| Summary: | 碩士 === 國立成功大學 === 環境工程學系 === 105 === In recent years, fossil fuel has been widely used by human thus booming the economy. A great amount of carbon dioxide releasing from fossil fuel combustion causes the global warming. As a result, carbon dioxide capture and storage techniques are needed to solve this issue. Oxy-fuel combustion system is a carbon dioxide capture technology, contributing to higher capture efficiency due to concentrated CO2, decreasing processing cost, and easy alterations. This study used the water-quenched slag and the desulfurization slag as the sorbents. It not only reduces the cost of sorbent but also has a high calcium content that can highly absorb CO2 of the flue gas in a fluidized bed reactor system and increases the reutilization of the waste. Therefore, this study simulated oxy-fuel combustion condition to capture carbon dioxide with De-S and GGBS slags in a fluidized bed reactor system at high temperature.
Results of this study are summarized as follows：
1.With the increasing temperature both for empirical model prediction and experimental results, the minimum fluidized velocity of De-S and GGBS slags at various particle sizes have a decrease trend. However, the particle size and particle density of slags can influence the values of the minimum fluidized velocity at various temperatures.
2.According to the results of TGA analysis, De-S and GGBS slags react with carbon dioxide at various temperatures, weight change of the De-S slag is much higher than the GGBS slag.
3.Regarding to the various operating parameters such as temperature, water vapor, flow velocity and CO2 concentration, it can be found that an increase of the carbon dioxide concentration can significant impact the slags sorption utilization. When the gas velocity reaches minimum fluidized velocity, the sorption utilization sorption of the slags at various particle sizes will be the best. As the velocity becomes higher than minimum fluidized velocity, the slag sorption utilization decreases. The little water vapor for 5% can promote CO2 capture of slag at various particle sizes and excessive water vapor for 10% at various particle sizes affect pore structure.
4.The best operating temperature is about 600oC for the CO2 capture with De-S slag at various particle sizes; the best operating temperature is about 500oC for the CO2 capture with GGBS slag at various particle sizes. It can be found that De-S slags at various particle sizes for the CO2 capture are superior to the GGBS slags .
5.The pilot plant is 10 times the size of the laboratory set, conducting the capture of carbon dioxide from air and oxy-fuel combustion conditions. It can be found that the utilization of 150-300μm De-S slag at 600 oC is better than other temperature. The utilization of 150-300μm De-S slags for the capture of carbon dioxide from oxy-fuel combustion is higher than air combustion due to the increase in carbon dioxide partial pressure of the flue gas from oxy-fuel combustion.
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