發(fā)布時間：2018-03-16 10:10

  本文選題：天然氣長輸管道　切入點：閥室　出處：《西南石油大學》2015年碩士論文　論文類型：學位論文

【摘要】：隨著國家經(jīng)濟快速發(fā)展,對天然氣的需求量逐年增加,但考慮到天然氣資源分布不均的情況,我國石油公司修建了大量的天然氣長輸管道。閥室在天然氣長輸管道系統(tǒng)中具有重要作用,當管道出現(xiàn)事故或需要改造時,需要利用閥室截斷來氣,并放空特定管段內(nèi)天然氣,以保證維修維護操作能夠安全地進行。我國天然氣管道閥室數(shù)量較多,所處地形多種多樣,影響閥室放空作業(yè)的外部因素復雜多變,加上長輸管道內(nèi)的天然氣本身具有高壓、易燃易爆等特性,由立管直接排放天然氣的過程具有一定風險。在近幾年的天然氣長輸管道放空作業(yè)中,由于放空方式不當和障礙物的影響等導致了一些放空事故的發(fā)生,造成了巨大的經(jīng)濟損失,威脅到相關人員的生命安全,并給周邊環(huán)境帶來了污染和破壞。 論文利用故障樹分析原理,識別了閥室冷放空主要危害,通過對故障樹的定性和定量分析,找出閥室冷放空過程中與“人—機—環(huán)境”有關的風險。運用流體力學、射流力學等理論分析了氣體擴散主要影響因素,并分別確定了計劃性和事故性放空量的計算方法。分別考慮有/無障礙物兩種環(huán)境情況,建立了天然氣冷放空物理模型；運用PHAST軟件和FLUENT軟件進行數(shù)值模擬,定性和定量地分析了風速、大氣穩(wěn)定度、初始出口壓力、出口直徑以及障礙物情況等變量對擴散過程和范圍的影響規(guī)律,劃分出不同工況下放空時氣體擴散危險區(qū)域。運用HYSYS軟件計算了不同壓力和溫度條件下放空閥處的溫降大小,分析了溫降效應對放空閥性能的影響；計算了作業(yè)過程中立管出口位置氣體動能增加引起的氣體焓降低量,分析了氣體與管壁的對流換熱引起的放空立管處的低溫效應。最后,在所得結(jié)果的基礎上提出了相關的風險控制措施。 論文得到的氣體擴散的數(shù)值模擬結(jié)果與氣體擴散理論相符,并且與放空現(xiàn)場實測數(shù)據(jù)的偏差在可接受的范圍內(nèi),對于放空閥和放空立管處的溫降計算結(jié)果能較好解釋閥室冷放空作業(yè)現(xiàn)場出現(xiàn)的相關現(xiàn)象。研究成果具有較好的工程實用價值,對天然氣長輸管道閥室冷放空作業(yè)的風險控制和后果預測具有一定指導意義。
[Abstract]:With the rapid development of the national economy, the demand for natural gas has increased year by year, but considering the uneven distribution of natural gas resources, The valve chamber plays an important role in the long distance natural gas pipeline system. When the pipeline happens or needs to be reformed, it is necessary to use the valve chamber to cut off the gas and empty the natural gas in the specific section. In order to ensure that the maintenance and maintenance operation can be carried out safely, the number of valve chambers in natural gas pipelines in China is relatively large, the topography is varied, the external factors affecting the emptying of valve chambers are complex and changeable, and the natural gas in the long distance pipeline has high pressure. The process of discharging natural gas directly from riser has certain risks due to the characteristics of flammability and explosive. In recent years, during the long distance pipeline emptying operation, some emptying accidents occurred due to improper emptying mode and the influence of obstacles, etc. It has caused huge economic losses, threatened the safety of the relevant personnel, and brought pollution and damage to the surrounding environment. Based on the principle of fault tree analysis, this paper identifies the main hazards of cold emptying in valve chamber. By qualitative and quantitative analysis of fault tree, the risks related to "man-machine-environment" in cold emptying process of valve chamber are found out. The main influencing factors of gas diffusion are analyzed in the theory of jet mechanics, and the calculation methods of planned and accidental emptying are determined respectively. The physical model of natural gas cold emptying is established by considering the two kinds of environmental conditions with or without obstacles. The effects of wind speed, atmospheric stability, initial outlet pressure, outlet diameter and obstacle on the diffusion process and range are analyzed qualitatively and quantitatively by using PHAST and FLUENT software. The dangerous area of gas diffusion under different conditions is divided. The temperature drop of the valve under different pressure and temperature is calculated by using HYSYS software, and the effect of temperature drop on the performance of the valve is analyzed. The gas enthalpy decrease caused by the increase of gas kinetic energy at the exit position of riser during operation is calculated, and the low temperature effect at emptying riser caused by convection heat transfer between gas and tube wall is analyzed. On the basis of the obtained results, the related risk control measures are proposed. The numerical simulation results of gas diffusion obtained in this paper are consistent with the gas diffusion theory, and the deviation from the field measured data is acceptable. For the temperature drop calculation results of the emptying valve and the emptying riser, the related phenomena in the cold emptying operation field of the valve chamber can be better explained. The research results have good engineering practical value. It has certain guiding significance for risk control and consequence prediction of valve chamber cold emptying operation in long distance natural gas pipeline.
【學位授予單位】：西南石油大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE88

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本文編號：1619453