卧式搅拌釜气液传质特性及其应用

前言国外从60年代初已开始用卧式搅气釜(Horizontal Sirrted Vessel)(见图1)作为拌体吸收传质装置。由于它在很低的搅拌转速下具有良好的气液传质特性,引起了化工界极大兴趣。起初卧式搅拌釜主要用于气体吸收以代替填充塔,后来才用于聚合反应。它是气液系聚合工艺的理想设备。有机氟单体聚合多数有一个气液传质过程。据报导国外氟聚合物生产已逐步转向采用卧式搅拌釜。     

卧式搅拌釜气液传质性能研究

在 50L卧式搅拌釜内,采用氧电极法测量纯水 O2 体系的液侧容积传质系数kLa, 研究搅拌弗鲁德数Fr、桨叶尺寸和液含量等对kLa的影响。随着Fr提高,kLa增大;桨径、桨宽、叶片数和层间距与kLa有关系,而层间夹角对kLa影响不大;随液含量的增加kLa先缓慢升高而后降低,且峰形和峰值随Fr的增大而发生变化。研究结果可供四氟乙烯等聚合釜搅拌桨设计优化和工程放大参考。     

卧式搅拌釜气液传质特性的研究(Ⅱ)

分别在纯水-O_2、乳化剂水溶液-O_2两个体系中,实测了卧式釜中长径比、桨径釜径比、液含率、搅拌桨个数、叶片数及操作条件对气液传质容量系数K_(La)的影响,关联了低Fr数区的实验结果;提出了以K_La为目标函数的放大准则:在几何相似条件下,保持Fr=const.,或P_v=const..     

卧式搅拌釜气液传质特性的研究(Ⅰ)

针对国内氟塑料生产过程技术开发的需要,用氧气物理吸收法及激光透射法测定了卧式釜液侧传质容易系数k_La及比界面积a.结果表明,与立式釜相比,卧式釜具有一系列优点:如进行正常传质所需的搅拌转速较低;在相同功耗下,传质容量系数约高一个数量级;混合程度及传质面分布均匀度有明显改善.本文用流体力学原理分析了两类釜传递特性差异的原因,并对实验结果作了关联.     

立式聚合釜气液传质特性的研究

本文旨在开发新一代聚四氟乙烯立式反应釜。分别在纯水-氧、乳化剂水溶液-氧两个体系中,用纯氧物理吸收法测定了H/D=1.27的釜的传质容量系数K_La,分析了两体系K_La差别的原因,并对实验结果进行了关联。研究表明,水体系的K_La,是乳液体系的2.5倍,桨型、安装位置等参数对传质有明显影响。在H/D≤1.27的釜中以单层三叶船舶推进器为最佳桨型。     

搅拌槽内的气液分散和传质特性

本文分两部分。分别探讨鼓泡搅拌槽内的气液分散和传质特性。在本文(Ⅰ)中。应用光纤和微机技术建立了光衰减法测定相界面积的实验装置,测定了鼓泡搅拌槽内的相界面积、气含率和传质系数。以静止、无限液体中单个气泡上升运动为基础,结合各相同性湍流理论,推导了湍流液体中单个气泡上升速度公式,通过恰当假设,应用于气泡群,得到了槽内气含率、相界面积和操作变数之间的关系,和实验结果比较,两者基本一致。在本文(Ⅱ)中,根据表面更新和湍流扩散的概念,推导了更新颇率、湍流扩散参数和操作变数之间的关系,和气含率、相界面积的公式相结合,计算了传质系数kL,和测定的实验结果比较,符合良好。     

新型气液搅拌釜式反应器

<正> 在化学工业中,用于气液混合或反应的装置较多,其中,需要气体滞留时间大于一二分钟以形成预期反应的装置,以间歇或连续的搅拌釜式反应器(STR)最为典型。一般来说,气液间的反应发生在液体或液体中的溶解物与溶解在液体中的气体分子     

三相机械搅拌反应器气液传质

由空气-水、液体石蜡-细颗粒黄沙、石英砂、催化剂构成三相体系,常压下在表观气速0.10×10^-2～1.5×10^-2cm&#8226;s^-1 、固体浓度为0～0.34 g&#8226;ml^-1溶剂、搅拌转速450～1500 r&#8226;min^-1的实验条件下,采用溶氧仪研究了三相机械搅拌反应器的气液传质特性,考察了操作参数和液体性质、颗粒粒径及密度等物性因素对液相容积传质系数k_La的影响,用改进的高斯-牛顿法进行参数估值,得到k_La与上述因素的量纲1关联式,统计检验表明,所得量纲1关联式与实验值拟合情况良好,可为后续搅拌反应釜中三相淤浆床甲醇合成过程分析与模拟提供传质基础数据.     

