镁粉爆炸特性和惰化抑爆的实验研究

采用20 L球形爆炸测试装置,考察了镁尘浓度、镁粉粒度、点火能量对镁粉爆炸过程热力学参数Pmax、动力学参数(dP/dt)max的影响;选取CaC03粉末作为惰化剂,考察惰化剂含量、情化剂粒度对镁粉爆炸抑制性能的影响,提出了预防镁粉爆炸、降低爆炸危害的本质化安全对策.结果表明,镁尘浓度、点火能量越高,爆炸危害越大;镁粉...     

碳酸盐对密闭空间粉尘爆炸压力影响的试验研究

为了预防和缓解工业粉尘爆炸并研究惰性粉尘对粉尘爆炸的惰化作用,在Siwek 20 L球形爆炸装置内,针对高爆镁粉和高灰分煤粉,选用碳酸钙(CaCO3)、碳酸氢钠(NaHCO3)、碳酸氢钾(KHCO3)等3种碳酸盐作为惰化剂,讨论惰化剂浓度、粒径及点火能量对最大爆炸压力的影响。结果表明,惰化剂粒径越小,浓度越高,对粉尘爆炸的惰化作用越强;粉尘爆炸的净升压与点火能量无关,点火头主要起引燃作用;当惰化剂浓度递增至60%时以上,粉尘爆炸压力急剧下降,直至不爆。此外,CaCO3的抑制效果明显优于NaHCO3、KHCO3,故推荐采用CaCO3来控制粉尘爆炸风险。     

超细Al(OH)3惰化粉体对铝合金抛丸废弃物粉尘的爆炸防控效果试验研究

为探究超细粉体惰化剂对铝合金抛丸伴生粉尘爆炸特性的影响规律，利用标准化Hartmann试验装置及自行搭建的试验平台，对不同惰化比(ε)条件下高纯度铝粉尘和铝合金抛丸废弃物粉尘爆炸传播特性进行试验研究。试验结果显示：不同类型的铝粉尘在不同惰化比条件下的爆炸敏感度、爆炸传播强度以及爆炸火焰传播形态演化等方面特性存在较大差异。由于高纯度铝粉尘燃烧反应活性高，最小点火能量和爆炸下限质量浓度分别是铝合金抛丸废弃物粉尘的6%和53.3%,其爆炸火焰传播速度峰值是铝合金抛丸废弃物粉尘的2.1倍。因此，在工程实践中不宜将高纯度铝粉尘相关爆炸参数作为铝合金抛丸作业现场燃烧爆炸风险评估依据。同时，当惰化比提高到30%时，铝合金抛丸废弃物粉尘的点火敏感性大幅降低，爆炸无法形成有效火焰进而传播，且在爆炸发生后很短时间内便会发生自行熄灭，即使在强点火条件下，也未发生火焰持续传播现象。因此，在铝合金抛丸生产现场采用添加一定量超细Al(OH)₃粉体以作为抑爆措施的惰化剂具有一定的可行性。     

密闭空间中甘薯粉爆炸特性的试验研究

利用20 L球形爆炸测试装置探寻甘薯粉尘在密闭空间内的爆炸特性.测得甘薯粉的爆炸下限质量浓度,研究质量浓度,粒度和点火能量对爆炸猛烈度(最大爆炸压力和最大压力上升速率)以及燃烧特续时间的影响.结果表明:粒径较小时,甘薯粉爆科较猛烈,燃烧持续时间较短；随着质量浓度的增加,燃烧持续时间减少,最大压力上升速率逐渐增大并趋于稳定,而最大爆压呈现先增后减,并且存在一个最佳浓度范围,使粉尘爆炸最猛烈；最大爆压和上升速率随点火能量的增强而增大,较强的点火能量能显著改善低质量浓度粉尘的“爆炸不良”效应.将甘薯粉的爆炸下限质量浓度爆炸猛烈度与锌粉、镁粉和烟煤粉进行对比,发现甘薯粉的爆炸风险远高于烟煤粉和锌粉.     

