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最新英文期刊文献(气体与粉尘爆炸)推荐

Interaction between gas explosion flame and deposited dust

瓦斯爆炸火焰与沉积煤尘的相互影响

Process Safety and Environmental Protection, Volume 111, October 2017, Pages 775-784

Yifan Song, Qi Zhang, Weiwei Wu

Abstract:In order to study the patterns for local gas explosion inducing deposited dust combustion, the process of dust kicking-up and participating in gas explosion is numerically simulated. The pressure wave of local gas explosion kicks up deposited dust, then the flame triggers raised dust to burn and further spread. Coal dust participation can accelerate the methane-air flame propagation in the tube, which is shown by the increasing of flame propagating velocity, the flame temperature and the combustion duration. The temperature–time curves of complex flames display an apparent structure of double peaks, and the FWHMs (full width at half maxima) of temperatures vary at different deposited coal dust concentrations. The FWHM at 80 g/m3 has no significant difference compared with the FWHM with no dust. Therefore, 80 g/m3 can be esteemed as the lower limit for the secondary explosion (dust participating and methane/dust mixed-combusting). Furthermore, the effect of pressure wave velocity on dust kicking-up is studied. It is found that dust diffuses sufficiently when the pressure wave velocity lies in the range of 140 m/s–300 m/s.

 

The influence of dust particles on the stability of foam used as dust control in underground coal mines

地下煤矿煤尘颗粒对尘控泡沫稳定性的影响

Process Safety and Environmental Protection, Volume 111, October 2017, Pages 740-746

Wanxing Ren, Jingtai Shi, Qing Guo, Qiankun Zhao, Lei Bai

Abstract:In China, the presence of significant levels of coal dust suspended in the air is a major health hazard and one of the main causes of disasters in coal production. A new technique was developed to control suspended dust by making use of foam. In this study, the foam structure and foam stability under the influence of dust were investigated. It was found that while foam stability is a key factor in the effectiveness of dust control, dust particles also affect foam stability. In this research, foam was classified to dry or wet foam based on its mass fraction. In this regard, it was observed that dry foam is more stable because of its polyhedral structure. Moreover, a series of experiments were applied to determine the relationship between dust particles in foams with different foaming multiples and foam drainage. The results show that dry foam with dust particles has a lower drainage rate, and it is more stable than foam without dust particles. Such improved foam stability could potentially extend the application of foam technology to dust control in underground coal mines in future.

 

Dust explosion propagation and isolation

粉尘爆炸传播与隔离

Journal of Loss Prevention in the Process Industries, Volume 48, July 2017, Pages 320-330

Jérôme Taveau

Abstract:Industrial processes handling combustible dusts usually comprise numerous pieces of equipment, such as grinders, mixers, dryers, classifiers, dust collectors, and storage hoppers, interconnected by a more or less complex network of pipes and conveying systems.

If a combustible dust cloud is accidentally ignited in a process enclosure, large amounts of heat and high pressures are generated in milliseconds. The resulting dust deflagration may, or may not compromise its structural integrity depending if the vessel is adequately protected or not. Nevertheless, the deflagration pressure will push the fireball through any existing openings, including process interconnections. The flame front will stretch and speed up due to increased turbulence, accentuating the severity of the initial event. Ultimately, a more violent secondary deflagration can take place when the flame reaches the next process enclosure, such that existing protection measures may well fail under these aggravated conditions.

While the need to protect process enclosures from a dust deflagration (either by venting or suppression) is widely recognized, the isolation of interconnections, on the other hand, generally receives less attention. This can be explained by some persistent myths and misconceptions about dust explosion propagation leading to a false sense of security.

This paper unravels three common myths about dust explosion propagation, introduces explosion isolation technology and demonstrates the importance of large-scale testing for the validation of explosion isolation designs.

 

Determination of the burning velocity of gas/dust hybrid mixtures

气体/粉尘混合物燃烧速率计算

Process Safety and Environmental Protection, Volume 109, July 2017, Pages 704-715

Nicolas Cuervo, Olivier Dufaud, Laurent Perrin

Abstract:The laminar flame speed is an essential input for Computational Fluid Dynamics simulation programs aiming to predict the effects of explosions. In this study, an approach to assess fundamental flame propagation properties from the analysis of the flame velocity as a function of its stretching and hydrodynamic instabilities was developed. A numerical tool was developed to analyse videos of propagating flames in order to estimate their unstretched burning velocities.

Markstein’s theory, developed for gases and assuming a linear relation between the flame stretch and its speed, was then extended to dust clouds and hybrid mixtures of starch and methane. At first, the approach was validated with pure methane and was extended to pure starch and hybrid mixtures of both compounds.

Finally, it appears that hybrid mixtures, especially when the gas concentration is greater than the lower explosive limit, can present a synergetic effect enabling faster flame propagation with regard to pure gas flames. Indeed, the stretching of a gas flame is strongly influenced by the addition of dusts. Nevertheless, for lower gas concentrations and larger dust concentrations called ‘dust-driven regime’, the presence of powders tends to limit the flame velocity to that of the less reactive compound, i.e. the dust.