Enhancing Mechanism Of Steel Slag On Steam-Coke Oven Gas Reforming For Hydrogen-Rich Gas Production

Steelmaking industry and coking industry of China have a large scale.As a by-product of the steelmaking and coking industries,utilization of steel slag and coke oven gas（COG）become a urgent issue.The main purpose of this thesis is to study promotion effecs of steel slag on hydrogen production from steam reforming of coke oven gas.The steel slag is used as raw material to prepare adsorption material of CO₂,to enhance the steam reforming of coke oven gas.A Ni-Ca/Al₂O₃ catalyst is prepared by impregnation method,and was applied as reforming catalysts.Enhancement from steel slag CaO and steel slag leaching slag are evaluated under different working conditions.The main findings are as follows:Based on the Chemkin calculation platform and the detailed reaction mechanism,benzene and toluene were used as tar moldings to simulate the steam-coke oven gas reforming.The effects of steam-carbon ratio,concentration of oxygen,temperature,space velocity on the reforming process were studied.The increase of steam-carbon ratio was beneficial to the conversion of CH₄ and the amplification radio of H₂.The increase of oxygen concentration was beneficial to the conversion of CH₄,but the oxidation of hydrogen reduces the amplification radio of H₂.The increase of the axial flow velocity at the inlet reduced the conversion of CH₄,affected the production of H₂.The increase of CO concentration increased the amplification radio of H₂ due to the water gas shift reaction.The steel slag-based CaO was prepared by using steel slag as raw material.At600°C,650°C and 700°C,the adsorption capacity of CO₂ reached 44.78%,57.35%and 50.10%,respectively.The Ni-Ca/Al₂O₃ catalyst has a good catalytic effect on steam-coke oven gas reforming,and the conversion of CH₄ was 90%higher at 700°C.The simulated coke oven gas（CH₄,CO and CO₂）was used as raw gas to investigate the amplification radio of H₂ and conversion of CH₄ in the steam-coke oven gas reforming.The selectivity of CO and CO₂ was related to reforming temperature,space velocity,catalyst-sorbent ratio and steam-carbon ratio.The promotion of CaO（AC）and CaO（SL）on the steam-coke oven gas reforming with adsorption enhanced was investigated.At the conditions of 1.5g steel slag CaO,4.5g Ni-Ca/Al₂O₃,700°C,S/C=4,50mL/min of inlet gas.At the prebreakthrough stage,the conversion of CH₄ reached94.33%.The amplification radio of H₂ reached 10.8.Increasing the mass of the adsorbent from 1.5g to 2.5g,the amplification radio of H₂ at the prebreakthrough and breakthrough stage were 10.21 and 10.19,respectively.Compared with CaO（AC）as the adsorbent of reforming reaction,using steel slag-based CaO,the conversion of CH₄ at the prebreakthrough stage was 52.77%higher,and the amplification radio of H₂ was 4.88 higher.At the breakthrough stage,the conversion of CH₄ was 63.85%higher and the amplification radio of H₂ was 5.22higher.At the conditions of 2.5g steel slag CaO,4.5g Ni-Ca/Al₂O₃,700°C and S/C=4.The gas volume of inlet was increased from 50mL/min to 100mL/min,in the breakthrough stage,the conversion of CH₄ decreased by 26.13%.The amplification radio of H₂ decreased by 2.32.At the breakthrough stage,the conversion of CH₄decreased by 30.85%,and the amplification radio of H₂ decreased by 2.75.During the reforming reaction,the conversion of CH₄ and production efficiency of H₂ reduced with the input volume gas increased from 50 mL/min to 100 mL/min.Reducing the space velocity increased the contact time between the reaction gas and the catalyst,promoted the steam reforming of CH₄,and increased the amplification radio of H₂.At the conditions of 2.5g steel slag-based CaO,4.5g Ni-Ca/Al₂O₃,S/C=4 and50mL/min of inlet gas.At 600°C,650°C and 700°C,the conversion of CH₄ at the prebreakthrough stage were 76.03%,66.27%and 83.06%,respectively.The amplification radio of H₂ were 9.89,9.45 and 10.21,respectively.At the conditions of 2.5g steel slag CaO,4.5g Ni-Ca/Al₂O₃,700°C and50mL/min of inlet gas.The steam-carbon ratio increased from 3 to 4,the conversion of CH₄ in the prebreakthrough stage increased by 1.76%.The amplification radio of H₂ increased by 0.04.The selectivity of CO decreased by 12.52%.At the breakthrough stage,the conversion of CH₄ increased by 7.12%,and the amplification radio of H₂ increased by 0.73.The selectivity of CO dropped by 11.95%.Based on the utilization of Ni-Ca/Al₂O₃ catalyst and steel slag-based CaO,the effect of leaching slag was further studied.According to the experimental results,the selectivity of CO from high to low is slag-free,post-slag,mixed slag and pre-slag,and Fe in the leaching slag promoted the water gas shift reaction.