密封基础知识(基本结构).ppt

1、1,Basic Mechanical Seals密封基础知识,JC Tianjin Training,2,rotating seal unit,two flat sliding surfaces, which maintain a close running clearance while separated by a fluid film 两个光滑平面之间维持着一个由流体膜隔开的微小间隙,stationary seal unit,What is a mechanical seal?什么是机械密封？,Desired Features of a Seal机械密封必须有的特征,Long-life

2、很长的寿命 Easy maintenance 容易检修 Low cost 低成本,Small axial clearance 小的轴向间隙 Self adjusting 自调节,Shaft Movement 轴的运动,4,Basic Mechanical Seal基础机械密封,Loose ring set screwed to the shaft 把一个有间隙的环用顶丝固定在轴上,1,5,Basic Mechanical Seal基础机械密封,O-ring prevents leakage through the bore,2,6,Basic Mechanical Seal基础机械密封,Spr

3、ing ensures automatic adjustment 弹簧确保自动调整,3,7,Basic Mechanical Seal基础机械密封,4,8,Basic Mechanical Seal基础机械密封,5,9,Basic Mechanical Seal基础机械密封,Gasket or O-ring,SEAT,Recirculation for cooling,SPRING OR SPRING FORCE,O-Ring O型圈,Shaft轴,Mating Ring 配合环,Primary Ring补偿环,Snap Ring卡环,Anti-X Ring 挡环,O-Ring O型圈,Dis

4、k推环,Springs弹簧,Retainer传动套,Set Screw定位螺丝,An Example of a Complete Seal一个完整密封的例子,Simply put, a mechanical seal is:简单的说,机械密封就是:,1.A wearable, stationary, primary sealing element 一个耐磨,静止的密封件 2. A wearable, rotating, primary sealing element 一个耐磨,旋转的密封件 3. A secondary sealing element 二次密封 4. A mechanical

5、loading device to press primary sealing elements 1 and 2 against one another, and 使件1和件2相互贴合的机械装置 5. Auxiliary components to complete seal 使密封更加完善的辅助件,12,不像一个机械密封而更像一个限制装置,需要泄漏否则将会灼伤. 会磨损轴或轴套 高功耗用来克服磨擦 产品损失 需要大量的水 安装,维修和盘根调整需要停车时间 泄漏导致设备破坏和摧毁,不可见泄漏、机械密封和盘根之间的泄漏率在1到100或者更好 证明机械密封的寿命可达8到10年毫无故障 无产品损失,

6、节省水和能量可以节省成本 安装后维修很少 密封有潜在危害的物质时机械密封可以提供更好的安全性,Gland Packing v. Mechanical Seals盘根和机械密封,13,SPRING FORCE FLUID PRESSURE,fluid film (3 - 5 microns),a thin film of liquid forms the primary (dynamic) seal between the rotating and stationary elements在旋转件和静止件之间形成很薄的液膜,FILM REACTION,Primary Seal 主密封,14,Fac

7、es lapped flat to within 1 - 3 light bands.,Primary Seal Film Thickness主密封膜厚度,15,Primary Seal Film Thickness主密封膜厚度,Fluid film thickness is very important too thin - wear, causing early seal failure too thick - visible leakage Must be: present - beware dry running谨防干运转 Stable稳定 谨防磨损征兆 clean - beware

8、abrasive wear symptoms reasonable viscosity合理的黏度 temperature controlled受控的温度 acceptable pressure允许的压力,16,Primary Seal Face Flatness主密封平面,If faces not flat, contact generates heat Excessive wear - short life,1 light band = 0.0000116 inch or 0.0003 mm,Lubricant 润滑剂,Separation分离面,Magnified Surface A 放大

