Kinetics of steam and CO 2 gasification of high ash coal–char produced under various heating rates

Jayaraman, Kandasamy; Gökalp, I.; Bonifaci, Elisa; Merlo, Nazim

doi:10.1016/j.fuel.2015.02.091

Cited by 102 publications

(65 citation statements)

References 47 publications

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“…These factors emphasized that an increase in thermal lag occurs on the pyrolysis of coal as the heating rate increases, which agrees well with those reported [11,19,20,45].…”

Section: Kinetic Analysissupporting

confidence: 91%

“…The char particles are produced using the heating rates of 40 • C/min, 100 • C/min, 500 • C/min and 1000 • C/min in argon ambience. The experimental setup used for the gasification tests was described in a previous study [16][17][18][19][20]. After pyrolysis, chars were cooled to ambient temperature in argon ambience.…”

Section: Methodsmentioning

confidence: 99%

“…It can be observed that the effect of particle size is insignificant at low heating rates. On the other hand, the DTG max variation is substantial at 1000 • C/min, which is increased by 20% once the particle sizes are changed from 900 m to 60 m. Due to the differences in the ash and volatile content of the particle sizes, larger particles have relatively higher content of residual mass of the char, hence, the DTG is relatively low for 900 m particles [19,20]. This can be explained by the fact that large particles provide more resistance to volatiles escape, thereby increasing the amount of secondary reactions and resulting in carbon deposition.…”

Section: Kinetic Analysismentioning

confidence: 99%

“…The DTG results show that the maximum thermal degradation (DTG max ) of coal particles shifted toward higher temperature as the heating rate increased, caused by differences in heat transfer and kinetic rates, thereby delaying sample decomposition [11,19,20,44]. Hence, the heating rate mainly influences the primary pyrolysis stage of the coal, while the maximum weight loss rate and corresponding temperature change is occurred with the raising of heating rate.…”

Section: Kinetic Analysismentioning

confidence: 99%

“…Several researchers [10][11][12][13][14][15] and recently authors [16][17][18][19][20] have reported that thermal analysis techniques such as thermogravimetric analysis and mass spectrometry (TGA-MS) have been widely used to estimate the rapid quantitative methods for the examination of processes under isothermal or non-isothermal conditions and allow for the estimation of effective kinetic parameters for various decomposition reactions and evolved gas analyzes, respectively. Due to its complexity of structure and the heterogeneity of components, the determination of the coal pyrolysis process is very difficult, which consists of a lot of physical changes and chemical reactions.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

High ash coal pyrolysis at different heating rates to analyze its char structure, kinetics and evolved species

Jayaraman

Gökalp

Bostyn

2015

Journal of Analytical and Applied Pyrolysis

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“…These factors emphasized that an increase in thermal lag occurs on the pyrolysis of coal as the heating rate increases, which agrees well with those reported [11,19,20,45].…”

Section: Kinetic Analysissupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: Kinetic Analysismentioning

confidence: 99%

Section: Kinetic Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

High ash coal pyrolysis at different heating rates to analyze its char structure, kinetics and evolved species

Jayaraman

Gökalp

Bostyn

2015

Journal of Analytical and Applied Pyrolysis

Self Cite

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High‐temperature char gasification of anthracite/petroleum coke: using biomass leachate as cheap‐effective additive

Wei

Ding

Gong

et al. 2020

Asia-Pacific J Chem Eng

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Rice straw leachate (RSL) was employed as cheap‐effective biomass‐based additive for anthracite/petroleum coke (JM/PC) gasification. The influence of RSL on high‐temperature (1,000–1,300°C) char gasification reactivity and kinetics was analyzed by thermogravimetric analysis. The results demonstrate that for PC char, catalytic effect of RSL on its gasification reactivity existed within the whole temperature range and was initially weakened and then enhanced as gasification temperature increased (turning‐point temperature, 1,200°C). For JM char, as gasification temperature increased, the influencing form of RSL on its gasification reactivity was initially presented as the weakened catalytic effect and turned into the reduced inhibition effect within 1,200–1,300°C. These phenomena were mainly attributed to the concentration and activity variations of alkali/alkaline earth metal species derived from RSL during JM/PC char gasification at different temperatures. Kinetics analysis based on conventional models indicates that random pore model (RPM) was more suitable to describe char gasification. Moreover, RSL additive could reduce the activation energy of JM char and PC char gasification by 12.71 and 43.39 kJ·mol−1, respectively, which implied that RSL help to improve char gasification kinetics and exhibited more positive effect on PC char. Kinetics analysis based on free‐model method verified the reliability and accuracy of RPM.

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Combustion characteristics of ultrafine gasified semi‐char in circulating fluidized bed

Ren

Shu

2016

Can J Chem Eng

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Coal fluidized bed gasification generates large amounts of semi‐char, which has a high carbon content. Effectively re‐burning semi‐char has become a promising way to improve overall conversion efficiency of coal gasification and use the residue carbon in the semi‐char. However, due to the ultrafine particle size (mean particle size ≈ tens of microns), nearly zero volatile content, and the graphitization structure of the semi‐char, the fluidization and combustion organization of semi‐char in a circulating fluidized bed (CFB) is difficult, leading to poor self‐sustained combustion stability and low combustion efficiency. The physicochemical properties of the semi‐char from an industrial CFB gasifier were studied. The combustion characteristics and activation energy of the semi‐char were tested using thermogravimetric analysis. The occurrence of sulphur and nitrogen in the semi‐char and fly ash after combustion were characterized with X‐ray photoelectron spectroscopy (XPS). A re‐burning experiment was carried out in a 5 t/day CFB pilot facility. The key is to build a balance between sufficient residence time to burnout and a proper fluidization velocity for bed material cycle. The effects of residence time, preheating temperature, and the ratio of preheating air to fuel on the combustion efficiency and pollutant emission was studied. The balance between the preheating time and residence time in the furnace was discussed. Results show that it can reach stable combustion in a specially designed CFB furnace without auxiliary fuel and the combustion efficiency can be higher than 98 %.

show abstract

Kinetics of steam and CO 2 gasification of high ash coal–char produced under various heating rates

Cited by 102 publications

References 47 publications

High ash coal pyrolysis at different heating rates to analyze its char structure, kinetics and evolved species

High ash coal pyrolysis at different heating rates to analyze its char structure, kinetics and evolved species

High‐temperature char gasification of anthracite/petroleum coke: using biomass leachate as cheap‐effective additive

Combustion characteristics of ultrafine gasified semi‐char in circulating fluidized bed

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