Infrared Three-dimensional Diagnosis Technology For The Defects Of High Temperature Containers

As many industrial containers operating continuously under the bad environment of high temperatures,high pressure and chemical corrosion for a long time,the inner wall of equipments easily generates stress and corrosion,leading to defects or damages in the interior of equipments,which bring great dangers to the safety of production.So the efficient on-line inspection of industrial containers is very important.Infrared thermal image detection technology is a new nondestructive testing method.Through analyzing the infrared image,the situation of internal defects in the containers can be evaluated.It is suitable to detect the equipments which are working,and has been widely used in many fields,such as electricity,metallurgy,petrochemistry and so on.But the technology also exists in some shortcomings,such as judging the geometric features and locations of defects inaccurately based on infrared image,which result in the insufficient of diagnostic accuracy and practicability.To solve this problem,infrared three-dimensional diagnosis technology is researched to diagnose the defects of high temperature containers.Using 3d laser scanner to obtain three-dimensional point cloud data of container,container precise geometry field is established and at the same time the temperature field of container is contained by thermal infrared camera.The three-dimensional multi-source field is formed through the superposition of the temperature field and accurate 3d geometry field,and then the precise three-dimensional diagnosis of defects can be realized on the 3d multi-source field by combining with numerical simulation technology.The main contents of this paper are as follows:Firstly,the reliability of diagnosis of container defects by using infrared three-dimensional diagnosis technology is verified through the experiment and the advantages of the technology are studied.The results show that 3d visualization of defect diagnosis can be realized on the point cloud,also the accurate positioning and size measurement of defects.The laws on the impact of temperature difference to detection effect,detection distance to detection effect and defect parameters to defect detection are studies and the results are as show:(1)increasing the temperature difference value can improve the detection capability of the technology;(2)reducing the detection distance can improve the detection effect of the technology;(3)the greater the size and depth of the defect,the greater the maximum detectable distance;(4)the greater the size and depth of the defect,the easier it is to be detected.When using the infrared three-dimensional diagnostic technology to diagnose containers,it is not enough to determine whether the defects exist and it is often necessary to analyze the internal defects of the containers based on the obtained container surface temperature images.For this problem,blast furnace hearth is taken as the research object,the furmace wall 3d models with different defects are built and the surface temperature images of furnace wall are acquired by using the ANSYS finite element software for the simulation.The characteristics of the surface temperature images of the furnace wall corresponding to different defects are analyzed and summarized,so as to provide the necessary basis for the analysis of internal defects in practical engineering.Finally,the containers in the factory are diagnosed by using the infrared three-dimensional diagnostic technology.The digital imaging models of containers are built by using the acquired data.The defects are diagnosed and the defect information including sizes,coordinates and distances from the ground are also measured on the point cloud.At the same time,it is compared with the temperature images obtained in the previous numerical simulation to infer the possible situation of the internal defects of the containers,so as to provide accurate basis for guiding the equipment maintenance.