Effects of vent ducts on the reduced pressures from explosions in dust collectors

Lunn, G.A.; Nicol, A. M.; Collins, Philip; Hubbard, N.R

doi:10.1016/s0950-4230(97)00036-3

Cited by 7 publications

(5 citation statements)

References 3 publications

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“…In a study with four types of dusts varying widely in explosion characteristics, and ducts of two sizes, Lunn et al [149], have observed that the difference between the vent duct area and the effective vent area, and the explosion characteristics of the dusts are important factors in decreasing the effect of vent ducts below the levels predicted by theory. The logistics of an industrial unit often makes it necessary for the ducts to have one or more bends.…”

Section: Vent Ductsmentioning

confidence: 99%

“…The maximum flame length emitted from a vent can be up to 10 times the cube root of the vented vessel volume [147]. If too much unburned flammable material is ejected by a vent it may even get ignited by the vented flame to cause a secondary explosion [148,149]. The challenge of vent design thus extends to eliminating hazardous effects of vented material, especially the flames.…”

Section: Explosion Ventingmentioning

confidence: 99%

“…Comparative studies on the efficacy of these methods [2,12,152] reveal that: (a) the vent ratio method tends to overestimate the explosion pressure while the vent coefficient method underestimates it; (b) the K St method gives good predictions in its low ignition energy source nomographs but tends to underestimate the explosion pressure; (c) if reliable Hartman bomb data are available, the method of Schwab and Othmer yields good results. The K St method can yield vent areas up to three times larger than the experimentally determined values but it has been argued that this provides a valuable safety factor, more so when the standard test conditions under which the experimental results are generated can differ substantially from the happenings in an actual plant [149]. Eckhoff and Fuhre [153] and others have shown that in most industrial processes the dust clouds produce less violent explosion than those to which the monographs apply, but the method continues to be favored due to the safety margin it generates.…”

Section: Approaches To Vent Designmentioning

confidence: 99%

See 2 more Smart Citations

Dust explosions–Cases, causes, consequences, and control

Abbasi

2007

Journal of Hazardous Materials

407

153

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Section: Vent Ductsmentioning

confidence: 99%

Section: Explosion Ventingmentioning

confidence: 99%

Section: Approaches To Vent Designmentioning

confidence: 99%

See 1 more Smart Citation

Dust explosions–Cases, causes, consequences, and control

Abbasi

2007

Journal of Hazardous Materials

407

153

View full text Add to dashboard Cite

“…In other words, a larger bend angle leads to a stronger effective venting inhibiting effect on the explosion products. Lunn et al 17,22 studied the influence of the bend distance and length to diameter ratio of the duct on the intravessel venting overpressure. Only the relationship between the overpressure in the vessel and the duct was investigated quantitatively; the venting mechanism and the mechanism of the intraduct secondary explosion were not explained or analyzed.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on dust explosion vented through a bent duct

Pang

Zhang

Cui

et al. 2020

Process Safety Progress

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In this study, a self‐designed small cylindrical vessel was used to perform a dust explosion venting experiment through a bent duct. Based on this experiment, the influence of the bend distance and the static activation overpressure of the venting film on the explosion overpressure and the flame propagation was investigated. The results showed that both the maximum venting overpressure and pressure rise rate within the vessel increased with the decrease in the bend distance and increase in the static activation overpressure. In contrast, the duration of the combustion within the vessel exhibited the opposite trend. A typical “three‐peak” overpressure structure formed by the film rupture shock wave, secondary explosion in the duct, and continuous combustion within the vessel was observed in the duct. The third peak overpressure was dominant throughout the process. The intensity of the secondary explosion in the duct was positively correlated with the bend distance and static activation overpressure. Shorter bend distances led to greater peak‐overpressure drops after passing the bend. However, the attenuation of the secondary explosion intensity along the duct with static activation overpressure is not obvious.

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“…Siwek − described a series of experiments in a 25 m 3 vessel equipped with vent ducts of lengths 3, 6, and 10 m and diameters of 0.2 or 0.3 m. Dust clouds were generated by pneumatic filling at a rate of 15 m 3 per minute, and the P red values were found to increase linearly with increasing L d . Lunn et al investigated the effect of vent ducts on vented dust explosions in two dust collectors. The effects of vent ducts on P red was less than predicted by guidance for homogeneous dust clouds.…”

Section: Introductionmentioning

confidence: 99%

Validation of the DESC Code in Simulating the Effect of Vent Ducts on Dust Explosions

Castellanos

Skjold

Wingerden

et al. 2013

Ind. Eng. Chem. Res.

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The computational fluid dynamics (CFD) code DESC has been used to simulate a series of dust explosion experiments performed in an 18.5 m 3 vessel equipped with vent ducts of varying cross sections and lengths. The motivation behind the work is 3-fold: to validate the CFD code, to gain increased understanding of the parameters affecting dust explosion venting through ducts, and to investigate the validity of empirical correlations found in various standards and guidelines for design of explosion protection systems. Although the results from simulations agree reasonably well with experimental observations, DESC tends to underpredict the reduced explosion pressures for scenarios with vent ducts with diameters significantly larger than the vent openings. These discrepancies may be a result of inherent limitations in the model system, but poor repeatability and limited access to detailed experimental data complicates the analysis. Results from experiments and simulations are compared with predictions from various standards and guidelines for design of vent ducts in industry: EN 14491, VDI 3673, NFPA 68, and the methodology developed by FM Global. The correlations in NFPA 68, derived from the same set of experiments in the 18.5 m 3 vessel, yield the most accurate predictions. The FM Global method underestimates the reduced explosion pressure for the largest vent diameter and rear ignition and yields conservative results for smaller duct diameters. Neither experiments nor simulations support the concept of a critical duct length prescribed in EN 14491 and VDI 3673.

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Effects of vent ducts on the reduced pressures from explosions in dust collectors

Cited by 7 publications

References 3 publications

Dust explosions–Cases, causes, consequences, and control

Dust explosions–Cases, causes, consequences, and control

Experimental study on dust explosion vented through a bent duct

Validation of the DESC Code in Simulating the Effect of Vent Ducts on Dust Explosions

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