单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,08-06-06,*,Special English,For Chemical Engineering&Process,By Ding Ming-jie,Department of Chemical Engineering,In August 2009,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,08-06-06,*,Part 3 Chemical engineering,Unit 13-16,Unit Operations,Part 3 Chemical engineering,The definition of Unit operations,化学工业和其他过程工业中进行的物料粉碎、输送、加热、冷却、混合和分离等一系列使物料发生预期的,物理变化,的基本操作的总称。,各种单元操作依据不同的物理化学原理，应用相应的设备，达到各自的工艺目的。,The definition of Unit operati,Part I Prelude,Chemical processes may consist of widely varying sequences,of steps,the principles of while are independent of the material being operated upon and of other characteristics of the particular system.,化学工程由不同顺序的步骤组成，这些步骤的原理与被操作的物料以及该特殊体系的其他特征无关。,being operated upon,在动手术（,wrong,）,被操作的（,right,）,Part I PreludeChemical proc,The,versatility,of chemical engineering,originates in(,起源于,),training to the practice of breaking up a complex process into individual physical steps,called unit operations,and into the chemical reactions.,把复杂的工艺过程分解成单个的物理过程（即单元操作）和多种化学反应过程的实践，导致了化学工程的通用性。,The versatility of chemical en,The unit-operations concept in chemical engineering is based on the,philosophy(,哲学,),that the widely varying sequences of steps can be reduced to simple operations or reactions,while are identical in,fundamentals(,基本原理,)regardless of(,不顾，不管,),the material being processed.,化学工程中单元操作的概念基于这种哲学观点：各种不同顺序的步骤可以减少为简单的操作或反应。不管所处理的物料如何，这些简单的操作或反应基本原理是相同的。,The unit-operations concept in,The original listing of the unit operations quoted above names twelve actions,not all of which are considered unit operations.Additional ones have been,designated(,指定,确定,),since then,at a modest rate over the years but recently at an accelerating rate.,最初列出的单元操作，引用的是上述的,十二种操作,，不是所有的操作都可视为单元操作。从那时起，许多年来以适中的速率不断,确定,(,命名,),新的单元操作，但近年来有加速的趋势。,The original listing of the un,Part II Classification of Unit Operations,Fluid flow,流体流动所涉及到的是确定任何流体的从一位置到另一位置的流动或输送的原理,.,This concerns the principles that determine the flow or transportation of any fluid from one point to another.,Part II Classification of U,Heat transfer,传热该单元操作涉及到的原理为：支配热量和能量从一位置到另一位置的积累和传递,This unit operation,deals with(,涉及到,),the principles that govern accumulation and transfer of heat and energy from one place to another.,Heat transfer传热该单元操作涉及到的原理为：支配,Evaporation,蒸发这是传热中的一种特例，涉及到的是在溶液中挥发性溶剂从不挥发性的溶质（如盐或其他任何物质）的挥发。,This is a special case of heat transfer,which deals with the evaporation of a,volatile(,挥发性的,),solvent such as water from a nonvolatile solute such as salt or any other material in solution.,Evaporation蒸发这是传热中的一种特例，涉及到的是在,Evaporation,蒸发器是利用加热来浓缩溶液，或是利用热把溶解的固体从饱和溶液沉淀析出以对之回收。,Evaporators employ heat to concentrate solutions or to recover dissolved solids by precipitating them from saturated solutions.,Evaporation蒸发器是利用加热来浓缩溶液，或是利用热,08-06-06,11,Evaporation,管式的蒸发器或是水平的或是垂直的，或长或短；液体可位于管内或管外，循环可以是自然循环或是以泵或推进器驱动的强制性循环。,The tubes may be,horizontal(,水平的,),or,vertical(,垂直的,),long or short;the liquid may be outside or inside the tubes,circulation(,循环,),may be natural or forced with pumps or,propellers(,推进器,),.,08-06-0611Evaporation管式的蒸发器或是水,08-06-06,12,长管蒸发器在该类型蒸发器中，液体以薄膜的形式在长的垂直的热的蒸发管中流动，既可用降膜式蒸发器又可用升膜式蒸发器，处理能力大，适合于低粘度的溶液。,Evaporation,Long-tube evaporator,In this type the liquid flows as a thin film on the walls of a long,vertical,heated tube.Both,falling film(,降膜,),and,rising film(,升膜,),types are used.They are high capacity units;suitable for low viscosity solutions.,08-06-0612长管蒸发器在该类型蒸发器中，液体以薄膜的,Rising film evaporator,在长管式垂直设计中，由于蒸发，液体处于在环流或膜流中，相应地，该蒸发器称之为升膜式蒸发器。,In the long tube vertical design,because of,vaporization(,蒸发,),the liquid is in annular or film flow for a,substantial(,大量的,),portion of the tube length,and accordingly is called a rising film evaporator.,Rising film evaporator在长管式垂直设,Falling film evaporator,在降膜式蒸发器，液体分布于蒸发器的顶部，然后以流体的形式向下流。,In falling film evaporators,liquids distributed to the tops of the individual and flows down as a flow.,Falling film evaporator在降膜式蒸发器,Drying,在该操作中，挥发性的液体（通常是水）从固体物质中除去。,In this operation volatile liquids,usually water,are removed from solid materials.,Drying在该操作中，挥发性的液体（通常是水）从固体物质中,Dryer,在该类型的干燥器中，干燥气以足够的速率通过固体床层，以使床层保持在流化状态，该流化状态可提高很大传热和干燥速率。,Fluidized bed dryers,In this type of dryer,the drying gas is passed through the bed of solids at a,velocity(,速率,)sufficient,（足够的）,to keep the bed in a fluidized state;which promotes high heat transfer and drying rates.,Dryer在该类型的干燥器中，干燥气以足够的速率通过固体床层,Dryer,流化床干燥器适合于粒状大小范围，为,1,3,的粒状和晶体状物质。该干燥器可设计为连续操作和间歇操作。,Fluidized bed dryers,Fluidized bed dryers are suitable for,granular(,粒状的,),and crystalline materials within the particle size range 1 to 3 mm.They are designed for continuous and batch operation.,Dryer流化床干燥器适合于粒状大小范围，为13的粒状,Dryer,喷雾式干燥器一般适合用于液体和稀的泥浆进料，但是可通过设计以处理任何能用泵输送的物料。放置于垂直的圆柱形容器的要干燥的物料，在一喷嘴中或在一圆盘状的原子化器中原子化。,Spray dryers,Spray dryers are normally used for liquid and dilute,slurry(,泥浆,),feeds,but can be designed to handle any material that can be pumped.The material to be dried is,atomized(,原子化,),in a nozzle,or by