A Plug Flow Model for Chemical Reactions and Aerosol Nucleation and Growth in an Alkali-Containing Flue Gas

Christensen, K.; Livbjerg, Hans

doi:10.1080/02786820050195331

Cited by 52 publications

(50 citation statements)

References 27 publications

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“…Skrifvars (1998) and Livbjerg (1996, 2000) used thermodynamic equilibrium considerations to explain/ predict the observed final emissions (including for the latter works HCl (g) and SO 2 (g)) in different biomass combustion systems. In the particle formation model developed by Christensen et al (2000), gas reaction kinetics are also taken into account. Not much empirical data are available for the reactions considered here, apart from those inferred by this group to fit their own field measurements.…”

Section: Physicochemical Evolution Of the Particlesmentioning

confidence: 99%

Formation and Emission of Submicron Particles in Pulverized Olive Residue (Orujillo) Combustion

Jiménez

Ballester

2004

Aerosol Science and Technology

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The particle formation and emission in the combustion of pulverized olive residue (orujillo) is studied in this work. The fuel has been burned in controlled combustion conditions in an entrained flow reactor. A bimodal distribution with mode peaks at 155 nm and 110 µm is found for fly ashes. Coarse particles have been characterized by laser diffractometry and SEM, while fines have been analyzed by low-pressure impaction, DMA, SEM, and X-ray diffraction. Particles with Dp < 1 µm are composed of only K 2 SO 4 and KCl in the same mass proportion, and possibly K 3 PO 4 (less than 7% in mass). The use of a new particle sampling probe and a TEM allowed a detailed study of the formation of these particles when flue gases cool down. K 2 SO 4 is experimentally found to start nucleation over 900• C, while KCl is not observed at this temperature. Condensation of KCl on these nuclei is observed in a sample taken at 560• C. These "formation steps" are in good agreement with both theoretical calculations by other authors and a simple equilibrium schema shown here.

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Section: Physicochemical Evolution Of the Particlesmentioning

confidence: 99%

Formation and Emission of Submicron Particles in Pulverized Olive Residue (Orujillo) Combustion

Jiménez

Ballester

2004

Aerosol Science and Technology

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“…Z is the Zeldovich nonequilibrium factor and N e A (q ¤ ) is the concentration of clusters of the critical size. The expressions for these terms, valid for homomolecular nucleation, have been modi ed for the simultaneous nucleation of monomers and dimers by Christensen (1995) and Christensen and Livbjerg (2000), who also included a curvaturedependent surface tension in their derivation. If there is chemical equilibrium between monomer and dimer vapors, the equilibrium cluster distribution as a function of cluster size q 3 becomes…”

Section: Condensation Of Pure Chloride Vaporsmentioning

confidence: 99%

The Nucleation of Aerosols in Flue Gases with a High Content of Alkali - A Laboratory Study

Jensen¹,

Nielsen²,

Schultz-Møller³

et al. 2000

Aerosol Science and Technology

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ABSTRACT. The formation of particles during cooling of a synthetic ue gas with vapors of sodium and potassium species is studied in a laboratory tubular reactor with laminar ow. It is shown to agree well with a theoretical model for the process. The kinetics of homogeneous nucleation of the pure chloride vapors is described by the classical nucleation theory, adapted to include the participation of stable dimer as well as monomer vapor molecules. The Tolman equation is used to describe the curvature-dependence of the surface tension of small nuclei. The values of the Tolman parameter for NaCl and KCl are determined from the measurements. The homogeneous nucleation of the pure chlorides is suppressed by even relatively small concentrations of foreign seed particles and is therefore unlikely to contribute to the creation of new particles in real ue gases.The addition of SO 2 to the chloride vapor feed, in the presence of oxygen and water vapor, increases the number concentration of ef uent particles signi cantly and affects their composition to include sulphate in addition to chloride. The sulphate content is independent of the peak temperatures of the ue gas but increases with increasing content of oxygen and SO 2 . The study proves that the alkali sulphates are formed by the sulphation of vapor phase rather than solid, alkali chloride. The sulphate vapors are formed in high supersaturation and show a pronounced tendency towards homogeneous nucleation, which is identi ed as the likely source of the submicron particles formed in alkali rich ue gases.

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“…18,23−26 If the particle loading in the system is low, KCl may form an aerosol by homogeneous nucleation. 24,25,27 Potassium chloride has a number of adverse effects in combustion units. Once deposited on heat transfer surfaces, it may act to lower the melting temperature of the deposit, forming a sticky surface that promotes further deposition.…”

Section: ■ Introductionmentioning

confidence: 99%

Sulfation of Condensed Potassium Chloride by SO₂

Hansen¹,

Bartolomé

Wu³

et al. 2013

Energy Fuels

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The interaction between alkali chloride and sulfur oxides has important implications for deposition and corrosion in combustion of biomass. In the present study, the sulfation of particulate KCl (90−125 μm) by SO 2 was studied in a fixed bed reactor in the temperature range 673−1023 K and with reactant concentrations of 500−3000 ppm SO 2 , 1−20% O 2 , and 4−15% H 2 O. The degree of sulfation was monitored by measuring the formation of HCl. Analysis of the solid residue confirmed that the reaction proceeds according to a shrinking core model and showed the formation of an eutectic at higher temperatures. On the basis of the experimental results, a rate expression for the sulfation reaction was derived. The model compared well with literature data for sulfation of KCl and NaCl, and the results indicate that it may be applied at even higher SO 2 concentrations and temperatures than those of the present study. Simulations of sulfation of KCl particles with different size indicate that only for very small KCl particles, below 1 μm, a considerable in-flight sulfation is achievable at the short gas residence times typical of combustion systems.

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A Plug Flow Model for Chemical Reactions and Aerosol Nucleation and Growth in an Alkali-Containing Flue Gas

Cited by 52 publications

References 27 publications

Formation and Emission of Submicron Particles in Pulverized Olive Residue (Orujillo) Combustion

Formation and Emission of Submicron Particles in Pulverized Olive Residue (Orujillo) Combustion

The Nucleation of Aerosols in Flue Gases with a High Content of Alkali - A Laboratory Study

Sulfation of Condensed Potassium Chloride by SO₂

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A Plug Flow Model for Chemical Reactions and Aerosol Nucleation and Growth in an Alkali-Containing Flue Gas

Cited by 52 publications

References 27 publications

Formation and Emission of Submicron Particles in Pulverized Olive Residue (Orujillo) Combustion

Formation and Emission of Submicron Particles in Pulverized Olive Residue (Orujillo) Combustion

The Nucleation of Aerosols in Flue Gases with a High Content of Alkali - A Laboratory Study

Sulfation of Condensed Potassium Chloride by SO2

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Sulfation of Condensed Potassium Chloride by SO₂