未燃煤粉在高炉内的分布特性的实验研究

对未燃煤粉在炉内的分布特性进行了二维模型实验研究·通过实验发现进入高炉的未燃煤粉主要聚积在气流流动缓慢和气流发生转折的区域或部位 ;在块状带 ,主要滞留在矿石层中·在煤气流主通道未燃煤粉难以聚积 ,对料柱的纵向透气性和压差影响不大·未燃煤粉积聚的不均匀性造成了局部横向压差增加 ,从而导致了煤气流的重新分布·特别是回旋区前方和前上方透气性恶化 ,使中心气流难以发展 ,促使软熔带向“平底的倒Ｖ型”或“倒Ｗ型”转变·未燃煤粉在高炉内的分布特性的实验研究@刘新 @陈星秋     

高炉布料过程中焦炭坍塌现象的模型研究

为了精确预测高炉炉料分布，开发了高炉布料数学模型。运用土力学边坡稳定理论，定量表示了焦炭向高炉中心的坍塌量。模拟结果与实测结果比较符合，证明此模型是适用的。结果表明，由于坍塌焦炭的积累，阻碍了矿石滚向高炉中心，明显改变了高炉边缘到中心的矿焦比。焦炭层的坍塌程度受布料模式、焦炭层的料面形状、矿石种类及配比、矿石批重和煤气流速等因素的影响，因此随着炉况的变化，焦炭层的坍塌状况也随之发生变化。     

利用ECT传感器获取高炉块状区物料分布信息

针对基于传感器二维灵敏场分布的电容层析成像技术在很多应用场合的局限性,提出了一种基于电容传感器灵敏场三维分布特性的成像方法,并对该方法应用于高炉块状区物料分布的可视化监测进行了仿真研究·结果表明,所提出的成像方法不仅可以反映物料在管道截面上的分布,还可以由二维图像的灰度值反映出物料轴向相对厚度信息,该信息可为制定相应的布料制度提供依据·     

未燃煤粉在高炉内的分布特性的实验研究

对未燃煤粉在炉内的分布特性进行了二维模型实验研究·通过实验发现进入高炉的未燃煤粉主要聚积在气流流动缓慢和气流发生转折的区域或部位;在块状带,主要滞留在矿石层中·在煤气流主通道未燃煤粉难以聚积,对料柱的纵向透气性和压差影响不大·未燃煤粉积聚的不均匀性造成了局部横向压差增加,从而导致了煤气流的重新分布·特别是回旋区前方和前上方透气性恶化,使中心气流难以发展,促使软熔带向“平底的倒V型”或“倒W型”转变·实际操作中,应采取高炉各风口均匀喷吹和疏通中心的操作方针     

电容层析成象系统敏感场的仿真

过程层析成象是一项新的两相流检测技术。针对十电极电容层析成象系统,介绍了电容层析成象的基本原理、电容传感器的结构以及数学模型,用有限元分析方法对传感器敏感场及不同流型对应的电容值进行了仿真计算。给出了十电极电容传感器不同极板组合之间的敏感场分布,为相关的图象重建算法提供了理论依据。最后根据敏感场仿真结果对图象重建过程中的图象失真和电容传感器的“软场”特性作了相关分析。     

高炉风口煤粉及回旋区焦炭燃烧过程数学模型

通过对高炉风口粉煤燃烧及回旋区焦炭燃烧过程中高炉工作环境的探讨,得出数值模拟的方法在喷煤高炉风口煤粉及回旋区焦炭燃烧研究中的必要性,回顾了前人应用数值模拟的实验方法在此方面的研究,总结出了煤粉喷吹过程气-粒两相湍流流动数学模型;煤粉挥发分热解及辐射传热数学模型;回旋区焦炭颗粒燃烧能量方程,最后提出了基于CCD技术的数值模拟边界条件设定的新构想.     

