平板式离心机中微粒沉淀速度的测量外文文献翻译、中英文翻译

XXX设计(XX)外文资料翻译院 系专业学生姓名班级学号外文出处Journal of Engineering Physics and Thermophysics指导教师评语：指导教师签名： 年 月 日附录C：外文翻译平板式离心机中微粒沉淀速度的测量 J.G.Dueck, D.Yu.Kilimnik, L.L.Minkov, and T.Neese 摘要利用沙子和水所做的平板式离心机中微粒沉淀过程的实验数据已经表明：沉淀的相对速率并不是单调的函数，而是粒子总浓度与出现高于平均沉淀速率现象的频率之间的函数。本文讨论了微粒沉淀的测量方法，描述了实验过程，并分析了实验的系统误差。关键词：平板式离心机 沉淀 微粒 包括悬浮液在内的固相物体的沉淀或沉降现象出现在许多过程中。沉淀作用可用于水的澄清，水的净化和水的制备。它大大地减少了从液相中分离固体悬乳相过程中的问题。 沉淀或沉降作用与其他如过滤、浮选等净化水的方法相比，其优越性休现在它的操作简单、 成本低廉上。 本文设法通过实验研究乳胶体沉积并且在此过程中确定颗粒相互作用的影响。 测定沉积速度的方法。测定细颗粒沉积速度的最简单方法是追踪分离纯净液体的水 平面和沉积区域个垂直的圆柱体）,也就是充满沉积物悬浮液的区域。这种方法假设区域之间有明显的边界存在，它不一定真实存在，尤其是对于微粒乎。此外，用这种方法得到的结论是在假设悬浮液为勻质的基础上的,也就是没有经过离析。这种方法在除单分散悬浮液的情况下一定是正确的。我们记录了大 约10um大小的粒子的沉积，它的密度与载体液体（水）仅相差2-3倍，它的速度仅仅几个微米每秒。为了加快沉积过程我们可以利用别的质量力，首先，离心力对这种情况下对 测定的分析比起引入立式汽缸更困难。最初使用了通过测量随时间沿着沉积方向上两点间的压力的不同间接测量沉积速度 的方法。 测得的统计压力差与两点之间悬浮液的单位体积平均密度成比例。悬浮液或多或少的存在分层情况，我们可以观察到压力差变化曲线上的拐点；那些拐点对应于某一尺寸粒组的锋面通过测量仪的时间。就单分散悬浮液来说，沉积前锋两次通过压力已经测出第一和 第二拐点。拐点之间的距离和指示次数之间的差异使我们可以计算出沉积速度。 Bickert等人使用这种方法测量离心机中沉积速度得出许多有价值的结果。特别是某种悬浮液的浓聚物的加逮沉积的存在S经再次被证实。同时，用测压法测量不同尺寸大小的微粒的坑积速度是相对困难的，由于悬浮液的偏析一般不太明显，它的形式取多分散悬 浮液。在处理结果需要对非光滑函数进行数字求导，它是系统错误产生的一个原因。 基于对样本在流程两个拐点处的粒度分析并且适应于多分散悬浮液的情况的测定沉积速度的某个方法己经被提出。在他们的实-中Kumar等人利用了移动悬浮液的圆柱体。 液体的质量平衡公式为U0S01 -c(0) = UzSz1 - c（z）并且在流程中两个横截面处的粒子的粒度等级，Kumar等人得出不同粒度等级粒子的沉积速度,它受到z = 0点处液体的流动速度U0，横截面积S0和Sz,第i粒度等级指示器显示的粒子浓度值，和这些横截面处粒子c总的体积容量控制。凭初始横截面和横截面z处的样品加上测定 这些点处的固相的总浓度值和其中包含的各种不同直径的粒子浓度，我们可以发现第i粒度等级的沉积速度。 使用这种方法沉积前锋可以任意存在。这里出现的困难首先是由于圆柱体中速度场分布的不均勻性。尽管如此Kumar等人能够用这样的方法测量单分散和多分散悬浮液中粒 子的沉积速度，特别是对单分散悬浮液中的测量。特别是根据斯托克斯定律细粒级沉淀 物比预期速度沉淀得更快。 测量沉积速度的一个相似方法在中给出。悬浮液被以很快的速度倒入沉淀式离心 机，我们可以认为在初始瞬间悬浮液是均匀分布在转子容器内。我们可以通过与离心机轴上的管子连接的毛细血管在不同瞬间对悬浮液进行取样，通 过粒子浓度随时间变化问题的近似解产生浓度，时间和这种形式沉淀速度之间的关系式。这里的方法同样类似于Kumar等人的方法。有关采样点处讨论的粒子浓度的时变对在确定沉淀速度时有用。 离心法比圆柱体中测量法的优越性在于没有悬浮液流动。在装满溶液的转子上，我们仅仅得到固相对于外边缘的重新分布和相应的液体相对于离心机轴的位移。 通过这些方法得出的实验数据在15, 16中被讨镫。我们注意到被用在14中的研究 结果通过使用离心方法在许多方面被加强了。 实验过程。测定离心机中直径为di的粒子的沉积速度的理论基础是某一粒度等级粒子浓聚物的动力方程以及相应的初始条件和边界条件。 微小粒子的极其缓慢的移动使实验需要时间变长，并且有助于实验过程中的测量数据的误差变大。这个问题它是通过泵送悬浮液通过一个沉积柱；这样微粒子被原动力推动。然而这种方法导致相当大的对沉积速度的测量误差，此沉积速度是由于圆 柱体容积壁和圆柱中心处的悬浮液的流动速度不相等而产生的。这些误差没有考虑，这里使用了离心机。微粒子在离心力的作用下水平地移动，离心力超出重力十倍，从而可以用小于1 Pm的粒子做实验。介质保持不变。 使用离心机，当离心力超过重力大约50倍（旋转速度大约750rpm,离心机的半 径为0.08m)时管子和毛细血管将被转动。 实验开始前需要准备悬浮液，包括测量液体和固体物质（沙子，硅 的含量为98%,密度为P =2600kg/m3)的精确体积，为了获得需要的浓度。其次彻底摇匀悬 浮液。为了避免结块向悬浮液里添加了表面活性剂。 固体部分和表面活性剂的分散通过使用叶轮和超声波浴缸来完成。一旦悬浮液的准备过程结束，对其取样，得出分散粒子粒度分布初始函数。 悬浮液被以最快速度倒入已经旋转的离心机，并且容器被装满立即开始采样。实验过程中我们用2ml的容器对样品进行5-10次采样。这溶液总量对于研究悬浮液中固相总浓度和粒度分布是足够了。 总浓度是通过称重一定体积液体计算的，使用比重瓶测量悬浮液的体积精确到0.0005 ml,同时使用分析天平使称量精度达到 0.000005 go为了获得粒度分布我们使用了Mastersizer 2000设备,它的操作原理是基于测量通过悬浮液传输的散射激光束的强度分布。每个粒度等级的固相物质的浓度值从解 决散射理论逆运算方法中恢复。 利用得到的数据我们可以得到一种方法，使用这种方法实验过程中第i粒度等级粒子 的浓度是变化的。从方程式我们计算(tk + tk-1）/2时刻每个粒度等级粒子的沉积速度。 得到的质点速度和计算速度相比与斯托克斯理论相一致。分析可能存在（系统的的实验误差。除了可以通过复测法可以减少而不可以避免的统计误差外，极其重要的是只能根据分析测最过程确定的系统误差。下面我们给出一些有采样时限，粒子惯性浓度场等导致的不精确的评估。样品中浓度测定的误差。在某一时间间隔中对悬浮液进行取样。由于离心机中悬浮液浓度随着时间改变，它的浓度在离心前后不相同；因此,我们得到$个平均浓度。通 过为变浓度建立方程的解结果误差是可估算的。 表1样品中不同地方处粒子浓度的相对误差的测定 d um Mm151015200.000550.0130.050.120.2由上面表格可知，时刻t的测量误差与微粒直径的平方，离心机的旋转角速度，密度差和 测量时间成正比例，并且与悬浮液移动速度成反比。我们可以的得到表格1中不同尺寸粒子的误差估算。 因此，对于较大的粒 子的测量浓度可能远远小于实际浓度。 测量结果。为了研究疯淀过程中粒子的干涉，我们已经对不同初始浓度固相物的溶液进行了实验。粒子的形状和球体相差很大。由公式单个粒子的沉淀速度的估算，非球体系数取0.6。 最低的评定浓度等体积百分比，它取决于测量粒度分布仪器的灵敏度。悬浮液 的怜性条件确定浓度值的上界。分析实验中的样品得出依赖性的两个系列。第一系列代表实验过程中在取样点rp =0.07 m处固相总浓度方面的变化。我们可以推断悬浮液密度越大，沉积速度就越慢。