逆流冷却器设计详解

1冷却过程COOLINGPROCESS冷却过程是在一定的时间内将产品的温度和水分平衡到标准质量状态的一种热交换过程。Theprocessbalancedtemperatureandhumidityoftheproducttostandardqualitywithinlimitedtime定义/Definition2温度平衡TEMPERATUREEQUILIBRIUM-热通过蒸发过程而变成水蒸汽HEATUSEDFOREVAPORATIONPROCESSTOVAPOR-热通过热的传播过程传递到冷却介质上HEATTRANSFERTOCOOLANT(MOISTAIR)THROUGHTHERMALDIFFUSIONPROCESS3-毛细管作用造成的液体流动LIQUIDMOVEMENTDUETOCAPILLARITY-渗透力造成的液体流动LIQUIDMOVEMENTDUETOOSMOTICFORCE-水份差异造成的液体流动（液体扩散作用）LIQUIDMOVEMENTDUETOMOISTURECONCENTRATIONDIFFERENCE(LIQUIDDIFFUSION)温度平衡TEMPERATUREEQUILIBRIUM4-重力造成的液体流动LIQUIDMOVEMENTDUETOGRAVITY-水份差异造成的蒸汽流动（蒸汽扩散作用）VAPORMOVEMENTDUETOMOISTURECONCENTRATIONDIFFERENCE(VAPORDIFFUSION)-温度差异造成的蒸汽流动（热扩散作用）VAPORMOVEMENTDUETOTEMPERATUREDIFFERENCE(THERMALDIFFUSION)温度平衡TEMPERATUREEQUILIBRIUM5冷却过程CoolingProcess1.蒸发EVAPORATION2.热扩散THERMALDIFFUSION3.机械或化学力造成的液体流动LiquidmovementbyMechanical&ChemicalForce4.机械或化学力造成的蒸汽流动VapormovementbyMechanical&ChemicalForce6颗粒料冷却PELLETCOOLING它是通过蒸发和热扩散过程，使料的温度和环境空气相平衡，从而降低颗粒料温度和水份（粉状料经过蒸汽调质与制粒过程而增加的温度与水份部分）的一种过程。Theprocessofdecreasingtemperatureandmoisturefrompellets(whichincreasebymashconditioningwithsteamandpelletingprocess.)环境空气进入冷却器，在一定的时间内与颗粒料外表面接触，直到颗粒料温度不超过环境温度+5oC以上,颗粒水份不超过12%.bytemperatureandhumiditybalancewithambientairthroughtheevaporationandthermaldiffusionprocess,theambientairisbroughtincontactwiththeoutersurfaceofthepelletsinthecoolerwithinlimiteddurationuntilthepelletTemperatureislessthanorequaltheambienttemperature+5oCandthepelletsmoisturemustnotbeexceed12%.7CoolAirWarmAirVaporVaporWaterHeat温度降低原因有：TemperatureDecreaseby•蒸发(热用于将液体变成蒸汽）Evaporation(heatusedforchangeliquidtovapor)•热扩散(热传递出去)HeatDiffusion(heattransferout)水份降低原因有：MoistureDecreaseby•蒸发(蒸汽脱离)Evaporation(vapormoveout)•运动力(液体脱离)KineticForce(liquidmoveout)颗粒料冷却PELLETCOOLING8颗粒料冷却PELLETCOOLING40°C12%M32°CAmbientTemp.HeatDiffusion32°C11%M32°CAmbientTemp.HeatBalanceSurface14%M9颗粒料冷却特性PELLETCOOLINGCHARACTERISTIC卧式冷却器/CROSSFLOWCOOLERAirFlowProductflowAirInletTempAirOutletTempPelletBeginTempPelletEndTemp10逆流式（或立式）冷却器/COUNTERFLOWCOOLERAirFlowProductflowAirInletTempAirOutletTempPelletBeginTempPelletEndTemp颗粒料冷却特性PELLETCOOLINGCHARACTERISTIC11TemperatureChange25.030.035.040.045.050.055.060.065.0048121620TimeTemperature-C颗粒料冷却曲线图PELLETCOOLINGPROFILEEvaporationStageThermalDiffusionAmbientTemperature30°CRelativeHumidity70%12MoistureChange12.012.513.013.514.014.515.0048121620Time%MoistureEvaporationStageLiquid&VaporMovementAmbientTemperature30°CRelativeHumidity70%颗粒料冷却曲线图PELLETCOOLINGPROFILE13冷却过程影响因素Thefactorseffectedtocoolingprocess.1.