英文翻译蒸馏.docx

1、英文翻译蒸馏Distillation 蒸馏 Separation operations achieve their objective by the creation of two or more coexisting zones which differ in temperature pressure, composition and or phase state Each molecular species in the mixture to be separated reacts in a unique way to differing environments offered by t

2、hese zones Consequently as the system moves toward equilibrium each establishes a different concentration in each zone and this results in a separation between the species 分离过程通过形成在温度、压力、组成和相态上有区别的两个或多个共存区来达到它的目的。每一种待分离的在混合物中的分子种类以一种独特的17方式与这些区域提供的不同的环境相互作用。结果是随着系统向平衡移动 每个物质都在每个区域形成不同的浓度 这样就可以使这些物质的

3、到17分离。 The separation operation called distillation utilizes vapor and liquid phases at essentially the same temperature and pressure for the coexisting zones Various kinds of device such as dumped or ordered packings and plates or trays are used to bring the two phases into intimate contact Trays a

4、re stacked one above the other and enclosed in a cylindrical shell to form a column Packings are also generally contained in a cylindrical shell between hold-down and support plates 利用在共有区中拥有相同温度和压力的汽油和液相的分离操作叫做分离。不同种类的装置例如规整填料和乱堆整料和塔板或塔盘被用来使两相充分接触。塔盘是一个堆着一个排列的并且被装入到一个圆柱形的外壳中形成一个塔。填料通常也被装入一个在压具板和支撑板

5、之间的圆柱形外壳中。 1 Continuous Distillation The feed material which is to be separated into fractions is introduced at one or more points along me column shell Because of the difference in gravity between vapor and liquid phases, liquid runs down me column cascading from tray to tray while vapor floats up

6、the column contacting liquid at each tray. 1、连续蒸馏 将要被分离成馏分的进料通过一个或多个沿着管壳的点被引入到塔中。由于气相和液相之间重力的不同，液体在塔中从一个塔盘到另一个塔盘呈阶梯形向下流动。同时气体在塔中向上流动并与液相在每个塔盘接触。 Liquid reaching the bottom of the column is partially vaporized in a heated reboiler to provide boil-up which is sent back up the column The remainder of t

7、he bottom liquid is withdrawn as bottoms or bottom product Vapor reaching the top of the column is cooled and condensed to liquid in the overhead condense Part of this liquid is returned to the column as reflux to provide liquid overflow. The remainder of the overhead stream is withdrawn as distilla

8、te, or overhead product. 液体到达塔底被一个加热的再沸器部分汽化来提供蒸汽。蒸汽重新返回塔中。塔底的残余物作为釜液或塔底产品被取出。达到塔底的气相在塔底冷凝器中被冷却并冷凝成液体。部分被冷凝的液体回流到塔中从而提供液体溢流。塔顶馏分的剩余物作为馏分或塔顶产品被取出。 This overall flow pattern in a distillation column provides countercurrent contacting of vapor and liquid stream on all the trays through the column Vapor

9、 and liquid phases on a given tray approach thermal pressure and composition equilibriums to an extent dependent the efficiency of the contacting tray 在蒸馏塔中的整个流动模式为气相和液相提供了一个在每一个塔盘逆流接触的机会。气相和液相在特定的塔盘上达到热量压力以及组成的平衡这在一定程度上取决于接触的塔板的效率。 The lighter(lower-boiling)components tend to concentrate in the vap

10、or phase,while the heavier(higher-boiling)components tend toward the liquid phase The result is vapor phase that becomes richer in light components as it passes up the column and a liquid phase that becomes richer in heavy components as it cascades downward. The overall separation achieved between t

11、he distillate and the bottoms depends primarily on the relative volatilities of the components, the number of contacting trays, and the ratio of the liquidphase flow rate to the vapor-phase flow rate. 低沸点的轻组分倾向于气相中富集而同时高沸点的重组分倾向于在液相中富集。这个结果是当它沿着塔向上移动的时候气相变得富含轻组分，而当液体沿着塔积极向下移动的时候液相变得富含重组分。要在塔顶产品和釜液之间

