赵天奇外文翻译

1、吉林化工学院外 文 翻 译精馏塔的设计性 质: 毕业设计 毕业论文教 学 院： 机电工程学院系 别：过程装备系学生学号：12420332学生姓名：赵天奇专业班级：过控1203指导教师：高艳职 称：副教授起止日期：2016.2.292016.6.17吉 林 化 工 学 院Jilin Institute of Chemical Technology吉林化工学院本科毕业设计（论文）外文翻译精馏塔的设计摘要：本文综述了精馏塔设备的类型及特点，工原理及在化工行业的生产运用优点和不足等内容，对目前国内外精馏塔的现状及发展趋势做了介绍。关键词：模拟蒸馏；化学处理；蒸馏控制；稳态建模；气液传质设备主要分为板式

2、塔和填料塔两大类。精馏操作既可采用板式塔，也可采用填料塔。板式塔在工业上最早使用的是泡罩塔、筛板塔，其后，特别是在本世纪五十年代以后，随着石油、化学工业生产的迅速发展，相继出现了大批新型塔板，如S型板、浮阀塔板、多降液管筛板、舌形塔板、穿流式波纹塔板、浮动喷射塔板及角钢塔板等。目前从国内外实际使用情况看，主要的塔板类型为筛板塔、浮阀塔及泡罩塔，而前者使用尤为广泛。在化工、炼油、医药、食品及环境保护等工业部门，塔设备是一种重要的单元操作设备。它的应用面广、量大。据统计，塔设备无论其投资费还是所有消耗的钢材重量，在整个过程装备中所占的比例都相当高。精馏是分离液体混合物最常用一种作，在化工、炼油等工

3、业中应用很广。它通过汽、液两相的直接接触，利用组分挥发度的不同，使易挥发组分由液相向汽相传递，难挥发的由汽相向液相传递，是汽、液两相之间的传质过程。本设计是笨-氯苯连续分离精馏塔，而氯苯是一种重要的基本有机合成原料，用作染料、医药、农药、有机合成中间体。用于制造苯酚、硝基氯苯、二硝基氯苯、苯胺、硝基酚及杀虫剂滴滴涕等，也用作乙基纤维素和许多树脂的溶剂。氯苯的下游产品中，硝基氯化苯是氯苯的主要消费用户，对硝基氯化苯是重要的染料、农药、医药的中间体。以对硝基氯化苯为原料可以生产对硝基苯酚、对硝基苯胺、对氨基苯酚、对苯二胺、对氨基苯甲醚和对氨基苯乙醚等一系列有机化工产品。但由于用苯氯化法制氯苯后，苯

4、和氯苯互溶，因此需设计一个精馏塔用来分离易挥发的苯和不易挥发的氯苯。 首先，苯和氯苯的原料在原料预热器中加热到泡点温度，然后，原料从进料口进入到精馏塔中。因为被加热到泡点，混合物中既有气相混合物，又有液相混合物，这时候原料混合物就分开了，气相混合物在精馏塔中上升，而液相混合物在精馏塔中下降。气相混合物上升到塔顶上方的冷凝器中，这些气相混合物被降温到泡点，其中的液态部分进入到塔顶产品冷却器中，停留一定的时间然后进入苯的储罐，而其中的气态部分重新回到精馏塔中，这个过程就叫做回流。液相混合物就从塔底一部分进入到塔底产品冷却器中。一部分进入再沸器，在再沸器中被加热到泡点温度重新回到精馏塔。塔里的混合物

5、不断重复前面所说的过程，而进料口不断有新鲜原料的加入。最终，完成苯与氯苯的分离。填料塔属于微分接触型的气液传质设备。塔内以填料作为气液接触和传质的基本构件。液体在填料表面呈膜状自上而下流动，气体呈连续相自下而上与液体作逆流流动，并进行气液两相间的传质和传热。两相的组分浓度或温度沿塔高呈连续变化。板式塔是一种逐级接触的气液传质设备。塔内以塔板作为基本构件，气体自塔底向上以鼓泡活喷射的形式穿过塔板上的液层，使气-液相密切接触而进行传质与传热，两相的组分浓度呈阶梯式变化。综合考虑板式塔由于比填料塔性能稳定、效率高、安装检修方便及造价低等优点，本设计选用板式塔。塔板是板式塔的主要构件，分为错流式塔板和

