- 學位論文
煙道氣之二氧化碳捕捉： 氨水吸收法 vs. 單乙醇胺吸收法
Carbon Dioxide Capture of a Stack Gas: Aqueous Ammonia Absorption vs. Monoethanolamine Absorption
摘要
工業革命以來，最緊迫的環境議題之一是減少人為二氧化碳排放和降低大氣中的溫室氣體濃度。其中二氧化碳是造成地球溫室效應最主要的氣體，因此二氧化碳捕獲技術也成為各國科技發展的主要方向。 本研究針對淨輸出功率為550 MWe的燃煤發電廠所排放之廢氣，其組成為13.50 mol% CO2、15.17 mole% H2O、68.08 mole% N2、2.43 mol% O2及0.82 mol% Ar，溫度為57.2℃、壓力為103 kPa，分別比較氨水（NH3·H2O）和單乙醇胺（C2H7NO）兩種溶劑對二氧化碳的吸收能力及能耗多寡。模擬結果顯示，氨水及單乙醇胺皆可吸收99.9 mole%的二氧化碳；耗能方面，氨水吸收劑每吸收莫耳流率13.49 kmol/hr的二氧化碳需要5,695 kW的能量，單位換算後，每吸收一噸二氧化碳需要34.64 GJ，單乙醇胺吸收劑每吸收莫耳流率13.49 kmol/hr的二氧化碳需要4,001 kW的能量，也就是每吸收一噸的二氧化碳需要24.26 GJ，所以單乙醇胺吸收劑能耗較少。值得一提的在嗅覺閾值的控制方面，吾人必須再添加一座吸收塔使得氨氣排出濃度小於5.75 ppm，單乙醇胺所排出濃度小於2.6 ppm，結果顯示，MEA比氨氣需要更多的水，以達到環保法規的要求。 本論文使用 “Aspen Plus”進行程序合成與設計，程序流程圖則使用“visio”繪製。
並列摘要
Since the Industrial Revolution, one of the most pressing environmental issues is to reduce anthropogenic carbon dioxide emissions and reduce greenhouse gas concentrations in the atmosphere. Because carbon dioxide is the main gas that causes the global greenhouse effect, the carbon dioxide capture technology has become a main research direction worldwide. The design basis of this study deals with the emissions from a coal-fired power plant with a net output of 550 MWe. The exhaust gas consists of 13.50 mol% CO2, 15.17 mole% H2O, 68.08 mole% N2, 2.43 mol% O2 and 0.82 mol% argon at a temperature of 57.2℃ and 103 kPa. To compare with the absorption capacity of carbon dioxide and energy consumption, we used aqueous ammonia and monoethanolamine, respectively. The simulation results showed that both aqeous ammonia and monoethanolamine are able to absorb 99.9 mole% of carbon dioxide, removing more than 90% of the carbon dioxide in the flue gas. In terms of energy consumption, the ammonia stripper requires 5,695 kW with the molar flow rate of 13.49 kmol/hr of carbon dioxide. That is, the absorption of one tonne of carbon dioxide requires 34.64 GJ. As to the monoethanolamine stripper requires 4,001 kW with the same molar flow rate of 13.49 kmol/hr of carbon dioxide. That is, the absorption of one tonne of carbon dioxide requires 24.26 GJ. As a result, we conclude that the energy consumption is relatively smaller with the monoethanolamine absorbent. It is worth noting that in order to control the emission odor, we must add another absorption tower so that the ammonia discharge concentration is less than 5.75 ppm and the concentration of monoethanolamine less than 2.6 ppm. The results showed that monoethanolamine requires more water than aqueous ammonia in order to meet environmental regulations. In this thesis, the software “Aspen Plus” was used to carry out the synthesis and design. The process flow diagrams were drawn using the software “visio”.