9、面,Magnified Surface B 放大面,Heat 热量,The Sealing Interface 密封面,Lubrication Purpose: 润滑目的 Separate surfaces 分离两个面 Prevent contact of high surface points 防止出现面接触 Reduce friction/heat generation 减少摩擦/生热,Process Fluid Acts as Lubricant Between Faces流体在两个面之间充当润滑剂的过程,Gland 密封端盖,Pump Housing 泵腔,Process Fluid

10、工艺流体,Invisible Leakage: 不可见泄漏 Fluid Evaporates Upon Reaching Atmosphere 微量的泄漏在大气侧蒸发,Primary Ring 补偿环,Mating Ring 配合环,Gland 密封端盖,Pump Housing 泵腔,No Fluid Or Dry Running 没有流体或者干运转,Primary Ring 补偿环,Mating Ring 配合环,Without Lubrication, Faces Run Dry And Overheat没有润滑干运转导致过热,20,常用动环材料,Face (Primary Ring)

11、Materials 动环材料 Carbon-graphite 碳石墨类 resin impregnated 树脂浸渍 （171） antimony impregnated 金属锑浸渍 （218） Carbon converted to Silicon Carbide 硅化石墨（121） CVR 化学汽相反应硅化石墨 CVD 化学汽相沉积硅化石墨 Solid Silicon Carbide 碳化硅 Sintered silicon carbide 无压烧结碳化硅 (277) Reaction silicon carbide 反应烧结碳化硅（088） Sintered silicon carbid

12、e with controlled porosity 微孔碳化硅 （584） Tungsten Carbide 碳化钨 Cobalt bonded 钴基碳化钨（025） Nickel bonded 镍基碳化钨（005）,21,常用静环材料,Seat (Mating Ring-Narrow) Materials 静环材料 Ceramic 陶瓷 99.7% Aluminium Oxide 氧化铝 (059) Solid Silicon Carbide 碳化硅 Sintered silicon carbide 无压烧结碳化硅 (277) Reaction silicon carbide 反应烧结碳化

13、硅（088） Sintered silicon carbide with controlled porosity 微孔碳化硅 （584） Tungsten Carbide 碳化钨 Cobalt bonded 钴基碳化钨（025） Nickel bonded 镍基碳化钨（005）,22,Secondary Seal 二次密封,Three basic forms 三种基本形式 o-rings o型圈 Wedges 楔形环 Bellows 波纹管 Elastomer 橡胶的 Metal 金属的 Formed 成型的 edge welded 焊接的 PTFE,Two groups Pusher推进式

14、Sliding滑移 o-rings wedges Non-pusher 非推进式 Bellows风箱,Teflon Bellows 聚四氟乙烯波纹管,Elastomeric Bellows 橡胶波纹管,Half Convolution 半波,Welded Metal Bellows 焊接金属波纹管,V Rings V型圈,U Cup 杯型,Wedge 楔形,Encapsulated O Ring 包覆 O型圈,O Ring O型圈,Secondary Sealing Elements二次密封,Pusher 推进式,Non-Pusher 非推进式,O-ring secondary seal mu

15、st slide along shaft as seal face wears O型圈二次密封在密封面磨损的时候必须能够沿轴滑动,Bellows secondary seal expands to accommodate face wear. Bellows tail is stationary against shaft. 波纹管伸长能够补偿密封面磨损,波纹管尾部与轴保持静止,vs.,Pusher vs. Non-Pusher推进式/非推进式,25,Secondary Seal: Pusher二次密封：推进式,As the face moves forward to take up wear

16、, the o-ring moves forward with the face, pushed by the hydraulic and spring pressures,26,Secondary Seal: Pusher二次密封：推进式,Advantages 优点 sudden failure very unlikely 几乎不会突发意外事故 higher pressure capability - face not stressed 耐压性能高-应力变形小 wide choice of materials for all components 所有成分的材料选择广泛 field repa

17、irable可修复的 Disadvantages 缺点 hang-up (not likely where o-ring is well isolated) 挂起 permanent set / pressure problems (cause hang-up) 长久放置/压力问题（导致挂起） excellent shaft surface finish required要求轴的表面光滑 maximum temperature +260C 最高温度+260C,27,Pusher Seal: Hang-up推进式密封：挂起,Product leakage solidifies / crystal

