本文選題：瓦斯爆炸　切入點(diǎn)：超細(xì)水霧　出處：《大連理工大學(xué)》2013年碩士論文

【摘要】：氣體/粉塵爆炸事故在煤礦開采、油氣輸運(yùn)、糧食儲存、核電等領(lǐng)域經(jīng)常發(fā)生,尤以煤礦開采方面發(fā)生的瓦斯/煤塵爆炸事故最為頻繁,每年給人民群眾的生命財(cái)產(chǎn)安全造成了極大損失。因此,對氣體/粉塵爆炸規(guī)律及高效防爆、抑爆技術(shù)的研究一直是該領(lǐng)域?qū)W者研究的熱點(diǎn)。 由于超細(xì)水霧具有成本低、耗水量少、環(huán)境友好、來源廣泛等優(yōu)點(diǎn),且已被成功用來抑制不同類型火災(zāi),因此將超細(xì)水霧技術(shù)應(yīng)用于爆炸災(zāi)害的防治近年來得到了許多學(xué)者的重視。當(dāng)前的研究多集中在超細(xì)水霧抑制開口條件下的瓦斯爆炸,這些結(jié)果表明超細(xì)水霧具有良好的抑爆效果。然而考慮到實(shí)際條件下,爆炸多發(fā)生在近于密閉的環(huán)境中,關(guān)于超細(xì)水霧對完全密閉空間內(nèi)瓦斯爆炸的影響效果的研究還鮮見報(bào)道,且對加入超細(xì)水霧后可能引起的爆炸增強(qiáng)作用還缺少系統(tǒng)研究。 因此,基于完全密閉和可視化的實(shí)驗(yàn)要求,本文設(shè)計(jì)并搭建了超細(xì)水霧條件下的氣體／粉塵爆炸實(shí)驗(yàn)裝置。運(yùn)用相位多普勒粒子分析儀(PDPA)測量了不同霧化噴嘴的噴霧特性,分別采用高速攝像機(jī)和高頻壓力傳感器記錄了不同超細(xì)水霧條件下的瓦斯爆炸火焰和壓力傳播過程。分別采用單流體精細(xì)霧化噴頭和超聲波霧化系統(tǒng)研究了密閉管道內(nèi)超細(xì)水霧對不同濃度瓦斯爆炸的影響效果。實(shí)驗(yàn)結(jié)果表明密閉管道內(nèi)超細(xì)水霧可以對瓦斯爆炸起到增強(qiáng)和抑制兩種作用。 首先采用壓力噴頭研究了8%、9.5%、11%和12.5%四種濃度CH4/Air混合物在不同水霧量條件下的爆炸強(qiáng)度。實(shí)驗(yàn)發(fā)現(xiàn)噴入超細(xì)水霧后,各濃度瓦斯爆炸過程中的最大爆炸超壓、最大壓力上升速率和最大火焰?zhèn)鞑ニ俾示兴仙?火焰亮度也明顯增大。最終保持在一個(gè)高于無水霧條件下的水平。分析認(rèn)為由于霧化噴頭所產(chǎn)生的霧滴粒徑運(yùn)動(dòng)速度較高,且粒徑較大,噴霧后對預(yù)混氣體產(chǎn)生相當(dāng)程度的湍流擾動(dòng)作用,導(dǎo)致爆炸增強(qiáng)。另外,用噴頭噴霧會出現(xiàn)顯著的“二次反應(yīng)”現(xiàn)象。這一現(xiàn)象的發(fā)生反映在火焰鋒面到達(dá)管道頂端之后,全管道內(nèi)的瓦斯火焰亮度會再一次增加。除了湍流擾動(dòng)作用,分析認(rèn)為,密閉管道內(nèi)的高溫高壓條件可能導(dǎo)致了水與甲烷的重整反應(yīng)、水分解反應(yīng)等過程的發(fā)生,生成的H2、CO等的燃燒導(dǎo)致了二次反應(yīng)中爆炸火焰亮度的再增加。 其次,采用超聲波霧化方式,研究了6%、9%、11%和13%四種濃度CH4/Air混合物在不同水霧量條件下的爆炸強(qiáng)度。超聲波細(xì)水霧直接在爆炸管道內(nèi)部生成。實(shí)驗(yàn)發(fā)現(xiàn)超聲波霧化條件下,隨著水霧量的增多,低濃度(6%)的瓦斯爆炸可以被完全抑制,高濃度條件下(9%,11%和13%)的瓦斯爆炸參數(shù)呈現(xiàn)先小幅增加后顯著下降的趨勢。隨水霧量增加至一定程度,爆炸強(qiáng)度不再進(jìn)一步降低。三種高濃度條件下,最大爆炸超壓的最大降幅分別為21.1%、26.7%和22.9%；最大壓力上升速率的最大降幅分別為71.7%、77.1%和52.0%。由于超細(xì)水霧蒸發(fā)后水蒸氣分布不均勻可能引起流場中溫度分布的不均勻,實(shí)驗(yàn)中還發(fā)現(xiàn)在已燃區(qū)中會出現(xiàn)蜂窩狀“分區(qū)結(jié)構(gòu)”,導(dǎo)致在火焰鋒面到達(dá)管道頂端之前,已燃區(qū)中遠(yuǎn)離鋒面處的火焰快速熄滅。 分析認(rèn)為密閉管道內(nèi)超細(xì)水霧對瓦斯爆炸起到增強(qiáng)還是抑制的效果主要取決于兩個(gè)方面：①噴霧時(shí)是否對預(yù)混氣體造成顯著的湍流擾動(dòng)作用;②霧滴粒徑能否足夠小進(jìn)而使得在爆炸壓力波及火焰經(jīng)過時(shí),霧滴快速蒸發(fā)吸熱衰減爆炸能量。本文實(shí)驗(yàn)結(jié)果表明,采用超聲波霧化方法時(shí),由于噴霧時(shí)不會對預(yù)混氣體造成顯著擾動(dòng),同時(shí)產(chǎn)生的霧滴粒徑更為細(xì)小,能夠?qū)崿F(xiàn)對密閉管道內(nèi)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.

【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TD712.7

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