Detonation characteristics of ammonium nitrate and activated carbon mixtures

To better understand the detonation characteristics of ammonium nitrate (AN) and activated carbon (AC) mixtures, steel tube tests were carried out for AN/AC mixtures of various compositions and different forms of AN (powdered, prilled, phase stabilized and granular), and the detonation velocity was measured. The powdered AN/AC mixtures gave higher detonation velocities than the other AN forms. For all the AN/AC mixtures, the experimentally observed detonation velocities at each loading density were far below the theoretically predicted values calculated by the CHEETAH code based on thermohydrodynamics, exhibiting so-called non-ideal detonation. The lowest detonation velocity of powdered AN/AC mixtures was obtained as D=1.25 km/s for an AC content of 0.1 wt%. This was considered to be close to the critical condition for stable detonation.     

农用改性硝酸铵拒爆机理及工业化可行性研究

对农用硝铵作改性处理,通过筛选和优化实验确定了改性硝酸铵配方。结果表明,当硝酸铵中添加3%的改性剂GXJ1,10%的改性剂GXJ2时,产品在1mm铁皮管约束下的雷管感度试验条件下具有拒爆特性。改性硝酸铵总养分与普通硝酸铵相当,并且颗粒强度高,不易粉化、结块和吸潮,具有优良的肥料品质。同时还利用X射线衍射分析、扫描电子显微镜分析对改性硝铵的拒爆机理作初步探讨。最终,建立了改性硝酸铵的脱水性能、流动性能、凝固性能、颗粒强度的评价方法,并进行了工业化可行性研究。     

废弃火药在工业炸药中的再利用研究进展

介绍了废弃发射药及固体推进剂在工业炸药中的资源化利用技术,概述了含火药的粉状炸药、浆状炸药、乳化炸药、铵油炸药及灌注型炸药的爆轰性能,分析了各类炸药的工艺生产、使用及安全环保等特点。粉碎后的火药颗粒(Φ≤5 mm)可用于制备粉状炸药,也可利用现有的工业炸药生产工艺,将火药作为敏化剂加入浆状炸药、乳化炸药/乳化基质中,或将大颗粒火药直接与铵油炸药混合。这些方法工艺简单,且火药的加入有利于提高炸药的爆轰性能。尤其是含火药颗粒的灌注炸药生产工艺更简单、安全性更高,避免了火药粉碎工艺,废弃火药的再利用率高,而且炸药的爆轰性能优良,爆速大于6000 m/s,用作震源药柱或露天炸药等具有良好的应用前景。国内已成功地将废弃发射药再利用于工业炸药中,取得了良好的效益。借鉴国内外的研究成果,结合工业炸药的发展趋势,目前应重点进行废弃复合固体推进剂的应用研究。     

Effect of urea on detonation characteristics and thermal stability of ammonium nitrate

A study has examined the effect of urea on the thermal stability and detonation characteristics of ammonium nitrate (AN). The thermal decomposition temperature and surface morphology of samples were investigated by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). For further research on the thermal sensitivity and shock sensitivity of the samples, the Koenen test and UN gap test were conducted. The results indicate that urea can substantially increase the thermal stability of AN (the greatest exothermic peak is increased by more than 100 °C) and reduce the thermal sensitivity of AN. However, AN-50wt. % urea mixtures can still produce a steady detonation in the UN gap test. Urea cannot reduce the ability to propagate a detonation. Possible explanations for these results are discussed.     

