应用多孔转盘的转盘塔进行液膜分离的初步研究

采用带多孔转盘的转盘塔作为液膜分离的连续操作装置,进行了流体力学和传质特性的初步研究。实验表明:开有小孔的转盘塔板具有良好的液液分散性能和传质性能,适用于液膜分离的连续操作。     

应用开孔转盘塔进行液膜分离

本文通过无传质条件下油—水、乳化液膜—水体系开孔转盘塔连续操作试验,考察了塔型改变对x～n、u_0～n及n_γ的影响。通过乳化液膜一含酚水体系的传质试验,考察了传质对滞存率χ的影响和连续相pH值及两相密度差(△ρ)的变化对塔传质性能的影响。试验结果表明:开孔转盘塔的液液分散性能远远优于无孔转盘塔,盘上的小孔对经过小孔而上升的液滴有着良好的切割分散作用;除酚试验时,连续相的pH值及两相密度差(△ρ)对传质有影响,传质对滞存率x的影响也十分显著。     

多锥孔转盘塔在液膜萃取中的应用

液膜分离技术是一项崭新的工艺。本文在探索分离设备转盘塔设计的基础上,通过改进塔内构件—采用了多锥孔转盘,提高了传质速率,避免了返混和液泛现象,使转盘塔分离效果得到了显著提高。通过二级处理,使含酚废水含酚量达到排放标准。     

开式涡轮转盘塔内传质及流体力学的研究

在开式涡轮转盘塔内进行了液—液—固三相体系的流体力学和传质实验,结果表明,固相的加入对传质性能有很大影响,同时得出不同传质方向时的特征速度关联式。     

新型转盘萃取塔在己内酰胺生产中的应用

探讨了转盘萃取塔在己内酰胺精制中萃取效率的影响因素,影响转盘萃取塔传质性能的主要因素是级间的轴向返混和沟流。介绍了新型转盘萃取塔的设计及其在70 kt/a己内酰胺精制装置中的工业应用效果。与原装置转盘萃取塔的运行情况比较,新型转盘萃取塔内的固定环平面增加了筛孔挡板,能有效抑制转盘萃取塔内的轴向返混,提高转盘萃取塔的传质效率。     

液膜转盘塔分离废水中愈创木酚

本文用φ73、φ140和φ240mm三种不同塔径的转盘塔研究了液膜分离废水中愈创木酚的过程.考察了转盘转速、废水流量、废水和乳浊液的流比,表面活性剂Span-80添加量等因素的影响.得出了转盘转速是影响脱酚效率的主要因素,最佳转速随塔径的增大而减少.并关联了三种塔径塔的转速与塔径及转速与最小传质单元高度的关系.     

开式涡轮转盘塔用于液液固体系的性能研究

由转盘塔改型的开式涡轮转盘塔是一种新型的搅拌萃取塔,它适用于固含量较高的体系.其特点是每个转盘下方有3条叶片.选用水-煤油-石英砂体系,以丁酸为溶质,在内径52mm的塔中作流体力学和传质实验.结果表明,传质方向对液体分散相滞留率、固相滞留率和体积传质系数都有一定影响.固体颗粒的存在可降低扩散单元高度,但对传质并不总是有利.     

转盘萃取塔的改进

引　言转盘塔 (ＲＤＣ)具有结构简单、通量大、造价低、操作维修方便等优点 ,得到广泛应用 .但ＲＤＣ靠平滑转盘在全塔上、下一致地对连续相(ｃ)和分散相 (ｄ)整体输入能量造成以下问题 .( 1 )转速ＮＲ 较高 ,导致ｃ相轴向混合严重、能耗大、转轴晃动厉害 ,塔内界面张力σ大的物系更是如此 ;( 2 )液滴平均直径ｄｐ、持液率轴向分布过宽 .即进口端液滴不能被最初几块转盘充分分散 ,ｄｐ 大上升快 ,小 ,较长一塔段 (约 0 .5ｍ左右 )不能发挥有效作用 .而液滴上升过程中会被转盘不断分散 ,以至出口端分散过度 ,ｄｐ 过小、偏大 ,易过早出…     

转盘萃取塔传质单元高度的测定与影响因素的研究

在转盘萃取塔中用清水萃取煤油中的苯甲酸。通过改变转盘的转速、原料的进样流量、油层的厚度,分别测取分散相中苯甲酸的含量,求得传质单元数和传质单元高度。结果表明:转盘转速、油层厚度与传质单元高度成反比;原料的进样口流量与传质单元高度成正比。     

水车驱动式生物转盘氧传质模型的构建

水车驱动式生物转盘将生物转盘与跌水充氧相结合，实现高效充氧。经理论分析与试验校核，为水车生物转盘建立氧传质模型。将水车生物转盘充氧过程简化为跌水过程充氧和盘片转动充氧两部分，对两部分分别建立模型。跌水过程以双膜理论为基础，从物料平衡角度建立氧传质模型。盘片转动过程以体积修正系数为基础，对Kim&Molof模型进行修正，建立充氧模型。二者结合，经理论推导与试验校正得出最终的水车生物转盘充氧模型。模型结果显示，水车生物转盘充氧能力与初始溶解氧浓度、跌水高度、盘片转速、装置尺寸及温度有关。此模型的建立为其他改进型生物转盘的氧传质模型的建立提供了有效依据和参考。     

