搅拌槽内固液悬浮和气液分散的实验研究

在实验室提出的新型三相搅拌槽——自吸式龙卷流型搅拌槽中,采用六直叶圆盘涡轮桨进行三相混合性能的实验。从固液悬浮、气液分散和传质性能等方面对搅拌槽进行了研究,探讨了固相颗粒对气含率和传质性能的影响,得到了搅拌槽中不同性能参数的变化规律。结果表明:自吸式龙卷流型搅拌槽作为一种新型的三相搅拌槽,能够获得良好的固液悬浮和气液分散效果;当搅拌槽内固相体积分率较低(φ<20%)时,可采用颗粒的壁面堆积高度作为完全悬浮状态的判定标准;固相颗粒的存在会使气含率明显降低,但对传质性能的影响较为复杂,φ<5%时的体积传氧系数K L a高于纯溶液,φ>5%时的K L a低于纯溶液,但都随固相体积分率的增加而降低。     

搅拌槽内固液悬浮和气液分散的实验研究

在实验室提出的新型三相搅拌槽——自吸式龙卷流型搅拌槽中,采用六直叶圆盘涡轮桨进行三相混合性能的实验。从固液悬浮、气液分散和传质性能等方面对搅拌槽进行了研究,探讨了固相颗粒对气含率和传质性能的影响,得到了搅拌槽中不同性能参数的变化规律。结果表明:自吸式龙卷流型搅拌槽作为一种新型的三相搅拌槽,能够获得良好的固液悬浮和气液分散效果;当搅拌槽内固相体积分率较低(φ20%)时,可采用颗粒的壁面堆积高度作为完全悬浮状态的判定标准;固相颗粒的存在会使气含率明显降低,但对传质性能的影响较为复杂,φ5%时的体积传氧系数K L a高于纯溶液,φ5%时的K L a低于纯溶液,但都随固相体积分率的增加而降低。     

搅拌釜内液固悬浮体系的浓度分布

在120°锥底、内径为φ700mm、φ250mm 的有机玻璃釜中,采用直接取样称重法研究了液固系搅拌釜内桨的结构、桨的位置及转速、固含量、物系性质等因素对釜内固相浓度分布的影响,同时用两区沉降扩散模型对实验数据进行分析,得到了固相悬浮质量与操作条件的关系,并提出了均匀悬浮的判据,为放大设计搅拌反应器提供了可行的理论依据。     

搅拌釜内液固悬液体系的浓度分布

在１２０°锥底、内径为φ７００ｍｍ、φ２５０ｍｍ的有机玻璃釜中，采用直接取样称重法研究了液固系搅拌釜内桨的结构、桨的位置及转速、固含量、物系性质等因素对釜内固相浓度分布的影响，同时用两区沉降扩散模型对实验数据进行分析，得到了固相悬浮质量与操作条件的关系，并提出了均匀悬浮的判据，为放大设计搅拌反应器提供了可行的理论依据。     

五层帆布板在空气输送斜槽上的应用

本厂生料车间,是由φ2.4×13米管磨和φ2.5米旋风式选粉机组成的闭路循环生产系统。成品生料经由3—φ6.5×15.5米搅拌仓搅拌后送入3—φ8×20.5米储存仓储存。自生料入搅拌仓到送入窑尾提升机,水平输送距离为121米,全部采用新型透气材料——五层帆布板的B315空气输送斜槽。经过2000多     

风动搅拌生料粉的试验

镇江水泥厂新建车间的工艺设计中采用了风动搅拌生料粉的新技术。搅拌库规格为φ6.5×15.00米,2个,自建成投产以来,使用效果良好。该库的设计是在φ1.30×4.23米试验库试验成果的基础上进行的,现将有关试验情况介绍如下:     

自吸式三相搅拌釜中流动与传质特性实验研究

以CFD数值模拟为基础,从功耗性能和体积传氧性能两方面,对自吸式三相搅拌釜中流动与传质特性进行实验研究。实验表明,当搅拌转速低于气体吸入临界转速时,其对搅拌功率的影响很小,当转速高于气体吸入临界转速时,随着固相分率的增大搅拌功率下降。当固相分率φ<5%时,固相颗粒的存在使得体积传氧系数KLa增大,当固相分率φ>5%时,固相颗粒的存在使得KLa降低。单位体积功耗Pg/V越大,KLa越大,同样的单位体积功耗下,自吸式三相搅拌釜的KLa比搅标准搅拌釜高。     

