Study On The Action Law And Application Basis Of CO₂ Injection Into Blast Furnace Tuyere

The metallurgical industry is a major producer of CO2.In order to absorb part of CO2 for itself,metallurgical workers propose to use CO2 as a resource for their own industry and the technology of CO2 resource utilization in the steelmaking is becoming mature,but there is less technical research on the technology of CO2 resource utilization in the blast furnace.In this paper,the effect of CO2 injection at tuyere on the smelting process of blast furnace is studied and the process of CO2 injection into blast furnace tuyere is developed.Firstly,the influence of CO2 on pulverized coal combustion behavior and pulverized coal burnout rate is analyzed through thermogravimetric experiment and numerical simulation.The thermogravimetric experiment results show that increasing the oxygen content and the initial inlet temperature of the mixed gas can reduce the adverse effects of CO2 gas on pulverized coal combustion.The numerical simulation results show that when the oxygen content is 22.7%and the carbon dioxide enrichment rate of hot air increases from 0%to 6%,the proportion of CO2 participating in the reaction increases from 0%to 1.28%,the outlet temperature of the raceway decreases by 52K,and the burnout of coal increases by 1.15%.Based on the change of the gas composition at the outlet of the raceway and a series of experiments,the influence of CO2 injection into the tuyere of the blast furnace on the metallurgical behavior of the burden is analyzed.The results show that when the carbon dioxide enrichment rate increases from 0%to 4%,the gas permeability of the burden is improved most obviously;When the carbon dioxide enrichment rate increases from 4%to 8%,the reduction degree of the charge increases the most,from 55.9%to 66.5%;At the same time,it is found that with the increase of carbon dioxide enrichment rate,the change of atmosphere has little effect on the low-temperature pulverization of burden.The influence of CO2 injection at the tuyere of the blast furnace on the smelting process in the blast furnace is complex.In order to analyze the change of the reaction in the furnace after CO2 injection at the tuyere of the blast furnace as a whole,a model for the material and heat balance of the blast furnace containing CO2 gas in the hot blast has been established.Through calculation,it can be seen that the hot blast consumption decreases by about 15.4Nm3/t,the direct reduction degree decreases by about 0.0072,and the CO gas concentration in the top gas increases by about 0.64%and the gas temperature at the top of the furnace decreases by about 46℃ for every 1%increase in carbon dioxide rich rate.Based on the basic theoretical research,an experimental platform for CO2 injection into the tuyere of a 1780m3 blast furnace in Taishan steel was built.Through industrial experiments,the accuracy of the kinetic model of the reaction between CO2 and coke,the blast furnace materials containing CO2 in the hot air and the energy balance model are verified.At the same time.the expe rimental results show that when the carbon dioxide enrichment rate increases to 1%,the smooth running of the blast furnace will be affected,and it is clear that reasonable thermal compensation measures are the premise for CO2 injection into the tuyere of the blast furnace.Finally,according to the action rule of CO2 under the working condition of the blast furnace and the CO2 reaction characteristics,the process of CO2 injection into the tuyere of the blast furnace is developed,and the feasibility of applying this process to the traditional blast furnace and the joint production process of steel industry and chemical industry is analyzed.The research results of this paper will provide theoretical and data support for expanding the utilization.of CO2 resources in the metallurgical industry.