A PRELIMINARY STUDY ON LIQUID MEMBRANE SEPARATION IN ROTATING DISK CONTACTORS WITH PERFORATED DISKS

A rotating disk contactor (RDC) with perforated disks was employed for liquid membrane separation. Hydrodynamic characteristics and rate of mass transfer in the contactor were studied. Experimental results indicated that the rotating perforated disks contributed tremendously to liquid-liquid dispersion as well as to the rate of mass transfer. It is claimed, therefore, that contactors equiped with perforated disks is well adaptable to the continuous processing of liquid membrane separations     

疏水性单管陶瓷膜接触器在SO2吸收中的应用

对平均孔径200 nm的氧化锆陶瓷膜进行疏水改性与表征,并将其组装制成疏水性单管陶瓷膜接触器,采用清水作为低成本吸收液,开展了陶瓷膜接触器在废气脱硫方面应用的研究。比较了亲、疏水陶瓷膜接触器的传质性能,考察了进气流量、吸收液流量、进气浓度和吸收液温度等因素对SO₂脱除率和传质速率的影响,并对陶瓷膜接触器进行了长期稳定性测试。研究表明,疏水改性只改变陶瓷膜的表面性质（接触角达到132°）,对形貌结构影响较小;与未改性的陶瓷膜相比具有更高的脱硫效率和总传质系数。SO₂的脱除率和传质速率随吸收液流量的增加均增加;SO₂的脱除率随进气流量和进气浓度的增加而降低,但传质速率增加;吸收液温度的升高不利于SO₂的吸收;原料气中的CO₂对SO₂的脱除率影响较小。与传统的填料塔相比,陶瓷膜接触器具有更小的传质单元高度（HTU）值。陶瓷膜接触器脱硫效率高,可稳定操作,在废气脱硫方面具有良好的应用前景。     

陶瓷膜接触器化学吸收氮氧化物的传质过程与阻力分析

针对选择性催化还原技术(SCR)存在装置大、运行费用高、催化剂中毒失活等问题,将平均孔径为100 nm的Al₂O₃陶瓷膜进行疏水改性并组装成膜接触器,以NaClO₂水溶液为吸收液,开展陶瓷膜接触器在烟气脱硝领域的应用研究。考察了陶瓷膜接触器在化学吸收脱硝中的稳定性,以及气体流量、吸收液浓度、吸收液流量、吸收液pH等因素对NO脱除率和传质通量的影响,基于阻力串联模型,建立总传质系数方程。研究表明,陶瓷膜接触器在连续600 min运行过程中,NO的脱除效率及传质通量分别稳定在99%和0.038 mol·m^-2·h^-1左右。进气流量的增加会促进NO的吸收,吸收液pH=3时具有最高的氧化吸收性能,同时提高吸收液的浓度会增强NO的脱除效果。NO的传质过程同时受气、液、膜三相阻力控制,传质阻力分析结果表明,可以通过增加气体流速减小气相阻力,增加吸收液浓度同时降低pH减小液相阻力。本研究在烟气脱硝领域具有良好的应用前景。     

膜接触器及其相关过程在废水处理中的应用

膜接触器是一种通过膜作为两相之间的分离界面而实现相间传质的新型杂化膜过程,具体应用形式包括膜蒸馏、膜萃取、膜吸收、膜结构填料等.膜接触器使用微孔中空纤维膜将两流体分隔开,膜孔为两流体之间提供传质的场所.与传统接触分离器相比,新兴的膜接触器拥有分离效率高、工作范围宽、两相流速可单独控制以及结构紧凑等诸多独特的优点.文章着重于膜接触器及其相关过程在废水处理领域的最新研究成果和进展,具体分析比较了上述几种膜接触器的结构、工作原理和操作特点,充分展示了膜接触器在废水处理以及化工、医药、食品等领域特种分离中的广阔应用前景.     

中空纤维膜接触器脱碳和传质性能的数值研究

中空纤维膜吸收烟气中CO₂是一种清洁、高效、最具潜力的脱碳技术方法之一。本文建立了一个二维的中空纤维膜接触器平行逆流吸收混合气中CO₂的非润湿模型。考虑轴向和径向扩散,模拟了EEA、EDA和PZ 3种吸收剂在不同操作条件下对CO₂的脱除效果和传质性能。结果表明：脱碳性能从大到小为PZ>EDA>EEA;气相参数对脱碳和传质的影响比液相参数更显著;提高气体流速、CO₂浓度和气温,脱碳率均会下降;提高液速、吸收剂浓度和液温,脱碳率均增大,而传质速率只有在提高气温时会下降,其他参数的升高均会使其增大;应采用适当的液相参数,防止操作参数过高带来的不利影响。     

