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1TypesofPneumaticConveyingSystems气力输送系统的种类1INTRODUCTION导言Pneumaticconveyingsystemsarebasicallyquitesimpleandareeminentlysuitableforthetransportofpowderedandgranularmaterialsinfactory,siteandplantsituations.Thesystemrequirementsareasourceofcompressedgas,usuallyair,afeeddevice,aconveyingpipelineandareceivertodisengagetheconveyedmaterialandcarriergas.Thesystemistotallyenclosed,andifitisrequired,thesystemcanoperateentirelywithoutmovingpartscomingintocontactwiththeconveyedmaterial.气力输送系统组成简单，非常适合工厂、工地的粉体和颗粒料的输送。系统要求有一个通常是空气压缩气体源、一个喂料设备、输送管道和一个分离输送物料和输送气体接收器。该系统是完全封闭的，必要情况下，该系统可以完全没有运动部件接触到输送物料。High,lowornegativepressurescanbeusedtoconveymaterials.Forhygroscopicmaterialsdryaircanbeused,andforpotentiallyexplosivematerialsaninertgassuchasnitrogencanbeemployed.Aparticularadvantageisthatmaterialscanbefedintoreceptionvesselsmaintainedatahighpressureifrequired.可以使用高压、低压或负压来输送物料。输送易吸水受潮物料时要采用干燥的空气，输送易爆性物料可使用惰性气体如氮气。有需要的时候，物料也可以被输送到一个有较高压力的接受容器中。1.1SystemFlexibility系统灵活性Withasuitablechoiceandarrangementofequipment,materialscanbeconveyedfromahopperorsiloinonelocationtoanotherlocationsomedistanceaway.Considerableflexibilityinbothplantlayoutandoperationarepossible,suchthatmultiplepointfeedingcanbemadeintoacommonline,andasinglelinecanbedischargedintoanumberofreceivinghoppers.Withvacuumsystems,materialscanbepickedupfromopenstorageorstockpiles,andtheyareidealforclearingdustaccumulationsandspillages.Pipelinescanrunhorizontally,aswellasverticallyupanddown,andwithbendsinthepipelineanycombinationoforientationscanbeaccommodatedinasinglepipelinerun.Materialflowratescanbecontrolledeasilyandmonitoredtocontinuouslycheckinputandoutput,andmostsystemscanbearrangedforcompletelyautomaticoperation.使用合适的的设备，物料可以从一个料斗、料仓输送到远处的另一个料仓。布置灵活，操作方便，例如，可以多点喂料进一条管道，输送到多个料仓。真空吸料系统可以从敞开的存放点吸料并输送，并可以减少粉尘泄漏。输送管道可方便的水平或垂直布置。管道可以向上、向下甚至向任何方向弯曲。可方便地监测物料的进料量和出料量，并对物料输送量进行控制，在大多数的系统中这些操作都是自动进行。Pneumaticconveyingsystemsareparticularlyversatile.Averywiderangeofmaterialscanbehandledandtheyaretotallyenclosedbythesystemandpipeline.Thismeansthatpotentiallyhazardousmaterialscanbeconveyedquitesafely.ThereisminimalriskofdustgenerationandsothesesystemsgenerallymeettherequirementsofanylocalHealthandSafetylegislationwithlittleornodifficulty.气力输送系统适应性强。很大一部分物料都可以在密闭的系统和管道中进行输送。这意味着有潜在危险的物料相当安全的运送，将粉尘泄漏的危险降到最低限度，这些系统一般都满足任何地方卫生和安全方面的要求。