年产7万吨丙烯腈项目合成工段设计

喜欢就充值下载吧。。资源目录里展示的文件全都有，，请放心下载，，有疑问咨询QQ:1064457796或者1304139763 ==================== 喜欢就充值下载吧。。资源目录里展示的文件全都有，，请放心下载，，有疑问咨询QQ:1064457796或者1304139763 ==================== 开题报告 题 目： 年产7万吨丙烯腈项目初步设计 －合成工段工艺设计 专 业： 姓 名： 学 号： 指导教师： 年 月 开 题 报 告 一、课题的目的与意义 丙烯腈是三大合成材料—合成纤维、合成橡胶、合成塑料的基础原料[1]，这使得丙烯腈的地位逐年提高，所以丙烯腈生产及其深加工日益受到人们的重视。丙烯腈的生产方式有很多种，丙烯直接氨氧化工艺、丙烷直接氨氧化工艺和丙烷脱氢后再进行丙烯氨氧化工艺等工艺方法。其中利用丙烯氨氧化生产丙烯腈是丙烯腈生产的主要方式之一[2-3]。这种方法设备简单，原料易得。反应所用到的丙烯是重要的石油化工基础原料，因此研究丙烯腈生产过程，提高丙烯腈产品质量，降低丙烯腈原料消耗就显得十分重要了。 我国丙烯腈的总需求量也将以年均10.8%的速率递增。中国丙烯腈市场新建和扩建项目较多，产能增长将维持较高水平，但是这还是无法弥补国内丙烯腈的需求缺口[4-6]。预计到2017年，我国国内生产的丙烯腈还是无法满足国内需求。即我国现有的丙烯腈生产能力还远不能满足国内的需求，仍需大量进口。因此 , 加大对丙烯腈生产工艺技术和催化剂体系的研究开发力度, 不断提升我国丙烯腈生产的技术水平 ,是解决我国丙烯腈供需的平衡是关键之处。 目前国内吉林石化公司的丙烯腈装置经过不断的优化运行，使得它的消耗、质量水平基本上达到国内先进水平。丙烯腈国内竞争也变得越来越激烈，只有对装置不断的优化，才能满足市场对丙烯腈产品越来越多的要求，才能在竞争中突出自己的优势，打败其他对手。 丙烯腈生产方式有很多种，其中传统方法[7-9]有： 1. 乙醛法 用氢氰酸、乙醛反应生成丙烯腈 CH2CHO+HCN→CH2CH2CNOH CH2CH2CNOH→CH2=CHCN+H2O 2.乙炔法 用氢氰酸、乙炔反应生成丙烯腈 C2H2+HCN→CH2=CHCN 传统方法都需要氢氰酸这一剧毒且难以运输和储存的药品为原料，且反应的副产物多，AN精制困难，所以逐渐被现代生产所淘汰。 现在制备丙烯腈的生产工艺主要有丙烯直接氨氧化工艺、丙烷直接氨氧化工艺和丙烷脱氢后再进行丙烯氨氧化工艺等工艺方法。 本课题的目的是为了在当今国内市场丙烯腈供不应求的状况下，试图找到一个对现在生产丙烯腈工艺中切实可行的可以提高丙烯腈产量的方法或者改进方式。从而能够应对或者改善未来可能出现的丙烯腈供不应求的局面，解决原料短缺问题。 本次课题的意义在于通过对国内外丙烯腈生产现状及市场调研、工艺方法的前景分析、丙烯氨氧化合成丙烯腈技术经济性分析等，只要我国丙烯进口资源有保障，丙烯氨氧化技术在我国还是拥有广阔的发展空间和发展前景的，从目前全球丙烯腈生产技术发展来看, 丙烯腈工业的原料和工艺向多元化、新技术方向发展，而丙烯氨氧化合成丙烯腈工艺的广泛应用将会在一定程度上缓解我国对于丙烯腈的供需压力。 图1为丙烯腈工艺流程图。 图1. 丙烯腈工艺流程图 二、研究现状和前景展望 目前，丙烯腈行业正处于吐故纳新时期，无论是原料的选择还是工艺的选取可谓百花齐放。虽然中国丙烯腈市场新建和扩建项目较多，产能增长都维持在较高水平线上，但是这还是无法弥补国内丙烯腈的需求缺口。我国国内生产的丙烯腈还是无法满足国内需求。即我国现有的丙烯腈生产能力还远不能满足国内的需求，仍需大量进口。在丙烯腈生产工艺方面，以烃为原料来制备丙烯腈的生产工艺主要有丙烯直接氨氧化工艺、丙烷直接氨氧化工艺和丙烷脱氢后再进行丙烯氨氧化工艺等工艺方法。虽然丙烷比丙烯要便宜很多而且资源较为丰富。但是由于丙烷很难活化，这导致其需要苛刻的操作条件和活性、选择性及稳定性均很高的催化剂。给生产带来了麻烦。而且丙烯腈的稳定性较丙烷差, 在工艺条件下容易生成不需要的碳氧化物和氮氧化物等副产物。这就给丙烷直接制备丙烯腈带来了很大挑战。 于是人们开始寻求更加高效科学的丙烯腈生产方式，随着煤制低碳烯烃以及Sohio工艺的日渐成熟，丙烯腈不再是奇货可居了。Sohio法制备丙烯腈与其他丙烯氨化工艺相比，具有易反应，收率高，反应杂质少，能用简单方法精制等优点，因此受到各国丙烯腈生产公司的青睐。世界上百分之95的丙烯腈生产公司均采用Sohio技术，在美国日本更是夸张的全部采用此等方法来生产丙烯腈。在现如今国内丙烯腈存在供应缺口的情况下，利用Sohio工艺制丙烯腈具备良好的盈利空间，但是Sohio工艺技术仍存在着一些不足。比如在催化剂的选择时有很多问题，目前用的最多的是钼铋-三氧化二铝。但是这种催化剂在不同温度和用量上会影响活性，这给研究带来了不小的挑战。 我国国内丙烯腈生产发展前景还是比较客观的。随着科学技术的不断提高，我国国内丙烯腈生产工艺技术也是日新月异。国家对于国内丙烯腈生产公司也是给予了诸多的帮助，这也为国内丙烯腈生产创造了良好的市场环境，有利于国内丙烯腈工艺的发展。但是，我们也要正视我们存在的一些问题。比如生产水平还没达到国际最高水准行列，我们的国内丙烯腈供应需求还存在着很大的漏洞。2012年我国丙烯腈产能127.7万吨／年，表观消费量达175.5万吨[10-12]，主要用于生产腈纶、ABS树脂等。中国丙烯腈市场新建和扩建项目较多，产能增长将维持较高水平，但是这还是无法弥补国内丙烯腈的需求缺口。预计到2017年，我国国内生产的丙烯腈供不应求的局面还将持续下去。 三、课题主要内容、拟解决的问题、研究特色和创新之处 1．主要内容 先查阅与丙烯腈的各种生产方法的中英文文献资料，完成文献综述；仔细认真翻译一篇与本设计相关的英文文献。接着论证并确定丙烯腈合成工段工艺流程。应用化工专业流程模拟软件对丙烯腈合成工段进行模拟，完成物料衡算、热量衡算以及设备设计或选型，并对设备布置进行设计。最后分别采用autoCAD和手工绘制丙烯腈合成工段的物料流程图、管道仪表流程图，设备条件图、精制工段设备布置图。 2．需解决的问题 1）提高自我文献检索和搜集信息能力。 2）如何更快的打通全流程模拟 3）反馈计算操作条件、设备参数等，使生产丙烯腈过程更加环保、操作过程更加安全、生产的产品更加合理。 3. 特色和创新 以美国BP公司、日本三菱化成公司为代表的主要丙烯腈生产商开始了以丙烯为原料的生产丙烯腈的技术开发工作。其中以Sohio工艺最受人们所接受并应用于工业生产。其主要特点是采用选择性烃的吸附分离体系的循环工艺，可将循环物流中的惰性气体和碳氧化物选择性除去，原料丙烷和丙烯100%回收，从而降低了生产成本[13-14]。 四、研究方法、步骤和措施 根据设计内容要求查阅丙烯腈的相关资料，包括其物理性质、化学性质和合成方法等方面。通过比较每种合成工艺的优缺点，确定一种可行的最佳产品方案、生产规模、工艺技术方案等。对Sohio生产丙烯腈工艺做出认识和研究，已保证设计的连贯性和正确性。查找关于丙烯腈的外文文献，选择一篇能够很好表达丙烯腈项目的英文文献进行翻译。接着对已经收集好的资料进行仔细阅读并整理，做出相关的文献综述。 用AutoCAD软件绘制各设备图和工艺流程图，之后用Aspenplus软件进行工艺流程的全流程模拟和优化，通过这个模拟优化做出可行的优化设计方案，可以有利于最后的方案选择。