AN ASSESSMENT OF EXPERIMENTAL TECHNIQUES FOR THE MEASUREMENT OF BUBBLE SIZE IN A BUBBLE SLURRY REACTOR AS APPLIED TO INDIRECT COAL LIQUEFACTION

The proper design and control of an indirect coal liquefaction process plant require an accurate knowledge of bubble sizes and size distribution. Of particular importance regarding proper design is the understanding of the complicated dependence of bubble dynamics on bubble column geometry, and of the nature of the solid-liquid phases. The nature of the products and their relative proportions, on the other hand, are seriously influenced by the bubbling characteristics of the reactor because the mass transfer behavior and mixing are dependent on the bubble size and velocity distributions. This report reviews experimental techniques that have been employed to measure bubble sizes in multiphase reactors. The methods, which fall in three different categories, namely, the photographic method, the optical probe, and the electrical conductivity (resistivity) probe, are described in a historical sequence; and in each case, their unique features and design details are discussed. A general methodology of data analysis in each category is given, together with a state-of-the-art technology assessment and, finally, relative merits and demerits of the methods.     

应用电导探针法测定气泡参数

采用照相法对研制的双电导探针测定气泡参数的测量系统■进行标定,并将其用于测定槽径为(?)0.287m 的搅拌槽内的气泡运动速度、气泡大小分布。     

气-固流化床的气泡参数测定——直射式光纤探头在流化床研究中的应用

在鼓泡域中,从直射式光纤探头在二维床的测试与图像分析的结果得到气泡的平均直径与平均刺穿长度的关系为:d_b=1.6E[l]气泡的球形度为0.96。通过反射式和直射式光纤探头信号的比较表明,直射式探头的信号便于处理,并可用来测定气泡内的粒子含量。直射式光纤探头在二维床和三维床的测定结果对比表明,两种塔内的气泡行为规律一致但有明显的差异。     

柠檬酸法、氨水沉淀法和碳酸氢铵沉淀法制备的钇铝石榴石纳米粉体性能的比较

采用3种方法制备了纯相钇铭石榴石(yttrium aluminum garnet,YAG)纳米粉体。对不同方法制备的粉体的物理性能、素坯的微观特征、烧结性能和烧结体的透明性能进行了比较。结果表明：柠檬酸法制备的粉体,晶粒形状不规则,且有团聚体存在,该粉体的素坯显微结构不均匀,粉体烧结活性很差．1780℃保温3h烧结的样品的相对密度仅为79％,烧结体不透明。氨水沉淀法制备的粉体,晶粒尺寸较小,素坯的显微结构也不均匀．粉体烧结性能较好,达到完全致密化的温度为1700℃．此粉体经过1700℃保温3h真空烧结制备的烧结体呈半透明。碳酸氢铵沉淀法制备的粉体,晶粒形状为椭球形,分散性良好,该粉体素坯的显微结构均匀．样品达到完全致密化的温度仅为1450℃,此种粉体所制成的素坯经过1700℃保温3h真空烧结后,烧结体具有一定的透明度。因此．碳酸氢铵沉淀法制备的YAG纳米粉体有希望成为比较理想的制作透明YAG陶瓷的粉体。     

DYNAMICS OF BUBBLE SIZE DISTRIBUTION IN TURBULENT GAS-LIQUID DISPERSIONS

The population balance equation coupled with the proposed breakage kernel and the previously developed breakage model is applied to the analysts of bubble size distribution for non-coalescing systems in a bench-scale airlift column. Good agreement obtained between the theoretical results and the experimental data is encouraging and indicates that the model is suitable for predicting dispersion properties such as bubble size and interfacial area in turbulent gas-liquid dispersions.     

