静电学的基本原理课件

StaticElectricity

-BasicPrinciples–

静电学的基本原理HazardTriangle火三角Fuel可燃物O2(air)助燃物氧气（空气）IgnitionSource引燃源ExamplesofEffectiveIgnitionSources引燃源范例火，火焰，阴燃物质热表面静电（火花放电）机械火花静电（刷形放电）电火花Howdoesanelectrostaticdischargeoccur?

静电是如何产生的？Ignition引燃Ignition引燃ChargeSeparation电荷分离ChargeAccumulationPlantunits电荷积聚于生产设备上ChargeAccumulationProducts电荷积聚于产品上ChargeDissipation电荷消散ChargeDissipation电荷消散Discharge放电Discharge放电Examples:ChargeSeparation电荷分离的范例AccumulationofchargesOnelectricallynon-conductivesurfaces电荷积聚在与地面绝缘的导电物体的表面Examples:ChargeAccumulationII电荷聚集的范例SafetyDataneededforariskassessment

风险分析的安全数据MinimumIgnitionEnergy;(MIE)最低引燃能量ParticleSize(Powder)粒径（粉尘）Conductivityoftheproduct物料的导电性Amountofproductandflowspeed物料量和流速Conductivityofthepackagingmaterial包装材料的导电性TypesofElectrostaticDischarges静电释放的形式Sparkdischarge火花放电

Brushdischarge刷形放电PropagatingBrushDischarge传播形刷形放电ConicalPileDischarge锥形放电

And??????等等Lighting

雷电IgnitionSources着火源IncentivityforBrush

discharge刷形放电MIE<3mJConicalpiledischarge锥形放电MIE<1J(D

=

3m)Sparkdischarge火花放电MIE<1JPropagatingBrushdischarge传播形刷形放电MIE<10JTypesofElectrostaticDischarges静电放电的类型Sparkdischarge火花放电Separationofchargesandelectrostaticcharge分离过程和荷电Totaldischarge电荷完全消散Gradeofdischarge(conductiveobject)

放电等级（两个导电物体距离小于击穿强度时）BrushDischarge刷形放电Separationofchargesandelectrostaticcharge分离过程和荷电PartialDischarge局部有限的电荷消散Gradeofdischarge(nonconductiveobject)

放电的等级（非导电体）Sparkdischarge火花放电personinsulatedfromgroundbyshoes人由于穿着绝缘鞋而与地面绝缘pipeelbowisolatedbyseals管道弯头由于密封材料而绝缘ChargedObject放电体CapacityC电容CPotential电位EnergyW能量[pf][kV][mJ]Flange法兰10100,5Smallcontainer50liter容器50升50-10082-3Metaldrum200-500liter金属桶50-3002010–60Person人100-200127–15Sparkdischarges–Energy

火花放电-能量典型值AvoidanceofSparkDischarges避免火花放电groundingallconductivepartsandproducts(shoes/pipeelbow)所有导电部分及物料（鞋/管道弯道）接地AvoidanceofSparkDischarges避免火花放电ExamplesofBrushDischargesinPractice

生产实践中刷形放电的范例Brushdischargesoccurwhenaconductive,groundedandcurvedobject(electrodewithradiusbetween5-50mm)isexposedtoahighelectricfield.当曲率半径为5-50mm内的的接地、导电的物体（电极）受强电场作用时，就会产生刷形放电throughchargedbulkmaterial通过荷电的散装物料throughchargeddustcloud通过荷电的粉尘云Dischargeofasolidmaterialoutofanon-conductiveplasticbag

放空塑料袋（非导电体）中的固体物料BrushDischarge–ExamplesI刷形放电范例ILoweringofaconductivegroundedsamplingcanorlevelprobeintoavesselwithanon-conductiveliquid(e.g.Toluene)将接地的导电的取样器下插取样或将液位计伸入到非导电液体中去（如甲苯）Approachofaconductiveelectrodesuchasatoolorfingertiptoahighlychargedinsulatedsurface(e.g.FIBC)导电电极如工具或人的指尖接近高荷电的绝缘体表面（如传送液体或粉尘的塑料管塑料袋传送带等）BrushDischarge–Examplescontd.刷形放电范例续Removalofanon-conductiveplasticfoil移开绝缘的塑料膜AvoidanceofBrushDischarges避免刷形放电useofconductive,groundedcontainers(noplasticbags,noplasticcontainers)通过使用导电的接地的包装容器（非塑料袋，非塑料容器）以避免刷形放电Transfer-pipe

withisolatingcoating在具有内层绝缘涂料的管道中Dustcollectorwithisolatingcoating在具有内层绝缘涂料的旋风分离器中Example:

Propagatingbrushdischarges

传播形刷形放电范例PropagatingBrushDischargesinPractice生产实践中传播形刷形放电的范例inpipelinewithinsulatinginnercoating在具有内层绝缘涂料的管道中industseparatorwithinsulatinginnercoating在具有内层绝缘涂料的旋风分离器中onhighspeed,insulatingconveyorbelt在绝缘的输送带上AvoidanceofPropagatingBrushDischarges如何避免传播形刷形放电groundingofallconductivepartsandnoinsulatinginnercoating.所有导电部分接地，内层无绝缘涂层groundingofallconductivepartsanduseofaninnercoatingwith<4kVbreakdownvoltage.所有导电部分接地，内层涂料的击穿电压小于４ＫＶnomaterialofhighdielectricstrength,nobreakdownvoltage>4kV.采用低介电强度的材料，击穿电压小于４ＫＶ的绝缘层ExamplesofConicalPileDischargesinPractice生产实践中锥形放电的范例Fillingoflargesilosandcontainerswithhighlynon-conductivegranules(insulatingbulkmaterials)e.g.,pneumaticfillingofpolymers.

Isolateddischarges atabulkedmaterial surface.将高绝缘的散装物料（绝缘的散装物料），加入到大料仓和容器,比如如气动方式将聚合体加到孤立的的散装料表面时曾观察到在散装物料表面发生的绝缘放电Avoidanceofhighdangerouselectrostaticcharges

生产实践中避免高电荷范例高流速抗静电添加剂非导电低流速导电非导电高流速Handlingofflammableliquids:

易燃液体操作AvoidanceofincendivedischargesIExclusiveusageofConductiveandGroundequipment只可使用导电的容器并接地AvoidanceofincendivedischargesIIHandlingofflammabledusts:易燃粉尘的操作规程Groundallconductiveequipment;smallplastic-container(i.e.bags)arepermittedaslongastherearenoflammableGasesnorflammablevapourspresent.将所用的导电部分接地，在无易燃液体气体和蒸气存在时，可容许使用小塑料容器（如包装袋Groundmetalflanges