低瓦斯矿井瓦斯爆炸事故的主要原因及防治对策

从理论和实际两方面分析了近期发生在一些低瓦斯矿井的瓦斯爆炸事故,结合对福建煤矿曾经发生的瓦斯爆炸事故的分析和研讨,认为发生瓦斯爆炸事故的主要原因有:对瓦斯防治重视不够、未能准确地确定瓦斯的爆炸下限浓度及瓦斯混合气体在强点火能下会降低瓦斯爆炸浓度下限等主观上的原因,还有因采深加大致使瓦斯涌出量增加、瓦斯监测系统不到位等客观上的原因。着重从大量的试验证明了在强点火能下瓦斯混合气体爆炸浓度下限大幅降低的事实,并提出了相关的防治对策。研究成果对瓦斯防治具有重要的实际意义。     

天然气钻井井口安全距离研究分析

分析天然气钻井井场可能发生的事故类型及事故的破坏程度,选择适合的事故后果模型,对天然气井井喷失控后可能发生的蒸气云爆炸及硫化氢扩散的后果进行量化分析,根据超压-冲量准则、热剂量准则和硫化氢扩散行为规律,计算出爆炸波、爆炸火球及硫化氢扩散的危害范围。笔者建立了天然气钻井井口安全距离的计算模型,并提出一种确定安全距离的方法。通过计算给出不同无阻流量、不同硫化氢体积含量的20种条件下的天然气钻井井口安全距离,并应用该模型对某含硫气井井口安全距离进行了计算。实例表明,该方法具备实用性,值得在天然气井选址规划中推广和使用。     

Modeling of n-butane ignition, combustion, and preflame oxidation in the 20-l vessel

The objective of the study reported herein is to simulate various physical and chemical phenomena accompanying fuel-rich n-butane–oxygen mixture preparation, ignition, preflame oxidation, and combustion in the standard 20-l explosion vessel, by applying mathematical models. Based on the computational fluid dynamics (CFD) simulations of the mixing process and natural convection of the ignition kernel, as well as on the analysis of the detailed reaction mechanism of n-butane oxidation, laminar flame propagation, and self-ignition, possible explanations for the phenomena observed experimentally have been suggested. The results of the study indicate that seemingly inflammable mixtures can become hazardous depending on the mixture preparation procedure and forced ignition timing.     

Post-explosion observations of experimental mine and laboratory coal dust explosions

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) and the Mine Safety and Health Administration (MSHA) conducted joint research on dust explosions by studying post-explosion dust samples. The samples were collected after full-scale explosions at the PRL Lake Lynn Experimental Mine (LLEM), and after laboratory explosions in the PRL 20-L chamber and the Fike 1 m³ chamber. The dusts studied included both high- and low-volatile bituminous coals. Low temperature ashing for 24 h at 515 °C was used to measure the incombustible content of the dust before and after the explosions. The data showed that the post-explosion incombustible content was always as high as, or higher than the initial incombustible content. The MSHA alcohol coking test was used to determine the amount of coked dust in the post-explosion samples. The results showed that almost all coal dust that was suspended within the explosion flame produced significant amounts of coke. Measurements of floor dust concentrations after LLEM explosions were compared with the initial dust loadings to determine the transport distance of dust during an explosion. All these data will be useful in future forensic investigations of accidental dust explosions in coal mines, or elsewhere.     

Determination of turbulent burning velocities of dust air mixtures with the open tube method

Correlating turbulent burning velocity to turbulence intensity and basic flame parameters-like laminar burning velocity for dust air mixtures is not only a scientific challenge but also of practical importance for the modelling of dust flame propagation in industrial facilities and choice of adequate safety strategy. The open tube method has been implemented to measure laminar and turbulent burning velocities at laboratory scale for turbulence intensities in the range of a few m/s. Special care has been given to the experimental technique so that a direct access to the desired parameters was possible minimising interpretation difficulties. In particular, the flame is propagating freely, the flame velocity is directly accessible by visualisation and the turbulence intensity is measured at the flame front during flame propagation with special aerodynamic probes. In the present paper, those achievements are briefly recalled. In addition, a complete set of experiments for diametrically opposed dusts, starch and aluminium, has been performed and is presented hereafter. The experimental data, measured for potato dust air mixtures seem to be in accordance with the Bray Gülder model in the range of 1.5 m/s<u′<3.5 m/s. For a further confirmation, the measurement range has been extended to lower levels of turbulence of u′<1.5 m/s. This could be achieved by changing the mode of preparation of the dust air mixture. In former tests, the particles have been injected into the tube from a pressurised dust reservoir; for the lower turbulence range, the particles have been inserted into the tube from above by means of a sieve–riddler system, and the turbulence generated from the pressurised gas reservoir as before. For higher levels of turbulence, aluminium air mixtures have been investigated using the particle injection mode with pressurised dust reservoir. Due to high burning rates much higher flame speeds than for potato dusts of up to 23 m/s have been obtained.     

