基于CAV444的电容式原油含水率在线检测

针对传统电容式传感器测量原油含水率的结构复杂,测量过程易受寄生电容和外界环境温度影响,设计了一种基于新型电容/电压转换芯片CAV444的原油含水率检测系统。原油含水率变化经电容传感器检测后表现为电容值的变化,再通过CAV444转换得到差分电压输出。实验表明:本设计稳定可靠,能满足工业现场需求,在现代化油田监测中具有应用价值。     

基于嵌入式油品含水率检测系统的设计

文中设计了一种基于嵌入式的油品含水率检测系统。该系统硬件部分设计了电容-电压转换电路、温度测量电路、串口通信电路以及单片机最小系统电路等。通过设计的电容传感器来检测油中的含水量,把含水量的多少转换为电容传感器电容值的变化,最后根据相应关系计算出含水率。经实验研究表明,该系统含水率检测精度达到了0.01级,测量精度高、稳定性好。     

基于CAV424的油品含水率在线测量仪的研制

提出了一种电容传感器调理电路的新方法,引入了用于电容／电压信号转换的集成电路CAV424,以及CAV424在油品含水率测量仪中的应用。     

基于ARM的高精度动力油品含水率检测系统

动力油品含水率影响各类设备中液压系统、燃油系统、滑油系统的可靠性和安全性,高端设备要求含水率指标为0.01级。文中采用S3C2410 ARM9作为控制核心,以Win CE作为操作系统,设计了电容传感器检测含有水分的油品,实现含水率与电容值变化的转换,并通过AD7745将电容量数字化获得含水率数据。经过对润滑油和轻质成品油的检测实验,结果表明:在-5~+60℃温度条件下和0%~0.35%含水率范围内,含水率检测精度达到了0.01,且具有重复性好、可靠性高等优点。可应用在各类对油品含水率要求严格的工业、商业等领域,以保证动力系统的可靠性和安全性。     

基于电容电导法的原油含水率测试仪设计

提出了新的基于电容电导法的原油含水率测量方案.制作了平行板式传感器,设计了电容、电导测量电路,以数字信号处理器TMS320LF2407为核心设计了原油含水率测试仪样机.在含水率测试仪的数据处理中,采用了基于BP人工神经网络的多传感器信息融合技术.实验室进行的初步实验表明此方案能够实现全量程含水率的测量,具有较高的精度.     

基于TDC的一种微小电容高精度测量系统设计

针对电容原理传感器中对微小电容的测量要求,利用PcapΦ2芯片具有的高精度计时能力,设计了一个基于时间-数字转换的微小电容高精度测量系统。详细阐述了整个测量系统的实现原理和软硬件设计方法,给出了内部和外部寄生电容的补偿方法,并提出了一个适用于大多电容传感器设计的一个外围电路较为简单的高集成度单芯片解决方案。     

基于厚膜电容传感的微位移信号处理电路设计

设计了一种基于电容数字转换芯片AD7745和单片机C8051F040微位移检测信号处理电路,给出了电容式微位移传感器的设计制备原理、C8051F040软硬件设计、输出转换电路的设计, 阐述了微位移检测电路信号提取及转换过程.实验结果表明:设计的微位移信号处理电路提高了厚膜微位移电容传感器的稳定性及抗干扰能力,并使传感器在量程100 μm的范围内线性度由6.10%提高到0.67%.     

油水两相流中2种含水率计算模型比较

油水两相流广泛存在于石油开采、储运、化工、能源等工业领域。含水率是油水两相流系统的重要参数之一,含水率的准确测量不仅与采用的测量方法有关,而且还与计算模型有很大关系。结合电导式测量方法建立了电阻-电容并联网络含水率计算模型,并在3种流型下与Maxwell含水率模型进行了仿真和实验对比。结果表明,建立的并联电阻-电容网络含水率模型,在泡状流下与Maxwell含水率计算模型的误差基本相同,而在环状流、分层流下,测试误差均小于Maxwell含水率计算模型的误差,具有更高的测试精度,可适用于环状流、分层流、泡状流等流型。     

原油含水率检测电路的设计

在介绍CAV424测量原理和变介电常数型电容传感器工作原理的基础上,设计了一种基于CAV424的电容传感器原油含水率检测电路.测量时,CAV424将电容变化量转换成差动电压信号,送给差动放大器INA101放大后形成与含水率对应的输出电压.通过试验表明:检测电路测量原油含水率与蒸馏水法测量值的差值在5%以内,较好地克服了电容法测量时调理电路易受寄生电容和环境变化影响的问题,具有测量准确度高,测量速度快,显示直观,安装使用简单,价格低廉,操作方便的特点.     

提高电容层析成像系统实时性研究

为适应工业过程参数检测,特别是高速流体检测的需求,提出了数字相敏解调与持零开关策略相结合的方法以改善电容层析成像系统的实时性。交流C/V转换电路具有信噪比高、动态测量范围大的特点,被广泛应用于电容层析成像系统。目前,该种电容层析成像系统可达到250幅/秒的采集速度,但依然无法满足高速流体检测的要求。为此,分析了影响ECT系统实时性的各种因素,并着重介绍了利用数字相敏解调与持零开关策略提高实时性的方法。实验结果表明,采用该方法后12电极电容层析成像系统的数据采集速度可提高至1 000幅/秒,同时保持较高的信噪比。     

润滑油含水率检测电容传感器的设计及实验研究

利用油与水介电常数差别较大的特性,借助电容式传感器可测出油品含水率。设计平行板式、圆柱形、圆筒形和螺旋线式4种电容传感器,对润滑油含水率进行检测。对4种传感器检测结果进行比较,分析测量值与理论值之间的差异,阐述影响电容传感器检测精度的因素,比较4种类型传感器的分辨率。结果表明:平行板式与圆柱式电容传感器对水的分辨率相对其他2种传感器效果要好,且在高含水率时,平行板传感器效果更加明显。     