液-液搅拌系统的相转换特性

本文从工程放大与设计角度研究了液—液搅拌的转相特征。转相与单位质量流体的搅拌功率有关。对本实验物系,转相的设备尺寸效应可用经验式φ_c,上=0.62+0.17/(N~3D~2)~(0.77)表达。研究操作方式对转相影响表明,过程连续化后,只要合理安排进出料位置,满足φ(?)=φ_0=φ_T,则转相与物料停留时间无关,转相规律与间歇操作相一致。     

国外聚乙烯固相氯化工艺研究概述

本文概述了国外聚乙烯固相氯化方式的研究工作,扼要介绍了固相氯化工艺条件研究的进展情况。 国外聚乙烯固相氯化方式主要有四种:流化床、转动床、固定床和搅拌床,其中搅拌床固相氯化方式是PE固相氯化工艺研究和发展的方向。国外认为采用搅拌式固相氯化方式,以HDPE为原料,用含适量H_2O的Cl_2作氯化剂,TiO_2或SiO_2为防粘剂,以羧酸酐为增白剂,采取热处理或分段氯化工艺条件,完全有可能得到性能良好的CPE,使聚乙烯固相氯化工艺达到工业化生产的要求。     

高速混合制粒机的实验研究

对固体颗粒在高速混合制粒机内的搅拌混合进行了试验。试验为固定一个物料体系 ,进行三因素 (主搅拌桨转速、制粒桨转速、混合时间 )三水平的正交试验。研究了主、辅搅拌桨转速及混合物料物性对混合效果的影响。从实践上分析了混合效果与各结构参数及操作参数的关系。通过找出最佳混合参数组合 ,给出最适混合转速及最适混合时间     

气液向下并流填料塔的持液量

用φ15mm的陶瓷拉西环和塑料鲍尔环填料,在内径153mm的有机玻璃塔内,采用空气-水体系,测量了气液向下并流流动时的持液量数据。以Bemer等人提出的颈缩管模型为基础,推导了向下并流填料塔内的持液量计算式,较好地关联了本实验和Dodds等人的结果。并检验Larkins,Charpentier,佐藤等人提出的持液量关联式。     

Some characteristics of a sparged agitated vessel under foaming — Mechanical control of foaming —

Foam-breaking with a rotating disk mechanical foam-breaker (MFRD) was studied for a foaming system containing a diluted detergent solution in a laboratory sparged agitated vessel. The change of the foam-breaking capacity of the MFRD by varying the air sparge rate, the working volume and the impeller speed or the disk diameter was measured. Based on these measurements, empirical equations are presented for predicting the critical foam-breaking regions of the MFRD fitted with the agitated vessel. The operational range where foam-breaking with the MFRD can be carried out effectively and economically is also discussed.     

Mixing in mechanically agitated gas-liquid contactors,bubble columns and modified bubble columns

Mixing time measurements were made in 300 and 1000 mm i.d. mechanically agitated contactors with different types of impellers, located at different heights from the bottom of the vessel. Mixing time measurements were also made in 150, 200, 385 and 1000 mm i.d. bubble columns with varying liquid heights. Transient pH measurement and conductivity measurement were used to measure the mixing times. Impeller speed was varied in the range of 3.33–20 r/sec in the case of mechanically agitated contactors and gas superficial velocity was varied in the range of 10–250 mm/sec in bubble columns. Effect of physical properties of the fluid (surface tension, ionic strength, liquid viscosity) and that of the non-Newtonian behavior on mixing time was studied. Mixing time in the presence of drag reducing agents was also investigated.In the range of variables covered in this work mixing time in mechanically agitated contactors and bubble columns was found to be in the range of 4–6Mixing time predictions based on the longest loop length and circulation velocity are made in the presence and absence of a gas for mechanically agitatA procedure is given for the prediction of the critical impeller speed for gas phase dispersion in mechanically agitated contactors.     

