Measurement and modeling of individual carbonaceous particle temperature profiles during fast CO2 laser heating

Tripathi, Ashish; Vaughn, Chris L.; Maswadeh, Waleed M.; Meuzelaar, Henk L. C.

doi:10.1016/s0040-6031(02)00030-8

Cited by 3 publications

(9 citation statements)

References 24 publications

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“…However, its duration time of a high heating rate is the longest, and the final temperature is also the highest. This result is consistent with the conclusion by Tripathi et al − The existence of cross-points in weight loss and temperature histories among the samples with different particle sizes is one of the important features of coal particles under laser-heating conditions, which is distinctively different from other heating systems. Because the area per mass unit of small particles is larger than that of large particles, when particle temperatures rise to some extent, the radiation term becomes important, the thermal loss of the smaller particles is much greater than that of larger ones; therefore, the thermal-balance temperature is also low.…”

Section: Resultssupporting

confidence: 93%

“…Bhattacharya and Wall investigated the development of the emittance of coal particles during devolatilization and char particles (45−125 μm) at temperatures between 473 and 1273 K and discussed the magnitude of potential errors in pyrometric temperature measurement. Recently, Tripathi et al , measured and modeled temperature profiles of individual carbonaceous particles and coal particles from three kinds of different rank coals using a CO 2 laser pyrolysis system with two-color micropyrometry. They predicted that intraparticle gradients between surface temperature and bulk average radius temperature fall within the estimated error range (100 K) of two-color pyrometry measurements and thus can be ignored for particle sizes of 80−120 μm.…”

Section: Introductionmentioning

confidence: 99%

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Devolatilization Characteristics of Coal Particles Heated with CO₂ Laser Controlled by Double Shutters. 1. An Experimental Investigation

Gao

Ishigaki

2006

Energy Fuels

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A CO 2 laser controlled well by specially designed double shutters was used to heat uniformly dispersed coal particles in nitrogen. The temperatures of the coal particles were measured using a highly accurate multiplepoint, two-color temperature measurement system. The average performance and characteristics of three kinds of coals with different volatile content were carefully investigated at various experimental conditions. The conclusions are as follows: (1) the proximate volatile matter content, particle size, and laser intensity are the three most important factors in the devolatilization process of coal particles under the laser heating condition;(2) the devolatilization processes can be separated into two parts by the proximate volatile matter contents of three coals, which suggests that two devolatilization schemes exist in each coal; (3) the effect of laser intensities on the devolatilization processes indicates that the devolatilization process cannot be well-characterized by only laser intensity; (4) the existence of cross points in the curves of weight loss and particle temperatures among the samples with different sizes are one of the important features of laser heating, which is distinctively different from other heating methods; (5) the variation in V/V 0 values of all three kinds of coals with particle temperatures exponentially depends on coal particle temperatures, and can be expressed as V/V 0 ) 9.0 × 10 -4 exp(5.3 × 10 -3 T p ) with R 2 ) 0.8833; (6) the change in V/V 0 of W coal with different particle sizes is highly dependent on particle temperatures and can be expressed as V/V 0 ) 1.3 × 10 -3 exp(5.2 × 10 -3 T p ) with R 2 ) 0.9169; (7) a comprehensive expression, which includes volatile matter content, in situ energy density per surface area of coal particle, final particle temperature, and in situ particle properties, such as swelling, shrinking, emissivity, etc., should be further investigated.

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Section: Resultssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Devolatilization Characteristics of Coal Particles Heated with CO₂ Laser Controlled by Double Shutters. 1. An Experimental Investigation

Gao

Ishigaki

2006

Energy Fuels

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“…Bhattacharya and Wall investigated the development of emittance of coal particles during devolatilization and char particles (45−125 μm) at temperatures of 473−1273 K and discussed the magnitude of potential errors in pyrometric temperature measurement. Recently, Tripathi et al , measured and modeled temperature profiles of individual carbonaceous particles and coal particles from three types of different rank coals, using a CO 2 laser pyrolysis system with a two-color micropyrometry under pulverized coal combustion conditions. They predicted that the intraparticle gradients between the surface temperature and the bulk average radius temperature fall within the estimated errors range (100 K) of two-color pyrometry measurements and thus can be ignored for the particle size range of 80−120 μm.…”