6、逆流式塔板两类，工业应用以错流式塔板为主，常用的错流式塔板主要有泡罩塔、筛板塔、浮阀塔等。筛板塔在相对气液相负荷、效率、可靠性以及价格方面都较其他两种塔优，因此本设计选用筛板塔，其特点如下：结构简单、制造维修方便；生产能力大，比浮阀塔还高；塔板压力降较低，适宜于真空蒸馏；塔板效率较高，但比浮阀塔稍低；合理设计的筛板塔可是具有较高的操作弹性，仅稍低与泡罩塔；小孔径筛板易堵塞，故不宜处理脏的、粘性大的和带有固体粒子的料液。本设计的题目是苯-氯苯分离精馏塔设计，即需设计一个精馏塔用来分离易挥发的苯和不易挥发的氯苯，采用连续操作方式，具体工艺参数如下：处理量：12000吨/年料液组成（含氯苯）：34产

7、品组成（氯苯纯度）：99塔顶产品组成（含氯苯）：1.5操作压力：塔顶压强4KPa(表压) 进料热状况和回流比自选塔底加热蒸气压力：0.5MPa（表压) 单板压降：0.7KPa 地震裂度：7度土质情况：第二类场地土当地气压=100kPa 设备年工作时间：300天（每天24小时连续运行）水电供给：水源充足，供电正常对于16MnR钢板负偏差1c=0，因而名义厚度6nmm。但对于低合金钢制容器，规定不包括腐蚀裕量的最小厚度应不小于3mm，若加上5mm的腐蚀裕量，名义厚度至少取8mm。 由于封头的椭球部分经线曲率变化平滑连续，故应力分布比较均匀，且椭圆形封头深度较半球形封头小得多，易于冲压成型，是目前中

8、、低压容器中应用较多的封头。因此本设计选用椭圆形封头。 塔的手孔是操作人员对塔进行检验及维修用的。本塔设计中手孔选择DN250的4带颈对焊法兰手孔。由于工艺操作需要有各种接管，在本塔的设计中接管的尺寸分别是DN32，DN50，DN65，DN80，DN125，所有接管均不用补强。参考文献：1Bcoli,Luyben Shunta,蒸馏塔控制设计2Thirston·c·W“蒸馏塔控制的计算机辅助设计”,碳氢化合物处理3Tolliver.And McCune“蒸馏塔控制设计基于稳态仿真”,ISA事务卷4Roat s D。More c.F。,J.J。一

9、个稳态蒸馏塔控制系统灵敏度分析技术”5Skogestad S.动力学和控制”,蒸馏塔一个关键的调查”,预印本IFAC研讨会,DYCORD ,大学公园,医学博士,美国6Luyben w·L“稳态蒸馏塔的节能方面控制设计”,I&E.C,Fundam,14卷,4号,1975年。7Chine I-L And Fruehauf P.S。“考虑IMC优化来改善控制器性能”,C.E.P.卷。86年,1990年10月10号。8Shunta j.p. And Luyben w.L。“动态效果的温度控制在蒸馏塔盘置”,AICHE J,17卷,1971年1月1号ABS

10、TRACTSteady state models continue to be powerful and efficient tools for designing control systems  for distillation columns.  This paper presents a control design procedure a

11、nd an example  applicati n of this technique to an actual column.KEYWORDSComputer Aided Engineering, Simulated Distillation, Chemical Processing, Distillation Control, Steady State Modeling 

12、  INTRODUCTION ：Steady state process models have long been used to assist the control engineer in designing control strategies for distillation columns. However, with the large number of industrial columns still operating in manual or with ineffectual controls, there remains a need for sou

13、nd distillation column control design techniques. We believe that Tolliver and McCune (1978) have made the greatest contribution to the development of this type of design procedure. Two other very good papers on this subject are by Thurston (1981) and Roat, et al (1988). While our procedure is an ex

14、tension of that proposed by Tolliver and McCune, we have improved the procedure in the following ways· We advocate that mass flows be used in models versus the previous standard of molar flows. We have determined independently that use of molar flows can lead to incorrect results. A recent revi

15、ew article on distillation column control by Skogestad (1992) confirms these findings. · We also advocate that the actual control structure be enforced when using the steady state simulation to identify a temperature sensor location for composition control. This is accomplished by a careful cho

