本文選題：LNG球閥 + 傳熱　； 參考：《蘭州交通大學(xué)》2017年碩士論文

【摘要】：近年來,隨著我國能源政策的調(diào)整,LNG(液化天然氣)產(chǎn)業(yè)在我國得到了快速的發(fā)展,其使用量也在急劇增加。而在天然氣的液化及液化天然氣的運輸、貯存等方面都需要大量的低溫閥門,因此隨著LNG產(chǎn)業(yè)的迅速發(fā)展,LNG低溫閥門的需求量也會越來越大,所以LNG低溫閥門也將在我國得到空前的發(fā)展。目前,傳統(tǒng)的LNG低溫閥門在設(shè)計上和安全性上都存在很多不足之處,如閥桿閥蓋過長、無法安全泄壓、過臨界設(shè)計等問題。針對傳統(tǒng)LNG低溫閥門存在的上述問題,首先,本文從傳熱的角度分析,采用散冷翅片技術(shù)解決閥蓋、閥桿過長問題。即在LNG超低溫閥門長頸閥蓋上加裝一組散冷翅片,增大閥蓋頸部與環(huán)境的換熱面積,強化閥蓋頸部與環(huán)境的對流換熱,延緩并阻止冷量繼續(xù)向上傳遞,以此達(dá)到降低閥蓋和閥桿的高度,減小閥門啟閉時閥桿的扭矩,延長閥門的受用壽命。其次,應(yīng)用LNG自增壓原理及低溫預(yù)緊應(yīng)力與輸送壓力匹配的原理,解決LNG球閥無法安全泄壓及過臨界設(shè)計問題。即在球體上安裝LNG壓力調(diào)節(jié)閥,用于導(dǎo)出LNG球閥啟閉后盲區(qū)內(nèi)的LNG,達(dá)到安全泄壓目的,從而提高LNG過程控制效率和閥門的安全性;此外因LNG壓力調(diào)節(jié)閥及時泄壓,可降低閥門及系統(tǒng)的設(shè)計壓力,提高閥門和系統(tǒng)運行的安全性與可靠性。最后,根據(jù)低溫閥門設(shè)計手冊及相關(guān)標(biāo)準(zhǔn),對LNG球閥及LNG壓力調(diào)節(jié)閥結(jié)構(gòu)進(jìn)行了合理設(shè)計,并基于傳熱學(xué)理論,結(jié)合數(shù)值模擬對所設(shè)計的帶有散冷翅片的長頸閥蓋及LNG壓力調(diào)節(jié)閥進(jìn)行了以下研究:(1)對帶有散冷翅片的長頸閥蓋結(jié)構(gòu)組件建立物理模型。首先根據(jù)傳熱學(xué)相關(guān)理論,對LNG超低溫球閥的保冷層厚度進(jìn)行理論計算和模擬計算,之后將兩種結(jié)果進(jìn)行對比分析得出保冷層最佳厚度;其次運用Solidworks軟件中的Simulation插件對長頸閥蓋結(jié)構(gòu)組件溫度場分布進(jìn)行模擬研究,得出散冷翅片位置最佳模型及片數(shù)最佳模型,最終確定出長頸閥蓋結(jié)構(gòu)最佳模型及加裝散冷翅片后閥頸的實際高度。(2)根據(jù)流體力學(xué)相關(guān)理論,運用Solidworks軟件中的Flow Simulation插件對LNG壓力調(diào)節(jié)閥的流場進(jìn)行模擬,得出其流場溫度、壓力、速度及密度分布規(guī)律。(3)根據(jù)傳熱學(xué)和熱力學(xué)相關(guān)理論,采用熱-結(jié)構(gòu)耦合模型對長頸閥蓋結(jié)構(gòu)組件進(jìn)行熱應(yīng)力分析,得出其應(yīng)力、位移、應(yīng)變變化規(guī)律;此外,對LNG壓力調(diào)節(jié)閥的預(yù)緊彈簧進(jìn)行了熱應(yīng)力分析,得出了其抗剪應(yīng)力及軸向位移的變化,并進(jìn)行了理論驗證。本文基于理論計算和模擬分析的方法,以LNG低溫球閥為研究對象,對如何降低長頸閥閥蓋的高度,如何安全泄壓等關(guān)鍵問題進(jìn)行了分析和研究,并得出了一些對有實際意義的結(jié)論,為LNG低溫閥門的發(fā)展提供參考。
[Abstract]:In recent years, with the adjustment of China's energy policy, LNG (liquefied natural gas) industry has been rapidly developed in China, its use is also increasing rapidly. In the aspects of liquefied natural gas and transportation and storage of LNG, a large number of cryogenic valves are needed. Therefore, with the rapid development of LNG industry, the demand for LNG cryogenic valves will also be increasing. So LNG low-temperature valve will also get unprecedented development in our country. At present, there are many shortcomings in the design and safety of the traditional LNG cryogenic valve, such as the valve stem cover is too long, the pressure can not be safely released, and so on. In view of the above problems existing in traditional LNG cryogenic valves, firstly, this paper analyzes the heat transfer from the point of view of the use of cold fin technology to solve the valve cap, the stem is too long. That is, add a group of cold fins to the long neck cover of LNG ultra-low temperature valve, increase the heat transfer area between the cover neck and the environment, strengthen the convection heat transfer between the cover neck and the environment, delay and prevent the further transfer of cold volume up, It can reduce the height of valve cover and stem, reduce the torque of valve stem when opening and closing, and prolong the service life of valve. Secondly, the principle of LNG