一种电阻法检测持水率方法

摘要

针对电阻法检测持水率存在的问题,研究了探针式电阻传感器的等效模型.在分析国内外现有电阻式持水率检测仪器方案的基础上,提出了一种适用于油水两相分离状态的持水率检测方法.考虑到分布电容对测量结果的影响,采用了双极性脉冲激励方法,设计实现了同时检测电压和电流的检测方案,开发了基于延时同步采样保持的检测电路.试验结果表明,该方法能准确识别油和水,消除分布电容对测量结果的影响,减小杂散电阻(即探针正参考电极与仪器外壳间的电阻)引起的测量误差,提高电阻测量的精度.该方法实现了通过实测电阻值反映持水率信息,对阵列电阻式持水率检测仪器研究具有参考价值.%In accordance with the problem existing in resistance detection method for water holding capacity,the equivalent model of the probe-type resistance sensor is studied.On the basis of analyzing the detection strategies of domestic and foreign resistance instruments for water holding capacity,the detection method suitable for oil-water two-phase separated state is proposed.Taking into account of the influence of distributed capacitance on the measurement results,by using bipolar-pulse excitation method,the detection scheme for detecting both voltage and current is designed and realized,and the detection circuit based on time delayed synchronous sampling and hold is developed.The result of tests shows that this method can accurately identify oil and water,eliminate the influence of distributed capacitance on the measurement result and reduce the measurement error caused by the stray resistance (i.e.,the resistance between the positive reference electrode of the probe and the housing of instrument),thus the accuracy of measurement of resistance is improved.In the true sense,this method get the information reflects the water holding capacity through the resistance value measured.