传质分离过程 ppt课件.ppt

化工分离过程Chemical Separation Processesclass hours : 48credits: 3.0,中文教材,刘家祺 主编，李韡、吴洪、姜忠义 参编. 化学工业出版社，2005年12月.,曾用教材,2002,1995,Textbook,J.D.Seader, E.J.Henley. Separation Process Principles,J. D. Seader,1998,2006,2002,J. D. Seader,2004,1. Development of new mathematical methods for solving large sets of nonlinear equations to obtain multiple solutions. 2. Mathematical studies of computer- aided process synthesis and design.,References-Books, Phillip C. Wankat Separation Process Engineering (2006) J.L.Humphrey, G.E. Keller Separation Process Technology (1997) Kirk-othmer Encyclopedia of Chemical Technology. 4th ed, New York, Wiley. Cary Judson King Separation processes (1980) Ernest J. Henley, J. D. Seader Equilibrium-stage separation operations in chemical engineering (1981),References-Journals,AIChE Journal, ACSChemical Engineering Science, Elsevier ScienceIndustrial & Engineering Chemistry Research, ACSChemical EngineeringTechnology, Wiley,Separation and Purification Technology，Elsevier Science,References-Journals,Journal of membrane Science,Elsevier Science,Fundamentals of various separation processes and the tools necessary for selecting the most suitable separation sequence for a required task. Equilibrium-based processes such as distillation, extraction, absorption and stripping, adsorption and crystallization as well as rate-governed processes such as membrane separation.Discussion of comparative energy requirements, economics, advantage and disadvantages of proposed separation tasks.,Course Description,Course objective,Get an overview on separation processes relevant to the chemical and process industryLearn some of these separation processes in varying degrees of detail:PrinciplesApplicationsCalculations,Chemical Separation PrinciplesContents,Chapter 1 SeparationProcessesChapter 2 Thermodynamics of Separation OperationsChapter 3 Mass Transfer and DiffusionChapter 4 Singer Equilibrium Stages and Flash CalculationsChapter 5 CascadesChapter 6 Absorption and Stripping of Dilute MixturesChapter 7 Distillation of Binary MixturesChapter 8 Liquid-liquid Extraction with Ternary Systems,Chapter 9 Approximate Methods for Multicomponent, Multistage SeparationsChapter 10 Equilibrium-based Methods for Multicomponent Absorption, Stripping, Distillation, and ExtrationChapter 11 Enhanced pproximate Methods for Multicomponent, Multistage SeparationsChapter 12 Rate-based Models for DistillationChapter 13 Batch DistillationChapter 14 Membrane SeparationsChapter 15 Adsorption, Ion Exchange, and Chromatography,Contents (contd),传质分离过程,第1章 绪论第2章 传质分离过程的热力学基础第3章 气液传质分离过程第4章 液液传质分离过程第5章 传质分离过程的严格模拟计算第6章 气固、液固传质分离过程第7章 分离过程的节能优化与集成,教学目标-Objective,利用已学的物理化学、化工原理、化工热力学、传递过程等课程中有关相平衡热力学和动力学机理，传热、传质和动量传递理论来研究化工生产实际中复杂物系的分离和提纯技术。,着重基本概论的理解，为分离过程的选择、特性分析和计算奠定基础。从分离过程的共性出发，讨论各种分离方法的特征。强调将工程和工艺相结合的观点及设计和分析能力的训练；强调理论联系实际，提高解决问题的能力。,教学要求-Requirements,掌握各种常用分离过程的基本原理，操作特点，简捷和严格计算方法，强化改进分离过程操作的途径，并了解一些新型分离技术。,讲授内容,第1章 绪论第2章 传质分离过程的热力学基础 两组分平衡计算，已知一相中的浓度，求另一相的浓度。 泡点温度、露点温度、闪蒸计算。第3章 气液传质分离过程 过程分析：e.g.精馏中温度分布、组成分布、流量分布。 简捷计算（short-cut）：确定关键组分、最少理论板、最小回流比、实际板数、实际回流比。 萃取精馏和共沸精馏特殊精馏。 气体吸收：过程分析；吸收的简捷计算。,讲授内容,第5章 传质分离过程的严格模拟计算 建立通用模型，求解三对角矩阵（泡点法，流率加合法）。第7章 分离过程的节能优化与集成 分离过程最小功和热力学效率，精馏的节能技术，分离流程优化和集成,第一章 绪 论,第一章 绪 论Chapter 1 Introduction,1.1 传质分离过程的分类 Classes of Separation Operation1.2 分离过程的研究和技术开发 Study on Separation Process and Development,主要内容及要求： 了解分离操作在化工生产中的重要性，分离过程的分类。 了解化工分离过程的研发现状和发展趋势。,What is Separation?,Basic Description of Operations,Operations are classified as key operations and auxiliary operations Key Operation: involves reaction or separationsExamples: distillation, leaching, reactor Auxiliary Operation: involves no change in chemical compositionExamples: pumps, heaters, compressors,What is Separation?,纯组分变成混合物，是熵增自发过程，反之，混合物变成纯净物则需作功。