钢铁高炉煤气膜吸收CO2捕集的建模与传质机理

Modeling and Mass Transfer Mechanism of CO2 Capture by Membrane Absorption from Iron and Steel Blast Furnace Gas

  • 摘要: 针对钢铁厂高炉煤气CO2捕集需求,建立了中空纤维膜吸收器对CO2的过程模型,系统研究了膜吸收工艺的关键性能影响因素。模型综合考量了传质、能量衡算、反应动力学及膜润湿机理,采用Aspen Custom Modeler模拟分析了吸收液温度、煤气温度对CO2脱除效率的影响规律,并与传统吸收工艺进行了对比。结果表明,吸收液温度从10 ℃升至80 ℃时,膜吸收工艺CO2脱除率显著降低(从92.8%降至83.1%),主要源于温度升高加剧膜润湿(最大润湿度达74.68%)及促使吸收反应逆向移动;煤气温度从10 ℃升至80 ℃时,因气相扩散速率增大削弱了液相传质,导致膜吸收性能亦明显下降(从88.2%降至75.5%)。膜润湿行为模拟分析显示,膜润湿度随吸收液温度升高而显著增加,且沿膜组件轴向逐渐上升并在达到峰值后趋于稳定。本研究揭示了吸收剂和煤气温度与膜润湿的协同作用对传质效率的制约机制,证实了膜吸收在低温工况下的应用优势,为工艺优化及工业放大提供了理论依据。

     

    Abstract: A process simulation model for CO2 capture using a hollow fiber membrane absorber was developed to address the CO2 capture requirements of blast furnace gas in steel plants. Key factors influencing membrane absorption performance were systematically investigated. The model integrated mass transfer, energy balance, reaction kinetics, and membrane wetting mechanisms. Aspen Custom Modeler was utilized to simulate the effects of absorbent temperature and blast furnace gas temperature on CO2 removal efficiency, with comparisons to conventional absorption processes. Results demonstrated that increasing the absorbent temperature from 10 ℃ to 80 ℃ led to a significant decrease in CO2 removal efficiency from 92.8% to 83.1%, primarily due to intensified membrane wetting (maximum wetting degree reaching 74.68%) and a shift of the absorption reaction equilibrium toward the reverse direction. When the gas temperature increased from 10 ℃ to 80 ℃, membrane absorption efficiency also declined markedly from 88.2% to 75.5%, attributed to enhanced gas-phase diffusion rates that weakened liquid-phase mass transfer. Simulation of membrane wetting behavior revealed a significant increase in wetting degree with rising absorbent temperature, which gradually increased along the absorber axis and stabilized after reaching a peak. This study elucidates the constraining mechanism of the synergistic effects of absorbent and gas temperatures and membrane wetting on mass transfer efficiency, confirming the advantages of membrane absorption under low-temperature conditions and providing a theoretical foundation for process optimization and industrial scale-up.

     

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