Ignition characteristics of single coal particles from three different ranks in O2/N2 and O2/CO2 atmospheres

Khatami, Reza; Stivers, Chris; Levendis, Yiannis A.

doi:10.1016/j.combustflame.2012.06.019

Cited by 210 publications

(123 citation statements)

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“…The nature of the heterogeneous ignition of anthracite and semianthracite particles is however different to that of lignite coals, previously studied in this laboratory [5]. Although the lignite coal particles contained sufficient amounts of volatile matters for gas-phase ignition, their extensive fragmentation and the small fragment sizes were the main reasons for their heterogeneous ignition [5]. The much higher volatile content bituminous coal particles of this study ignited in the gas phase (homogeneously).…”

Section: Discussionmentioning

confidence: 77%

“…In the case of a few semi-anthracite particles, gas-phase (homogeneous) ignition took place due to their higher volatile matter content as discussed earlier. The nature of the heterogeneous ignition of anthracite and semianthracite particles is however different to that of lignite coals, previously studied in this laboratory [5]. Although the lignite coal particles contained sufficient amounts of volatile matters for gas-phase ignition, their extensive fragmentation and the small fragment sizes were the main reasons for their heterogeneous ignition [5].…”

Section: Discussionmentioning

confidence: 95%

“…The combustion and emission studies of bituminous coals has been well-documented in the aforementioned studies of Khatami et al and Kazanc et al in this laboratory [4,5,6] as well as in other studies including those of [7][8][9][10]. However, studies on anthracite and semi-anthracite coal particle ignition and combustion are scarce.…”

Section: Introductionmentioning

confidence: 92%

“…Coal particle combustion experiments were conducted under quiescent gas conditions (i.e., no gas flow in the drop-tube furnace) in order to equalize the axial temperature profiles of N 2 -and CO 2 -containing furnace gases, as documented by Khatami et al [5].…”

Section: Furnace Gas Temperature and Compositionmentioning

confidence: 99%

“…Previous work in this laboratory contrasted the combustion behaviors of single solid fuel particles of a bituminous high-volatile type-A coal, three low rank coals (low carbon content and low heating value coals): a sub-bituminous and two different lignites, as well as biomass (sugarcane bagasse) under air and under simulated dry oxyfiring conditions [4,5]. This work aims at examining the combustion behavior of additional bituminous coals (high-and medium-volatile types-B) as well high rank coals (high carbon content and high heating value coals), i.e., anthracite and semi-anthracite.…”

Section: Introductionmentioning

confidence: 99%

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Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions

Riaza

Khatami

Levendis

et al. 2014

Combustion and Flame

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111

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A fundamental investigation has been conducted on the combustion behavior of single particles (75-150 μm) of four coals of different ranks: anthracite, semi-anthracite, medium-volatile bituminous and high-volatile bituminous. A laboratory-scale transparent laminar-flow drop-tube furnace was used to burn the coals, electricallyheated to 1400 K. The experiments were performed in different combustion atmospheres: air (21%O 2 /79%N 2 ) and four simulated dry oxy-fuel conditions: 21%O 2 /79%CO 2 , 30%O 2 /70%CO 2 , 35%O 2 /65%CO 2 and 50%O 2 /50%CO 2 . The ignition and combustion of single particles was observed by means of three-color pyrometry and high-speed high-resolution cinematography to obtain temperature-time histories and record combustion behavior. On the basis of the observations made with these techniques, a comprehensive examination of the ignition and combustion behavior of these fuels was achieved. Higher rank coals (anthracite and semi-anthracite) ignited heterogeneously on the particle surface, whereas the bituminous coal particles ignited homogeneously at the gas phase. Moreover, deduced ignition temperatures increased * Corresponding author: Tel.: 001 (617) 373-3806; Fax: 001 (617) 373-2921 E-mail address: y.levendis@neu.edu 2 with increasing coal rank and decreased with increasing oxygen concentrations.Strikingly disparate combustion behaviors were observed depending on the coal rank.The combustion of bituminous coal particles took place in two phases. First, volatiles evolved, ignited and burned in luminous enveloping flames. Upon extinction of these flames, the char residues ignited and burned. In contrast, the higher rank coal particles ignited and burned heterogeneously. The replacement of the background N 2 gas of air with CO 2 (i.e., changing from air to an oxy-fuel atmosphere) at the same oxygen mole fraction impaired the intensity of combustion. It reduced the combustion temperatures and lengthened the burnout times of the particles. Increasing the oxygen mole fraction in CO 2 to 30-35% restored the intensity of combustion to that of air for all the coals studied. Volatile flame burnout times increased linearly with the volatile matter content in the coal in both air and all oxygen mole fractions in CO 2 . On the other hand, char burnout times increased linearly or quadratically versus carbon content in the coal, depending on the oxygen mole fraction in the background gas.