Pneumaticconveyingplantstakeuplittlefloorspaceandthepipelinecanbeeasilyroutedupwalls,acrossroofsorevenundergroundtoavoidanyexistingequipmentorstructures.Pipebendsintheconveyinglineprovidethisflexibility,buttheywilladdtotheoverallresistanceofthepipeline.Bendscanalsoaddtoproblemsofparticledegradationiftheconveyedmaterialisfriable,andsufferfromerosivewearifthematerialisabrasive.气力输送系统占地小，管道可方便的沿墙壁，屋顶布置，甚至整个的穿行在地下，以避开任何现有设备或建筑物。管道通过弯曲转向提供这种灵活性，但这将增加管道总的阻力。易碎物料也将因为弯头的增加，产生更多破碎而降级。并且磨削性物料会在弯头处产生冲蚀磨损。1.2IndustriesandMaterials工业和物料Awidevarietyofmaterialsarehandledinpowderedandgranularform,andalargenumberofdifferentindustrieshaveprocessesthatinvolvetheirtransferandstorage.Someoftheindustriesinwhichbulkmaterialsareconveyedincludeagriculture,mining,chemical,Pharmaceuticals,paintmanufacture,andmetalrefiningandprocessing.Inagricultureverylargetonnagesofharvestedmaterialssuchasgrainandricearehandled,aswellasprocessedmaterialssuchasanimalfeedpellets.Fertilizersrepresentalargealliedindustrywithawidevarietyofmaterials.大量不同行业都涉及以粉体和颗粒料的形式存在的多种物料的运送和存储。一些行业，包括农业、采矿、化工、制药、油漆制造、金属冶炼和处理等，其中大部分原料或产品为散料。在农业方面有非常大吨位的收获材料，如谷物和大米的处理，以及动物颗粒饲料的处理。化肥工业中更有各种各样的物料。Avastrangeoffoodproductsfromflourtosugarandteatocoffeeareconveyedpneumaticallyinnumerousmanufacturingprocesses.Confectioneryisanindustryinwhichmanyofthesematerialsarehandled.Intheoilindustryfinepowderssuchasbarite,cementandbentoniteareusedfordrillingpurposes.Inminingandquarrying,lumpcoalandcrushedoresandmineralsareconveyed.Pulverizedcoalandasharebothhandledinverylargequantitiesinthermalpowerplantsforthegenerationofelectricity.食品行业，食糖、面粉，咖啡，茶等物料的转运需要气力输送。在石油精炼工业中，如重晶石粉，水泥，膨润土等粉体用于钻井。采矿业中，块煤和粉碎矿石和矿物需要运送。Inthechemicalindustriesmaterialsincludesodaash,polyethylene,PVCandpolypropyleneinawidevarietyofformsfromfinepowderstopellets.Sandisusedinfoundriesandglassmanufacture,andcementandaluminaareothermaterialsthatareconveyedpneumaticallyinlargetonnagesinanumberofdifferentindustries.热电厂产生的大量煤粉灰需要运送。化学工业的材料包括纯碱，聚乙烯，聚氯乙烯和聚丙烯等粉体和颗粒料。铸造与玻璃制造行业，需要用到砂、水泥、氧化铝及其他材料。以上这些都是气力输送在不同行业中的应用。1.3ModeofConveying输送方式Muchconfusionexistsoverhowmaterialsareconveyedthroughapipelineandtotheterminologygiventothemodeofflow.Firstitmustberecognizedthatmaterialscaneitherbeconveyedinbatchesthroughapipeline,ortheycanbeconveyedonacontinuousbasis,24hoursadayifnecessary.Inbatchconveyingthematerialmaybeconveyedasasingleplugifthebatchsizeisrelativelysmall.关于物料在管道中输送的流动模式的描述很混乱。首先必须承认，物料可以分批次的间歇输送，必要时也可以一天24小时连续不断的输送。分批输送物料时，如果一次输送的物料量较少，可以以一个料栓的形式进行输送。1.3.1DilutePhase稀相Forcontinuousconveying,andbatchconveyingifthebatchsizeislarge,twomodesofconveyingarerecognized.Ifthematerialisconveyedinsuspensionintheairthroughthepipelineitisreferredtoasdilutephaseconveying.I