双锥旋流器内流场与颗粒运动模拟及其工业应用研究

发布时间：2018-05-04 20:07

本文选题：双锥旋流器 + 多相流　；参考：《武汉科技大学》2015年博士论文

【摘要】：水力旋流器是借助离心力场实现加速分离的高效通用设备，已被广泛应用在石油、化工、矿业、食品、造纸等众多领域。降低能耗与分离下限是现代工业发展对固液分离水力旋流器提出的更高要求，也是水力旋流器的重点发展方向之一。研究水力旋流器内多相流的流动行为，分析水力旋流器参数对其分离性能的影响规律，将为水力旋流器的优化设计提供科学依据，促进固液分离工程的发展。本文以双锥固液水力旋流器为研究对象，利用计算流体动力学（CFD）工具，模拟了双锥旋流器内多相流流场，分析了其流场特性，讨论了颗粒的流动行为，结合试验设计考察了双锥旋流器结构参数对其分离性能的影响，实现了双锥旋流器在凡口铅锌矿分级尾砂制备与单一高品位硫精矿生产中的应用。在时均化的纳维-斯托克斯方程基础上，应用雷诺应力湍流模型（RSM）、流体体积（VOF）多相流模型及混合（Mixture）多相流模型对直径100mm双锥30°（上锥体锥角）-10°（下锥体锥角）旋流器及单锥10°旋流器内液-气流场、液-气-固流场进行了数值模拟分析，并将模拟结果与实验室清水试验及分离试验进行了对比。结果显示，数值计算结果与试验结果具有较好的吻合性，证明了所选择的CFD数学模型的准确性及模拟的可靠性。对双锥30°-10°旋流器与单锥10°旋流器内的流场参数进行了对比研究，结果表明：旋流器锥体结构变化不影响流场参数的分布规律。在进料速度相同的情况下，双锥30°-10°旋流器内切向速度明显高于单锥10°旋流器，单锥10°旋流器内空气柱频繁的径向扰动使得两种旋流器内流体的径向速度大小相差不大，这种流场特性使得双锥旋流器可以达到降低分离粒度的效果。通过研究颗粒进入旋流器到形成稳定多相流场的过程中不同粒度颗粒在溢流与底流中的质量流率随时间的变化关系及不同瞬时时刻颗粒在旋流器内的体积分布特点，分析了旋流器内基于粒径大小的颗粒流动特性。结果表明：颗粒粒度越小，进入溢流管中所需要的时间越短；接近中位径粒度的颗粒在旋流器出口达到稳定质量流率所需的时间比其他粒度颗粒都要长；稳定状态下多相流流场中各粒度颗粒的分布特点是：颗粒粒度越细，越趋向于较均匀地分布于整个旋流器内，随着粒度的逐渐增大，在柱体及大锥体区域颗粒分布逐渐偏离旋流器中心并形成浓度偏析，粗颗粒紧贴在旋流器内壁呈“聚集态”的螺旋流动；旋流器内循环流中由于细颗粒的不断进入会造成一定程度上的颗粒累积，并形成一个环形的具有浓度梯度的高浓度区域，停止向旋流器内供入颗粒相，通过研究颗粒相从旋流器内流失的过程可以发现，动态循环流中不同粒度大小的颗粒具有不同的“逃逸”走向，细颗粒主要随溢流排出，随着粒度的变大，颗粒既能从溢流中排出也能从底流中排出，粒度进一步增大，颗粒只从底流中排出；模拟结果还表明：颗粒相是被连续相的径向流动夹带至溢流管中而形成的短路流；颗粒粒度越细，越快形成短路流，粒度越粗，越不会形成短路流及循环流。利用基于Yates算法的试验设计及CFD模拟，讨论了双锥旋流柱体高度、大锥体锥角、小锥体锥角、锥体接口直径等结构参数对分离粒度及能耗的影响。方差分析结果表明，对于双锥旋流器的分离粒度，影响的显著性顺序为：小锥段角度上下锥段接口直径大锥段锥角柱体高度；对于旋流器内压力降，影响显著性顺序为：柱体高度上下锥段接口直径小锥段锥角大锥段锥角，其中锥体角度对压力降、分离粒度是正影响，锥体接口直径与柱体高度对压力降及分离粒度是负影响。通过回归分析拟合了试验范围内旋流器分离粒度与压力降随结构参数变化的回归方程，相关系数分别为0.9918及0.9900。在所研究的双锥旋流器结构参数范围内，下锥段锥角10°，大锥段锥角30°，上、下锥段接口直径φ/D=0.7（D为旋流器直径），柱体高度H/D=2时，可以在较低的能耗下获得较小的分离粒度。设计了应用于凡口铅锌矿分级尾砂制备的双锥旋流器，工业应用结果表明，柱体直径相同的双锥旋流器相比于原单锥旋流器能有效降低分离粒度，，明显提高了分级尾砂的产率。在凡口铅锌矿回收单一高品位硫精矿的重浮联合工艺设计中，根据实验室试验及数值模拟计算，选择双锥旋流器作为凡口铅锌矿高品位硫精矿生产的重选设备，可优先从粗硫精矿中分选出约一半（按回收率计）硫品位46.5%以上的硫精矿产品，单一硫精矿的生产显著提升了企业的经济效益。工业运行数据表明，设备运行可靠，指标稳定。
[Abstract]:Hydrocyclone is an efficient general equipment for accelerating separation by means of centrifugal force field . It has been widely used in many fields such as petroleum , chemical industry , mining industry , food , paper making , etc . The lower limit of energy consumption and separation is the higher requirement of modern industrial development to solid - liquid separation hydrocyclone , and it is one of the important development directions of hydrocyclone .

