【作者】 郭亮；

【导师】 孙荣霞；

【作者基本信息】 河北大学 ， 检测技术与自动化装置， 2010， 硕士

【摘要】 臭氧作为一种高效且无二次污染的强氧化剂,它在医疗卫生、污水治理、家居消毒等方面被广泛应用。但是在农业生产领域中,臭氧技术应用在大棚温室病虫害防治上属于刚刚起步阶段。臭氧不仅可以杀灭各种病虫害,而且还可清洁表层土壤和植物表面的毒素,消除药物残留,为温室作物创造良好的生态环境。但目前的臭氧设备自动化水平低、功能单一,不能实时准确检测控制臭氧浓度,同时,臭氧浓度过高会对大棚农作物、操作人员造成损害。针对这些问题,本文研究和设计一种能实时在线检测臭氧浓度的测控系统,同时能够检测气体流量和温度,实现整个臭氧生产过程的闭环控制。本文首先介绍了介质阻挡放电产生臭氧的方法,给出了介质阻挡放电电路的放电功率,为构成闭环控制系统提供了理论依据,又着重介绍了紫外辐射吸收法的工作原理,并采用该方法进行臭氧浓度的检测;其次重点介绍了臭氧发生器的供电电源,选用串联谐振式IGBT逆变电源作为供电电源,设计了一种基于CD4046的频率跟踪移相PWM控制电路,通过改变电源电压的大小,调节臭氧放电功率,实现臭氧浓度的调节;为实时检测臭氧浓度,设计了基于ADμC812单片机为核心的微机控制系统,完成了对光强、温度、流量和峰值电压信号的采集及存储,并与PC机进行通讯;下位机软件采用C语言编写,上位机软件采用VC++编写,实现人机对话控制功能;最后在改进后的50g/h的臭氧发生装置上进行系统试验测试。在稳定状态下,进行系统试验测试得出:当气体流量为100ml/min,电压峰值为5000V,系统温度稳定在26.5℃左右时,臭氧浓度趋于稳定在40.35mg/L,完成了臭氧浓度测控系统的在线检测功能;再将测试结果与传统的碘化钾滴定法测试结果进行比较,系统测试值的相对误差不超出3%,系统检测精度为0.01mg/L,满足大棚温室使用要求,具有一定的实用性;在温度、流量、峰值电压这三个系统参数值分别发生变化时,进行系统试验测试,测试结果验证了这三个系统参数对臭氧浓度影响的理论正确性,实现了对温度、流量及峰值电压的在线控制。更多还原

【Abstract】 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.更多还原