危险化学品输送管道泄漏检测系统设计

发布时间：2019-03-20 18:13

【摘要】：危险化学品输送管道的泄漏检测是保证安全生产的重要环节。由于危险化学品的强腐蚀、易燃、易爆、有毒、放射性等危险特性,危险化学品输送管道泄漏检测系统要具有响应时间快、灵敏度高、定位精确等功能,同时也要求使用和维护操作简便,而当前基于声波法的危险化学品输送管道泄漏检测系统应用很少。因此,危险化学品输送管道泄漏检测系统的设计与应用是保障危险化学品领域安全生产的必要前提。本课题以危险化学品输送管道为研究对象,通过设计增益可远程调节的管道泄漏检测现场仪表提高系统的可操作性,提出基于双移动窗和功率谱比对的信号特征提取方法提高特征提取的有效性,建立了基于SVDD的无泄漏样本信号条件下危险化学品输送管道泄漏诊断模型,解决危险化学品输送管道不能获取真实“模拟泄漏信号”的难题,从而为减少误报,消除漏报提供了必要的技术手段。由于同一型号传感器在不同的管道输送介质中的输出信号特性相似。本课题从同一型号传感器在天然气输送管道上的信号入手,分析、比较了正常动态压力信号和泄漏动态压力信号的功率谱的异同,提出了基于双移动窗和功率谱比对的信号特征提取方法和步骤。然后,将该特征提取方法应用在危险化学品输送管道动态压力信号的特征提取中。然后,建立了基于SVDD的无泄漏样本信号条件下的泄漏诊断模型。在危险化学品输送管道的泄漏检测系统设计中,一方面设计了基于STM32微处理器的现场仪表,现场仪表能接收嵌入式远程终端单元(RTU)的信号逐级放大调节指令,将压电式压力传感器的输出信号按指令要求的放大倍数放大,最后输出4-20mA标准信号；另一方面改进了集成RS-485串行通信总线功能的嵌入式远程终端单元(RTU),RTU不仅能够采集现场仪表的输出信号,以网络通信方式传输至监控服务器,而且能够接收监控服务器发送的仪表放大倍数调节指令,将调节指令经RS-485串行通信总线转发至现场仪表。最后,在液氯输送管道中以液氮为实验介质,通过模拟泄漏对该系统进行了检验,系统全部做出了正确报警。连续运行结果表明：本文设计的危险化学品输送管道泄漏检测系统误报率低,并且能够有效诊断管道的泄漏。
[Abstract]:Leakage detection of dangerous chemical pipeline is an important link to ensure safe production. Due to the dangerous characteristics of dangerous chemicals such as strong corrosion, flammability, explosion, toxicity and radioactivity, the leak detection system of dangerous chemicals transportation pipeline should have the functions of quick response time, high sensitivity, accurate positioning, and so on. At the same time, it is also required to use and maintain easily, but the application of leak detection system based on acoustic method for dangerous chemical pipeline is very few. Therefore, the design and application of leakage detection system for dangerous chemical pipeline is a necessary prerequisite to ensure the safety of production in the field of hazardous chemicals. In this paper, the pipeline of dangerous chemical transportation is taken as the research object, and the operability of the system is improved by designing the field instrument of pipeline leakage detection, which can adjust the gain remotely. A signal feature extraction method based on double moving windows and power spectrum comparison is proposed to improve the effectiveness of feature extraction. A leakage diagnosis model of hazardous chemical pipeline without leakage sample signal based on SVDD is established. In order to solve the problem that the pipeline of dangerous chemicals can not obtain the real "simulated leakage signal", it provides the necessary technical means for reducing false alarm and eliminating underreporting. Because of the same type of sensors in different pipeline transport medium, the output signal characteristics are similar. Starting with the signal of the same type of sensor in the natural gas pipeline, this paper analyzes and compares the power spectrum of the normal dynamic pressure signal and the leakage dynamic pressure signal. The method and steps of signal feature extraction based on double moving window and power spectrum comparison are proposed. Then, this feature extraction method is applied to feature extraction of dynamic pressure signal in dangerous chemical pipeline. Then, a leak diagnosis model based on SVDD is established under the condition of no leakage sample signal. In the design of leakage detection system for dangerous chemical pipeline, on the one hand, the field instrument based on STM32 microprocessor is designed. The field instrument can receive the signal of embedded remote terminal unit (RTU) to amplify and adjust the instruction step by step. The output signal of the piezoelectric pressure sensor is amplified according to the magnification required by the instruction, and finally the 4-20mA standard signal is outputted. On the other hand, the embedded remote terminal unit (RTU), RTU, which integrates the function of RS-485 serial communication bus, can not only collect the output signal of the field instrument, but also transmit it to the monitoring server by means of network communication. At the same time, it can receive the instrument magnification adjustment instructions sent by the monitor server and forward the adjustment instructions to the field instrument via RS-485 serial communication bus. Finally, using liquid nitrogen as the experimental medium in the liquid chlorine pipeline, the system was tested by simulated leakage, and all the system made the correct alarm. The continuous operation results show that the leakage detection system designed in this paper has low false alarm rate and can effectively diagnose pipeline leakage.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U178

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