天然气管道球阀内漏发声机理及检测试验
Acoustic Emission Mechanism and Testing of Leakage in Natural Gas Pipeline Ball Valve

球阀作为高压天然气输送管道的主要设备，其内漏时的喷流气体会产生声发射信号，通过研究该声发射信号特征规律将有助于阀门内漏流量量化检测。针对这一问题，进行了天然气输送管道球阀内漏发声机理和检测试验研究，分析了阀门内漏声发射现象产生的机理和内漏流量检测评价方法。在此基础上，应用声发射检测系统对3种不同尺寸内漏球阀进行了检测试验，通过试验分析了球阀在不同内漏流量下的声发射信号频谱特征分布规律，并采用小波包分析方法进行信号特征参数（信息熵、均方根、频域峰值）提取。拟合特征参数与内漏流量关系曲线，采用R2（确定系数）指标对曲线拟合程度进行评价，评价结果表明，采用均方根值（root mean square,简称RMS）的曲线拟合程度最高（R2为0.979），可以用于天然气输送管道球阀内漏流量的量化检测。
The jet gas from the internal leakage in a ball valve, which is an indispensable equipment in a high-pressure natural gas transmission pipeline, can produce acoustic emission (AE) signals. Thus, the research on the characteristic rule of the AE signals will be helpful for the quantitative detection of the valve leakage flow. In dealing with this problem, the AE mechanism and testing of internal leakage in a ball valve are investigated. An AE testing system is used to measure the leakage in ball valves of three different sizes. In the analysis process of the testing data, the spectrum distribution characteristics of the AE signals on leakage levels are described, and the characteristic parameters of signals (information entropy, root mean square (RMS) and frequency peak) are extracted using the wavelet packet analysis method. On this basis, fitted curves about the characteristic parameters and the leakage flow are established, and the correlation is evaluated using the R-square (determination coefficient). The evaluation results show that the RMS value with the highest correlation (R-square =0.979) can be used for the quantitative detection of leakage in a ball valve in the natural gas pipeline.