The Study And Design Of An Examining Free Chlorine System Based On Three-Electrode

Nowadays, chlorination is widely used in the disinfection process in water treatment in our country. More and more attention has been paid to the measurement of free chlorine in domestic water while residual chlorine is one of the most important parameters to appraise the water quality. Measurement of free chlorine is of great significance for ensuring water safety.The research background and development status at home and abroad of free chlorine measurement have been introduced in the paper, and the study of examining free chlorine is based on a combination of chemical sensor technology and embedded technology. We had independently designed and developed a high-performance measurement system of free chlorine, and focused on the design process of hardware and software. In the first place, we introduce the structure and principle of free chlorine detection, while elaborating Fick’s first law, Faraday’s laws of electrolysis and Arrhenius equation. Secondly, the hardware design of measurement system is given in detail, including the development of sensor and the design of signal conditioning circuit. On the basis of analyzing the material of the electrodes, we studied the fabrication process of the sensor and the PCB design of free chlorine measurement system. Then through designing the system architecture of free chlorine measurement and analyzing the file system structure of RT-Thread embedded real time operation system, we summarized the major steps of transplantation of RT-Thread and design the program of free chlorine, temperature and pH measurement according to the principles of real-time operating system, and calibration program is designed to extend the service life of the sensor. Finally, we introduce the calibration experiments of the free chlorine measurement system, while analyzing the results of calibration, the stability and accuracy of the system have been tested.Experimental test results indicate that the measurement system using residual chlorine sensor with three electrodes has stable performance, which can be used for the detection of free chlorine in drinking water, boiler feed water and sewage treatment.