英文翻译1
英文翻译1 -CAL-FENGHAI.-(YICAI)-Company One1
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 these 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 are 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 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column The remainder of the bottom liquid is withdrawn as bottoms or bottom product Vapor reaching the top of the column is cooled and condensed to liquid in the overhead condense Part of this liquid is returned to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 The remainder of the overhead stream is withdrawn as distillate, or overhead product.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 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 vapor 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 the distillate and the bottoms depends primarily on the relative volatilities of the components, the number of contacting trays, and the ratio of the liquid—phase 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 indefinite 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
Energy and mass—transfer processes in an actual distillation column are much too complicated to be readily modeled in any direct way This difficulty is circumvented by the equilibrium—stage model in which vapor and liquid streams leaving an equilibrium stage are in complete equilibrium with each other and 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 column 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)Thermodynamic data and methods needed to predict equilibrium—phase 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 equilibrium 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①热力学数据和方法被收集用来预测相平衡组分的。②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。③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 input 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 temperature 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.
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着增加
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。
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着增加
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。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 rectifying 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 the 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。①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。②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 separating 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 required
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 unit 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 condenser ,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 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 one 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 distillate 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 pressure 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 since composition in the column changes as distillation proceeds Pot design is based on batch size and required vaporization rate
含有精馏的间歇蒸馏如果想得到产品是有比较小的改变,一个精馏间歇蒸馏塔需要被使用,它的组成包括一个釜或者再沸器,精馏塔,冷凝器,还有一些方法把冷凝器中的一部分分离出来作为回流,还有一个或多个接收器.塔顶流出液的温度被控制是为了在或者接近塔温度的时候形成回流,允许一个真实的指示回流量,并且来提高塔的操作.这个塔可能也会在加压或者真空的条件下运作,在这种情况下一个合适的装置需要被安装来获得一个需要的压力.为间歇精馏组分装置设备设计方法除了釜的设计方法都要遵循和连续单元操作一样的规则,如果这些混和物需要被处理这个设计就需要对每一种混和物进行检验.他也将在混和物的多个点被检验,这是因为随着蒸馏的进行在塔里的组分会变化.釜的设计师建立在釜的尺寸和需要的汽化速率的基础之上.
In operation, a batch of liquid is charged to the pot and the system is first brought to steady stale under total reflux A portion of the overhead condensate is then continuously withdrawn in accordance with the established reflux policy Cuts are made by switching to alternate receivers at which time operating conditions may be altered The entire column operates as an enriching section As time proceeds, composition of the material being distilled becomes less rich in the more volatile 阿components and distillation of a cut is stopped when accentuated distillate attains the desired average composition 在操作过程中,一些液体被装入到釜中,整个系统首先在全回流情况下达到稳定的状态.通过切换的不同的接收器来将它们分开,.在这个时候操作条件可能被改变.整个塔作为一个富集部分操作,随着操作的进行,正在被蒸馏的材料的组成变得不再含有易挥发的组分,如果塔顶馏分的分离没有达到预期的目标就会被停止.
The progress of batch distillation call be controlled in several ways:歇他蒸馏操作可以通过以下方法提高.
(i) Constant reflux varying overhead composition Reflux is set at a predetermined value at which it is maintained for the run Since pot liquid composition is changing, instantaneous composition of the distillate also changes Distillation is continued until the distillate composition is at the desired value In the case of a binary, the overhead is then diverted to another receiver, and an intermediate cut is withdrawn until the remaining pot liquor meets the required specification. The intermediate cut is usually added to the next
batch For a multicomponent mixture two or more intermediate cuts may be taken between product cuts.
1.回流不变改变塔顶组成.回流比被设定在一个预定的值,整个系统在这个值下运行.由于釜液的组分发生改变,塔顶馏出液的组分立刻发生改变.蒸馏会一直连续进行直到塔顶馏出液的组分达到预定的值.在二元的情况下,塔顶馏分被直接传到另一个接收器,并且会有中间馏分被取出,直到剩余的釜液满足需要的特定的值.分出来的中间组分通常会被加到另一个间歇反应器.对于多组分的混和物,两种或者更多种的中间组分的分开在产品分开之间.
(ii) Constant overhead composition, varying reflux. If it is desired to maintain a constant overhead composition in the e of a binary, the amount of reflux returned to the column must be constantly increased through the run. As time proceeds, the pot is gradually depleted of the lighter component. Finally, a point is reached at which the reflux ratio has attained a very high value. The receivers are then changed, the reflux is reduced, and an intermediate cut is taken as before. This technique can also be extended to a multicomponent mixture 不变的塔顶组成,改变回流比.如果要求在二元的情况下维持一个不变的塔顶组成回到塔的回流量必须在整个运作中不断的减少。随着过程的进行釜里面的轻组分渐渐地耗尽。最后达到了回流比非常高的那个点。然后改变接收器回流比减小中间组分像以前那样被取出。这个技术也可以运用到多组分的混合物中。
(iii) Other control methods. A cycling procedure can be used to set the pattern for column operation. The unit operates at reflux until equilibrium is established. Distillate is then taken as total draw-off for a shout period of time, after which the column is again return to total-reflux operation. This cycle is repeated through the course of distillation. Another possibility is to optimize the reflux ratio in order to achieve the desired separation in a minimum of tie. Complex operations may involve withdrawal of side streams, provision for intercondensers, addition of feeds to trays, and periodic charge addition to the pot.
其他的控制方法在塔操作的过程中一个循环的步骤可以被设定成一种模式。这个单元在全回流的状态下运作直到平衡被建立。然后馏分在一小段时间内被全部取出在那之后塔又回到了全回流的状态。这个循环在蒸馏的过程中被重复进行。在最短的时间内为了达到一个期望的分离另一个可能性就是优化回流比。复杂的操作将会涉及到侧线取出中间冷凝器的防备向塔盘额外加料还有周期性的向釜内额外加料。