造纸专业英语5.ppt

Lesson14Beatingandrefining Thetermsbeatingandrefiningareoftenusedinterchangeably Moreprecisely beatingreferstothemechanicalactionofrotatingbarsopposingastationarybedplateonacirculatingfibersuspensionwheretheindividualfibersareorientedperpendiculartothebars ThisbatchoperationisexemplifiedinthetraditionalHollanderbeaterwhichisstillusedinsomeolderpapermills especiallyforhandlingsuchdifficultfurnishersasjute hemp flaxandcotton refine精炼 精制rotatingbar旋转飞刀jute黄麻bedplate底板 底座hemp 植 大麻 纤维 batch一批 一次投料量flax亚麻 Lesson14Beatingandrefining Refiningreferstothemechanicalactioncarriedoutincontinuousconicalordisk typerefinerswherethefibersmoveparalleltothecrossings Inallcases theobjectiveistodevelopormodifythepulpfibersinanoptimalmannerforthedemandsoftheparticularpapermakingfurnish conical锥形的crossing交叉点 Lesson14Beatingandrefining Duringrefining bothmechanicalandhydraulicforcesareemployedtoalterthefibercharacteristics Shearstressesareimposedonthefibersbytherolling twisting andtensionalactionsoccurringbetweenthebarsandthegroovesandchannelsoftherefiner Normalstressesareimposedbythebending crushingandpulling pushingactiononthefiberclumpscaughtbetweenthebar to barsurfaces hydraulic水力的 水压的hydrant消防水龙头roll滚压groove沟纹 凹槽clump丛 块 Lesson14Beatingandrefining Theinitialactionistopartiallyremovetheprimary P wall RemovalofP layerexposesthesecondary S wallandallowswatertobeabsorbedintothemolecularstructure Theconsequentlooseningoftheinternalstructure internalfibrillation promotesfiberswellingandrendersthefibersoftandflexible fibrillation细纤维化 Lesson14Beatingandrefining Thefurtheractionofexternalfibrillationinvolveslooseningofthefibrilsandraisingofthefibermicrofibrilsonthesurfaceofthefibers resultinginaverylargeincreaseinsurfaceareaforthebeatenfibers Asthefibersbecomemoreflexible thecellwallscollapseintolumens thuscreatingribbon likeelementsofgreatconformability collapse倒塌 崩溃conformability一致性 Lesson14Beatingandrefining Fibershorteningorcuttingalwaysoccurstosomeextentduringrefining mainlyduetotheshearingactionofthebarcrossings Refiningalsoproducesfinesconsistingoffragmentsofbrokenfibersandparticlesremovedfromfiberwalls Oneobviouseffectofrefiningisthedramaticchangeinthedrainageordewateringpropertiesofthepulp Pulpdrainabilityisrapidlyreducedastherefiningproceeds mainlyduetotheincreasedconcentrationoffines Lesson14Beatingandrefining Twofactorsareofprimaryimportanceinanalyzingrefinerperformance theamountofeffectiveenergyappliedperunitweightofpulp netspecificenergy andtherateatwhichtheenergyisapplied refiningintensity Thefirstfactorcanbepreciselymeasured Thespecificedgeloadiswidelyappliedtoevaluatehowintensivelythefibersarehit whichiscalculatedbydividingtherateofnetenergyapplication netpower bythetotallengthofbaredgescontactingthestockperunittime specificedgeload比边缘负载 Lesson14Beatingandrefining Twomajortypesofcontinuousrefinersusedforstockpreparationarediscrefinersandconicalrefiners Theconicalrefinerscanbefurtherdifferentiatedintolow angletypes Jordans andhigh angletypes Claflins Inconicalrefiners therotatingplug rotor anditshousing stator arefittedwithmetalbarsorientedlengthwise Thefiberflowparalleltothebars Thepositionoftheplugdeterminestheclearanceofthebarsandcontrolstheamountofworkdoneonthefibersforaconstantstockthroughout