結合旋轉填充床中以氫氧化鈉捕捉二氧化碳及沉澱法後處理程序開發

過去一世紀中，溫室氣體濃度逐年上升，隨之而來災害，造成嚴重的生命與財產損失，因此碳減量等相關討論成為近年來不可忽視的議題。其中利用液態醇胺類吸收劑經化學反應吸收二氧化碳，是目前最接近工業化的碳捕集方法，但仍有黏度與氣液質傳阻力過大，導致吸收塔的整體吸收效率不佳、設備體積龐大，以及再生吸收劑能耗過大等問題待解決。為改善醇胺類吸收劑之缺點，本實驗採用氫氧化鈉強鹼溶液作為吸收劑，並利用旋轉填充床高質傳效率的特性，對二氧化碳進行化學吸收，以不斷補充氫氧化鈉及連續循環吸收的方式，維持吸收百分比直到水溶液中碳酸鈉成分接近飽和，再利用索爾維制鹼法產生之大量廢棄副產物氯化鈣，在幾乎不需消耗能源的情況下，將碳酸根離子沉澱成碳酸鈣。文中將探討溫度、吸收劑的添加頻率、劑量等變數對吸收百分比的影響，並在碳酸鈉濃度與反應產物純度兩者中取得平衡後，得出最佳之操作條件為：旋轉填充床轉速1500 rpm、氣體為流量3.2 L/min之10% 、吸收劑為1 L的1 M 氫氧化鈉溶液，液體流量300 mL/min並持續循環使用，在系統開始後，固定每20分鐘加入氫氧化鈉21.12 g，共十次，並於pH值下降至13左右時結束吸收，加入3.1 M之氯化鈣至碳酸鈉溶液中，混合物進行抽氣過濾及水洗純化後，分別得到濾液濃鹽水（26.1 wt%, pH 10.3）、濾餅碳酸鈣（295 g, 2.95 mole）。此程序利用價值相對低的原物料吸收二氧化碳，生產具經濟價值的產品，過程中既不耗費能源，由於循環使用吸收劑而不耗水，更沒有廢水汙染問題，同時有效地捕捉二氧化碳。

關鍵字

二氧化碳捕捉；旋轉填充床；吸收百分比；氫氧化鈉；氯化鈣

並列摘要

Over the last century, greenhouse gas concentration has increased year by year. This situation could cause disasters such as great loss of life and property. Consequently, discussions regarding carbon reduction became unignorable issues. Currently, the most close to commercial application method to capture carbon is to use liquid alkanolamines through chemical absorption. However, the disadvantages such as its viscosity, mass transfer resistance, large equipment size and high energy demand of absorbents regeneration are to be resolved. With the aid of the intensified absorber of the rotating packed bed (RPB), we proposed an RPB absorption by NaOH in continuous recycle operation and periodically adding NaOH to maintain high absorption performance until the sodium carbonate close to saturation. Then, calcium chloride, a mass waste byproduct by Solvay process, was added into the sodium carbonate solution. Thus the carbonate ions would precipitate into calcium carbonate and solution become almost saturated sodium chloride. This paper investigated the effect of temperature, frequency and the amount of NaOH addition on absorption percentage as well as the purity of sodium carbonate and NaCl. The optimal operating conditions were obtained as: RPB at 1500 rpm, for 3.2 L/min 10% and 1 L of 1 M sodium hydroxide solution, the liquid flow rate is 300 mL/min in a continuously recycled mode. Sodium hydroxide 21.12 g was added every 20 minutes up to ten times to maintain 85% absorption, then ended the absorption when the pH dropped to about 13. Subsequently, 3.1 M calcium chloride was added to the sodium carbonate solution for 20 minutes followed by filtration and washing. Finally, brine (26.1 wt%, pH 10.3) and calcium carbonate filter cake (295 g, 2.95 mole) were obtained in good purity. Thus, this proposed process has the advantages of low cost absorbent for carbon dioxide capture and some valuable by-products formed while maintaining good carbon dioxide absorption without energy consumption and wastewater pollution.

並列關鍵字

carbon dioxide capture ； rotating packed bed ； absorption ratio ； sodium hydroxide ； calcium chloride

參考文獻

Aroonwilas, A., Veawab, A. (2006). Integration of Capture Unit Using Single- and Blended-Amines into Supercritical Coal-Fired Power Plants: Implications for Emission and Energy Management. International Journal of Greenhouse Gas Control, 1(2), 143–150.

Google Scholar

Ban, Z. H., Keong, L. K., Mohd Shariff, A. (2014). Physical absorption of capture: a review. Advanced Materials Research, 917, 134-143

Google Scholar

Borhani, T. N., Wang, M. (2019). Role of Solvents in Capture Processes: The Review of Selection and Design Methods. Renewable and Sustainable Energy Reviews, 114,109299.https://doi.org/https://doi.org/10.1016/j.rser.2019.109299

Google Scholar

Chandra, A., Goswami, P., Rao, D. (2005). Characteristics of flow in a rotating packed bed (HIGEE) with split packing. Industrial Engineering Chemistry Research, 44(11), 4051-4060.

Google Scholar

Chen, H., Tsai, T.-C., Tan, C.-S. (2018). capture using amino acid sodium salt mixed with alkanolamines. International Journal of Greenhouse Gas Control, 79, 127-133.

Google Scholar

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結合旋轉填充床中以氫氧化鈉捕捉二氧化碳及沉澱法後處理程序開發

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