年處理量8萬噸苯——甲苯分離塔設計（全套CAD圖+說明書+開題報告+翻譯）

年處理量8萬噸苯——甲苯分離塔設計（全套CAD圖+說明書+開題報告+翻譯）,處理,萬噸苯,甲苯,分離,設計,全套,cad,說明書,仿單,開題,報告,講演,呈文,翻譯 英文翻譯 Chinese J．of Chem．Eng．，9(2)141—144(2001) Operation of a Batch Stripping Distillation Column xu Songlin(許松林) ，Jose Espinosab，Hector E．Salomoneb and Oscar A．Iribarrenb a National Engineering Research Center for Distillation Technology，Tianjin University, Tianjin 300072，China b Institute for Development and Design INGAR , Conicet，Santa Fe，Argentina Abstract A stripping batch distillation column is preferred when the amount of the light component in the feed is small and the products are to be recovered at high purity．The operation modes of a batch stripping are believed to be the same as those of a rectifier． However．the control system of a stripper is different． In this paper，we explore three different control methods with Hysys(Hyprotech Ltd．1997)for a batch stripper．The main difference is the control scheme for reboiler liquid level：(a)controlled by reflux flow；(b)controlled by reboiler heat duty；(c)controlled by bottom product flow． The main characteristics of operating a batch stripper with different control scheme are presented in this paper．Guidelines axe provided for the startup of a batch stripper，the effects of some control tuning parameters on the column performance are discussed． Key words batch stripper．control．Operation 1 INTRODUCTON Batch process is becoming more popular as chemical process industries move toward manufacturing fine and specialty chemicals，where flexibility is a key issue due to the frequent change of product demandBatch distillation columns are inherently flexible，as a single column call separate many different components from a multicomponent feed．Thus the use of batch distillation is becoming more important for the seperation and purification of high—value chemicalsin many chemical ,food，and pharmaceutical industries．Traditionally the most popular kind of batch distillation column is the so-caled rectilying column．which has a large reboiler，to which al the feed is charged．a(chǎn)n different products are removed from the top． There are three ways to operate a rectifying column[2]．They are：(1)constant reflux and variable distillate composition，(2)variable reflux an d constant distillate composition of key component，(3)optimal reflux policy which trades of(1)and(2)and is based on the most profitable operation． Batch stripping column is opposed to a batch rectifier． It has its storage vessel at the top and the products leave the column at the bottom ． A stripping batch distilation column is preferred when the amount of the light component in the feed is small and the products are to be recovered at high purity[4,5]． The operation modes of a batch stripping are believed to be the same as those of a rectifier． However．the control system of a stripper is different．In this paper，we explore three different control methods with Hysys(Hyprotech Ltd．