Research On Automatic Cleaning And Calibration Device Of Online Water Quality Detection Sensor

Online water quality detection technology is an important means of water environment protection.There are some shortcomings of current online water quality detection system: such as the system requires long-term online operation,thus the surface of the sensor used for water quality detection is easily contaminated by dirt particles,microorganisms,and the magnesium ion precipitation or scaling.The pollution problem will lead to the inaccuracy of sensor output signal,sensor's zero drift and linear slope drift.At present,it needs to carry out regular manual cleaning,calibration and other maintenance.Because the water quality detection points are scattered in a big area,it brings a lot of manpower and financial consumption.Therefore,this paper designs an automatic cleaning and calibration device for the online water quality detection sensor.In this device the sensor is regularly cleaned and calibrated.We hope to solve the problem of contamination of the online water quality detection sensor and improve the reliability and extend the service life of sensors.To achieve these goals,firstly,the causes of the sensor surface contamination,factors and the surface fouling mechanisms are analyzed.The commonly used sensor cleaning methods and their effectiveness are reviewed and discussed.Secondly,the automatic cleaning and calibration device is designed and studied with the aid of theoretical analysis and simulation.These works include the analysis and studying the working parameters of high-pressure water jet technology for the cleaning of the contaminated sensors and the mechanism,the design of the prototype device for automatic cleaning and calibration of online water quality detection sensors,and the optimization of the working parameters of the software and hardware of the device.Then,the segmented data interpolation method and the segmented least squares method are used to calibrate the detection data corresponding to the electrical signal of the contaminated PH sensor.Technologies,such as nonlinear calibration and parameter compensation are used to improve the accuracy of the sensor for a long time running.Finally,based on the above theoretical analysis and simulation results,the sensor cleaning and calibration prototype device is designed,built and used to clean,calibrate and evaluated the cleaning effect of the contaminated sensors to achieve the expected goals.In this paper,an automatic cleaning and calibration device of online water quality detection sensors is designed and built.And various calibration methods for electrode type sensors are analyzed.The automatic cleaning and calibration work are completed by using touch screen display control technology.Results show that it can clean and calibrate contaminated sensors effectively,improve the accuracy and continuity of water sample detection in online water quality detection system and reduce the cost of manpower and system operation.