- 學位論文
旋轉填充床中氫氧化鈉/氫氧化鈣吸收二氧化碳之程序—原位吸收劑再生及循環
Carbon Dioxide Capture by Sodium Hydroxide/Calcium Hydroxide in a Rotating Packed Bed with in situ Regeneration and Recycling
摘要
隨著工業迅速發展，對於環境負荷日趨沉重，溫室效應已是目前迫切須改善的問題，目前已有許多文獻利用單乙醇胺(MEA)、MDEA、PZ等醇胺類吸收劑進行化學吸收二氧化碳之研究，其特點為吸收容量大且反應速率快，但面臨的缺點大致有以下幾點: (1)廢氣煙道中的SO2、NO2及O2易引起醇胺降解；(2)吸收劑再生所需的能耗大；(3)高黏度；(4)所需的設備體積大。 本研究利用旋轉填充床的高質傳特性，以氫氧化鈉及氫氧化鈣溶液為吸收劑，進行化學吸收二氧化碳之實驗，另一方面，藉由連續添加氫氧化鈣於原體系，使其產生苛化作用(Caustification)以進行吸收劑再生與副產物碳酸鈣的分離程序，並且將化學再生後的吸收劑重複進行吸收程序，為一循環系統；文中將探討操作溫度、氣液流量、吸收劑之濃度等變數對於吸收百分比、表徵總括氣膜質傳係數(KGa)以及經長時間操作後對整體系統之效益影響。 實驗結果顯示，當氫氧化鈉水溶液中含有氫氧化鈣時，由於兩個鹼的協同作用能有效提升其與CO2反應之效益，使吸收效果提升，再者，藉由於原體系中之碳酸化作用(碳酸鈣沉澱)，能夠呈現理想的程序特性，包含: (1)氫氧化鈉能於原體系中再生；(2)能使吸收劑維持高鹼性利於CO2捕獲；(3)簡易的副產物碳酸鈣與吸收劑分離程序。 除此之外，實驗經過數小時的連續操作後仍可維持其吸收效益，同時能夠容易地將副產物碳酸鈣收集並且再利用，此程序實現了對環境友善，低耗水以及能有效捕捉二氧化碳的概念。
並列摘要
Global warming has become a widespread concern in recent years, especially CO2 emission. Although several absorbents and processes have been proposed for carbon dioxide capture, the critics remains in the absorption efficiency and economical feasibility. Alkanolamines such as monothanolamine (MEA), methyldiethanolamine (MDEA), piperazine (PZ) have been the well accepted absorbents over the years for CO2 capture process. However, there are several drawbacks associated with these processes, including (1) amine degradation by SO2, NO2 and O2 in the flue gases requiring absorbent makeup, (2) high energy demand of absorbent regeneration, (3) high viscosity, and (4) large equipment size. In this study, a rotating packed bed (RPB) that could dramatically improve mass transfer efficiency and, leading to high reaction rate between absorbent and CO2 should be considered. Also, a very inexpensive absorbent which is sodium hydroxide together with calcium hydroxide in aqueous solution was proposed. On the other hand, a continuous CO2 capture process by calcium hydroxide addition was demonstrated, in which the absorbent, aqueous sodium hydroxide, was in-situ regenerated and almost completely reused. The gas flow rate, liquid flow rate, rotating speed and the concentration of the absorbent were taken into consideration as operating variables to observe the influence on absorption percentage, apparent overall volumertric mass transfer coefficient (KGa) and the efficiency of the process. According to experimental results, high absorption efficiency was noted due to a synergic effect from these two alkalines. Moreover, in-situ carbonation (precipitation of calcium carbonate) presented some very desired process traits including (1) easy/in-situ regeneration of sodium hydroxide, (2) stabilizing pH suitable for CO2 capture, (3) easy storage and separation of final product. Furthermore, the promising CO2 capture process could keep high absorption efficiency and pH value even after serveral hours operation. Meanwhile, calcium carbonate could be easily collected as a by-product of commercial value. Thus, this process achieved the concepts of eco-friendly, low water consumption, and zero waste together with effective carbon dioxide capture.
參考文獻
延伸閱讀
- 李德威（2016）。旋轉填充床中氫氧化鈉甘油水溶液吸收二氧化碳〔碩士論文，國立臺灣大學〕。華藝線上圖書館。https://doi.org/10.6342/NTU201601757
- 卓明君（2008）。變壓吸附法濃縮及回收氣化產氫製程中二氧化碳與氫氣之模擬〔碩士論文，國立中央大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0031-0207200917353701
- Pan, S. Y. (2011). 在超重力旋轉填充床中利用煉鋼爐石碳酸化反應進行二氧化碳捕捉 [master's thesis, National Taiwan University]. Airiti Library. https://doi.org/10.6342/NTU.2011.01529
- 戴侑霖（2010）。水合作用改質氧化鈣捕獲溫室二氧化碳氣體之循環再生能力研究〔碩士論文，國立交通大學〕。華藝線上圖書館。https://doi.org/10.6842/NCTU.2010.00390
- 傅守璽（2010）。Low Pressure Hydrogen Annealing in Improving Electrical and Optical Properties of In-line Sputtered Gallium and Aluminum Co-doped Zinc Oxide Films〔碩士論文，崑山科技大學〕。華藝線上圖書館。https://www.airitilibrary.com/Article/Detail?DocID=U0025-2107201014545200