膜基活化溶液中活化剂在回收温室气体CO2过程中的作用
Role of activators in membrane-based activated solutionsin recovery of greenhouse gas CO2
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摘要: 将AMP和PZ作为活化剂添加于MDEA溶液中,形成活化溶液,研究了膜基活化溶液回收温室气体CO2性能,着重考察活化剂的活化作用和对膜接触器传质加强的影响,提出一个活化机理来解释活化现象,建立了阻力层方程模型, 并模拟膜基活化溶液回收CO2的传质过程。结果表明,活化剂对膜接触器传质的加强起到重要作用,具有双氨基环状结构的PZ对传质的加强作用高于具有空间位阻结构的AMP;活化溶液的CO2回收率和传质通量明显高于未活化的MDEA溶液,活化性能PZ>AMP;活化剂的活化效应与分子结构有关;流体力学的改变对传质的影响有限,活化剂的反应动力学对传质的加强起主导作用;阻力层方程模型能较好地模拟膜基活化溶液回收CO2传质过程,传质通量和总传质系数的模型值与实验值符合较好。Abstract: Piperazine (PZ) and 2-amino-2-methyl-1-propanol (AMP) were used as activators and they were respectively added into aqueous methyldiethanolamine (MDEA) to form activated solutions. Performances of CO2 absorption into the activated solutions in a membrane contactor were investigated. Emphasis on the study of effects of activation on enhancement of mass transfer was performed. An activation mechanism was presented to explain the activation phenomena. A resistanceinseries model was established and simulated the mass transfer of the process of membranebased activated solutions for CO2 reclaiming. The results show that the activators play a significant role in enhancement of mass transfer of the membrane contactor. CO2 reclaiming efficiency and masstransfer flux of the membrane contactor using the activated solutions are evidently larger than that using the nonactivated MDEA solution. Effect of PZ with bi-amino structure on enhancement of mass transfer is higher than that of AMP with sterical hindered structure. The molecule structures of activators contribute to activation. Effect of hydrodynamics on mass transfer is limited. Dominant effect on mass transfer enhancement is kinetics of chemical reaction of the activators with CO2. The resistance-in-series model can simulate the mass transfer flux and overall mass transfer coefficient of membranebased activated solutions for CO2 reclaiming. Model values are in good agreement with the experimental values.
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