【作者】 马雨联；

【导师】 张卫东；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2012， 硕士

【摘要】 中空纤维膜解吸过程作为一种新型的低能耗CO₂解吸工艺，结合了中空纤维膜接触器作为传质分离设备的优点以及热解吸过程的优点。中空纤维膜接触器具有巨大的传质比表面积，可以有效地提高解吸过程的传质传热效率。在中空纤维膜解吸工艺中，气、液两相分别在膜的两侧流动，不仅可以避免传统解吸设备的雾沫夹带、液泛等操作问题，并且气液两相可以独立调节，增大了解吸过程的操作弹性，可以通过分别调节气、液两相的操作条件，同时达到提高解吸效率、降低解吸能耗的目的。论文使用PP（聚丙烯）和PTFE（聚四氟乙烯）中空纤维膜接触器，研究了吸收剂种类、吸收剂浓度、解吸温度、液相流速、气相操作条件、膜材料和膜器结构参数等因素对膜解吸过程解吸效率和解吸能耗的影响，初步探索了膜解吸过程的传质机理，分析了各影响因素对膜解吸过程解吸效率和解吸能耗的作用机制。实验结果表明，增大吸收剂浓度、吸收剂中CO₂的负载量、解吸温度、以及液相流速均可以提高CO₂的解吸效率，而气相操作条件则对CO₂解吸效率影响甚微；增大吸收剂的浓度、解吸温度和液相流速，可以降低膜解吸过程中吸收剂的升温能耗；增大吸收剂浓度、气相采用低流速的正压吹扫方式、降低解吸温度可以降低解吸过程中水的蒸发能耗，而液相流速对水的蒸发能耗影响较小。论文研究表明，在液相流速为227.46cm·min^-1，气相采用14.0cm·s^-1°的正压吹扫方式，解吸温度为90C的较优操作条件下，使用PP中空纤维膜接触器对5.0mol·L^-1的MDEA饱和溶液进行循环解吸，解吸开始的前20分钟内，解吸率迅速增大至90%，到第6分钟时，解吸率已经达到80%，而解吸能耗只有105.55KJ·mol^-1CO₂，远远低于常规解吸的180-200KJ·mol^-1CO₂。更多还原

【Abstract】 As a new type of low-power CO₂desorption process，The CO₂desorption process in hollow fiber membrane contactors combined withboth the advantages of a hollow fiber membrane contactor as the masstransfer separation device and the thermal desorption process. The hollowfiber membrane contactor which has a large mass transfer area in pervolume can effectively improve the heat and mass transfer efficiency ofthe desorption process. In the CO₂desorption process in hollow fibermembrane contactors, respectively the gas phase and liquid phase flow oneach side of the membrane, It not only can avoided the operationalproblems such as entrainment, flooding which happened in the traditionaldesorption equipment, but also the gas phase and liquid phase can beadjusted independently, therefore the operation has larger elasticity. Inhollow fiber membrane contactors, liquid phase and gas phase can beadjusted independently, so it is feasible that adjusting the liquid conditionto improving the desorption efficiency and changing gas phase condition to reducing the energy consumption synchronously.In this paper, the PP and PTFE hydrophobic porous hollow fibermembrane contactors which have huge interfacial area per volume hasbeen used for carbon dioxide desorption. The effect of various parameterssuch as the absorbent types, the concentration of MDEA solution, flowrate of liquid phase and gas phase, temperature, the operating conditionsof gas phase, membrane materials and the device structure parameters ofmembrane contactors on CO₂desorption efficiency and energyconsumption were investigated, and high desorption ratio and masstransfer flux were obtained, the energy consumption reduced on the sametime. The mass transfer mechanism of the desorption process in hollowfiber membrane contactors has been investigated. The experimentalresults show that the carbon dioxide desorption efficiency was improvedby the increasing of the concentration of MDEA, the saturation level ofCO₂in absorbent, the temperature, liquid flow rate and mass transferarea. However, the gas phase condition had little effect on CO₂desorptionefficiency but obvious effect on energy consumption in membranecontactors. The reheating energy consumption of CO₂desorptionprocess in hollow fiber membrane contactors can be reduced byincreasing MDEA concentration and liquid flow rate. The evaporationheat of water can be reduced by increasing MDEA concentration andreducing gas phase flow rate when the tube side of contactor was taken sweeping with positive pressure, but it is useless by changing the liquidflow rate. The effect of desorption temperature on the desorption energyconsumption was restricted by the gas operating conditions.The performance of desorption efficiency and energy consumptionin membrane desorption process is excellent. In the optimal conditionswhich liquid flow rate was227.46cm·min^-1, the gas flow rate was14.0cm·s^-1, the desorption temperature of90°C, the desorption ratio increasedrapidly to over90%when CO₂was released from5.0mol·L^-1MDEAsolution in PP hollow fiber membrane contactor within began20minutesthe desorption rate has reached80%at6th minute, while the desorptionenergy consumption is only105.55KJ·mol^-1CO₂which was far lowerthan the conventional desorption180-200KJ·mol^-1CO₂.更多还原