超细CaCO3惰化剂对铝合金抛光伴生粉尘爆炸的防控效果*

为探究超细粉体惰化剂对铝合金抛光伴生粉尘爆炸特性的影响规律,利用标准化实验装置及自行搭建的实验平台,在对爆炸基本参数进行测试的基础上,分别研究超细CaCO3粉体对抛光废弃物粉尘点燃敏感度的钝化作用以及对爆炸火焰传播进程的惰化效果,并在相同条件下与同等粒径高纯度铝粉的实验效果进行比对。研究结果表明:铝合金抛光废弃物粉尘最小点火能量为280 mJ,而同等粒径高纯度铝粉最小点火能量为35 mJ;在铝合金抛光废弃物粉尘质量浓度为300 g/m3条件下,发生爆炸的火焰传播速度峰值为7.4 m/s,约为高纯度铝粉的57%,铝合金抛光废弃物粉尘的爆炸敏感度及猛烈度均低于高纯度铝粉;当超细CaCO3粉体的惰化比为30%时,可将铝合金抛光废弃物粉尘的最小点火能量钝化至约1 J,爆炸火焰失去持续传播能力,惰化作用效果充分显现。     

点火能量对粉尘爆炸下限浓度的影响

运用20L标准粉尘爆炸特性测试装置对不同粉尘在不同点火能量时的爆炸下限浓度进行测试,以此方法研究粉尘爆炸下限浓度随点火能量的变化规律。试验过程分别采用2. 5 k J、5 k J、10 k J点火能量对石松子粉、石墨粉、铝粉、金属打磨粉尘、纸粉、PVC粉、纺织粉、烟叶粉的爆炸下限浓度进行测试。试验结果显示粉尘爆炸下限浓度随点火能量的增加总体呈下降趋势;对于不易点燃的粉尘,其爆炸下限浓度随点火能量的增加将急剧下降。石墨粉随点火能量增加爆炸下限浓度急剧下降,铝粉、石松子粉和金属打磨粉尘受点火能量影响较小,对纸粉、纺织、烟叶粉尘影响中等。高点火能量可以扩大点火源波及的区域,从而使更多粉尘参与初始爆炸及其后的传播过程,这对于不易点燃粉尘的爆炸传播影响较大,而对于易燃粉尘的爆炸传播影响不大。为了更好的涵盖各种粉样的测试情况,也为了更加安全的指导作业现场粉尘防爆实践,推荐采用10 k J点火能量测试不易点燃的粉尘的爆炸下限。     

外部条件对玉米淀粉粉尘爆炸特性的影响

为了探明外部条件对玉米淀粉粉尘爆炸特性参数的影响,利用20 L球形爆炸装置进行试验测试,探讨了点火能量及粉尘含水量对粉尘爆炸特性的影响,对比研究了CaCO_3和Al(OH)_3两种惰性介质的抑爆效果。结果表明:随点火能量增加,粉尘最大爆炸压力和最大升压速率呈线性上升,在高质量浓度下,粉尘爆炸压力受点火能量的影响更显著;添加CaCO_3和Al(OH)_3能够降低玉米淀粉的爆炸压力,相对于CaCO_3的物理抑爆,Al(OH)_3的物理-化学抑爆效果更佳;玉米淀粉粉尘的最大爆炸压力及爆炸升压速率随粉尘含水量降低而不断增大。     

玉米淀粉粉尘爆炸危险性研究

为研究玉米淀粉粉尘爆炸危险性,采用哈特曼管式爆炸测试装置和20 L球爆炸测试装置对200目(<75μm)以下的玉米淀粉粉尘爆炸危险性进行评估,基于静电火花和粉尘质量浓度对粉尘爆炸的影响,对玉米淀粉的静电火花最小点火能量、爆炸下限质量浓度、最大爆炸压力和爆炸指数进行了研究,根据试验结果对玉米淀粉爆炸危险性进行分级。试验结果表明:温度在25℃,喷粉压力为0.80 MPa,粉尘质量浓度在250～750 g/m3范围内,粉尘的最小点火能量随着粉尘质量浓度增加而降低,其最小点火能量在40～80 mJ之间;在点火能量为10 kJ时,粉尘爆炸下限质量浓度在50～60 g/m3之间;在粉尘质量浓度为750 g/m3时,爆炸压力达到最大,为0.66 MPa;在粉尘质量浓度为500 g/m3时,爆炸指数达到最大,为17.21 MPa.m/s,其粉尘爆炸危险性分级为Ⅰ级。     

基于20 L球罐的多相混合物扩散模拟

为更好地探索多相混合物的爆炸特性，以铝粉、乙醚、空气为研究对象，基于20 L球型爆炸罐建立三维计算模型，对气固两相和气液固三相混合物的分散过程进行数值模拟，以分析不同多相混合物分散过程的差异，并为测量多相混合物爆炸下限时的点火延迟时间设定提供参考。监测分析铝粉浓度粒子分布、流场内部湍流动能以及液相体积百分数等的演化过程，讨论混合物分散效果的差异，并确定测量爆炸下限的点火延迟时间。研究结果表明:实验工况下，液相的存在会降低粉尘云团的湍流动能、降低其扩散速度，并使粉尘云内部浓度更均匀。测量多相混合物爆炸下限时，三相混合物的最佳点火延迟时间早于气固两相混合物10~20 ms。     

