The Research And Design Of The Ozone Concentration Measurement And Control System

Ozone as a strong oxidizer which is efficient and have no secondary pollution, it is widely used in the fields of health care, water treatment and household disinfectant. But in the field of agricultural production, the ozone technology is just beginning, such as disease and pest control in greenhouse. Ozone could not only kill a variety of plant diseases and insect pests, but also clean the toxins of the topsoil and plant surface, eliminate drug residues, which creates a good ecological environment for greenhouse crops. At present, Ozone equipments are at the low automation, single function, which could not accurately detect real-time control of ozone concentration, meanwhile, high ozone concentrations will cause damage to the greenhouse crops and operators. In order to solve these problems, an ozone concentration measurement and control system is researched and designed which could detect the ozone concentration in real-time online. It is also able to detect the gas flow, temperature and achieve closed-loop control of the ozone production process.First, this paper introduces the method of dielectric barrier discharge produce ozone, gives the discharge power of dielectric barrier discharge circuit, which provided a theoretical basis for the closed loop control system; Second, it emphatically introduces the power supply of ozone generator, which used serial-resonant IGBT inverter as a power supply, designed a type of frequency tracking phase shift PWM control circuit based on CD4046, by changing the size of the supply voltage to regulate the ozone discharge power, to achieve the regulation of ozone; In order to Real-time detection of ozone concentration, it designed the microcomputer control system based on AduC812 MCU, completed the light intensity, temperature, flow rate and peak voltage signal acquisition and storage, and communicated with the PC machine; The lower computer software uses C language, PC software was written by VC++, which realized man-machine dialogue control; Finally, it had system test under improved 50g/h of ozone testing device.In the steady state, system testing obtained: When gas flow is 100ml/min, peak voltage is 5000V, system temperature is stabilized at about 26.50C, the ozone concentration tends to stabilize at 40.35mg/L, Ozone concentration control system completes the online detection; Then compared the test results to the traditional potassium iodide titration method, the relative error of test value does not exceed 3%,the detection accuracy is 0.01mg/L, which is meet the application requirements of greenhouses. It has some practicability; When the temperature, flow rate and peak voltage value of the three system parameters changes, the test results show the theoretical correctness of three system parameters impact on the ozone concentration. It achieves the online control of the temperature, flow and peak voltage.