12、达到整个分离主要依赖于组分的相对挥发度，接触塔盘的数目和液相和气相流动的比例。 If the feed is introduced at one point along the column shell the column is divided into an upper section which is often called the rectifying section, and a lower section which is often referred to as the stripping section. These terms become rather indefinit

13、e in multiple-feed columns and columns from which a product sidestream is withdrawn somewhere along the column length in addition to the two end-product streams. 如果进料从塔壳的某一个点引入这个塔被分成一个向上部分，这个部分通常叫做精馏段，还有一个向下的部分，这个部分叫做提馏段。这些术语在多口进料塔中变得相当不确定。侧线产品沿着塔的某个地方被取中的塔会有两个最终产品馏分。 Equilibrium-Stage Concept Energ

14、y and masstransfer processes in an actual distillation column are much too complicated to be readily modeled in any direct way This difficulty is circumvented by the equilibriumstage model in which vapor and liquid streams leaving an equilibrium stage are in complete equilibrium with each other and

15、thermodynamic relations can be used to determine the temperature of and relate the concentrations in the equilibrium streams at a given pressure. A hypothetical column composed of equilibrium stages (instead of actual contact trays)is designed to accomplish the separation specified for the actual co

16、lumn The number of hypothetical equilibrium stages required IS then converted to a number of actual trays by means of tray efficiencies which describe the extent to which the performance of an actual contact tray duplicates the performance of an equilibrium stage 平衡级的概念 实际的蒸馏塔中的能量以及质量传递过程太复杂以至于不能从一种

17、方式直接做成模型。这个难题可以通过平衡级模型避免。在平衡级模式中气相和液相达到一个完全的平衡并且热力学关系可以被用于测量温度以及相关的浓度在某个特定压力下的平衡流中。由平衡级组成的一个特定的塔。代替了实际过程中的接触塔盘被设计用来完成实际塔的特定的分离。需要的假想得平衡级的数目通过塔盘效率的方法转化成一个实际塔盘的数目。塔盘效率描述了实际的接触塔盘的行为复制平衡级行为的程度。 Use of the equilibrium-stage concept separates the design of a distillation column into three major steps (i)T

18、hermodynamic data and methods needed to predict equilibriumphase compositions are assembled (ii)The number of equilibrium stages required to accomplish a specified separation or the separation that will be accomplished in a given number of equilibrium stages is calculated (iii)The number of equilibr

19、ium stages is converted to an equivalent number of actual contact trays or height of packing and the column diameter is determined 平衡级概念的使用 将蒸馏塔的设计分为三个主要的步骤 热力学数据和方法被收集，用来预测相平衡组分的。需要完成一个指定的分离或者在一个给定平衡级数目的情况下平衡级的数目需要被计算。平衡级的数被转化为等价的实际接触塔盘的数目或填料的高度。而且塔径被决定。 All separation operations require energy inp

20、ut in the form of heat or work. In the conventional distillation operation energy required to separate the species is added in the form of hear to the reboiler at the bottom of the column where the temperature is highest Also, heat is removed from a condenser at the top of the column, where the temp

21、erature is lowest. This frequently results in a large energy-input requirement and low overall thermodynamic efficiency. With recent dramatic increases in energy costs, complex distillation operations that offer higher thermodynamic efficiency and lower energy-input requirements are being explored.

