Ironmaking Process Model Based On Oxygen Blast Furnace With Hot Charging

Recycle of the sensible heat is not complete for the materials with medium and low temperatures during the traditional coking, sintering and pelletizing process, and the low energy utilization rate results in a lot of heat wasting. Therefore, oxygen blast furnace with continuous hot charging method is proposed, and the model of corresponding raw material preparing process is established to be solved for the optimal process parameters. The systematic model of ironmaking is on the basis of material and energy conversation principles, which includes blast furnace model, coking model, sintering model and pelletizing model respectively. The dependences of oxygen enrichment rate, blast temperature and charging temperature on energy consumption are studied, meanwhile, the material flow and energy flow of the ironmaking system are analyzed.According to the calculation results and relevant analyses, five conclusions are presented as follows:(1)The energy consumption of blast furnace process decrease with the oxygen enrichment rate and blast temperature increasing, while the value decrease to the minimum and then raising with the increase of hot charging temperature. Combination with the limitation of theoretical combustion temperature, the optimal operating parameters are oxygen enrichment rate of29%, blast temperature of25℃, and charging temperature of150℃respectively, which result in the lowest energy consumption of375.77kgce/tHM.(2)Provided that hot charging temperature is constant:when the oxygen enrichment rate changes from0%to29%which results in the changing of top gas composition of the blast furnace, accordingly, the average energy consumption of coking reduces by1kgce/t, and the average consumption of heating gas of coking reduces by71m3/t; the average energy consumption of pelletizing reduces by4kgce/t, and the average consumption of heating gas of pelletizing reduces by68m/t; however, the changes of oxygen enrichment have little influence on the energy consumption and gas utilization of sintering process.(3)Provided that the oxygen enrichment rate is consistent, top gas temperature goes up with the increasing of charging temperature. When the gas temperature changes from25℃to800℃, accordingly, the average energy consumption of coking reduces by3.5kgce/t, and the average consumption of heating gas of coking reduces by54m3/t; the average energy consumption of pelletizing reduces by3kgce/t, and the average consumption of heating gas of pelletizing reduces by44m3/t; however, the changes of charging temperature have little influence on the energy consumption and gas utilization of sintering process.(4) When the oxidation degree reaches the theoretical maximum value0.75, an series of optimal operating parameters are obtained in which the oxygen enrichment rate is29%, the blast temperature is25℃and the charging temperature is800℃respectively. Under these optimal conditions, the energy consumption of the whole ironmaking system reduces from606.81kgce/tHM to539.30kgce/tHM.(5) From the views of the systematic material flow and energy flow, comparisons between the traditional processes and the newly proposed processes are executed based on1ton hot metal. Coke rate reduces from371.3kg to291.4kg; The burden sensible heat of1.62GJ can be directly recycled which is required from the hot air in traditional processes. It can not only maintain the heat balance, but also reduce energy consumption in the hot blast stove process; In the newly proposed processes, top gas volume is sufficient for recycling in the inner system. Moreover, the surplus top gas with sensible heat of1.3GJ can be saved.