多效精馏的原理及应用.pdf

e多效精储的原理及应用CP目录前言精储是化工生产中的一个能耗大户，为了降低其 能耗，可以采用多种措施，多效精微就是其中行之 有效的工艺之一。多效精馆是将精福塔分成能位不同的多塔，能位 较高塔的塔顶蒸汽向能位较低塔的再沸器供热，同 时它自己也被冷凝。这样，在多效精储中只是第一 个塔的塔釜需要加入热量，最后一个塔的塔顶蒸汽 用冷却介质进行冷凝，而其余各塔则不再需要由外 界进行供热和冷却,所以它具有非常明显的节能 效果。1 f 42多效精馆原理分离过程是一个不可逆过程，要实现混合物的 分离必须消耗一定的外功。分离过程的功耗存在 一个最低限度，即分离最小功。只有当分离 过程完全可逆时，分离消耗的功才是分离最小功。叱一是分离过程必须消耗的有效能的下限，而 实际过程的有效能消耗也要比叱mn大去多倍。用热力学效率来衡量有效能的利用率，即W T min,Tn 77=-2 f 42多效精馆原理对于精储操作，分离消耗的 是热能，而不是机械能。右图 简要示明了此分离过程。精福操作受温度右下向塔 釜加入的热量且驱动，同时 在冷凝器中于温度，下取走 热量4 O两者的有效能之差 为精镭操作的净功耗：叽二4ThQdTl3 f 42多效精馆原理由于热交换过程中推动力温 差存在造成的有效能损失七7。在塔顶冷凝器、塔底再沸器 和其他一些辅助换热设备中，均需有一定的传热推动力温差 存在。当的热量从温度为右 的热源传到温度为TL的热阱 时，其有效能损失为：(1 13Q 5QTl ThSDm=To可见，有效能损失与传热温差成正比4 f 42多效精馆原理例：在20atm丙烯丙烷精像过程中，塔顶丙烯冷凝温度 为48,塔釜丙烷沸点为57,二者温差为9,理论上净功耗 5为理论净功耗的6.1倍。5 f 42多效精馆原理F 1 F?z FnW2 Dn_i Wn多效精储原理6 f 42多效精储的节能效果多效精储的节能效果是以其效数来决定的。从理论上讲，与单塔相比，由双塔组成的双效精储的节 能效果为50%,而三效精镭的节能效果为67%,四效精 福的节能效果为75%o以此推，对于N效精馈，其节能效 果可用一个公式来表示：N-1=xlOO%N效数2345678910节能效果(%)5066.7758083.385.787.588.9907 f 42多效精储的节能效果当冷热介质间温差一定时，随着效数的增加，各效之间热 交换器的温差减小，因而传热 面积增加，给热交换器的设计 和加工制造带来一定的困难。,随着效数增加，节能效果增加 的越来越少。每增加一效，需 要增加塔和热交换器各一台，即随着效数增加,装置的投资费 用则越来越大;因此实际应用 中，以双效节能居多。负面影响8 f 42双效精储的流程分类平流双效精馈流程9 f 42双效精储的流程分类顺流双效精像流程100/42双效精懦的流程分类叫 R逆流双效精播流程11 f 42操作压力的影响双效精储操作压力的组合方式有三种：加压常压;加压减压;常压减压。选择操作压力应当遵循以下几 个原则：(a)操作温度和压力不能高于 塔的承受能力，应存有一定裕度。(b)对热敏性物质,前效塔釜温 度不能高于其热分解或聚合温度O(c)前效塔顶蒸汽和后效塔釜 间必须存在合理的温差,一般应 高于10c,以实现热量传递。另外,前效塔釜温度 最好低于可用的，价格 低廉的热源温度,以避 免用价格高昂的加热介 质;后效塔顶温度最好 低至可用循环水冷却。从这些方面着手设计可 在很大程度上降低单位 产品的投资和操作费用。12 f 42多效精储的应用某甲醇分离塔，要将质量分数为60%的甲醇水溶液提 纯。试分别采用单塔与双效塔进行分离，并比较当两种流 程产品一致时的能量利用情况。已知条件如下：进料温度为20,压力为101.325kPa,流率为 100kg/ho单塔的压力为塔L 325kPa,理论板数N=22,进 料理论板塔顶产品流率为63kg/h,摩尔回流比为 0.65 o(1)单塔流程 r-0COLUMN i-m13 f 42多效精储的应用Specifications v包o 会国nsetu白团。如。口。伫9-0伫9。母向 回 囹田用 团 ffi 田Simulation Options Stream Class Substreams Costing Options Stream Price Units-Sets Custom Units Report Options meritsSpeci i cati ons Assay/BlendLight-End Properties Petro Characterization P s eudo c omp orient s Attr-Comps Henry Comps Moi store Comps UNIFAC Groups Comp-Groups Comp-Listsa/Selection Petroleum Nonconventional/Enterprise Database|Component IDTypeComponent nameFormulaCH40MConventionalMETHA NOLCH 40H20ConventionalWA TERH20米Find Elec Wizard User Defined Reorder Review网Process Flo.Components.输入组分14 f 42多效精储的应用。Specificationsv S faG 口翩 nComponentsO Specifications|Assay/Blend Light-End Properties|Petro Characterization P s eudo c omp orient s Attr-Comps|Henry Comps Moi sture Comps UNIFAC Groups Comp-Groups Comp-Lists|Polymers Attr-ScalingProperti esO Speci i cationsy|Property Methods|Estimation|Molecular Structurev|Parameters|Pure ComponentE Binary Interaction/Global|Flowsheet Sections|ReferencedProperty methods&modelsProperty method:Process type:ICOMMON 1|nrtl B ase method:NRTL Henry components:Petroleum calculation optionsFree-water method:Water solubility:STEA M-TA Electrolyte calculation options Chemistry ID:|三“Use true-componentsI Modify property modelsQProcess Flo.Properties S.