硫磺粉尘燃爆危险性研究

为预防硫磺粉尘的燃爆危险性,测试了硫磺的自燃温度、自热特性、热稳定性、最小点火能、爆炸下限质量浓度、爆炸压力和爆炸指数,根据实验结果对硫磺粉尘危险性做了分级。结果表明,随着粒径的减小,硫磺粉尘的自燃温度、最小点火能和爆炸下限质量浓度相应降低,爆炸压力和爆炸指数则升高;70 μm以下粒径的硫磺粉尘的自燃温度（AIT）为220 ℃,最小点火能（MIE）为0.14 mJ,爆炸下限质量浓度（MEC）为17.5 g/m3,最大爆炸压力（pmax）为1.15 MPa,最大爆炸指数（Kmax）为39.87 MPa·m/s,因此燃爆危险性最高;450 μm以下粒径的硫磺粉尘爆炸危险性等级均为St3级。     

HDPE粉尘一次及二次爆炸特性研究

为研究高密度聚乙烯(HDPE)粉尘的爆炸特性,采用20 L球粉尘爆炸装置,对5种不同粒径的HDPE粉尘进行实验,分析粉尘质量浓度、喷粉压力和粒径大小对HDPE粉尘一次爆炸与二次爆炸最大爆炸压力及其上升速率的影响,并对两者进行了对比分析.结果表明:随着粉尘质量浓度从225 g·m-3增加到375 g·m-3,HDPE粉尘一次和二次爆炸的最大爆炸压力及其上升速率均先增大后减小;随着粉尘粒径从18μm增加到75μm,HDPE粉尘一次和二次爆炸的最大爆炸压力及其上升速率同样先增大后减小;随着喷粉压力从0.5 MPa增加到3.0 MPa,HDPE粉尘一次和二次爆炸的最大爆炸压力及其上升速率均先降低后上升;HDPE粉尘二次爆炸最大爆炸压力及其上升速率与一次爆炸时相比均较小.     

干燥对褐煤爆炸危险性的实验研究

为探究干燥前后褐煤的爆炸危险性,基于粉尘爆炸机理,通过粒度分析和爆炸性测定实验,分析了干燥前后褐煤粒径分布变化、扬尘特性及爆炸危险性变化.结果表明,干燥褐煤大粒径颗粒频数减小,小粒径颗粒频数增加,粒径变小,扬尘量增加;干燥褐煤最小点燃能量、粉尘云/层最低着火温度较干燥前褐煤都有所降低.干燥褐煤较原煤更易扬尘达到爆炸极限浓度,且更易发生着火燃烧爆炸,干燥褐煤爆炸敏感性和危险性都增加.     

乙烯/聚乙烯两相体系爆炸特性

基于改进的20 L球形爆炸装置,实验测量了乙烯/聚乙烯两相体系爆炸特性参数,系统地分析了两相体系爆炸下限和爆炸强度变化规律,并对比分析了乙烯、聚乙烯和乙烯/聚乙烯3种体系爆炸强度之间的关系。结果表明：乙烯诱导聚乙烯最小爆炸浓度显著降低,低于爆炸下限的乙烯气体与低于最小爆炸浓度的聚乙烯混合后仍具有爆炸危险性。向不同浓度的聚乙烯粉尘中添加乙烯后,爆炸压力p_ex和压力上升速率（dp/dt）_ex均显著提高,但增幅随粉尘浓度的增大而减小。乙烯/聚乙烯两相体系最大爆炸压力p_max和爆炸指数K_st均随乙烯浓度的增大而增大,但不同乙烯浓度下的两相体系最大爆炸压力p_max和爆炸指数K_st均大于单相聚乙烯粉尘,小于单相乙烯气体。     

