Dust explosions: A threat to the process industries

Yuan, Zhi; Khakzad, Nima; Khan, Faisal; Amyotte, Paul

doi:10.1016/j.psep.2015.06.008

Cited by 184 publications

(48 citation statements)

References 34 publications

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“…In most large scale dust explosion accidents, a series of explosions consisting of a primary weak explosion, followed by a devastating secondary explosion, has been reported [1,2,[4][5][6]. While the hazardous effect of the primary explosion is relatively small, the secondary explosions propagate with a speed of up to 1000 m/s, producing overpressures of in the range of 8-10 bar.…”

Section: Is Ddt the Only Possible Way To Explain Unconfined Dust Explmentioning

confidence: 99%

“…The interphase (particle-gas) energy exchange time is τ pg = ρ p d 2 p c p /6λNu < 1 ms, where λ = χρ g c p is the gas thermal conductivity, χ is the thermal diffusivity, c p is the heat capacity of the gas, and Nu ≈ 2 is the Nusselt number [71]. It is known that in order for ignition to occur, a gas volume with a size that is of the order of the typical flame thickness, r f (for CH 4 /air r f ≈ 2mm), has to be heated to ignition temperature to ignite a self-sustained combustion in a gas mixture. This means that the time it takes for an isolated particle to heat the surrounding gas to a level where it can ignite is relatively long (t χ ∼ r 2 /χ ≈ 500 ms).…”

Section: Radiation-induced Secondary Explosionsmentioning

confidence: 99%

“…Understanding the origin and mechanism of dust explosions is essential for minimizing the dust explosion hazard in many industrial processes, to understand their causes, prevention and mitigation methods. The danger of dust explosions is a permanent threat in various industries handling combustible or inert powders of fine particles [1][2][3][4][5][6][7]. Methane-air systems are lifethreatening mixtures, particularly in underground coal mines.…”

Section: Introductionmentioning

confidence: 99%

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Multipoint radiation induced ignition of dust explosions: turbulent clustering of particles and increased transparency

Liberman

Kleeorin

Haugen

2018

Combustion Theory and Modelling

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It is known that unconfined dust explosions consist of a relatively weak primary (turbulent) deflagrations followed by a devastating secondary explosion. The secondary explosion may propagate with a speed of up to 1000 m/s producing overpressures of over 8-10 atm. Since detonation is the only established theory that allows a rapid burning producing a high pressure that can be sustained in open areas, the generally accepted view was that the mechanism explaining the high rate of combustion in dust explosions is deflagration to detonation transition. In the present work we propose a theoretical substantiation of the alternative propagation mechanism explaining origin of the secondary explosion producing the high speeds of combustion and high overpressures in unconfined dust explosions. We show that clustering of dust particles in a turbulent flow gives rise to a significant increase of the thermal radiation absorption length ahead of the advancing flame front. This effect ensures that clusters of dust particles are exposed to and heated by the radiation from hot combustion products of large gaseous explosions sufficiently long time to become multi-point ignition kernels in a large volume ahead of the advancing flame front. The ignition times of fuel-air mixture by the radiatively heated clusters of particles is considerably reduced compared to the ignition time by the isolated particle. The radiation-induced multi-point ignitions of a large volume of fuel-air ahead of the primary flame efficiently increase the total flame area, giving rise to the secondary explosion, which results in high rates of combustion and overpressures required to account for the observed level of overpressures and damages in unconfined dust explosions, such as e.g. the 2005 Buncefield explosion and several vapor cloud explosions of severity similar to that of the Buncefield incident.

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Section: Is Ddt the Only Possible Way To Explain Unconfined Dust Explmentioning

confidence: 99%

Section: Radiation-induced Secondary Explosionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Multipoint radiation induced ignition of dust explosions: turbulent clustering of particles and increased transparency

Liberman

Kleeorin

Haugen

2018

Combustion Theory and Modelling

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“…Aluminum dust resulting from the processing or fabrication of aluminum products can form suspended dust clouds in a closed or semi-closed production environment. Exposure of these dust clouds to ignition sources (e.g., electric sparks, open flames, or hot surfaces) with sufficient energy could lead to violent explosions [1][2][3][4][5]. The over 2000 • C maximum explosion temperature of aluminum dust, when coupled with explosion-induced overpressure, will cause considerable damages [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Suppression of Aluminum Dust Explosion by Ca(H2PO4)2/RM Composite Powder with Core–Shell Structure: Effect and Mechanism

et al. 2019

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A Ca(H2PO4)2/RM composite powder suppressant with core–shell structure was prepared with modified red mud (RM) as the carrier and Ca(H2PO4)2 as the loaded particles, using a solvent–antisolvent process, in an attempt to suppress aluminum dust explosion more effectively. The suppression effects of the Ca(H2PO4)2/RM composite powder suppressant for aluminum dust flame propagation and for explosion overpressure were tested in a vertical glass tube test apparatus and a 20 L explosion vessel. The results show that the Ca(H2PO4)2/RM composite powder suppressant was more effective in suppressing aluminum dust flame propagation and explosion overpressure than either Ca(H2PO4)2 or RM powder alone. Finally, the suppression mechanism of the Ca(H2PO4)2/RM composite powder suppressant was analyzed. On the one hand, a large amount of burning heat was absorbed through the decomposition of Ca(H2PO4)2 and the melting phase transformation of the decomposition product; on the other hand, the strong isolation provided by the RM helped limit flame propagation. The strong adsorptivity of RM allowed this material to adsorb the radicals from the explosion reaction perfectly.

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“…The main ignition source causing dust explosions are flame and direct heat, following by friction sparks [51], as shown on Figure 11 Figure 11. Ignition sources for dust explosions [51] To study the possibility of ignition of a source, it is necessary to take into account the energy of the source, the time, the volume of sample affected by this energy and its spatial distribution.…”

Section: Ignition Sourcementioning

confidence: 99%

Analysis of the flammability properties of solid fuels

Áñez¹,

Nieves²

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Dust explosions: A threat to the process industries

Cited by 184 publications

References 34 publications

Multipoint radiation induced ignition of dust explosions: turbulent clustering of particles and increased transparency

Multipoint radiation induced ignition of dust explosions: turbulent clustering of particles and increased transparency

Suppression of Aluminum Dust Explosion by Ca(H2PO4)2/RM Composite Powder with Core–Shell Structure: Effect and Mechanism

Analysis of the flammability properties of solid fuels

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