[[alternative]]Theoretical and Experimental Studies of Carbon Dioxide Absorption through Membrane Contactors

計畫編號：MOST 106-2221-E-032-039研究期間：2017-08~2018-10研究經費：995,000[[abstract]]針對環境氣候變遷，溫室效應影響逐漸嚴重的情況下，節能減碳是目前各國專家學者的共識，為了達到聯合國訂定的預期減碳目標 [1-4]，本研究利用醇胺之化性，建構二氧化碳/醇胺之薄膜吸收系統，針對不同模組系統之實驗操作，並建構數學理論的研究，找出最適化的薄膜模組設計之操作變因，以求得較佳的二氧化碳吸收效率。本研究的操作模組包括(1)平板型及套管型;(2)溝渠式平板型;(3)中空 纖維膜組;(4)螺旋式套管。本研究的模組設計特色在於增加擾流因子(溝渠式平板型)以及增加滯留時間(螺旋式套管型)來提升二氧化碳吸收效率，並利用醇胺捕捉混合廢氣中之二氧化碳，討論各參數對二氧化碳吸收效率的影響，來達到減少能耗與減低成本之經濟效益。以醇胺對二氧化碳之化學吸收作廣泛的討論，結果發現，不論是何種類型之吸收，增加液體的流率或減少氣體的流率皆能增加二氧化碳 之吸收效率，而各種濃度變化的趨勢，以期實驗所得之結果符合所提出的數學模型之正確性。此外，本研究亦建構數學模型的理論分析，求得模組之順流與逆流操作中，氣-液兩項的一維與二維之濃度分佈曲線，並進一步推導出二氧化碳/醇胺在系統中之平均濃度分佈和質傳係數，進而求得吸收效率等物理量之數學關係式，且佐以實驗結果，以驗證數學模型之準確性。最後將可獲得在不同的操作參數和設計參數之最佳化操作。 The sequestration of carbon dioxide (CO2) emitted from industrial flue gas streams is one of important measures to stabilize greenhouse gas concentrations in the atmosphere to fulfill the objective of UNFCCC. This project proposes an integrated system that utilizes membrane contactors for gas absorption in aiming to accomplish CO2 capture. The absorption efficiency of CO2 in ethanolamine (MEA) solvent system of a parallel-plate membrane contactor with both concurrent- and countercurrent-flow operations was investigated theoretically and experimentally to predict concentration distributions, mass transfer coefficient and gas absorption rates. A two-dimensional mathematical modeling for predicting the concentration distribution and total absorption rate was developed, and the analytical solution for the resultant partial differential equations is obtained using the separated variables method with an orthogonal expansion technique. An experimental system with CO2/N2 gas mixture and Amine solutions as absorbents divided with a PTFE (Polytetrafluoroethylene) membrane system is used as the gas absorption membrane modules to conduct CO2 absorption performance tests. The theoretical predictions of the absorption efficiency, total absorption rate, average Sherwood number and concentration distributions were presented graphically with the mass-transfer Graetz number, inlet CO2 concentration, and both gas feed and absorbent flow rates as parameters. Four types of membrane cartridges, namely the parallel-plate module, parallel-plate module with carbon-fiber channel, hollow fiber module and spiral helix, were proposed in the present study to conduct the CO2 absorption performances in each individual design of the membrane contactor systems. Moreover, the operating and designing parameters that affect the CO2 absorption performance will be investigated to conclude a set of optimal operating conditions for the proposed gas-liquid membrane contactor systems.[[sponsorship]]科技部[[notice]]補正完