On trimodal particle size distributions in fly ash from pulverized-coal combustion

This article presents the differential mass size distributions of coal combustion particulate matter (PM) determined with the Berner low-pressure impactor (BLPI, Hauke Model 25-4/0.015) and a newer generation of low pressure impactor, the Dekati lowpressure impactor (DLPI, Dekati Ltd Model 6281). The collection characteristics of the BLPI and DLPI are compared and cutoff diameters are calculated. Samples were collected in the postcombustion zone of a 19 kW vertical downflow combustor from two coal types. Both BLPI and DLPI represent a tri-modal distribution and give statistically similar characterizations of the coal ash particle size distribution. Distributions generated from DLPI data have higher fractions of submicron particles compared to those generated from BLPI data. The DLPI's two additional stages may provide greater resolution in the submicron region than the BLPI.

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“…This tri-modal PSD is consistent with previous research on PSD of coal combustion PM (Seames 2003;Linak et al 2002).…”

Section: Psd Comparison Of Blpi and Dlpi Sample Setssupporting

confidence: 92%

“…Many experimental studies have used these impactors (Hillamo and Kauppinen 1991;Howell et al 1998;Seames et al 2002;Hillamo et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Coal Ash Particle Size Distributions from Berner and Dekati Low Pressure Impactors

Wang

Seames

Gadgil

et al. 2007

Aerosol Science and Technology

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“…Additional fuel analyses are presented elsewhere. 18,20 Particle Sampling and Characterization PM measurements were performed using several methods to examine particle size distributions (PSDs), elemental compositions, and speciation. These include PSD determinations based on electrical mobility, time-of-flight, inertial impaction, and light scattering techniques, and chemical analysis based on X-ray fluorescence (XRF) spectroscopy and X-ray absorption fine structure (XAFS) spectroscopy.…”

Section: Particulate Sources and Characteristicsmentioning

confidence: 99%

“…Details regarding these techniques and the results of these measurements can be found elsewhere. 18,20,21 PM for toxicological analyses was collected using two techniques. Relatively large quantities of coarse (Ͼ2.5 m) and fine (Ͻ2.5 m) particles were collected using a large-dilution sampler capable of sampling 0.28 m 3 /min of flue gas.…”

Section: Particulate Sources and Characteristicsmentioning

confidence: 99%

Differential Pulmonary Inflammation and In Vitro Cytotoxicity of Size-Fractionated Fly Ash Particles from Pulverized Coal Combustion

Gilmour

O'Connor

Dick

et al. 2004

Journal of the Air & Waste Management Association

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Exposure to airborne particulate matter (PM) has been associated with adverse health effects in humans. Pulmonary inflammatory responses were examined in CD1 mice after intratracheal instillation of 25 or 100 g of ultrafine (Ͻ0.2 m), fine (Ͻ2.5 m), and coarse (Ͼ2.5 m) coal fly ash from a combusted Montana subbituminous coal, and of fine and coarse fractions from a combusted western Kentucky bituminous coal. After 18 hr, the lungs were lavaged and the bronchoalveolar fluid was assessed for cellular influx, biochemical markers, and pro-inflammatory cytokines. The responses were compared with saline and endotoxin as negative and positive controls, respectively. On an equal mass basis, the ultrafine particles from combusted Montana coal induced a higher degree of neutrophil inflammation and cytokine levels than did the fine or coarse PM. The western Kentucky fine PM caused a moderate degree of inflammation and protein levels in bronchoalveolar fluid that were higher than the Montana fine PM. Coarse PM did not produce any significant effects. In vitro experiments with rat alveolar macrophages showed that of the particles tested, only the Montana ultrafine displayed significant cytotoxicity. It is concluded that fly ash toxicity is inversely related with particle size and is associated with increased sulfur and trace element content.

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“…The PSDs agreed well in the region where SMPS and APS overlap. The combined PSDs covered the ultrafine mode, fine mode and coarse modes, from 14.3 nm up to 20 µm (Baxter 1992, Smith et al 1979, Linak et al 2000, Linak et al 2002. The ultrafine mode ranges from 14.1 nm to 100 nm; the fine ranges from 100 nm to 900 nm; and the coarse mode comprises particles greater than 900 nm.…”

Section: Diffusion Control and Kinetics Controlmentioning

confidence: 99%

Oxy-coal Combustion Studies

Wendt

Eddings

Lighty

et al. 2012

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The objective of this project is to move toward the development of a predictive capability with quantified uncertainty bounds for pilot-scale, single-burner, oxy-coal operation. This validation research brings together multi-scale experimental measurements and computer simulations. The combination of simulation development and validation experiments is designed to lead to predictive tools for the performance of existing air fired pulverized coal boilers that have been retrofitted to various oxy-firing configurations. In addition, this report also describes novel research results related to oxy-combustion in circulating fluidized beds. For pulverized coal combustion configurations, particular attention is focused on the effect of oxy-firing on ignition and coal-flame stability, and on the subsequent partitioning mechanisms of the ash aerosol. To these ends, the project has focused on the following:• The development of reliable Large Eddy Simulations (LES) of oxy-coal flames using the Direct Quadrature Method of Moments (DQMOM) (Subtask 3.1). The simulations were validated for both non-reacting particle-laden jets and oxy-coal flames.• The modifications of an existing oxy-coal combustor to allow operation with high levels of input oxygen to enable in-situ laser diagnostic measurements as well as the development of strategies for directed oxygen injection (Subtask 3.2). Flame stability was quantified for various burner configurations. One configuration that was explored was to inject all the oxygen as a pure gas within an annular oxygen lance, with burner aerodynamics controlling the subsequent mixing.• The development of Particle Image Velocimetry (PIV) for identification of velocity fields in turbulent oxy-coal flames in order to provide high-fidelity data for the validation of oxy-coal simulation models (Subtask 3.3). Initial efforts utilized a laboratory diffusion flame, first using gas-fuel and later a pulverized-coal flame to ensure the methodology was properly implemented and that all necessary data and image-processing techniques were fully developed. Success at this stage of development led to application of the diagnostics in a large-scale oxy-fuel combustor (OFC).• The impact of oxy-coal-fired vs. air-fired environments on SO x (SO 2 , SO 3 ) emissions during coal combustion in a pilot-scale circulating fluidized-bed (CFB) (Subtask 3.4). Profiles of species concentration and temperature were obtained for both conditions, and profiles of temperature over a wide range of O 2 concentration were studied for oxy-firing conditions. The effect of limestone addition on SO 2 and SO 3 emissions were also examined for both air-and oxy-firing conditions.• The investigation of O 2 /CO 2 and O 2 /N 2 environments on SO 2 emissions during coal combustion in a bench-scale single-particle fluidized-bed reactor (Subtask 3.5). Moreover, the sulfation mechanisms of limestone in O 2 /CO 2 and O 2 /N 2 environments were studied, and a generalized gassolid and diffusion-reaction single-particle model was developed to s...

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On trimodal particle size distributions in fly ash from pulverized-coal combustion

Cited by 144 publications

References 19 publications

Comparison of Coal Ash Particle Size Distributions from Berner and Dekati Low Pressure Impactors

Comparison of Coal Ash Particle Size Distributions from Berner and Dekati Low Pressure Impactors

Differential Pulmonary Inflammation and In Vitro Cytotoxicity of Size-Fractionated Fly Ash Particles from Pulverized Coal Combustion

Oxy-coal Combustion Studies

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