专业英语 lesson

《专业英语 lesson 》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Lesson8PrinciplesofMembraneSeparation第8课膜分离原则1WhatisaMembrane?1什么是膜？Themembranecanbedefinedessentiallyasabarrier,whichseparatestwophasesandrestrictstransportofvariouschemicalsinaselectivemanner.Amembranecanbehomogenousorheterogeneous,symmetricorasymmetricinstructure,solidorliquid,canca

2、rryapositiveornegativechargeorbeneutralorbipolar.Transportthroughamembranecanbeeffectedbyconvectionorbydiffusionofindividualmolecules,inducedbyanelectricfieldorconcentration,pressureortemperaturegradient.Themembranethicknessmayvaryfromassmallas100microntoseveralmms.该膜基本上可以被定义为一个障碍，而两相分

3、离，并限制各种化学品运输有选择地。甲膜可以均匀或不均匀，对称或不对称的结构，固体或液体，可携带正或负电荷或中性或两极。通过膜交通可以通过对流或影响，由一个电场或浓度，压力或温度梯度引起的个别分子，扩散。膜的厚度可能不同，小到100微米到数彩信。2MembraneSeparationTechnology2膜分离技术Amembraneseparationsystemseparatesaninfluentstreamintotwoeffluentstreamsknownasthepermeateandtheconcentrate.Thepermeateistheporti

4、onofthefluidthathaspassedthroughthesemi-permeablemembrane.Whereastheconcentratestreamcontainstheconstituentsthathavebeenrejectedbythemembrane.一个膜分离系统分离成两个污水流作为集中的渗透和闻名的进水流。渗透液是已通过半透膜通过流体部分。鉴于集中流包含有被拒绝的膜成分。Membraneseparationprocessenjoysnumerousindustrialapplicationswiththefollowingadva

5、ntages:AppreciableenergysavingsEnvironmentallybenignCleantechnologywithoperationaleaseReplacestheconventionalprocesseslikefiltration,distillation,ion-exchangeandchemicaltreatmentsystemsProduceshigh,qualityproductsGreaterflexibilityindesigningsystems.膜分离过程工业的应用与众多享受如下优点:明显的节能有益于环保清洁技术与易

6、操作性代替了常规的过程(例如过滤、蒸馏、离子交换和化学处理系统生产出高质量的产品,设计系统以更大的灵活性3TypesofMembranes3不同的膜Theproperchoiceofamembraneshouldhedeterminedbythespecificapplicationobjective:particulateordissolvedsolidsremoval,hardnessreductionorultrapurewaterproduction,removalofspecificgases/chemicalsetc.Theend-usemayalsod

7、ictateselectionofmembranesforindustriessuchaspotablewater,effluenttreatment,desalinationorwatersupplyforelectronicsorpharmaceuticalmanufacturing.Thefollowingsectionexplainsthetypesofmembranescommonlyused.适当的选择应确定膜的具体应用目的:微粒或溶解固体颗粒的去除率也均、硬度减少或超纯水生产,移除特定的气体、化学品等。按用途也可支配膜的选择行业饮用水,废水处理,淡