利用RSM及LCA建立轉爐石捕獲二氧化碳之最適化研究

Abstract

本研究於超重力旋轉填充床(RPB)及漿體反應器(Slurry reactor)中，利用煉鋼爐石進行進行二氧化碳之捕獲實驗，其中所使用之煉鋼爐石為中國鋼鐵公司提供之轉爐石(BOF)，利用反應曲面法結合生命週期評估以了解系統最適化；首先使用反應曲面法軟體Design-expert 7.1.6進行實驗設計，由於超重力旋轉填充床之操作條件為溫度、轉速和反應時間，故使用三變數三階層的Box-Behnken designs (BBD)方法，漿體反應器操作條件為溫度和反應時間，使用二變數三階層的Full three-level factorial designs方法，試驗在不同的操作條件下，對於爐石碳酸化之影響，並將反應後之產物透過熱重分析儀(TGA)進行分析，並可計算出轉爐石之捕碳量，最後將所得之實驗數據輸入Design-expert 7.1.6各可得一最適反應曲面，其中在超重力旋轉填充床的反應曲面中，最高的轉化率為92.8%，在漿體反應器的反應曲面上，最高的轉化率為56.7%；接著以生命週期評估軟體Umberto 5.5，結合國際資料庫Ecoinvent 2.0與實際盤查數據針對兩個反應器共11個情境進行生命週期評估，佐以衝擊評估方法ReCiPe 2008計算各情境之環境衝擊，最後利用敏感性分析及不確定性分析研究找出關鍵影響因子。結果發現，超重力旋轉填充床之最適化條件為：溫度65℃、反應時間30分鐘、純二氧化碳流量0.1L/min，有轉化率92.8%；影響系統最適化之敏感性因子為實驗中所費之加熱能耗。

In this research, the experiments of mineral carbonation were conducted in an RPB and a slurry reactor using the BOFS provided by China Steel Corporation (CSC). The goal of this research is to combine the methods of response surface methodology and life cycle assessment to evaluate the systematic optimization. The RSM software and Design-expert 7.16 was used for experimental design of an RPB and a slurry reactor. The experiments of RPB, including the variables of temperature, rotating speed and reaction time, were designed by 3-level-3-factor Box-Behnken design (BBD). In addition, the experiments of slurry reactor, including the variables of temperature and reaction time, were designed by 3-level-2-factor Full three-level factorial design. Then the carbonated products were analyzed by TGA. The CO2 capture capacity was input to Design-expert 7.1.6 in order to analyze an optimal response surface. The results of RSM showed that the highest conversions are 92.8% and 67% in the RPB and a slurry reactor, respectively. The software of LCA, Umberto 5.5, was used for 11 scenarios with database built-in, Ecoinvent 2.0, and the actual inventory data. The ReCiPe 2008 was selected as valuation system to determine the sensitivity factors by sensitivity analysis and uncertainty analysis. The system optimization using an RPB combined of environmental impact and carbonation conversion is under these operating conditions : temperature of 65 ℃, reaction time of 30 min, particle size less 88 μm, CO2 gas flow rate is 2.5 L/min, which conversion is 92.84%. According to the analysis, the main sensitive factor for the systems is the energy consuming in the experiments.