疏水管道温度计算方法及其在阀门泄漏诊断中的应用

发布时间：2018-03-13 10:51

本文选题：蒸汽疏水阀门　切入点：泄漏　出处：《长沙理工大学》2014年硕士论文　论文类型：学位论文

【摘要】：火电厂阀门泄漏将会降低整个发电机组的整体效率,甚至可能会直接威胁人员安全和机组运行的安全性。目前,诊断阀门泄漏的方法很多,但是这些方法都有一定的局限性,在火电厂复杂的环境中很难诊断出阀门的早期泄漏故障。因此,基于疏水管道温度场研究阀门泄漏故障具有重要的理论价值和良好的工程应用前景。当阀门发生泄漏时,阀前管壁温度也会相应的变化,因而阀前管壁温度可以用来作为检测阀门是否发生泄漏的诊断特征参数。本文采用理论分析、数值模拟和工程实例验证相结合的方法,对基于疏水管道温度场分布检测的检漏方法进行了研究分析,从而得出火电厂疏水阀门泄漏检测新方法。首先,本文将疏水管道划分成若干微元段控制体,建立圆筒壁传热模型。依据圆筒壁传热理论建立管道在不同阀门泄漏工况下的温度场计算模型。然后,以阀门未漏与阀门泄漏的两个诊断模型作为依据,建立了相对应的数学模型,并从中提炼出了管壁温度计算程序所需要的逻辑程序框图,在此基础上,编写了阀前管壁温度计算软件。与此同时,为了有效解决水蒸汽物性参数的计算精度,本文对水蒸汽状态方程和IAPWS-IF97的计算精度进行了分析,最终选择了IAPWS-IF97作为水蒸汽的物性参数的计算公式,在此基础上开发出了疏水管道管壁温度计算软件。最后,本文探索出一种火电厂蒸汽疏水阀门泄漏诊断新方法。该方法分两步对阀门进行泄漏故障进行诊断。第一步为定性诊断,通过疏水管道管壁温度计算软件计算出阀门未泄露时的管壁温度。管壁温度实测值低于此温度,判定阀门未发生泄漏。如果高于此温度,进行第二步定量诊断。通过对火电厂疏水管道在不同阀门泄漏工况下的温度场分布进行大量数值模拟计算,得出疏水管道壁温度与泄漏量、管道内径、保温层厚度等因素之间的变化关系,采用数学建模方法,把数值模拟所得出的数据拟合成定量计算公式,利用该计算公式实现阀门泄漏定量诊断。
[Abstract]:Valve leakage in thermal power plants will reduce the overall efficiency of the whole generator set, and may even directly threaten the safety of personnel and operation of the unit. At present, there are many methods to diagnose valve leakage, but these methods have some limitations. It is very difficult to diagnose the early leakage fault of valve in the complex environment of thermal power plant. Therefore, it is of great theoretical value and good engineering application prospect to study valve leakage fault based on the temperature field of drain pipe. The temperature of the front wall of the valve can be used as the diagnostic characteristic parameter to detect the leakage of the valve. The method of combining theoretical analysis, numerical simulation and engineering example is used in this paper. The leak detection method based on temperature field distribution of hydrophobic pipeline is studied and analyzed, and a new method for leak detection of drain valve door in thermal power plant is obtained. Firstly, the hydrophobic pipeline is divided into several microelement control bodies. The heat transfer model of cylinder wall is established. According to the theory of heat transfer of cylinder wall, the calculation model of temperature field of pipeline under different valve leakage conditions is established. Then, two diagnostic models of valve leakage and valve leakage are taken as the basis. The corresponding mathematical model is established, and the logical program block diagram of pipe wall temperature calculation program is abstracted from it. On the basis of this, the calculation software of pipe wall temperature in front of valve is compiled. At the same time, In order to effectively solve the calculation accuracy of the physical parameters of water vapor, the equation of state of water vapor and the calculation accuracy of IAPWS-IF97 are analyzed in this paper. Finally, IAPWS-IF97 is chosen as the calculation formula of the physical parameters of water vapor. On this basis, the software for calculating the wall temperature of the hydrophobic pipe is developed. Finally, In this paper, a new method of leak diagnosis of steam trap valve door in thermal power plant is explored. The method is divided into two steps to diagnose the leakage fault of valve. The first step is qualitative diagnosis. The wall temperature of the drain pipe is calculated by the software of pipe wall temperature calculation of the drain pipe. The measured value of the wall temperature of the pipe wall is lower than this temperature, and it is determined that there is no leakage of the valve. If the temperature is higher than this temperature, The second step of quantitative diagnosis. Through a large number of numerical simulation calculation of the temperature field distribution of the drain pipe in thermal power plant under different valve leakage conditions, the wall temperature and leakage volume of the drain pipe, the inner diameter of the pipeline are obtained. Based on the relationship between the thickness of insulation layer and other factors, the mathematical modeling method is used to simulate the data obtained by numerical simulation and the quantitative calculation formula is used to realize the quantitative diagnosis of valve leakage.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM621

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