液化天然气潜液泵的水力设计研究及其样机研发

发布时间：2018-02-02 02:37

本文关键词： LNG潜液泵诱导轮导叶 CFD 低温液体空化　出处：《上海大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来,清洁能源液化天然气(LNG)在世界能源供应中的比例迅速增加,成为全球增长最迅猛的石油化工产品之一。LNG在整个产业链中的转移需要借助液化天然气(LNG)潜液泵来实现。目前,国外几家公司基本垄断着LNG潜液泵的供应,若自主研制LNG潜液泵,则必须先对LNG潜液泵的设计进行研究。本文以LNG加注站装置中的LNG潜液泵为具体研究对象,在把握其结构特点的基础上,分析、研究并总结设计方法,研制LNG潜液泵样机,旨在为今后LNG潜液泵的设计制造提供理论基础和技术支撑。全文的主要工作如下:一、LNG潜液泵主要过流部件的水力设计研究这部分重点分析和研究叶轮、诱导轮和导叶等主要过流部件的水力设计方法,兼顾泵的性能及结构合理性,对叶轮、诱导轮、导叶进行水力设计。叶轮设计采用基于一元设计理论的传统设计方法,针对LNG潜液泵的特点,考虑液体流经出液管段的水力损失来计算理论扬程,以保证泵整机的扬程。诱导轮的设计扬程需根据叶轮的必需汽蚀余量来确定。考虑到计算流体动力学(CFD)方法可以仿真泵内的空化流动,本文通过数值实验方法来确定叶轮的必需汽蚀余量,并综合考虑性能的要求和结构的合理性,确定诱导轮的几何参数。导叶采用了一种特殊的结构,其优点是可有效减小泵的径向尺寸。由于这种导叶尚无确定的设计方法,本文借鉴径向导叶的设计方法,确定LNG潜液泵导叶的几何参数,并通过数值方法研究导叶进口喉部宽度和折转角对泵水力性能的影响,发现进口喉部宽度对泵扬程和效率影响较大,且存在最优值,而进口折转角对泵扬程和效率则影响较小。二、LNG潜液泵水力性能和空化性能预测本文在水力设计完成后,通过数值模拟的方法预测泵的水力和空化性能,并对泵内的流动和空化特征进行分析。水力性能预测时,将LNG潜液泵的所有过流区域作为计算域,在不同流量下计算LNG潜液泵的性能参数;空化性能预测时,计算域则主要包括诱导轮和一级叶轮的过流部分,分别在等温和考虑热力学效应情况下进行空化数值模拟,分析热力学效应对低温空化的影响。结果表明:预测的潜液泵水力性能可以达到设计要求,流量-扬程曲线在小流量工况较为平坦,大流量工况下降较快,且泵的高效率区较宽。低温液体热力学效应对泵的空化性能影响显著,考虑热力学效应计算的泵必需汽蚀余量比等温情况下计算的值要小。三、LNG潜液泵样机研制及试验在LNG潜液泵样机设计的基础上,研制LNG潜液泵样机,以液氮为介质,分别针对现有相同设计参数的进口LNG潜液泵和新研制的LNG潜液泵进行性能试验。试验结果表明新研制的LNG潜液泵运行正常,其效率在小流量工况时低于进口泵,大流量时高于进口泵,且高效率区更宽,这将有利于该泵的实际应用。
[Abstract]:In recent years, the proportion of clean energy, liquefied natural gas (LNG) in the world energy supply has increased rapidly. To become one of the fastest growing petrochemical products in the world. The transfer of LNG in the whole industry chain needs to be realized by means of liquefied natural gas (LNG) submersible pump. Several foreign companies basically monopolize the supply of LNG submersible pumps, if we develop LNG submersible pumps independently. The design of the LNG submersible pump must be studied first. This paper takes the LNG submersible pump in the LNG filling station as the specific research object, and analyzes it on the basis of grasping its structural characteristics. This paper studies and summarizes the design method and develops the prototype of LNG submersible pump in order to provide the theoretical foundation and technical support for the design and manufacture of LNG submersible pump in the future. The main work of this paper is as follows: 1. Study on hydraulic Design of main Over-flow parts of LNG submersible pump; this part focuses on the hydraulic design methods of impeller, induction wheel and guide vane, taking into account the performance and structural rationality of the pump, and the impeller. The impeller design adopts the traditional design method based on the univariate design theory, according to the characteristics of LNG submersible pump, considering the hydraulic loss of liquid flowing through the outlet pipe to calculate the theoretical head. In order to ensure the head of the whole pump, the design head of the induction wheel should be determined according to the necessary cavitation allowance of the impeller. Considering the computational fluid dynamics (CFD) method, the cavitation flow in the pump can be simulated. In this paper, the necessary cavitation allowance of impeller is determined by numerical experiment method, and the geometric parameters of induction wheel are determined by considering the requirements of performance and the rationality of structure. The guide vane adopts a special structure. The advantages are that the radial dimension of the pump can be reduced effectively. As there is no definite design method for the guide vane, the geometric parameters of the guide vane of the LNG submersible pump are determined by using the design method of the diameter-guide vane. The influence of inlet throat width and angle of guide vane on the hydraulic performance of the pump is studied by numerical method. It is found that the inlet throat width has great influence on the head and efficiency of the pump, and there is an optimum value. The hydraulic performance and cavitation performance of LNG submersible pump are predicted by numerical simulation after the completion of hydraulic design. The flow and cavitation characteristics in the pump are analyzed. When the hydraulic performance is predicted, the performance parameters of the LNG submersible pump are calculated under different flow rates by taking all the flow areas of the submersible pump as the computational domain. In the prediction of cavitation performance, the numerical simulation of cavitation is carried out in the case of isothermal consideration of thermodynamic effect, which mainly includes the overflowing part of the induction wheel and the first stage impeller. The effect of thermodynamic effect on cavitation at low temperature is analyzed. The results show that the hydraulic performance of the submersible pump can meet the design requirements, the flow-head curve is flat in the small flow condition, and the large flow condition decreases rapidly. The thermodynamic effect of low temperature liquid has a significant effect on the cavitation performance of the pump, and the necessary cavitation allowance calculated by considering the thermodynamic effect is smaller than that calculated under isothermal condition. Development and test of LNG submersible pump prototype on the basis of LNG submersible pump prototype, the prototype of LNG submersible pump is developed, in which liquid nitrogen is used as the medium. The performance tests of the imported LNG submersible pump and the newly developed LNG submersible pump with the same design parameters have been carried out respectively. The test results show that the newly developed LNG submersible pump is running normally. The efficiency of the pump is lower than that of the imported pump in the small flow condition, and higher than that of the inlet pump in the large flow rate, and the high efficiency zone is wider, which will be beneficial to the practical application of the pump.
【学位授予单位】：上海大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE974.1

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