1997)for a batch stripper．The control schemes are shown in Fig．1． The main difference is the control scheme for reboiler liquid level：(a)controlled by reflux flow，(b)controlled by reboiler heat duty，(c)controled by bottom product flow ．The main characterics of operating a batch stripper with different control scheme are presented in this paper．Guidlines are provided for the startup and the effect of so e control turning parameters on the column performance are discussed. 2 EXPERIMENTAL APPARTUS FOR THE SIMULATIONS The experimental apparatus in the simulations is the same for the three control schemes．The stripping column has a reboiler，a condenser and 15 trays．The volumes of the reboiler and the condenser are 2m3 and 5m3，respectively．The diameter of the column is 0.5 m．The feed is the mixture of methanol(0.05)and ethanol (0．95)(mole fraction)．The liquid percent level set point for the reboiler is 50％ and the mixture takes 80％ of the whole volume of the condenser．At the beginning，the trays are dry startup，but the reboiler is charged with the same mixture to the liquid level set point．The specification of bottom product ethanol is 0．999．All the simulated experimental procedures are that the stripper is started up till the specification of the heavy key composition is reached，then the bottom product valve is opened so that the product leavesthe column，the product valve is shut down when the product composition declines to the specification． 3 RESULTS AND DISCUSSION 3．1 Control reboiler Hquid level by reflux flow In this control scheme【Fig．1(a)】，the reboiler liquid percent level is controlled autom atically by reflux flow，the reboiler heat input and bottom product flow are controled manualy． At the beginning，the reboiler heat in put is set fixed．The reboiler liquid level declines as the light com ponent is vaporized．Which will cause reflux flow down the reboiler automatically．The control of the reboiler liquid level is reversible．So when the reboiler liquid level is higher，there wil be less reflux flow an d vice versa. When the composition of heavy key component gets to its specification，the bottom product flow valve is opened；once it declines to the specification，the bottom product flow valve is shut down manualy．In this case，when ethan ol corn -position reaches 0．999，the bottom product flow valve is opened ，when ethan l is less than 0．999 the bottom product flow valve is shut down． The dynamic process of this operation mode is shown in Fig．2．There is a time lag between the reboiler liquid level an d reflux flow ，especially when the number of stages is large．In order to get a stable reboiler liquid level control during the whole operation，two aspects should be considered carefully．0ne is to use an appropriate reflux valve． If the reflux valve is oversized，the reboiler liquid level controller wil get more reflux flow to the reboiler than the set point when the liquid level declines． Then the reflux flow valve will be closed． This makes the reboiler liquid level fluctuate frequently．