气/液膜接触分离过程及其膜材料研究

新型气液膜接触器是很多具有共同特点膜过程的总称,它使用高分子膜将两流体分隔开,膜孔为两流体提供有效传质的场所,与传统分离器相比具有许多独特的优点,日益成为分离科学研究的热点。简述膜接触器在不同气/液分离体系中的应用,针对膜吸收、膜蒸馏、膜结构填料等三种典型的气/液界面膜接触分离过程,从结构、膜材料、传质、分离效率等方面详细进行了分析和比较。着重介绍了近年来相关领域膜材料学的研究进展,如高分子膜材料、成膜方法以及膜材料的改性方法(等离子体改性法、紫外辐照法和表面涂覆改性法等)等。     

A porous carbon membrane reactor for the homogeneous catalytic hydration of propene

A porous carbon membrane contactor was studied to determine whether such a reactor could be used for homogeneous catalytic reactions. The hydration of propene, catalysed by an aqueous solution of phosphoric acid, was selected as a suitable model reaction. Experiments at high pressure and temperature were conducted in a laboratory-scale gas phase continuous reactor equipped with a flat carbon membrane contactor. It was shown that reasonably stable operation of the reactor could be achieved at high operating pressures by tailoring the porous structure of the carbon membrane and coupling the reactor with an on-line feedback pressure controller. The reactor operated in a mass transfer limited regime due to mass transfer resistance in the liquid filled membrane pores. Periodic oscillation of transmembrane pressure was shown to reduce mass transfer resistance and considerably improve the overall reactor performance.A dynamic model of the reactor was developed and the results of simulations compared favourably with experiments and the performance of a commercially operated conventional reactor employing a supported liquid phase (SLP) catalyst.     

Theoretical and Experimental Studies on Acetylene Absorption in a Polytetrafluoroethylene Hollow‐Fiber Membrane Contactor

The separation of acetylene from a gas mixture was investigated using a polytetrafluoroethylene hollow‐fiber membrane contactor and 1‐methyl‐2‐pyrrolidinone as absorbent. The effects of the gas velocity, the liquid velocity, the feed gas concentration, and the module length on the acetylene mass transfer were investigated. The results showed that the acetylene mass transfer flux increased with increasing liquid velocity, gas velocity, and feed gas concentration, but decreased with increasing membrane module length. A mathematical model was used to predict the wetting extent of the membrane and the mass transfer resistance in the acetylene mass transfer process. The wetting extent of the membrane was found to increase with increasing liquid velocity and to be effectively restrained with increasing gas velocity. The liquid phase resistance and the wetted‐membrane phase resistance controlled the acetylene mass transfer in the acetylene absorption process. The acetylene absorption efficiency was maintained at 90 % for 114 h of the C₂H₂ membrane absorption–thermal desorption cycle process.     

Use of axial dispersion model for determination of Sherwood number and mass transfer coefficients in a perforated rotating disc contactor

The mass transfer process in a perforated rotating disk contactor (PRDC) using a toluene-acetone-water system was investigated.The volumetric overall mass transfer coefficients are calculated in a PRDC column.Both mass transfer directions are considered in experiments.The influences of operating variables containing agitation rate,dispersed and continuous phase flow rates and mass transfer in the extraction column are studied.According to obtained results,mass transfer is significantly dependent on agitation rate,while the dispersed and continuous phase flow rates have a minor effect on mass transfer in the extraction column.Furthermore,a novel empirical correlation is developed for prediction of overall continuous phase Sherwood number based on dispersed phase holdup,Reynolds number and mass transfer direction.There has been great agreement between experimental data and predicted values using a proposed correlation for all operating conditions.     

Hollow fiber membrane contactor as a gas-liquid model contactor

Microporous hollow fiber gas-liquid membrane contactors have a fixed and well-defined gas-liquid interfacial area. The liquid flow through the hollow fiber is laminar, thus the liquid side hydrodynamics are well known. This allows the accurate calculation of the fiber side physical mass transfer coefficient from first principles. Moreover, in the case of gas-liquid membrane contactor, the gas-liquid exposure time can be varied easily and independently without disturbing the gas-liquid interfacial area. These features of the hollow fiber membrane contactor make it very suitable as a gas-liquid model contactor and offer numerous advantages over the conventional model contactors. The applicability and the limitations of this novel model contactor for the determination of physico-chemical properties of non-reactive and reactive gas-liquid systems are investigated in the present work. Absorption of CO₂ into water and into aqueous NaOH solutions are chosen as model systems to determine the physico-chemical properties for non-reactive and reactive conditions, respectively. The experimental findings for these systems show that a hollow fiber membrane contactor can be used successfully as a model contactor for the determination of various gas-liquid physico-chemical properties. Moreover, since the membrane contactor facilitates indirect contact between the two phases, the application of hollow fiber model contactor can possibly be extended to liquid-liquid systems and/or heterogeneous catalyzed gas-liquid systems.