化学法测定鼓泡塔中的相界面积和传质系数

本文开发了一种新的物质，用Na2SO3溶液吸收空气中的O2，并伴有物理解吸C2H4来同时测定α和kL，以保证α和kL的测定在同一流体力学条件下进行，在单气泡时，将Na2SO3-O2-C2H4系统测得的αchem与通过气泡大小及上升速度经计算而得到的αgeo进行了比较，校核了αchem的准确性，并将此系统测得的kL,C2H4与化学法测得的kL,o2进行了比较，得知它们十分接近，且其关系符合Danckwerts模型。将该物系用于气泡群，测定了不同空塔气速下的α、kL和ε，并进行了数据关联，取得了相当满意的结果。通过对不同清液层高度下传质系数的测量，发现喷嘴附近的传质系数比全塔平均值高3－5倍，说明有相当比例的传质发生在喷嘴附近。     

CHARACTERIZATION OF THE DOWNFLOW SECTION OF AN AIRLIFT COLUMN USING BUBBLE SIZE DISTRIBUTION MEASUREMENTS

Bubble size distributions in an airlift column were investigated with an emphasis on the downflow section. Measurements have been made using direct photographic techniques in conjunction with image analysis in a split cylinder airlift column. Information extracted from these measurements includes local gas hold-up, variation of Sauter mean bubble diameter with column length, and liquid circulation velocity. An air-tap water system was studied for purposes of comparison, while effects of electrolyte concentration and viscosity were studied using salt water, and two carboxymethyl cellulose (CMC) concentrations in water, respectively. The effect of energy input was studied by varying air flow rate to produce superficial velocities ranging from 2·59 cm/s to 10·36 cm/s.     

光纤测量粒子直径的方法研究

介绍一种用光纤测量大量粒子直径的分布的方法。通过在光纤探头内的若干根光纤传输光束直接发射到被测粒子上,由设置在光纤探头内的接收装置把接收到的粒子遮挡光信号传送到光电元件;经处理,由计算机采集,然后计算出粒子运动速度、方向、直径及分布。它能精确、快速地测量大于20μm 液滴或球形粒子运动速度、方向、直径及分布。     

Measurement of bubble size distribution using a flying optical probe technique: Application in the highly turbulent region above a distillation plate

A flying optical probe technique has been developed and employed to measure bubble size above sieve trays in an air-water facility simulating cross-flow distillation (CRODIS). Despite the highly turbulent conditions occurring in the flows investigated, successful measurements were made of bubble size distributions at a series of levels above the trays. Using this technique, experiments are carried out on the CRODIS facility covering a range of gas and liquid flowrates and several tray configurations and the results are presented in this paper. Gas flowrate, sieve hole size and weir height were found to exhibit a significant effect on bubble size distribution, whereas liquid flowrate was shown to have negligible influence.     

利用荧光探针溶致变色效应研究有机改性蒙脱土的层间环境性质

利用荧光探针的溶致变色行为，研究了以不同阳离子表面活性剂处理过的化学修饰蒙脱土内腔的极性。清楚地观察到随所用表面活性剂长链碳原子数目的增多，荧光探针N，N-二甲氨基查尔酮在蒙脱土内的荧光光谱峰值波长移向短波，表明蒙脱土内腔的极性随活性剂疏水链长的增长不断减小。本工作所得结果将对具体的插层材料（包括不同极性的聚合单体或聚合物分子）在插层时选择合适的表面处理剂有所帮助。     

鲁奇加压气化炉空气点火机理的探讨

通过对鲁奇炉开车点火机理的分析探讨，归纳出开车要点，以方便操作，提高气化炉点火的成功率，缩短开车时间，提高工厂效益。     

荧光探针在测定N-异丙基丙烯酰胺共聚物最低临界溶液温度（LCST）时的扩散过程

合成了多种不同配比的N-异丙基丙烯酰胺(NIPAM)与丙烯酰胺(AM)的共聚物．研究了共聚物溶液在温度变化过程中发生的线团一胶粒转变,及荧光探针分子扩散进入疏水胶粒的动力学过程．研究了扩散过程的动力学,计算了探针对不同配比共聚物扩散过程的活化能,并进行了比较和讨论．研究表明,AM在共聚物中的比例越大,相变形成的胶粒结构就越疏松．此外值得注意的是：在采用混入法引入探针用以测定该转变点时必须注意存在的探针分子的扩散问题．     

坐便器用水量测试方法的比较

坐便器用水量是重要的检测指标,各国标准的测试方法有一些差异,而不同的测试方法对测试结果有一定的影响。在此比较了坐便器用水量测试的中国标准(GB 6952-2005)、美国/加拿大标准(ASME A112.19.2-2008/CSA B45.1-08)、欧盟标准(EN 997:2003/A1:2006)、澳大利亚标准(AS 1172.2-1999)四个标准。通过对相同样品的4种测试方法试验,得出了测试结果之间的差异性。结果表明,ASME/CSA方法的用水量(大冲和小冲)和GB方法基本一致,EN方法的用水量(大冲和小冲)比ASME/CSA和GB方法的小,AS方法的平均用水量最小。     