依据流型修正两相流组分含率的方法

两相流参数测量中,电容式组分含率传感器,受流型影响很大·仿真实验表明,该种传感器在测量管道气／油两相流截面含油率时,其误差高达１５％以上·流动成象可重建被测两相流体分布情况的图象,采用此处所述的依据流型修正浓度的方法,修正后的含油率误差降至５％以下·分析流型对测量的影响,导出了一个修正公式,并通过典型流型验证该修正方法的正确可行性·此修正方法同样适合其它气／液及液／液两相流·     

电容层析成像传感器软场性能分析

电容层析成像传感器的敏感场是软场,受被测介质分布的影响·以基于有限元分析的灵敏度快速计算法为工具,通过多种介质分布下灵敏度分布的计算与比较,研究了传感器的软场性能·结果表明,即便对于介电常数差异较小的气／油两相流,不同的电介质分布亦可导致灵敏度值有正、负百分之几十的变化·各处灵敏度变化不仅与管内介质分布有关,还与该点在敏感场中所处的位置有关·     

焦炭的粒焦反应性

研究了单种煤焦炭和工业配煤焦炭的粒焦反应性、反应后强度与块焦反应性、反应后强度的关系·结果表明:它们之间有良好的相关关系,并且还研究了单种煤焦炭粒焦反应性与煤质、焦炭光学组织、焦炭气孔结构参数等指标间的关系,说明粒焦反应性对煤种区分能力较好·     

电磁传感器工作原理

本文根据铁矿石、焦炭等物料的物理性质,提出了高炉炉料检测方法——电磁传感法;从电磁场与电路的联系,给出了探头输出电压与铁矿石、焦炭的有效相对磁导率的线性关系。实验结果表明,电磁传感器是一种很好的高炉炉料检测仪表。     

电容成像图像重建算法原理及评价

对现有的电容成像图像重建算法进行了综述并介绍了其原理,其中包括线性反投影法(LBP)、基于奇异值分解(SVD)的直接算法、Tikhonov正则化方法、Newton-Raphson算法、最速下降法、Landweber迭代算法、代数重建技术(ART)、同步迭代重建技术(SIRT)和基于模型的重建算法。在此基础上使用仿真和实验数据对目前主要使用的线性反投影法、基于奇异值分解的直接方法、Tikhonov正则化方法、Tikhonov迭代、投影Landweber迭代等进行了评价。对它们从电容值误差、图像误差、相关系数和耗用时间几个角度进行了比较,并对今后电容成像图像重建算法的发展方向提出了一些看法。     

基于图像分析的堆浸铀矿石颗粒参数辨识

采用数字图像处理技术对铀矿石颗粒参数进行测量,并确定铀矿石块度分布.首次将图像引导滤波器应用于矿石图像滤波,较好地滤除了图像噪声和保持矿石边缘细节信息.采用基于最大类间后验交叉熵准则的PCNN图像分割算法分割矿石图像,减少了矿石粘连现象.为了解决第一次分割后矿石粘连现象,采用基于凹点匹配的数字图像切割算法对粘连的矿石图像进行第二次分割,能有效分离粘连矿石图像.采用基于形状特征的颗粒参数测量法测量颗粒参数,提高了颗粒参数的测量精度,得到了矿石块度的统计分布图.实验数据表明,该方法测量误差较小,能满足实际需求.      

基于BP网络的同面多电极技术图像重构算法

为实现同面多电极技术对飞机用复合材料损伤区域和大小的识别,采用BP神经网络算法建立采样电容值与检测区域介电常数分布的非线性映射,利用输出灰度值实现损伤区域的图像重构.利用主元分析法对输入电容值进行降维处理.采用自适应调整学习率与动量因子方法加快了BP网络训练的收敛速度.仿真结果表明,该算法重构的损伤区域图像成像速度较快,准确度满足实现同面多电极技术对复合材料损伤区域大小和位置识别的要求.     

Concentration and angular velocity measurement in a cyclone separator dipleg using electrical capacitance tomography

Cyclone separator is one of the main parts of the circulating fluidized bed （CFB） boiler. The separation efficiency of the cyclone separator is very important to the whole boiler. Electrical capacitance tomography （ECT） is a unique measuring technique with great potential in multiphase flow measurement. Experimental studies are carried out on the measurement of volumetric concentration and angular velocity using ECT. The former is determined through image reconstruction method, and the latter is measured by cross-correlating the capacitance fluctuations caused by the conveyed solids. The distribution of void fraction in radial direction, the fluctuating characteristics, probability density function and the spectrum characteristics are analyzed. The feasibility and reliability of the method are verified by experimental results.     

