On Line Detection Device For Plate Defect Of Plate Heat Exchanger

Plate heat exchanger is a kind of heat and cold exchanger commonly used in daily life and industrial production.It is widely used in metallurgy,mining,petroleum,chemical industry,electric power,medicine,food,chemical fiber,papermaking,light textile,ship,heating and other departments.The plate of plate heat exchanger is the core component of plate heat exchanger.The defective plate not only affects the heat exchange efficiency of the heat exchanger,but also reduces its service life,which will cause safety hazards to the heat exchanger.At present,the inspection of plate heat exchanger is mainly based on manual sampling,which is hard to meet the requirements of quality inspection due to its heavy workload,low efficiency and high rate of false inspection.To some extent,the safety factor of plate heat exchanger is reduced.Therefore,it has a certain practical significance for the automatic detection of plate defects in plate heat exchanger.In view of the deficiency of manual detection of plate ripple depth defect,this paper designs an on-line detection system for plate ripple depth defect of plate heat exchanger,which uses laser triangulation method to realize the detection of plate ripple depth of plate heat exchanger.According to different types of plates,the mechanical platform of the detection system is designed to solve the problem that the plates can move smoothly from the loading station to the depth detection station.According to the characteristics of plate structure,the depth data acquisition path is designed,and the data acquisition of different plate depth is completed.PC and PLC realize real-time information exchange through OPC communication and RS422 communication with laser displacement sensor.In the data processing part,the source of abnormal data is analyzed,and the problem of noise reduction is solved by using adaptive iterative median filtering algorithm.The data after noise reduction is transformed into visual image area and gray image to extract gasket groove area intuitively and efficiently.The least square method is used to fit the gasket groove area of corrugated plate,and the parameters of corrugated depth are calculated by using moments in statistics to judge plate quality of plate heat exchanger.The detection time of the single board algorithm designed in this paper is up to 41.0259s.and the detection results of narrow corrugated board are different from that of manual detection.The main reason is that the laser displacement sensor moves too fast to collect,which leads to the loss of a lot of effective data of narrow corrugated board.The test results of wide corrugated plates can basically meet the needs of the site.There are three main reasons for the difference between some detection results and manual detection:first,there are differences between the actual location of the machine and the manual detection;second,manual detection can correct the slight deformation of the plate by applying pressure through the arm;third,the artificial detection value is affected by its own objective factors.