Development of Radiative Heat Transfer Model for Pulverized Coal Combustion

Asotani, Toshimitsu; Yamashita, Toru; Tominaga, Hiroaki; Itaya, Yoshinori; Mori, Shigekatu

doi:10.1252/kakoronbunshu.34.344

Cited by 1 publication

(1 citation statement)

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“…On the other hand, little work has been done for coal char, although the carbon contents in char changes in the progress of the reactions. Asotani et al (2008aAsotani et al ( , 2008b reported that the ignition of pulverized coal combustion burners is dependent on radiative heat transfer, and accurate radiation parameters and appropriate modeling are required for the correct prediction of stable ame formation on the burners. It is noticed that coal char does not only consist of a macro-scale of non-homogeneous composite particles with ash and carbon-based material, but also a micro-scale of soot particles adheres around the macro-scale of char particles in the sample collected from industrial furnaces.…”

Section: Introductionmentioning

confidence: 99%

Radiation Properties of Coal Char Particle Cloud

Itaya

Kosaka

Kobayashi

2013

J. Chem. Eng. Japan

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This study is to evaluate the radiation properties of coal char and ash particles. Char in coal-ring and gasi cation processes exists in the form of heterogeneous composite particles consisting of nano-order ne particles made mainly of soot and micron-order particles of carbon and ash components. The radiation properties are discussed in terms of apparent extinction e ciency determined from spectra of transmissivity of a particle-liquid para n wax dispersion lm as an independent parameter of particle dispersion density. Extinction e ciency measured directly from the original char gives an unacceptably great magnitude. However, if the original char was classi ed into a narrow particle size distribution by pretreatment with a wet method, the extinction e ciency of each particle showed a reasonable magnitude and successfully deduced an extinction coe cient of the original char dispersion with a certain content from combining that of each particle accounting for the fraction. The e ect of carbon content in char particle excluding soot on extinction efciency could also be correlated empirically by a simple function using the properties of carbon-free ash burnt out and ash-free carbon treated by hydro uoric acid. Additionally, the value of apparent extinction e ciency measured from transmissivity of ash dispersion was compared with the properties estimated by applying the known refractive index into Mie's theory, and noted to be closer to rather absorption e ciency than the extinction e ciency analyzed theoretically, although scattering albedo was as large as over 0.9. This fact may result in that a strong forward scattering pointed out in a previous work was reasonable and the ash particle cloud can be assumed as an absorbing-emitting medium having the properties obtained here, ignoring the e ect of scattering at least.

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Section: Introductionmentioning

confidence: 99%