Motion of single pulverized coal particles in a hot gas flow field

Lee, Hookyung; Choi, Sangmin

doi:10.1016/j.combustflame.2016.04.012

Cited by 36 publications

(18 citation statements)

References 12 publications

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“…Therefore, the particle separation pulverisation, sieving and friction separation.The friction separator inclined planes that separate out the spherical particles by translational and rotational motions. Shapes such as extremely flat and for this experiment becausetheir varying drag coefficients cause Lee et al [38] reported statistical variations of the particle configuration, which indicated the probability distribution of the particle for the experimentalreproducibility. The dynamic motion and of the particle were influenced by the ignitionbehaviour.…”

Section: Table 2organic Compositions Of Sewage Sludgementioning

confidence: 69%

“…Therefore, the particle separation process of pulverisation, sieving and friction differently inclined planes theirtranslational and rotational motion particles, are inappropriate for random trajectories. Lee et al [38] reported statistical variations of the particle this cross flow mixing configuration irregular burning particle for the trajectories of the particle were influenced by the Table 3.Thermal treatment condition Table should decrease withincreasing carbon ratio during the torrefaction , raw sludge particles resemble a stiffclay with numerous surface has been previously removed. The particlesare brittle and pulverising process.…”

Section: Table 2organic Compositions Of Sewage Sludgementioning

confidence: 99%

“…The dynamic motion and of the particle were influenced by the ignitionbehaviour. [38] reported statistical variations of the particle trajectories in , which indicated the probability distribution of the he dynamic motion and The sewage sludge particles were prepared in two size groups; Generally, a biomass particle has a less luminosity, compared with a coal particle and, to detect their apparent flame, a biomass Generally, a biomass particle has a lower particle density, a smaller volatile flame size and less luminosity, compared with a coal particle and, to detect their apparent flame, a biomass particle size over 150 µm is required depending on the type of biomass [ are normally below 100 μm [36]. However, sludge particles of this we evaluated the initial gas temperature and velocity as the particles were heated and investigated the highly-mixed turbulent region.…”

Section: Table 2organic Compositions Of Sewage Sludgementioning

confidence: 99%

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Flame structures and ignition characteristics of torrefied and raw sewage sludge particles at rapid heating rates

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Lee

Choi

et al. 2017

Fuel

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Torrefactionis a promising method for improving the quality of pulverised solid fuel, as itincreases the flame stability,radiative heat transfer and energy density of the fuel.Raw sewage sludge contains less fixed carbon and more ash compounds than other biomasses; consequently, it has poorenergy quality witha long ignition delay and forms arelatively low, sooty flame. In this study,we directly investigate the combustion behavioursof particles with varying degrees of torrefaction by burning them at 1340 K.Thetorrefied particles were prepared at different temperatures(473 K or 573 K) for different residence times (10minor 30min).The experimental parameters examined were the size range of the particles (150-215μmand 255-300 μm)and the O 2 percentage(10-40%).The particles wereentrained from a 3 cold carrier gas into a hot gas stream, igniting a volatile flame that was extinguished a few millisecondslater. These temporal variations in the burning particles weredetected byin-situ high speed photography (7000 frames/s).Thetorrefactiondegree affected the flame structure and varied the ignition delay, due to the mismatched reactivity and soot formation at rapid heating rates. The mosttorrefied sludge particlesexhibited a relatively luminous volatile cloudand a large flame, while preserving the duration of volatile combustion. These observations confirm theimproved pulverised combustion of the torrefied sludge particles. We also obtained valuable flame parameters (radius, intensity and combustion time) of the differentlytorrefied sludge particles.

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Section: Table 2organic Compositions Of Sewage Sludgementioning

confidence: 69%

Section: Table 2organic Compositions Of Sewage Sludgementioning

confidence: 99%

Section: Table 2organic Compositions Of Sewage Sludgementioning

confidence: 99%

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Flame structures and ignition characteristics of torrefied and raw sewage sludge particles at rapid heating rates

Mock

Lee

Choi

et al. 2017

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“…The velocities of post-combustion gas and cold carrier gas in a cross-jet apparatus have been discussed by Lee et al [33]. The particle velocities during the release of volatile matter vary according to these physical quantities, so all experiments were performed under identical vertical and horizontal velocities: ~1 m/s for the post-combustion gas and 2.5 m/s for the cold carrier gas.…”

Section: Environmental Conditionsmentioning

confidence: 99%

“…First, the raw wood particle had a remarkably fibrous structure with a high aspect ratio, and the external physical structure of the coal particle was an irregular blocky shape with angular transitions. These appreciably different shapes can play an important role in particle motion, temperature gradient and ignition [33,35].…”

Section: Physical Formation Of the Four Particles From Sem Imagesmentioning

confidence: 99%

Burning characteristics of single particles of coal and wood mixtures for co-firing in an upward-flowing hot gas stream

Mock

Lee

Choi

et al. 2017

Fuel Processing Technology

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This study presents the comparative burning behaviours of single solid particles of coal and biomass mixtures for co-firing. In this experimental investigation, a direct observation approach was used to investigate the ignition, flame characteristics and combustion times by means of high-speed photography at 7,000 frames per second. Single particles were entrained into a hot gas stream at 1,340 K and a rapid heating rate at 10 4-10 5 K/s. The apparent volatile flames from the prepared particle size groups were observed within 20-50 milliseconds. To assess the effect of oxygen concentration, particles were burned for their flame characteristics in a range of 10%-40% O2. The test particles were sieved into three size groups (215-255 μm, 255-300 μm and 300-350 μm) to assess the effect of particle size. Special particles for the co-firing effect were collected individually from two types of mixed pellet: 20:80 and 50:50 coal/wood. Pure sub-bituminous coal and wood particles were also prepared in order to compare their combustion behaviours. In the experimental setup with a cross-injection configuration, sequential combustion processes were effectively and clearly described in terms of particle displacement with time. The experimental results showed distinguishable flame characteristics from single particles of coal, 50:50 coal/wood, 20:80 coal/wood and wood, including soot flame size and intensity. The impact of high coal-blending ratio caused an increase in the flame size and intensity and the ignition time was close to that of pure coal particles. Quantitative measurements of combustion events on co-firing particles were also discussed in relation to significant impacts of the particle size and the oxygen concentration.

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Numerical simulation analysis of the induced thrust on a char particle in reaction process

et al. 2022

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The force exerted on particles is of great significance to the flow and reaction characteristics of particles in gasifier. In this study, the unbalanced thrust, especially its magnitude, of a single char particle induced by chemical reactions during combustion process is investigated numerically, based on the random distribution of active sites.It is revealed that the nonuniform distribution of active sites directly leads to the nonuniform absorption of reactants and release of products, which accounts for the net induced thrust on particles. The effects of active site ratio, ambient gas temperature and particle diameter on the induced thrust of reacting particles were investigated. The results show that the induced thrust on particles could be equal to the magnitude of particle gravity. The induced thrust is determined by the nonuniformity of carbon distribution on char surface. The net thrust is enhanced with the increase of specific carbon consumption rate.

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Motion of single pulverized coal particles in a hot gas flow field

Cited by 36 publications

References 12 publications

Flame structures and ignition characteristics of torrefied and raw sewage sludge particles at rapid heating rates

Flame structures and ignition characteristics of torrefied and raw sewage sludge particles at rapid heating rates

Burning characteristics of single particles of coal and wood mixtures for co-firing in an upward-flowing hot gas stream

Numerical simulation analysis of the induced thrust on a char particle in reaction process

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