通过物料衡算得到物料关系和能量关系；以图表形式表达设计结果。 五、参考文献 [1] 罗保军, 周子平, 王美云. 丙烯腈的生产现状与发展趋势[J]. 化工科技市场, 2003, (10):11-14. [2] 韩秀山. 丙烯腈的应用[J]. 四川化工与腐蚀控制, 2000, 3(6):52-53. [3] 张廷深. 国内外丙烯腈供需概况[J]. 石油化工技术经济, 1999, (3):27-32. [4] 白尔铮. 丙烷氨氧化制丙烯腈催化剂及工艺进展[J]. 工业催化, 2004, 12(7):1-6. [5] 于豪瀚. 丙烯腈生产技术进展[J]. 石油化工设计,1995,12(1):1-24. [6] 张惠民, 赵震, 徐春明. 丙烷直接氨氧化制丙烯腈催化剂的研究进展[J]. 化学通报, 2005, 68(11):832-838. [7] Roussel H,M ehlomakulu B,Belhadj F,et al.Active sites characterization in mixed vanadium and iron antimonate oxide catalysts for propane ammoxidation[J].J.Catal, 2002, 205(1): 97-106 [8] 钱伯章. 丙烯腈产能分析与技术进展[J]. 上海化工, 2004, 29(3): 45-47 [9] 谢方友. 丙烷氨氧化制丙烯腈催化剂设计进展[J]. 工业催化, 2003, 11(8):38-42. [10] 崔小明. 国内外丙烯腈的供需现状及发展前景分析[J]. 石油化工技术与 经济, 2015, 31(5):18-23. [11] 黄金霞, 陆书来. 2014年丙烯腈市场分析[J]. 化学工业, 2015, (08): 36-9. [12] 黄金霞, 陆书来, 纪立春. 2013年丙烯腈生产与市场分析[J]. 化学工业, 2014, (04):36-40. [13] 兰友, 单永霞. 提高丙烯腈精制回收率的方法[J]. 河北化工, 2007, l30 (10):58-60. [14] 毕锡斌. 丙烯腈反应器收率影响因素的探讨[J]. 安徽化工, 2003, (4):46-4 8. 六、指导教师意见 指导教师： 年 月 日 七、所在专业审查意见 负责人： 年 月 日 八、学院审查意见 负责人： 年 月 日 6 设计任务书 课题名称 年产7万吨丙烯腈项目初步设计——合成工段工艺设计 系 别 专 业 姓 名 学 号 年 月 日至 年 月 日共 周 指导教师签字 系主任签字 年 月 日 一、 设计的内容 1. 查阅资料，阐述丙烯腈的各种生产方法，确定本设计丙烯腈合成工段工艺方案 2. 对丙烷制丙烯腈合成工段进行物料衡算、热量衡算、设备设计（选型）； 3. 以图纸形式表示各设计过程。 二、 设计的要求与数据 1.设计应当由文献资料综述、计算部分、图纸部分构成； 2.设计过程清楚、计算程序可行，论述和参数选择有理有据实，图纸正确合理。 三、设计（论文）应完成的工作 1. 查阅与丙烯腈的各种生产方法的中英文文献资料，完成文献综述；仔细认真翻译一篇与本设计相关的英文文献。 2. 论证并确定丙烯腈合成工段工艺流程。 3. 应用化工专业流程模拟软件对丙烯腈合成工段进行模拟，完成物料衡算、热量衡算以及设备设计或选型，并对设备布置进行设计。 4.分别采用autoCAD和手工绘制丙烯腈合成工段的物料流程图、管道仪表流程图，设备条件图、精制工段设备布置图。 四、设计（论文）进程安排及实习安排 序 号 （论文）各阶段名称 日 期 1 文献调研阶段：完成文献查阅、并做好文献综述、开题报告。 第3周-第4周 2 确定丙烯腈合成工段流程。 第5周-6周 3 丙烯腈合成工段物料和热量衡算、设备设计，设备布置设计。 第7周-第12周 4 绘制图纸；编写设计说明书。 第13周-第15周 5 准备答辩 第16周-第16周 五、应收集的资料、主要参考文献及实习地点 查阅相关的中英文文献、专利；阅读化工原理、反应工程、化工制图、化工设计等相关参考书。 Chemical Engineering and Processing 46(2007)918923Ammoxidation of propylene to acrylonitrile in abench-scale circulating fluidized bed reactor Yongqi Hu a,b,Fengyun Zhao b,Fei Wei a,Yong Jin aa Department of Chemical Engineering,Tsinghua University,Beijing 100084,Chinab Institute of Chemical and Pharmaceutical Engineering,Hebei University of Science and Technolgy,Shijiazhuang 050018,China Received 16 March 2007;received in revised form 21 May 2007;accepted 22 May 2007 Available online 29 May 2007AbstractThe ammoxidation of propylene to acrylonitrile over Mo-Bi/?-Al2O3catalyst was investigated in a bench-scale hot model riser reactor with7mm i.d.and 30m in length.Propylene conversion and product yields were investigated under various operation conditions and the optimumconditions have been found for the new type reactor.The results show that the efficiency of catalyst is increased by four times and the yield ofacrylonitrileisincreasedby3%fortypeAcatalystandby6.5%fortypeBcatalystincomparisonwithacommercialturbulentfluidizedbedreactor.The yield of acrylonitrile can be further increased through staged air feeding strategy.2007 Elsevier B.V.All rights reserved.Keywords:Propylene;Ammoxidation;Acrylonitrile;Circulating fluidized bed;Riser reactor1.IntroductionTheheterogeneousselectiveammoxidationofpropyleneintoacrylonitrile(AN)is