便携式农残检测气相色谱仪温度控制系统的研究

发布时间：2018-05-28 17:14

  本文选题：便携式 + 气相色谱　； 参考：《合肥工业大学》2016年硕士论文

【摘要】：气相色谱技术在分析化学领域内占据着重要的地位。因其具有对复杂混合物进行分离和检测的能力,使之在石油、化工、农业等行业都有着广泛地应用。近年来,农药残留检测等现场检测工作日益增多,而传统的气相色谱仪由于结构复杂,体积较大难以满足现场检测的要求。因此,便携式、微型化已经成为气相色谱技术发展的一个重要趋势。而温度控制系统是整个气相色谱控制系统的核心,因此,温度控制系统的微型化研究是便携式气相色谱仪研究开发的重点之一针对这一问题,本文设计了两种微型化的色谱柱加热方式：一种是使用3D打印技术制作的小型色谱箱对色谱柱加热的方式,另一种是通过不锈钢毛细管直接对色谱柱加热的方式。本文针对第一种加热结构设计了一种基于Micro2440控制板和Linux系统的嵌入式微型化温控系统。这种控温结构既精简了温控电路又缩小了温控系统硬件所占的空间。该控温系统的主要硬件为Micro2440主控制板,以及集成在其内部的三路ADC转化器与三路GPIO输出接口。三路ADC与GPIO分别应用于进样器、毛细管柱加热箱以及检测器的温控。温控的主要过程为主线程通过ADC从温度采集模块得到当前温度,然后根据该温度值经过PID算法计算出本次加热时间并通过设置GPIO来执行加热。本文所采用PID控制算法是单神经元加PID的算法,并采用有监督的赫布规则来动态修正PID算法中的比例、积分及微分系数。最后,通过升温实验结果表明,本文设计的气相色谱温控系统控温精度能达到±0.5℃,并实现了程序升温功能。而搭载这种温控系统的便携式气相色谱仪,在实验室环境下成功地检测出了敌敌畏、敌百虫等有机磷混合物。
[Abstract]:Gas chromatography plays an important role in analytical chemistry. Because of its ability to separate and detect complex mixtures, it is widely used in petroleum, chemical, agricultural and other industries. In recent years, the field detection work such as pesticide residue detection is increasing day by day, but the traditional gas chromatograph is difficult to meet the requirements of field detection because of its complex structure and large volume. Therefore, portable and miniaturization has become an important trend in the development of gas chromatography technology. The temperature control system is the core of the whole gas chromatography control system. Therefore, the miniaturization of the temperature control system is one of the key points in the research and development of portable gas chromatograph. In this paper, two kinds of micro-column heating methods are designed: one is a small chromatographic box made by 3D printing technology to heat the column, the other is the direct heating of the chromatographic column through stainless steel capillary. In this paper, an embedded miniaturized temperature control system based on Micro2440 control board and Linux system is designed for the first heating structure. The temperature control structure not only simplifies the temperature control circuit but also reduces the space occupied by the hardware of the temperature control system. The main hardware of the temperature control system is the Micro2440 main control board, as well as the three-way ADC converter integrated in its interior and the three-way GPIO output interface. Three-channel ADC and GPIO are used in temperature control of sampler, capillary column heating box and detector, respectively. The main process of temperature control is to get the current temperature from the temperature acquisition module by ADC. Then the heating time is calculated by PID algorithm according to the temperature value and the heating time is executed by setting GPIO. The PID control algorithm used in this paper is a single neuron plus PID algorithm, and the supervised Herb rule is used to dynamically modify the proportion, integral and differential coefficients of the PID algorithm. Finally, the experimental results show that the temperature control system designed in this paper can achieve 卤0.5 鈩，

本文编号：1947528