年產7萬噸丙烯腈項目合成工段設計

喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請放心下載，，有疑問咨詢QQ:1064457796或者1304139763 ==================== 喜歡就充值下載吧。。資源目錄里展示的文件全都有，，請放心下載，，有疑問咨詢QQ:1064457796或者1304139763 ==================== 開題報告 題 目： 年產7萬噸丙烯腈項目初步設計 －合成工段工藝設計 專 業： 姓 名： 學 號： 指導教師： 年 月 開 題 報 告 一、課題的目的與意義 丙烯腈是三大合成材料—合成纖維、合成橡膠、合成塑料的基礎原料[1]，這使得丙烯腈的地位逐年提高，所以丙烯腈生產及其深加工日益受到人們的重視。丙烯腈的生產方式有很多種，丙烯直接氨氧化工藝、丙烷直接氨氧化工藝和丙烷脫氫后再進行丙烯氨氧化工藝等工藝方法。其中利用丙烯氨氧化生產丙烯腈是丙烯腈生產的主要方式之一[2-3]。這種方法設備簡單，原料易得。反應所用到的丙烯是重要的石油化工基礎原料，因此研究丙烯腈生產過程，提高丙烯腈產品質量，降低丙烯腈原料消耗就顯得十分重要了。 我國丙烯腈的總需求量也將以年均10.8%的速率遞增。中國丙烯腈市場新建和擴建項目較多，產能增長將維持較高水平，但是這還是無法彌補國內丙烯腈的需求缺口[4-6]。預計到2017年，我國國內生產的丙烯腈還是無法滿足國內需求。即我國現有的丙烯腈生產能力還遠不能滿足國內的需求，仍需大量進口。因此 , 加大對丙烯腈生產工藝技術和催化劑體系的研究開發力度, 不斷提升我國丙烯腈生產的技術水平 ,是解決我國丙烯腈供需的平衡是關鍵之處。 目前國內吉林石化公司的丙烯腈裝置經過不斷的優化運行，使得它的消耗、質量水平基本上達到國內先進水平。丙烯腈國內競爭也變得越來越激烈，只有對裝置不斷的優化，才能滿足市場對丙烯腈產品越來越多的要求，才能在競爭中突出自己的優勢，打敗其他對手。 丙烯腈生產方式有很多種，其中傳統方法[7-9]有： 1. 乙醛法 用氫氰酸、乙醛反應生成丙烯腈 CH2CHO+HCN→CH2CH2CNOH CH2CH2CNOH→CH2=CHCN+H2O 2.乙炔法 用氫氰酸、乙炔反應生成丙烯腈 C2H2+HCN→CH2=CHCN 傳統方法都需要氫氰酸這一劇毒且難以運輸和儲存的藥品為原料，且反應的副產物多，AN精制困難，所以逐漸被現代生產所淘汰。 現在制備丙烯腈的生產工藝主要有丙烯直接氨氧化工藝、丙烷直接氨氧化工藝和丙烷脫氫后再進行丙烯氨氧化工藝等工藝方法。 本課題的目的是為了在當今國內市場丙烯腈供不應求的狀況下，試圖找到一個對現在生產丙烯腈工藝中切實可行的可以提高丙烯腈產量的方法或者改進方式。從而能夠應對或者改善未來可能出現的丙烯腈供不應求的局面，解決原料短缺問題。 本次課題的意義在于通過對國內外丙烯腈生產現狀及市場調研、工藝方法的前景分析、丙烯氨氧化合成丙烯腈技術經濟性分析等，只要我國丙烯進口資源有保障，丙烯氨氧化技術在我國還是擁有廣闊的發展空間和發展前景的，從目前全球丙烯腈生產技術發展來看, 丙烯腈工業的原料和工藝向多元化、新技術方向發展，而丙烯氨氧化合成丙烯腈工藝的廣泛應用將會在一定程度上緩解我國對于丙烯腈的供需壓力。 圖1為丙烯腈工藝流程圖。 圖1. 丙烯腈工藝流程圖 二、研究現狀和前景展望 目前，丙烯腈行業正處于吐故納新時期，無論是原料的選擇還是工藝的選取可謂百花齊放。雖然中國丙烯腈市場新建和擴建項目較多，產能增長都維持在較高水平線上，但是這還是無法彌補國內丙烯腈的需求缺口。我國國內生產的丙烯腈還是無法滿足國內需求。即我國現有的丙烯腈生產能力還遠不能滿足國內的需求，仍需大量進口。在丙烯腈生產工藝方面，以烴為原料來制備丙烯腈的生產工藝主要有丙烯直接氨氧化工藝、丙烷直接氨氧化工藝和丙烷脫氫后再進行丙烯氨氧化工藝等工藝方法。