One case is shown in Fig．3．In this situation the heavy key component composition in the bottom is unstable． The other aspect is that the tuning parameter of the reboiler liquid level should be chosen appropriately when a proportional only bottom level controler is employed．The proportional gain of the controler should be between 4．0and 8．0．If is too small，it is difficult to get a stable reboiler liquid level contro1．Fig．4 shows the relation between reboiler liquid percent level and for the same reboiler duty．From Fig．4．it is obvious that if is less than 4．0 the liqui d percent level in the reboiler is far away from the set point level 50％．If is between 4．0 and 8．0，the liquid level in the reboiler is near the set point． 3．2 Control reboiler liquid level by reboiler heat input In this control scheme [Fig．1(b)】，the reboiler liquid level is controlled by reboiler duty automatically,reflux and bottom products flow are controlled manually．At the beginning，the reflux flow valve is opened to a fixed value．Reboiler liquid level increases，which will cause heat input to the reboiler．The action of the reboiler liquid level controler is direct，which means that the higher the reboiler liquid level，the more the heat input to the reboiler and vice versa．When the com position of the heavy key component in the reboiler gets to its specification．the bottom product flow valve is opened manuly． When the heavy key component com position decreases to 0．999，the valves for bottom product an d reflux flow are shut down manually．Fig．5 shows the dynamic process of this operation mode． It is obvious that the boil up mass flow and the liquid levels of condenser and reboiler are fluxed at the startup of the operation．This is due to the dynamic responsiveness of reboiler heat input to the liquid level controller． 3．3 Control reboiler Hquid level by bottom product flow The reboiler liquid level is controled by bottom product flow in this control scheme[Fig．1(c)】．This scheme is similar to the third control mode for a rectifier．in which the reboil ratio is variable． In order to get the bottom product specification，a total reboil process should be established at the beginning of the operation．The action of the reboiler liquid level controller is direct，which means that the higher the liquid level，the more the bottom product flow and vice versa． Figure 6(b)shows that at the startup of this operation，the liquid levels in both reboiler and condenser are oscillated，since it is difficult to meet the requirement for the total reboil at the beginning of the operation，for the reflux flow and reboiler heat input are operated manually． 4 CONCLUSION The dynamic simulation with Hysys for the operation of a batch stripping distillation column indicates the main characterics of this kind of column，in which three different control schemes are employed．