In this paper , a double cone solid - liquid hydrocyclone is used to simulate the multiphase flow field in a double cone cyclone . The characteristics of the flow field are analyzed , the flow behavior of the particles is analyzed , and the influence of the structure parameters of the double cone cyclone on the separation performance is investigated . The application of the double cone cyclone in the production of the graded tailing sand of the vankou lead - zinc ore and the production of single high - grade sulfur concentrate is realized .

Based on the time - averaged Navier - Stokes equations , the Reynolds stress turbulence model ( RSM ) , fluid volume ( VOF ) multiphase flow model and mixed ( Mixture ) multi - phase flow model are used to numerically simulate the liquid - gas flow field , liquid - gas - solid flow field of 100mm double cone ( upper cone angle ) -10 掳 ( upper cone angle ) - 10 掳 ( lower cone angle ) cyclone and single cone 10 掳 cyclone . The results show that the numerical results have good agreement with experimental results , and the accuracy and reliability of the selected CFD mathematical model are proved .

The results show that the tangential velocity in the cyclone cone is obviously higher than that of the single cone 10 掳 cyclone , and the radial disturbance of the air column in the single cone 10 掳 cyclone makes the radial velocity of the fluid in the two cyclones not large . The characteristics of the flow field make the double cone cyclone have the effect of reducing the separation granularity .

The particle flow characteristics based on particle size in the cyclone are analyzed by studying the relationship between the mass flow rate of different particle size particles in the overflow and underflow in the process of forming stable multiphase flow field . The results show that the smaller the particle size , the shorter the time required to enter the overflow pipe ;
the time required to reach the stable mass flow rate at the outlet of the cyclone is longer than that of other particle size particles ;
The distribution characteristics of each particle in the multiphase flow field under steady state are : the finer the particle size , the more evenly distributed in the whole cyclone , as the particle size gradually increases , the distribution of the particles in the cylinder and the large cone gradually deviates from the center of the cyclone and forms a concentration segregation , the coarse particles closely adhere to the spiral flow of the inner wall of the cyclone in an " aggregate state " ;
in that circulate flow in the cyclone , due to the continuous entering of the fine particles , certain degree of particle accumulation is caused , and a ring - shaped high - concentration area with the concentration gradient is formed , the particle phase is stopped to be fed into the cyclone , the particles with different particle sizes in the dynamic circulation flow have different " escape " direction , the fine particles are discharged from the overflow as the particle size becomes larger , the particle size is further increased , and the particles are discharged only from the underflow ;
the simulation results also show that the particle phase is a short - circuit flow formed by entrainment of the radial flow of the continuous phase into the overflow pipe ;
The finer the particle size , the faster the short - circuit flow is formed , the coarser the particle size , the more the short - circuit flow and the circulation flow will not be formed .

Based on the test design and CFD simulation of Yates algorithm , the influence of structure parameters such as height , cone angle , cone angle and cone interface diameter on separation granularity and energy consumption were discussed .
The influence of cone angle on the pressure drop and the separation granularity is the positive effect on the pressure drop and the separation granularity of the cone segment of the upper and lower cone segments of the cylinder . The correlation coefficient is 0.9918 and 0.9900 respectively . The diameter of the cone angle is 10 掳 , the cone angle of the cone section is 30 掳 , the diameter of the lower cone section is 蠁 / D = 0.7 ( D is the diameter of the cyclone ) , and the height of the cylinder is H / D = 2 .

The double cone cyclone was designed and applied to the preparation of graded tailing sand of Fankou Lead and Zinc Mine . The results show that the double cone cyclone with the same diameter can effectively reduce the separation granularity and obviously improve the yield of graded tailings .

【学位授予单位】：武汉科技大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ051.8

【参考文献】