discrefiner圆盘式精磨机conicalrefiner锥形精磨机rotor转子housing外壳 外套stator定子clearance间隔 距离 Lesson14Beatingandrefining Discrefinersaremorerecentdevelopmentandoffersignificantadvantageoverconicalrefiners Therearethreebasictypesofdesigns rotatingopposingstationarydisc twoopposingrotatingdiscs androtatingdouble sideddiscbetweentwostationarydiscs Forthelastdesign thestockflowcanfolloweitheraparallelarrangement duoflow oraseriesarrangement monoflow parallelarrangement并联装置seriesarrangement串联装置 Lesson14Beatingandrefining Typically tearstrengthalwaysdecreaseswithrefiningduetothestrengthattritionofindividualfibers otherstrengthparameterssuchasburst tensile foldingenduranceincreasesduetoimprovedfiber to fiberbonding Thepaperstockbecomeslowertodrainandresultantsheetsbecomedenserwithreducedporosity loweropacity anddecreaseddimensionalstability tearstrength撕裂强度attrition摩擦burst耐破度foldingendurance耐折度dimensional尺寸的porosity透气度opacity不透明度 Lesson15Nonfibrousadditivesandwet endchemistry Awiderangeofchemicalsisutilizedinthepapermakingstockfurnishtoimpartorenhancespecificsheetpropertiesortoserveothernecessarypurposes Functionaladditivessuchasalum internalsizingagents mineralfillers starch anddyesareusedtoimpartcertainqualitiestothepaperproductandmustberetainedonthesheettobeeffective alum明矾 Lesson15Nonfibrousadditivesandwet endchemistry Controladditivessuchasdrainageaids defoamers retentionaids pitchdispersants biocides andcorrosioninhibitorsareaddedasrequiredtoimprovethepapermakingprocess butdonotdirectlyaffecttheproductandarenotnecessaryretainedontheproduct pitch树脂dispersant分散剂biocide杀虫剂 Lesson15Nonfibrousadditivesandwet endchemistry Manyadditiveshaveseveraleffectsatthesametime forexample alumisrequiredforrosinsizingunderacidconditionsbutalsoservesasadrainageandretentionaid Theorderofadditionmustbetakenintoaccounttopreventinteractionatthewrongtimeandenhanceretentioninthepapersheet Fortheeconomicperspectiveonthechemicalandmineralcontributiontopapermaking anaverage10 ofthecostofmakingpapercanbeattributedtochemicals rosin松香resin树脂 Lesson15Nonfibrousadditivesandwet endchemistry Wetendchemistrydealswithalltheinteractionsbetweenfurnishmaterialsandthechemical physicalprocessoccurringatthewetendofthepapermachine Themajorinteractionsatthemolecularandcolloidallevelaresurfacecharge flocculation coagulation hydrolysis time dependentchemicalreactionsandmicrobiologicalactivity Theseinteractionsarefundamentaltothepapermakingprocess colloid胶体colloidal胶体的charge电荷 充电flocculation絮凝flocculant絮凝剂coagulation凝结coagulant凝结剂 Lesson15Nonfibrousadditivesandwet endchemistry Therearethreemajorgroupsinvolvedinwet endchemistry solid colloidsandsolubles Mostattentionsisfocusedonthesolidsandtheirretention Somecolloidalmaterials referredascationicdemand anionictrash orinterferingsubstances areintroducedfromeitherthecarryoverofpulpingmillandbleachingplant broke orprocesswaterandwillinterferewiththeactionofcationicchemicaladditives carry over携带broke损纸 Lesson15Nonfibrousadditivesandwet endchemistry Thezetapotentialisacolloidaleffecthavingtodowithchargedistributionsonthesurfaceofsuspendedparticles whichisthechargedensityonthesurfaceofcolloidsandsuspendedparticles Itvariesfromabout 50mVto 50mV Retentionisoftenatamaximumwhenthechargedensityisnearz