18、lises / polymerises,Prevents o-ring pushing forward - leakage increases 阻止O形圈迅速的推进-泄漏增加,An external quench will prevent hang-up 外部的冲洗可防止挂起,28,Secondary Seal: O-Ring二次密封：O型圈,Type 8B1,29,Secondary Seal: Wedge二次密封：楔形环,30,Secondary Seal: Non-Pusher二次密封：非推进式,Bellows flexes to take up wear, misalignment a

19、nd axial play,Fine machined shaft surface required精掣轴表面 Do not use a good lubricant - never use silicon grease,31,Secondary Seal: Bellows二次密封：波纹管,32,Secondary Seal: Metal Bellows二次密封：金属波纹管,static o-ring 静止o型圈,33,Type 10T,Type 10R,Secondary Seal: PTFE Bellows二次密封：PTFE波纹管,Tertiary Seal 三次密封,35,Tertiar

20、y Seal 三次密封,Prevents leakage round mating ring 防止静环周围的泄漏 Sometimes also prevents mating ring rotation 有时也防止静环旋转,36,Tertiary Seal 三次密封,Four basic types 四种基本的形式 O-rings O型圈 Elastomers 橡胶 Seat Rings (square or rectangular section) PTFE graphite Cup Rings elastomers Gaskets or Flat Joints PTFE compresse

21、d fibre非石棉的压缩纤维,Tertiary Seal: O-ring三次密封：O型环,Tertiary Seal: O-ring三次密封：O型环,Tertiary Seal: O-ring三次密封：O型环,40,Tertiary Seal: Seat Ring三次密封：静环,Tertiary Seal: Cup Rubber三次密封：,Spring Design Features 弹簧设计特点,Springs 弹簧 Provide The Initial Closing Force 提供初始闭合力 Are Very Important At Low Pressures 低压下很重要 Ar

22、e Not So Important At High Pressures 高压下不重要,Design Features 设计特点,Springs 弹簧 Single 单弹簧 Multiple 多弹簧 Bellows 波纹管 Wave 波形,Design Features 设计特点,Springs 弹簧 High Speed Seals Use Stationary Springs (5000 ft/min Typical Break Point) 高速机械密封使用静止弹簧 (5000ft/min 典型的分界点),Design Features 设计特点,Springs 弹簧 Corrosion

23、 腐蚀 Clogging 堵塞 Uniformity Of Load 负荷一致 Inventory 批量,Drive Mechanism 驱动机械 Must Transmit Torque 必须能够传递转矩 Must Allow Axial Movement (Primary Ring) 必须能够使动环轴向运动,Types of Drive Mechanisms 驱动机械的类型,Pin Drive 销驱动,Dent Drive 凹窝驱动,Slot and Ear 槽和支耳,Spring Drive弹簧驱动,Set Screw Drive 定位螺丝驱动,Snap Ring Drive 卡环驱动,

24、Elastomer Drive 橡胶驱动,Key Drive 键驱动,Types of Drive Mechanisms 驱动机械的类型,48,Seal Materials 密封材料,Material Considerations 材料需要考虑 Temperature 温度 Thermal Expansion 热膨胀 Thermal Conductivity 导热性 Chemical Resistance化学稳定性 Wear 磨损性 Flexibility 弹性 Manufacturability 制造能力 Cost 成本 Availability 实用性,49,Primary Seal Materials主密封材料,Face (Primary Ring-Narrow) Materials 窄环材料 Carbon-graphite 炭-石墨 resin impregnated 浸渍树脂 antimony impregnated 浸渍金属锑 Carbon converted to Silicon Carbide 硅化石墨,50,Primary Seal Materials主密封材料,Carbon converted to Silicon Carbide,51,Solid Silicon Carbi