- 學位論文
以中空纖維管狀薄膜接觸器進行二氧化碳吸收之模擬與實驗探討
Simulation and experimental study on carbon dioxide absorption using hollow fiber membrane contactor
摘要
本研究主要以實驗探討與模擬預估探討於管狀薄膜接觸器進行二氧化碳之捕獲程序，首先驗證模擬預估與實驗是否相符，由於模擬預估與實驗結果為吻合，因此以理論模式進一步探討膜管中的徑向與軸向之二氧化碳濃度分布和膜管長度對於二氧化碳吸收通量之影響，並在實驗中探討物理和化學吸收與混合醇胺類對於二氧化碳捕獲之影響。 本實驗研究中以商業化PVDF中空纖維管狀薄膜接觸器來進行二氧化碳之捕獲，使用純水及不同反應速率之醇胺類吸收劑進行探討，選擇二胺基二甲基丙醇（AMP），並添加不同濃度的無水二次乙亞胺（PZ）作為活化劑，並發現在物理吸收中，液體體積流速的上升會使二氧化碳的吸收通量增加，但不隨著氣體體積流速改變而有明顯變化，而在化學吸收當中，則跟物理吸收有相反的結果，會隨著氣體體積流速上升而使二氧化碳的吸收通量增加，液體體積流速改變只有稍微增加；去除率則隨氣體體積流速上升而下降，而液體體積流速上升只有稍微變化，可發現當有添加PZ之AMP水溶液吸收劑因其二氧化碳的負載量跟反應提高而使整體的二氧化碳吸收通量上升。 由模擬驗證可知模擬預估與實驗結果相符，並利用其理論模式深入探討管狀薄膜接觸器之二氧化碳的濃度，模擬結果可見在徑向之二氧化碳幾乎在液-膜表面就完全就被反應，在軸向中可見當在低氣體體積流速時，氣體在膜管的滯留時間長，因此二氧化碳的濃度變化極大，而當氣體體積流速提高時，氣體在膜管的滯留時間縮短，而導致二氧化碳的濃度變化不大，並模擬縮短和增長膜管對於吸收通量之影響，可知膜管長短對二氧化碳的濃度變化很大，因此可利用模擬來找到最佳的模組去操作二氧化碳之捕獲。
並列摘要
The carbon dioxide capture processes using tubular membrane contactor with physical and chemical absorption was investigated experimentally and theoretically in the study. First, simulation results were compared with experimental data to confirm the feasibility of the simulation program. Then the carbon dioxide concentration profiles in the tubular module, the distribution of carbon dioxide flux and the recovery were simulated to study the effect of gas flow rate, liquid flow rate, mixed amines solution and tubular length etc. on the absorption performance. A commercial PVDF hollow fiber membrane contactor was used for carbon dioxide capture experiments. Distilled water and amines absorbent 2-Amino-2-Methyl-1-Propanol (AMP) with different concentrations of Piperazine (PZ) as the activator were used for preparing absorbing solution. Experimental results from physical absorption showed that the absorption flux of carbon dioxide increase with liquid volumetric flow rate, but the gas flow rates only give a slight effect on the absorption rate. When carbon dioxide was captured by chemical absorption, the absorption rate is enhanced significantly and the effect of gas volumetric flow rate on absorption flux is more significant impact than that by liquid flow rate. Removal fraction of carbon dioxide decreases with the increase of gas flow rate, while the liquid flow rate only gives a slight effect. Simulation results in chemical absorption showed that the carbon dioxide was almost completely reacted in the region very close to liquid- membrane surface. The gas flow rate and membrane length are playing important roles in the carbon dioxide concentration profile in the axial direction of gas phase. It can be concluded that the simulation process can be used for determining the better module length and operating conditions for carbon dioxide capture.