水合物防聚剂多相流管线中初步应用技术研究

本文围绕新型水合物化学抑制剂（防聚剂）在海上油气田现场应用过程中将遇到的管道输送工艺设计技术问题开展研究。首次以海上凝析油气田现场采集的油、水和按天然气组分配置的气体为实验介质,加入国内自主研制的水合物防聚剂,在水平透明实验环道上进行了水合物浆液流动压降实验。通过分析实验结果并借助液固两相流有关理论,初步建立了水合物浆...     

多相混输管道水合物预测及控制动态试验研究

应用轮式流动模拟器可以模拟多相混输管道的生产实际工况,通过监测流动模拟器转轮的扭距、转速、试验介质的温度、压力参数的变化,并结合直接观测的手段,综合进行水合物动态模拟试验.建立了水合物生成预测方法、水合物生长规律及动力学抑制效果试验研究方法,应用这些方法可以进行混输管道中的水合物生成条件预测试验、水合物热力学抑制效果试验及水合物动力学抑制效果试验,为混输管道的设计和正常生产运行提供技术依据.     

纳米流体中气体水合物生成条件

为了研究纳米粒子对制冷剂水合物热力学生成条件的影响,建立了新型纳米流体中制冷剂水合物相平衡热力学模型,理论研究了HFC134a(R134a)气体水合物的热力学生成条件,并用实验验证了模拟结果.结果表明:新型纳米流体中制冷剂水合物热力学相平衡模型能够较好地反映纳米流体中制冷剂气体水合物相平衡特征,相同温度下相平衡最大相对误差为7.3%,平均相对误差为5.3%.     

水合物封闭升温及降压分解气液迁移特性

水合物分解过程产生的气液固迁移特性是影响水合物分解速率的关键要素。基于此,搭建了一套可视化的水合物生长及分解特性研究实验系统,通过该系统对封闭升温及降压分解过程中气液迁移特性进行了研究。实验结果表明,水合物在封闭升温分解过程中的气液迁移主要是通过形成气体通道实现的;同时,水合物分解过程中的气液迁移会造成沉积物的体积膨胀,在封闭升温分解过程中,沉积物体积膨胀率随着分解次数的增加而增加,三次分解膨胀率依次为18. 7%,34. 7%和45. 4%。背压为0. 1 MPa的降压分解中,体积膨胀率为64. 7%,温度迅速下降,并伴随着冰的生成或水合物的再次生成阻碍分解,但是降压依然加速了水合物的分解,使得水合物的总分解速率相对于封闭升温分解提高了20. 5%。实验结果对水合物技术应用具有理论和数据支撑作用。     

海上平台水合物分离器内气液两相流数值模拟

针对海上平台的特点,提出了海上平台水合物分离器工作原理及结构设计,该装置无需要添加任何化学药物,高效地从天然气中分离出水和重烃类液体,同时具有节能环保,结构紧凑,占地面积小和分离效率高等优点。同时,基于严谨的多相流体动力学理论,采用计算流体力学(CFD)对水合物分离器内气液两相流进行了三维非稳态数值模拟。模拟计算结果表明,所采用的数学模型和数学模拟计算方法正确,可以预测并反映不同时刻分离器中气液两相体积比率的变化规律,从而更加系统深入地探讨了水合物分离器内气液两相的流动及分离特性,从两相流的角度对水合物分离器的结构优化提供了理论根据。     

储氢笼型水合物生成促进机理的分子动力学模拟研究

用分子动力学(MD)模拟方法研究水合物法储氢的促进机理,系统研究纯H₂水合物、H₂+四氢呋喃(THF)水合物、H₂+四丁基溴化铵(TBAB)半笼型水合物和H₂+四异戊基溴化铵(TiAAB)半笼型水合物的微观结构及性质.模拟分析客体与笼子之间的稳定能ΔE_GH,得出水合物中大笼子对稳定水合物起到主要作用.THF进入大笼子能促进H₂水合物稳定,降低H₂水合物形成压力,模拟结果与实验一致.模拟对比不同客体在大笼子中的ΔE_GH值,得出从小到大的顺序依次为TiAAB,TBAB,THF,H₂.模拟结果表明半笼型水合物的稳定性比结构Ⅱ型水合物强,同时得出H₂+TiAAB半笼型水合物的结构最稳定.MD模拟为TiAAB成为一种水合物新型促进剂和新型储氢材料提供了理论依据. 关键词： 2笼型水合物')" href="#">H₂笼型水合物 分子动力学模拟 储氢 半笼型水合物     