EVA树脂粉尘/甲烷/空气杂混物爆炸特性

在20 L爆炸实验装置中,开展了3种不同中值粒径的EVA树脂粉尘/甲烷/空气所组成的杂混物爆炸特性研究,探究了甲烷浓度对粉尘爆炸下限、最大爆炸压力的影响。结果表明,尽管添加的甲烷气体浓度低于爆炸下限,仍使得粉尘爆炸下限得以降低,粒径较大的EVA III粉尘,当甲烷体积分数为1%时,爆炸下限降低约25%;粒径较小的EVA I粉尘,当混入甲烷体积分数为4%时,爆炸下限则降低80%;甲烷体积分数每增加1%,可燃粉尘最大爆炸压力上升约10%,但对于粒径较小的EVA I粉尘,当甲烷体积分数为4%时,最大爆炸压力的上升呈现突变趋势,上升近50%。     

Explosibility of fine graphite and tungsten dusts and their mixtures

To evaluate the explosion hazard of ITER-relevant dusts, a standard method of 20-l-sphere was used to measure the explosion indices of fine graphite and tungsten dusts and their mixtures. The effect of dust particle size was studied on the maximum overpressures, maximum rates of pressure rise, and lower explosive concentrations of graphite dusts in the range 4 μm to 45 μm. The explosion indices of 1 μm tungsten dust and its mixtures with 4 μm graphite dust were measured. The explosibility of these dusts and mixtures were evaluated. The dusts tested were ranked as St1 class. Dust particle size was shown to be very important for explosion properties. The finest graphite dust appeared to have the lowest minimum explosion concentration and be able to explode with 2 kJ ignition energy.     

点火延迟时间对粉尘最大爆炸压力测定影响的研究

根据粉尘云形成时颗粒分散及沉降的时间效应,指出目前国际通行的球型爆炸装置采用固定点火延迟时间测定粉尘最大爆炸压力的方法具有不确定性,并以煤粉为介质在20 L标准爆炸球装置上进行系列爆炸实验,研究装置点火延迟时间对粉尘爆炸压力的影响。结果表明:点火延迟时间对粉尘爆炸压力测定有十分显著的影响,不同粒径粉尘的最大爆炸压力有不同点火延迟时间,目前仅以气相湍流度所确定的固定点火延迟时间下,所测粉尘最大爆炸压力可能严重偏离实际。     

固体惰性介质对煤粉爆炸压力的影响研究

通过对固体惰性介质在减轻煤粉爆炸作用的实验研究,给出影响固体惰化剂作用效果的主要影响因素。实验分别选用来自加拿大和中国的3种煤粉和石灰石,对每种实验样品的成分、粒度都进行分析。用20L球形容器进行实验,测定煤粉中加入不同含量的石灰石后煤粉爆炸的Pmax和(dp/dt)max值。结果表明,石灰石能够起到减轻煤粉爆炸影响的作用,并且随着煤粉粒度的减小,要达到相同的抑爆效果需要的石灰石的用量将加大。     

Explosibility parameters for mixtures of pulverized fuel and ash

This paper reports the results of experiments done to examine the explosibility of pulverized fuel dusts (two different coals and petroleum coke) and their waste products (bottom and fly ashes). Tests were conducted for the fuel dusts alone and also blended with other fuels and ashes. The explosion parameters of interest were maximum pressure and rate of pressure rise, and ignition energy and temperature. Petroleum coke was found to present a lesser explosion hazard than the coals. Admixture of either coal or petroleum coke with fly ash resulted in explosible mixtures at volatile contents dependent on the composition of the mixture components and their particle sizes.     