提高铵梯炸药生产安全性的技术途径

本采用粗制TNT代替军工TNT应用于工业炸药中,不仅可减少环境的污染,而且可提高生产安全性。实验证明由粗制TNT制成的炸药,其性能可满足使用要求。     

Methane–air detonation experiments at NIOSH Lake Lynn Laboratory

The methane–air detonation experiments are performed to characterize high pressure explosion processes that may occur in sealed areas of underground coal mines. The detonation tube used for these studies is 73 m long, 105 cm internal diameter, and closed at one end. The test gas is 97.5% methane with about 1.5% ethane, and the methane–air test mixtures varied between 4% and 19% methane by volume. Detonations were successfully initiated for mixtures containing between 5.3% and 15.5% methane. The detonations propagated with an average velocity between 1512 and 1863 m/s. Average overpressures recorded behind the first shock pressure peak varied between 1.2 and 1.7 MPa. The measured detonation velocities and pressures are close to their corresponding theoretical Chapman-Jouguet (CJ) detonation velocity (D_CJ) and detonation pressure (P_CJ). Outside of these detonability limits, failed detonations produced decaying detached shocks and flames propagating with velocities of approximately 1/2 D_CJ. Cell patterns on smokefoils during detonations were very irregular and showed secondary cell structures inside primary cells. The measured width of primary cells varied between 20 cm near the stoichiometry and 105 cm (tube diameter) near the limits. The largest detonation cell (105 cm wide and 170 cm long) was recorded for the mixture containing 15.3% methane.     

HNIW/HTPB传爆药的制备及性能研究

以HNIW为高能填料,以HTPB为粘结剂,采用真空浇注法制备了HNIW/HTPB传爆药。为研究HNIW基浇注型传爆药的爆炸特性,通过实验制备了HNIW/HTPB传爆药,并对其撞击感度、临界直径和爆速等性能进行了分析研究。结果表明,HNIW/HTPB传爆药对撞击作用较钝感,当HTPB的含量为12%时,其特性落高h50为51.68cm,临界直径小于0.6mm,它的实测爆速为8248m/s,接近其理论爆速8320m/s,且HNIW/HTPB传爆药各组分之间具有良好的相容性,因此该传爆药具有良好的安全性能和传爆性能,适合于微尺寸装药,从而具有广阔的应用前景。     

Investigation of ammonium nitrate based emulsion ignition characteristic

This paper presents an analysis of the observed ignition behaviors of ammonium nitrate (AN) and emulsion explosives (EE). Pure AN and EE locally ignited by a heat source do not undergo sustained combustion when the pressure is lower than some threshold value usually called the Minimum Burning Pressure (MBP). A reason for pure AN's and EE's incapable of burning was suggested, and the roles of sample water, inorganic salts, oil phase, and sensitizer were discussed. Accelerating rate calorimeter (ARC) was used to study the thermal stability of EE and AN. The results also showed that MBP is of vital importance and useful for the manufacture and application of AN and EE in terms of accident prevention.     

TA-FTIR/MS用于硝酸铵及其混合物的热化学行为研究

为评价物料混合对危险化学品热化学行为的影响,采用热分析-红外/质谱联用技术(TA-FTIR/MS)研究硝酸铵、柠檬酸和蔗糖的混合物的热化学行为。通过对硝酸铵及其混合物的分解温度和分解过程中逸出气体的分析,发现硝酸铵、柠檬酸和蔗糖的混合物热分解温度分别降低至135℃和153℃,而硝酸铵与甲基纤维素的混合物分解温度与硝酸铵基本相同为201℃,且各混合体系的气相分解产物均有氮氧化物(NOX),H2O和CO2。结果表明,混合物受热后其中的硝酸铵首先分解为硝酸和氨气;酸性物质和还原性物质由于对硝酸的分解反应有催化作用,使得混合物的热稳定性下降。     

硝酸及氯离子对高温硝酸铵水溶液热危险性的影响研究

国内外学者对硝酸铵的危险性进行了大量的研究,而对其水溶液的危险性至今开展不多。笔者采用差示扫描量热仪(DSC)及全自动反应量热仪(RC1e)对高温状态下的硝酸铵水溶液的热分解危险性、杂质离子对其稳定性的影响进行了研究。纯硝酸铵和90%硝酸铵水溶液的DSC实验表明,90%硝酸铵溶液和分析纯硝酸铵具有相似的热爆炸危险;90%硝酸铵水溶液在140~180℃之间的RC1e试验表明:硝酸或氯离子单独存在时,对硝酸铵分解都有不同程度的抑制作用,而同时存在时则大大降低体系的热稳定性。该结果对保障硝酸铵在生产、使用过程中的安全具有重要的参考价值。     

