Ignition and explosion parameters of Colombian coals

The explosivity of coal in Colombia is usually determined by chemical analysis based on the volatile ratio. To improve the assessment of the explosivity of those coals that have led to numerous explosions in Colombian mines, 22 coals from the department of Antioquia were analyzed. Flammability characteristic parameters were determined, such as minimum temperatures and energy for ignition and the lower explosive limit. Also explosion data, ie. Pmax and Kmax values were obtained. In addition, the susceptibility to spontaneous combustion was studied by thermogravimetry and differential scanning calorimetry, together with chemical attack with hydrogen peroxide and also measuring the temperature of ignition of flammable volatiles. Finally the effect of particle size and the percentage range of limestone needed for inerting coal under two different granulometries were determined.     

Effects of ignition energy on fire and explosion characteristics of dilute hybrid fuel in ventilation air methane

Deflagration explosions of coal dust clouds and flammable gases are a major safety concern in coal mining industry. Accidental fire and explosion caused by coal dust cloud can impose substantial losses and damages to people and properties in underground coal mines. Hybrid mixtures of methane and coal dust have the potential to reduce the minimum activation energy of a combustion reaction. In this study the Minimum Explosion Concentration (MEC), Over Pressure Rise (OPR), deflagration index for gas and dust hybrid mixtures (K_st) and explosive region of hybrid fuel mixtures present in Ventilation Air Methane (VAM) were investigated. Experiments were carried out according to the ASTM E1226-12 guideline utilising a 20 L spherical shape apparatus specifically designed for this purpose.Resultsobtained from this study have shown that the presence of methane significantly affects explosion characteristics of coal dust clouds. Dilute concentrations of methane, 0.75–1.25%, resulted in coal dust clouds OPR increasing from 0.3 bar to 2.2 bar and boosting the K_st value from 10 bar m s⁻¹ to 25 bar m s⁻¹. The explosion characteristics were also affected by the ignitors’ energy; for instance, for a coal dust cloud concentration of 50 g m⁻³ the OPR recorded was 0.09 bar when a 1 kJ chemical ignitor was used, while, 0.75 bar (OPR) was recorded when a 10 kJ chemical ignitor was used.For the first time, new explosion regions were identified for diluted methane-coal dust cloud mixtures when using 1, 5 and 10 kJ ignitors. Finally, the Le-Chatelier mixing rule was modified to predict the lower explosion limit of methane-coal dust cloud hybrid mixtures considering the energy of the ignitors.     

Experimental determination of dust cloud combustion parameters of α-AlH3 powder in its charged and fully discharged states for H2 storage applications

This study discusses results of an experimental program for determination of dust cloud combustion parameters of charged and fully discharged states of metastable alane (aluminum hydride, α-AlH₃ polymorph) powder in air. The measured characterization parameters include: maximum deflagration pressure rise (ΔP_MAX), maximum rate of pressure rise (dP/dt)_MAX, minimum ignition temperature (T_C), minimum explosible concentration (MEC), and minimum ignition energy (MIE). These measured values are used for calculating the associated explosion severity (ES) index, and volume-normalized maximum rate of pressure rise (K_St). The experimental results show values of MEC and T_C of fully discharged alane to be greater than those of the charged alane but measured MIE values are about the same. Moreover, the results show higher reactivity of fully discharged alane dust cloud in air compared to its charged state. For example, ES and K_St of discharged alane dust cloud in air are about 300% and 35% greater, respectively, than ES and K_St of charged alane dust. The higher air reactivity of fully-discharged (primarily Al powder) dust cloud compared to its charged state can be attributed to the higher surface energy (J/m²) of Al compared to that of α-AlH₃. These experimental insights have safety implications in postulated risk scenarios involving light-duty vehicles powered by PEM fuel cells. The core insights and critical data provided by this contribution are useful for supporting development and promulgation of hydrogen safety standards and augmenting property databases of hydrogen storage materials.     

喷丸亚光机的危害性分析与无害化设计

从安全设备工程学的观点出发 ,分析了喷丸亚光机这一特种机械的危险因素和有害因素 ,阐述了在防尘、降噪、安全、耐用等方面所采取的相应防护措施和关键技术。提出了使该设备达到安全化、无害化的设计方法 ,使机械设计制造与工业安全卫生科学紧密结合 ,不仅具有生产功能的实用性 ,而其加工性能和相关指标达到或优于国外同类设备。     

基于专家地理信息系统(EGIS)的露天采矿烟尘污染环境效应评价模型

针对露天矿山烟尘污染源的特点 ,运用环境评价的原理和方法 ,探讨了传统评价工作中存在的不足 ,将地理信息系统 (GIS)应用到露天矿烟尘污染控制中 ,提出了基于专家地理信息系统 (EGIS)的烟尘污染环境效应评价模型 ,并评述了该模型的重要意义和发展前景     

An Integrated Approach to Reservoir Management: The Williston Reservoir Case Study

/ The management of industrial reservoirs for hydroelectric energy can cause severe impacts to surrounding communities. This study examines the generation of dust along the northern foreshore zones of Williston Reservoir in northern British Columbia. The dust is generated in the spring when the reservoir levels are low and impacts a relocated First Nations' village (Tsay Keh) at the north end of the reservoir. Data were gathered to provide an overview of the physical conditions that contribute to the dust problem, including a social survey, soil analysis, and vegetation inventory. The study provides a scoping method to assess a large-scale and complex problem with respect to dust management along a large reservoir. Methods for dust control include short- and long-term solutions that integrate the use of native vegetation along the foreshore zones of the reservoir.     

浅谈锅炉烟尘监测过程中的质量控制

从采样前准备、现场检查、现场采样等方面出发,结合实际经验,对锅炉烟尘气监测工作谈一些自己的见解。     

东北地区烟尘(气)测试中一些问题的讨论

目前东北地区以燃煤为主要能源.烟尘(气)的排放仍是大气污染综合治理的主要空中对象.我们在采样过程中经常遇到这样那样的问题,根据GB5468-91锅炉烟尘测试法和个人的工作经验对问题出现的原因和解决方法进行简单的讨论.     

城市扬尘污染现状及防治对策

扬尘是造成城市颗粒物污染严重的主要因素.论述了城市扬尘污染的现状、主要来源及其危害,并针对各种扬尘污染源提出了具体的防治对策。     

Inerting effect of N2 on explosion of LDPE dust/ethylene hybrid mixtures

Explosion flame propagation characteristics and overpressure distribution of low density polyethylene (LDPE) dust and ethylene hybrid mixture were investigated under N₂ inerting conditions using a custom-designed 12 L cylindrical explosion tank. The results showed that a small amount of ethylene could promote the explosion characteristics of LDPE dust. N₂ inerting had different inhibitory effects on the explosion flame of LDPE dust and its mixture with ethylene. The explosion overpressure strength of the LDPE dust/ethylene hybrid mixture decreased with increasing N₂ concentration. The overall suppression effect of N₂ on the explosion overpressure of the LDPE dust was better than that of the LDPE dust/ethylene hybrid mixture explosion. As the ethylene concentration increased from 0% to 2.5%, the limiting oxygen concentration decreased by 13% oxygen. This small amount of ethylene restricted the traditional inerting process. The study conclusions can provide further scientific basis for the inerting and explosion proofing design of production process equipment involving LDPE dust.