one of the most commercially significantreactions.CH3CH CH2+NH3+32O2713723K,CatalystCH2CHCN+3H2O(1)The features of this reaction include that:(1)it is a highlyexothermalreaction,?H=512.5kJ/mol;(2)thedesiredprod-uctacrylonitrileisaintermediatewhichmayfurtherbeoxidizedintoCO2orCO,gasbackmixinginreactorwillcausetheoverox-idation of AN and thus,the decrease of AN yield;(3)it followsredox mechanism,i.e.,oxygen is supplied by catalyst in theform of lattice oxygen and subsequently the reduced catalyst isreoxidized(regenerated)by molecular oxygen 1.Corresponding author at:Institute of Chemical and Pharmaceutical Engi-neering,Hebei University of Science and Technolgy,Shijiazhuang 050018,China.Tel.:+86 311 88632175;fax:+86 311 88632175.E-mail addresses:,yongqi (Y.Hu).Turbulent fluidized bed(TFB)reactor has been employedfor propylene ammoxidation to synthesize AN for decades.Effective heat and mass transfer in TFB makes it advantageousover packed bed reactor on the control of reaction temperature.However,TFBstillsuffersfromsevereaxialgasandsolidsback-mixing,insufficientgasandsolidscontactandsmallthroughput.Moreover,it is difficult to build a catalyst regeneration region tomeet the requirement of redox reaction mechanism in TFB dueto highly backmixing of gas and solids.To solve these problems,obstacles such as shaped metal-lic articles,screens,grids,perforated plates,horizontal plates,pipes or the likes were laid in a catalyst bed to prevent thecoalescence or growth of bubbles,or to prevent the back mix-ing of gas,thereby improving the contact between the feedgas and the catalyst particles 26.However these methodsare not practical because the construction for laying the obsta-cles is complicated,and the mixing of the catalyst particlesis prevented by the obstacles and the distribution of the cat-alyst in the reactor becomes uneven in terms of space andtime,so that it is difficult to stably and continuously con-duct the operation 7.A loop fluidized bed reactor with bafflefor propylene ammoxidation was proposed and experimentallyexaminedbyChenetal.8.Atwostagefluidizedbedwasdevel-oped for improving gassolid contact,which can be applied in0255-2701/$see front matter 2007 Elsevier B.V.All rights reserved.doi:10.1016/j.cep.2007.05.009Y.Hu et al./Chemical Engineering and Processing 46(2007)918923919redox catalytic reaction such as the ammoxidation of propylene9.ThedisadvantagesofTFBcanbeovercomeinahigh-densitycirculating fluidized bed(CFB)riser reactor 7,1012.Circu-lating fluidized bed allows the spatial separation of propyleneammoxidation in the riser reactor and catalyst regeneration inthe downcomer to maintain catalyst in oxygen-rich state for fur-ther ammoxidation reaction.CFB riser operates under severaltimes higher gas velocity than TFB,which decreases gas back-mixing significantly.Staged addition of air can be permittedin CFB to control oxygen concentration along riser for opti-mal performance 12.In conventional fluid catalytic cracking(FCC),in which CFB is employed,the density of catalyst bedis relatively low,however,high density in riser reactor,aver-age