玉米淀粉粉尘爆炸特性及火焰传播过程的试验研究?

为了全面地认识玉米淀粉粉尘爆炸的敏感性和爆炸破坏效应,分别采用粉尘云着火温度装置、20 L球粉尘爆炸装置和粉尘云火焰传播装置对玉米淀粉的粉尘云着火温度、爆炸下限质量浓度、爆炸压力、爆炸氧极限浓度以及粉尘云火焰传播过程进行了研究。结果表明:玉米淀粉粉尘云最低着火温度在380~390℃之间;粉尘云爆炸氧极限浓度(体积分数)在10%~11%之间;爆炸下限质量浓度和最大爆炸压力随着化学点火具质量的增加而呈现出不同的变化特征,随着化学点火具质量的增加,玉米淀粉的爆炸下限质量浓度逐渐降低,而玉米淀粉爆炸压力逐渐升高。在不同的粉尘质量浓度条件下,粉尘云火焰传播速度和火焰温度有一定的变化,在粉尘质量浓度为500 g/m3时,火焰传播速度和火焰温度均达到最大值,分别为13.81 m/s和1 107℃。     

锆金属粉尘云最小点火能和最低着火 温度的试验研究

为研究锆金属粉尘云燃烧的基础特性参数,从而为其安全性能提供依据,采用哈特曼管试验系统和最低着火温度测定系统分别对锆金属粉尘云的最小点火能（MIE）和最低着火温度（MIT）开展试验研究。分别研究了锆金属粉尘云质量浓度、点火延迟时间和喷粉压力对MIE的影响,以及粉尘云质量浓度对MIT的影响。结果得出:中位径为33.49 μm的锆金属粉尘云的MIE在1~3 mJ之间;在50~500 g/m³质量浓度范围下,随着质量浓度增大,MIE先减小后增大,在质量浓度为400 g/m³时达到最小;点火延迟时间从10 ms增至180 ms,MIE先减小后增大,在60 ms时达到最小;喷粉压力从0.4 MPa增至1.0 MPa,MIE先减小后增大,在0.6~0.8 MPa间达到最小。该粒度锆金属粉尘云的MIT为210 ℃左右,在一定浓度范围下,MIT随粉尘浓度的增加而减小。     

聚酰胺纤维粉尘的爆炸特性

为研究汽车安全气囊生产过程中产生的聚酰胺纤维粉尘爆炸的危险性,测定聚酰胺纤维粉尘的相关爆炸参数,对粉尘爆炸危险性进行分级。结果表明:聚酰胺纤维粉尘的最小点火能(MIE)为15.8 MJ;粉尘层最低着火温度(MITL)为307℃,粉尘云最低着火温度(MITC)为300℃;在点火头能量为10 k J情况下,样品粉尘爆炸压力最大为0.8 MPa,爆炸指数最大为16.59 MPa·m/s,粉尘爆炸烈度为St1级;聚酰胺纤维粉反应热解特性过程中挥发分初始析出温度(Ts)为228℃,DTG微商峰值温度为429.1℃,最大失质量为每分钟6.99%。     

纤维板砂光粉尘的燃爆特性

以某纤维板生产线的速生杨、马尾松、南方硬杂木的混合砂光粉尘作为研究对象,在分析粉尘粒径及其分布、可挥发分及形貌特征的基础上,采用20 L爆炸球对砂光粉尘进行燃爆实验,探索砂光粉尘的浓度对粉尘燃爆特征的影响,并对爆炸前、后粉尘的热稳定性和特征官能团进行探讨。结果表明,当砂光粉尘质量浓度增加到1 000 g/m3,最大爆炸压力达到最大值0.761 MPa;此后,粉尘浓度的增加反而使砂光粉的最大爆炸压力减小;当粉尘质量浓度增加到1 250 g/m3时,爆炸指数达到最大值17.62 MPa·m/s,且爆炸危险分级为St1(弱爆炸)。实验还采用最小点火能测试系统、热板炉和GodbertGreenwald炉研究了砂光粉尘的燃烧特性,结果表明,粉尘最小点火能为30~100 m J,粉尘层最低着火温度为300℃,粉尘云最低着火温度为420℃。     

梧桐树粉尘爆炸特性研究

以梧桐树粉尘为例,研究了可作为工业粉状炸药添加剂的木粉粉尘的爆炸特性。运用哈特曼管测试了粉尘云的最小点火能,得出样品1#、样品2#和样品3#的最小点火能分别为70、90 m J和150 m J。将响应面法中的Box-Behnken试验设计应用于粉尘爆炸压力的测试,用20 L爆炸球进行试验,并从试验结果中拟合回归方程,由此判断出粉尘浓度对爆炸压力的影响最大,其次是点火能量,再次是粉尘粒径。对爆炸压力的试验条件进行优化,试验测得压力值为0.795 9 MPa,试验值与预测值之间的误差仅为1.28%,证明了该模型非常有效。     