Mixing is inherent in nature: The increase in entropy associated with the randomness of a mixture lowers the Gibbs free energy.To “unmix” a solution we must overcome the entropic driving force to mix.,What is Separation?,借助一定的分离剂，实现混合物中的组分分级（Fractionalization）、浓缩（Concentration）、富集（Enrichment）、纯化（Purification）、精制（Refining）与隔离（Isolation）等的过程称为分离过程。,Why Separate？,In Human Body,Separation processes: Our life depends on these,Kidney: the perfect ultrafilter,静脉,动脉,肾小球,输尿管,Critical separations in human body,Separation of oxygen from air and of CO2 from blood in the lungsSelective removal of water and waste products of metabolism from blood in the kidneysSelective absorption of nutrients in the intestines.,In Industry,Why Separate？, 工程应用需要纯物质（如半导体材料）；Need for pure material in engineering application (semiconductors) 原料提纯； Preparation of raw materials into their components 材料加工需要纯物质；Need for pure material for materials processing 有毒有害物质或非活性物质的去除（如药物）；Need to remove toxins or inactive components from solution (drugs) 测试或检测用超纯标准品； Need for ultrapure samples for testing 混合物组成检测（如DNA检测）；Need for analysis of the components of the mixture (DNA testing) ,Separation Process,The separation process may be defined as those operations which transform a mixture of substances into two or more products which differ from one another in composition.,Analytical Separations small scale quantitative analysis,Preparative Separations small scale materials for R&D,Industrial Separations large scale economical,Example:Chromatography,Example:Centrifugation,Example:Distillation,Distillation Column,Example: Refinery of crude oil,Refinery for converting crude oil into a variety of marketable products.,Example: Production of p-xylene,Distillation,Crystallization,Example: Production of p-xylene,There are four different classes of separation process involved in the production,1. Vapor-Liquid Separation (Hydrogen recovery); 2. Distillation (Debutanizer,Regenerator,Splitter, Recover; 3. Extraction; 4. Crystallization,先修课程,物理化学、化工热力学、化工原理、传递过程化工原理（unit operations），涉及热力学（物理化学）、三传两组分精馏多组分非理想物系如何分离？,单元操作与分离过程Unit Operation vs. Separation Process,单元操作 尽管人们在1893年对单元操作就有所认识，但真正的提出是在1915年。 Arthur D Little（1863-1935）在给MIT校长的信中写到： 任何化学过程，不管规模大小，都可以认为是由一系列可以被称为“单元操作”的过程组成的。,Arthur D Little coined the term “unit operations” in 1915 to distinguish chemical engineering from all other professions and also to give chemical engineering programs a common focus, and headed up AIChEs Committee on Chem. Eng. Education which emphasized the unit operation concept along with accreditation to standardize courses in chemical engineering programs.,分离过程,“分离过程”形成一个独立领域的两个重大事件是：1984年Norman Lee组织召开的分离技术工程基础会议和1987年美国国家研究院的研究报告提出：“分离和纯化：迫切需要和现实机会”，对分离过程的定义、分类、研究目标和任务等进行了更为明确的描述。,1991年，美国化学工程师协会（AIChE）把国家项目委员会（National Program Committee）中的第二组由“单元操作组”更名为“分离组”，标志着单元操作向分离过程的过渡。,对于大学教育来说，分离过程是为数不多的带有纯粹工程特点的课程。同反应器和过程设计一样，分离过程是一门帮助化学工程与工艺专业的学生建立起工程概念的很好的课程。,Separation processes The legacy,Examples for early separation techniques,Salt by evaporating sea water 晒盐Metals extracted from ores 冶金Perfumes extracted from plants 香料提取Various drinks, medicines extracted from plants 天然饮料和药物生产Liquors distilled from plants 果酒生产,Separations in Modern Chemical Industry,Crucial in Chemical Engineering Most equipments - purifying productsChemical Plants50 - 90 % capital investment,化工厂中分离设备投资约占总投资的5090 ！