本文關(guān)鍵詞： 液化天然氣 泄漏 擴(kuò)散 濃度分布 危險(xiǎn)區(qū)域　出處：《大連理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：液化天然氣(Liquefied Natural Gas,LNG)作為一種清潔、高效的能源,在工業(yè)生產(chǎn)與日常生活中受到廣泛應(yīng)用,由于LNG具有低溫、可燃等特性,因而其安全問題一直備受關(guān)注�，F(xiàn)有研究結(jié)果表明,液化天然氣發(fā)生泄漏事故之后,泄漏出來的低溫液體及其蒸發(fā)形成的低溫蒸氣云將會對周圍的設(shè)備、人員造成危害；若遇到火源,將形成池火災(zāi)或蒸氣云火災(zāi),造成的危害更是不可估量,而外界環(huán)境因素則進(jìn)一步影響了其危害程度。因此,有必要對液化天然氣的泄漏擴(kuò)散過程及其影響因素進(jìn)行研究,預(yù)測事故造成的危害范圍,以指導(dǎo)制定應(yīng)急預(yù)案。鑒于此,本文進(jìn)行的研究工作主要有：(1)以高斯擴(kuò)散模型為基礎(chǔ),提出了非點(diǎn)源高斯煙羽混合模型,克服了高斯煙羽模型不能計(jì)算連續(xù)泄漏源的初期濃度分布及非點(diǎn)源的泄漏擴(kuò)散問題。以MATLAB軟件為計(jì)算工具,建立了LNG泄漏事故危害評估程序,可快速繪制出天然氣的動態(tài)擴(kuò)散過程,并自動進(jìn)行危險(xiǎn)區(qū)域劃分,該過程可在數(shù)秒內(nèi)完成,可及時(shí)為救援過程提供指導(dǎo)。(2)從流體動力學(xué)角度出發(fā),利用CFD軟件FLUENT,采用Realizable k-ε模型、組分輸運(yùn)模型、DPM模型,對液化天然氣泄漏事故中涉及的流體流動、物質(zhì)擴(kuò)散以及蒸發(fā)相變問題進(jìn)行了數(shù)值計(jì)算。選用了國外大型LNG泄漏實(shí)驗(yàn)-Burro系列實(shí)驗(yàn)的數(shù)據(jù)進(jìn)行模型驗(yàn)證,結(jié)果表明：建立的預(yù)測模型可以很好地模擬氣云的運(yùn)動擴(kuò)散過程；監(jiān)測點(diǎn)及固定平面內(nèi)濃度分布規(guī)律的計(jì)算結(jié)果與實(shí)驗(yàn)值比較吻合。(3)通過數(shù)值實(shí)驗(yàn),研究了大氣條件、地理環(huán)境等對氣云擴(kuò)散過程的影響,主要研究結(jié)果表明：大氣風(fēng)速對氣云運(yùn)動擴(kuò)散的影響主要體現(xiàn)在順風(fēng)方向上,風(fēng)速越大,對氣云的平流輸運(yùn)及混合稀釋作用越明顯,導(dǎo)致氣云的運(yùn)動擴(kuò)散越快；障礙物的存在增加了其附近流場的湍流程度,促進(jìn)了氣云與周圍空氣的混合,但阻礙了氣云向下風(fēng)方向的運(yùn)動,減小了有害區(qū)域在下風(fēng)方向的范圍；上坡地面具有與障礙物類似的特性,增強(qiáng)了周圍大氣對氣云的稀釋作用,因而形成的危害區(qū)域消散較快,而下坡地面由于地勢低洼,氣云受重力作用堆積于下坡處,不利于擴(kuò)散,因而形成的危害區(qū)域不容易消散。(4)以LNG泄漏擴(kuò)散模型為基礎(chǔ),耦合泄漏源模型,對大型儲罐的氣相泄漏、液相泄漏及圍堰作用進(jìn)行了模擬分析,結(jié)果表明：液相泄漏事故造成的危害顯著大于氣相泄漏事故；圍堰阻礙了液池的擴(kuò)展和氣云的擴(kuò)散,降低了圍堰外圍區(qū)域的危險(xiǎn)性,但增大了圍堰內(nèi)部區(qū)域的危險(xiǎn)程度。最終,參照某LNG接收站的實(shí)際場景,建立了該接收站的LNG儲罐泄漏擴(kuò)散模型,對形成的危害區(qū)域進(jìn)行了預(yù)測,為應(yīng)急救援提供了建議。
[Abstract]:As a kind of clean and efficient energy, liquefied natural gas (LNG) has been widely used in industrial production and daily life. Because of its characteristics of low temperature and flammability, the safety problems of LNG have been paid much attention to. After the leakage of liquefied natural gas (LNG), the leaking low-temperature liquid and the low-temperature vapor cloud formed by evaporation will cause harm to the equipment and personnel around it; if the fire is encountered, it will form a pool fire or a steam cloud fire. The harm caused by the accident is even more incalculable, and the external environmental factors have further affected the harm degree. Therefore, it is necessary to study the leakage and diffusion process of liquefied natural gas and its influencing factors, and to predict the harm scope caused by the accident. In view of this, the main research work carried out in this paper is: 1) based on Gao Si's diffusion model, a mixed model of non-point Gao Si smoke plume is proposed. This paper overcomes the problem that Gao Si's smoke plume model can not calculate the initial concentration distribution of continuous leakage source and the leakage diffusion of non-point source. The MATLAB software is used as the calculation tool to establish the LNG leakage accident hazard assessment program. The dynamic diffusion process of natural gas can be drawn quickly and the dangerous area can be divided automatically. The process can be completed in a few seconds, and can provide guidance for the rescue process in time.) from the point of view of fluid dynamics, Realizable k- 蔚 model is adopted by using CFD software fluent. The component transport model and the DPM model are used to numerically calculate the fluid flow, material diffusion and evaporation phase transition in liquefied natural gas (LNG) leakage accident. The results show that the predicted model can well simulate the movement and diffusion process of the gas cloud, and the calculated results of the concentration distribution in the monitoring point and the fixed plane are in good agreement with the experimental values. (3) the atmospheric conditions are studied through numerical experiments. The main results show that the influence of atmospheric wind speed on the diffusion of gas cloud motion is mainly reflected in the direction of downwind, the greater the wind speed, the more obvious the advection transport and mixed dilution of gas cloud. The presence of obstacles increases the turbulence level of the flow field near the gas cloud and promotes the mixing of the gas cloud with the surrounding air, but hinders the movement of the downward wind direction of the gas cloud and reduces the range of the harmful area in the downwind direction. The upper slope surface has the characteristics similar to the obstacle, which enhances the dilution effect of the surrounding atmosphere on the gas cloud, and thus causes the dangerous area to dissipate more quickly, while the downward slope surface is accumulated in the downhill by gravity because of the low-lying terrain. Based on the LNG leakage diffusion model and coupling the leakage source model, the gas phase leakage, liquid phase leakage and cofferdam effect of large storage tanks are simulated and analyzed. The results show that the damage caused by the liquid phase leakage accident is significantly greater than that caused by the gas phase leakage accident, and the cofferdam hinders the expansion of the liquid pool and the diffusion of the gas cloud, reduces the danger of the surrounding region of the cofferdam, but increases the danger degree of the inner region of the cofferdam. According to the actual situation of a certain LNG receiving station, the leakage and diffusion model of the LNG storage tank of the receiving station is established, and the hazard area is predicted, which provides suggestions for emergency rescue.
【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】：2015
【分類號】：TE88;TQ021.4

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本文編號：1534894