中空纤维膜接触器脱碳和传质性能的数值研究

Numerical study on absorption of carbon dioxide and mass transfer performance in hollow fiber membrane contactor

中空纤维膜吸收烟气中CO2是一种清洁、高效、最具潜力的脱碳技术方法之一。本文建立了一个二维的中空纤维膜接触器平行逆流吸收混合气中CO2的非润湿模型。考虑轴向和径向扩散,模拟了EEA、EDA和PZ 3种吸收剂在不同操作条件下对CO2的脱除效果和传质性能。结果表明:脱碳性能从大到小为PZ>EDA>EEA;气相参数对脱碳和传质的影响比液相参数更显著;提高气体流速、CO2浓度和气温,脱碳率均会下降;提高液速、吸收剂浓度和液温,脱碳率均增大,而传质速率只有在提高气温时会下降,其他参数的升高均会使其增大;应采用适当的液相参数,防止操作参数过高带来的不利影响。

A type of process, which absorbs carbon dioxide （CO2） from flue gas in hollow fiber membrane contactor, has been considered as one of clean, high efficient and the most promising decarburization technologies. A two-dimensional mathematical model was developed for absorption of CO2 from parallel countercurrent mixed gas by hollow fiber membrane contactor. By using finite element method, CO2 removal（decarburization） and mass transfer performance of three absorbents EEA（ethyl-ethanolamine）, EDA（ethylenediamine） and PZ（piperazine） were simulated at various operation conditions in which axial and radial diffusion in membrane contactor as well as diffusion in fiber and membrane pores and non-wetting condition were considered. The simulation results show that the order of decarburization performance is PZ〉EDA〉EEA. The influence of the gas phase parameters on CO2 removal and mass transfer is more significant than that of liquid phase parameters. With increase of gas flow rate, CO2 concentration, and gas temperature, the decarburization efficiency decreases. While the CO2 removal efficiency goes up when liquid flow rate, solvent concentration, and liquid temperature increase. However, the CO2 mass transfer rate speeds up with increase of all parameters except gas temperature. So, the suitable control of liquid parameters is required, which are not over high to prevent adverse effects on CO2 absorption.