用双阀体压差法自动测量快速流化床轴向空隙率分布

本工作把步进扫描压力测量改进为双阀体压差测量,应用于气—固两相流动的检测。该系统与 IBM-PC/XT 微机联接,实现了快速床内轴向空隙率分布的自动检测、数据处理和图形绘制,为了克服传感器、放大器和 A/D 转换板等环节产生的零点漂移,由计算机软件配合扫描系统实现了零点自动补偿,大大提高了测试精度。     

气固两相流固相浓度与流速的测量及可视化

气固两相流固相流率的测量是测试领域的难点之一,为了实现气固两相流固相浓度与流速的测量,阐述了电容层析成像的原理,搭建了气固两相流实验台,固相选用聚丙烯颗粒,气相为空气,固相依靠自身的重力流经实验装置,利用ITS公司的M3C电容层析成像装置对气固两相流的固相浓度、速度、质量流量进行了测试研究。实验中的浓度测量采用图像的介电常数分布像素,速度测量选择双层结构的电容传感器,利用相关测速原理,计算上下游传感器成像像素的相关性,最后由测得的速度及浓度分布计算出质量流量,测量结果与重力传感器测量的质量流量结果进行了对比,结果具有较好的一致性,测量误差小于10%,表明利用电容层析成像系统可对气固两相流参数的测量。     

气固两相流电容相关流量测量仿真研究

以气/固两相流互相关测量系统为研究对象,采用计算机仿真的方法,对由电容传感器构成的基于离散相浓度的电容互相关流速测量机理进行研究。利用ANASYS软件分析电容传感器与离散相浓度的关系;采用Monte-Carlo方法,建立气/固两相流动模型;研究＂凝固流动图型＂、＂非凝固流动图型＂,离散相浓度、粒度及速度分布对互相关测量系统的影响。     

基于CDC技术电容层析成像系统的研究

针对电容层析系统中的微小电容的检测问题,设计了一套以AD7746为核心芯片的微小电容在线检测装置,该装置是以八电极圆形管道为模型,通过电容数字转换技术(CDC)对微小电容进行检测。与传统的AC电桥测量装置相比,电容检测电路得到简化;与充/放电原理电容检测相比,不存在电荷注入和零点漂移,提高了电容检测系统的稳定性和精确性。同时利用有限元计算了灵敏度,使用线性反投影法(LBP)进行成像,该装置对实际的两相流在线检测具有非常重要的现实意义。     

基于电容层析成像技术的流化床内固相体积分数分布特性研究

针对煤清洁转化过程流化床内复杂气固两相流动特性,采用电容层析成像(简称ECT)技术,考察了流化床内玻璃珠和树脂颗粒瞬时和时均的固相体积分数分布特性。结果表明,利用不同时刻的瞬时固相体积分数等值图,可实现对截面颗粒分布的量化检测;局部时均固相体积分数沿径向呈"中心低、边壁高"的对称分布,截面时均固相体积分数沿轴向呈"下浓上稀"分布,测量结果与经典理论和实验观察相一致,表明ECT方法可以定性与定量测定流化床内气固两相流动过程固相体积分数。     

螺旋表面极板电容式传感器的灵敏场分析

气固两相流质量流量的检测和控制是工业上长期未能有效解决的难题。从工业角度出发,采用电容层析成像技术建立了一种改进型螺旋表面极板电容式传感器。通过有限元仿真的方式,分析了极板张角、管壁介电常数、管壁厚度对灵敏场分布和均匀性误差参数的影响。通过仿真分析,确定了各传感器模型参数的取值范围,为灵敏场分布的改善、传感器的优化设计和传感器系统性能的提高提供了必要的理论基础。     

基于模糊规则的多模型固相质量流量软测量

针对静电传感器无法给出颗粒质量流量绝对值以及多相流流动形态和结构变化影响传感器输出等问题,提出了一种基于分解合成的多模型加权平均的固相质量流量非线性软测量模型。在高压密相气力输送系统上,通过静电传感器获得大量试验数据,提取信号特征,利用模糊聚类算法将输入数据进行空间分区, 每一区间上用径向基函数（RBF）神经网络辨识出一个子模型, 再利用模糊推理将各子模型输出加权求和得到颗粒质量流量的估计值。该模型减小了流型对测量结果的影响,提高了测量精度。     

一种全新的消除双法兰智能差压变送器液位测量误差的方法

分析了影响液位差压变送器输出的主要因素,指出利用传统的计算零点与量程的方法产生测量误差的原因,给出一种简便、切实可行的计算双法兰智能差压变送器零点与量程方法,使其输出与实际液位在整个测量范围内相一致。实践证明:该方法不仅适用于差压变送器(法兰型和非法兰型、智能型和非智能型)的液位测量,还可以计算测量两种互不相溶混合液体界位的双法兰差压变送器的零点和量程。     

高频电容式水分快速测定仪

电容式水分传感器以频率信号作为参变量,由电容探头、高频振荡电路、分频器和金属屏蔽盒构成一体。可以用长电缆线与主机测量系统联接。传感频率信号经主机系统的采保、运算和A／D转换器处理后,由数码显示器直接指示水分值。主机系统设有温度补偿电路,通过调整热敏电阻参数来补偿温度对测量精度的影响。该仪器具有速度快、分辨率高、能排除分布电容和噪音干扰、量程宽、线性度好、应用范围广等特点。     

水煤浆管道运输过程浓度和流量监测仪设计

介绍一种基于电容传感器的浓度和流量监测系统,系统采用电容传感器对水煤浆浓度和流量进行在线监测,有效的提高了系统的稳定性。在接收部分采用了A/D转换器,并且进行数据的采集和处理,可大大提高精度和工作效率。     