选择物性方法p厂厂15 f 42效精储的应用输入进料(FEED)条件孑的应用输入模块(COLUMN)参数17 f 42 多效精储的应用lerrrO Setupa.rm iruviV包坐METCBA RVG，会N,XSetupRate-based Distillation SetuDesign SpecsVaryHeaters CoolersPumparoundsDecantersEfficienciesReactionsCondenser HcurvesReboiler HcurvesNQ CurvesTray Si zingTray RatingPack SizingPack RatingPropertiesEstimatesConvergenceAnalysisReportFeed streamsNameStageConventionFEEDEil男A bove-StageProduct streamsNameStagePhaseBasis Flow UnitsFlow ratioFeed specsDIST1LiquidMoleFeed basisBOT22LiquidMole科Process Flo.Block COLU.输入模块(COLUMN)进料位置18 f 42g的应用g Setup V 包|塞|metcbar v|ah-V N回 COLUMN 4O Setup。Rate-based Distillation Setu Design Specs亡)VaryM Heaters CoolersPumparoundsDecantersM EfficienciesM Reactions|Condenser Hcurves Reboiler Hcurves亡NQ Curves|Tray Sizing|Tray Rating|Pack Sizing|Pack Rating，PropertiesM EstimatesM Convergence。Analysis四 Report4Configuration/Streams/Pressure/Condenser Therm口冲上|yReboiler|View:Top/BottomT op stage I Condenser pressureStage 1 I Condenser pressure:1101.325|kPaStage 2 pressure(optional)Q Stage 2 pressure:barC Condenser pressure drop:barPressure drop for rest of column(optional)Stage pressure drop:Column pressure drop:g|Process Flo.Block COLU.输入模块（COLUMN）压力19 f 42 多效精储的应用Q Results 向弱 v/NStreamsBlocks司 COLUMNResultsSummary Balance I Split FractionasaaaaaaProfiles Interface Profiles Efficiencies and HETP Transfer Coefficients Dimensionless Numbers EO Variables Stream Results Custom Stream ResultsResults Summary Run Status Strea/ns Convergence Utilities Custom Stream Summary Unit Operation Summary Equipment SummaryQDDaD科Process Flo.Control PanelBlock COLU.View:I Reboiler/Bottom stage 色 Basis:|Mole|Reboiler/Bottom stage performanceT emperature:Heat duty:Bottoms rate:Boilup rate:Boilup ratio:D100.017833 c(344559?|kW 二2.05380962|kmol/hr 二J3.56004431|kmol/hr 二|1.73338574Block COLU.查看再沸器结果20 f 42多效精储的应用Q Streams回重)v Results v H蒯等N+初 Streams日 Blocks-回 COLUMNResults Profiles|Interface Profiles Q Efficiencies and HETP Transfer Coefficients|Dimensionlews Numbers(.EO Variables Stream Results Custom Stream ResultsIts Summary Run Status Streams Convergence Utilities Custom Stream Summary Unit Operation Summary Equipment SummaryReSSDDSQMaterial|Display:口A ll streamsFormat:|GEN_M 二Stream Table二1二J|I dT emperature C100.065.820.0Pressure bar1.0131.0131.013Vapor Frac0.0000.0000.000Mole Flow kmol/hr2.0542.0394.093Mass Flow kg/hr37.00063.QUO100.000Volume Flow cum/hr0.0400.0840.116Enthalpy MMkcal/hr-0.137-0.116-0.259Mass FracCH 401 52PPBI 0.952 I0.600H201.0000.0480.400的Process Flo Control Panel Block COLU.Results Sum.