發(fā)布時(shí)間：2018-06-14 15:47

  本文選題：液化天然氣 + 轉(zhuǎn)儲(chǔ)系統(tǒng)��； 參考：《武漢理工大學(xué)》2014年博士論文

【摘要】：能源是世界發(fā)展的重要資源，環(huán)境是人類生存的基本條件，能源與環(huán)境問題是當(dāng)今人類面臨的世界性難題，解決該難題，既要開發(fā)新型能源，又要保護(hù)環(huán)境免受污染。LNG是清潔高效的能源，擁有豐富的來(lái)源，合理開發(fā)和利用LNG是人類解決未來(lái)環(huán)境與能源問題的重要途徑，受到國(guó)內(nèi)外的高度重視。我國(guó)是LNG利用大國(guó)，大量的LNG通過船舶從國(guó)外進(jìn)口，由港口通過管線轉(zhuǎn)輸至儲(chǔ)罐進(jìn)行儲(chǔ)存。LNG在轉(zhuǎn)儲(chǔ)過程中會(huì)面臨著火災(zāi)、爆炸、熱力學(xué)毀壞、快速相變、低溫破壞、窒息等危害，危害的發(fā)生會(huì)嚴(yán)重影響生命和財(cái)產(chǎn)的安全。 文中研究對(duì)象為到港LNG船舶、LNG傳輸管線和LNG儲(chǔ)罐所構(gòu)成的LNG轉(zhuǎn)儲(chǔ)系統(tǒng)。鑒于LNG轉(zhuǎn)儲(chǔ)系統(tǒng)的危險(xiǎn)性，文中在國(guó)內(nèi)外研究成果的基礎(chǔ)上，對(duì)LNG船舶、儲(chǔ)罐、管線的泄漏逸散機(jī)理、LNG液池的形成、演變、蒸氣云的擴(kuò)散進(jìn)行了研究，具體研究?jī)?nèi)容與結(jié)論如下： （1）將液化天然氣的港口轉(zhuǎn)運(yùn)及儲(chǔ)存作為一個(gè)完整的系統(tǒng)，對(duì)船舶在碼頭裝卸區(qū)LNG的泄漏原因、初始泄漏率模型、泄漏口的位置及其他影響因素等問題進(jìn)行了研究。發(fā)展了LNG轉(zhuǎn)儲(chǔ)系統(tǒng)泄漏逸散的初始泄漏率模型，根據(jù)泄漏口與水線面的位置關(guān)系，將LNG船舶的泄漏逸散分為水線面以上、水線面和水線面以下三種情況，以一艘雙層船殼的薄膜型LNG船舶為實(shí)例，對(duì)三種情況下的泄漏逸散分別進(jìn)行了計(jì)算和預(yù)測(cè)。所發(fā)展的初始泄漏率模型具有一定的適應(yīng)性；對(duì)于雙層船殼的薄膜型LNG船舶，當(dāng)泄漏口位于水面以下時(shí)，無(wú)論船舶僅外殼單層穿刺還是外殼和儲(chǔ)罐雙層穿刺，，最終都會(huì)達(dá)到一種平衡狀態(tài)。 （2）對(duì)LNG罐區(qū)和管線的泄漏風(fēng)險(xiǎn)、LNG管線泄漏蒸發(fā)率、罐內(nèi)翻滾現(xiàn)象進(jìn)行了研究。研究了LNG儲(chǔ)罐的翻滾現(xiàn)象，給出了消除分層和翻滾的措施，通過分開儲(chǔ)存或內(nèi)部攪拌充注方式，使LNG儲(chǔ)罐內(nèi)的密度差和溫度差減小為零，可以防止LNG分層與翻滾。建立了LNG管線泄漏蒸發(fā)率模型，以LNG通過管線轉(zhuǎn)到儲(chǔ)罐的過程中管線發(fā)生完全破裂為例，對(duì)泄漏蒸發(fā)率進(jìn)行了理論預(yù)測(cè)。研究了在LNG泄漏逸散的過程中能量的傳遞和不同地面基質(zhì)的傳熱，在考慮了不同地面基質(zhì)的熱力學(xué)特性后所建立的LNG蒸發(fā)率模型能夠較好的反應(yīng)LNG的蒸發(fā)。 （3）對(duì)泄漏中液池的演變過程、演變模型、液池蒸發(fā)、熱通量變化規(guī)律、池火等進(jìn)行了研究。LNG轉(zhuǎn)儲(chǔ)系統(tǒng)出現(xiàn)裂口形成射流，液體射流會(huì)分裂成霧狀小液滴，小液滴在下落過程中將會(huì)部分蒸發(fā)或者全部蒸發(fā)。當(dāng)LNG射流量較大時(shí)，將會(huì)形成液池，當(dāng)LNG液池的厚度超出維持穩(wěn)定的最小值時(shí)，穩(wěn)定性將會(huì)被打破，LNG液池不斷地?cái)U(kuò)展和蒸發(fā)，直至液池的半徑達(dá)到最大值。