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1、华东理工大学硕士学位论文第1页固定床吸附分离过程动态特性的研究摘要本文以固定床等温吸附过程为研究对象,根据体系的平衡关系和速率关系,建立描述过程的数学模型,求得模型方程的解来得到床层出口处的透过曲线的数学表达式,以此来研究吸附过程的动态特性。实验中采用醋酸水溶液一活性炭物系,使用计算机在线测量技术测定吸附质浓度。通过实验获得了多组温度下的吸附平衡曲线,这些曲线都服从兰缪尔(Langmuir)吸附等温方程。本文推导了三种传质模型,分别是恒定传质区模型:总传质系数模型;内扩散控制模型。恒定传质区模型以吸
2、附传质区浓度随轴向距离分布不变为依据,以传质系数K,“为模型参数。总传质系数模型以吸附等温线为直线、总传质系数为常数作为前提,以总传质系数Kfa为模型参数。内扩散控制模型假定液相传质阻力为零、吸附颗粒为球形,内扩散传质服从费克定律为条件,以内扩散系数D。为模型参数。在不同流速、进料浓度、温度、床高、吸附剂颗粒直径下,实验测定了固定床吸附器的透过曲线。采用适当的优化方法,对上述模型和实验透过曲线进行参数拟合,获得模型参数。对各模型参数K,a,Kfa,D,随操作条件的变化进行了讨论·最后,对各传质模型进
3、行了分析和评价·关键字:固定床吸附,吸附等温方程,动态特性,透过曲线,数学模型第n页华东理工大学硕士学位论文ResearchontheDynamicCharacterofAdsorptioninFixed-bedAbstractThedynamiccharacterofadsorptioninfixed-bedisstudiedinthiswork.Basedontheequilibriumequationsandvelocityequationsofthesystem,themathematica
4、lmodelsweresetupandfromthesolutionofthesemodelsthemathematicalexpressionofthebreakthroughcurveswereobtainedaswell.Aqueoussolutionofaceticacidandactivatedcarbonwereusedasexperimentsystem.Computeron-linemeasuretechniquewasalsoappliedtodeterminetheconcent
5、rationoftheadsorber.AdsorptionequilibriumcurveswereobtainedindiferenttemperatureandthesecurvesarefitforLangmuirisothermaladsorptionequation.Inthispaper,threemasstransfermodelsweresetup,whichwerefixedmasstransferzonemodel,mainmasstransfercoefficientmode
6、landinnerdiffusecontrolledmodel.ThefixedtransferzonemodelwasbasedonthehypothesisthattherewasafixedconcentrationdistributionintheaxialdirectioninthemasstransferzoneandtheparameterwasthemasstransfercoeficientK,a.Inthemainmasstransfercoeficientmodel,thepr
7、imaryassumptionswerethatthesystemhadalinerphraseequilibriumisothermandaconstantmasstransfercoefficientKfa·Intheinnerdiffusecontrolledmodel,itwassupposedthatthemasstransferresistanceinliquidphrasecouldbeneglected,adsorptionparticleswerespherical,theinne
8、rdifusionobeyedFick'slowandtheparameterwasdifusecoefficientD,.Breakthroughcurvesweregainedindifferentoperationconditionsasflowrate,heightofthefixedbed,temperatureofthebedanddiameteroftheadsorbentparticle.Properoptimizationmethodswereuse