超细水雾增强与抑制瓦斯爆炸的实验研究

发布时间：2018-04-03 17:26

本文选题：瓦斯爆炸　切入点：超细水雾　出处：《大连理工大学》2013年硕士论文

【摘要】：气体/粉尘爆炸事故在煤矿开采、油气输运、粮食储存、核电等领域经常发生,尤以煤矿开采方面发生的瓦斯/煤尘爆炸事故最为频繁,每年给人民群众的生命财产安全造成了极大损失。因此,对气体/粉尘爆炸规律及高效防爆、抑爆技术的研究一直是该领域学者研究的热点。由于超细水雾具有成本低、耗水量少、环境友好、来源广泛等优点,且已被成功用来抑制不同类型火灾,因此将超细水雾技术应用于爆炸灾害的防治近年来得到了许多学者的重视。当前的研究多集中在超细水雾抑制开口条件下的瓦斯爆炸,这些结果表明超细水雾具有良好的抑爆效果。然而考虑到实际条件下,爆炸多发生在近于密闭的环境中,关于超细水雾对完全密闭空间内瓦斯爆炸的影响效果的研究还鲜见报道,且对加入超细水雾后可能引起的爆炸增强作用还缺少系统研究。因此,基于完全密闭和可视化的实验要求,本文设计并搭建了超细水雾条件下的气体／粉尘爆炸实验装置。运用相位多普勒粒子分析仪(PDPA)测量了不同雾化喷嘴的喷雾特性,分别采用高速摄像机和高频压力传感器记录了不同超细水雾条件下的瓦斯爆炸火焰和压力传播过程。分别采用单流体精细雾化喷头和超声波雾化系统研究了密闭管道内超细水雾对不同浓度瓦斯爆炸的影响效果。实验结果表明密闭管道内超细水雾可以对瓦斯爆炸起到增强和抑制两种作用。首先采用压力喷头研究了8%、9.5%、11%和12.5%四种浓度CH4/Air混合物在不同水雾量条件下的爆炸强度。实验发现喷入超细水雾后,各浓度瓦斯爆炸过程中的最大爆炸超压、最大压力上升速率和最大火焰传播速率均有所上升,火焰亮度也明显增大。最终保持在一个高于无水雾条件下的水平。分析认为由于雾化喷头所产生的雾滴粒径运动速度较高,且粒径较大,喷雾后对预混气体产生相当程度的湍流扰动作用,导致爆炸增强。另外,用喷头喷雾会出现显著的“二次反应”现象。这一现象的发生反映在火焰锋面到达管道顶端之后,全管道内的瓦斯火焰亮度会再一次增加。除了湍流扰动作用,分析认为,密闭管道内的高温高压条件可能导致了水与甲烷的重整反应、水分解反应等过程的发生,生成的H2、CO等的燃烧导致了二次反应中爆炸火焰亮度的再增加。其次,采用超声波雾化方式,研究了6%、9%、11%和13%四种浓度CH4/Air混合物在不同水雾量条件下的爆炸强度。超声波细水雾直接在爆炸管道内部生成。实验发现超声波雾化条件下,随着水雾量的增多,低浓度(6%)的瓦斯爆炸可以被完全抑制,高浓度条件下(9%,11%和13%)的瓦斯爆炸参数呈现先小幅增加后显著下降的趋势。随水雾量增加至一定程度,爆炸强度不再进一步降低。三种高浓度条件下,最大爆炸超压的最大降幅分别为21.1%、26.7%和22.9%；最大压力上升速率的最大降幅分别为71.7%、77.1%和52.0%。由于超细水雾蒸发后水蒸气分布不均匀可能引起流场中温度分布的不均匀,实验中还发现在已燃区中会出现蜂窝状“分区结构”,导致在火焰锋面到达管道顶端之前,已燃区中远离锋面处的火焰快速熄灭。分析认为密闭管道内超细水雾对瓦斯爆炸起到增强还是抑制的效果主要取决于两个方面：①喷雾时是否对预混气体造成显著的湍流扰动作用;②雾滴粒径能否足够小进而使得在爆炸压力波及火焰经过时,雾滴快速蒸发吸热衰减爆炸能量。本文实验结果表明,采用超声波雾化方法时,由于喷雾时不会对预混气体造成显著扰动,同时产生的雾滴粒径更为细小,能够实现对密闭管道内瓦斯爆炸的抑制效果。
[Abstract]:The gas / dust explosion accidents in coal mining, oil and gas transport, food storage, often occurred in areas such as nuclear power, especially for gas / coal mining and coal dust explosion accident occurred most frequently, every year caused a great loss of people's lives and property safety. Therefore, the gas / dust explosion and explosion proof law, study on anti explosion, technology has been the research focus of scholars in this field.
Because the water mist has the advantages of low cost, less water consumption, environment friendly, wide source etc, and has been successfully used to inhibit different types of fire prevention, so the application of ultra-fine water mist technology in explosion disaster has been the attention of many scholars in recent years. The current study focused suppression of gas explosion under the open conditions in the water mist, these results indicate that the ultra-fine water mist with explosion suppression effect is good. However, considering the actual conditions, the explosion occurred in the nearly closed environment, research on the effect of completely closed space of gas explosion of the ultra-fine water mist has rarely been reported, and the enhancement of adding ultra-fine water mist may cause the explosion is also a lack of system study.
Therefore, completely sealed and visual based experiments, this paper designs and builds the gas / dust explosion test apparatus of fine water mist conditions. By using phase Doppler particle analyzer (PDPA) spray characteristics of different nozzle were measured respectively by using a high speed camera machine and high frequency pressure sensor records the gas explosion pressure and flame propagation process water mist conditions. The effect of different pipeline water mist concentration gas explosion by using single fluid fine atomization nozzle and ultrasonic atomization system. The experimental results show that the pipeline to the enhancement and suppression of ultra-fine water mist can two effects on gas explosion.