醇类抑制剂对甲烷水合物形成的影响

在本工作中,甲烷水合物的生长动力学是通过甲醇、乙醇、乙二醇三种不同醇类抑制剂存在下的分子动力学模拟研究的.模拟结果发现,三种醇类都可作为甲烷水合物的抑制剂,醇类分子中的亲水性羟基极大地破坏了水合物笼的结构,并且羟基可以与局部的液态水分子形成氢键,从而增加了形成水合物笼型结构的难度,导致甲烷水合物的生长速率降低.对于甲醇分子,甲醇分子的亲水性羟基与水分子形成氢键从而破坏了水分子结构,而亲油性甲基对周围的水分子具有簇效应,两者都会降低水合物生长速率;对于乙二醇和乙醇分子,它们只含有羟基,特别是乙二醇分子含有两个羟基,其对H₂O分子有很强的吸附作用,导致水合物生长速率降低.在抑制效果方面,甲醇分子最优,乙二醇稍微优于乙醇.     

帕拉米韦三水合物的拉曼光谱计算与分析

为了提供基于拉曼光谱鉴定帕拉米韦三水合物的需要,本文通过微区拉曼光谱仪检测了帕拉米韦三水合物标准化学对照品的自然拉曼光谱,利用密度泛函方法计算了两种帕拉米韦三水合物同分异构体的理论拉曼光谱。提出了特征频率取样的拉曼光谱识别函数,并根据实验结论对理论光谱进行校正,得到了与实验匹配度较高的帕拉米韦三水合物的理论拉曼光谱。最后分析了实测光谱特征峰位的振动模式。     

高压CO2水合物的生成机理实验和模拟

温室气体CO_2的捕捉和储存对减缓温室效应具有重大意义。CO_2水合物法储存CO_2具有效率高、储量大、易运输等优点。为了更高效制备CO_2水合物,对其生成机理进行实验和模拟研究。通过建立水合物生成的热力学模型,对水合物生成条件进行预测,利用高压静态釜式反应容器开展水合物生成实验,通过温度压力数据验证模型的准确性。在选取化学势能差作为水合物生成驱动力的基础上建立气体消耗速率模型,并与实验结果对比,结果表明:模型的预测值与实验值相对吻合。在低于水合物相平衡温度的条件下,升高容器的内反应压力可以促进气-液质量交换过程,提高生成效率。在生成过程中测得不同位置的电阻率变化数据,发现容器内的电阻率随固态水合物的生成而升高,并且首先在容器上部靠近壁面处结晶、团聚。     

显微激光拉曼光谱原位观测甲烷水合物生成与分解的微观过程

采用显微激光拉曼光谱技术对高压透明毛细管中甲烷水合物的生成与分解的微观过程进行了原位观测,初步探讨了甲烷水合物笼型结构的变化规律.结果表明,甲烷水合物在生成过程中,甲烷分子的拉曼峰(2 917 cm-1)逐渐分裂为两个峰(2 905和2 915 cm-1),表明溶解态甲烷分子从单一的化学环境进入了两个有差异的化学环境中...     

