Research On Cooling And Heat Recovery Methods And Devices For Molten Metallurgical Slag

Aiming at the technical problems of traditional air quenching treatment of molten metallurgical slag with low glass transition rate,low hot air quality and large energy consumption,the paper studies the granulation cooling and waste heat recovery pro-cess of slag under the action of air powder flow.As a result,a new slag granulation cooling and heat recovery device was designed,and the heat utilization path of the metallurgical slag in the device was analyzed.The following conclusions were ob-tained:The slag should form glassy during the granulation cooling process,and its for-mation depends on the cooling rate before the slag completes solidification.The criti-cal cooling rate is 58K·s^-1.According to the thermodynamic analysis of the slag gran-ulation cooling process,it is obtained that when the slag particle size is 4 mm or more,the actual cooling rate is lower than the critical cooling rate.Lowering the cooling air temperature and spraying water mist in the cooling air can increase the cooling rate.The conditions for the critical cooling rate of slag 4?5mm and above 5mm are the ini-tial cooling air temperature of 293K,and the amount of water mist sprayed is0.42kg·s^-1 and 0.34kg·s^-1.Under the operating conditions of heat exchange of slag with different particle sizes and cooling air,the slag takes 6.59s to complete the gran-ulation cooling process;the cooling air heating rate gradually decreases with the cooling time and approaches the end temperature of 854K at 7s.Based on the dynamic analysis of the slag flight process,the slag flight space length was 22m,the ascent height was 4m,the descent height was 11mm and the ini-tial flight angle was 30°.Under this condition,the distribution of falling point law was obtained,and the slag was flying horizontally distance increases as the particle size decreases,and the same slag particle size interval increases its horizontal distribution range as the particle size decreases;and the slag below 4mm completes solidification in flight,and the 4mm and 5mm slag are completed separately 87% and 75% of the solidification process.Improve a new type of slag granulation and heat recovery device.The structure of the device enables cooling air of different temperatures and flows to segment the slag of different particle sizes.Water mist is sprayed into the cooling air of large par-ticle slag separately to increase the cooling rate.At the same time,the fin-type air cooling jacket reduces the wall temperature of the granulator,realizes the preheating of the cooling air,and increases the final temperature of the cooling air outlet.Im-prove a new type of gas-solid moving bed waste heat recovery device,which adopts a two-stage structure of upper and lower stages.The upper stage accumulates heat transfer and the lower stage is perforated inclined plate heat transfer.Through the analysis of the overall thermal balance of the granulation and heat recovery process of the metallurgical slag composed of the two devices,the final air temperature during the cooling process of the granulation of the metallurgical slag is 854K,and the final temperature of the air during the residual heat recovery of the moving bed is 884K.The comprehensive heat recovery rate is 79.91%.