Conversion of coal tar to soot during coal pyrolysis in a post-flame environment

Ma, Jinliang; Fletcher, Thomas H.; Webb, Brent W.

doi:10.1016/s0082-0784(96)80161-5

Cited by 59 publications

(53 citation statements)

References 10 publications

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“…There is strong evidence that particulate carbon formed during the release of volatile matter comes primarily from tar, and not from the lighter gases and hydrocarbons [ Solomon et al , 1988]. For example, in pyrolysis experiments where no oxidation occurs, the sum of tar and “soot” concentrations remains constant [ Wornat et al , 1987; Ma et al , 1996]. Highly volatile bituminous forms the most tar, followed by moderately volatile bituminous, sub‐bituminous, lignite and anthracite in that order [ Mitra et al , 1987].…”

Section: Resultsmentioning

confidence: 99%

Primary particle emissions from residential coal burning: Optical properties and size distributions

et al. 2002

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[1] Particles generated by combustion of fossil fuels contribute to climate forcing by absorbing and scattering visible light. Residential combustion takes place in homes for heating or cooking purposes and is thought to contribute a large fraction of the global burden of anthropogenic primary particles. We present optical properties and size distributions of particulate matter emitted from three types of coal burned in residential combustors: bituminous coal, hard coal briquettes, and lignite. Emissions from these coals differ significantly and can be partially explained by differences in coal composition. For bituminous coal, particulate matter emission factors are somewhat greater than those used in current emission inventories. We observe particles for which the light absorption is weak and has a strong spectral dependence. For hard coal briquettes and lignite, emitted light absorption is low, and based on our measurements, current inventories of lightabsorbing aerosols significantly overestimate the contribution from these sources. Hard coal briquettes produce very few particles in the optically active size range. For all coals tested the size distributions required to represent the average of the emitted particles are broader than atmospheric size distributions, with geometric standard deviations between 2.2 and 3.0.

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Section: Resultsmentioning

confidence: 99%

Primary particle emissions from residential coal burning: Optical properties and size distributions

et al. 2002

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“…For the first hypothesis, the general sooting tendency is dependent on the initial fuel structure (Glassman, 1988). Furthermore, for coal combustion, Ma et al (1996) and Mitra et al (1987) have found a clear correlation between the tar production capability and the soot formation. Their conclusion is that soot formation increases with increasing tar production capability.…”

Section: Influence Of Fuel Type On Particle Emissions 755mentioning

confidence: 96%

“…In biomass combustion, the composition of the submicron particles is dominated by K 2 SO 4 and KCl (Christensen, 1995;Lind et al, 2000). During pulverized-coal combustion, soot is generated from coal when volatile matter, tar in particular, undergoes secondary reactions at high temperature in the flame surrounding devolatilized coal particles (Fletcher et al, 1997;Ma et al, 1996;Timothy et al, 1986).…”

Section: Introductionmentioning

confidence: 99%

The Influence of Fuel Type on Particle Emissions in Combustion of Biomass Pellets

Wiinikka¹,

Gebart²

2005

Combustion Science and Technology

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Three different biomass fuels (bark pellets, wood pellets and granulates made from hydrolysis residues) were burned under identical conditions to determine the effect of biomass type on the amount and composition of the combustion-generated particles under fixed-bed conditions. Significant differences in emissions of dust, submicron particles, and the shape of the particle number and mass size distributions were found between the different biomass fuels. For the particles that were dominated by ash elements, the particle emissions were correlated to the ash concentration in the unburned fuel. However, if the combustion condition allowed for organic particles, the ''sooting'' tendency of the fuel was found to become more important than the amount of ash in the fuel. Furthermore, the fuel type affects the particle emissions more than changes in reactor operating parameters.

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“…Studies on liquid or gaseous fuels usually find that a minimum temperature of 1600 K is required for soot formation [ Glassman et al , 1994]; this temperature dependence may result from kinetic limitations, with the formation of the first aromatic ring being the rate‐limiting step [ Frenklach et al , 1984]. However, coal tar contains large polyaromatic hydrocarbons that are favored as soot nuclei [ Vanderwal , 1996], so that soot formation begins at much lower temperatures (about 900 K, Ma et al [1996]). This means that low‐temperature combustion of coal can produce black carbon, and this fact is relevant not only to stokers, but also to coal used in residential combustion and other industrial processes.…”

Section: Emission Characteristicsmentioning

confidence: 99%

A technology‐based global inventory of black and organic carbon emissions from combustion

et al. 2004

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[1] We present a global tabulation of black carbon (BC) and primary organic carbon (OC) particles emitted from combustion. We include emissions from fossil fuels, biofuels, open biomass burning, and burning of urban waste. Previous ''bottom-up'' inventories of black and organic carbon have assigned emission factors on the basis of fuel type and economic sector alone. Because emission rates are highly dependent on combustion practice, we consider combinations of fuel, combustion type, and emission controls and their prevalence on a regional basis. Central estimates of global annual emissions are 8.0 Tg for black carbon and 33.9 Tg for organic carbon. These estimates are lower than previously published estimates by 25-35%. The present inventory is based on 1996 fuel-use data, updating previous estimates that have relied on consumption data from 1984. An offset between decreased emission factors and increased energy use since the base year of the previous inventory prevents the difference between this work and previous inventories from being greater. The contributions of fossil fuel, biofuel, and open burning are estimated as 38%, 20%, and 42%, respectively, for BC, and 7%, 19%, and 74%, respectively, for OC. We present a bottom-up estimate of uncertainties in source strength by combining uncertainties in particulate matter emission factors, emission characterization, and fuel use. The total uncertainties are about a factor of 2, with uncertainty ranges of 4.3-22 Tg/yr for BC and 17-77 Tg/yr for OC. Low-technology combustion contributes greatly to both the emissions and the uncertainties. Advances in emission characterization for small residential, industrial, and mobile sources and topdown analysis combining field measurements and transport modeling with iterative inventory development will be required to reduce the uncertainties further.

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Conversion of coal tar to soot during coal pyrolysis in a post-flame environment

Cited by 59 publications

References 10 publications

Primary particle emissions from residential coal burning: Optical properties and size distributions

Primary particle emissions from residential coal burning: Optical properties and size distributions

The Influence of Fuel Type on Particle Emissions in Combustion of Biomass Pellets

A technology‐based global inventory of black and organic carbon emissions from combustion

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