海面甚薄油膜光谱响应研究与分析

海面甚薄油膜存在着特定的光谱响应,文章通过模拟海面甚薄油膜随其厚度的变化过程,研究其高光谱响应特征与产生机理.甚薄油膜随着厚度从大到小的逐渐变化,表现为六种目视特征:彩虹亮油膜、品色亮油膜、黄绿亮油膜、浅绿亮油膜、银色亮油膜与几乎不可见油膜.分析六种状态下海面甚薄油膜的光谱反射率表明:350～540 nm甚薄油膜的反射差异明显,甚至可以影响到440 nm处叶绿素的吸收峰;350～900 nm范围内,甚薄油膜的反射光谱普遍高于海水的反射光谱,但540～900 nm范围内缺乏明显的吸收反射特征;在近红外920～2 500 nm范围内没有明显的光谱响应.结合海面甚薄油膜光谱响应特征分析,指出海面甚薄油膜存在平行多光束干涉现象,入射到薄膜内的光由于多次反射和折射导致了海面可见光/近红外光谱反射率的增加,为海面甚薄油膜遥感探测提供了理论依据.     

Coolant choice for the central beryllium pipe of the BESⅢ beam pipe

In order to take away much more heat on the BESⅢ beam pipe to guarantee the normal particle detection,EDM-1(oil No.1 for electric discharge machining),with good thermal and flow properties was selected as the candidate coolant for the central beryllium pipe of the BESⅢ beam pipe.Its cooling character was studied and dynamic corrosion experiment was undertaken to examine its corrosion on beryllium.The experiment results show that EDM-1 would corrode the beryllium 19.9 μm in the depth in 10 years,which is weak and can be neglected.Finite element simulation and experiment research were taken to check the cooling capacity of EDM-1.The results show that EDM-1 can meet the cooling requirement of the central beryllium pipe.Now EDM-1 is being used to cool the central beryllium pipe of the BESⅢ beam pipe.     

基于湍流振动的光纤干涉仪流量计的研究

针对石油测井中流量是确定石油生产和传输特性极其重要的参数,提出一种非浸入式光纤干涉仪流量测量方法。在油管外壁紧密缠绕传感光纤,当流体流过管壁时可由湍流产生振动,引起管壁的动态压力变化,导致传感光纤内的传输光相位发生变化, 通过检测光相位的变化就可以获得相应的流量。在实验中找出管壁的振动频率特性,在此频率特性范围内确定出由湍流诱发的管壁振动加速度脉动值的标准方差与平均流量的量化关系,实现了5 m3/h~50 m3/h流量实时在线测量。     

Time domain identification of standing wave parameters in gas piping systems

A method for experimentally determining the natural frequencies and modal pressures of an air or gas piping system is presented. Such information is of interest in installations where pressure pulsations caused by pumps or compressors are of importance. In the method a time domain based technique is used which was originally developed as an alternative to frequency response methods for determining the vibration parameters (natural frequencies, modes, damping factors) of structures, to avoid difficulties often encountered in interpreting complex and non-conclusive frequency response data such as arises from systems having numerous modes, some of which may be highly damped or closely spaced in frequency. In this application, a straight steel pipe with a sound source at one end and closed at the other end was used. Two microphones were used to measure the pressure at two locations in the pipe. The free pressure response following a rapidly swept sinewave input was recorded, digitized and then used in a computational procedure based on a lumped parameter representation of the system. The natural frequencies and the corresponding modal pressure ratios at the two stations, thus obtained, are compared with mention here that although in the experiment reported here an external frequency sweep excitation was used, the technique works as well with free decay response after a system shut-off, impulse response or random responses from normal system operation.     

Theoretical and Experimental Investigation of Flexural Vibration Transfer Properties of High-Pressure Periodic Pipe

According to the theory of phononic crystals,the hydraulic pipeline is designed to be a periodic structure composed of steel pipes and hoses to suppress the vibration of the hydraulic system with band gaps.We present theoretical and experimental investigations into the flexural vibration transfer properties of a high-pressure periodic pipe with the force on the inner pipe wall by oil pressure taken into consideration.The results show that the vibration attenuation of periodic pipe decreases along with the elevation of working pressure for the hydraulic system,and the band gaps in low frequency ranges move towards high frequency ranges.The periodic pipe has good vibration attenuation performance in the frequency range below 1000 Hz and the vibration of the hydrauhc system is effectively suppressed.All the results are validated by experiment.The experimental results show a good agreement with the numerical calculations,thus the flexural vibration transfer properties of the highpressure periodic pipe can be precisely calculated by taking the Quid structure interaction between the pipe and oil into consideration.This study provides an effective way for the vibration control of the hydraulic system.     

