Study On Hot Delivery And Hot Charging Technology Of Continuous Casting Slab

As a pillar of the national economy and a major energy consumer,iron and steel enterprises have carried out a series of ultra-low emission,energy-saving,and consumption reduction transformations in the face of increasingly severe resource and environmental problems.Among them,the hot delivery and hot charging process applied in the casting rolling process interface has been promoted all over the world,and its energy-saving effect has been unanimously recognized.In this paper,the hot delivery and hot charging production line of a domestic iron and steel enterprise is taken as the research object.By measuring the slab temperature and collecting the production parameters of the continuous casting slab,the numerical physical model of the whole production process of liquid steel cooling and solidification,slab roller transport,and in furnace heating is established.The temperature nephogram distribution and heat change of the slab from the continuous caster to the reheating furnace are calculated by using the finite element method.The similarities and differences of slab in furnace heating process are discussed.At the same time,the measurement test of rolling furnace condition was carried out.Combined with the production parameters such as the temperature of each section of the furnace,air gas flow rate,flue gas flow rate,and the numerical simulation results of the slab heat absorption,the heat balance and fuel consumption of the furnace for heating the slab with different charging temperatures were calculated.This paper evaluates the influence of hot delivery and hot charging process on the energy efficiency of heating furnace,and puts forward some optimization suggestions for the existing hot delivery and hot charging process.The main conclusions are as follows:(1)The heat loss on the hot roller table is about 20.77% of the heat loss of the slab out of the caster.The average temperature of hot charging slab before charging is about772.16 ?.The sensible heat of slab which can be used by hot delivery and hot charging process accounts for 57.11% of the heat of slab when it comes out of continuous caster.If the process is connected properly,the roller transport speed can be increased to improve the sensible heat utilization of slab;(2)During the heating process of cold casting billet,the cross-section temperature of the slab is distributed in an ellipse-like shape,which is increasing from inside to outside.The corner temperature is the highest,the narrow surface is the second and the core is the lowest in the whole heating process.During the charging of hot casting billet and quenched casting blank,a large number of physical heat is found in the core.In the early stage of furnace heating,the section shows the highest temperature of wide surface center and the second in the core The temperature distribution of the inner side of the narrow surface is the lowest,the core temperature first drops and then rises,and the temperature distribution of the section in the middle and later heating period is the same as that of the cold installation;(3)No matter what kind of billet is heated,the reaction heat of gas combustion is the main source of heat revenue.The reaction heat accounts for 84.60% of the heat revenue when heating the cold charging billet and 79.84% when heating the hot charging billet.The thermodynamic energy brought in by air accounts for the second of the heat income,while the thermodynamic energy brought in by coal gas accounts for the least;(4)The total heat absorption of cold charging slab in furnace is about 586.70 k J/kg,that of hot charging slab in furnace is about 205.35 k J/kg,that of quenched charging slab in furnace is 231.85 k J/kg,and that of quenched charging slab in furnace is only12.90% more than that of hot charging;(5)Because of the high physical heat in the hot charging,the proportion of heating furnace heat expenditure of the hot charging billet accounts for 25.59% less than that of the cold casting.The burning consumption per ton of steel for the hot cast billet is1.240 GJ,and that of the hot cast billet is 0.895 GJ.Compared with the cold charging heating process,the existing hot charging heating process can save 11.806 kg of standard coal for one ton of steel production;(6)The existing heating process of hot charging billet and quenching charging billet has the problem of a long time of billet in furnace,which cannot effectively play the energy-saving advantage of the hot charging process.It can be optimized from two aspects: reducing billet in furnace time,improving the production efficiency of heating furnace,reducing furnace temperature,and reducing gas input;(7)If the existing hot delivery and hot charging process can adjust the production rhythm,improve the connection of the hot rolling process,and shorten the time of hot charging billet in furnace from 4.704 h to 3.5h,the optimized hot charging billet heating process can save about 19.620 kg standard coal per ton of steel production compared with the cold charging billet heating process,with remarkable energy-saving effect;(8)When the in furnace time of quenched billets is reduced to 3.696 h,and the temperature difference is 8.5 ? which is the same as that of hot billets after optimization of heating time,the optimized heating process of quenched billets can save about 18.348 kg standard coal per ton steel production compared with that of cold billets.