大學化工專業(yè)英語Lesson-1

..ChemicalEngineeringChemicalengineeringisthedevelopmentofprocessesandthedesignandoperationofplantsinwhichmaterialsundergochangesinphysicalorchemicalstateonatechnicalscale.化學工程是過程的開發(fā)和工廠的設(shè)計與操作,在工廠中材料以某種技術(shù)規(guī)模進行的物理或化學狀態(tài)的變化。Appliedthroughouttheprocessindustries,itisfoundedontheprinciplesofchemical,physics,andmathematics.它建立在化學、物理和數(shù)學的原則上,適用于整個流程工業(yè)。Thelawsofphysicalchemistryandphysicsgovernthepracticabilityandefficiencyofchemicalengineeringoperations.物理化學和物理定律支配著化工業(yè)務的實用性和效率。Energychanges,derivingfromthermodynamicconsiderations,areparticularlyimportant.能量的變化,從熱力學考慮派生,顯得尤其重要。Mathematicsisabasictoolinoptimizationandmodeling.數(shù)學是一個優(yōu)化和建模的基本工具。Optimizationmeansarrangingmaterials,facilities,andenergytoyieldasproductiveandeconomicalanoperationaspossible.優(yōu)化意味著合理安排材料、設(shè)備和能源,盡可能生產(chǎn)經(jīng)濟多產(chǎn)的操作。Modelingistheconstructionoftheoreticalmathematicalprototypesofcomplexprocesssystems,commonlywiththeaidofcomputers.建模是將復雜過程系統(tǒng)建設(shè)出其理論數(shù)學原型的過程,通常需要借助電腦完成。Chemicalengineeringisasoldastheprocessindustries.化學工程和過程工業(yè)一樣古老。Itsheritagedatesfromthefermentationandevaporationprocessesoperatedbyearlycivilizations.其遺產(chǎn)起源于早期文明的發(fā)酵和蒸發(fā)過程。Modernchemicalengineeringemergedwiththethedevelopmentoflarge-scale,chemical-manufacturingoperationsinthesecondhalfofthe19thcentury.在19世紀下半葉,隨著大規(guī)模的化學制造業(yè)操作的發(fā)展,現(xiàn)代化學工程出現(xiàn)了。Throughoutitsdevelopmentasanindependentdiscipline,chemicalengineeringhasbeendirectedtowardsolvingproblemsofdesigningandoperatinglargeplantsforcontinuousproduction.化學工程作為一門獨立的學科,縱觀其發(fā)展過程,它已經(jīng)朝向解決設(shè)計問題和經(jīng)營連續(xù)生產(chǎn)的大型工廠的問題。Manufactureofchemicalsinthemid-19thcenturyconsistedofmodestcraftoperations.在19世紀中葉,化工生產(chǎn)由小型的手工操作組成。Increaseindemand,publicconcernattheemissionofnoxiouseffluents,andcompetitionbetweenrivalprocessesprovidedtheincentivesforgreaterefficiency.需求的增加,公眾對有害物質(zhì)排放的關(guān)注,和與對手的競爭過程為創(chuàng)造更高效率提供了激勵機制。Thisledtotheemergenceofcombineswithresourcesforlargeroperationsandcausedthetransitionfromacrafttoascience-basedindustry.這導致了更大的操作與資源相結(jié)合的聯(lián)合工廠的出現(xiàn),引起了從手工業(yè)到一個以科學為基礎(chǔ)的產(chǎn)業(yè)〔科技工廠的過渡。Theresultwasademandforchemistswithknowledgeofmanufacturingprocesses,knownasindustrialchemistsorchemicaltechnologists.其結(jié)果是應了具有制作過程知識的化學家的要求,這是為工業(yè)化學家或化工技師所知曉的Thetermchemicalengineerwasingeneralusebyabout1900.化學工程師一詞廣泛應用了約1900年。