垂直管内油水两相流局部相分布特性实验研究

应用双头电导探针测量系统,对垂直上升管内油水两相分散流局部相分布特性进行了系统测量。得到了油水两相分散流的局部含油率分布类型图。研究结果表明低折算水速和低折算油速条件下,局部含油率在实验段截面上呈抛物线型局部分布特征,局部最大值出现在实验段中心区域。随折算油速增大,油滴受到横向力如升力的作用,逐渐向实验段壁面区域迁移,形成局部含油率的壁面峰值分布特性。当折算水速大于0．8 m／s时,局部含油率在实验段截面上呈均匀分布。     

Numerical modelling of acoustic pressure fields to optimize the ultrasonic cleaning technique for cylinders

Fouling build up is a well-known problem in the offshore industry. Accumulation of fouling occurs in different structures, e.g. offshore pipes, ship hulls, floating production platforms. The type of fouling that accumulates is dependent on environmental conditions surrounding the structure itself. Current methods deployed for fouling removal span across hydraulic, chemical and manual, all sharing the common disadvantage of necessitating halting production for the cleaning process to commence. Conventionally, ultrasound is used in ultrasonic baths to clean a submerged component by the generation and implosion of cavitation bubbles on the fouled surface; this method is particularly used in Reverse Osmosis applications. However, this requires the submersion of the fouled structure and thus may require a halt to production. Large fouled structures such as pipelines may not be accommodated. The application of high power ultrasonics is proposed in this work as a means to remove fouling on a structure whilst in operation. The work presented in this paper consists of the development of a finite element analysis model based on successful cleaning results from a pipe fouled with calcite on the inner pipe wall. A Polytec 3D Laser Doppler Vibrometer was used in this investigation to study the fouling removal process. Results show the potential of high power ultrasonics for fouling removal in pipe structures from the wave propagation across the structure under excitation, and are used to validate a COMSOL model to determine cleaning patterns based on pressure and displacement distributions for future transducer array design and optimization.     

Pipe wall damage detection by electromagnetic acoustic transducer generated guided waves in absence of defect signals

Most investigators emphasize the importance of detecting the reflected signal from the defect to determine if the pipe wall has any damage and to predict the damage location. However, often the small signal from the defect is hidden behind the other arriving wave modes and signal noise. To overcome the difficulties associated with the identification of the small defect signal in the time history plots, in this paper the time history is analyzed well after the arrival of the first defect signal, and after different wave modes have propagated multiple times through the pipe. It is shown that the defective pipe can be clearly identified by analyzing these late arriving diffuse ultrasonic signals. Multiple reflections and scattering of the propagating wave modes by the defect and pipe ends do not hamper the defect detection capability; on the contrary, it apparently stabilizes the signal and makes it easier to distinguish the defective pipe from the defect-free pipe. This paper also highlights difficulties associated with the interpretation of the recorded time histories due to mode conversion by the defect. The design of electro-magnetic acoustic transducers used to generate and receive the guided waves in the pipe is briefly described in the paper.     

真空隔热油管接箍传热实验与模拟研究

真空隔热油管井筒的传热计算是稠油开采领域的重要研究课题.注蒸汽采油井筒内,隔热油管是靠接箍连接在一起的,接箍虽然很短,但其隔热性能较差.目前,隔热油管接箍段引起的散热损失均按经验比例计算,本文对隔热油管接箍的传热进行了深入研究,提出用接箍视导热系数来衡量接箍的隔热性能.并通过现场实验、fluent模拟和理论计算相结合的方法,得到带衬套的接箍视导热系数为0.4 W/(m·K)左右.在实验条件下,接箍散热损失占总散热损失的比例大于1/3.因此,应采用必要措施提高接箍的隔热性能,以保证整个隔热油管的隔热效果.