【作者】 吕明宇；

【导师】 喻健良；

【作者基本信息】 大连理工大学 ， 安全技术及工程， 2008， 硕士

【摘要】 泄爆技术是防止工业生产过程中气体、粉尘发生毁灭性爆炸灾害的一种有效减灾技术手段。它是在爆炸初始或扩展阶段,将围包体内高温高压的燃烧物,通过泄压口,向安全方向泄出,使围包体免遭破坏,确保环境安全的技术。为了防止泄爆时喷出的火焰对周围人员和环境产生危害,并防止可能产生的“二次爆炸”危害,一般在泄爆口外需安装泄爆导管,将爆炸引至安全地带。因此,研究泄爆导管尺寸和结构的变化对泄爆过程的影响,对泄爆容器和泄爆导管的设计有很大的指导作用。本文对原有的Hartman粉尘爆炸实验装置进行了改进,自行设计了不同尺寸和结构的泄爆导管。以铝粉为介质,研究在不同泄爆条件下(即泄爆导管尺寸、结构、粉尘浓度和粒度等),容器内外压力的变化。主要的工作和结论如下:(1)直管泄爆试验研究单纯以直管作为泄爆导管,研究各因素对泄爆过程的影响。试验结果表明:容器内的最大泄爆超压和最大升压速率都随着泄爆直管长度的增加而增大,且最大泄爆超压随长度近似成对数增长;泄爆导管越粗,泄放效果越好;存在一个最佳爆炸浓度,在此浓度下容器内的最大泄爆超压和最大升压速率同时达到最大值,但此浓度随管径的增大而下降;粉尘粒度对泄爆超压无明显影响,而最大升压速率会明显随其增大而下降。(2)弯管泄爆试验研究带弯管的泄爆导管泄爆试验研究表明:弯管的引入会增大容器内的最大泄爆超压;弯管离泄爆口越近,对泄爆过程的影响越大;泄爆导管的结构越复杂,容器内的最大泄爆超压增加得越大;弯管的泄放效果相当于其弯曲长度2～3倍长直管的泄爆效果。(3)研究并分析了导管泄爆过程中出现的Helmohtz摆动、二次压力峰值和负向压力峰值偏大等异常试验现象。并且指出了各种现象的成因。本文的创新点是:(1)研究了泄爆导管的尺寸和结构在泄爆过程中对容器内外压力所产生的作用效果。给出了各种影响因素的定量关系,有助于泄爆导管的工程设计。(2)综合比较了各种结构泄爆导管的泄爆效果,给出了他们之间的排序关系,得到了用于指导泄爆导管设计的工程依据。更多还原

【Abstract】 Explosion venting is an effective technique method in industries to reduce or avoid the losses caused by explosions. In the early stages of an explosion, weak areas in the walls of plant open at low overpressures, and consequently, much of the explosion is dissipated in the open air. In this way, plant can be protected. But flame and blast ejecting from plant is damage to neighboring structure or equipment or personnel in the vicinity. To avoid potential damage above metioned, vent duct can be used outside of the vent to guide explosion to a safe place. Therefore, it is quite meaningful to study the influence of size and structure of vent duct on venting process, which has guiding significance on design of the vent vessel and the vent duct.In this paper, experimental studies on the explosion venting of aluminium dust is conducted in 1.3L Hartmann tube connected to a vent duct. The experiments under different venting conditions (size and structure of vent duct, dust concentration, partical size, at el) are performed and the perssure-time curves of the internal and external flow field are obtained. The main work and conclusions are as follows:(1) Study on explosion venting with straight duct Experiment is performed with only straight duct, and influence of various factors on venting process is studied. Several conclusions are obtained. The maximum reduced pressure and the maximum rate of pressure rise increases with length of straight duct increasing. Furthermore, the maximum reduced pressure increases with length at logarithmic growth. Vent duct being wider, the maximum reduced pressure is lower. There exists an optimum concentration making the maximum reduced pressure and the maximum rate of pressure rise reach to a maximum. This concentration decreases with diameter of straight duct increasing. The effect of dust particle size on the maximum reduced pressure can be ignored, while the maximum rate of pressure rise increases with particle size decreasing.(2) Study on explosion venting with bend Experimental results suggest that the maximum reduced pressure increases because of bend existing. The closer to vent bend is , the more remarkable influence of bend on venting process is. The more complicated structure of vent duct is, the higher the maximum reduced pressure is. Venting effect of bend is equal to that of straight duct that is two or three times as long as bend. (3) It is studied that abnormal experimental phenomenon ,such as Helmohltz oscillation, double pressure peak and negative pressure peak exceeding overpressure, appears during dust explosion venting. Furthermore, cause is analyzed for all kinds of phenomenon.The new ideas presented in this paper are as follows:(1) Influence of size and structure of vent duct on venting process is studied. Moreover, this paper give quantitative relation for various factors, which is helpful to design of vent duct.(2) Comprehensive compare venting effect for all kinds of vent duct. Sorting of venting effect for all kinds of vent duct is obtained, which can be used as basis for design of vent duct.更多还原