无机酸对硝酸铵热稳定性影响的研究

为了研究硫酸、盐酸两种无机酸对含能材料硝酸铵热稳定性的影响,使用绝热加速量热仪ARC和微量量热仪C80,对纯硝酸铵及硝酸铵和硫酸、盐酸的混合物进行了热分析实验并研究各种样品在恒温以及升温条件下的吸、放热特性。根据化学反应动力学和热力学理论,确定了硝酸铵及其与无机酸的混合物发生放热分解反应的反应动力学参数和热力学参数。基于Semenov热爆炸模型,计算并比较了各样品标准包装的自加速分解反应温度。     

Estimation of the liability to detonating of prilled ammonium nitrate fertiliser grade

The statistical analysis of the results of testing liability to detonation of coated and uncoated prilled ammonium nitrate was performed. The correlation between the crushing of the lead cylinders as a result of the so-called 4″ tube test and the chemical as well as the physical properties of ammonium nitrate were determined. The results demonstrated that the liability to detonation of ammonium nitrate may be estimated by use of mathematical equations, which employ easily obtainable experimental values relating to the chemical composition and physical properties of the tested fertilisers.     

Detonation flows in aluminium particle gas suspensions,inhomogeneous in concentrations

A physical and mathematical model of the reduced kinetics is presented describing heterogeneous detonation in suspensions non-uniform in particle concentration. The model is based on the heterogeneous media approaches, semi-empirical laws of ignition and combustion, and data on the dependence of the detonation velocity on particle concentration. Formation of suboxides and incomplete combustion of aluminum are taken into account integrally. The dependence of the heat release of chemical reactions and the fraction of unburnt particles on the initial composition is determined from the solution of the stationary problem of the structure of the detonation wave. In the calculations of unsteady detonation flows, it is supposed to solve an additional equation for the spatial distribution of initial concentrations. The problems of initiation and development of cellular detonation in flat channels in suspensions of micron-sized aluminum particles are studied. Dependences of the cell size on particle concentration in uniform suspensions are determined. The flow patterns of cellular structures, the forms of the leading front, and the propagation velocities in channels with longitudinal or transversal gradients of particle concentration are analyzed.     

基于两相流模型数值研究可燃颗粒燃烧爆轰的特性

粉尘爆炸是工业爆炸灾害的重要形式。建立可燃颗粒非均相系统的燃烧爆轰模型,基于Eulerian-Eulerian数值描述方法,采取有限差分方法编制非均相系统燃烧和爆轰发展的数值模拟程序,对封闭空间内两相非定常爆轰过程进行研究。数值分析可燃颗粒尺度、颗粒浓度对非均相系统燃烧、爆轰特性的影响。结果表明:在一定的范围内,当可燃颗粒的体积分数为10%,粒径0.5mm时,流场的燃烧爆轰效应最强。即10.6ms时刻,流场压力值达到28MPa,温度高达2600K,颗粒燃烧效率最高。     

天然气水合物水力提升中继舱舱体沉积安全性分析

针对天然气水合物水力提升过程中中继舱部件的沉积安全性问题,为了避免中继舱因沉积过多而导致整个提升系统的瘫痪,利用流场模拟软件CFD,分析了不同结构对中继舱内部流场的影响,对比了正方体、球体和圆柱体3种不同中继舱结构下的颗粒沉积情况、内部流速分布、粗细颗粒以及海水体积分数分布情况,得出圆柱体结构的安全性要优于另外两种结构。研究了圆柱体结构在不同工况下的沉积情况与安全性。结果表明:增加粗颗粒浓度,粗颗粒直径以及粗颗粒的密度都会导致中继舱沉积厚度增加,安全性降低,而增加进口速度则会导致中继舱沉积厚度减小,安全性有所提高。     

