基于虚拟仪器的油品含水量快速检测系统.doc

摘要
油品含水量是石油化工等行业一个重要的参数,油品含水直接影响油品的生产、运输、储存和使用。有些油品只允许微量水分存在,有些油品却不允许水分存在。因此对油品进行含水量的精确测量具有重要的意义。
本文介绍了基于虚拟仪器的油品含水量快速检测系统的设计过程,、数据处理、数据显示与存储。利用水的介电常数远大于油的介电常数,两者所呈现的射频阻抗不同的特点,采用射频电容法检测油品中的水分含量。针对检测过程中环境温度会影响传感器的输出值和测量精度的问题,通过同时对水分和温度两个参量进行检测,然后利用曲面拟合算法进行温度补偿处理,以提高系统测量精度。
该检测系统对油品含水量的检测设计了两种方案。第一种方案选择射频电容传感器采集水分电压信号和温度电压信号,通过信号调理电路对信号进行放大滤波后,由PCI-6024E数据采集卡读取数据,进行A∕D转换,最后送到计算机,;第二种方案是该系统作为上位机,接收下位机(单片机系统)采集的水分和温度电压信号,,实现数据处理、显示与存储。
采用本系统对重油含水量进行检测和实验数据分析,结果表明,本系统操作简单、稳定性好、测量精度高。
关键词:油品含水量虚拟仪器介电常数射频电容法曲面拟合算法
ABSTRACT
The moisture in oil, which directly affects the oil production, transportation, storage and use, is one of the important parameters in petrochemical industries. Some oil is allowed to have little water, but any is not allowed. Therefore, the accurate measurement of moisture in oil is of great significance.
In this paper, the designed process of the system for rapid detection of moisture in oil based virtual instrument is introduced and the virtual instrument development platform is used to design the program of data acquisition, data processing, data display and storage. The dielectric constant of water is much larger than that of oil and the radiofrequency resistance showed by water and oil is fairly different. Radiofrequency capacitive method is used to measure the moisture in oil. However, it is found in the measure process that the output values and measurement accuracy of the sensor are affected by ambient temperature. The water and the temperature are detected by the radiofrequency capacitive sensor at the same time, and the surface-fitting algorithm for pensation is used to improve the measurement accuracy in the system.
Two measurement schemes are designed in the system. One is that radiofrequency capacitive sensor is used to acquire voltage signal of the water and the temperature and signal conditioning circuits are used to ampl