Vaporization and condensation of mineral matter during pulverized coal combustion

Neville, M.A.; Quann, Richard J.; Haynes, Brian S.; Sarofim, Adel F.

doi:10.1016/s0082-0784(81)80130-0

Cited by 125 publications

(122 citation statements)

References 4 publications

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“…T h s system has been used extensively to study the fate of mineral matter in the coal. Some of the major findings reported by this group (Sarofim et al, 1977;Mims et al, 1980;Neville et al, 1981;Haynes et al, 1982;Neville and Sarofim, 1982; are these:…”

Section: Drop-tube Studiesmentioning

confidence: 80%

Effect of Coal Type and Residence Time on the Submicron Aerosol Distribution from Pulverized Coal Combustion

Linak

Peterson

1984

Aerosol Science and Technology

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Three types of pulverized coal were burned in a laboratory furnace under various combustion configurations. Pulverized samples of Utah bituminous, Beulah (North Dakota) lignite, and Texas lignite coals were burned at a rate of 2.5 kg/hr in a laboratory furnace. Aerosol sue distributions were measured at various positions within the convection section, and temperature and gas compositions were measured throughout. The evolution of the submicron particle size distribution within the convection section for the three coals was similar, although the location of the initial particle mode at the convection section inlet varied with coal type. While staged combustion of Utah bituminous coal had a variable effect on the volume of submicron aerosol produced, staged combustion of the lignites caused a definite increase in the submicron aerosol volume. Vapor enhancement due to a localized reducing atmosphere, yhich would effect coals of higher ash volatility, is thought to explain this behavior.

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Section: Drop-tube Studiesmentioning

confidence: 80%

Effect of Coal Type and Residence Time on the Submicron Aerosol Distribution from Pulverized Coal Combustion

Linak

Peterson

1984

Aerosol Science and Technology

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“…The evolution of particles following these approximate equations has been demonstrated in small-scale studies of aerosols formed from combustion systems for fly ash from coal 22,54,55 and soot particles 30,56,57 and waste combustors. 58,59 As shown by eqs 8 and 9, the number and size of particles can be determined for n 0 kt >> 1 if the amount of material in the form of the aerosol is known.…”

Section: Particle (Soot) Inception By Chemical Reactionmentioning

confidence: 98%

“…[16][17][18][19][20] This is supported by simple treatments of nucleation and growth of particles in a boundary layer. [21][22][23] More detailed treatment of nucleation in the boundary layer of a growing particle is presented by Peshty et al, 24 who show that the correct treatment should allow for heat release due to condensation, which tends to suppress the nucleation rate locally.…”

Section: Nucleation Versus Surface Growthmentioning

confidence: 99%

Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health

Lighty

Veranth

Sarofim

2000

Journal of the Air & Waste Management Association

1,022

600

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Particulate matter (PM) emissions from stationary combustion sources burning coal, fuel oil, biomass, and waste, and PM from internal combustion (IC) engines burning gasoline and diesel, are a significant source of primary particles smaller than 2.5 µm (PM 2.5 ) in urban areas. Combustion-generated particles are generally smaller than geologically produced dust and have unique chemical composition and morphology. The fundamental processes affecting formation of combustion PM and the emission characteristics of important applications are reviewed. Particles containing transition metals, ultrafine particles, and soot are emphasized because these types of particles have been studied extensively, and their emissions are controlled by the fuel composition and the oxidant-temperature-mixing history from the flame to the stack. There is a need for better integration of the combustion, air pollution control, atmospheric chemistry, and inhalation health research communities. Epidemiology has demonstrated that susceptible individuals are being harmed by ambient PM. Particle surface area, number of ultrafine particles, bioavailable transition metals, polycyclic aromatic hydrocarbons (PAH), and other particle-bound organic compounds are suspected to be more important than particle mass in determining the effects of air pollution. Time-and size-resolved PM measurements are needed for testing mechanistic toxicological hypotheses, for characterizing the relationship between combustion operating conditions and transient emissions, and for source apportionment studies to develop air quality plans. Citations are provided to more specialized reviews, and the concluding comments make suggestions for further research.

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“…Under conditions of growth by coagulation where coalescence is not rate-limiting, such as the elevated temperatures of the ame zone, the primary particle diameter of coagulating combustion-derived aerosols will scale with the mass loading of inorganic vapor to the 2/5 power (Neville et al 1981). When coalescence becomes growth rate controlling, the mass concentration of aerosol can be expected to have a corresponding effect on the size of the fractal-like ag- gregate structures.…”

Section: Bench Scale Experiments Utilizing Controlled Composition Aermentioning

confidence: 99%

“…These reduced inorganic vapors oxidize, supersaturate, and subsequently condense both homogeneously and heterogeneously to form submicron particulate matter. At the high temperatures of a combustion ame, these particles grow by collision and rapid coalescence to form larger, generally spherical particles (Flagan 1979;Neville et al 1981). As post-combustion gas and particle temperatures decrease, however, coalescence rates become slow relative to interparticle collision rates.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Chemical Composition on the Fractal-Like Structure of Combustion-Generated Inorganic Aerosols

Liu¹,

Srinivasachar²,

Helble³

2000

Aerosol Science and Technology

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ABSTRACT. The morphology of submicron ame-generated inorganic aerosols is known to be fractal-like with reported fractal exponents ranging from 1.1 -2.5 for different materials. This wide range represents a correspondingly broad variation in structure and suggests that chemical composition might affect the nal structure of ame-generated materials, a prospect of considerable importance in studies of submicron particulate penetration through electrostatic precipitators. To investigate this, the morphology of ame-generated submicron aerosols was studied by characterizing both y ash generated in a pilot scale coal combustor and controlled composition inorganic aerosols generated in a bench scale at ame burner. Fly ash generated during combustion of 2 bituminous coals at 2 different ame temperatures was found to be fractal-like with fractal exponents of 1.9 -2 and fractal prefactors of 1.1 -1.5. In addition, y ash samples collected at the inlet and outlet of an attached pilot scale electrostatic precipitator yielded no difference in particle morphology, indicating a lack of structure-dependent penetration. Flame-generated silica, magnesia, sodium-doped silica, and magnesium-doped silica produced under identical conditions in an invariant premixed ame were also fractal-like in structure with fractal exponents of 1.7 -1.8 and fractal prefactors of 1.6 -1.8. No dependence of these structural parameters on chemical composition, ame residence time, or particle number density was observed over the ranges considered. Changing chemical composition did, however, lead to order of magnitude changes in primary particle diameter without any corresponding change in aggregate structure. Findings from both systems are consistent with a growth process governed in the late stages by cluster-cluster aggregation and indicate that for ame synthesized materials produced in the overall decreasing temperature gradient characteristic of coal combustors and industrial ame reactors, the aerosol aggregate structure will not be affected by changes in chemical composition under conditions of coalescence-limited growth.¤ Corresponding author. 460 B. B. Liu et al.

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Vaporization and condensation of mineral matter during pulverized coal combustion

Cited by 125 publications

References 4 publications

Effect of Coal Type and Residence Time on the Submicron Aerosol Distribution from Pulverized Coal Combustion

Effect of Coal Type and Residence Time on the Submicron Aerosol Distribution from Pulverized Coal Combustion

Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health

The Effect of Chemical Composition on the Fractal-Like Structure of Combustion-Generated Inorganic Aerosols

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