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  本文關(guān)鍵詞： 濕天然氣 積液 臨界流速 持液率 數(shù)值模擬　出處：《西安石油大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：在天然氣運輸過程中,由于沿線地形起伏以及溫度、壓力的變化,會在起伏天然氣管道底部彎頭內(nèi)形成積液。積液的存在影響著整個集輸管線的安全、高效運行。而日益增長的燃氣消費需求,對于濕氣管線安全、高效的運輸提出挑戰(zhàn)。彎頭中的積液被驅(qū)離彎頭最重要的方法就是提高氣體的入口速度,所以為保證輸氣管線安全高效的運行,從而研究濕氣管道底部彎頭積液被驅(qū)離平鋪至上傾管段的臨界狀態(tài)以及臨界流速意義重大。本文基于流體力學(xué)基本原理和流體運動基本控制方程,結(jié)合相關(guān)的低含液率氣液兩相流的理論知識,運用CFD軟件FLUENT對濕天然氣管道底部彎頭積液被驅(qū)離至上傾管段的入口臨界流速進行了數(shù)值模擬。分別研究了臨界狀態(tài)時不同積液量、不同管路傾角下,臨界狀態(tài)時的臨界管路壓降、臨界持液率以及臨界上傾段液膜平鋪長度的變化規(guī)律;積液被驅(qū)離時的速度場分布以及臨界狀態(tài)時的氣液相界面形態(tài);同時研究了管路積液量、管路傾角、管路直徑、積液粘度四個因素對臨界速度的影響曲線。模擬結(jié)果表明:在臨界狀態(tài)時,液體層幾乎平鋪于上傾管段,但其平鋪厚度并非完全均勻等厚,而是在液體層沿著管道方向兩端相對較薄;臨界流速下,上傾段液體層并未出現(xiàn)明顯的回流跡象;臨界狀態(tài)下,氣液的界面形態(tài)與TaitelDuekler提出的FLAT模型較為吻合;臨界狀態(tài)時持液率基本保持恒定,這點驗證了積液在上傾段基本均勻等厚的理論;臨界壓降與積液量的大小并無直接關(guān)系,但隨著管路傾角的增加也隨著增加;臨界流速隨著管路傾角增大而增大、隨著管路直徑增大而增大、隨著積液量緩慢增加,隨著積液粘度增大而增大。本文研究結(jié)果對防止起伏管道的積液形成具有一定的指導(dǎo)意義,同時有助于明確濕天然氣管道底部彎頭積液被驅(qū)離的機理,為濕天然氣管道設(shè)計和施工提供了必要的理論依據(jù)。
[Abstract]:In the process of natural gas transportation, due to the topographic fluctuation along the road and the change of temperature and pressure, the accumulated fluid will form in the bottom bend of the undulating natural gas pipeline, and the existence of the accumulated liquid will affect the safety of the whole gathering and transportation pipeline. Efficient operation. And the increasing demand for gas consumption poses a challenge to the safe and efficient transportation of wet gas pipelines. The most important way to drive the accumulated liquid from the elbow is to improve the gas inlet speed. It is considered to ensure the safe and efficient operation of the gas pipeline. Therefore, it is of great significance to study the critical state and critical velocity of fluid from the bottom bend of wet gas pipeline. This paper is based on the basic principles of fluid mechanics and the basic governing equation of fluid motion. Combined with the relevant theoretical knowledge of gas-liquid two-phase flow with low liquid fraction. CFD software FLUENT is used to simulate the inlet critical velocity of the bottom bend of wet natural gas pipeline which is driven away from the upper section of the pipe, and the different amount of fluid accumulation is studied respectively in the critical state. The variation law of critical pipe pressure drop, critical liquid holdup and liquid film flattening length at critical state under different pipe inclination angles; The velocity field distribution and the interface morphology of gas and liquid phase at critical state; At the same time, the influence curves of four factors on the critical velocity, such as the amount of fluid accumulated in the pipeline, the inclination angle, the diameter of the pipe and the viscosity of the fluid are studied. The simulation results show that the liquid layer is almost flat in the updip section in the critical state. However, the flat thickness is not uniform and equal thickness, but the liquid layer is relatively thin along the direction of the pipe. At the critical flow rate, there is no obvious sign of reflux in the liquid layer of the updip section. At the critical state, the gas-liquid interface morphology is in good agreement with the FLAT model proposed by TaitelDuekler. At the critical state, the liquid holdup is basically kept constant, which verifies the theory that the liquid accumulated in the updip section is basically homogeneous and equal thickness. The critical pressure drop has no direct relationship with the amount of fluid accumulated, but with the increase of pipe inclination, it also increases with the increase of pipe inclination. The critical velocity increases with the increase of pipe inclination angle, increases with the increase of pipe diameter, and increases slowly with the amount of fluid accumulated. The results of this paper have a certain guiding significance to prevent the formation of fluid accumulation in the undulating pipeline and help to clarify the mechanism of the exorction of the accumulated fluid at the bottom of the wet natural gas pipeline. It provides the necessary theoretical basis for the design and construction of wet natural gas pipeline.
【學(xué)位授予單位】：西安石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TE863

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