22、所有的分离操作需要以热量或者做功的形式的能量的输入。在传统的蒸馏操作中用来分离物质的能量被以热量与形式注入到塔底的再沸器中，塔底的温度用最高的。热量从塔顶的冷凝器中被移走了在那里温度是最低的，这就导致了大量的能量的输入以及低的热力学效率。随着最高近能耗上的显著增加能够有更高的热力学效率以及较低能量输入的复杂的蒸馏技术正在被开发。 Related Separation Operations The simple and complex distillation operations just described all have two things in common :(i) both re

23、ctifying and stripping sections are provided so that a separation can be achieved between two components that are adjacent in volatility; and (ii) the separating agent (MSA) such as in liquid-liquid extraction. Sometimes, alternative single- or multiple-stage vapor-liquid separation operations, of t

24、he types shown in Fig. 3-2, may be more suitable than distillation for the specified task. 相关的分离操作工作 我们刚刚描述的简单的和复杂的蒸馏操作都有两个共同点。被提供的精馏段和提馏段都可以使挥发度相近的两个组分被分离。分离仅仅被能量的输入输出影响，不被加入任何的质量分离剂所影响 例如液液萃取。一些时候可选择的单级或者多级气液分离操作像在图3-2展示的类型也许比指定任务的蒸馏更适合。 Distillation Batch distillation, which is the process of sep

25、arating a specific quantity (the charge) of a liquid mixture into products, is used extensively in small production units that may have to serve for many mixtures. When there are N components in the feed, one batch column will suffice where N-1 simple continuous-distillation columns would be require

26、d间歇蒸馏.就是将一个特定量的液油混和物分离成产品,把它们广泛的用于实验室,还用于有许多类型混和物的产量少的生产单元.当进料有N种组分时,一个间歇蒸馏塔就可以满足,而却有N-1个连续蒸馏塔被需要. Many larger installations also feature a batch still Material to be separated may be high in solids content or it might contain tars or resins that would plug or foul a continuous unit Use of a batch u

27、nit can keep solids separated and permit convenient removal at the termination of the process许多大型设备也以间歇蒸馏塔为特点.待分离的物质可能固体含量高,或者有可能含有焦油或树脂,这些东西会阻塞或弄脏连续蒸馏.使用间歇蒸馏可以使固体.物质分离,并且在反应终止时能够更方便的转移. Simple Batch Distillation The simplest form of batch still consists of a heated vessel(pot or boiler), a condense

28、r ,and one or more receiving tanks. No trays or packing are provided. Feed is charged into the vessel and brought to boiling. Vapors are condensed and collected in a receiver. No reflux is returned. The rate of vaporization is sometimes controlled prevent bumping the charge and to avoid overloading

29、the condenser, but other controls are minimal. This processed further, or for similar noncritical separations.简单阿的歇蒸馏操作.最简单的间歇蒸馏塔仅由一个加热反应器,冷却器,一个或多个回收罐.不存在塔盘和填料.进料被装入一个釜并把它加热到沸腾.气相被冷却然后被收集到一个接收器中,没有回流.有些时候气化的速度会被控制来阻止进料暴沸并且要避免冷却器超载,但是其他的控制都是渺小的.这个过程常常被认为是瑞利蒸馏. The simple batch still provides only on

30、e theoretical plate of separation. Its use is usually restricted to preliminary work in which products will be held for additional at a later time, when most of the volatile component must be removed from the batch before it is processed further, or for similar noncritical separations. 简单的间歇蒸馏仅为分离提供

31、了一个理论的塔板.它的使用常被工程商限于初步的工作,产品被阻止,稍后用来额外的分离,在进行进一步反应之前绝大多数挥发性的物质必须被移除.或者是相似的非恒界分离. Batch Distillation with Rectification To obtain products with a narrow composition range, some means of splitting off a portion 0f the condensed vapor(distillate)as reflux and one or more receivers. Temperature of the d

32、istillate is controlled in order to return the reflux at or near the column temperature to permit a true indication of reflux quantity and to improve column operation The column may also operate at elevated pressure or vacuum in which case appropriate device must be included to obtain the desired pr

33、essure Equipment design methods for batch-still components except for the pot follow the same principles as those presented for continuous units hut the design should be checked for each mixture if several mixtures are to be processed It should also be checked at more than one point of a mixture sinc