Firstly, 8%, the pressure of the spray head 9.5%, 11% and 12.5% of the explosion intensity of four concentrations of CH4/Air mixture in the different conditions. The experimental results showed that under the weight of water mist sprayed into the water mist, the maximum explosion concentration in gas explosion overpressure, the maximum pressure rise rate and the maximum flame propagation rate was increased, the brightness of the flame also increased significantly. The final keep in a higher level. No water condition analysis that the atomizing nozzle produced by the droplet movement speed is higher, and the larger size of the spray of premixed gas turbulence generated considerable disturbance, causing the explosion increased. In addition, there will be significant for sprayer "the two reaction" phenomenon. After the occurrence of this phenomenon reflects to a pipe at the top of the flame front, the gas flame brightness all within the pipeline will again increase. In addition to the disturbance analysis of turbulence, recognition For example, the high temperature and high pressure conditions in the closed conduit may lead to the reforming reaction of water and methane. The combustion of H2, CO and so on caused the increase of the flame brightness in the two reaction.
Secondly, using ultrasonic atomization, on 6%, 9%, 11% and 13%, the explosion intensity of four concentrations of CH4/Air mixture in different conditions of water mist under the ultrasonic water mist generated in the explosion vessel directly. We found that ultrasonic atomization experiments, with the increase of water content, low concentration (6%) of the gas explosion can be completely inhibited under high concentrations (9%, 11% and 13%) of the gas explosion parameters showed a downward trend after the first significant increase slightly. With the water quantity increased to a certain extent, no explosion intensity is further reduced. Three kinds of high concentration conditions, the largest decline in the maximum explosion overpressure were 21.1%, 26.7% and 22.9%; the biggest drop in the maximum pressure rising rate were 71.7%, 77.1% and 52.0%. after the evaporation of water vapor due to water mist may cause uneven distribution of flow field temperature distribution is not uniform, it is found that in the burned area The honeycomb "zoning" will result in the rapid extinction of the flame from the far front of the burning zone before the front of the flame reaches the top of the pipe.
Analysis shows that the pipeline of gas explosion of ultra-fine water mist to enhance or mainly depends on the inhibitory effect on two aspects: whether the cause significant turbulence effects on the premixed gas spray; the droplet diameter can be small enough so that the explosion pressure affected by flame, the rapid evaporation of droplets. The explosion energy decay heat the experimental results show that the ultrasonic atomization method, because will not cause a significant disturbance of the premixed gas spray, while the droplet diameter is more small, can achieve the suppression effect of gas pipeline explosion.

【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TD712.7

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