The Analysis On The Characteristic Of Coupling Of High Temperature Corrosion And Wear Acting On Supercritical Boiler's Water Wall

Supercritical boiler has pretty high efficiency because of high parameter,which causes high temperature corrosion.The coupling of high temperature corrosion and ash particle erosion can do great harm to boilers.The characteristic of coupling depends on waterwall's temperature,the concentration of h₂s,the impact velocity and quantity of coal ash particles,etc.In this paper,numerical simulations on a 660MW supercritical tangentially coal-fired boiler were performed based on Ansys Fluent.The average temperature on inner surface of waterwall was gotten by using Fluent programming function which was assigned to wall condition,and the maximum temperature in all grids was showed.The impact massflow value(unit:kg·m^-2·s^-1)on the waterwall in burner area was gotten by using fluent erosion wear model.By using the sample function of fluent and excel data processing function,the maximum velocity and the velocity of particles is gotten.The result indicates that the maximum average temperature is 698K,appearing above the SOFA area,the highest mass concentration of H₂S is 0.24%;the maximum velocity of particles impacting the waterwall in burner area can exceed30m/s with a proportion less than 0.3%,the subject of velocity value is 5-20m/s,and particles with a speed from 20m/s to 25m/s may occupy a considerable proportion?close to 10%?,and nozzle particles'maximum impact on the area facing the burner massflow value is 6kg/?m²·s?.Coupled erosion experiment is conducted with the simulation result.15CrMoVG and SA-213T12 are heated at different temperatures and washed by 0.2%H₂S+99.8%N₂ atmosphere containing coal ash particles with different impact angles and velocities.The result indicates that 90°is the best suited impact angle to study on coupling because of relatively strong coupling corrosion effect and no migration in erosion area.And 15 m/s particle impact can cause the same coupling effect with35m/s.15CrMoG's corrosion products is better at resistance to ash particle erosion.At335 and 435 degrees,15CrMoG and SA-213T12 can get the same coupling corrosion effect.At 535 degrees the ranking is 15CrMoG>SA-213T12.15CrMoG is cheaper,so 15CrMoG is more suitable for water wall.Coupling corrosion effect depends on high temperature corrosion effect,it is recommended to lighten coupling corrosion by lightening high temperature corrosion.