Combustion behavior in air of single particles from three different coal ranks and from sugarcane bagasse

Levendis, Yiannis A.; Joshi, Kulbhushan; Khatami, Reza; Sarofim, Adel F.

doi:10.1016/j.combustflame.2010.09.007

Cited by 203 publications

(137 citation statements)

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“…The combustion studies of free-falling coal particles were performed in an electricallyheated laminar-flow drop-tube furnace, a detailed description of which has been provided elsewhere [14]. Here only a brief description of the reactor is given.…”

Section: Experimental Apparatus and Proceduresmentioning

confidence: 99%

“…In Eq. A.2, a f is the final particle radius after extinction, which herein is calculated based on the ash content in the parent coal composition and assuming shrinking core combustion and comparable char and ash residue densities [14]. Average deduced ignition temperatures for the four coals of the current study in air and different oxy-fuel environments.…”

Section: Calculation Of Diffusion-limited Burnout Timesmentioning

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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188

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: Experimental Apparatus and Proceduresmentioning

confidence: 99%

Section: Calculation Of Diffusion-limited Burnout Timesmentioning

confidence: 99%

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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188

111

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“…With anthracite less than 10% and bituminous from 5 to 6%, biomass fuels can lose up to 90% of their masses during the process of devolatilization [1]. The devolatilization of biomass and coal has been extensively investigated in [6][7][8][9] In numerical simulations, most researchers for simplicity considered the combustion of solid fuels occurring in two individual steps. The first one is the combustion of volatiles and the second one is the combustion of char, neglecting the interaction between the two steps.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the heterogeneous combustion processes of solid fuels

Alganash

Paul

Watson

2015

Fuel

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“…Standard deviation bars are shown on each point. The radiation intensity signals captured by the pyrometer during the combustion of biomass particles were strong and it was comparable to than those captured during combustion of coal particles under identical experimental conditions [118], especially during the phase of volatiles combustion.…”

Section: Flame Temperaturementioning

confidence: 71%

“…Previous studies in this laboratory burned single particles from five different ranks of coals [100,117,118] in the same DTF, in air, also at Tg=1350 K. Their size was 75-90 μm, which is a size commonly burned in pulverized coal boilers. Burn-out times for lignite, sub-bituminous and bituminous coal particles were in the same range as those of the torrefied biomass particles mentioned above.…”

Section: Combustion Burn-out Timementioning

confidence: 99%

Observations on the combustion of torrefied biomass

Tarakcioglu¹

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This thesis examines observations on the combustion of different types of torrefied biomass. The targeted biomass types were waste crop, herbaceous, and woody; they included Corn straw, DDGS, Rice husk, Miscanthus, Bagasse, and Beechwood. Combustion of renewable biomass is of technological interest because it is considered to be nearly carbon-neutral. Furthermore, torrefaction of biomass improves the raw biomass properties and makes more "coal-like".Torrefied biomass has lower volatile matter content, higher fixed carbon content and higher energy content than raw biomass. It is also having low moisture content and it is less biodegradable. In this work, all biomass samples were torrefied at T= 275 °C for half an hour in nitrogen. Thereafter, torrefied biomass was size classified by sieving to obtain size cuts of (75-90) µm, (180-212) µm, (180-212) µm, (212-300) µm, (300-350) µm, (350-500) µm. The experimental setup that was used in this investigation consisted of an electrically-heated drop-tube furnace, operated at wall temperature 1400 K. A three-color pyrometer was interfaced with the furnace and a high-speed high-resolution camera, to record the entire luminous particle combustion profiles of individual particles.As identification of the maximum biomass particle size for combustion in an existing boiler is important, this work observed the time-temperature profiles of the aforementioned particle size and contrasted them to those of typically-used coal particles. It was forward that torrefied biomass particles in the size range of 212−300 μm burned in similar times as those of 75-90 μm coal.

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Combustion behavior in air of single particles from three different coal ranks and from sugarcane bagasse

Cited by 203 publications

References 50 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

Numerical investigation of the heterogeneous combustion processes of solid fuels

Observations on the combustion of torrefied biomass

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