根据文献，一般地与有效黏度的增加，悬浮液 密度和由沉降粒子5, 6, 17导致的液体的逆流有关。这些很容易解释，在斯托克斯公式的基础上，替代悬浮液参数的有效值。 给出的结果显示粒子中细颗粒部分任何时候的沉淀速度大于中等颗粒。沉积速度对粒度的依赖性在任何时候都是非单调 性。1-2 um粒子的沉积速度很小。只要考虑时间特性Us(d)曲线接近斯托克斯曲线，它被通过悬浮液总浓度减少说明,由于粒子减少的相互作用。 最大值的数值取决于dg/df。最近时刻进行的测量的特征为大粒度等级粒子已经沉淀， 因此dg/df的值前面时刻测量时要小。根据这点，我们得到当d=0.5和4um时与前面极不相同的曲线。最后，在实验过程中曲线最大值的退化用悬浮液随时间和粒子消失的相互作用 而下降的总浓度来解释。较小半径粒子沉淀的限制方程的可行习性。对应悬浮液不同的初始浓度，在d取值较小时，曲线变成直线， 由方程式可知它的斜率越小较大粒子的浓度就越低。结论1、我们开发了一个方法，使得测量出个别粒度等级粒子的沉积速度具有可能性，是根 据测量离心机中某点悬浮液总浓度的动态和个别粒度等级粒子的浓度来实现的。2、结果显示不同粒度对粒子在沉积速度方面的强烈影响。特别地，已经证明较小粒子 被较大粒子加速。当悬浮液浓度为10%时这个效应最明显。3、不断增长的多分散悬浮液的微粒沉淀速度反比于粒子大小的平方已经通过实验证 实。4、人们研究并发明了对浓度较大悬浮液很重要的沉淀减速机构。参考文献1. L. D. Laudou and E. M. Lilsiucs, Hydrodynamics . Moscow (1986).2 . Happel and K. Brenner. Low Rexywolds Number Hydrodynamics Russian translation, Moscow (1976).3.H. Bniuer. Grundiaga der Einphasen Mehrpliostrotmgen. Aarau und FrankAin am Miiin (1971) 4.G.J. Kynch. Trans. Farada Soc.48.,166-177(1952).译自：Journal of Engineering Physics and Thermophysics, Vol. 76, No. 4，2003 Journal of Engineering Physics and Thermophysics, Vol. 76, No. 4，2003MEASUREMENT OF THE RATE OF SEDIMENTATION OF FINE PARTICLES IN A PLATELIKE CENTRIFUGE UDC 532.584.22:53.082.13 J. G. Dueck,D，Yu. Kllimnik, L. L. Min,kov，and T. NeesseAbstract:The data of experimental investigation of the process of settling of fine particles in a platelike centrifuge have been given. The results obtained on sand and water have shown a nonmonotone character of the relative rate of sedimentation as a function of the total coiieeHtrdiion of particles and the presence of the effect of a higheMhan-average settling rate for the finest fractions. The methods of measurement of the sedimentation of fine particles are discussed, the experimental procedure is described, and systematic experimental errors are analyzed.Key words: Plate type centrifuge precipitation particles Sedimentation, or the settling of a solid phase, occurs in many processes involving a suspension. Thus, sedi-mentation results in the clarification of water, used in water purification and water preparation, which is largely re-duced to the problem of separation of the solid suspended phase from the liquid phase. Sedimentation, or settling, favorably compares with other methods of purifying water, as, for example, filtration, floatation, etc., in its simplicity of implementation and low cost. This paper try to through the experimental study latex body deposit and in the process to determine the influence of the interaction between particles. The method of determination of deposition rate. Determination of fine particle deposition velocity of the most simple method is tracking separation pure liquid level and the sedimentary area a vertical cylinder), also is full of sediment suspension area. This method has obvious regional hypothesis between boundary exists, its not real, especially for the particles. In addition, in this way, the conclusion is that the suspension as well on the basis of quality, that is without isolation. This method in addition monodisperse suspending liquid cases must be correct. We record the um 10 the size of particle deposition, its density and carrier liquid (water) are only 2-3 times, its speed only a few microns per second. In order to speed up the sedimentary process we can use other quality force, first of all, centrifugal force