| The steel industry is one of the energy intensive industries,and the energy consumption of steel production accounts for 15%of the total energy consumption of national economy.Each ton of blast furnace slag contains about 1500 MJ heat,and the waste heat in the blast furnace slag has not been effectively recycled.This paper proposes a blast furnace slag quick cooling and breaking technology,which can quickly break and cool the blast furnace slag to below the glass phase transition temperature,achieving the purpose of double recycling of energy resources.In this paper,a quick cooling and breaking device was developed.The numerical simulation and experimental research were used to study the cooling characteristics of blast furnace slag and the fracture performance of the device.The effects of particle diameter and heat transfer intensity on the cooling time and internal temperature distribution of slag particles were studied by numerical simulation.The simulation results show that when the particle center is cooled to1000K,the larger the size of the slag particles,the longer time is required.The cooling time required for the 4 mm diameter particles is 13 times as long as that of the1 mm diameter particles.The larger the diameter,the greater the temperature difference of the grain section after cooling.The larger the convective heat transfer coefficient on the surface of slag particles,the shorter the cooling time.The convective heat transfer coefficient increases from 100W/(m~2·K)to 1400W/(m~2·K),and the cooling time decreases from 17.25s to 2.32 s.Combined with the simulation results and thermal calculation,the blast furnace slag quick cooling and breaking device was designed and fabricated,and the simulation experiment was carried out on this basis.The crushing performance of the device was tested by using a 4:1 mixture of rosin paraffin.The fragmentation of mixture was investigated by nozzle type,flow rate and pressure.The experimental results show that:(1)The 6520 nozzle has the best breaking effect on the mixture.The overall particle size after breaking is smaller,mainly distributed between 0.1 and 1mm.(2)The particle size of the mixture decreases with the increase of nozzle pressure and flow rate.The pressure increases from 0.12 MPa to 0.33 MPa,and the average particle size decreases from 0.67 mm to 0.39 mm,while the larger the pressure and flow rate,the less the adhesion of the mixture on the wall.The on-site experiment of hot slag was carried out.The experimental results show that:(1)The 6530 nozzle has the best breaking effect on the hot slag.The particle size of the slag after the hot state experiment is mainly distributed between1mm and 3.5 mm.The particle size of the mixture is larger than that of the simulated experiment.(2)In the hot state experiment,the liquid slag has almost no bond on the wall of the device,but there is a little fibrous slag in the slag after crushing.(3)The change rule of the particle size of the slag in the hot state experiment is the same as that of the simulation experiment.With the increase of nozzle flow rate and pressure,the particle size decreases after breaking.(4)The glass phase content of the slag after breaking and cooling is 93.8%,which can ensure the high additional utilization value. |
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