可燃性气体对PE粉体静电放电点火的影响

运用标准粉尘爆炸测试装置Hartmann管分别测试了聚乙烯(PE)粗料和经过筛分的PE粉体的最小点火能量,比较了PE粉体和可燃性气体共存时(即杂混合物)的最小点火能量与不同形式的静电放电能量.当PE粉体粒径小于2 mm时,随着粒径的增大,可燃性气体对杂混合物最小点火能量的影响也越大.但可燃性气体对PE粉体静电点火的影响变小.当可燃性气体浓度低于10%爆炸下限时,对未经过筛分的原始粉体,各种形式的静电均无法将其点燃;对粒径小于0.5 mm的PE粉体,可以排除电晕放电、刷形放电和堆表面放电作为点火源的可能性:对粒径小于75μm的PE粉体,堆表面放电、火花放电和传播型刷形放电均是可能的点火源.     

粉末涂料爆炸特性研究

为探究粉尘浓度对不同粉末最大爆炸压力、最小着火能量、爆炸下限等爆炸参数的影响,在1. 2 L Hartmann管实验装置中开展了3类粉末涂料爆炸特性实验研究,同时结合扫描电镜和粒径分析了不同粉末涂料爆炸的危险性。结果表明:黑水纹样品粉尘爆炸危险性最强,最大爆炸压力达0. 742 MPa,爆炸下限为25 g/m³,最小着火能量在18～28 mJ范围内;黑砂纹样品粉尘爆炸危险性相对较低,爆炸下限为75 g/m³,其中样品1最大爆炸压力为0. 604 MPa,最小着火能量于35～45 mJ范围内,样品2最大爆炸压力为0. 643 MPa,最小着火能量于91～101 mJ范围内。3类粉末涂料爆炸最危险浓度比较接近,黑水纹样品、黑砂纹样品粉尘爆炸的最危险浓度为800 g/m³,闪银样品为600 g/m³。     

不同粒度谷壳糠粉的燃烧特性

为了探索谷壳糠粉的燃烧特性,基于粉尘层和粉尘云实验研究了粒径对其最低着火温度的影响,采用哈特曼管和锥形量热仪测试了不同粒径谷壳糠粉的爆炸下限和热释放性能,利用热重/差式扫描量热仪系统地研究其燃烧特性和燃烧动力学。结果表明：随着谷壳糠粉粒径的减小,其最低着火温度（MIT）和爆炸下限浓度（LEL）降低,但最大爆炸压力P和爆炸压力上升速率均增大。其中粒径为80～96μm样品的爆炸压力为0.9MPa,其粉尘层（5mm及10mm）和粉尘云最低着火温度分别为130℃和430℃,燃烧特性指数S_N达到3.82×10^-7,较粒径为180～1250μm样品提高了57.2%;在307s出现最大释热峰,且最大释热峰值强度增加至62kJ/m²,对应热解过程的反应活化能由35.35kJ/mol（180～1250μm样品）增大至51.15kJ/mol,表明其燃烧过程随粒径的减小由扩散控制转变为动力学控制过程。     

镁粉爆炸特性的实验研究

镁粉具有爆炸的危险性。采用20L球形爆炸实验装置,研究了镁粉爆炸过程中镁粉的浓度、镁粉粒径对最大爆炸压力、最大压力上升速率的影响;提出了预防镁粉爆炸、降低爆炸的安全措施。实验结果表明,随着镁粉浓度的增加,爆炸的危害性越大,当浓度增加到一定程度时,爆炸压力和压力上升速率达到最大值,此时浓度再增加,爆炸压力和压力上升速率将逐渐减小,爆炸的危害性减小;此外镁粉粒径越小,爆炸危害性越大。     