电容层析成像系统中传感器状态监控和检测量在线修正

IntroductionResearches on electrical capacitancetomography (ECT)[1—3] have been done in recentyears. However, for engineering application,such as solids/gas monitoring, online calibrationcan not be implemented. Affected by the abrasionof the sensor pipe interior wall during pneumatictransport, the solids volume fraction(concentration) calculated from the reconstructedimage based on data from this sensor will be highlyinaccurate.…     

Sensor monitoring and online measurement correction in electric capacitance tomography system

The recalibration of electrical capacitance tomography (ECT) system is one of the key problems in keeping the system running steadily. However, for engineering application in solids/gas transport, online calibration can not be implemented and the data from this sensor may be unreliable due to the sensor pipe interior wall abrasion during pneumatic transport, so the solids concentration calculated from the reconstructed image based on these data will be highly inaccurate. The simulations show that, the inter-electrode relative capacitance variation of electrode pair spacing 1 is the most sensitive to the abrasion of sensor pipe interior wall, so this relative capacitance variation when the sensor is filled with air can be used as an indicator demanding offline system recalibration when the wall abrasion goes significant. Furthermore, while the pipe interior wall abrasion is not very serious, online correcting measured inter-electrode capacitance with wall capacitance variation can improve the accuracy of concentration calculation.     

Measurement of differential capacitance in solutions of low conductivity

An experimental set-up for measuring the differential capacitance at the dme for cell resistances up to several M is described. The system performance is analysed and experimental differential capacitance vs potential curves at the interface between the dme and 10⁻³, 10⁻⁴, 10⁻⁵ M NaF are presented. The method involves the measurement of the charging current when a linear sweep is supplied to the cell, utilizing positive feedback for the compensation of the cell resistance. Positive feedback for compensation is found to be especially useful for equilibrium capacitance measurements since it accelerates the attainment of equilibrium. Instrumental errors and the relation between the accuracy of the capacitance measurement and the error in compensation are discussed. The experimental results for 10⁻³, 10⁻⁴, 10⁻⁵ M NaF are compared with values expected on the basis of Grahame's data for higher concentrations. Agreement is found between experimental and calculated capacitances in the region of zero charge. In the negative polarization region experimental capacitances are lower than calculated capacitances and decrease progressively with decreasing concentrations.     

基于旋转分相单元的电容式气液两相流含液率测量

为提高电容器对含水率测量的能力,设计与其相匹配的旋转分相单元,以实现气液两相流含水率的起旋分相式电容测量。在电容传感器的测量单元基础上,增加旋转分相单元,利用气液两相流体力学理论对其结构进行设计优化,并根据实际应用条件确定分离圈数,保证气液分相效率。旋转分相单元克服了气液两相流流动形态的多样性,将体积含水率信息转换成液膜厚度信息及截面含水率信息进行测量。经实验验证,Lockhart-Martinelli截面含气率模型与实验中电容器测量截面含气率具有良好的一致性,其能够实现对体积含水率20%以内的气液两相流有效测量,体积含水率的绝对误差在±2%以内。     

碳酸钙微粉高温悬浮态气固反应器动态测试系统

根据碳酸钙微粉悬浮态气固反应试验台的试验要求 ,研制了专用的气体分析系统 ,采用了数字补偿的方法实现了反应器中物料反应过程的动态测试。实际使用表明 ,测量系统的综合精度为 2 %。这种方法可以应用到其他材料微粉的气固反应研究中     

Temperature distribution within the moving bed of rotary kilns: Measurement and analysis

Inadequacies in the temperature measurement within the moving bed have hindered a thorough understanding of the processes occurring within rotary kilns. A new measuring system, consisting of thermocouple arrays, a radio-transmitter, a radio-receiver and a computer monitor is introduced in this paper. With it, the 3D temperatures within the moving bed, as well as the temperatures of the freeboard gas and the kiln wall, can be measured and saved automatically. Experiments with sand on a co-current pilot kiln demonstrated that, in the passive layer of the moving bed, the temperatures were approximately constant in the circumferential direction. In the radial direction, however, large temperature difference was observed within the bed near the feed end of the kiln, and the difference became smaller as the bed went progressed through the kiln. This temperature measuring system can be used to obtain data over a wide range of operating conditions for use in engineering design. The obtained results may give new thoughts in theoretical modeling of heat transfer within the moving bed of rotary kilns.     

气液两相流电容传感器相浓度测量特性

为了考察两种电容传感器(对壁式及双螺旋式)测量气液两相流相浓度的适应性,搭建了垂直上升气液两相流电容传感器测量系统。实验表明对壁式电容传感器测量分辨率较差,而双螺旋式电容传感器对相浓度具有较高的分辨能力。采用时频分析方法对电容传感器波动信号进行了分析,发现两种电容传感器的时频联合表达均能清晰地表征流型运动特征,并可对流型进行有效辨识。最后,基于双螺旋式电容传感器测量信号,建立了气液两相流漂移模型,取得了对段塞流和混状流分相表观流速较好的预测结果。研究表明,双螺旋式电容传感器在气液两相流流动参数测量上具有较好的应用前景。     

基于ANSYS的气/液两相流电容相关流速测量仿真研究

以气/液两相流互相关测量系统为研究对象,采用MATLAB建模仿真方法,研究由电容传感嚣构成的基于离散相浓度的电容互相关流速测量机理.并针对电容传感器的"软场"特性,利用ANSYS软件分析电容传感器与离散相浓度的关系,采用Monte-Carlo方法建立气/液两相流流动模型,研究"凝固流动图型"、"非凝固流动图型"以及速度...