| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 88 === Among the methods of separating CO2 from flue gas such as physical absorption, physical adsorption, chemical absorption and membranes separation, the most general and economic way is the chemical absorbent method which amines is commonly used. We need to add the equipment of separating CO2 after the wet scrubber of separating acid flue gas such as SOx, NOx and HCl and it will increase the difficulty in operating and the cost of present industrial plants. In this study, we investigated the efficiency of separating SOx and CO2 from the flue gas simultaneously using wet scrubber that is commonly used control equipment for flue gas desulfurize for small industrial plants in Taiwan. Besides, the semi-continuous flow experiment has been done to estimate the cost.
We made a small-scale spray tower to investigate its absorption of CO2 solely and the simultaneous absorption of CO2 and SO2 by NaOH solution. The experiments were conducted under following conditions: the concentration of NaOH solution 0.1~5N, L/G ratio 7.5~12.5 L/m3, operating temperature 30~50oC, CO2 concentration 10%~20% (v/v) and SO2 inert concentration 0~700ppm.
The results show that the highest removal efficiency of CO2 is 39.3﹪that were obtained at concentration of NaOH solution of 2N for continuous-flow experiments. The removal efficiency of CO2 increases with liquid to gas ratio (L/G ratio) and temperate. However, the concentration of CO2 has slight influence of removal efficiency of CO2.
There is only little decrease in the removal efficiency of CO2, and the removal efficiency of SO2 is greater than 80﹪in all the experiments on simultaneous absorption of CO2 and SO2. The highest removal efficiency of CO2 is 35.3% obtained at NaOH concentration of 2N. As the liquid to gas ratio increases, the removal efficiency of CO2 and SO2 increase. The removal efficiency of CO2 and SO2 also increases with operating temperature. When concentration of CO2 is increased, the removal efficiency of inflow CO2 increase, but the removal efficiencies of SO2 decrease slightly.
According to the continuous flow and the semi-continuous flow experiments on the simultaneous absorption of CO2 and SO2 into NaOH solution, the estimated cost of NaOH for practical application is about 3,600~6,000 N.T./ ton CO2. If this estimated cost is compared with the total cost of capital and operation of a new system, the system of simultaneous control of CO2 and SO2 investigated in this study would be more economic and practical.
Keywords:CO2、SO2、Absorption、NaOH
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