self-pressurization and the matching principle of low-temperature pre-tightening stress and conveying pressure are applied to solve the problems of safe pressure relief and over-critical design of LNG ball valve. That is to install LNG pressure regulating valve on the ball, which can be used to derive LNGin in the blind area after opening and closing of LNG ball valve, so as to achieve the purpose of safely releasing pressure, thus improving the control efficiency of LNG process and the safety of valve, in addition, because LNG pressure regulating valve releases pressure in time, It can reduce the design pressure of valve and system, and improve the safety and reliability of valve and system operation. Finally, according to the low temperature valve design manual and related standards, the structure of LNG ball valve and LNG pressure regulating valve is designed reasonably, and based on the theory of heat transfer, Based on the numerical simulation, the physical model of the long necked bonnet with cooling fin and the LNG pressure regulating valve is studied as follows: 1) the physical model of the long necked valve cap with cold fin is established. Firstly, according to the theory of heat transfer, the thickness of insulation layer of LNG ultra-low temperature ball valve is calculated theoretically and simulated, and then the optimum thickness of insulation layer is obtained by comparing and analyzing the two results. Secondly, the simulation plug-in of Solidworks software is used to simulate the temperature field distribution of the long neck bonnet structure, and the optimum model of the position of the fin and the best model of the number of pieces are obtained. Finally, the optimal structure model of the long neck valve cover and the actual height of the valve neck after adding the distributed cold fin are determined. According to the relevant theory of fluid mechanics, the flow simulation plug-in Solidworks software is used to simulate the flow field of LNG pressure regulating valve, and the flow field temperature is obtained. According to the theory of heat transfer and thermodynamics, the thermo-structural coupling model is used to analyze the thermal stress of the long neck valve cover structural assembly, and the variation of stress, displacement and strain are obtained. The thermal stress analysis of pressure-spring of LNG pressure regulating valve is carried out, and the variation of shear stress and axial displacement is obtained, and the theoretical verification is carried out. Based on the method of theoretical calculation and simulation analysis, this paper analyzes and studies the key problems, such as how to reduce the height of the valve cover of long neck valve and how to release pressure safely, taking LNG cryogenic ball valve as the research object. Some conclusions of practical significance are obtained, which provide references for the development of LNG cryogenic valves.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TE974.3

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