乙烯/聚乙烯两相体系爆炸特性

基于改进的20 L球形爆炸装置,实验测量了乙烯/聚乙烯两相体系爆炸特性参数,系统地分析了两相体系爆炸下限和爆炸强度变化规律,并对比分析了乙烯、聚乙烯和乙烯/聚乙烯3种体系爆炸强度之间的关系。结果表明:乙烯诱导聚乙烯最小爆炸浓度显著降低,低于爆炸下限的乙烯气体与低于最小爆炸浓度的聚乙烯混合后仍具有爆炸危险性。向不同浓度的聚乙烯粉尘中添加乙烯后,爆炸压力pex和压力上升速率(dp/dt)ex均显著提高,但增幅随粉尘浓度的增大而减小。乙烯/聚乙烯两相体系最大爆炸压力pmax和爆炸指数Kst均随乙烯浓度的增大而增大,但不同乙烯浓度下的两相体系最大爆炸压力pmax和爆炸指数Kst均大于单相聚乙烯粉尘,小于单相乙烯气体。     

聚磷酸铵抑制PMMA粉尘爆炸特性研究

为研究聚磷酸铵(APP)对聚甲基丙烯酸甲酯(PMMA)粉尘爆炸的抑制特性,从最大爆炸压力P_ex、最大爆炸压力上升速率(dP/dt)_ex、最小点火能量(MIE)和最小点火温度(MIT)等多方面分析了APP对PMMA粉尘爆炸特性的影响。结果表明,APP可有效降低PMMA粉尘最大爆炸压力和最大爆炸压力上升速率,并延迟最大爆炸压力峰值到达时间;对于不同浓度PMMA粉尘的MIE,APP均有显著的抑制效果,且存在临界抑制浓度配比1∶1,在该浓度配比条件下PMMA粉尘很难通过静电点火;对于不同浓度PMMA粉尘的MIT,APP同样均具有一定抑制作用,且相同浓度配比条件下,抑制作用随PMMA浓度的增大而增大。此外,结合APP和PMMA热特性及红外光谱分析结果,分析了APP抑制PMMA粉尘爆炸机理。     

Study of Ignition Temperature of a Polyethylene Dust Cloud

Dust explosion hazard exists in plants and facilities wherever combustible dusts are handled. The minimum ignition temperature of dust clouds is an important factor requiring special attention for the design of any explosion preventive measures. The present paper is confined to a study of the minimum ignition temperature of the cloud of polyethylene, an organic dust. This parameter was determined using the Godbert–Greenwald furnace apparatus for different particle sizes and dust concentrations. Some preliminary experiments were carried out for determination of minimum explosive concentrations of polyethylene dust to specify experimental conditions for determination of minimum ignition temperature. The experimental results, particularly variation of minimum ignition temperature with particle size and dust concentration, have been explained on the basis of a two-stage ignition involving devolatilization of solid particles into gaseous intermediates and homogeneous combustion of these gaseous components. A model was also developed for determining the minimum ignition temperature of polyethylene dust simulating conditions in the test furnace and this will be presented in a separate paper.     

铝粉粒度对乳化炸药能量输出特性及热安定性的影响

为了研究铝粉粒度对乳化炸药水下爆炸能量输出的影响,在相同乳化炸药中分别添加3种不同粒度的铝粉制得含铝乳化炸药。利用水下爆炸实验,获得冲击波压力时程曲线,经分析计算得到峰值压力、冲击波冲量、比冲击波能、比气泡能、总能量等水下爆炸能量参数。并运用DSC-TG联用技术测试添加不同粒度铝粉的乳化炸药在不同升温速率下的热安定性。结果表明：铝粉粒度对乳化炸药水下爆炸的能量有较大的影响,添加了中粒度（平均粒度为177.2 μm）铝粉的乳化炸药各能量参数均达到最大值,而3组样品的热安定性则随着铝粉粒度的减小而降低,活化能的最大降幅达3.7%。     