catalyst fraction higher than 10%1315,is needed for thereaction of ammoxidation of propylene to acrylonitrile 7,10for which longer gassolid contact time is required than that forFCC.Moreover,high-density operation allows higher mass andheat transfer to guarantee the conversion under higher operatinggas velocity,and smaller in reactor size resulting in the decreasein construction cost 7.This paper reports hot-model experiments on the selectiveammoxidation of propylene to acrylonitrile over Mo-Bi/?-Al2O3in a CFB riser reactor under high-density condition.Conversions and product yields obtained in the reactor are com-pared with those measured in a commercial turbulent fluidizedbed.2.ExperimentalMo-Bi/?-Al2O3catalyst was used in the hot-model exper-iments.In order to obtain representative experimental results,the catalyst was taken from a commercial TFB reactor.Afteremployed for several months,the catalyst had been reaching itsstable state of activity.The properties of the catalyst are listedin Table 1.The bench-scale circulating fluidized bed reactor is shown inFig.1.It consisted of a riser reactor,a separator,a regenerator inwhich catalyst was reoxidized by air,and an electrical heatingfluidized bed bath.The riser,0.007m i.d.and 30m in length,was spiraled round the regenerator.The long riser can simulta-neouslyguaranteeahighergasvelocity(3m/s)andenoughgasresidencetime.Theriserinspiralingtypeinstalledinafluidizedheating bath,in order to maintain the isothermal conditions ofthe 30m riser reactor.The inclination of the spiral tube againstthe horizontal was about 5.The temperature fluctuation of thefluidized heating bath was controlled within 1K.There was aTable 1The physical properties of the Bi/Mo catalystParticle size distribution(%)45?m and 90?m8.5Density of particle(kg/m3)1800Specific surface area(m2/g)0.68Fig.1.Theschematicofthelaboratory-scalehigh-densitycirculatingfluidized-bed reactor.side air inlet on the riser at 10m from the entrance of feed toexamine the staged air feed.Theflowratesofpropylene,airandammoniawerecontrolledby mass flow controllers.The pipe of reactant air was placed inthe fluidized bed bath for preheating the reactant air,and thenthe air entered the bottom of the regenerator to fluidize the cat-alyst particles which flowed down to an injector.In the injector,reactant air and catalyst particles are mixed with propylene andammonia up to the riser.The amount of carried catalyst wascontrolled by the flow rate of secondary air at the bottom of theinjector.In the riser the ammoxidation of propylene occurred,then the catalyst particles were separated from the gas in theseparator and stored in a catalyst-collector.The catalyst parti-cles were returned to the regenerator in batch to be reoxidizedbytheregeneratingair.Thegaseousproductsfromtheseparatorwent to a combustor for venting or to an absorbing system foranalysis.The residence time distribution of gas in the riser reactor wasmeasuredbyapulseresponsemethodusingathermalconductiv-ity detector.The measured residence time distribution indicatedthat axial Peclet number(Pe)increased