Kinetics of devolatilization and oxidation of a pulverized biomass in an entrained flow reactor under realistic combustion conditions

Jiménez, Santiago; Remacha, Pilar; Ballesteros, J.C.; Giménez, Antonio; Ballester, Javier

doi:10.1016/j.combustflame.2007.10.001

Cited by 40 publications

(41 citation statements)

References 30 publications

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“…It was found for fast heating rates relevant for pulverized fuel combustion [38][39][40][41] that the assumption of thermally thin particles is no longer valid when the biomass particle size exceeds 0.2 mm. The pinewood particles between 0.05 and 0.85 mm are completely reacted within the first second of pyrolysis at 1000 ∘ C. For a complete pyrolysis of particles N 0.85 mm, 2 s holding time is required.…”

Section: Effect Of Holding Timementioning

confidence: 99%

Influence of fast pyrolysis conditions on yield and structural transformation of biomass chars

Trubetskaya

Jensen

et al. 2015

Fuel Processing Technology

100

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Fast pyrolysis of biomass (wood, straw, rice husk) and its major components (cellulose, hemicellulose, lignin) was conducted in a wire mesh reactor. The aim of this study was to understand the influence of temperature (350-1400 ∘ C), heating rate (10-3000 ∘ C/s), particle size (0.05-2 mm) and holding time (1-4 s) on the char morphology and char yield. Scanning electron microscopy (SEM) and elemental analysis were conducted to determine the effect of operating conditions on char softening and melting during pyrolysis. The char yield decreased with heating rate for rates ≤600 ∘ C/s; above this value a similar biomass char yield was obtained. The potassium content affected the char yield stronger than other minerals, while the distribution of the three major biomass constituents (cellulose, hemicellulose, lignin) affected the char yield only to a minor degree. Moreover, it was found that the heat treatment temperature had a larger influence on the char yield than the heating rate. Scanning electron microscopy indicated different types of biomass char plasticization influenced by the applied temperatures, heating rates, particle sizes and holding times, except for the rice husk char that formed chars with a structure similar to the parental fuel at all conditions. The less severe morphological changes of rice husk char were attributed to a high silica content.

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Section: Effect Of Holding Timementioning

confidence: 99%

Influence of fast pyrolysis conditions on yield and structural transformation of biomass chars

Trubetskaya

Jensen

et al. 2015

Fuel Processing Technology

100

View full text Add to dashboard Cite

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“…16 Biagini et al experimentally characterized the reactivity and morphology of biomass chars produced under high heating rates in a drop tube reactor. 17 Karlstrom et al determined reaction orders and kinetic parameters for the oxidation of five anthracite chars and one biomass char at temperatures ranging from 1223 to 1673 K using a multivariable optimization method, in which modeled burnout profiles were fitted to experimental data from a 4 m isothermal plug flow reactor operating under 10 4 −10 5 K/s.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Effects of Particle Shape and Operating Conditions on Combustion Characteristics of Single Biomass Particles

et al. 2012

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An experimental study is performed to investigate the ignition, devolatilization, and burnout of single biomass particles of various shapes and sizes under process conditions that are similar to those in an industrial combustor. A chargecoupled device (CCD) camera is used to record the whole combustion process. For the particles with similar volume (mass), cylindrical particles are found to lose mass faster than spherical particles and the burnout time is shortened by increasing the particle aspect ratio (surface area). The conversion times of cylindrical particles with almost the same surface area/volume ratio are very close to each other. The ignition, devolatilization, and burnout times of cylindrical particles are also affected by the oxidizer temperature and oxygen concentration, in which the oxygen concentration is found to have a more pronounced effect on the conversion times at lower oxidizer temperatures.

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“…The combustion rates for cynara and cardoon particles are the slowest and the fastest, respectively. The averaged char combustion rate with the gas temperature fluctuation is higher than without the gas temperature fluctuation for cynara and Jiménez et al [23] Adanez et al, [24] Backreedy et al [25] Yang et al [26] Karampinis et al [15] pinewood particles, but the results cannot be clearly observed for willow and cardoon particles. The effect of gas temperature fluctuation on char burning time for willow and cardoon particles is also not noticeable, as shown in Table 2.…”

Section: Resultsmentioning

confidence: 99%

Char combustion of ellipsoidal particles in a hot gas with fluctuating temperature

Zhang

2016

Can J Chem Eng

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Char combustion of biomass particles is a significant thermo‐chemical conversion process. The char combustion process of biomass particles with gas temperature fluctuation is numerically investigated. Considering the non‐spherical shape of biomass particles, a fully algebraic expression of burning enhancement factor is theoretically derived to modify the char combustion rate of ellipsoidal particles. Four solid biofuel samples (cynara, pinewood, willow, and cardoon) are chosen for the calculations. The instantaneous mass variations and char combustion rates of biomass particles are calculated under different particle sphericities. Different kinetic parameters of biomass samples lead to various effects of gas temperature fluctuation on char combustion. The gas temperature fluctuation generally enhances the char combustion rate. Increasing the fluctuation frequency of gas temperature has no effect on char combustion. Under the same particle surface area, the char combustion rate is enhanced with decreasing particle sphericity.

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Kinetics of devolatilization and oxidation of a pulverized biomass in an entrained flow reactor under realistic combustion conditions

Cited by 40 publications

References 30 publications

Influence of fast pyrolysis conditions on yield and structural transformation of biomass chars

Influence of fast pyrolysis conditions on yield and structural transformation of biomass chars

Experimental Study on Effects of Particle Shape and Operating Conditions on Combustion Characteristics of Single Biomass Particles

Char combustion of ellipsoidal particles in a hot gas with fluctuating temperature

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