in this case of measurement analysis more difficult than into vertical cylinder. Originally used by measuring the time between two points along the deposit in the direction of the difference in the pressure of the indirect measurement method of deposition rate. The statistics of measured pressure difference between two points with the suspension unit volume average density in proportion. Suspension or the presence of more or less hierarchical situation, we can observe differential pressure change curve of inflection point; The inflection point corresponding to a certain size fraction of frontal through the measuring instrument of time. Is monodisperse suspension for, sedimentary forward two through the measured pressure is the first and second inflection point. The distance between the inflection point and the difference between the number of instructions that we can calculate deposition rate. Bickert, use this way to measure in a centrifuge and deposition rate that many valuable results. Especially some suspending liquid concentrations and arrest the presence of sedimentary was confirmed by S again. At the same time, with the pressure measurement of different size particles of pit product speed is relatively difficult, due to suspension of segregation generally not too obvious, its form take more dispersed suspension float liquid. In dealing with the results need to a smooth function digital derivation, it is an error system one of the reasons. Based on the sample in the process of two inflection point in particle size analysis and adapted to the more dispersed suspension of a determination of the deposition velocity method has been put forward. In their real - Kumar, etc in the use of the mobile suspension cylinder. Liquid mass balance formula is U0S0 1 - c (0) = UzSz 1 - c (z) and in the process of two cross section in particle size grades, Kumar, got a different grain size grade particle deposition rate, it is z = 0 point liquid velocity of flow U0, cross sectional area S0 and Sz, first I size level indicator shows that the particle density, and the cross section place particle c total volume capacity control. By initial cross section and cross section z place samples and test the point of the solid phase of total density and contains all kinds of the diameter of the particle concentration, we can find the first I size grades of deposition rate.Using this method can be arbitrary exist sedimentary striker. Here appear difficulties first is due to the cylinder speed field distribution is not uniformity. Even so Kumar, to be able to use this way to measure monodisperse and dispersed suspension medium grained fruit deposition rate, especially for monodisperse suspension of the measurement. Especially according to stokes law of fine grained precipitation content than expected precipitation speed faster. Measuring deposition velocity of a similar method given in the. Suspension is fast into precipitation type centrifugal machine, we can think of in the initial instant suspension is uniform distribution in the rotor container. We can through the and centrifuge shaft pipe connection capillary in different moment of suspension for sampling, pass a particle concentration with time change the approximate solution produce concentration, time and the form of the relation between