超临界二氧化碳锅炉小径管焊瘤图像测量

Image measurement of weld beads on small diameter tube outside the supercritical carbon dioxide boiler

针对超临界二氧化碳发电站锅炉小径管焊瘤尺寸图像测量算法准确性低的问题,提出一种基于迭代最大熵阈值分割的焊瘤尺寸测量算法,涉及内管壁提取、内焊缝分割和焊瘤检测3部分。通过自适应阈值化和概率Hough算法检测管壁竖直线,对图像裁剪得到内管壁区域;采用UNet语义分割算法获取通孔区域分割掩模,根据通孔边缘和先验约束拟合出内焊缝壁椭圆;在内焊缝壁椭圆中,采用迭代最大熵阈值分割算法分割出焊瘤区域,并计算焊瘤尺寸。实验结果表明:焊瘤数目检测准确率达96.79%,焊瘤尺寸准确率达95.07%,能够对焊瘤特性进行精确测量。

Focusing on the low accuracy of weld size measurement algorithm in the radiographic image of small diameter tube placed outside the supercritical CO2 boiler,a size measurement algorithm based on maximum entropy threshold segmentation is proposed.The proposed method mainly includes three parts:inner wall extraction,welding area segmentation and weld detection.Firstly,the vertical line of pipe wall is detected by adaptive thresholding and probabilistic Hough transform(PHT),and then the image is cropped to get the inner weld wall region.UNet semantic segmentation algorithm is used to obtain the through-hole region segmentation mask,and the inner weld wall ellipse is fitted according to the through-hole edge and prior constraints.Furthermore,the weld area is precisely segmented by the maximum entropy threshold to calculate the weld size in the weld detection module.The experimental results show that,the accuracy of welding beads’number reaches 96.79%,and the accuracy of welding beads’dimensions reaches 95.07%,indicating the size of weld beads can be measured accurately.