“Vybuchovy trojuhelnik”: A software tool for evaluation of explosibility of coal mine atmosphere

Rescue operations during mine fires or methane explosions are highly dangerous for rescue workers. The knowledge of the composition of the coal mine atmosphere and the calculations of its explosibility may help to increase the safety of the rescuers. In the Czech Republic, a system called “Mine Gas Laboratory” (DPL) has been used for these purposes. The DPL allows measurement of the composition of the mine atmosphere and transmits the data necessary for evaluation to the surface. Up to now the explosibility evaluation of the coal mine atmosphere has depended either on the rescuers’ experience or on software code calculation. The code called “Vybuchovy trojuhelnik” (explosion triangle) is a graphical computing system intended for fast assessment of explosibility of fuel–air mixture. This article introduces the code and describes two simple methods of explosibility evaluation. The first method is “explosion triangle analysis”—a graphical method based on empirical graphs transformed into equations. The second method uses thermodynamic calculation based on chemical balance dynamics and Gibbs and Helmholtz energy. According to the requirements of the Czech Bureau of Mining (CBU) and Central Mine Rescue Service (HBZS), the code solves the problems of explosion triangle for both standard and non-standard coal mine atmosphere compositions. Unfortunately, the atmosphere composition must be introduced manually due to the unknown format of the data transmitted from the old DPL model. On 1 September 2005, a project started to develop a new system for on-line monitoring and atmosphere explosibility evaluation. The system should be able to measure CO₂, O₂, CH₄, H₂ and CO concentrations as well as the wind speed, temperature and humidity. The “Vybuchovy trojuhelnik” code will be used as a basis for explosibility evaluation, and an on-line connection with the new model of DPL will be established.     

两次金汞齐—冷原子吸收光谱法测定大气中的痕量气态总汞

本文作者在已有仪器的基础上进行简单改装，建立了两次金汞齐—冷原子吸收光谱法测定大气中的微量气态总汞的方法。研究表明，这种方法最低检出限为０．０５ｎｇ；１００μｌ饱和汞蒸气连续测定结果表明其相对标准偏差＜１．４１％。在０～２．０ｎｇ汞量范围内标准工作曲线线性关系良好。运用该法，对贵州省万山汞矿、丹寨汞矿、清镇汞污染农田、省农科院和中国科学院地球化学研究所等地大气气态总汞进行了测定。这种分析方法还可以运用到其它环境样品微量汞的测定。     

输油站库冬季消防稳高压系统的改进

介绍储运分公司北方输油站队，通过选用安全、防爆的数字显示温度控制器等技术手段，对储罐区消防给水管网裸露阀门及连接管段的防冻处理，实现冬季消防稳高压系统正常运行的施工工艺，并详细介绍了防爆数字显示温度控制器的工作原理及施工步骤。     

镁厂回转窑除尘系统防燃防爆措施

镁厂忽视回转窑除尘系统的防燃防爆措施,已发生多起燃爆事故。本文提出多种防止燃爆的措施,实施后效果良好。     

可燃气体(液体蒸气)的爆炸极限与最大允许氧含量的对比研究

通过实验研究了可燃气体(液体蒸气)的爆炸极限规律,从全新的角度分析了各种浓度可燃气体(液体蒸气)的最大允许氧含量的规律,并运用数值分析原理拟合出其规律函数,可从理论上求得各种浓度可燃气体(液体蒸气)的最大允许氧含量值。通过爆炸极限和最大允许氧含量规律的对比研究,分析了两者相辅相成的重要关系,指出两者从不同角度界定了可燃气体(液体蒸气)的爆炸范围,是衡量可燃气体(液体蒸气)爆炸危险性的两个重要参数。