颗粒状态Pellets-温度Temperature-水份Moisture-密度Density-大小和形状Size&Shape-油脂喷涂FatCoated142.环境空气AmbientAir-温度Temperature-相对湿度RelativeHumidity-风量Volume-蒸气压力VaporPressure-空气中水份与蒸气浓度Watercontentandvaporcontentintheair3.颗粒料在空气中的流动时间Timethatpelletsmovewithintheair冷却过程影响因素Thefactorseffectedtocoolingprocess.15EVAPORATIONTHERMALDIFFUSIONLIQUID&VAPORMOVEMENTPRODUCTINPRODUCTOUTMOISTAIRINMOISTAIROUT16影响动物消化的因素Animaldigestionfactors1.蒸发Evaporation-颗粒温度Pellettemperature-颗粒湿度Pelletmoisture-油脂喷涂Fatcoating-风量Airvolume-蒸气压力Vaporpressure172.热传递Heattransfer-颗粒温度Pellettemperature-颗粒密度Pelletdensity-颗粒大小与形状Pelletsizeandshape-油脂喷涂Fatcoating-风量Airvolume-空气温度Airtemperature-颗粒停留时间Pelletdwelltime影响动物消化的因素Animaldigestionfactors183.4因机械和化学作用造成的蒸气/液体流动Vapor/liquidmovementbymechanicalandchemicalforce-颗粒水份Pelletmoisture-颗粒密度Pelletdensity-颗粒大小与形状Pelletsizeandshape-风量Airvolume-空气相对湿度Relativehumidityofair-空气蒸发压力Airvaporpressure-空气中水份与蒸气浓度Moistureandvaporaircontent-颗粒停留时间Pelletdwelltime影响动物消化的因素Animaldigestionfactors19冷却过程需要的风量AirVolumeRequiredforCoolingProcess为降低1000KGs.颗粒料温度与水分:进料温度90°C出料温度33°C进料水份15%出料水份12%采用30°C的环境空气冷却器空气出口温度45°CTodecreasetemperatureandmoistureof1000KGs.-pelletsPelletsInletTemp.90°CPelletOutletTemp.33°CPelletsInletMoisture15%PelletOutletMoisture12%Byusingtheambientairat30°COutlettemperaturefromcooler45°C冷却过程空气需要量经验计算Practicalcalculationforfindingairvolumeusesforcoolingprocess20将颗粒水分从15%降低到12%:水分15%意味着颗粒1000KGs.包括水150KGs.和干料850KGs.水分12%意味着颗粒100KGs.由干料88KGs.和水12KGs.组成.故此,如干料有850KGs.水则有12x850/88=116KGs.那么蒸发掉的水就是150-116=34KGs.Todecreasemoisturefrom15%to12%Moisture15%meansthepellets1000KGs.Consistofwater150KGs.anddrycomponent850KGs.Moisture12%meansthepellets100KGs.Consistofdrycomponent88KGs.andwater12KGs.So,Iftherearedrycomponent850KGs.water12x850/88=116KGs.Thenmustbeevaporatedwater150-116=34KGs.冷却过程空气需要量经验计算Practicalcalculationforfindingairvolumeusesforcoolingprocess冷却过程空气体积需要量AirVolumeRequiredforCoolingProcess21冷却过程空气体积需要量AirVolumeforCoolingProcess自颗粒传递的热:/Heattransferfrompellets:由:Q=mc(t2-t1)Q=1000*1.8*(33-90)=-102,600KJ.将1KG.水蒸发变成蒸气需要的热量=2,360KJ.Heatusedtoevaporatewater1KG.tovapor故;蒸发34KGs.水需要的热量So;Heatusedtoevaporatewater34KGs..=34*2,360KJ.=80,240KJ颗粒必须传递的热量Heatmustbetransferredfrompellets=80,240-102,600=22,360KJ.22空气体积需要量:/Airvolumerequired:由Q=mc(t2-t1)故;22,360=m*1*(45-30)空气重量需要量(m)./Airweightrequired(m)=22,360/15=1,490KGs单位空气体积重量/Weightofairbyvolume=1.2KGs./1m3故;空气体积需要量/So;Airvolumerequired=1,490/1.2=1,240m3估计的空气体积需要量1,200m3/ton-颗粒Estimatedairvolumerequire1,200m3/ton-