BUBBLE POINT PRESSURE MEASUREMENT FOR ISOTHERMAL QUATERNARY SYSTEM AND PREDICTION OF VAPOR-LIQUID EQUILIBRIUM

1 INTRODUCTIONVapor-liquid equilibrium(VLE)relations are required for practical use,such as in the designand operation of disitillation equipment.In the conventional experimental methods of vapor-liquid equilibria,some analytical instruments are applied.They are time-consuming and dif-ficult for multicomponent system because the proper method for the composition analysis isnot easy to be set up.     

COMPARISON OF APPROXIMATE METHODS FOR SOLVING NON-LINEAR CONVECTIVE DIFFUSION PROBLEMS

A comparison is made of the approximate methods of solving a high Schmidt number non-linear convective diffusion equation and boundary conditions similar to those which arise in various separation problems including reverse osmosis and directional solidification. The series expansion method gives the best agreement with exact numerical solutions. The film theory, which provides very simple results, yields surprisingly good estimates which are second in accuracy only to the series expansion. Several more sophisticated techniques including rapidly varying boundary conditions, the integral method and local non-similarity yield results of somewhat disappoinling accuracy. The linear problem, B ₂ = 0, for which exact analytical and numerical solutions exist, provides a discriminating test of the accuracy of the methods.     

涂料与涂膜物性的最新评价方法（Ⅰ）

涂料与涂膜物性检测是涂料生产和使用的重要环节。随着涂料品种及用途的不断扩大,其各种检测项目日益增多。介绍了近年来有所发展的检测项目和方法。     

单面与双面加热时窄缝流道内过冷沸腾气泡行为的比较

引　言流道几何尺寸影响到流动沸腾换热的特性 ,窄缝内的气泡动力学特征与非窄缝有很大差异 .工程技术中有许多场合应用到窄缝流动特性[1] .Rizwan Uddin等[2 ] 对单热流和双峰热流的两相流进行了稳定性分析 ,发现热流对稳定性边界图影响不大 ,而对入口过冷度等系统参数影响较大 .Yoshida等[3,4 ] 对各种工质的单管和双管内热虹吸进行了研究 ,发现单管和双管内的热虹吸及传热、流型等存在很大差异 .单面及双面加热时应该和热虹吸管内情况较类似 ,但还未见关于矩形窄缝流动沸腾单双面气泡动力学问题的研究报道 .　　在长期科研实践中 ,得到…     

METHODS FOR EFFECTIVE FLUIDIZATION OF PARTICULATE FOOD MATERIALS

Depending on the size and shape of the materials, methods employed to achieve effective fluidization during fluid bed drying varies from use of simple hole distributors for small, light weight materials to special techniques for larger and/or moist materials. This paper reviews common air distributors used in fluidized bed drying of food particulates. Also it reviews special methods of fluidizing larger irregular food particulates.     

COMPARISON OF METHODS FOR SOLVING NONLINEAR FINITE-ELEMENT EQUATIONS IN HEAT TRANSFER

We have developed two new methods for solving the finite-element heat-transfer equations with highly nonlinear boundary conditions and material properties. When compared with the more commonly employed successive substitution and Newton-Raphson procedures, the new methods speed convergence rates, increase the radius of convergence, or reduce user interaction. The first method accelerates the standard Newton-Raphson technique when the degree of the nonlinearity is known (for example, radiation boundary conditions or a prescribed temperature dependence in the thermal conductivity). The accelerated Newton-Raphson can reduce the computational time by more than 80% when compared with the standard Newton-Raphson technique. The second method employs feedback to regulate the solution algorithm during execution. Comparisons of these methods are given for several practical examples.     

METHODS FOR EFFECTIVE FLUIDIZATION OF PARTICULATE FOOD MATERIALS

ABSTRACT

Depending on the size and shape of the materials, methods employed to achieve effective fluidization during fluid bed drying varies from use of simple hole distributors for small, light weight materials to special techniques for larger and/or moist materials. This paper reviews common air distributors used in fluidized bed drying of food particulates. Also it reviews special methods of fluidizing larger irregular food particulates.