Section: Introductionmentioning

confidence: 99%

“…(2) The sphericity correction factor is 0.75 for all coal particles, irrespective of coal rank and particle size;…”

Section: Introductionmentioning

confidence: 99%

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Devolatilization Characteristics of Coal Particles Heated with a CO₂Laser Controlled by Double Shutters: A Simulation Investigation^†

Gao¹,

He²,

Nomura³

2010

Energy Fuels

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An empirical model was established based on measurements of devolatilization characteristics of coal particles (18.7%, 32.7%, and 43.0% VM; 0.14, 0.20, and 0.30 mm, respectively) heated at a heating rate of 10 3 -10 4 K/s by a well-controlled CO 2 laser with double shutters and a high-accuracy two-color pyrometer. The conclusions obtained are as follows: (1) particle temperature (T p ), volatile yield (V), heating rate (HR), and in situ energy density flux (F ed ) during devolatilization can be well-predicted by solving an energy conservation equation and a devolatilization rate equation with two competing reaction rates; (2) the preexponential factor and activation energy of the two reactions are A 1 = (1.7249-1.8936) Â 10 2 s -1 , E 1 = (2.6248-3.5447)Â10 4 J/mol, A 2 =2.6Â10 6 s -1 , and E 2 =1.6740Â10 5 J/mol, respectively, which are obtained by fitting our experiment data; (3) the final volatile yield (V f ) is dependent on the laser intensity (Q L ), the particle size (D n ), and the proximate volatile matter content (V 0 ), and it can be well-predicted by a regressive equation of V f with Q L , D n , and V 0 ; (4) a modified Merrick's heat capacity correlation can be used to predict the temperature history of coal particles heated at a rate of 10 3 -10 4 K/s with excellent agreement; (5) the heats of devolatilization, which are given as -0.5244, -0.6629, and -0.7348 MJ/kg for the three coals used in this study, are suitable values for predictions; (6) the sum of the heat of devolatilization (ΔH d ) and energy loss per unit mass volatile yield (ΔH vl ), which can be represented as ΔH d þ ΔH vl =-0.01046 MJ/kg, is a suitable value for predicting particle temperatures and volatile yields for all three coals; (7) the measured histories of weight loss are imperative for predicting the temperature and the devolatilization kinetics of coal particles heated at a high heating rate; and (8) the swellingshrinking ratios, absorptivity, emissivity, thermal capacity, and heat of devolatilization of coal particles at high heating rates should be measured for better predictions.

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Process characteristics investigation of simulated circulating fluidized bed combustion combined with coal pyrolysis

Liang

Wang

Ji-cheng

2007

Fuel Processing Technology

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Measurement and modeling of individual carbonaceous particle temperature profiles during fast CO2 laser heating

Cited by 3 publications

References 24 publications

Devolatilization Characteristics of Coal Particles Heated with CO₂ Laser Controlled by Double Shutters. 1. An Experimental Investigation

Devolatilization Characteristics of Coal Particles Heated with CO₂ Laser Controlled by Double Shutters. 1. An Experimental Investigation

Devolatilization Characteristics of Coal Particles Heated with a CO₂Laser Controlled by Double Shutters: A Simulation Investigation^†

Process characteristics investigation of simulated circulating fluidized bed combustion combined with coal pyrolysis

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Measurement and modeling of individual carbonaceous particle temperature profiles during fast CO2 laser heating

Cited by 3 publications

References 24 publications

Devolatilization Characteristics of Coal Particles Heated with CO2 Laser Controlled by Double Shutters. 1. An Experimental Investigation

Devolatilization Characteristics of Coal Particles Heated with CO2 Laser Controlled by Double Shutters. 1. An Experimental Investigation

Devolatilization Characteristics of Coal Particles Heated with a CO2Laser Controlled by Double Shutters: A Simulation Investigation†

Process characteristics investigation of simulated circulating fluidized bed combustion combined with coal pyrolysis

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Devolatilization Characteristics of Coal Particles Heated with CO₂ Laser Controlled by Double Shutters. 1. An Experimental Investigation

Devolatilization Characteristics of Coal Particles Heated with CO₂ Laser Controlled by Double Shutters. 1. An Experimental Investigation

Devolatilization Characteristics of Coal Particles Heated with a CO₂Laser Controlled by Double Shutters: A Simulation Investigation^†