Rapid devolatilization of small coal particles

Kimber, G.M.; Gray, M. D.

doi:10.1016/0010-2180(67)90028-4

Cited by 104 publications

(34 citation statements)

References 3 publications

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“…An increase of the particle temperature due to the oxidation of volatiles was also reported by Seeker et al (1981). Devolatilization rates and yields increase with panicle temperature have also been observed in experiments by Kimber and Gray ( 1967) (1973) suggested that oxygen complex fonnation at the surface and char activation may also be important at this early stage of conversion. After the apparent rates reached the maximum, they decreased with time.…”

Section: High Temperature Conversionmentioning

confidence: 63%

Thermally induced structural changes in coal combustion. Final report

Flagan¹,

Gavalas²

1992

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Section: High Temperature Conversionmentioning

confidence: 63%

Thermally induced structural changes in coal combustion. Final report

Flagan¹,

Gavalas²

1992

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“…Also, the higher the heating rate to the coal particles, the higher the temperature of maximum weight loss rate. High heating rate results in a more extensive thermal fragmentation of coal's molecular structure and suppresses secondary reactions and the loss of fixed carbon [14,15]. Thus, a high heating rate may shift the reactions to a much higher temperature range [16,17].…”

Section: Resultsmentioning

confidence: 99%

Reactivity study of combustion for coals and their chars in relation to volatile content

Lee

Kim

2009

Korean J. Chem. Eng.

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To determine the effect of volatile matter on combustion reactivity, the pyrolysis and combustion behavior of a set of four (R, C, M and K coals) coals and their chars has been investigated in a TGA (SDT Q600). The maximum reaction temperatures and maximum reaction rates of the coals and their chars with different heating rates (5-20 o C/ min) were analyzed and compared as well as their weight loss rates. The volatile matter had influence on decreasing the maximum reactivity temperature of low and medium rank coals (R, C and M coals), which have relatively high volatiles (9.5-43.0%), but for high rank coal (K coal) the maximum reactivity temperature was affected by reaction surface area rather than by its volatiles (3.9%). When the maximum reaction rates of a set of four coals were compared with those of their chars, the slopes of the maximum reaction rates for the medium rank coals (C and M coals) changed largely rather than those for the high and low rank coals (R and K coals) with increasing heating rates. This means that the fluidity of C and M coals was larger than that of their chars during combustion reaction. Consequently, for C and M coals, the activation energies are lower (24.5-28.1 kcal/mol) than their chars (29.3-35.9 kcal/mol), while the activation energies of R and K coals are higher (25.0-29.4 kcal/mol) than those of their chars (24.1-28.9 kcal/mol).

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“…Although this reaction is the stoichiometric sum of Reactions I and II, this model considers it to be a third, independent gasification reaction. Reaction III, arbitrarily 10. JOHNSON assumed to occur in the development of this model to facilitate correlation of experimental data, has been suggested by Blackwood and McGrory (16) as being necessary in such a system.…”

Section: D(na* + Nao) Jk K2(t)mentioning

confidence: 96%

Kinetics of Bituminous Coal Char Gasification with Gases Containing Steam and Hydrogen

Johnson

1974

Advances in Chemistry

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Quantitative correlations developed to describe coal char gasification kinetics are consistent with experimental data obtained under a wide range of conditions with both differential and integral contacting systems. The correlations are developed using data obtained at constant environmental conditions with a thermobalance apparatus and a differential fluid bed system at 1500°-2000°F and 1-70 atm with a variety of gases and gas mixtures. The correlations are based on an idealized model of the gasification process which consists of three consecutively occurring stages: devolatilization, rapid-rate methane formation, and low-rate gasification./Correlations to define quantitatively the effects of pertinent intensive ^ variables on the kinetics of coal or coal char gasification reactions are necessary for the rational design of commercial systems to convert coal to pipeline gas. The available information which can be applied to the development of such correlations is relatively limited, particularly be cause the data reported from many studies conducted with integral contacting systems reflect, in part, undefined physical and chemical behavior peculiar to the specific experimental systems used. Although some differential rate data have been obtained with various carbonaceous materials, they cover only narrow ranges of the conditions potentially applicable to commercial gasification systems.For the last several years the Institute of Gas Technology (IGT) has been conducting a study to obtain fundamental information on the gasification of coals and coal chars; this information could be used with selected literature information to develop engineering correlations which 145

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Rapid devolatilization of small coal particles

Cited by 104 publications

References 3 publications

Thermally induced structural changes in coal combustion. Final report

Thermally induced structural changes in coal combustion. Final report

Reactivity study of combustion for coals and their chars in relation to volatile content

Kinetics of Bituminous Coal Char Gasification with Gases Containing Steam and Hydrogen

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