Hot-surface ignition temperatures of dust layers

Minimum dust layer ignition temperatures on a hot surface were determined for several dusts, using a test procedure recommended by the National Academy of Sciences. The dusts included coal, three oil shales, lycopodium spores, corn starch, grain and brass powder. For a few of the dusts the effects of particle size and layer thickness on the minimum ignition temperatures were examined. Test results were repeatable and reliable for the fuels, the lycopodium and the brass powder. The minimum hot-surface ignition temperatures of 12.7-mm thick layers of these dusts ranged from 160°C for brass to 290°C for 20-gal ton⁻¹ oil shale. Flaming combustion was observed only with the brass powder. The minimum ignition temperatures decreased with thicker layers and with smaller particle sizes. Some difficulties were encountered with the corn starch and grain dusts. During heating, the starch charred and expanded; the grain dust swelled and distorted. The test was found acceptable for the purpose of determining the minimum layer ignition temperature of a variety of dusts. To prevent fire hazards due to smoldering or flaming dust layers the temperatures of surfaces on which combustible dusts accumulate should be lower than the minimum hot-surface ignition temperatures of the dusts.     

Experimental investigation of the suppression effects of ammonium polyphosphate on explosion characteristics of unsaturated polyester resin dust

The suppression effects of Ammonium Polyphosphate (APP) with different mass fractions on the maximum explosion pressure (P_max), the explosibility index (K_st), the minimum ignition energy (MIE) and the minimum ignition temperature (MIT) of unsaturated polyester resin (UPR) dust were studied. Results indicated that the explosion severity and the ignition sensitivity of UPR dust decreased gradually when the mass fractions of APP increased. There existed a minimum inerting concentration (MIC), and the explosion of UPR dust could be suppressed completely by 60 wt% APP. Moreover, APP had a great inhibiting effect on the MIE of UPR dust cloud. The calculated MIE of UPR dust cloud increased from 10 mJ to 998 mJ when the mass fractions of APP increased to 30 wt%. Furthermore, the MIT of UPR dust cloud increased with the increase of the mass fractions of APP. When the mass fraction of APP increased to 80 wt%, the MIT increased by 290°C. The suppression mechanism of APP was studied according to thermogravimetry (TG) and differential scanning calorimetry (DSC) tests. Thermal analysis results showed that the addition of APP could increase the thermal stability of UPR. The suppression mechanism was reflected on the consumption of H and OH radicals.     

Minimum ignition temperature of polyethylene dust: a theoretical model

Dust explosion hazard exists in plants and facilities handling combustible dusts. The minimum ignition temperature of dust clouds is an important parameter requiring special attention to designing the explosion preventive measures. This paper presents a model developed for determining the minimum ignition temperature for an organic dust cloud, polyethylene, simulating the conditions in the Godbert-Greenwald furnace. The model correlates the particle size, as well as the dust concentration with the minimum ignition temperature. It is based on the two-stage oxidation mechanism involving devolatilization/decomposition of the solid particle and homogeneous oxidation of volatile combustible products. In the case of polyethylene, the main combustible gas responsible for ignition and flame propagation has been confirmed to be butylene. The results of the computations were compared with the experimental values and those predicted by Mitsui and Tanaka. The predicted values by the model developed are in close agreement with the experimental data which confirm the proposed ignition mechanism. The model can be used for the prediction of minimum ignition temperature of organic dusts having an autoignition mechanism similar to polyethylene dust. © 1997 John Wiley & Sons, Ltd.     

干燥褐煤的自燃与爆炸特性试验研究

为抑制褐煤堆放时发生自燃与煤粉爆炸,利用自燃装置试验台和煤粉爆炸试验台,对褐煤及其干燥到不同水分的干燥煤进行试验研究,分析其自燃特性和爆炸特性。结果表明,对于自燃特性而言,褐煤水分减少10%,耗氧速度增加约0.17%/min,粒径减小一个等级,耗氧速度增加约0.11%/min;对于爆炸特性而言,褐煤水分减少5%,平均煤粉爆炸下限质量浓度约降低0.015 kg/m~3,温度每升高10℃,平均煤粉爆炸下限质量浓度降低约0.03 kg/m~3;总体而言,随着干燥程度的加深,褐煤自燃、爆炸特性均增强,危险性增加。