卧式搅拌釜放大设计

以反应器非几何相似、流体混和参数相近的放大准则设计了500L 卧式釜搅拌桨。该釜用于四氟乙烯分散聚合生产结果表明,与立式釜相比,具有反应时间短、分散液固相浓度高,树脂质量好等一系列优点。     

气体搅拌的萃取塔气—液—液系统流体力学性能和传质特性

１引言采用机械搅拌的萃取塔已广泛地应用在石油和化学工业生产中。近年来,一些研究学者又开发了用气体进行搅拌的萃取过程［１～３］,与机械搅拌相比,采用气体搅拌具有塔内无运动部件、操作稳定、结构简单、能耗低等特点,无疑给操作带来方便。如果在塔内装入静态混合...     

Mass Transfer Study of the Electropolishing of Horizontal and Vertical Rectangular Ducts under Free Convection Conditions

Rates of electropolishing of the outer surface of horizontal and vertical rectangular copper ducts were studied by measuring the limiting current of the anodic dissolution of these ducts in phosphoric acid under natural convection conditions. Phosphoric acid concentration and duct dimensions were varied to provide Sc Gr range of 1.46 × 10⁹–1.42 × 10¹¹. Under these conditions rates of polishing of vertical ducts were found to fit the equation Sh = 1.05 (Sc Gr)^0.27 while rates of polishing of horizontal ducts were found to fit the equation Sh = 0.7 (Sc Gr)^0.233 Sc^0.1. The present study recommends the use of the vertical position in practice owing to the uniformity of the hydrodynamic conditions at the four vertical planes which give rise to a uniform degree of polishing all over the duct.     

Ozone Mass Transfer in Stirred Vessel

A method is proposed and a model is developed which are capable of providing a correlation of the mass transfer coefficient k_La, with stirrer speed and gas superficial velocity. The method can be adopted for deriving a correlation which can be profitably used for ozone gas–liquid reaction both for assessing the absorption regime and for the simulation of oxidation processes which evolve according to slow reaction regime.     

侧顶复吹条件下AOD熔池内的传质特性

在120 t侧顶复吹AOD转炉1/4的水模型装置上,采用分析纯氯化钠粉剂,测定了AOD过程中液体内溶质(NaCl)的传质系数,考察了侧吹和顶吹气量、侧枪枪位及支数、粉剂(气泡)尺寸等的影响.结果表明,在本工作条件下,熔池液体内溶质的传质系数在7.31×10-5～3.84×10-4 m/s范围内;对给定侧枪支数和侧吹气量的纯侧吹过程,传质系数随相邻两侧枪间夹角的增大非线性增大;侧吹主枪气体对熔池内传质有决定性作用,顶吹气流使传质速率减小;增大颗粒(气泡)尺寸使传质系数增大;对应于实际工艺所规定的顶吹气量,7枪、22.5°和6枪、27°以及5枪、22.5°的侧枪配置均能提供较大传质速率.得到了有关的无量纲关系式.     

Heat and Mass Transfer in an Agitated Contact-Convective Heated Dryer

For the investigation of the drying process of a pharmaceutical fermentation waste and for determining specific heat and mass transfer coefficients an agitated contact-convective heated dryer was constructed. This dryer is also suitable for drying of other granular solids with high moisture content. Hence we investigated the drying of a by-product from bio-ethanol production, as well. The pilot-plant agitated dryer makes possible continuous measurement and data-acquisition. Data-acquisition of heated wall temperature, inlet and outlet air temperatures and humidity, mass reduction of the material makes possible the determination of transfer coefficients by the heat and mass balance of the dryer. The measured heat and mass transfer coefficients serve as proper input parameters for the simulation calculations.     

搅拌槽中液-液-固三相传质的实验研究

选择欧洲化学工程师协会(EFCE)推荐的典型液-液萃取体系正丁醇-丁二酸-水,加入不同粒径的玻璃珠构成液-液-固三相传质,以去离子水为连续相,正丁醇为分散相,溶质丁二酸从分散相向连续相传质. 利用电导率法测定液-液相传质系数,并考察了搅拌转速、固体质量百分含量、不同桨型(标准Rushton桨、上推式和下推式45°六折叶涡轮桨)、桨中心平面距槽底距离以及固体颗粒粒径对相间传质的影响. 结果表明,在高转速时,惰性固体粒子的存在强化液-液体系的传质. 随着惰性固体含量增大,液-液-固三相传质有一极大值. 粒径大于100 μm 的固体粒子对液-液体系传质系数影响很小. 三种桨中Rushton桨的对流传质效果最好.     

Mass Transfer Coefficients in Mechanically Agitated Gas‐Liquid Contactors

There are a large number of correlations given in literature for the prediction of volume‐related liquid‐side mass transfer coefficients in mechanically agitated gas‐liquid contactors. Significant disagreement can be observed concerning the proposed correlations, so that no single correlation exists representing all of the mass transfer data given in the literature. The observed differences can mainly be ascribed to the differences in the geometry of the system, the range of operational conditions and the measurement method used. On the basis of a comparative study of mass transfer phenomena in agitated Newtonian and non‐Newtonian aerated liquids, a critical discussion of the literature results is presented in this review article, so that final conclusions can be drawn for the k_Lα values in the different single‐ and multiple‐impeller agitated systems studied in the literature.