隨著蒸發(fā)率的增加，沸騰氣泡的密度也隨著增加，當(dāng)液體和蒸氣的相互作用阻止了流體向過熱表面的接觸導(dǎo)致溫度足夠高時(shí)，核沸騰將會(huì)停止，隨著過熱溫度的繼續(xù)增加，沸騰變得相對(duì)穩(wěn)定，逐漸成為過渡沸騰。當(dāng)熱通量達(dá)到最小值時(shí)，過渡沸騰轉(zhuǎn)變?yōu)楸∧し序v。泄漏之初液體的沸騰溫度幾乎沒有變化，液池蒸發(fā)的后期，蒸氣的組分幾乎不變，但是液體的沸騰溫度劇烈升高。對(duì)于大型LNG液池的燃燒，建立了池火的簡(jiǎn)化模型，能較好的反應(yīng)火焰的特點(diǎn)和在不同風(fēng)向時(shí)火焰的發(fā)展趨勢(shì)。 （4）對(duì)LNG泄漏后蒸氣云的擴(kuò)散過程、影響因素、擴(kuò)散距離模型進(jìn)行研究。由于風(fēng)的存在，將使煙羽向下風(fēng)向擴(kuò)展。在煙羽和攜帶的空氣之間存在一種平衡，煙羽向下風(fēng)向擴(kuò)展，密度快速降低，而其攜帶的空氣將阻止這一現(xiàn)象的快速發(fā)生，使擴(kuò)展以及密度的快速降低得到平衡。在考慮了風(fēng)速、大氣穩(wěn)定度、地面粗糙度、障礙物以及重氣屬性等因素后所建立的LNG蒸氣云擴(kuò)散在下風(fēng)向的最大距離的數(shù)學(xué)模型具有良好的適用性。 （5）對(duì)LNG轉(zhuǎn)儲(chǔ)系統(tǒng)的事故預(yù)防及應(yīng)急響應(yīng)措施進(jìn)行了研究。研究LNG轉(zhuǎn)儲(chǔ)系統(tǒng)的泄漏逸散機(jī)理的最終目的是要防止LNG轉(zhuǎn)儲(chǔ)系統(tǒng)事故的發(fā)生，降低由LNG轉(zhuǎn)儲(chǔ)過程中的泄漏逸散事故所造成的損失。根據(jù)LNG轉(zhuǎn)儲(chǔ)系統(tǒng)的泄漏逸散機(jī)理，主要從轉(zhuǎn)儲(chǔ)系統(tǒng)的安全管理、事故的預(yù)防、應(yīng)急響應(yīng)措施的制定等三個(gè)方面進(jìn)行了研究。
[Abstract]:Energy is an important resource for the development of the world. The environment is the basic condition for human survival. Energy and environmental problems are the world's difficult problems facing today. To solve this problem, we should develop new energy and protect the environment from pollution.LNG is a clean and efficient energy, have a rich source. The rational development and use of LNG is a human solution. The important way to come to the problem of environment and energy is highly valued at home and abroad. China is a big country in which LNG uses a large country. A large number of LNG are imported by ships from abroad. The storage of.LNG from the port through the pipeline to storage tank will face fire, explosion, thermodynamic destruction, rapid phase change, low temperature damage, asphyxiation and other hazards. It will seriously affect the safety of life and property.
