保护层一次爆除技术在船闸开挖中的应用

在贵港航运枢纽工程船闸开挖中，采用了孔间微差和宽孔距小梯段孔底设柔性保护层的一次钻爆技术，确保了基岩的完整性。     

除尘风机工况调节的实践

对常用的几种风机工况点调节方法进行了概述,并结合自身的实践论述了它的优点和缺点。     

CFD modeling and simulation of turbulent fluid flow and dust dispersion in the 20-L explosion vessel equipped with the perforated annular nozzle

A three-dimensional CFD model was developed to simulate the turbulent flow field induced by dust feeding and the associated dust dispersion within the 20-L explosion vessel equipped with the perforated annular nozzle. The model was validated against experimental data for pressure and root mean square velocity.Simulation results have shown that the turbulent kinetic energy is rather uniformly distributed and its values are significantly lower than those attained with the rebound nozzle. Furthermore, the perforated annular nozzle is able to generate a uniform dust/air cloud. However, a consistent fraction of the dust remains trapped inside the nozzle and, thus, it does not contribute to the explosion process.     

A new shock tube configuration for studying dust-lifting during the initiation of a coal dust explosion

The traditional defence against propagating coal dust explosions is the application of dry stone dust. This proven and effective safety measure is strictly regulated based on extensive international experience. While new products, such as foamed stone dust, offer significant practical benefits, no benchmark tests currently exist to certify their dust lifting performance in comparison to dry stone dust. This paper reviews the coal dust explosion mechanism, and argues that benchmark testing should focus on dust lifting during the initial development of the explosion, prior to arrival of the flame. In a practical context, this requires the generation of shock waves with Mach numbers ranging from 1.05 to 1.4, and test times of the order of 10's to 100's of milliseconds. These proposed test times are significantly longer than previous laboratory studies, however, for certification purposes, it is argued that the dust lifting behaviour should be examined over the full timescales of an actual explosion scenario. These conditions can be accurately targeted using a shock tube at length scales of approximately 50 m. It is further proposed that useful test time can be maximised if an appropriately sized orifice plate is fitted to the tube exit, an arrangement which also offers practical advantages for testing. The paper demonstrates this operating capability with proof-of-concept experiments using The University of Queensland's X3 impulse facility.     

Dynamic approach to risk management: Application to the Hoeganaes metal dust accidents

Several major accidents caused by metal dusts were recorded in the past few years. For instance, in 2011, three accidents caused by iron dust killed five workers at the Hoeganaes Corp. facility in Gallatin, Tennessee (USA). In order to prevent such accidents, a dynamic approach to risk management was defined in this study. The method is able to take into account new risk notions and early warnings and to systematically update the related risk. It may be applied not only in the design phase of a system, but also throughout the system lifetime as a support to a more precise and robust decision making process. The synergy of two specific techniques for hazard identification and risk assessment was obtained: the Dynamic Procedure for Atypical Scenarios Identification (DyPASI) and the Dynamic Risk Assessment (DRA) methods. To demonstrate its effectiveness, this approach was applied to the analysis of Gallatin metal dust accidents. The application allowed collecting a number of risk notions related to the plant, equipment and materials used. The analysis of risk notions by means of this dynamic approach could have led to enhanced hazard identification and dynamic real-time risk assessment. However, the approach described is effective only if associated to a proper safety culture, in order to produce an appropriate and robust decision making response to emerging risk issues.     

Some myths and realities about dust explosions

The necessary conditions for a dust explosion to occur are well-expressed by the explosion pentagon: (i) fuel, (ii) oxidant, (iii) ignition source, (iv) mixing of the fuel and oxidant, and (v) confinement of the resulting mixture. While it might seem relatively straightforward to prevent or mitigate a dust explosion by simply removing one of the pentagon elements, the field of dust explosion risk reduction is more complex. Building upon previous work by the author and other dust explosion researchers, the theme of the current paper is that this complexity is partially rooted in several erroneous beliefs. These beliefs ignore the realities found with full consideration of appropriate scientific and engineering principles. Several such myths and their factual counterparts are presented with an illustrative example.     