查看物流结果21 f 42多效精储的应用(2)双效流程22 f 42多效精储的应用Specifications v包o 会国nsetu白团。如。口。伫9-0伫9。母向 回 囹田用 团 ffi 田Simulation Options Stream Class Substreams Costing Options Stream Price Units-Sets Custom Units Report Options meritsSpeci i cati ons Assay/BlendLight-End Properties Petro Characterization P s eudo c omp orient s Attr-Comps Henry Comps Moi store Comps UNIFAC Groups Comp-Groups Comp-Listsa/Selection Petroleum Nonconventional/Enterprise Database|Component IDTypeComponent nameFormulaCH40MConventionalMETHA NOLCH 40H20ConventionalWA TERH20米Find Elec Wizard User Defined Reorder Review网Process Flo.Components.输入组分23 f 42g的应用选择物性方法多效精储的应用输入进料(FEED)条件25 f 42孑的应用输入模块（B1）参数26 f 42多效精储的应用输入模块（B1）进料位置m效精储的应用输入模块（B1）操作压力28 f 42多效精储的应用Q1 V 百里|metcbar v|4s。y 口 年国 N的Process Fo.Block B1(Ra.田亡DISTI/Specifications Components 1 yFeed/Product StreamsOptions|Id亡DIST2EFEEDInputType:.1 二EO VariablesCustom Stream ResultsTarget:10,952l+li 1c0 uediiiESetup0 Product 厂 Internal)ecanterRate-based Distillation SetuDesi gn Specs 3 iVaryHeaters CoolersPumparounds DecantersEfficienciesReactionsCondenser HcurvesReboiler Hcurves规定低压塔塔顶产品纯度29 f 42g的应用输入Bl操纵变量效精储的应用输入模块（B2）参数)31 f 42 效精储的应用G A ll冷,XMETCBA R vO Setup田西AEaO Setup。Rate-based Distillation Setu|Design Specs二j VaryM Heaters Coolers|Pumparounds|Decanters。Efficiencies O ReactionsCondenser Hcurves f Reboiler Hcurves:J NQ Curves 二Tray Sizing Tray Rating|Pack Si zing Pack Rating。Properties O Estimates M Convergence，AnalysisQProcess Flo.Block B2(Ra.Configuration yStreams Pressure 4CondenserFeed streamsNameStageConventionFEED23A bove-Stage|Reboiler|Product streamsNameStagePhaseBasis Flow UnitsFIoaDIST21LiquidMolekmol/hrBOT212LiquidMole输入模块(Bl)进出物流位置参数32 f 42g的应用句i SetupV包萋 METCBA R vP A ll v 国N囤电）人 y Configuration Streams yPressure/Condenser|yReboiler 3-PhE)O Blocks 田必Bl B a B2 Setup Rate-based Distillation Setu Desi gn Specs d 1Vary d 1 Heaters Coolers Pumparounds Decanters Efficiencies Reactions Condenser Hcurves Reboiler Hcurves NQ Curves Tray Sizing Tray Rating Pack Sizing Pack Rating Properties/Specifications)mponents|Results|A djusted variableType:|Reflux ratioUpper and lower boundsLower bound:0.5Upper bound:5OptionalMaximum step size:阿gProcess Flo.Block B2(Ra.J输入B2操纵变量35 f 42多效精储的应用.Setup 回闺|METCBA R y|NStreams Blocks 囹Bl+Design Specs ffi 团 Vary Results Profiles|Interface ProfilesEfficiencies and HETPI_1 Transfer Coefficients|Dimensionless Numbers 3 EO Variables|I Stream Results|Custom Stream ResultsPUMPResults Summary Run Status Streams Convergence Utilities Custom Stream SummarySummary Balance Split FractionView:|Reboiler-Bottom stage Basis:|Mole Reboiler/Bottom stage performanceT emperature:|78,1585692cHeat duty:|22 9204248|kW Bottoms rate:3.05092934kmol/hrBoilup rate:|2.1608137kmol/hrBoilup ratio:10,7082477ra的Process Flo Control Panel Block PUMP.Block B1(Ra.