,Basis of Separation,Size 尺寸Shape 形状Charge 荷电性Polarity 极性Solubility 溶解性Volatility 挥发性Mobility运动性,Distillation,Separation depends on distribution of components between gas and liquid phaseAll components distribute at equilibriumGas phase - application of heatLiquid phase - removal of heat,Absorption/Stripping,Gas mixture contacted with liquid Absorption - dissolving components of gas into liquidStripping - mass transfer goes from liquid to gas,Adsoprtion,A surface phenomenonDepends on selective binding of a solute to a surfaceUsed for:Gas separation Fractionation of industrial chemicalWaste treatmentDe-hydration or de-humidification of gasesWater purificationFractionation and recovery of biopolymers,Chromatography,Utilizes differential migration velocities of components within a separation deviceA novel separation processUsed for:Pharmaceutical and fine chemical fractionationsBioseparationEnvironmental separationsAnalysis of chemicalsDiagnosticsSample analysis for process control,Liquid Extraction,Liquid solution contacted with another insoluble liquid.Constituents distribute differently between the two liquid phases,Supercritical fluid extraction,A novel separation processUsed for:Separation and purification of oils, flavours and medicinal componentsRemoval of greasy materialConversion of azeotropic water-ethanol mixture to an anhydrous ethanolFractionation and purification of polymers,Membrane separation processes,Novel separation processesUtilizes selective barrierUsed for:BioseparationMedical separationsClarificationRecovery of cells from bioreactorsWaste treatmentGas separation,Separation processes,Liquid-liquid extraction 液液萃取Adsorption 吸附Filtration 过滤Solid-liquid extraction (leaching) 固液萃取Elution chromatography 洗脱色谱Membrane separation processes 膜分离Distillation 精馏Affinity separation processes 亲和分离Drying and evaporation 干燥和蒸发Freeze-drying 冷冻干燥Precipitation 沉淀Crystallization 结晶Electrophoresis 电泳Centrifugation 离心分离Mechanical sieving 机械筛分,Technological and use maturities of separation processes,分离过程的分类,级数：,相态：,单级、多级,固固、固液、固气、气液、液液、气气,操作方式：连续、间歇、半连续,规模：分析型分离、制备型分离、工业分离,分离方法按机理的分类,phase creation,Phase Creation,Phase Addition,Separation by phase creation or addition通过相的创造和加入来进行分离,Separation by barrier通过障碍物分离,分离过程的分类,有无传质发生：,机械分离、传质分离,处理两相以上的混合物如过滤、沉降、离心分离等。,处理均相混合物,Classificatin of Separation Operation,Mechanical Separation processes(feed consisting of more than one phase of matter and simply serves to separation the phases from one another) Heterogeneous Mixture,Mass transfer Separation processes(There is only one phase in feed) Homogeneous Mixture,SettlingFiltrationCentrifugationVortrap,SEPARATIONPROCESSES,Mechanism of Separations, UNMIXING is not a spontaneous process in nature,A process requiring no external driving force,Reduces randomness and thus the entropy of the system, Separations involve nonspontaneous processes Usually the mixture to separate is a homogeneous, single phase: If not, then often one will phase separate first, gravity centrifugation filtration.,1.1 Classifications of Mass Transfer Separation Processes,按物理化学原理的不同，传质分离可分为：,传质分离过程的分类,平衡分离过程：,速率分离过程：,借助分离剂使均相混合物系统变成两相系统，再利用混合物中各组分在处于相平衡的两相中的不等同分配而实现分离。,在某种推动力（浓度差、压力差、温度差、电位差等）的作用下，利用各组分扩散速率的差异实现分离。,如精馏、吸收、萃取、结晶、吸附等。,如微滤、超滤、反渗透、电渗析等。,Mass transfer Separation processes, Equilibration Separation Processes,If the mixture to be separated is a homogeneous single-phase solution, a second phase must generally be developed before separation, and the subsequent separation of chemical species can be achieved by employing difference in partition for different species between two phases. This second phase can be created by an energy separation agent (ESA) or by a mass separation agent (MSA).,平衡分离过程,极限程度- 热力学分离速率- 动力学,Limits:Extent = Thermodyanmics Rate = Transport,Background Material for Separations,The fundamentals that we will apply to study separations in this course involve: Materials and energy balances: conservation of energy and matterThermodynamics: phase equilibrium and solution thermodynamics Transport phenomena Chemical reaction kinetics: rate of conversion