水平管道内铝粉爆炸特性的试验研究

为研究铝粉在密闭空间内爆炸特性,降低其爆炸造成的损害,利用自行设计的水平管道式可燃气体-粉尘爆炸装置,在室温下对粒度为6～8μm,9～12μm,15～17μm的铝粉在100～800 g/m3浓度范围内的爆炸特性进行试验研究。结果表明:铝粉在浓度为600 g/m3时,最大爆炸压力和最大压力上升速率最大,爆炸时间最小;铝粉浓度较低时,由于氧气充足,随着铝粉浓度增大,最大爆炸压力和最大压力上升速率增大,爆炸时间减小;当铝粉浓度超过600 g/m3,受到氧气浓度限制,最大爆炸压力和最大压力上升速率随浓度增大而减小,爆炸时间增大;相同浓度的铝粉,粒度越小,最大爆炸压力和最大压力上升速率越大,爆炸时间越小。粒度越小的铝粉,爆炸的可能性和危险性越大。     

Explosions of carbon black and propane hybrid mixtures

Explosions of hybrid mixtures, i.e. mixtures containing more than one combustible phase, are not well understood. Most studies in this area involve mixtures of common dusts and gases, such as coal and methane, or polyethylene and ethylene. The present work focuses on explosions of carbon black particles, i.e. almost pure carbon with a very low content of volatiles: this makes the process of explosion less intense. However, addition of some quantities of combustible gases (here: propane) may sustain combustion processes. Another important issue is the fact that the carbon black particles are smaller in size than most dusts encountered in the process industry. The experiments were carried out in a 20-L explosion vessel and the analysis of the results focuses on the maximum explosion pressures and the maximum rates of pressure rise as a function of carbon black and propane concentrations. In addition, some samples of unburnt dust were collected and analysed with a scanning electron microscope and with thermo-gravimetric analysis.     

When solids meet solids: A glimpse into dust mixture explosions

Mixing an inert solid or a less flammable compound with a combustible dust can be regarded as a direct application of the inherent safety principle of moderation. An experimental investigation was carried out to determine the evolution of the ignition sensitivity and the explosion severity of such various mixtures as a function of their compositions. It demonstrates that the introduction of small amounts of highly combustible powders (such as sulphur or nicotinic acid) to a less flammable dust (such as microcrystalline cellulose or carbon black) can strongly influence the ignition sensitivity as well as the explosion severity.It has notably been shown that the ignition sensitivity of solid/solid mixtures significantly rises up when only 10–5%wt. of highly flammable dust is introduced. Simple models can often be applied to estimate the minimum ignition energy, minimum ignition temperature and minimum explosive concentration of such mixtures. Concerning the dust explosivity, three cases have been studied: mixtures of combustibles dusts without reaction, dusts with reactions between the powders, combustible dusts with inert solid. If the evolution of the maximum explosion pressure can be estimated by using thermodynamic calculations, the maximum rate of pressure rise is more difficult to predict with simple models, and both combustion kinetics and hydrodynamics of the dust clouds should be taken into account. These results were also extended to flammable dust/solid inertant mixture. They clearly show that the concentration of solid inertant at which the ignition is not observed anymore could reach 95%wt. As a consequence, the common recommendation of solid inertant introduction up to 50–80%wt. to prevent dust explosion/ignition should be reconsidered.     

Dust explosion risk moderation for flocculent dusts

The research presented in this paper is focused on dust explosions of coarse and fine flocculent (or fibrous) samples of wood and polyethylene. Hybrid mixtures of fibrous polyethylene and admixed ethylene were also studied. Experimentation was conducted by following standardized test procedures and using standardized apparatus for determination of maximum explosion pressure, size-normalized maximum rate of pressure rise, minimum explosible concentration, minimum ignition energy, and minimum ignition temperature. A general trend was observed of enhanced explosion likelihood and consequence severity with a decrease in material diameter, as well as enhanced consequence severity with admixture of a flammable gas to the combustion atmosphere. The same phenomena are well-established for dusts composed of spherical particles; this highlights the importance of inherently safer design and the principle of moderation in avoiding the generation of fine sizes of flocculent dusts and hybrid mixtures of such materials with flammable gases.In addition to presenting experimental findings, the paper describes phenomenological modelling efforts for the flocculent polyethylene using four geometric equivalence models: radial equivalence, volumetric equivalence, surface area equivalence, and specific surface area equivalence. The surface area equivalence model was found to yield the best estimates of maximum rate of pressure rise for the flocculent polyethylene samples investigated experimentally.     

工业粉尘“二次爆炸”过程研究

开展了工业粉尘“二次爆炸”过程实验室研究工作。对玉米淀粉、小麦粉等粮食粉尘进行了研究，得到了“二次爆炸”发展过程以及最后形成的爆轰波特性，还进一步研究了粉尘层冲击波卷扬过程和分析讨论了粉尘“二次爆炸”过程的影响因素。