查看模块（B1）再沸器结果37 f 42女精储的应用Q|Results v 包里 口图 N十回 日MB1电电aaaaaa3EaaB2团团aaaara 囹田田 囹中囹Desi gn SpecsVaryResultsProfilesInterface ProfilesEfficiencies and HETP Transfer Coefficients Dimensionless Numbers EO Variables Stream ResultsCustom Stream ResultsDesi gn SpecsVaryResultsProfilesInterface Profiles Efficiencies and HETP Transfer CoefficientsSummary Balance|Split Fraction|View:|Condenser/Top stageBasis:|Mole|Condenser/Top stage performanceT emperature:Heat duty:7.462492 kWSubcooled duty:Distillate rate:0.99770048 kmol/hrReflux rate:1.94973886 kmol/hrReflux ratio:1.95423267Free water distillate rate:Free water reflux ratio:附Process Flo.Control Panel|Block PUMP.Block B2(Ra.查看模块（B2）冷凝器结果多效精储的应用Q Results 包用 v 寸|Results 网 电 NStreamsBB1囹回QaQana3sE!B2团团aaaQKa 囹出？：,；囹1|田Design SpecsVaryResultsProfilesInterface ProfilesEfficiencies and HETP Transfer Coefficients Dimensionless Numbers EO Variables Stream ResultsCustom Stream ResultsDesi gn SpecsVaryResultsProfilesInterface Profiles Efficiencies and HETP Transfer CoefficientsSummary Balance|Split FractionView:|Reboiler/Bottom stage 二|Basis:|Mole色Rsboiler/Bottom stdge performanceT emperature:135.726899C,Heat duty:31.2546092kW 二Bottoms rate:2.05322886kmol/hr _Boilup rate:2.88273216kmol/hr Boilup ratio:1.40399943时|Process Flo.Control PanelBlock PUMP.Block B2(Ra.|查看模块（B2）再沸器结果39 f 42多效精储的应用suits Sum.MaterialHeat|LoadCurves|Petro.Curves|Poly.Curves|Display:A ll streamsTJFormat:|GEN_M 1Stream Table I|B0T2二I|DIST1 IT emperalure C78.2135.765.898.320.078.4Pressure bar1.0133.2001.0133.2001.0133.200Vapor Frac0.0000.0000.0000.0000.0000.000Mole Flow kmol/hr3.0512.0531.0420.9984.0933.051Mass Flow kg/hr67.81737.000i 32.1833Q.817100.00067.817Volume Flow cum/hr0.0820.0420.0430.0440.1160.082Enthalpy MMkcal/hr-0.195-0.136-0.059-0.056-0.259-0.195Mass FracCH 400.433649 PPMI 0.952H9520.6000.433H200.567F 0.9990.0480.0480.4000.567查看物流结果40 f 42多效精储的应用单塔与多效精福分离甲醇模拟结果项目甲醇一水单塔双效塔1塔2压力(kPa)101.325101.325320Nt221012Nf1158塔顶 D(kg/h)6332.230.8塔顶Td()98.3塔釜Tw()10078.2135.7冷凝器Qc27.5再沸器Qr40.3422.931.3前效塔顶蒸汽和后效塔釜间 必须存在合理的温差,一般应高 于10C,以实现热量传递。校验：98.3-78.2=20.1210比较单塔流程和双塔流程 的结果，可得到甲醇提纯双 效精储彳遐的节能效果为:40.34 31.3 40.34-xl00%=22.41%41 f 42 4242f化学工业.模拟实训-AspenPlus教程孙兰义主编原理陈敏恒等编著化学工业.化工流程化工热力学马沛生编著化学工业.化工化工分离工程邓修吴俊生编著科学.分离过程与模拟刘家祺编著清华大学.参考文献