16、ice of independent variables when defining the model solution conditions. Tolliver and McCune advocate varying only molar distillate flow regardless of the proposed control structure. This too can lead to incorrect results. · We show that this technique can be used for multicomponent columns to

17、 quantify the incremental benefit of composition control using on-line analyzers versus temperature control.This paper deals exclusively with the design of single point composition controls. The vast majority of columns have one sided composition specifications; those in which a single point composi

18、tion control scheme can keep both top and bottom product compositions at or below limits for a wide range of disturbances. This does not have to be accepted on faith because the design procedure explicitly tests this hypothesis. The predominance of one sided specifications leaves the main incentive

19、for dual point control schemes to be energy savings. In most cases, the energy savings is small and does not justify the added difficulty of implementing and maintaining dual point control. Luyben (1975) presents the potential energy savings for many different types of separations. Additionally, dua

20、l point schemes often have significantly longer recoveries from upsets due to interactions between the control loops. We believe it is appropriate to contrast steady state and dynamic models as control design tools. While both tools have a place, we have found that using steady state models coupled

21、with experience and a general knowledge of distillation column dynamics is adequate for many problems and can be more efficient than using dynamic models. For a good development on the rationale behind using steady state models refer to the chapters on Quasi-Static Analysis in Rademaker, et al (1975

22、). One obvious limitation of steady state modeling is that it tells us nothing about the dynamic response, making it difficult to compare the dynamic disturbance rejection capability of alternative control schemes. When we encounter a difficult and important problem we invest the extra engineering t

23、ime to develop a dynamic model. The ideal design tool would be one that has both steady state and dynamic capabilities. This tool would provide the efficiency of steady-state analysis, but would also have the added benefit of comparing the disturbance rejection capabilities of different schemes with

24、 the dynamic model. The combined tool would allow the designer to perform both tasks without requiring an investment in time to develop two different models. A new product soon to be released by Hyprotech, Ltd. will combine steady state and dynamic modeling in one such package. Our design procedure

25、can be best thought of as general approach rather than a single detailed procedure that covers all cases. The procedure must be adapted to each problem because there are many different types of distillation and almost every industrial problem usually has some unique requirement.We have applied this

26、general procedure to many different types of specialized columns including homogeneous and heterogeneous azeotropes, extractive distillation, strippers and absorbers and multicomponent columns. We have also used this procedure for many different column configurations including columns with either li

27、quid or vapor side draws, columns with partial condensers and with both packed and tray columns.Because we often encounter columns with multiple components in the feed, a little more should be said about these&

28、#160;cases.  In multicomponent columns, unlike binary columns, fixing temperature and pressure does not fix composition.  In spite of this limitation, temperature control can 

29、still be used to meet many composition specifications.  Often this results in larger yield losses or higher energy consumptions than if an on-line analyzer was available 

30、for control. This is where steady state models can be very helpful to us because we can use them to quantify the incremental benefit of on-line analyzers versus 

31、;temperature control.  In one case, we used this technique to document the yield improvement to be gained from the addition of an on-line analyzer.  The savings 

32、;was over two hundred thousand dollars a year.DESIGN PROCEDURE ：We have extended the design procedure reported by Tolliver and McCune (1978). The design procedure is composed of the following steps: Step 1 Develop design basis 

33、60;Step 2 Select a candidate control scheme.  Step 3 "Open loop" test using model to find a candidate temperature sensor location.  Step 4 "Closed loop&quo

34、t; test candidate control scheme for feed rate and feed composition DisturbancesStep 1    Develop Design Basis - Like any design effort, the ideal first step is

35、 to completely define the design basis providing all the information needed to select the best design alternative.  This basis should be a contract between the clien

36、t and the designer.  The accuracy of the basis is mainly the client's responsibility.  The components of the design basis are summarized in Table 1.  The

37、60;first piece is the product composition specifications for the top and bottom of the column.  We need to know if the specifications are one or two sided. 

38、0;A one sided specification means that we need to meet or exceed a product composition specification.  A two sided specification means that we need to keep a co

39、mposition within a certain range.  For example, a two sided specification would require that the product composition stay within 90-110 ppm.  A one sided specification

40、60;is much more common. We have encountered only one column that has a two sided specification.  It is also important to know the reasons for the specifications.

