【作者】 王天祥；

【导师】 何利民；

【作者基本信息】 中国石油大学 ， 油气储运工程， 2008， 博士

【摘要】 目前,我国在油气分离方面存在的主要问题一是多相流体中的有用能量被部分或完全消耗;二是当泡沫和乳化产生时,分离不彻底。在天然气处理工艺中主要存在的不足之处是处理过程和气液分离过程分开,工艺复杂,设备多,经济效益低。为了解决上述问题,我国石油工业学者对分离技术进行了不懈的研究,取得了一定的成效,但仍然不能完全解决上述问题。由美国MPPT公司开发的一种集气液分离、天然气处理、输出轴功于一体的小型、高效旋转涡轮分离器彻底解决了上述问题。该分离器具有结构紧凑,分离效率高、工况适应性强、充分利用可用能量等特点。该分离器目前在国外正处于海上平台和陆上油气田的现场试验阶段,并且取得了很好的效果。然而该分离器在内部结构和理论研究等方面都是保密的,因此,有必要对其进行详细的研究。本研究从理论分析、结构设计、数值模拟和试验几方面对旋转涡轮分离器进行了深入系统的研究,该分离器的研究对我国石油工业开发拥有自主知识产权的旋转涡轮分离器以及在气液分离和天然气处理方面有十分重要的理论价值和应用价值。本文主要研究内容和结论如下:以旋转涡轮分离器的基本原理为基础,对旋转涡轮分离器的总体结构进行了初步分析,得到了构成旋转涡轮分离器的基本组成部分:两相喷嘴、分离转子、气液排出装置和轴及其密封、润滑部分。以均匀理论模型和Rudinger等温模型为基础,充分考虑气液两相喷嘴中相问的热传递和拉力等耦合效应以及两相喷嘴的压力、温度等控制流动参数,开发了两相喷嘴设计及参数分析的理论模型——变速度比等温模型和两相耦合模型。通过对两相喷嘴中两相流体可能等温的情况进行理论分析,给出了两相耦合模型可以简化为变速度比等温模型的条件。对上述几种两相喷嘴模型进行了比较,证明了所提出的模型的合理性。开发了两相喷嘴设计及参数分析的计算机程序,用该程序对两相喷嘴进行了初步的参数计算,验证了所提出的两相耦合模型可以对两相喷嘴进行参数分析。通过改变两相喷嘴两相耦合模型中液滴的热传递系数等特性的数值,研究了两相喷嘴效率等性能对液滴特性的敏感性,发现两相喷嘴性能对液滴的破碎敏感性很大,而对热传递系数和拉力等特性敏感性较低。用两相耦合模型在两相喷嘴控制流动参数对两相喷嘴性能的影响方面进行了分析,发现影响两相喷嘴性能的主要控制流动参数为:载荷比(液气质量流量之比)、气体压力、液滴直径和两相的热物理属性等。对液体和气体之间的能量分配进行了计算,发现在一定的操作条件下,随着载荷比的增大,液相所携带的动能增加。在参数分析的基础上,确定了两相喷嘴最优设计和性能标准,两相喷嘴设计标准是根据两相喷嘴的应用场合选择喷嘴的几何形状和长度,以及总体考虑系统的情况设定控制流动参数;喷嘴效率、喷嘴出口处的混合物速度、推力和推力系数是两相涡轮分离器中两相喷嘴的性能标准;但选定喷嘴的性能和设计必须与整个功率提取系统合为一体,以产生最优的总体系统。以Rudinger等温模型为基础,开发了两相喷嘴近似几何参数的快速计算方法。通过计算发现在载荷比小于5时,简化等温两相喷嘴尺寸计算方法计算出的喷嘴直径要比两相耦合模型大。对两相喷嘴的效率等非设计工况性能进行了分析,提出了计算两相喷嘴非设计工况性能的两种模型——两相耦合非设计工况模型和等温非设计工况模型,并进行了比较,比较结果显示两相耦合非设计工况模型在某些工况计算时存在数值计算的不稳定性,而等温非设计工况模型却不存在上述问题。本文用等温非设计工况模型进行了两相喷嘴的非工况分析。发现影响两相喷嘴非设计性能特性的主要流动参数是入口压力、入口温度和载荷比;两相混合物中的两相音速低于单相气体的音速,入口压力和载荷比对出口两相音速和马赫数有较大的影响,而入口温度的影响很小。用Rudinger等温模型、变速度比等温模型和两相耦合模型分别设计了四种两相喷嘴,并进行了CFD数值模拟,将模拟结果与非工况理论计算结果进行了比较,证明了所开发的两相喷嘴理论模型的正确性。将四种喷嘴的数值模拟结果进行了比较,优选出了适合于旋转涡轮分离器的两相喷嘴结构。通过两相喷嘴的试验,验证了两相耦合模型和变速度比等温模型比Rudinger等温模型更能反映两相喷嘴中的实际流动情况。在两相喷嘴研究的基础上,对旋转涡轮分离器的结构进行了详细的设计计算,得到了组成分离器的构件:分离表面、分离轮、气液排出装置等,设计计算了用于增加输出轴功的气液反作用喷嘴、气体反作用叶轮等结构。对分离器的旋转速度、分离表面上液滴的运动进行了系统的理论分析,并对其中的一部分结构进行了简单的数值模拟定性分析,这些数值模拟结果可以指导分离器结构的设计优化。对分离器的密封系统、轴及轴承系统进行了设计和校核。完成了旋转涡轮分离器的设计,并成功制造了试验样机。对分离器样机进行了室内试验研究,发现影响分离效率及其轴功输出能力的主要因素是分离器的转速。对分离器的结构进行了评估。对所设计喷嘴两相流动中的相变进行了数值模拟,进而对分离器在天然气脱水方面进行了探索研究。更多还原

