锁相技术在FSM管道腐蚀测量中的应用

基于电位阵列的金属管道(容器)在线腐蚀检测方法称为场指纹法(field signature method,FSM).FSM是一种新型的石油、天然气管道腐蚀监测技术.它通过检测管道外部两两电极间电位差的变化,来判断管道的腐蚀情况.由于电极间的电位差极其微弱(30～60 μV),因此微弱信号的测量精度决定了腐蚀检测的精度.锁相放大技术是一种提取淹没在噪声中微弱信号的重要手段,广泛用于微弱信号检测系统中.介绍锁相放大技术的微弱信号检测电路的设计以及在FSM管道腐蚀测量系统的应用,同时针对测量信号是低频的特点,在系统中采用数字与模拟相结合的方法,大幅度提高了其测量精度以及稳定性,达到了项目的要求.

Applications of lock-in amplifying in the FSM pipe corrosion monitoring

Online metal pipe corrosion monitoring method on potential-array is also known as field signature method （FSM）. FSM is a new method which is used to monitor pipe corrosion of petroleum and natural gas. The degree of corrosion is calculated by detecting the change of electric potential difference between the electrodes on tube exterior. The signal is extreme weak, so the accuracy of weak signal detection impact on the accuracy of corrosion detection, lockin amplifying （LIA） is one of important techniques for weak signal detection, and it is widely used in the system of weak signal detection. This paper describes a designing of a weak signal detection circuit based on Lock-in amplifying, and the application in the pipe corrosion detection system. Aiming at the characteristics of low frequency,a method is used in this system to improve the accuracy and stability of measurement, which combines digital with analogy. This system achieves the requirement of project.