Investigation Of CO₂ Catalytic Conversion With The Pulverized Coal Injected Into The High Temperature Gas Of Converter

Based on low calorific value and recovery amount of converter gas from the present various steel mills,one newly process is introduced to produce high-quality converter gas by injecting pulverized coal into converter gas with high temperatures.A simple coal injection device is added on the original recovery system of converter.In this process,the harmful CO₂ component in flue gas and catalytic converter dust were used to achieve CO₂ catalytic conversion.In this paper,the thermodynamic theory is used to calculate and analyze the possible reactions between pulverized coal,converter flue gas and dust.The effects of reacted temperature,gas composition and coal particle size on the CO₂ gasification of coal char were studied by a drop-tube furnace system.The components?FeO,Fe₂O₃ and CaO?were used to simulate the converter dust.The catalytic effect of dust on CO₂ gasification of coal char was studied by the drop-tube furnace and a thermogravimetric analyzer.Finally,the actual effects of this new process are verified by industrial tests.The results show that: pulverized coal can produce large amount of gas in the converter evaporated cooling flue,and the productions of H₂ and CO increase while the yields of CH₄ and CO₂ decrease with increasing the temperature.During the evaporated cooling flue,carbon in the coal reacts with O₂ in the flue gas to produce CO,and then reacts with CO₂ to produce CO.Increasing gas temperatures and the CO₂ contents and reducing coal sizes are beneficial to CO₂ gasification of coal char.And temperature is the greatest affecting factor.FeO,Fe₂O₃,CaO and complex agents have catalytic effects on gasification of coal char,which can reduce the starting temperature of gasification reaction by 38?,46?,45? and 58?,respectively,and the finishing temperature can be decreased by 75?,111?,132? and 116?.The activated energy is decreased by 18.18 kJ/mol,28.612 kJ/mol,17.492 kJ/mol and 26.275 kJ/mol,respectively.The catalytic effects of FeO and Fe₂O₃ are mainly to promote the gasification,so that more CO₂ is converted to CO,and the catalytic performance of FeO is greater than Fe₂O₃.The catalytic performance of CaO is mainly determined by the pyrolysis of coal and the productions of H₂ and CH₄ contents.Industrial tests show that this new process can prolong gas recovery time and increase recovery amount of gas.When the injecting rate of pulverized coal is increased from 10 kg·min^-1,20 kg·min^-1 to 30 kg·min^-1,the gas recovery time is increased by 6.06%,9.94% and 11.40%,respectively,while O₂ and CO₂ is decreased by 52.26%,59.79%,63.92% and 22.73%,32.76%,41.19%,respectively.The H₂ and CO contents are increased by 109.82%,191.07%,240.18% and 22.73%,32.76%,41.19%,respectively.