Boiler Feed Pump End Mechanical Seal Applications

Boiler feed water pumps are important equipment in thermal power plant,which take on providing eligible deoxidized hot water for boiler,which are the heart of entire flow circle.The shafe end sealing device of feed water pumps goes wrong mostly frequently. The main types of shaft end seals for boiler feed water pump is the mechanical seals. Application, study on the mechanical seal is of the significance for feed water pumps working reliably and technique reconstruct.The main types of shaft end seals for boiler feed water pumps are introduced briefly: paking seal,helical seal,floating-ring seal,mechanical seal,virtues and shortcoming are compared with each other. The mechanical seal show its advantages that leakage amount ia little , power loss is little , performance parameters are high. Along with feed water pumps develop for the high speed, high temperature, high pressure direction, the mechanical seal will replace the other sealing types gradually.Firmly speaking,mechanical seals are the equipments containing at least a pair od end face perpendicular to axis of rotation,which are working in the liquid pressure and the elasticity of compensation organizations as well as the coordination of auxiliaury seals to keep integrating closely and sliding relatively,take effect to present liquid leaking. The paper introduces the basic mechanical seal types for pumps, which work life and performances are decided by wear state. From the sides of leakage amout, abrasion,film pressure attribution,the thesis analyzes the influence of lauder figure of the seal faces on sealing performance .It is most excellantest at present that the seal faces keep radially parallel. Wear state is the key that desides the life and performance of the mechanical seals .The general mechanical seals are in the mixed friction state,by means of analyzing the influencing factors on the friction characteristic like friction coefficient and specialty number,fludic film carraying ratio is used as the criterion that judges the friction phase state. .The temperature of hot water pump feeding medium is high,which result in the high temperature of the shafe sealing bellow. High temprature on the seal face is liable to bring into abrasion,or heat crack ,or fluid film vaporazition,accessorial sealing componets aging etc.The face temperature being keeping on a appropriate level is necessary condition that the mechanical seal works reliably.Research on sealing face temperature is a important question for discussion.The face temprature may be obtained by calculation in theory.but the calculation of temperature field is complex and make a bit difference vice practical measure value ,therefore the measurement is of the imporatance in practice.Cooling and flushing is a efficient measurement which can decrease the temperature of the shaft sealing bellow and remove the thermal value that the sealing ring friction produce. In the condition of hot water ,the flushing have many kinds of plans,for example API plan32.Be combinded with thermodynamic flow in the power plan,it is suitable for feed water pump that concreting water wash the surface of mechanical seal.Thermohydrodynamic mechanical seals belong to non-contract mechanical seals,which will be widly applied because its friction coefficient is smaller,...