In this paper, the research object is the LNG dump system of port LNG, LNG transmission pipeline and LNG storage tank. In view of the danger of LNG dump system, based on the research results at home and abroad, the leakage and escape mechanism of LNG ships, storage tanks and pipelines, the formation of LNG liquid pool, the evolution of LNG liquid pool and the diffusion of steam clouds are studied. The conclusions are as follows:
(1) take the port transport and storage of liquefied natural gas as a complete system, study the causes of the leakage of LNG, the initial leakage rate model, the location of the leakage and other influencing factors, and develop the initial leakage rate model of the leakage and escape of the LNG dump system, according to the position of the leakage and the water line. The leakage and escaping of the LNG ship is divided into three cases above the waterline surface, the waterline surface and the waterline, and the leakage and escape of the three cases are calculated and predicted with the example of a thin film type LNG ship of a double hull hull. A membrane type LNG ship, when the leakage is below the surface of the water, will eventually reach a state of balance, regardless of the single layer puncture of the shell, or the double layer piercing of the shell and the tank.
(2) the leakage risk of the LNG tank and the pipeline, the evaporation rate of the LNG pipeline and the rolling phenomenon in the tank are studied. The roll phenomenon of the LNG tank is studied. The measures to eliminate the stratification and rolling are given. The density difference and the temperature difference in the LNG storage tank are reduced to zero by the separate storage or internal stirring filling method, which prevents the LNG layer from delamination and turn over. The evaporation rate model of the LNG pipeline leakage was established. The leakage evaporation rate was predicted by the case of complete rupture of the pipeline in the process of transferring LNG through the pipeline to the tank. The transfer of energy in the process of LNG leakage and the heat transfer of different ground substrates were studied, and the thermodynamic properties of different ground substrates were considered. The LNG evaporation rate model can better reflect the evaporation of LNG.
(3) the evolution process of the liquid pool in the leakage, the evolution model, the evaporation of the liquid pool, the law of the change of the heat flux, the pool fire, etc. have been studied to study the formation of the jets in the.LNG dump system. The liquid jet will split into a small fog droplet, and the small droplets will be partially evaporated or all evaporated during the falling process. When the LNG discharge is large, a liquid pool will be formed. When the thickness of the LNG tank exceeds the minimum value for maintaining stability, the stability will be broken and the LNG pool expands and evaporates until the radius of the liquid pool reaches the maximum. As the evaporation rate increases, the density of the boiling bubbles increases as the interaction between the liquid and steam prevents the fluid from contacting the overheated surface. When the heating temperature continues to increase, the boiling will become relatively stable and gradually become a transition boiling. When the heat flux reaches the minimum, the transition boiling is transformed into a film boiling. The boiling temperature of the initial liquid is almost unchanged, and the vapour component is almost invariable in the later period of the liquid pool evaporation, but the liquid is almost unchanged. The boiling temperature rises violently. For the combustion of the large LNG liquid pool, a simplified model of the pool fire is established, which can better reflect the characteristics of the flame and the development trend of the flame at different wind direction.
(4) the diffusion process of the vapor cloud after LNG leakage, the influencing factors and the diffusion distance model are studied. Due to the existence of the wind, the smoke plume will expand downward. There is a balance between the smoke plume and the air carried, the smoke plume expands downward and the density decreases rapidly, and the air carrying the plume will prevent the rapid occurrence of this phenomenon and make the expansion of the phenomenon. The rapid reduction of the density is balanced. The mathematical model of the maximum distance of LNG vapor cloud diffusion in the downward wind direction is well applicable in the consideration of the factors such as wind speed, atmospheric stability, ground roughness, obstacles and heavy gas properties.
(5) the accident prevention and emergency response measures of the LNG dump system are studied. The final purpose of the study of the leakage and escape mechanism of the LNG dump system is to prevent the occurrence of the accident in the LNG dump system and reduce the loss caused by the leakage and escape accident in the LNG dump process. The leakage and escape mechanism of the LNG dump system is mainly from the transfer of the dump system. System safety management, accident prevention, emergency response measures and other three aspects were studied.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TE88;U698.5

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