基于TDC-GP21芯片的超声波管道腐蚀监测技术

Ultrasonic Pipeline Corrosion Monitoring Technology Based on TDC-GP21 Chip

针对在役化工金属管道因腐蚀而产生管壁减薄的现象,研究了超声波腐蚀检测技术,实现管道腐蚀的定点周期性监测。基于超声波脉冲反射法测厚原理,提出了超声波管道腐蚀监测系统具体的设计方案。采用高速电压比较器结合时间数字转换芯片TDC-GP21构成数据处理单元,实现管道壁厚的高精度测量。采用滞回式电压比较电路,输出信号的上升沿陡峭、噪声小;时间测量电路输出的时间测量值由LCD液晶屏显示,分辨率为0.000 1μs;计算分析得出,管道厚度测量平均误差小于1%;系统多次测量的重复性较好。

In term of the thinning phenomenon of in-service chemical metal pipelines wall due to corrosion, to realize the fixed- point periodic monitoring of pipeline corrosion, the system of ultrasonic corrosion monitoring was studied. Based on the principle of ultrasonic thickness measurement, the concrete design plan was proposed. To realize high-precision measurement of pipe wall thick- ness, high-speed voltage comparator combined with time-digital converter chip TDC-GP21 was used to constitute data processing u- nit. The hysteresis-type voltage comparator circuit was used, so the rising edge of the output signal was abrupt and of low noise ; t output by time measuring circuit was displayed by LCD and the resolution ratio was 0. 000 1 μs. Calculation and analysis prove that the average measurement error of the thickness is less than 1% and the system＇s repeatability of repeated meas- uring is excellent.