with gas velocity andwas larger than 1000 when gas velocity was higher than 2m/s,indicating that gas flow in the riser approached plug flow.Theaverage catalyst volume fraction in the reactor was determinedby weighing the catalyst in the riser after suddenly closing thegas feed.When gas velocity was 2.53.0m/s and pressure dropwas set to 0.03MPa,the typical average catalyst fraction was0.100.12,and the density of catalyst bed was 180216kg/m3,which was 510 times higher than that of FCC riser.Nakamuraet al.7 gave the density of catalyst bed was 100kg/m3ormore,andpreferable200kg/m3ormorefortheammoxidationofpropyleneinacirculatingfluidizedbedreactor.Althoughthereisa world of difference on the structure between the above experi-920Y.Hu et al./Chemical Engineering and Processing 46(2007)918923mentalriserreactorandcommercialscaleriser,thesimilarityontheflowregimes,gasvelocityandaveragecatalystfractiongivessupport to the demonstration on the effectiveness to improvethe yield of AN in fast fluidizing flow regime compared to inturbulent fluidizing flow regime.The gaseous products were collected in three 400ml 0.1NHNO3scrubbers at 273K.A temperature programmed FID gaschromatograph was used to analyze AN,ACL,ACN and ACA.The gaseous products were analyzed by a TCD gas chromato-graph.Yield of HCN was determined by the addition of NaOH,followed by titration with 0.01M AgNO3.Ammonia break-through was measured by titration of the HNO3scrubber with0.1N NaOH.3.Results and discussionsIn order to demonstrate the features of CFB riser reactor forthe ammoxidation of propylene to AN,hot model experimentswere made under different operation conditions:contact time,temperature,and feed ratio.The experiments with side feed ofair were also carried out.The results are discussed as follows.3.1.Effects of contact time on the product distributionProduct yield distributions are shown in Fig.2 as a functionof the contact time,W/F.Steep increases in both propylene con-version and AN yield are observed in the beginning stage ofreaction.A complete conversion is nearly reached at the contacttime longer than 125gcat.h/mol C3H6.WWH,the weight(kg)of reacted propylene per kilogram catalyst per hour,is usuallyused to represent the efficiency of catalyst in a certain reac-tor.For the catalyst used in the experiments,WWH is 0.065 incommercial TFB reactors.The contact time of 125gcat.h/molC3H6is equivalent to 0.33 in WWH,indicating that the capac-Fig.2.Changesinyieldofproductswithcontacttime:P=0.10MPa,T=718K,air/C3=10.5,NH3/C3=1.15.Fig.3.Changes in yield of AN with temperature:P=0.10MPa,air/C3=10.5,NH3/C3=1.15,W/F=125gh/mol.ity of the catalyst in CFB is about four times higher than that incommercial TFBs.As can be seen in Fig.2,increasing contact time,AN yieldincreasessignificantlyatbeginningreachesamaximumandthendecreasesgradually.TheyieldsofbothCOxandHCN,however,increase continuously with contact time,indicating that AN canfurther be oxidized to HCN and COxunder long contact time.ANisintermediateproduct,severegasbackmixingdecreaseANselectivity and yield.3.2.Effect of reaction temperatureFig.3 plots