管道内预混可燃气体爆炸与抑爆的研究

【作者】 周崇；

【导师】 喻健良；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2004， 硕士

【摘要】 可燃气体爆炸事故往往导致惨重的人员伤亡和巨大的财产损失。考虑多数情况下可燃气体都是在管路中流动的，因此关于管路中爆炸波的传播状况及如何抑制管中爆炸波传播的研究已成为爆炸研究的重点之一。 本文主要研究压力波和火焰在圆形管道和多层丝网结构内传播时其参数的变化规律以及参数之间的耦合关系。本文的主要工作和结论如下： (1)自行设计、加工、购买、组建了圆形管道内预混可燃气体爆炸及抑爆实验装置。并以乙炔／空气混合气为实验介质进行了关于爆炸波在受约束空间中传播与抑制的实验研究。实验条件如下：乙炔浓度为化学计量比(7.75％)，爆炸初压为常压，管道内径为81mm，长度为1.4～2.9m，点火端密闭，出口端开放。多层丝网结构与管道轴线垂直，丝网材质为不锈钢。 (2)根据实验结果将超压的变化过程分为四个阶段，将气体燃烧的变化过程分为三个阶段。得到了前驱冲击波峰值的经验公式、以及前驱冲击波末端与火焰面的相对时间及相对位置关系的经验公式、最大超压值在时间上的变化规律的经验公式、燃烧时间与火焰传播速度及测点位置关系的经验公式。前驱冲击波阶段超压上升曲线比较规则，且压力上升速率逐渐增加，离点火处越远压力上升速率增加得越快。实验中燃烧反应区的宽度要远大于湍流燃烧理论中的反应区宽度。测到的管内各处最大超压值和二次反冲压力差值为管道内爆炸的预防提供了参考。 (3)对爆燃转爆轰过程(DDT)进行了初步研究，观察到此过程中前驱冲击波阵面仍然行进在火焰面的前方，但二者的间距在减小。火焰面紧跟在激波前缘的后面，二者同速传播，超压峰值的位置与火焰面重合。 (4)利用理论模型对火焰传播速度进行了计算，并将火焰传播速度的实验值与计算值进行了对比分析。依据实验值得到了管内火焰传播速度的经验公式。 (5)分析了多层丝网结构对管内传播中的火焰的淬熄能力。得到了临界淬熄速度、临界淬熄压差、临界淬熄量(临界淬熄速度与临界淬熄压差之积)与丝网层数、丝网目数、金属丝径这三个多层丝网结构的几何参数之间关系的经验公式。介绍了多层丝网结构对压力波的抑制效果。得出了最大超压下降比率与多层丝网结构的三个几何参数之间的数学关系式。更多还原

【Abstract】 Flammable gases explosions can cause great casualty and economic loss. Since flammable gases usually flow in pipelines, the investigations into propagation of explosion waves and its suppression technology become one of key points of explosion researches.Experimental investigations are carried out to analyze variation regulations of parameters in flow field and their couple relations as explosion waves and flame propagating along tube or through multi-layer mesh construction. The main work and conclusions of this paper are as follows:(1)Experimental apparatus used for explosion and explosion suppression of flammable gases in tube are designed and set up. With premixed ethyne-air gases, experimental investigations about explosion waves and flame propagating in tube are dealt with. Experimental conditions are set as follows: Stoichiometric rate and atmospheric pressure are used for initial concentration of Ethyne and initial pressure; the inside diameter and length of tube, which is closed at ignition end and open at the other, are 81mm and 1.4-2.9m respectively; multi-layer mesh construction made of stainless steel, is vertical to tube axle.(2) According to experimental results, the variations of overpressure and flame can be described as four and three phases respectively. Some empirical formulae about, such as peak value of precursory shock waves, relative time and relative position of the of precursory shock waves and flame front, the variations of overpressure with time, the relationships between combustion time and flame propagation velocity and measuring points, are obtained. At precursory shock wave segment, overpressure-increasing curves are regular. With acceleration of pressure increasing rate, the farther measuring point is apart from ignition point, the faster pressure-increasing rate is. The width of combustion region is far bigger than theoretical value in turbulent combustion theory. Difference value of peak overpressure and reactive pressure for the second time can provide references for explosion prevention in tubes.(3) Preliminary study on deflagration to detonation (DDT) process is made. It is found that precursory shock waves still travel before the flame front, and the distance between them decreases gradually. Flame front closely follows Shockwaves at the same speed, and location of peak overpressure is coincident with flame front.(4) Based on theoretical model, flame propagation speed is computed and compared with experimental value. Empirical formula about flame propagation speed in tube is obtained.(5) The effects of multi-layer mesh construction on flame propagation in tubeare analyzed. Empirical formulas about relationship between critical values, include of quenching speed, quenching pressure difference and quenching amount (the product of quenching speed and quenching pressure difference), and geometrical parameters, such as layer, screen mesh and wire diameter, are obtained. Suppression effects of multi-layer mesh construction on explosion waves are introduced, and mathematical relations between decreasing rate of the maximum overpressure and three geometrical parameters are obtained.更多还原