notable discrepancies between the fractional PM removal efficiencies of ESPs and FFs are observed for PM in the size range 0.3–2 μm. The PM removal performance of both the ESPs and the FFs is related to particle size. At 0.3–2 μm, the performance of the ESPs is more sensitive to particle size than the FFs. The PM collection efficiency of the FFs is inversely related to particle size, and the capture of PM around 0.4 μm is slightly weak, most likely due to the transition of capture mechanisms from impaction to Brownian diffusion.

Influences of In-Furnace Kaolin Addition on the Formation and Emission Characteristics of PM2.5 in a 1000 MW Coal-Fired Power Station

“…Samples of the total fly ash in the flue gas into the ESPs were also collected via a commercial dust collector (Laoying 3012H smoke/gas analyzer), following the procedures described elsewhere. 22 Flue gas was extracted out of the flue duct via a probe, and the entrained ash particles were collected in the glass fiber filter cartridge embedded in it. The chemical composition and specific resistivity of the ash samples were determined via the XRF and a dust specific resistivity analyzer (DR-3, North China Electric Power University).…”

“…PM samplings were performed at the inlets and outlets of the ESPs (see Figure ) with two DLPI sampling systems, following the procedures described elsewhere. − Briefly, the DLPI sampling system consists of a cyclone (SAC-10, Dekati), a Dekati low pressure impactor (DLPI), a pressure gauge, and a vacuum pump. During the sampling, a stream of flue gas (10 L/min) was isokinetically extracted from the center of the flue duct via a probe and introduced into the cyclone to separate the particles with the aerodynamic diameters of >10 μm (PM >10 ).…”

“…Then, the flue gas passed through the DLPI in which the left particles ≤10 μm (PM 10 ) were separated and collected into 13 stages according to the particle size. All the sampling probe, cyclone, DLPI, and tubes connecting them were heated to 408 K, which is above the condensing temperature of SO 3 (∼383 K) in the flue gas, to avoid the condensation of acidic gases. ,, Each PM sampling at the inlets and outlets of the ESPs lasted for 1.5 and 90 min, respectively, to collect a suitable amount of PM sample. Moreover, PM samplings at the ESPs’ inlets and outlets at each experimental condition were repeated 4 times and 3 times, respectively, with the averages and error bars presented in the results.…”

“…Samples of the total fly ash in the flue gas into the ESPs were also collected via a commercial dust collector (Laoying 3012H smoke/gas analyzer), following the procedures described elsewhere . Flue gas was extracted out of the flue duct via a probe, and the entrained ash particles were collected in the glass fiber filter cartridge embedded in it.…”

Unexpectedly Increased Particle Emissions from the Steel Industry Determined by Wet/Semidry/Dry Flue Gas Desulfurization Technologies

“…Two-thirds of the TSP in the FGD inlets is composed of PM 2.5 (see Table ), while the TSP in the FGD outlets is affected by the desulfurization process, as shown in Figures and S3. The semidry CFB-FGD equipped with an FF had the highest dust removal efficiency, with average values of 0.54 ± 0.11 and 0.22 ± 0.06 mg/Nm 3 for TSP and PM 2.5 in the stack for S-5, respectively, while higher concentrations of PM >2.5 were observed in the S-4 stack after the semidry CFB-FGD process, possibly owing to the decrease in coarse particle removal efficiency caused by the long service life of the bags (see Table S1). Figures b and S3b present the mass concentrations of WSI components in PM 2.5 at the inlets and the outlets of the FGD systems of the five tested sinters.…”