Despiteitsemergenceintraditionalchemicalsmanufacturing,itwasthroughitsroleinthedevelopmentofthepetroleumindustrythatchemicalengineeringbecamefirmlyestablishedasauniquediscipline.盡管出現(xiàn)在傳統(tǒng)的化學品制造中,但它的價值卻是通過其在石油工業(yè)——這門由化工工程牢固建立成的獨立學科來實現(xiàn)的。Thedemandforplantscapableofoperatingphysicalseparationprocessescontinuouslyathighlevelsofefficiencywasachallengethatcouldnotbemetbythetraditionalchemistormechanicalengineer.工廠的需求是能夠高效連續(xù)地進行物理分離過程的操作,這是傳統(tǒng)的化學家或工程師無法迎接的挑戰(zhàn)。Alandmarkinthedevelopmentofchemicalengineeringwasthepublicationin1901ofthefirsttextbookonthesubject,byGeorgeE.Davis,aBritishchemicalconsultant.化學工程發(fā)展的一個里程碑是1901年,一個英國化學顧問喬治·E·戴維斯出版的關(guān)于此話題的教科書。Thisconcentratedonthedesignofplantitemsforspecificoperations.這本書集中描述了設(shè)計工廠項目的具體操作。Thenotionofaprocessingplantencompassinganumberofoperations,suchasmixing,evaporation,andfiltration,andoftheseoperationsbeingessentiallysimilar,whatevertheproduct,ledtotheconceptofunitoperations.注意到加工廠包括的一系列操作,如混合、蒸發(fā)、過濾,無論產(chǎn)物是什么,這些操作都基本相同,從而導致了單元操作的概念。ThiswasfirstenunciatedbytheAmericanchemicalengineerArthurD.Littlein1915andformedthebasisforaclassificationofchemicalengineeringthatdominatedthesubjectforthenext40years.這被美國化學工程師理特于1915年首次解釋,形成了化學工程分類的基礎(chǔ),主導了未來40年的主題。Thenumberofunitoperations—thebuildingblocksofachemicalplant—isnotlarge.單元操作的數(shù)目——一個化工廠的建設(shè)模塊數(shù)并不大。Thecomplexityarisesfromthevarietyofconditionsunderwhichtheunitoperationsareconducted.復雜性來自于單元操作進行的條件的多樣性。Inthesamewaythatacomplexplantcanbedividedintobasicunitoperations,sochemicalreactionsinvolvedintheprocessindustriescanbeclassifiedintocertaingroups,orunitprocesses<e.g.,polymerizations,esterifications,andnitrations>,havingcommoncharacteristics.同復雜的工廠可劃分為基本的單元操作一樣,過程工業(yè)中涉及到的化學反應也可分成一定的單元過程〔如聚合、酯化和硝化,它們具有共同的特性。Thisclassificationintounitprocessesbroughtrationalizationtothestudyofprocessengineering.單元過程的這種分類對于過程工程的研究是合理的。Theunitapproachsufferedfromthedisadvantageinherentinsuchclassification:arestrictedoutlookbasedonexistingpractice.單元方法遭受這種分類固有的缺點：基于現(xiàn)行方法的限制性前景。SinceWorldWarⅡ,closerexaminationofthefundamentalphenomenainvolvedinthevariousunitoperationshasshownthesetodependonthebasiclawsofmasstransfer,heattransfer,andfluidflow.世界二戰(zhàn)以來,仔細觀察各種單元操作中包含的基本現(xiàn)象已經(jīng)表明,這取決于傳質(zhì)、傳熱和流體流動的基本規(guī)律。Thishasgivenunitytothediverseunitoperationsandhasledtothedevelopmentofchemicalengineeringscienceinitsownright;asaresult,manyapplicationshavebeenfoundinfieldsoutsidethetraditionalchemicalindustry.這統(tǒng)一了各種各樣的單元操作,導致了化學工程科學的正確發(fā)展。