In the first scheme，reboil ratio is constant with variable bottom product com position；in the second scheme，reboil ratio is variable and the heavy key component composition in the bottom product is nearly constant，and the third is an optim al operation which could obtain more profit． Among these three control modes，the third is the most difficult to operate，since both controllers for reflux flow and reboiler heat input are operated manually．This work demonstrates the operation of a batch stripping column，provides some practical guidlines for the startup and operation of the column，shows how the column can be run under different operating modes，and clarifies the effect of some key control tuning on the column performance． However，this work is a dynamic simulation． The practical operation of a batch stripping distillation column still needs to be investigated in detail． REFERENCES 1 Salomone，H．E．，Chiotti，O．J．，Iribarren，O．A．，“Short．cut design procedure for batch distillation”，Ind．Eng． Chen]． Res．，36 (1)，13 一136(1997)． 2 Sundaram，S．，Evans，L．B．，“Shortcut procedure for simulating batch distillation operations”，Ind． EI ． en]． Res．，32(3)，511— 518(1993)． 3 Yang，zh．C．，Yu，G．C．(K．T． )，Mo，zh．M．，e￡a／．， t “Study on optimal strategies and microcomputer control of batch distillation(Ⅱ)Batch distillation column and its microcomputer control”，J．(Chem．Ind．Eng．(China，40(3)， 28 一286(1989)．(in Chinese) 4 Lotter， S． P．， Diwekar， U． M ．， “Shortcut models and feas ibility consideration for emerging batch distillation columns”，Ind．Eng．Chem．Res．，36(4)，760—767(1997)． 5 Scrensen，E．，Skogestad，S．，“Comparison of regular and inverted batch distillation”，Chem． Eng． Sci．，51 (22)， 4949．一4962 of 1996)． 分批沖孔模板精餾塔的操控 許松林，Jose Espinosab，Hector E．Salomoneb，Oscar A．Iribarrenb a 中國 ，天津，300072，天津大學，國家精餾工程技術(shù)研究中心 b 阿根廷，桑塔費，康尼賽特，INGAR發(fā)展與設計學院 摘要 當大量的輕的成分在流量中很少和高純度產(chǎn)品回收時分批沖孔模板精餾很重要，批量精餾塔的操控與鎮(zhèn)流器的作用是相同的。然而，沖孔模板的控制系統(tǒng)是不同的。在這篇論文里，我們探索沖孔模板三種不同的控制方法：Hysys(Hyprotech Ltd．1997)，最主要的不同之處是重沸器液相控制圖；（a）以回流量控制;（b)以重沸器熱負載控制；（c）以底部產(chǎn)品流量控制。在此論文里闡述分批沖孔模板精餾塔的操控最主要的特征是不同的控制流程圖，分批沖孔模板控制開始時提供了準則，將要討論一些柱面上的控制調(diào)諧參數(shù)。 圖1分批沖孔模板的控制流程 1-塔體；2-重沸器；3-冷卻機；4-整流器；LC-液面控制器；PC-壓力控制器 關(guān)鍵詞 分批沖孔模板 控制 操作 1 簡介 隨著化工工廠向著大規(guī)模精細生產(chǎn)和專業(yè)化工產(chǎn)品方向發(fā)展，批量生產(chǎn)變得比較流行，這樣簡易方法對于產(chǎn)品需求的頻繁變化起關(guān)鍵作用。批量精餾塔是固有簡易特性的，正如一個柱可以由一個多組分供給分成許多不同的組份，這樣批量精餾的用途對于一些化學，食品和藥物公司的高價值的化工產(chǎn)品的分離和提純變得越來越重要。 傳統(tǒng)的，最流行的批量精餾方法被稱為整流柱，它有一個大的重沸器，對它所有的供給都是變化的，并且不同產(chǎn)品從頂部分離開。操作整流塔有三種方法：（1）回流量為恒量并且精餾組份為變量，（2）回流量為變量并且精餾的主要組份為恒量，（3）最佳回流量協(xié)調(diào)了（1）和（2）并且建立在最經(jīng)濟的試驗。 批量沖孔模板與批量整流是相反的。在它的頂端有它的儲存容器并且產(chǎn)品從塔的底部分離出。當大量的輕的成分在流量中很少和高純度產(chǎn)品回收時分批沖孔模板精餾很重要。 批量精餾塔的操控與鎮(zhèn)流器的作用是相同的。然而，沖孔模板的控制系統(tǒng)是不同的。在論文中，我們探索Hysys(Hyprotech Ltd．1997)的批量沖孔模板三種不同的控制方法，圖表1給出了控制圖。最主要的不同之處是重沸器液相控制圖；（a）以回流量控制;（b)以重沸器熱負載控制；（c）以底部產(chǎn)品流量控制。 （a）底部產(chǎn)品的組分 （b）塔體中的溫度 （c）質(zhì)量流量 （d）頂部和底部的流量 在此論文里闡述分批沖孔模板精餾塔的操控最主要的特征是不同的控制流程圖，分批沖孔模板控制開始時提供了準則，將要討論一些柱面上的控制調(diào)諧參數(shù)。 2 模擬實驗儀器 模擬實驗儀器和三種控制圖是相同的，脫模塔有個重沸器和2 m 3和5 m 3的冷凝器，他的直徑是0.5m.供給成分是甲醇（0.05）和乙醇（0.95）（餾分）的混合物。占冷凝器容量的80%，開始時，板是干啟動的，但是重沸器是由相同的混合液的液相點控制的。底部產(chǎn)品乙醇的規(guī)范是0.999.所有的仿真實驗程序是從沖模開始直到關(guān)鍵的組份達到規(guī)范，然后底部產(chǎn)品閥開啟使產(chǎn)品分離，當產(chǎn)品組份低于規(guī)范時產(chǎn)品閥關(guān)閉。 3 結(jié)果和討論 3.1 通過回流量控制重沸器液面 在控制圖中【圖表1（a）】,重沸器液相百分比是由回流量自動控制的，重沸器的熱輸出和底部產(chǎn)品的流量是手動控制的。開始時，重沸器的熱輸出是設定的，重沸器的液面隨著輕成分的蒸發(fā)而降低，這將導致回流自動地流向重沸器。重沸器的液面控制是可逆的，所以當重沸器的液面較高時，回流量將較少。當關(guān)鍵組份是成分達到其規(guī)范時，底部的閥開啟，一旦它低于規(guī)范，底部產(chǎn)品流出閥就手動關(guān)閉，這樣的話，當乙醇成分達到0.999，底部產(chǎn)品流出閥開啟，當乙醇成分低于0.999，底部產(chǎn)品流出閥關(guān)閉。 圖表3重沸器液面的波動 圖表2表示了此操作模式的動態(tài)過程。在重沸器液面和回流之間存在時間滯后，尤其是當階段數(shù)目很大時。為了在整個控制中達到一個穩(wěn)定的重沸器的液面。必須仔細考慮兩個方面。如果回流閥過大，當液面降低時，重沸器的液面控制器將從重沸器得到比預設多的回流量。然后回流閥將會關(guān)閉。這使重沸器液面頻繁波動。圖表3展現(xiàn)出了一種情況，在這種情況底部關(guān)鍵成分的組成是不穩(wěn)定的，另一方面是重沸器的液相參數(shù)應該合理選擇盡當?shù)撞靠刂破鞯谋壤囉脮r?？刂破鞯谋壤鲆鍷p應該在4.0和8.0之間。如果Kp值太小，就很難使重沸器液面控制達到穩(wěn)定。圖表4展示了重沸器液相百分比與相同的重沸器的Kp值之間的關(guān)系。從圖表4中，很明顯的看出如果Kp值低于4.0時重沸器的液相百分比將低于預設值的50%。如果Kp值在4.0和8.0之間，重沸器的液面會處在預設值的附近。 圖表4 Kp值對重沸器液面的影響 3.2 通過重沸器的熱輸出控制重沸器的液面 在控制圖中【圖表1（b）】中，重沸器的液面是由重沸器的負載自動控制的，回流和底部產(chǎn)品的流出是手動控制的。開始時，回流閥須有一個特定值。重沸器的液面增加將導致對重沸器的熱輸入。重沸器的液面控制器的功能是直接的，這意味著重沸器液面越高，重沸器的熱輸入越多。當關(guān)鍵組份是成分達到其規(guī)范時，底部的產(chǎn)品流出閥手動關(guān)閉。當關(guān)鍵組份是成分降至0.999時，底部產(chǎn)品流出閥和回流閥也手動關(guān)閉。圖表5表示了此操作模式的動態(tài)過程。很明顯的看出煮沸的大量流量和冷凝器的液面以及重沸器都回流至控制初期。這是由于重沸器的動態(tài)響應度的熱輸入對控制器的液面的影響。 （b）溫度 （c）質(zhì)量流量 （d）流量 （e）重沸器熱負載 3.3通過底部產(chǎn)品流量控制重沸器液面 通過底部產(chǎn)品流量控制重沸器液面的控制圖表示在[圖表1（c）]中。這個圖與整流器的第三種控制模式，其中重沸比例是可變的。為了使底部產(chǎn)品規(guī)范，全部的重沸過程應建立在控制的初始值。重沸器的液面控制器的功能是直接的，這意味著重沸器液面越高，重沸器的熱輸入越多。 （a）產(chǎn)品組成 （b）流量 （c）質(zhì)量流量 （d）溫度 圖表6（b）表示了控制過程的初始階段，在重沸器和冷凝器中的液面振動，因為很難達到整個重沸開始時的需求，回流量和重沸器的熱輸入都是手動控制的。 4 結(jié)論 Hysys的動態(tài)模擬分批沖孔模板精餾塔的操控實驗表明這種塔的主要特性，其中是實施了三種不同的控制流程。在第一種流程中，回流率是隨底部產(chǎn)品的成分對應變化的；在第二種流程中回流率是變化的，底部產(chǎn)品的成分是接近不變的，而第三種流程會更經(jīng)濟一些的。在這三種控制模式中，第三種最難控制，因為回流量和重沸器的熱輸入都是手動控制的。 這項工作證明了分批沖孔模板的實驗，為塔體的控制和開始提供了一些實際的流程表明了塔體能夠在不同的操作模式下運作，并且闡述了一些關(guān)鍵的控制參數(shù)。然而，這項工作只是一個動態(tài)模擬。分批沖孔模板精餾塔的操控仍然需要詳細的調(diào)查。 參考文獻 1 Salomone，H．E．，Chiotti，O．J．，Iribarren，O．A．，“Short．cut design procedure for batch distillation”，Ind．Eng． Chen]． Res．，36 (1)，13 一136(1997)． 2 Sundaram，S．，Evans，L．B．，“Shortcut procedure for simulating batch distillation operations”，Ind． EI ． en]． Res．，32(3)，511— 518(1993)． 3 Yang，zh．C．，Yu，G．C．(K．T． )，Mo，zh．M．，e￡a／．， t “Study on optimal strategies and microcomputer control of batch distillation(Ⅱ)Batch distillation column and its microcomputer control”，J．(Chem．Ind．Eng．(China，40(3)， 28 一286(1989)．(in Chinese) ’ 4 Lotter， S． P．， Diwekar， U． M ．， “Shortcut models and feas ibility consideration for emerging batch distillation columns”，Ind．Eng．Chem．Res．，36(4)，760—767(1997)． 5 Scrensen，E．，Skogestad，S．，“Comparison of regular and inverted batch distillation”，Chem． Eng． Sci．，51 (22)， 4949．一4962 of 1996)．