粉尘云最低着火温度的粒径尺度效应

利用粉尘云最低着火温度测试仪研究不同粒径尺寸条件下石松子粉和面粉2种典型可燃性粉尘的粉尘云最低着火温度。结果表明:2种粉尘的粉尘云最低着火温度随粉尘粒径增大逐渐升高;粒径尺寸较小的局部范围内存在拐点,分析认为该现象由较小尺寸粒径之间的静电吸附作用导致。     

几种粉尘层反应动力学参数的研究

研究了两种烟煤和玉米淀粉、石权子粉粉尘层的反应动力学参数。实验是采用热重分析方法在氧浓度分别为0、2％、8％、20％、50％和100％及层流条件下进行的．并用气相色谱在不同的温度范田内对粉样的气相成分进行了分析，依据实验结果求出上述4种粉尘的氧化、热解动力学参数并对粉尘层氧化某些机理作了描述。     

膨化硝铵炸药粉尘爆炸性的初步实验研究

膨化硝铵炸药是一种常见的工业炸药,该文通过20L爆炸球对其粉尘爆炸的危险性进行了试验研究,并和玉米淀粉粉尘进行了比较。研究结果表明,膨化硝铵炸药发生粉尘爆炸的可能性很小,在50～1100g／m^3的浓度范围均未发生粉尘爆炸;玉米淀粉有着粉尘爆炸的危险。所得结果为它们的生产及使用安全提供了必要的参考。     

基于峰值检测的电火花能量测量方法

目的:针对示波法测量火花能量存在测量复杂、成本高昂等问题,提出了一种基于峰值检测的可集成、低成本的测量方法。方法:依据传统的电火花放电曲线符合衰减的正弦周期性函数,故可利用峰值检测电路检测多个峰值点,反向还原电火花放电曲线过程,并积分求取点火能量。通过Multisim、MATLAB仿真得出峰值检测电路能够很好地跟随与捕获峰值电压。结果:在粉尘云最小点火能量测量平台的基础上搭建电路测量系统,设计实验进行验证,表明该方法用于测量火花能量具有较好的效果。结论:此方法的测量结果与示波法测量结果对比,误差在34%以内。     

几种粉尘层反应动力学参数的研究

研究了两种烟煤和玉米淀粉，石粉子粉粉尘层的反应动力学参数，实实验是采用热重分析方法在氧浓度分别为０．２％、８％、２０％、５０％和１００％及层流条件下进行的。     

Investigation of lag on ignition of coal dust clouds under varied experimental conditions

Lag on ignition (LOI) of coal dust cloud greatly influences the initiation and propagation of coal dust explosion. This paper investigates the effects of coal dust particle size, dust concentration, ignition temperature, and dust dispersion pressure on LOI of coal dust clouds using Godbert-Greenwald furnace along with a high-speed camera. LOI of coal dust cloud significantly decreased by 1/13 times from 959 to 77 ms with increase in the ignition temperature from 600 to 1000 °C, demonstrating greatest influence of ignition temperature on LOI. LOI increased by 60% with increase in dust concentration from 500 to 4000 g/m³. Optimum dust dispersion pressure at which LOI was found minimum is determined 70 kPa. Empirical relations are established between LOI of coal dust cloud and particle size, ignition temperature, dust concentration, and dispersion pressure. The results are analysed in terms of the occurring physical processes, which led to a better understanding of the variation of LOI, ignition behavior, and explosion propagation of coal dust clouds at varied experimental conditions.     

粒径对煤粉云最低着火温度特性的影响

为了研究粒径对煤粉云最低着火温度特性的影响,采用粉尘云最低着火温度测试装置测试了不同粒径下煤粉云的最低着火温度,并结合ReaxFF分子动力学对其反应机理进行了微观层面的探讨。结果表明:当煤粉中位径在34 μm时,煤粉云的最佳着火质量浓度为750 g/m³,最低着火温度为550 ℃;随着煤粉粒径的增加,煤粉云最低着火温度逐渐增大,当煤粉中位径达到124 μm,煤粉云最低着火温度上升至650 ℃。通过ReaxFF分子动力学对煤粉热解过程的计算结果表明:随着反应的进行,大分子煤结构逐步分解,芳香环、C—C键、C—O键和C—H键等断裂,产生更小的分子结构,其中,H₂、H₂O、CO₂和CH₂O等小分子产生的数量逐渐增多;H·自由基和OH·自由基在反应初期有明显的数量变化,且其含量对于最终稳定产物有重要影响。     

An investigation of iron sulphide dust minimum ignition temperatures

An investigation of the ignition behaviour of iron sulphide dusts has been undertaken. Commercial samples of FeS and FeS(2) and mine samples of pyrrhotite and pyrite were tested for minimum ignition temperature (MIT) using a device known as the BAM oven. The mine samples were found to undergo a decrease in MIT as the mass mean particle diameter became smaller. Using available theoretical treatments, this experimental observation was interpreted as providing further evidence of the importance of heterogeneous combustion in the ignition of iron sulphide dusts. A dense cloud state was proven for the experimental apparatus used, and an alternate criterion for the boundary between a dilute and a dense dust cloud was proposed in terms of the number of dust particles present in the cloud.     

