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The Design And Optimization Of Diaphragm Type Chlorine Sensor Measurement System

Posted on:2019-11-07Degree:MasterType:Thesis
Country:ChinaCandidate:C ChenFull Text:PDF
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Disinfection of drinking water is the most important part of the process of drinking water purification and the most directly unit related to human health.The safety problem caused by drinking water disinfection has always been a hot topic in various countries.The use of chlorine disinfection has proven to be a clean,effective,and applicable drinking water disinfection method.After the introduction of chlorine production technology in the late 1980s in China,chlorine gas has been used for disinfection of drinking water.Disinfection of drinking water with chlorine generates total residual chlorine,including compounded residual chlorine(compounds of Chlorine and ammonia,including NH2CL,NHCL,,and NHCL,)and free residual chlorine(including OCL,CL2,HOCL in water).The residual chlorine in our definition of tap water refers to free residual chlorine,mainly including OCL-,CL2,HOCL in water.When the amount of residual chlorine in the water is too small,its continuous sterilization capacity cannot be guaranteed.while excess chlorine in the water can cause irritating effects on the skin and respiratory mucosa and make the body feel uncomfortable.Therefore,the value of residual chlorine has always been a very important indicator of water quality testing.Methods for determination of residual chlorine include silver chloride turbidimetry,spectrophotometry,iodine ion test strip titration,chromatography,and electrochemical measurement methods.The electrochemical measurement method has been discussed.We explained the working principle and design of the diaphragm type residual chlorine sensor measurement system in detail.In terms of the sensor,we introduced the structure of the sensor and the principle of the output signal.The optimization theory proposed the idea of changing the structure of the traditional auxiliary electrode to accelerate the reaction rate and designed the ion migration model of different types of auxiliary electrodes based on the knowledge of fluid mechanics.The signal processing circuit includes current-to-voltage circuit,differential amplifier circuit,secondary amplifier circuit,A/D converter circuit,single-chip processor circuit and LED display circuit.This article proposes the idea of modular circuit design,so that it is more convenient to test and replace the circuit.The addition of a denoising circuit makes the signal processing circuit less susceptible to external signal interference and enhances the stability of the signal processing circuit.The software part proposed the concept of segmentation calibration based on the traditional calibration curve.The experimentally measured data was divided into two groups:high-range and low-range.And the residual chlorine values in different ranges were applied with different calibration curves,making the residual chlorine measurement more accurate.When the repeatability of the residual chlorine sensor is well,the measurement system can realize the function of the look-up table.Followed by a series of experiments including the accuracy test and stability test of the residual chlorine measurement system,it shows that the optimized residual chlorine measurement system has good repeatability and accuracy and can be totally applied to the residual chlorine measurement of drinking water.
Keywords/Search Tags:diaphragm type, residual chlorine, electrochemical sensor, single-chip processor, optimization
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