Ho Chii-Dong, Chang Hsuan, Chen Yu-Han, Chew Thiam Leng, Ke Jui-Wei
Department of Chemical and Materials Engineering, Tamkang University, New Taipei 251301, Taiwan.
Department of Chemical Engineering, Faculty of Engineering, Universiti Teknologi PETRONAS, Seri Iskandar 32610, Malaysia.
Membranes (Basel). 2023 Feb 19;13(2):249. doi: 10.3390/membranes13020249.
The absorption efficiencies of CO in ceramic hollow-fiber membrane contactors using monoethanolamine (MEA) absorbent under both cocurrent- and countercurrent-flow operations were investigated theoretically and experimentally; various MEA absorbent flow rates, CO feed flow rates, and inlet CO concentrations were used as parameters. Theoretical predictions of the CO absorption flux were analyzed by developing the mathematical formulations based on Happel's free surface model in terms of mass transfer resistances in series. The experiments of the CO absorption were conducted by using alumina (AlO) hollow-fiber membranes to confirm the accuracy of the theoretical predictions. The simplified expression of the Sherwood number was formulated to calculate the mass transfer coefficient of the CO absorption incorporating experimental data. The data were obtained numerically using the fourth-order Runge-Kutta method to predict the concentration distribution and absorption rate enhancement under various fiber packing configurations accomplished by the CO/N stream passing through the fiber cells. The operations of the hollow-fiber membrane contactor encapsulating = 7 fiber cells and = 19 fiber cells of different packing densities were fabricated in this work to examine the device performance. The accuracy derivation between experimental results and theoretical predictions for cocurrent- and countercurrent-flow operations were 1.31×10-2≤E≤4.35×10-2 and 3.90×10-3≤E≤2.43×10-2, respectively. A maximum of 965.5% CO absorption rate enhancement was found in the module with embedding multiple fiber cells compared with that in the device with inserting single-fiber cell. Implementing more fiber cells offers an inexpensive method of improving the absorption efficiency, and thus the operations of the ceramic hollow-fiber membrane contactor with implementing more fiber cells propose a low-priced design to improve the absorption rate enhancement. The higher overall CO absorption rate was achieved in countercurrent-flow operations than that in cocurrent-flow operations.
理论和实验研究了使用单乙醇胺（MEA）吸收剂的陶瓷中空纤维膜接触器在并流和逆流操作下对CO的吸收效率；将各种MEA吸收剂流速、CO进料流速和入口CO浓度用作参数。基于Happel自由表面模型，根据串联的传质阻力建立数学公式，分析了CO吸收通量的理论预测。通过使用氧化铝（AlO）中空纤维膜进行CO吸收实验，以确认理论预测的准确性。结合实验数据，推导了舍伍德数的简化表达式，用于计算CO吸收的传质系数。使用四阶龙格-库塔方法对数据进行数值求解，以预测CO/N流通过纤维单元时，在各种纤维填充结构下的浓度分布和吸收速率增强情况。在本研究中，制作了封装不同填充密度的7个纤维单元和19个纤维单元的中空纤维膜接触器，以考察其装置性能。并流和逆流操作的实验结果与理论预测之间的误差分别为1.31×10-2≤E≤4.35×10-2和3.90×10-3≤E≤2.43×10-2。与插入单个纤维单元的装置相比，嵌入多个纤维单元的模块中CO吸收速率提高了965.5%。增加纤维单元数量是提高吸收效率的一种低成本方法，因此，采用更多纤维单元的陶瓷中空纤维膜接触器操作提出了一种低成本设计，以提高吸收速率。逆流操作的总CO吸收速率高于并流操作。