the effect of temperature on AN yield.The high-est yield can be achieved within the range of 708718K.Underlower temperature,AN yield is low due to the slow reactionrate and thus,the low conversion level;under higher temper-ature,overoxidation causes the decrease of AN yield.On theother hand,COxproduction steadily increases as the reactiontemperature increases.HCN yield changes insignificantly withthe increase of temperature.3.3.Effect of feed ratioAir/C3is an important controlling factor in industrial pro-cesses.Theoretically,air/C3ratio of 7.5 is enough for the mainreaction to produce AN,in which 1.5mol O2reacts with 1molpropylene.Due to the existence of side reaction,air/C3ratiois usually maintained between 10 and 10.5 in commercial TFBreactors.Fig.4 presents the effect of air/C3on AN yield.Anoptimumratioof9.510isfound.Itisslightlylowerthanthatintheindustrialprocess.Thisispartlybecausetheregeneratedcat-alystcarriedsomeamountofoxygeninlatticetypeintotheriser.Less overoxidation of AN resulted also in a low consumption ofoxygen.Y.Hu et al./Chemical Engineering and Processing 46(2007)918923921Fig.4.Changes in yield of AN with air/C3:P=0.10MPa,T=718K,NH3/C3=1.15,W/F=125gh/mol.NH3/C3ratio is also important in the synthesis of AN.MoreNH3in the reacting gas promotes N-containing products,espe-cially AN,and impedes O-containing products like COxandACL.The monotonous increase of AN yield and decrease ofCOxyield can be seen in Fig.5.NH3/C3ratio of 1.11.2 ispreferred.High NH3/C3ratio will increase the operation costin the product separation.3.4.Comparison with commercial TFB reactorTwo type of Mo-Bi/Al2O3catalysts was used in theexperiments.The experimental results from the experimentalhigh-density riser reactor and the data from commercial TFBreactors are shown in Table 2.The results from a small bubbleFig.5.Change in yield of AN with NH3/C3:P=0.10MPa,T=718K,air/C3=10.5,W/F=125gh/mol.fluidized bed(BFB)reactor for the evaluation of type A cat-alyst activity,provided by catalyst manufacturer,is also givenin this table.The experimental results indicate that comparedto the commercial TFB reactors,the high-density riser reactorhas the following features(1)the operating gas velocity reaches2.23m/s,the throughput of reactants is increased by more thanfourtimes;(2)theefficiencyofthecatalysts,WWH,isincreasedbyfourtimes;(3)ANyieldisincreasedby3%forthetypeAcat-alystandby6.5%fortheusedtypeBcatalyst,andtheproductionof COxare obviously decreased.The increases in reactor capac-ity and in WWH are mainly due to better gassolid contact inriserunderhigh-densitycondition,fullyregenerationofcatalystin regenerator and the higher concentration of reactant gases intheinletoftheriserreactor.TheincreaseinANyieldistheresultTable 2Comparison with commercial TFB reactorCatalyst(type A)Catalyst(used type B)HDCFB(reactor)TFB(reactor)BFB(reactor)HDCFB(reactor)TFB(reactor)T(K)716718718724722P(MPa)0.0810.050.050.050.05Air/C39.5210.59.710.08NH3/C31.191.151.121.03U(m/s)2.290.500.012.990.51Yield(%)AN83.3580.3376.875.268.68ACL0.310.10.00.79ACN2.793.081.592.48HCN5.665.9110.984.21COx6.9810.2111.5120.79X99.0999.6399.2896.95Balance