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Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 92%

Section: Furnace Gas Temperature and Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions

Riaza

Khatami

Levendis

et al. 2014

Combustion and Flame

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191

111

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Oxyfuel Combustion forCO₂Capture

Yan

2015

Handbook of Clean Energy Systems

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Oxyfuel combustion is one of the technologies for carbon dioxide ( CO 2 ) capture and storage ( CCS ) in fossil‐fuel‐based power systems to mitigate global greenhouse gas ( GHG ) emissions. When introducing oxyfuel combustion into the power systems, physical and chemical processes of the combustion differ from conventional combustion, and the energy penalty for CCS has significant impacts on the system operation and performance, similar to combustion process, heat transfer, flue gas properties, and emission control. Around these topics, dozens of oxyfuel‐related projects were launched within this decade in the worldwide, and many techno‐economic assessments for oxyfuel technology including competitive technologies (pre‐/post‐combustion and emerging technologies) are continuously being published. Although the technologies for oxyfuel combustion are relatively well understood today, it is only investigated experimentally in lab and pilot‐scale combustion equipment. The estimated costs of electricity and CO 2 avoidance costs are varied by uncertainties from economical assessments from different referenced databases and from restricted regulation of different countries and regions. Therefore, all addressed issues must be clarified and proved to be feasible deployment for the commercial scale CCS plants to cope with emission targets according to Copenhagen Accord to reduce GHG emission and mitigate world temperature rising.

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Fundamentals and Technology of Oxy‐Coal Combustion

Fujimori

Ito

Zhang

2016

Handbook of Combustion

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As one of the most attractive technologies for carbon capture, oxy‐fuel combustion of coal has been studied worldwide. Some important results of fundamental studies and practical systems of oxy‐fuel combustion are introduced in this chapter. According to the results of fundamental experiments, a slower flame propagation velocity in a O 2 /CO 2 atmosphere requires a higher O 2 concentration to obtain a stable combustion in oxy‐fuel mode compared to air mode. CO 2 and H 2 O gasification each have effects on reducing the char particle temperature and increasing the char consumption rate. In oxy‐fuel mode, gasification reactions between char and CO 2 or H 2 O can result in a high devolatilization rate and a clearly different char structure. As with simulations of heat transfer in the boiler for oxy‐fuel combustion, the new weighted sum of gray‐gases model for calculating gas radiation properties should be developed to adapt to very high concentrations of CO 2 and H 2 O in the flue gas. However, particle radiation generally plays a more important role than gas radiation. Computational fluid dynamics simulation data obtained with the Callide furnace have shown an oxy‐fuel combustion of 27 vol.% O 2 with flue gas recycling to have a similar heat absorption to air combustion. Fundamental and applications research are still required, however, to optimize boiler design and system configurations.

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Ignition characteristics of single coal particles from three different ranks in O2/N2 and O2/CO2 atmospheres

Cited by 210 publications

References 40 publications

Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions

Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions

Oxyfuel Combustion forCO₂Capture

Fundamentals and Technology of Oxy‐Coal Combustion

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Ignition characteristics of single coal particles from three different ranks in O2/N2 and O2/CO2 atmospheres

Cited by 210 publications

References 40 publications

Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions

Single particle ignition and combustion of anthracite, semi-anthracite and bituminous coals in air and simulated oxy-fuel conditions

Oxyfuel Combustion forCO2Capture

Fundamentals and Technology of Oxy‐Coal Combustion

Contact Info

Product

Resources

About

Oxyfuel Combustion forCO₂Capture