阜山金矿进回风巷粉尘孔粒径分布及其分形特征

为探究金属矿井下粉尘孔粒径特征,以阜山金矿为例,系统研究其进风巷粉尘(IAD)、回风巷粉尘(RAD)的孔粒径分布(PSD)情况.首先,利用激光粒度分析仪与扫描电子显微镜(SEM)、低温液氮吸附仪分别测试粉尘粒径与孔参数,然后利用分形理论计算并分析其粒度分形维数与孔分形维数.结果 表明:RAD粒径比IAD粒径小,两者最可...     

Analysis of the experimental results of the initiation of detonation in short tubes with kerosene–oxidizer mixtures

The paper describes the experimental investigation of detonation initiation in a mixture of kerosene–oxidant in a short test tube. Various mixtures of oxygen and nitrogen were used as an oxidant, from pure oxygen to the composition of air. The goal of the study was to determine the minimum diameter of the tube and the minimum level of energy needed for the direct initiation of detonation. As a result of the measurements the pressure courses were obtained for two kinds of cases: with and without (only shock waves) of fuel injection. The results of both kinds of measurements were compared, providing information about the initiation of detonation in a fuel–oxidizer mixture. Brief analyses of the results for different initiators and different oxidizers were performed and compared with the shock wave and Chapman–Jouget velocity.     

Filtration Properties of Nonwovens

Abstract

This paper presents the results and conclusions from experimental investigations concerning filtration properties of nonwovens. The needled nonwovens were made from polyester fibres (PTE) with average fibre diameter 12 µm and polypropylene fibres (PP) with average fibre diameter 32 μm. Nonwovens were produced out of each of those fibres or out of a mixture of polyester and polypropylene fibres. This paper also presents investigations of nonwoven fabric made of polypropylene fibres (PP) with average fibre diameter 2.6 μm, which was formed according to melt-blown technology. Oil mist, as challenge aerosol, was used to evaluate the performance of filter media at various aerosol velocities. The average oil mist test aerosol particle diameter was 0.3 μm. Filter penetration was measured at oil mist concentration 0.24 g/m³.     

HMX粒度、粒度级配对混合传爆药性能影响的研究

通过喷射方法把主体炸药 HMX重结晶后 ,将其制成粗细不同的几种粒度药粉 ,并按粗细不同比例进行级配 ,随后采用 SSGT和爆速测试 ,研究了不同粒度及粒度级配对其混合传爆药冲击波感度和爆速的影响规律 ,并对其结果进行了理论分析。由于实验条件的限制 ,还不能达到按要求控制条件以细化出要求的各种粒径 ,所以实验所选的几种级配粒度是随机的 ,因而具有代表性。     

Droplets behaviors of flashing jet in accidental release of superheated liquid

Structural failure of an industrial superheated liquid tank or pipe usually results in the flashing jet consisting of a mixture of massive droplets and vapor due to the violent phase transition. In this work, experiments on small-scale releases were carried out with a 20 L storage tank to investigate the droplets behaviors of flashing jets after accidental releases of superheated liquid. Distribution of droplets axial, radial and vertical velocities, as well as droplets diameter along the centreline of flashing jet, were acquired employing a Phase Doppler Anemometry (PDA). The influence of storage pressure, superheat, and nozzle diameter was also studied. Results show that the distribution of actual droplets with different velocities and diameters follows the normal distribution. Droplets mean three-dimensional velocities on the central axis of flashing jet decrease exponentially with the increase of axial distance. The droplets mean diameter first decreases exponentially and finally keeps sable at about 10 μm. Among three-dimensional velocities, the axial velocity is the highest and the vertical velocity is the lowest. Droplets mean three-dimensional velocities increase with the increase of storage pressure, superheat, and nozzle diameter. The droplets mean diameter decreases with the increase of superheat and nozzle diameter but increases with the increase of storage pressure.