Numerical Simulation Of The Flight Heat Transfer Process Of Blast Furnace Slag Particles In The Granulation Chamber

In our country,the steel industry as high energy consumption and high output of the national economy pillar industry,its industrial energy consumption occupies 15%-20%of total energy consumption of the GDP,and its carbon dioxide emission also accounts for about 25%of the total emission of the entire industry,therefore,the steel industry to promote energy conservation and emission reduction has become inevitable.As the main wastes in the steel industry,the slag's temperature is up to 1400-1500?,and it has a great recycling value because of its high-grade sensible heat resource.At present,the main treatment process for slag in China is water quenching method,but it can not recover the sensible heat,pollute the air and waste water,therefore,dry slag granulation heat recovery process has become a research emphasis in the slag treatment field.Now,the granulating mechanism of slag particles in the centrifugal granulation technology is study more,and there is little research on the heat transfer process of slag particles during flight in the granulation chamber.In this paper,the flight heat transfer process of blast furnace slag particles in granulation chamber is studied,and basing on the computational fluid dynamics method a three-dimensional open system is established,also the Fluent simulation software is used to the numerical simulation with the discrete phase model(DPM)coupling the DO radiation model.This paper researched the effects of air velocity,mass flux of slag particles,diameter and velocity on the heat transfer,discussed the coupling effect of the parameters of composite conditions on the heat transfer of slag particles,also discussed the effect of water wall and the distribution of slag particles on the heat transfer effect in the process of centrifugal granulation were studied.The main research results are as follows:(1)Considering the specific heat capacity of the slag particles with temperature changing,the latent heat of molten slag particles is treated.Considering the radiation between particles,a mathematical model of the flight heat transfer process of high temperature slag particles is established;(2)The effect of working parameters on slag temperature from large to small is as follows:slag particle diameter>mass flow rate>air velocity>slag particle velocity,and the influence on the average temperature of outlet air is in descending order:air velocity>mass flow rate>slag particle diameter>slag particle velocity,also the operation parameters has little effect on heat recovery efficiency;(3)The air velocity,slag particle diameter and slag velocity affect the heat transfer by affecting the flight time of slag particles,and change the temperature of the temperature field.The flight time directly determines the heat recovery rate and the heat transfer result of slag particles.The heat recovery curve has the same trend with the flight time curve in most cases;(4)The air velocity,slag diameter and slag velocity change the distribution shape of internal temperature field by influencing the motion trajectory of slag particles,the temperature of air in the wind direction under the trajectory of slag particles increases obviously,and the vortex is the main cause of high temperature region above the rotor appears the 'bud' shape;(5)The optimized values of working parameters were selected:air velocity 1 m/s,slag mass flow rate 3 kg/s,particle diameter 3 mm,slag velocity 4 m/s;(6)The water wall has a strengthening effect on the heat transfer of the slag particles,increasing 33%of the heat recovery efficiency,and the heat transfer emission when the slag particles are launching horizontally and using the single diameter launches is less than 5%of the actual working conditions,the deviation is small.