of one species to another,For the most part our analysis of various separations processes will focus on using phase equilibrium and materials and energy balances.,An MSA may be partially immiscible with one or more of the species in the mixture. In this case, the MSA is frequently the constituent of highest concentration in the second phase.,Application of an ESA involves heat transfer and/or work transfer to or from the mixture to be separated. Alternatively, a second phase may be created by reducing the pressure.,ESA & MSA,闪蒸 （Flash）部分冷凝 （Partial Condensation）精馏 （Distillation）特殊精馏 （Enhanced Distillation） 萃取精馏 （Extractive Distillation） 共沸精馏 （Azeotropic Distillation）萃取 （Extraction）、超临界流体萃取 （SCFE）吸收 （Absorption）、解吸 （Desorption）结晶 （Crystallization）吸附 （Adsorption）、离子交换 （Ion Exchange）膜蒸馏、膜萃取、双水相萃取、反胶团萃取 、变压吸附,Examples of Equilibration Separation Processes,The rate-governed separation processes is usually diffusion under the influence of a concentration field, temperature difference, electrical field, etc. A separation of species can be achieved based on difference in transport rates. Separation processes produce product streams which are the same phase of feed streams and which are miscible with one another., Rate-governed Separation Processes,速率分离过程,在某种推动力（浓度差、压力差、温度差、电位差等）的作用下，或在选择性透过膜的配合下，利用各组分扩散速率的差异实现分离。,膜分离过程示意,Membrane Separation Processes,The use of microporous and nonporous membranes as semipermeable barriers for application to difficult and highly selective separation is rapidly gaining adherents in industrial separation processes.,For the microporous membranes, separation is effected by differing rates of diffusion through the pores; while for nonporous membranes, separation occur because of difference in both solubility in the membrane and the rate of diffusion through the membrane.,Membrane Separation Mechnisms,Solution-diffusion,Restricted diffusion,Diffusion through pores,Bulk flow through pores,Diffusion through a membrane,membrane,feed,permeate,Diffusion through a membrane,membrane,feed,permeate,diffusion,Diffusion through a membrane,membrane,feed,permeate,Microporous Membrane Separation,膜分离过程的主要特点,（1）多数膜分离过程无相变，一般能耗较低；（2）一般无需另加物质，可节约资源，保护环境；（3）分离与浓缩、分离与反应可同时进行，提高过程效率；（4）通常在温和条件下进行，特别适用于热敏性物质分离；（5）适用于特殊溶液体系分离，如共沸物或近沸物；（6）膜性能可灵活调节；（7）膜组件简单，可连续操作，易与其它过程耦合，易于自控和维修，易于放大。,主要的膜分离过程,微滤（Microfiltration）超滤（Ultrafiltration）纳滤（Nanofiltration）反渗透 （Reverse Osmosis）气体膜分离（Gas separation）渗透蒸发（Pervaporation）电渗析（Electrodialysis）液膜分离（Liquid Membrane）,Membrane Materials,Membranes are usually fabricated from natural fibers, synthetic polymers, ceramics , or metals, but they may also consist of liquid films.,Membrane Modules,Solid membranes are fabricated into flat sheets, tubes, hollow fibers, or spiral-wound sheets.,板框式,管式,螺旋卷式,中空纤维式,Summary,More than 25 different separation operations are commercially important. 近30种分离操作在工业上具有重要地位。2. The extent of separation achievable by a particular separation operation depends on exploitation of the differences in certain properties of the species. 分离效率取决于组分在性质上的差异。3. The more widely used separation involve the transfer of species between two phases, one of which is created by energy transfer or the reduction pressure, or by introduction as a MSA. 依靠ESA或MSA的传质分离过程应用最为广泛。,1.2 Research and Developmentin Separation Technology,化工分离过程的特点,(1)化工分离技术的多样性 由于化工分离技术的应用领域十分广泛，决定了分离技术的多样性。 Keller于1987年总结了一些常用分离技术和应用成熟度关系图。 精馏、萃取、吸收、结晶等仍是当前应用最多的分离技术。液膜分离虽然构思巧妙，但技术上仍有局限性，仅在药物缓释等方面得到了应用。,(2)化工分离技术的复杂性 化工分离技术的多样性决定了它的复杂性。即使对于精馏、萃取这些较为成熟的技术，多组分体系大型设备的设计仍是一项困难的工作，问题是缺乏基础特性数据和大型塔器的可靠设计方法。,化工分离过程的特点,对于高温、高压、多组分和强非理想体系，不仅平衡数据和分子扩散系数难以准确计算，就连界面张力粘度等物性数据也难以求得。,催化剂和反应萃取之类的耦合分离技术的基础特性数据更为缺乏。大型塔器设计的放大的主要难度在于塔内两相流和传质特性十分复杂，数字模型尚不完善。沿用了百余年的平衡级模型虽然简单直观，但用于多组分分离过程的缺点已显而易见。,非平衡模型被称为可