The Study Of Thermal-mechanical Performance And End Face Modification For Double Mechanical Seal In Emulsion Equipment

Emulsion equipments most adopt double mechanical seals,for conveying medium is high temperature and viscosity,easily flammable,explosive and volatile,contains small particles.But the seals often lead to premature failure owing to variational operating environment,inadequate auxiliary system matching and other factors in practice.This paper was subsidized by the national natural science fund project(NO.51279067) and the aviation science foundation project(NO.201328R3001).In fact, double mechanical seals applied to emulsion equipments is easy to wear on end face, which leads to failure.Based on the analysis of failure mechanism, taking the double mechanical seal applied to AR201 dynamic mixer as the research object, the influence of parameters of auxiliary flushing system on the thermal characteristics and thermal-mechanical deformation characteristics of seal rings,modification of seal face and fluid-structure thermal-mechanical coupled research were studied in the paper,to provide theoretical reference for design and application of the seal.And main research work and conclusions are as follows:Based on the theory and analysis method of mechanical seal failure, failure cases of emulsion equipment double mechanical seals were analysed to seek the main reasons of seal failure. Study shows that evaporation of the liquid film under high temperature and bad thermal-mechanical characteristics of the seal face in complex working conditions are the main factors of dry friction and wear failure.Double mechanical seal applied to the emulsion AR201 dynamic mixer was taken as the research object,heat-transfer and thermal-mechanical deformation calculation model are established. The influence law of auxiliary flushing system parameters on the seal temperature distribution and thermal-mechanical deformation were studied by simulating analysis.Flushing parameter control scheme was put forward for the improvement of sealing performance.According to the operation of the sealing environment and replacement lubrication of end face with flushing fluid in emulsion double mechanical seal, spiral groove was modified on main seal face into a non-contact style. Thermal characteristic of the retrofit of the primary seal was analysed by simulation,and comparing the sealing performance before with after modification.Research showed that,sealing performance is significantly increased after modification,end face temperature rise and friction torque decrease obviously,demand for flushing system parameters is obviously decreased and energy saving effect is remarkable.Two-way fluid-structure thermal-mechanical coupled model of liquid film and sealing ring was established on ANSYS Workbench platform,the temperature distribution and the change rule of the maximum deformation of the seal face after modification under different flushing fluid parameters were studied. Studies show that the thermal-mechanical deformation increases with the flushing temperature and pressure, and the effect of flushing pressure is more significant than that of flushing temperature on the thermal-mechanical deformation;Comparing to the results of normal thermal characteristics,average thickness of liquid film and the leakage of two-way fluid-structure interaction reduce by 3.7% and 10.2% respectively, the highest temperature of end face and friction torque increases by 11.4% and 16.7%.