41、0; Occasionally, some specifications are picked arbitrarily simply to have a sizing basis for a column and we find that tight control is not critical.  The design

42、60;basis also includes the economic considerations and the disturbances to the column.  As you will see, a good definition of the range of feed rate and feed co

43、mposition disturbances is required to complete the design procedure.  The next element of the design basis is the constraints.  We need to know which of the str

44、eams will be the demand stream.  If the design is a retrofit of an existing column, we need to know how the column is currently controlled and why.  T

45、his is important because if we see a need to change the control strategy, we need to make sure that the change will not upset the overall control strategy 

46、for the process.  The reasons for a given control strategy can be very subtle, particularly if there are recycle streams in the process.    Other constraints

47、60;include those imposed by the upstream and downstream equipment and recycle streams involving the products from the distillation column.  If the process has recycle streams,

48、 the approach is to draw a box around the process so that the recycle stream remains inside the box and then analyze that part of the process as a sys

49、tem.  Although the design procedure for recycle systems is not covered here, it is just an extension of this procedure.  The last part of the design basis 

50、is simply the base case that was originally used to size the column.Step 2 Select a Candidate Control Scheme - The second step of the design procedure is to select a candidate control strategy. In a 5x5 system, like simple binary distillati

51、on, there are 120 possible single input, single output control combinations. And this is without considering combinations of process outputs as variables. Fortunately, in most situations, only a few combinations are left after everything (constraints, economics, etc.) is considered. The control stra

52、tegy selection procedure is as follows. It is very similar to the procedure outlined by Buckley, et. al. (1985). we need to determine how the column base and reflux drum level will be controlled. This is done by comparing the relative magnitudes of the reflux flow versus the distillate flow and the

53、boilup flow versus the bottoms flow. If there is a 10 to 1 or greater difference, then the level needs to be controlled by manipulating the larger stream. One common situation where this consideration is important, is in a tar still. In a tar still, we are usually trying to remove a small quantity o

54、f a high boiling material. The boilup can be 100 times that of the bottoms stream.The bottoms stream is too small to compensate for common disturbances, therefor, the base level must be controlled by manipulating the steam flow, rather than the very small bottoms stream. In most cases, we use a colu

55、mn tray temperature to infer composition. We use temperatures because the measurement is inexpensive, highly reliable, repeatable, has a high degree of resolution, is continuous, and is generally an excellent indicator of column product compositions. we need to determine how the column base and refl

56、ux drum level will be controlled. This is done by comparing the relative magnitudes of the reflux flow versus the distillate flow and the boilup flow versus the bottoms flow. If there is a 10 to 1 or greater difference, then the level needs to be controlled by manipulating the larger stream. One com

57、mon situation where this consideration is important, is in a tar still. In a tar still, we are usually trying to remove a small quantity of a high boiling material. The boilup can be 100 times that of the bottoms stream. The bottoms stream is too small to compensate for common disturbances, therefor

58、, the base level must be controlled by manipulating the steam flow, rather than the very small bottoms stream. In most cases, we use a column tray temperature to infer composition. We use temperatures because the measurement is inexpensive, highly reliable, repeatable, has a high degree of resolutio

59、n, is continuous, and is generally an excellent indicator of column product compositions. In general we prefer to measure temperature for control purposes nearer to the end of the column with the most 

60、;important purity specification.  Additionally, the temperature at the sensor location ought to be reasonably sensitive to changes in the manipulative variable, and should vary

61、0;linearly with increasing and decreasing values of the manipulative variable.  We have found that in some cases we can control tray temperature to within a half of&

62、#160;a degree centigrade.  Based on this performance, we consider a plus or minus one degree change at a given location to be sufficient for temperature control. 

63、60;In the literature, there are many different techniques proposed on how to locate a temperature sensor.  One of the many techniques is reported by Shunta and Luybe

64、n (1975).  This is one area where we feel more research work is needed to find a single reliable method.  We have found that the equal temperature change&#

65、160;rule used in the above example does not always determine the best location.  This is one area where steady state techniques are limited.  Although it is not

66、 fully tested, we believe that a technique that uses dynamic modeling may be superior.  The technique would involve plotting temperature profiles at fixed time intervals&

67、#160;for step increases and decreases in the temperature control manipulative variable.  To do this efficiently, a modeling tool which has both dynamic and steady state m

68、odeling will be required.Step 3    "Open Loop" Test Using Model To Find Candidate Temperature Sensor Location -     The third step of the design procedure involves what we have termed "open loop" testing.  The purpose of the "open loop" testing is to use the steady state model to i