deposition rate. The method is also similar to the method of Kumar, etc. The sampling point of discussion of the particle concentration of time-varying in determining the deposition rate is useful when.Centrifugation than cylinder in the superiority of the method is not suspension flow. In the full of solution of the rotor, we only get solid relative to the outer edge of the redistribution and the corresponding liquid relative to the centrifuge shaft displacement.Through these methods the experimental data obtained in 15, 16 was for the stirrups. We note that are used in 14 the results through the use of centrifugal method in many ways be strengthened. The process of the experiments. Measurement in a centrifuge diameter for di particles sedimentation velocity is based on the theory of a certain size grade particle concentrations of dynamic equation and the corresponding initial condition and boundary conditions.Tiny particles extremely slow movement make experiment need longer time, and help in the process of the measurement data of the bigger error. The problem it is through the pumping slurry through a sedimentary column; Such particles was driving force to promote. This approach, however, lead to considerable to sedimentation velocity measurement error, the deposition rate is due to circular cylinder volume wall and cylindrical center place of suspending liquid velocity of flow is not equal and produce. These error no consideration, here using the centrifuge. Micro particles in centrifugal force role launching the ground move, centrifugal force beyond ten times gravity, which can use less than 1 Pm particles do the experiment. Medium remain unchanged. Use centrifuge, when centrifugal force more than gravity about fifty times (rotational speed about 750 RPM, centrifuge half diameter is 0.08 m) and capillary tube will be rotation. Before the start of the need to prepare for the suspension, including measuring liquid and solid substances (sand, silicon content is 98%, density of P = 2600 kg/m3) accurate volume, in order to get the needed concentration. Secondly thoroughly shake the suspension float liquid. In order to avoid agglomeration to suspension added the surfactant.Solid part and surfactant dispersed through the use of impeller and ultrasonic bath crock to complete. Once the suspending liquid preparation process is over, the sampling, it is concluded that dispersed particle size distribution initial function. Suspension be to the fastest speed into have rotating centrifuge, and the container has been full of immediately start sampling. The experimental process we use 2 ml container samples for five to ten times sampling. The total solution for the suspension of solid phase total concentration and particle size distribution is enough. Total concentration is through the weighing a certain volume of liquid calculation, the use of specific gravity bottle measuring the volume of suspension accurate to + / - 0.0005 ml, and at the same time, using analytical balance make weighing accuracy reached 0.000005 mm go for particle size distribution we used Mastersizer 2000 equipment, its operating principle is based on measurement through the suspension of the transmission of the laser beam scattering intensity distribution. Each particle size grades of solid material