結(jié)果是,在傳統(tǒng)化學工廠之外的領(lǐng)域發(fā)現(xiàn)了許多應用。Studyofthefundamentalphenomenauponwhichchemicalengineeringisbasedhasnecessitatedtheirdescriptioninmathematicalformandhasledtomoresophisticatedmathematicaltechniques.研究化工依賴的基本現(xiàn)象需采用數(shù)學形式來描述,并借助復雜的數(shù)學技術(shù)來解決。Theadventofdigitalcomputershasallowedlaboriousdesigncalculationstobeperformedrapidly,openingthewaytoaccurateoptimizationofindustrialprocesses.電子計算機的出現(xiàn),使辛苦的設(shè)計計算工作能夠快速進行,為工業(yè)生產(chǎn)工藝的精確優(yōu)化開辟了道路。Variationsduetodifferentparameters,suchasenergysourceused,plantlayout,andenvironmentalfactors,canbepredictedaccuratelyandquicklysothatthebestcombinationcanbechosen.如所用的能源來源、工廠布置和環(huán)境因素這樣的不同參數(shù)引起的變化可正確和快速地得到預測,就可能選擇出最佳的組合。ChemicalEngineeringFunctions.Chemicalengineersareemployedinthedesignanddevelopmentofbothprocessesandplantitems.化學工程師主要設(shè)計和開發(fā)流程和工廠項目。Ineachcase,dataandpredictionsoftenhavetobeobtainedorconfirmedwithpilotexperiments.在每種情況下,數(shù)據(jù)和預測經(jīng)常能夠通過先導性的實驗被獲得和預測。Plantoperationandcontrolisincreasinglythesphereofthechemicalengineerratherthanthechemist.工廠操作和控制日益成為化學工程師的領(lǐng)域,而不是化學家的領(lǐng)域。Chemicalengineeringprovidesanidealbackgroundfortheeconomicevaluationofnewprojectsand,intheplantconstructionsector,formarketing.化學工程為新項目的經(jīng)濟評價和工程建設(shè)方面的營銷提供了理想的背景。BranchesofChemicalEngineering.Thefundamentalprinciplesofchemicalengineeringunderlietheoperationofprocessesextendingwellbeyondtheboundariesofthechemicalindustry,andchemicalengineersareemployedinarangeofoperationsoutsidetraditionalareas.化學工程的基本原則成為延伸到化學工業(yè)的邊界之外的過程操作的基礎(chǔ),化學工程師從事傳統(tǒng)領(lǐng)域之外的一系列操作。Plastics,polymers,andsyntheticfibersinvolvechemicalreactionengineeringproblemsintheirmanufacture,withfluidflowandheattransferconsiderationsdominatingtheirfabrication.塑料、聚合物和合成纖維在生產(chǎn)中涉及化學反應工程問題,其中流體流動和傳熱是生產(chǎn)中主要考慮的因素。Thedyeingofafiberisamass-transferproblem.纖維的染色是傳質(zhì)問題。Pulpandpapermanufacturesinvolveconsiderationsoffluidflowandheattransfer.紙漿和紙張生產(chǎn)涉及到流體流動和傳熱問題。Whilethescaleandmaterialsaredifferent,theseagainarefoundinmoderncontinuousproductionoffoodstuff.雖然規(guī)模和材料是不同的,但這些問題在食品的現(xiàn)代連續(xù)生產(chǎn)中又能夠被發(fā)現(xiàn)。Thepharmaceuticalsindustrypresentschemicalengineeringproblems,thesolutionsofwhichhavebeenessentialtotheavailabilityofmoderndrugs.制藥行業(yè)也呈現(xiàn)了化學工程問題,這些問題的解決方案對于現(xiàn)代藥物的可用性是必要的。Thenuclearindustrymakessimilardemandsonthechemicalengineer,particularlyforfuelmanufactureandreprocessing.核工業(yè)對化學工程師提出了相似的要求,特別是對燃料的生產(chǎn)和再處理。Chemic