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Abstract
Student ID: N9731013 Title of Thesis: Effect of CO2 concentration in flue gas and its temperature on syrup carbonation and impurities removal Total Pages:82 Name of Institute: National Pingtung University of Science and Technology Name of Department: Department of Environmental Engineering and Science Date of Graduation: June, 2010 Name of Student : Ching-Sheng Yeh Degree Conferred: Master Adviser : Dr. Kuo-Ching Chang
The Contents of Abstract in this Thesis:
The greenhouse effect has caused the atmospheric temperatures increase and climate change, in these recent years “conserve energy and reduce carbon emission” has become the new environmental protection issue among the industries. Therefore, the development and application of carbon dioxide emissions reduction technologies in processes has become an urgent mission among the industries. The approach includes process reuse and the enhancement in energy efficiency. Among these processes, the reuse of carbon dioxide requires to coordinate with the acid point after water dissolution. In alkaline industrial processes, the acidity is to be neutralized or removed before it may be considered as carbon dioxide reuse. The experiment was performed in sugar refinery of Taiwan Sugar Corporation to study the influences of the boiler’s flue gas temperature and CO2 concentration on the removal of impurities in syrup. Simulated flue gas was introduced into a saturated reaction tank, with the pH value of syrup at 11, to perform carbonation reaction, and the produced calcium carbonate removed syrup impurities. In the study, the effect of simulated flue gas temperature and syrup brix changes on carbonation reaction efficiency were pursued.
To understand the effect of flue gas temperature changes on carbonation reaction efficiency, the inlet temperature of carbon dioxide were initially set at 50℃, 60℃, 70℃, and 80℃ in the experiment. The result showed that when the inlet gas temperature was 50℃, the molar percentage of CaCO3 in the syrup reached the highest at 99.28. When the inlet gas temperature was 80℃, the CaCO3 molar percentage in the syrup was the lowest at 96.51. The experimental data was further conducted with field trials; when the flue gas temperature was 60℃ the best reaction condition was obtained where the CaCO3 molar percentage in the syrup for saturated tanks A and B were 77.38 and 99.22, respectively. When the flue gas temperature was 80℃, the reaction was the least favorable, resulting with the CaCO3 molar percentage in the syrup for saturated tanks A and B being 71.24 and 89.37, respectively. In order to further understand how the flue gas temperature changes affected the removal effect of syrup impurities, sample analysis was conducted for syrup color. When the flue gas temperature was 60℃, the syrup color condition was at its best at 1145IU, whereas at 80℃, the color was least favorable at 1418IU.
To understand how the syrup brix changes influenced the carbonation reaction efficiency, the syrup brix were set at 68 Bx°, 70Bx°, 72Bx°, and 74Bx°, respectively to conduct another experiment series. The result showed that when the syrup Brix was 68 Bx°, the reaction was the best with CaCO3 molar percentage in the syrup being 76.53 and 99.17 for saturated tanks A and B, respectively. The reaction was the least favorable at 74Bx°, resulting with a CaCO3 molar percentage respectively of 69.59 and 92.38. The results were then conducted with field trials. The results showed that the reaction achieved the best condition at 68 Bx°, where the CaCO3 molar percentage in the syrup for saturated tanks A and B were 77.63 and 98.67, respectively. The reaction was the least favorable at 74Bx°, resulting with CaCO3 molar percentage for saturated tanks A and B being 70.53 and 91.07. Sample analysis was conducted for the syrup color. The results showed that when the syrup brix was at 68 Bx°, the syrup color was at its best at 973IU, whereas the color was least favorable for syrup brix at 74Bx°at 1298IU.
In summary, when the flue gas temperature and syrup brix increased, the CaCO3 molar percentage in the saturated tank and syrup purity had a declining trend. It could be concluded that the changes of the flue gas temperature and syrup brix both had a significant effect on carbonation reaction efficiency and the removal of syrup impurities.
keyworks: flue gas, CO2, reduction, syrup, carbonation
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