in C1.041.08Balance in O0.990.98WWH0.3490.0650.4510.065922Y.Hu et al./Chemical Engineering and Processing 46(2007)918923Fig.6.Variations of AN yield with the fraction of oxygen side feed.ofnearlyplugflowintheriserunderhighergasvelocitythanthatin TFB.3.5.Experiments on staged air feedingEssentialplugflowandthustheexistenceofgradientofreac-tant concentration along riser make it possible to optimize thefeed policy and to get high selectivity of the desired product.Low concentration of oxygen along riser will reduce oxida-tion and favor ammoxidation,and thus will increase AN yield.However,considering that too low O2/C3ratio will cause over-reduction of catalyst to lost its activity,only 1030%of totalair was introduced through one side inlet at 10m of the riser inthe experiments.In order to maintain similar state of flow in theexperimentsunderdifferentsidefeedratio,theairfromsideinletwas replaced by 79%N2+21%O2and only O2was introducedfromthesideinletwhileN2enteredtheriseratthebottomoftheriser.Fig.6 shows the results of side oxygen feed experiments.Whentheexperimentsonsidefeedwerecarriedout,thecatalysthad been run for several months and had experienced too manytimes of the rise and drop in temperature due to the start andstop of experiment.The catalyst activity was not so good as atthe beginning,and AN yield under no side feed condition wasonly about 75%,as shown in Fig.6.Nevertheless,the increaseofnearly5%inANyieldwasobtainedwhen30%oxygenasthesidefeed,confirmingtheeffectivenessofstagedoxygenfeedingstrategy.4.ConclusionsHotmodelexperimentsweredoneonalaboratory-scalehigh-density CFB reactor with two kinds of Mo-Bi/?-Al2O3catalystundervariousoperationconditions.Theoptimumoperationcon-ditionsforhigh-densityriserreactoraretemperature708718K,air/propyleneratio9.5,NH3/propyleneratio1.11.2andcontacttime 125gh/mol C3H6.Compared with the commercial turbu-lent fluidized bed reactor,a high-density riser reactor has theadvantages including that(1)gas velocity reaches 2.23m/s,and the throughput of CFB reactor is increased more than fourtimes;(2)the efficiency of catalyst,WWH,is increased by fourtimes;(3)TheyieldsofANisincreasedby3%fortypeAcatalystand by 6.5%for type B catalyst,and the yield of COxis obvi-ouslydecreased.Stagedoxygenfeedingcanfurtherpromotetheincrease of AN yield.AcknowledgementsFinancial support from Petrochemical Company of China isgratefully acknowledged.The authors are also grateful to Pro-fessor Zhanwen Wang and Professor Zhiqing YU for their veryuseful discussion and to Mr.Hongwei Dian,Xiaotao Wan andYanhui Yang for their help on the experiments.Appendix A.NomenclatureACAacrylic acidACLacroleinACNacetonitrileair/C3mole ratio of air and C3H6(dimensionless)ANacrylonitrileCOxCO2+CONH3/C3mole ratio of NH3and C3H6(dimensionless)Ppressure at the exit of riser(MPa)Treaction temperature(K)Ugas velocity in riser(m/s)W/Fcontact time on the basis of C3H6,gcat.h/mol C3H6WWHthe weight(kg)of reacted propylene per kilogram cat-alyst per hourXconversion ratio of propyleneReferences1 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