Pattern Optimization of O-2-CO2 Mixed Injection for Decarburization Reactions During Steelmaking Process

摘要

An increasing number of people have been giving attention to the application of CO2 in the steelmaking process. To determine the optimal substitution ratio of blowing O-2 with CO2, a thermodynamic analysis and a mass spectrometry monitoring experiment of gas composition changes during O-2-CO2 decarburization were used to build a better O-2-CO2 mixed injection pattern. The decarburization process is divided into the first, middle, and final stages to analyze the effect of different ratios of mixed gas at different stages. The results show that using O-2-CO2 mixed gas in the first or middle stage is more conducive to adjusting the temperature of the molten bath; however, using mixed gas in the middle or final stage is more conducive to improving the quality of the furnace gas and saving more oxygen. Based on the thermodynamic calculation, the injection pattern of 70% O-2-30% CO2 gas in the middle stage and pure oxygen in other stages can save 6.3% O-2 and increase the CO proportion of gaseous products by 1.2% comparing to those of conventional pure O-2 blowing in the whole process. Moreover, based on the mass spectrometry method, middle stage at 1773 K and with 2 mass% [C] has the best decarburization kinetic conditions, and its overall reaction rates are larger than the first stage at 1573 K and 3.5 mass% [C] and final stage at 1873 K and 0.5 mass% [C] as long as P-O2 is larger than 0.4 atm. The CO proportion of the outlet gas improves by more than 2.0% when the CO2 substitution ratio in the O-2-CO2 mixed gas is 30% or 40% which is consistent with the thermodynamic calculation results. [GRAPHICS]