【Abstract】 At present, the main problems existing in civil gas/liquid separation system are: useful energy is completely or partly consumed in multiphase flow and, secondly, separation is not thorough when froth and emulsification produce. The main deficiencies in natural gas processing are the separation of treating process and gas/fluid separating, the complexity of process, too many equipments and low economic efficiency. In order to solve the above problems, civil scholars working in oil industry has been doing unremitting research in isolation technique and made certain progress, but still could not solve the problem completely. One kind of midget highly efficient revolving turbine separator, which gathers gas/liquid separation and natural gas processing and shaft merit output in one body, is developed by American MPPT Corporation to solve the problems completely. The separator has some advantages, such as compact structure, high separating efficiency, strong compatibility and full use of available energy, etc.. At abroad, the separator is being tested in the offshore platform and land oil-gas field at present and good progress is made. However, the internal structure of separator and relative fundamental research is secret. Therefore, it is necessary to conduct the detailed research on it. The paper conducts a thorough systematic research on revolving turbine separator in forms of theoretical analysis, structural design, numerical simulation and experiment. The research of the separator has very important theory and application value in gas/liquid separation and natural gas process, and for that civil oil industry possesses the proprietary intellectual property rights of revolving turbine separator as well. The main contents and conclusions of the research are as follows:Based on the basic principle of the rotary turbine separator, the overall structure of a rotary turbine separator is preliminary analyzed. It includes several basic components: two-phase nozzle, separating rotor, gas & liquid exports, axle, sealed and lubricated part.Based on the two-phase nozzle theoretical models, i.e. uniform theoretical model and Rudinger isothermal model, variable velocity ratio isothermal model and the droplet Two-phase fluid coupling model used for two-phase nozzle design and parametric analysis are studied in this paper, in which the coupling effect between gas and liquid in the nozzle as well as controlling flow parameters are fully considered. The possible condition that fluids in the nozzle are in the same temperature is theoretically analysed. The condition for the droplet Two-phase fluid coupling model can be simplified as variable velocity ratio isothermal model is presented. The two-phase nozzle models are comparisiond and the droplet Two- phase fluid coupling model is proved to be reasonable. A program for two-phase nozzle design and parametric analysis is compiled and preliminary parametric calculation is done .By changing the value of some droplet characters in the two-phase nozzle model, the sensitivity of nozzle performance on the characters of droplet is studied. The effect of two-phase nozzle’s parameters to its performance is analyzed through droplet Two- phase fluid coupling model. And the energy distribution between gas and liquid is estimated. According to the parameter analysis, the standard for optimal nozzle design and performance is determined. A method for rapid design of approximate nozzle geometric parameter is developed on the basis of Rudinger isothermal theory.The performance of two-phase nozzle off-design is analyzed. And two models calculating the performances of two-phase nozzle under off-design work conditions are presented and comparisiond, i.e. the heat transfer off-design work conditions model and the isothermal off-design work conditions model. For two-phase nozzle given the geometric parameters, the relationships of load ratio, inlet pressure and temperature, mass flow of gas fluid and efficiency of the nozzle are studied in the paper. The relative contents also include the influence of heat transfer to nozzle performance and the factors influencing two-phase Mach number and velocity of sound.Based on Rudinger isothermal model, variable velocity ratio isothermal model and the droplet Two-phase fluid coupling model, four two-phase nozzles are designed. And numerical simulation is done using Fluent. The simulation results and theoretical results under off-design work conditions are comparisiond and proved the correctness of the theory. The numerical simulation results of four nozzles are comparisiond and the two-phase nozzle fit for rotating turbine separator is selected. Two-phase nozzle theory is further verified through experiments.According to the research of two-phase nozzle, the detailed structure of rotary turbine separator is designed. The rotary turbine separator includes: the surface of separation, separation wheel, gas & liquid discharging devices etc., the gas-liquid reaction nozzle which can increase the output shaft power, the gas reacting impeller, etc.. The rotational speed of separator and the motion of droplet on the separation surface are systematically analyzed. And qualitative analysis of part of them is done by simple numerical simulation. The simulation results can guide the optimal design of the separator structure. The sealing system, shaft and bearing system of the separator are designed and verified. The design of rotating turbine separator is completed and experimental prototype is manufactured.A simple laboratory experiment of separator prototype is done. The main factors influencing rotaryspeed of separator, output of shaft power and separation efficiency are analysed in this paper, and thestructure of the separator is assessed.Numerical simulation of the phase change of two-phase flow in the designed nozzle is finished using Fluent, and the application of the separator in the area of gas dehydration is initially studied.更多还原