螺旋桨搅拌槽中液体的流动结构

在直径１６００ｍｍ的平底柱形有机玻璃槽中，利用热膜风速仪测量了２个搅拌浆－槽体系中流体的时均速度，脉动速度的均方根值，湍流强度，纵向积分尺度，纵向微分尺度和能谱函数。研究了时均速度及湍流微结构在搅拌槽中的分布规律及搅抖转速的影响。     

湿烟气工况下齿形螺旋翅片管束的性能研究

换热器烟气侧自身结构参数和外界条件是影响换热器换热及阻力特性的主要因素，采用数值模拟和实验方法研究了翅片螺距及烟气含水量对齿形螺旋翅片管束换热及阻力特性的影响。结果表明，在翅片螺距3.63～8.47 mm范围内，烟气侧 Nu随着翅片螺距的增大而增大，在不同入口烟温下，相对于3.63 mm翅片管，5.08 mm和8.47 mm翅片管 Nu分别增大3%~6%和9%~14%， Eu随着翅片螺距的增大而减小，相对于3.63 mm翅片管，5.08 mm和8.47 mm翅片管 Eu分别减小30%和50%左右；烟气含水量的适当增大，有利于提高齿形翅片管束的换热及阻力特性。     

充气条件下多层桨悬浮颗粒的临界转速

在直径为386 mm 的通气多层桨搅拌釜中,实验考察了下层搅拌桨型、挡板和气体分布器等对颗粒悬浮临界搅拌转速的影响,这对工业过程的设计和放大具有一定的指导意义.     

18.4-38 10PR农业驱动轮轮胎的设计

介绍18．4—3810PR农业驱动轮轮胎的设计。结构设计：外直径1730mm，断面宽445mm，行驶面宽度424mm，弧度高42mE，胎圈着合直径970mm，胎圈着合宽度406．5mm，断面水平轴位置（H1／H2）0．784。采用一大一小排列的人字形胎面花纹，花纹深度38mm，花纹饱和度32．5％，花纹周节数30。施工设计：胎面采用冠部胶冷喂料挤出缠绕法、两块胎侧冷贴方式，胎体采用6层高强度1870dtex／2锦纶6浸胶帘布（4V1＋2V2），钢丝圈采用φ0.96mm的19#回火胎圈钢丝，采用LCB-4A成型机成型、短柱塞式硫化罐硫化。成品轮胎试验结果表明，轮胎的外缘尺寸和物理性能均符合国家标准要求。     

改善气液传质的新型表面曝气装置

A novel surface aeration configuration featured with a self-rotating and floating baffle (SRFB) and a Rushton disk turbine (DT) with a perforated disk has been developed. The SRFB, consisted of 12 fan blades twisted by an angle of 30° to the horizontal plane, is incorporated onto the impeller shaft to improve gas entrainment, bubble breakup, mixing in a φ154 mm agitated vessel. This new configuration is compared to the conventional DT surface aeration experimentally. The results suggest that the critical impeller speed for onset of gas entrainment is lower for the new configuration and it demands greater power consumption. Moreover, the SRFB system produces 30%-68% higher volumetric mass transfer coefficient per unit power input than that obtained in the conventional DT surface aerator under the same operation conditions.     

A general enhancement factor model of the physical absorption of gases in multiphase systems

A general mass transfer enhancement factor model (GEFM) has been developed based on the enhancement mechanism proposed in this paper taking both shuttle effect and hydrodynamic effect into account to calculate the overall enhancement factor due to the presence of dispersed particles. GEFM can describe the phenomena of the enhancement factor increasing with partition coefficient (m), surface covering fraction (α) and dispersed phase volume fraction (φ) increase, leveling off at higher φ, changing of enhancement factor (E) at different conditions. Moreover, GEFM can give the enhancement factor not only of multiphase system relative to the pure liquid phase (even at quite high φ), but also in the same system under different conditions (e.g. stirrer speed, viscosity). The enhancement factors predicted from GEFM are consistent with the experimental observations well.     

Effect of system properties on the performance of Liquid—Liquid extraction columns—II: Oldshue—Rushton column

Mean drop size, fractional hold-up of dispersed phase and axial mixing characteristics have been determined in a 72 mm diameter mechanically agitated extraction column of Oldshue—Rushton type, using the two liquid—liquid mass transfer systems, toluene—acetone—water and MIBK-acetic acid—water. As for normal conditions of packed column operation described in Part I, solute presence and the direction of mass transfer has a significant effect on mean drop size, fractional hold-up and to a lesser extent, axial mixing in the dispersed phase. Probably the most dramatic effect however is the manner in which solute transfer affects dispersed phase behaviour. Highly coalescing conditions with transfer from the dispersed to the continuous phase can make the column practically unoperable. As for the packed column, axial mixing in the continuous phase is unaffected except in so far as solute presence and direction of mass transfer affect the hold-up of dispersed phase.