Measurement of minimum ignition energies of dust clouds in the <1mJ region

The lower energy limit of current standard test apparatus for determining the minimum ignition energy (MIE) of dust clouds is in the range of 1-3mJ. This is a quite severe limitation because many dusts ignite readily at this energy level. A new spark generator, capable of producing synchronised sparks of very low energies and with an integrated system for measurement of spark energy, has therefore been developed and employed to a number of easily ignitable dusts. Before testing the MIE of dust clouds, it was considered essential to calibrate the new spark generator against a gas of known MIE. For this purpose, a mixture of propane and air was selected. However, a comprehensive literature review revealed that the reported MIEs of this gas mixture vary significantly, depending on the spark discharge characteristics, including discharge duration. When taking these factors into account, it was concluded that the new spark generator yielded reasonable results for propane/air. Applying the new spark generator to explosive dust clouds showed that a number of dusts do in fact have MIEs that are one to two orders of magnitude lower than 1mJ. The new spark generator may therefore offer a basis for developing a standard test apparatus in the low-energy region. When using a method of triggering the spark by the explosive dust cloud itself, which probably is a more industrially relevant process than synchronisation between the dust dispersion and sparkover, somewhat higher MIEs were found compared to those determined when using synchronised sparks. However, even with this method of spark triggering, MIEs below 1mJ were found.     

MIKE 3 versus HARTMANN apparatus: comparison of measured minimum ignition energy (MIE)

In this study, MIE values measured with two different explosion tubes, HARTMANN and MIKE 3, are compared. Generally, MIKE 3 apparatus provides MIE results, which are equal or lower to those measured with the HARTMANN apparatus; this is particularly true for the energy ranges between 1 and 10mJ and higher than 100mJ. Differences observed can modify samples classification according to their sensitivity to electrostatic ignition sources. Nevertheless, ignition of a dust cloud by an electrostatic discharge is complex, and implies a different mechanism from that occurring during MIE tests. Thus, it seems difficult to synchronise dust dispersion and spark triggering to obtain optimal concentration in the spark area. Moreover, spark characteristics such as duration or energy feeding rate of spark cannot reproduce exactly industrial-world ones. On this point, it is not possible to conclude if characteristics of MIKE 3 electric circuit, e.g., resistance and inductance, are more relevant than HARTMANN circuit ones.     

石松子粉最小点火能试验研究

采用1．2L哈特曼管最小点火能测试装置,研究了中位径为32μm的石松子粉的最小点火能量随粉尘浓度、点火延时以及喷粉压力之间的变化规律。试验结果表明：在环境温度为（25±5）℃,环境湿度为30％±5％的条件下,石松子粉的最佳着火浓度750g／m3,最佳点火延时为90脚,最佳喷粉压力为0．8MPa,此时石松子粉的最小点火能达到极小值。在相同的实验条件下有电感的点火方式比无电感的点火方式所需的能量要小。在有电感存在的情况下,石松子粉的最小点火能为10mJ;在无电感存在的情况下,石松子粉的最小点火能为15mJ,说明石松子粉对电火花较敏感。     

Research on law and mechanism of dust explosion in bag type dust collector

The bag type dust collector will accumulate dust during long-term operation, and the high temperature during operation will cause dust explosion. In this paper, with the dust removal system involved in the “8·2” Kunshan dust explosion accident taken as the research background, the minimum ignition temperature and lower explosion limit experiments are carried out on aluminum powder with different particle sizes (10–60 μm) by using the lowest ignition temperature test device and the 20 L near-spherical explosive device. The dust concentration distribution and temperature field in the bag type dust collector are analyzed through the CFD-FLUENT software. Through the analysis of the experimental results, it is found that when the particle size of aluminum powder is 19 μm, the minimum ignition temperature is 585 °C, and the lower explosion limit of concentration is 0.04 kg/m³. The simulation results indicate that the dust particles gather in the dust collecting bucket, and the aluminothermic reaction occurs in the dust collecting bucket. The temperature of the upper and right parts in the dust collecting bucket is above 600 °C, which exceeds the minimum ignition temperature. At the interface between the dust hopper and the dust collecting bucket, the concentration of aluminum powder reaches 0.126 kg/m³, which exceeds the lower explosion limit of aluminum powder.