A theoretical model for a capacitance tool and its application to production logging

A new theoretical model for a capacitance sensor used for measuring water holdup in production logging is proposed in this paper. The model realizes that the capacitance sensor is sensitive to oil droplets that collide against the sensor's inner electrode coated with an insulator when the water is electrically conductive and is the continuous phase in an oil/water bubbly flow. The sensor still has the ability to distinguish between oil and water in this case, its sensitivity decreasing with fluid velocity. The experiments were performed in a multiphase flow loop, and the results strongly confirm the theory. On the basis of the model, the measuring principle of the sampling-type capacitance tool is discussed, and an attempt to evaluate average oil droplet size with the capacitance sensor in the case of oil in water is also made.     

土样含水量快速测定传感技术研究

土壤含水量的速测受土壤电导和土壤类型等诸多因素的影响，如何确保测试精度是实现土壤含水量速测的关键。首先分析了土壤含水量速测传统方法存在的问题，并从低成本快速测试的目标出发提出了实现土样含水量测试的电容传感技术、传感器结构和原理，并给出了传感器的信号检测处理电路。使用速测技术设计而成的测定仪器测试结果与常规烘干称重法对比，其精度达到土样含水量测定的要求。     

基于双二极管调制的边缘电场土壤水分传感器特性

研究了一种用于土壤水分测量的边缘电场平面传感器,设计了平面电容土壤水分传感器的双T二极管调制检测电路和数据处理系统,通过参数优化得到一种能够实现在线测试的土壤水分平面传感器及检测装置.试验表明,随着土壤含水量的变化,传感器的响应有较大的变化,且在低于25%的含水量范围内,土壤含水量与被测电压之间近似线性关系,这种平面型土壤水分传感器在农业种植方面展示了广阔的应用前景.     

液压油水污染在线连续检测传感器研究

采用聚酰亚胺水分子选择性覆膜,设计一种新型连续曲率双螺旋电容水污染传感器。分析该新型传感器的基本原理并建立数学建模,介绍其组成和软件算法流程。测试结果表明：该新型传感器可在线连续地检测液压油液中的水分,且含水率检测精度高。该传感器已成功用于液压装置的实时状态监控,为大型设备的主动维护提供依据。     

Liquid holdup measurement in horizontal oil–water two-phase flow by using concave capacitance sensor

Due to the complex flow structures of horizontal oil–water flows, the liquid holdup measurement is still a challenging problem. In this paper, we using the finite element analysis build a two-dimensional model of the concave capacitance sensor and investigate the effect of sensor geometry on the distribution of the sensitivity field. Through calculating the sensor static response for different horizontal oil–water flow patterns, we figure out the optimum geometry of the concave capacitance sensor. In addition, we conduct experiment to obtain the measured response of the concave capacitance sensor and achieve the oil-holdup by using quick closing valve. The results indicate that the optimized concave capacitance sensor shows good performance for liquid holdup measurement of horizontal oil–water two-phase flow.     

Design of a Conductance and Capacitance Combination Sensor for water holdup measurement in oil–water two-phase flow

Oil–water two-phase flow widely exists in the process of petroleum industry. The liquid holdup measurement in horizontal pipeline is very important and difficult. In this work, a Conductance and Capacitance Combination Sensor (CCCS) system with four conductance rings and two concave capacitance plates is designed and validated for its measurement performance of in situ water holdup through dynamic experiments. A set of fast electronic switches controls the conductance rings and the capacitance plates alternatively set up each own sensing field in the same sensing volume. This configuration ensures the water holdup estimation in the range from 0% to 100% regardless of flow direction. A set of quick closing valves was used to acquire the in situ holdup for the on-line calibration of the CCCS system. The theoretical correlations of conductance sensor and capacitance sensor were established to make the real-time measurement convenient. A real-time measurement method by CCCS system is provided based on the fusion of the conductance and the capacitance measurement without flow pattern recognition. This method delivers an average error of 1.06% for the CCCS system measuring the water holdup of oil–water two-phase flow, with a standard deviation of 0.038 and a relative error less than ±5%.     

Effect of humidity on the calibration of the four-terminal-pair air-dielectric capacitance standards

In this work, the effect of relative humidity (RH) on two commercial four-terminal-pair (4TP) air-dielectric capacitance standards has been measured and analyzed. The capacitance is linearly proportional to the RH under 50% owing to the dependence of the dielectric constant of air on the RH. Over 50%, a clear dielectric dispersion has been observed. It is probable that this dispersion is caused by the interfacial polarization of the adsorbed water molecules on the oxidized aluminum electrodes. In calibration aspect, it is recommended to store at least for a day to stabilize the RH inside the standard and calibrate it at RH lower than 50%. The RH coefficient of the capacitance under 50% was estimated as 3 (μF/F)/% from the measurement.     

原油含水率测量温度-矿化度简化补偿模型研究

电容法在原油含水率在线测量领域有广泛应用,然而其测量精度容易受到温度与原油中水的矿化度影响.为量化温度与矿化度对原油含水率测量的影响,提高测量精度,设计了一套基于PCAP01芯片的原油含水率测量系统,通过多项式拟合获得了温度-电容与矿化度-电容的独立补偿模型,结合温度-矿化度-介电常数补偿函数,建立了带有电极保护套的电...     

电容式三相流含水率测量方法的研究

针对三相流含水量在线测量,提出电容传感器数字化的测量原理,给出了测量电容微小变化量的具体办法.