雖然丙烷比丙烯要便宜很多而且資源較為豐富。但是由于丙烷很難活化，這導致其需要苛刻的操作條件和活性、選擇性及穩定性均很高的催化劑。給生產帶來了麻煩。而且丙烯腈的穩定性較丙烷差, 在工藝條件下容易生成不需要的碳氧化物和氮氧化物等副產物。這就給丙烷直接制備丙烯腈帶來了很大挑戰。 于是人們開始尋求更加高效科學的丙烯腈生產方式，隨著煤制低碳烯烴以及Sohio工藝的日漸成熟，丙烯腈不再是奇貨可居了。Sohio法制備丙烯腈與其他丙烯氨化工藝相比，具有易反應，收率高，反應雜質少，能用簡單方法精制等優點，因此受到各國丙烯腈生產公司的青睞。世界上百分之95的丙烯腈生產公司均采用Sohio技術，在美國日本更是夸張的全部采用此等方法來生產丙烯腈。在現如今國內丙烯腈存在供應缺口的情況下，利用Sohio工藝制丙烯腈具備良好的盈利空間，但是Sohio工藝技術仍存在著一些不足。比如在催化劑的選擇時有很多問題，目前用的最多的是鉬鉍-三氧化二鋁。但是這種催化劑在不同溫度和用量上會影響活性，這給研究帶來了不小的挑戰。 我國國內丙烯腈生產發展前景還是比較客觀的。隨著科學技術的不斷提高，我國國內丙烯腈生產工藝技術也是日新月異。國家對于國內丙烯腈生產公司也是給予了諸多的幫助，這也為國內丙烯腈生產創造了良好的市場環境，有利于國內丙烯腈工藝的發展。但是，我們也要正視我們存在的一些問題。比如生產水平還沒達到國際最高水準行列，我們的國內丙烯腈供應需求還存在著很大的漏洞。2012年我國丙烯腈產能127.7萬噸／年，表觀消費量達175.5萬噸[10-12]，主要用于生產腈綸、ABS樹脂等。中國丙烯腈市場新建和擴建項目較多，產能增長將維持較高水平，但是這還是無法彌補國內丙烯腈的需求缺口。預計到2017年，我國國內生產的丙烯腈供不應求的局面還將持續下去。 三、課題主要內容、擬解決的問題、研究特色和創新之處 1．主要內容 先查閱與丙烯腈的各種生產方法的中英文文獻資料，完成文獻綜述；仔細認真翻譯一篇與本設計相關的英文文獻。接著論證并確定丙烯腈合成工段工藝流程。應用化工專業流程模擬軟件對丙烯腈合成工段進行模擬，完成物料衡算、熱量衡算以及設備設計或選型，并對設備布置進行設計。最后分別采用autoCAD和手工繪制丙烯腈合成工段的物料流程圖、管道儀表流程圖，設備條件圖、精制工段設備布置圖。 2．需解決的問題 1）提高自我文獻檢索和搜集信息能力。 2）如何更快的打通全流程模擬 3）反饋計算操作條件、設備參數等，使生產丙烯腈過程更加環保、操作過程更加安全、生產的產品更加合理。 3. 特色和創新 以美國BP公司、日本三菱化成公司為代表的主要丙烯腈生產商開始了以丙烯為原料的生產丙烯腈的技術開發工作。其中以Sohio工藝最受人們所接受并應用于工業生產。其主要特點是采用選擇性烴的吸附分離體系的循環工藝，可將循環物流中的惰性氣體和碳氧化物選擇性除去，原料丙烷和丙烯100%回收，從而降低了生產成本[13-14]。 四、研究方法、步驟和措施 根據設計內容要求查閱丙烯腈的相關資料，包括其物理性質、化學性質和合成方法等方面。通過比較每種合成工藝的優缺點，確定一種可行的最佳產品方案、生產規模、工藝技術方案等。對Sohio生產丙烯腈工藝做出認識和研究，已保證設計的連貫性和正確性。查找關于丙烯腈的外文文獻，選擇一篇能夠很好表達丙烯腈項目的英文文獻進行翻譯。接著對已經收集好的資料進行仔細閱讀并整理，做出相關的文獻綜述。 用AutoCAD軟件繪制各設備圖和工藝流程圖，之后用Aspenplus軟件進行工藝流程的全流程模擬和優化，通過這個模擬優化做出可行的優化設計方案，可以有利于最后的方案選擇。通過物料衡算得到物料關系和能量關系；以圖表形式表達設計結果。 五、參考文獻 [1] 羅保軍, 周子平, 王美云. 丙烯腈的生產現狀與發展趨勢[J]. 