density from the solution of scattering theory inverse method to recover.Using data from the we can get a kind of method, the use of this method in the process of the first I grain size grade particle concentration is changing. From the equation we calculated (tk + tk - 1) / 2 times each grain size grade particle deposition rate. Get the particle velocity and calculation speed compared to stokes consistent theory. Analysis of the system may be ( experimental error. In addition to through the repetition method can reduce and can not avoid the statistical error outside, very important is only according to the analysis of the measuring process certain system error. Below we give some have sampling time, particle inertia concentration field that is not accurate evaluation. In the sample concentration measurement error. In a time interval in the suspension for sampling. Because of the centrifuge slurry concentration change with time, and its concentration in centrifugal and not the same; Therefore, we get $a average concentration. Pass for variable concentration to establish equation solution results error is estimated. Table 1 samples in different parts of the particle concentration of relative error measurementd um Mm151015200.000550.0130.050.120.2 From the above table, it is known that time t measurement error and particle diameter of the square, centrifuge rotation angular velocity, density difference and measuring time into direct proportion, and suspension movement speed is inversely proportional. We can get the form 1 in the different size particles of error estimation. Therefore, for larger grain son measurement concentration may be far less than the actual concentration. Measurement results. In order to study crazy lake process particle of interference, we have different initial concentration solid content of the solution. Particle shape and sphere vary considerably. From the formula of single particle settling velocity estimation, the coefficient of sphere take 0.6. The lowest rating the concentration of the volume percentage, it depends on the sensitivity of the particle size distribution measurement instrument. Suspending liquid flow conditions to determine the upper bound of the density. Analysis of the samples that dependence of the two series. On behalf of the first series of the experimental process in sampling point rp = 0.07 m in solid phase total concentration changes. We can infer that suspension density, sedimentation velocity is slow. According to the literature, generally and effective viscosity increases, suspension density and by sedimentation particle 5, 6, 17 in liquid flow about. These are very easy to explain, in the stokes formula on the basis of alternative suspension parameter value. The given results show that particle of fine particle part at any time in the deposition rate is greater than the secondary particles. The dependence of the particle size of sedimentation velocity at any time is monotony. 1-2 um particle deposition velocity is small. As long as consider time response Us (d) curve near stokes curve, it is through the suspension total concentration to reduce explain, because particle reduce interaction. The maximum value depends on the dg/df. In recent time measurement for the characteristics of large grain size grade particles h