利用ECT信息改进EST图像重建

提出了基于电容层析成像(ECT)与静电层析成像(EST)的双模态传感器技术.该技术应用电容层析成像重建得到的介质分布结果作为先验信息,提高了静电层析成像的图像重建精度.针对静电荷对ECT测量值的干扰进行了探讨.理论分析表明,ECT采用交流法检测电容,在高频交流激励、带通滤波方式下,微小电容检测系统可以消除颗粒感生电荷噪声的低频干扰.针对电荷灵敏场受介质分布的影响进行了研究,数值仿真计算表明,采用ECT提供的介质分布信息可修正实际流型下的电荷灵敏度,降低EST电荷分布反演的不确定度.由于EST的相对图像误差、相对电荷余量等图像重建指标均有所减小,所以图像相关性更好.     

A multiresolution reconstructive algorithm based on network theory for electrical capacitance tomography

Electrical capacitance tomography technique reconstructs dielectric constant distribution in an object by measuring the capacitances between the eletrode pairs which are mounted around this object. Because of the limitation of measurement condition, the measured data are imcomplet. This paper describes a multiresolution reconstructive algorithm which is based on network theory for electrical capacitance tomography technique. The dielectric constant distribution of flow of two components in a pipeline is reconstructed. The algorithm is as follows: Firstly, construct a rough, first level system model, and assume the dielectric constant distribution of the region to be reconstructed. After iteration, the dielectic constant of each unit can be reconstructed. Secondly, construct a finer, second level the system model and determine the initial dielectric constant of each unit in the region to be reconstructed according to related information between two levels. After iteration, the image of the pipeline's cross section can be reconstructed. The results of simulated experiments about different kinds of medium distributions show that this algorithm is effective and can converge. Supported by the National Natural Science Foundation of China Ma Ning: born in 1970, Ph. D.     

基于COMSOL的电容层析成像系统灵敏度场的计算

电容层析成像技术是检测两相流或多相流的过程检测技术,在工业领域中有着广泛的用途.要实现电容层析成像的图像重建工作必须先获得精确的灵敏度场数据,但是求取电容层析成像系统的灵敏度场矩阵十分复杂,而且编写有限元网格剖分模型的程序也相对繁琐和困难,且设定好的网格不易于快速修改.鉴于此,提出一种利用有限元软件COMSOL和电势分布来求解灵敏度场矩阵的方法.最后通过仿真实验进行了验证.仿真实验结果也证明了这种灵敏度场计算的有效性和可靠性.     

A multiresolution reconstructive algorithm based on network theory for electrical capacitance tomography

Electrical capacitance tomography technique reconstructs dielectric constant distribution in an object by measuring the capacitances between the eletrode pairs which are mounted around this object. Because of the limitation of measurement condition, the measured data are imcomplet. This paper describes a multiresolution reconstructive algorithm which is based on network theory for electrical capacitance tomography technique. The dielectric constant distribution of flow of two components in a pipeline is reconstructed. The algorithm is as follows: Firstly, construct a rough, first level system model, and assume the dielectric constant distribution of the region to be reconstructed. After iteration, the dielectic constant of each unit can be reconstructed. Secondly, construct a finer, second level the system model and determine the initial dielectric constant of each unit in the region to be reconstructed according to related information between two levels. After iteration, the image of the pipeline's cross section can be reconstructed. The results of simulated experiments about different kinds of medium distributions show that this algorithm is effective and can converge. Supported by the National Natural Science Foundation of China Ma Ning: born in 1970, Ph. D.     

Use of high-resolution X-ray computed tomography and 3D image analysis to quantify mineral dissemination and pore space in oxide copper ore particles

Mineral dissemination and pore space distribution in ore particles are important features that influence heap leaching performance. To quantify the mineral dissemination and pore space distribution of an ore particle, a cylindrical copper oxide ore sample (φ4.6 mm×5.6 mm) was scanned using high-resolution X-ray computed tomography (HRXCT), a nondestructive imaging technology, at a spatial resolution of 4.85 μm. Combined with three-dimensional (3D) image analysis techniques, the main mineral phases and pore space were segmented and the volume fraction of each phase was calculated. In addition, the mass fraction of each mineral phase was estimated and the result was validated with that obtained using traditional techniques. Furthermore, the pore phase features, including the pore size distribution, pore surface area, pore fractal dimension, pore centerline, and the pore connectivity, were investigated quantitatively. The pore space analysis results indicate that the pore size distribution closely fits a log-normal distribution and that the pore space morphology is complicated, with a large surface area and low connectivity. This study demonstrates that the combination of HRXCT and 3D image analysis is an effective tool for acquiring 3D mineralogical and pore structural data.