Coal devolatilization at high temperatures

Kobayashi, Hironobu; Howard, Jack B.; Sarofim, Adel F.

doi:10.1016/s0082-0784(77)80341-x

Cited by 584 publications

(336 citation statements)

References 7 publications

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“…The two-competing-rate model was employed to predict the biomass devolatilization rate and the volatile matter yield [33]. Even though the volatile matter contains many gaseous species, it was reasonable to represent the released volatile matter by a single virtual material, because the reaction rate of the volatile matter was limited by the turbulent mixing rate of the evolved gas and the oxidizer at the near-burner condition.…”

Section: (A) Combustion Modelmentioning

confidence: 99%

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Biagini

Yang

et al. 2013

Combustion and Flame

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This version is available at https://strathprints.strath.ac.uk/53528/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Abstract:In this work, the flame characteristics of torrefied biomass were studied numerically under hightemperature air conditions to further understand the combustion performances of biomass.Three torrefied biomasses were prepared with different torrefaction degrees after by releasing 10%, 20%, and 30% of volatile matter on a dry basis and characterized in laboratory with standard and high heating rate analyses. The effects of the torrefaction degree, oxygen concentration, transport air velocity, and particle size on the flame position, flame shape, and peak temperature are discussed based on both direct measurements in a laboratory-scale furnace and CFD simulations. The results primarily showed that the enhanced drag force on the biomass particles caused a late release of volatile matter and resulted in a delay in the ignition of the fuelair mixture, and the maximum flame diameter was mainly affected by the volatile content of the biomass materials. Furthermore, oxidizers with lower oxygen concentrations always resulted in a larger flame volume, a lower peak flame temperature and a lower NO emission. Finally, a longer flame was found when the transport air velocity was lower, and the flame front gradually moved to the furnace exit as the particle size increased. The results could be used as references for designing a new biomass combustion chamber or switching an existing coal-fired boiler to the combustion of biomass.

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Section: (A) Combustion Modelmentioning

confidence: 99%

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Biagini

Yang

et al. 2013

Combustion and Flame

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“…The mass loss rate of the coal particles from devolatilization is determined from Ubhayakar's two rates model [25] and Kobayashi's model [26]. Both models define two competing devolatilization rates of the Arrhenius form.…”

Section: Combustion Modelsmentioning

confidence: 99%

“…Kobayashi's devolatilization model [26] was also employed to investigate the sensitivity to devolatilization models. Reaction rates of Kobayashi's model are slower than Ubhayakar's model by several orders of magnitudes at the same temperature.…”

Section: Comparisons Between Devolatilization Modelsmentioning

confidence: 99%

Eulerian–Eulerian multi-fluid methods for pulverized coal flames with nongray radiation

Cai

Handa

Modest

2015

Combustion and Flame

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“…Devolatilization was modeled by the two competing rates model proposed by Kobayashi, et al [16] R are competing rates that may control the devolatilization over different temperature ranges so that the rate of devolatilization is given as: …”

Section: Devolatilization Modelmentioning

confidence: 99%

CFD Modeling of Devolatilization and Combustion of Shredded Tires and Pine Wood in Rotary Cement Kilns

Mtui¹

2013

AJEE

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Abstract:Computational fluid dynamics (CFD) has been used to study the devolatilization and combustion of large particles of shredded scrap tire "rubber" and pulverized pine wood "biomass" in a rotary cement kilns. The CFD model constitutes of modeling the hydrodynamics within the rotary kiln, heat transfer, devolatilization and co-combustion of rubber and biomass blends. Equivalent particle diameters of 1 mm and 2 mm for biomass and rubber, respectively, were used to simulate the process conditions and co-combustion in cement rotary kilns. The ratios of biomass substitution were varied from 5% to 20% on mass basis. The effect of the percentage of biomass content on the temperature distribution and devolatilization rate as well as wall heat transfer rate are presented. Results indicate that up to 20% biomass blend provides improved combustion characteristics compared with combustion of scrap tire alone. Further, the devolatilization rate was found to improve remarkably when scrap tire is blended with biomass. Most importantly, the biomass blend was found to increase the flame spreading and penetration, consequently improving the wall heat transfer rate, therefore providing favorable conditions for heat transfer to the cement clinker. The present study provides additional knowledge for future investigations on the use of biomass residues and some industrial wastes as alternative fuels for rotary cement kilns. That is, the use of alternative fuels in rotary cement kilns has a potential for economic improvement and environmental sustainability.

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Coal devolatilization at high temperatures

Cited by 584 publications

References 7 publications

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Eulerian–Eulerian multi-fluid methods for pulverized coal flames with nongray radiation

CFD Modeling of Devolatilization and Combustion of Shredded Tires and Pine Wood in Rotary Cement Kilns

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