Study On Bionic Anti-erosion Technology Of Boiler Heat Tube Base On The Desert Scorpions

The explosion accidents of boiler heat tube seriously threaten the safety of the unit.Although the traditional anti-erosion methods have certain effects,they all have obvious disadvantages.Based on the surface characteristics of desert scorpions,the bionic structure was extracted.Furthermore,the numerical simulation method was used to study the anti-erosion characteristics,anti-erosion mechanism and optimal size combination of the bionic structure.Finally,the bionic structure was applied to the tubes,the anti-erosion effect and relevant erosion characteristics were researched through experimental methods,which provide a new idea for the anti-erosion of boiler heat tube.The main research content includes:Firstly,in order to study the anti-erosion characteristics of bionic surface,groove surface,bump surface and groove-bump surface was extracted based on the desert scorpions.The erosion rate distribution was studied by numerical simulation methods.The results show that when the impact angle is less than 70°,all bionic surfaces are effective in anti-erosion.The groove structure has a significant effect,the groove-bump surface has the best friction reduction effect at 45°,and the erosion rate is reduced by 65.3%.The bump structure has a limited effect on the flow field,but it changes the impact angle a lot.While a large-scale vortex structure is formed in the groove structure,which has a greater impact on the flow field and impact speed.The peak value of the erosion rate changed from 30° to 45°,this is because the impact angle of both is about 35°,which is the maximum theoretical wear rate,but the impact speed of 45° is 1.4 times that of 30°.Secondly,based on the previous numerical calculation model,the anti-erosion effect of bionic surfaces among different size combinations were studied.For the groove-bump surface,the erosion rate decreases as the groove width and bump diameter increase.These two parameters have an independent effect on the erosion rate,and the influence of the groove width is greater.As for the groove surface,the erosion rate decreases with the increase of the groove width/groove depth,then tends to be gentle,and finally increases.The optimal groove width/groove depth is between 2.5～3,which perform best in anti-erosion.The distribution law of particle impact speed depends on the scale and strength of the vortex structure in the groove,and the distribution law of particle impact angle depends on the scale and angle of the groove.Finally,the erosion wear test of the tube was carried out,and the groove tube and the groove-bump tube were regarded as the research object,which were made with the material of316 L.The experiment first verified the anti-erosion effect of the bionic tube,and then studied the influence of particle speed,hardness and particle diameter on the erosion characteristics and anti-erosion effect of the bionic tube.The results show that the relative erosion rate of the groove tube is about 0.80,and the groove-pump tube is about 0.76.The erosion characteristics of the bionic tube are similar with the smooth tube when these particle parameters change,it means that the bionic structure don’t alter the erosion characteristics of the material surface.The anti-erosion effect of the bionic tube has no obvious relationship with the particle speed and hardness.While the bionic tube has a lower relative erosion rate when the particle diameter is smaller,therefore,the anti-erosion effect of the bionic tubes is better when the particle diameter decrease.