The Research Of Overspeed Atomization Behavior In Secondary Cooling Zone Of Continuous Casting

The secondary cooling of continuous casting has an important impact on the quality of the slab.The cooling intensity experienced by the high temperature slab is closely related to the renewal rate of the water vapor film on the surface of the slab,and is directly related to whether the water drop effectively penetrates the vapor film interface,which is under the influence of droplet size and speed.With the development of high-speed continuous casting technology,the requirement for secondary cooling of continuous casting slab is getting higher and higher.How to further optimize the existing atomizing nozzles for secondary cooling to obtain a more uniform and intense cooling effect is very important for high-speed continuous casting.In this paper,a secondary cooling nozzle spray test bench is established,and an accelerating ring device installed inside the nozzle is designed.By experiments,the effects of process parameters on the droplet speed,size and distribution of the gas-water atomizing nozzles before and after improvement are studied.Using the numerical simulation method,the water velocity and volume distribution of the nozzle inside and the spout under the different working conditions are studied.The main conclusions of this paper are as follows:(1)With the increase of intake pressure,the volume fraction of liquid phase at the nozzle orifice is significantly reduced,the atomization effect of spraying is better,and the liquid phase velocity of nozzle orifice is obviously increased,the speed of liquid phase increases.(2)With the increase of inflow pressure,the volume fraction of liquid phase at the nozzle orifice increases obviously,the atomization effect of spraying becomes worse,the liquid velocity at the orifice decreases and the velocity of liquid phase decreases.(3)The accelerating ring device is installed on the gas path of the gas-water atomizing nozzle.And compared with the nozzle before improved,the impact and acceleration of the air flow in the nozzle after improved is stronger,and the mixing of gas and water is more uniform under the same working conditions.(4)The volume fraction of liquid phase and the liquid velocity of the nozzles before improved in the two sides of the fan-shaped incision fluctuate greatly.However,the nozzles after improved can effectively improve the uniform distribution of liquid volume fraction in the orifice and the stability of liquid phase speed.