Study On Erosion Mechanism Of The Cyclone And Effect Of Local Erosion On Its Performance

Cyclone separator,as a typical gas-solid separation equipment,is widely used in industrial production.When dealing with high hardness and high corrosive particles,the erosion of the wall aggravated,which not only leads to a significant shortening of the service life,but also causes the size change of key parts,and ultimately affects the separation performance.The wall perforation caused by severe erosion will lead to unplanned parking,resulting in huge safety risks and economic losses.Therefore,it is of great engineering application value to carry out research on the erosion mechanism of cyclone separator and the influence of local erosion on its performance.In this paper,the flow field and erosion characteristics of the Stairmand cyclone were numerically simulated by using the Reynolds stress model,particle discrete phase model and E/CRC erosion equation based on Eulerian-Lagrangian approach.The results show that there are local erosion areas in the cyclone,such as the wall opposite to the inlet,the top cover caused by the top ash ring,the spiral erosion groove in the separation space,and the end of the cone.Among them,the local erosion of the wall opposite to the inlet is the most serious.With the increase of inlet velocity and particle concentration,the erosion range and rate of the cyclone increase significantly,but the main erosion part is still the wall opposite to the inlet.Fine particles have good following ability and strong randomness of trajectory,resulting in scattered erosion area on wall surface.Coarse particles have regular trajectory and tend to form high-speed rotating particle belts which cause more obvious spiral erosion on the wall.The local erosion causes the change of wall geometry,which leads to the deflection of airflow direction,and its centripetal velocity component promotes the formation of short-circuit flow.With the intensification of local erosion,the fluid flow in the area below the inlet of the exit pipe decreases,the tangential velocity of the outer vortex decreases,and the centrifugal force on the particles decreases.The escape phenomenon of fine particles is more obvious,and the trajectory of coarse particles tends to coincide,which makes it easier to form high-concentration ash ring to increase particle short circuit and aggravate wall erosion.Compared with the condition without erosion,when the inlet velocity is 14 m/s and the local erosion thickness is 15 mm,the separation efficiency of the Stairmand cyclone for 2μm particles decreases from 82.81%to 62.61%,the cut off diameter d₅₀ increased from 1.41μm to 1.81μm,and the pressure drop decreased from 394.40Pa to 296.45Pa.The local erosion perforation makes the wall geometry no longer closed,resulting in leakage of the airflow,and its centrifugal velocity component weakens the formation of outer vortex and secondary flows.With the increase of the local erosion perforation diameter,the fluid flow in the separator decreases sharply and the tangential velocity decreases greatly,which greatly reduces the centrifugal force on the particles.A large number of particles escape,the number of fine particles escaping from the exit pipe decreases,and the trajectory of coarse particles is increasingly dispersed,which intensifies the collision between particles.Compared with non-erosion perforation,when the inlet velocity is 14m/s and the local erosion perforation diameter is 15mm,the separation efficiency of the Stairmand cyclone for 5μm particles is reduced from 100%to 61.99%,the cut off diameter d₅₀ increased from 1.62μm to 2.69μm,and the pressure drop decreased from 394.40Pa to 114.07Pa.The research results provide theoretical guidance for structural optimization,erosion reduction design of the cyclone and safe and stable operation of the industrial device.