【作者】 王勇；

【导师】 李宝彦；

【作者基本信息】 大庆石油学院 ， 化工过程机械， 2006， 硕士

【摘要】 混合操作是极其普遍而又重要的过程,如气-液接触、萃取、反应、传热等都与混合有关。静态混合器是一种新型开发的单元设备,国内在这方面起步比较晚,通常在制造方面多是仿造其它国家的设备,并没有对静态混合器本身的混合机理作过深入的研究。本文旨在对静态混合器的混合机理作深入研究,这一研究的最终目的旨在提高静态混合器的混合效率,并为设计制造提供一定的理论基础。本文对静态混合器内的流场的混合机理进行了研究。研究表明,流体在静态混合器内有两种流动形态,层流和湍流。层流时,是“分割、位置移动、重新汇合”的三要素对流体进行有规则和反复的作用,以达到混合。湍流时,除以上三要素外,流体在流动断面方向产生旋涡,使细微流体分割,然后再混合。通过计算管内流场的涡量方程,绘制涡量随时间的变化曲线,定性得出:涡量随着时间和位置的移动不断衰减。静态混合器内流场分布属于不可压粘性流动分布。通过理论计算表明,其速度分布满足纳维-斯托克斯方程,并在低雷诺数的情况下,方程为线性方程并有其精确的解析解。对流体在静态混合器流动的运动和力进行了研究。研究表明,流动物料经过静态混合器时,有四个基本的运动:料流的分割;料流改变方向;料流的内外侧置;向后再混合。有三种力影响着液滴的形成,即剪切应力,液体的表面张力,分散相中的粘性应力。在湍流状态下,剪切应力和液体的表面张力是决定液滴大小的主要因素,粘性应力常常可以忽略。对静态混合器水力参数和压力降进行了计算。计算表明,静态混合器的压力降是空管的数十倍,同时阻力大小随流动速度和粘度而变化;组件螺旋角,组件前后边缘的光滑程度,组件的形状偏差和相邻组件的连接状况等对流动阻力也有影响;摩擦系数与组件数的多少无关。对流体的传热机理进行了研究。研究表明,无论混合管内的流体处于何种流动状态,传热边界层均为层流边界层。通过总结管内层流边界层的能量方程并求解该能量方程得出传热准数与边界层长的理论计算式。通过实验曲线发现,混合单元数对静态混合器的混合效果挺重要。当混合组件数超过四以后,静态混合器出口处的速度脉冲值趋于常数,即混合组件太多时,已无法进一步增加流体的湍流强度。流体的混合度唯一由混合器内的单元数决定,而与流体的速度、粘度和压力无关。最后通过分析传统静态混合器的不足,理论上设计出了一种低剪切、高性能的静态混合器。更多还原

【Abstract】 Mix operation is used widely and it is an important process. Such as gas-liquid touch ,extraction, reaction, heat transfer are connected with mix.Static mixer is a new kind equipmentin our country.It’s development is late and many equipment are simulated .Comprehensivemethod is not reported.This paper aims to study principle of static mixer.The final purpose aimsto improve efficience of static mixer and offer basic theory to design and produce.This paper show that mix principle includes and onflow. When it is laminar flow, it is“comminute, position movement, converge “over again, which has some effect regular anditerative to fluid. When it is onflow, besides above three element, because fluid can producedrastic vortex in the section of flow, so it has very strong cut force to fluid, which makes littlepart divided, then mix again. By computing vortex equation and drawing curve, conclusion isdraw that vortex becomes augment ,then becomes attenuation with time and distance.The flow distributing belongs to no press glutinosity flow . It’s velocity distributing is fitfor N-S equation ,and under condition of low Re, this equation is linear equation and hasaccurate result.There are four basic movement.By Analyzing movement and force,there are three force,cutstress,surface tension and glutinosity stress affected to form little drop.Under onflow,surfacetension is the main factor to decide little drop,while glutinosity is often ignored.The fluid resistance is ten times to the hollow pipe.By computing waterpower andresistance. It is caused by the increase of resistance inside pipe, at same time resistance changeswith velocity and glutinosity. The front and back fringe velvet degree of element, the shapediscrepancy of element and joint condition of adjacent element have some effect to flowresistance;Friction coefficient is not collected with element numbers.By analyzing heat transfer principle,whatever flow state is there in the static mixer,heattransfer border is laminar flow border.By analyzing energy equation of laminar flow andsolving this equation ,theory equation is got.By abundant experiment study inside Kenics static mixer ,number of element is veryimportant to static mixer.When the number of mix element exceeds four,velocity pulse tends tobe constant in the outlet of static mixer.In other words ,when there are many mix element,vortexintensity is not increased. The mix degree is only decided by numbers of element .It is notconnected with velocity, glutinosity and press. Finally,by analyzing disadvantage of traditional static mixer ,a new kind static mixer withlow cut and high efficiency is designed on theory base.更多还原