矿山粉尘的湿式纤维层过滤阻力类比研究

为提高矿山粉尘收集效率,对除尘器湿式过滤层纤维丝过滤阻力进行理论分析,建立粉尘粒子通过除尘器湿式纤维丝时的阻力理论模型,自行设计了湿式纤维层过滤实验模拟系统,模拟矿山粉尘特点进行了实验研究,对理论模型参数进行了无量纲修正,进一步完善粉尘湿式过滤的阻力理论公式.实验表明,该理论在实际应用中具有较高的准确性.经修正后的理论曲线不仅与实验曲线的趋势保持一致,同时数值上也基本吻合,具有良好的代表性.     

Numerical simulation study of dust concentration distribution regularity in cavern stope

Based on the theory of gas-solid two-phase flow and the characteristics of cavern stope a model of dust migration was established. The dust concentration changing of cavern stope by ventilation in 20 min after blasting and the dust trajectory in different wind speed were simulated by Fluent Software. The results show that distribution of dust concentration is significantly affected by flow field of airway in cavern, and the dust concentration of inlet is higher than that of outlet and the highest one on the corner of inlet’s side. In the stope, the smaller the wind speed of inlet is, the shorter of dust can be captured, settled and discharged, the more obviously affected by the trajectory of gas flow field. It goes into the stage of clean cycle emissions after 60 s, the speed of dust concentration dropped is the biggest between 0 s and 70 s, the main dust in stope is respirable dust after 70 s, it needs much time to settlement.According to the measured data of metal mining, approximately 87% of dust was generated during the drilling and blasting in the mine (Wang, 1979). A lot of dust with high concentrations was produced during the cavern stope blasting and it was difficult to be discharged. It can help choose the right speed to rule out the dust quickly which produced during cavern blasting, if the dust concentration distribution and the dust migration law of different inlet velocity in the cavern can be verified, what’s more, the labor productivity can be increased. It has great significance for choosing reasonable ventilation parameters, reducing dust hazards of stope to researching the dust concentration distribution regularity in the stope.     

受压浮煤自燃过程试验研究

矿井采空区遗煤自燃大部分为处于受压状态下的自燃。为观察压力对浮煤自燃过程的影响,采用自制的浮煤加载自燃试验装置对受压浮煤层与自然堆积状态下的自燃过程进行试验研究。结果表明:加载对浮煤的自燃过程确实存在一定影响。加载会加快浮煤层的升温速度,缩短自然发火期,降低最小浮煤层厚度,改变采空区"三带"的划分;加载对厚度介于0.8～1.2 m之间浮煤自燃过程影响最大;随着压力的增加,压力对浮煤自燃过程的影响逐渐减弱,当压力小于1 600 N时,压力的增加对浮煤自燃过程的影响较明显,当压力大于1 600 N时,压力的增加对浮煤自燃过程的影响变小,当压力大于2 600 N时,压力的增加对浮煤自燃过程几乎无影响。     

Combined reticular blind drainage and vertical hierarchical drainage system for landfills located in areas with high rainfall and high groundwater level

A novel water control technology that combines the features of a reticular blind drainage system and a vertical hierarchical drainage system is developed and applied in the Yanziyan Sanitary Landfill, which is located at an area (Loudi City, Hunan Province, China) with high rainfall and high groundwater level. The reticular blind drain system, which was installed on the bottom and side walls of the landfill site, can conveniently guide the flow of groundwater out of the site while preventing a disorganized flow of groundwater. The vertical hierarchical drainage system was installed to separate rainfall water and leachate in the landfill site, thus efficiently reducing the pressure of leachate treatment. The whole drainage system plays a key role in foundation stabilization by seepage control and separation and in the instant drainage of rainfall water. The leachate reduction efficiency of the drainage technology was calculated in terms of leachate production before (336519 m³) and after (29664 m³) technology application. Over 90% of leachate derived from rainfall water and groundwater inflow was avoided upon installation of the vertical hierarchical drainage and reticular blind drainage systems. The technology can thus be popularized and applied for water control in landfills located in areas with high rainfall and high groundwater level. The proposed technology can be used to alleviate the pressure of leachate treatment and to reduce the risk of instability.