Research On Characteristics Of Iron Oxide Particle Erosion Of A 1000MW Ultra Supercritical Steam Turbine

With the rapid growth of power demand,the rapid development of power industry and the continuous expansion of power grid capacity,steam turbines are developing in the direction of high parameters and large capacity.However,with the increase of initial temperature and pressure of steam in large units,the oxidation process of the inner wall of super-heater and main steam pipeline of boiler intensifies.The oxide films?mainly Fe₃O₄ and Fe₂O₃?which fall off the inner wall of the pipeline are carried into the steam turbine by high temperature and high pressure steam,which erode the stator and rotor blade of the turbine governing stage,and increase the surface roughness of the blade,even produce the notch when the erosion is serious,which causes the unit economy and the security extremely to drop.Therefore,the study of solid particle erosion?SPE?characteristics of ultra-supercritical steam turbines has important guiding significance for the actual operation of power plants.Based on Lagrangian method and solid particle transport model which is effective only for dilute phase flow,the SPE problem of a 1000MW ultra-supercritical steam turbine governing stage blade is studied by using three-dimensional numerical simulation software ANSYS-CFX.The main research contents are as follows:?1?For the problem that the SPE causes stator pressure surface roughness change,the variation of the aerodynamic performance in the governing stage under different roughness is analyzed.The results show that,with the increase of the surface roughness of the stator blade,the velocity coefficient of the nozzle begins to decrease.With the increase of the roughness,the velocity coefficient of the nozzle decreases rapidly at first and then slowly.At the exit section of the nozzle,the total pressure loss coefficient increases with the increase of the roughness.The total efficiency and static efficiency of stage show a downward trend with the increase of blade surface roughness,and the downward trend decreases with the increase of blade surface roughness.With the increase of roughness,the maximum erosion rate density increases,but the erosion location is almost unchanged.?2?For the problem that the stator is severely eroded by solid particles and the trailing edge is notched,the aerodynamic performance of the governing stage under different types of notch is analyzed.The results show that,the total pressure loss coefficient and outlet steam flow angle increase with the increase of the notch depth when the notch appears on the trailing edge of the stator blade.With the increase of the notch depth,the erosion at the middle and rear edges of the rotor blade increases,and the efficiency of the governing stage decreases rapidly.The decreasing trend of efficiency varies with the type of notch,and the maximum efficiency of governing stage can be reduced by 4.06%when the depth of notch reaches 20mm.When there are different types of notches on the trailing edge of the stator blade,the erosion characteristics of solid particles on the rotor blade change obviously.When type-C notches appear on the trailing edge of the stator blade,the erosion of solid particles is serious in the middle and high section of the trailing edge of the rotor blade.When type-D notches appeared in the trailing edge of the stator blade,the erosion of solid particles was serious in the upper and lower sides of the rotor blade height.When the type-E notches appears on the trailing edge of the stator blade,the erosion of solid particles is serious in the middle and high section of the rotor blade.With the increase of the notch depth,the erosion at the middle and rear edges of the rotor blade increases.