化工科技市場, 2003, (10):11-14. [2] 韓秀山. 丙烯腈的應用[J]. 四川化工與腐蝕控制, 2000, 3(6):52-53. [3] 張廷深. 國內外丙烯腈供需概況[J]. 石油化工技術經濟, 1999, (3):27-32. [4] 白爾錚. 丙烷氨氧化制丙烯腈催化劑及工藝進展[J]. 工業催化, 2004, 12(7):1-6. [5] 于豪瀚. 丙烯腈生產技術進展[J]. 石油化工設計,1995,12(1):1-24. [6] 張惠民, 趙震, 徐春明. 丙烷直接氨氧化制丙烯腈催化劑的研究進展[J]. 化學通報, 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] 錢伯章. 丙烯腈產能分析與技術進展[J]. 上?；? 2004, 29(3): 45-47 [9] 謝方友. 丙烷氨氧化制丙烯腈催化劑設計進展[J]. 工業催化, 2003, 11(8):38-42. [10] 崔小明. 國內外丙烯腈的供需現狀及發展前景分析[J]. 石油化工技術與 經濟, 2015, 31(5):18-23. [11] 黃金霞, 陸書來. 2014年丙烯腈市場分析[J]. 化學工業, 2015, (08): 36-9. [12] 黃金霞, 陸書來, 紀立春. 2013年丙烯腈生產與市場分析[J]. 化學工業, 2014, (04):36-40. [13] 蘭友, 單永霞. 提高丙烯腈精制回收率的方法[J]. 河北化工, 2007, l30 (10):58-60. [14] 畢錫斌. 丙烯腈反應器收率影響因素的探討[J]. 安徽化工, 2003, (4):46-4 8. 六、指導教師意見 指導教師： 年 月 日 七、所在專業審查意見 負責人： 年 月 日 八、學院審查意見 負責人： 年 月 日 6 設計任務書 課題名稱 年產7萬噸丙烯腈項目初步設計——合成工段工藝設計 系 別 專 業 姓 名 學 號 年 月 日至 年 月 日共 周 指導教師簽字 系主任簽字 年 月 日 一、 設計的內容 1. 查閱資料，闡述丙烯腈的各種生產方法，確定本設計丙烯腈合成工段工藝方案 2. 對丙烷制丙烯腈合成工段進行物料衡算、熱量衡算、設備設計（選型）； 3. 以圖紙形式表示各設計過程。 二、 設計的要求與數據 1.設計應當由文獻資料綜述、計算部分、圖紙部分構成； 2.設計過程清楚、計算程序可行，論述和參數選擇有理有據實，圖紙正確合理。 三、設計（論文）應完成的工作 1. 查閱與丙烯腈的各種生產方法的中英文文獻資料，完成文獻綜述；仔細認真翻譯一篇與本設計相關的英文文獻。 2. 論證并確定丙烯腈合成工段工藝流程。 3. 應用化工專業流程模擬軟件對丙烯腈合成工段進行模擬，完成物料衡算、熱量衡算以及設備設計或選型，并對設備布置進行設計。 4.分別采用autoCAD和手工繪制丙烯腈合成工段的物料流程圖、管道儀表流程圖，設備條件圖、精制工段設備布置圖。 四、設計（論文）進程安排及實習安排 序 號 （論文）各階段名稱 日 期 1 文獻調研階段：完成文獻查閱、并做好文獻綜述、開題報告。 第3周-第4周 2 確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熱量衡算、設備設計，設備布置設計。 第7周-第12周 4 繪制圖紙；編寫設計說明書。 第13周-第15周 5 準備答辯 第16周-第16周 五、應收集的資料、主要參考文獻及實習地點 查閱相關的中英文文獻、專利；閱讀化工原理、反應工程、化工制圖、化工設計等相關參考書。 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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