| Summary: | 碩士 === 國立成功大學 === 環境醫學研究所 === 97 === The objective of this study is to establish a new way for correcting gas-particle partitioning of dioxin in flue gas, to discuss its rationality and to know the real dioxin removal efficiency of air pollution control devices (APCDs) in the sinter plant. The two sinter plants investigated are equipped with electrostatic precipitator (EP) and selective catalytic reduction (SCR) system. Partitioning of dioxin between gas and particulate phases in flue gas of the two sinter plants are evaluated via stack sampling and analysis and used the dioxin concentration of EP dust as an adjusted factor. In addition, the prediction model of dioxin partitioning between gas and particulate phases in flue gas published by Chi and Chang (2005) is included in order to discuss further rationality of partitioning of dioxin between gas and particulate phases in flue gas. The results of the removal efficiency of EP show that the adjusted gas-particle partitioning of dioxin are positive (A: gas phase: 4.56%; particulate phase: 97.8%; B: gas phase: 63.3%; particulate phase: 97.3%). The removal efficiency of particulate phase of original (A: gas phase: -116%; particulate phase: 63.1%; B: gas phase: 46.0%; particulate phase: 57.5%) and adjusted gas-particle partitioning of dioxin are higher than gas phase. Because the temperatures of flue gas are out of de novo synthesis, dioxin wouldn’t be formatted in the flue gas. Therefore, the removal efficiency of EP of adjusted gas-particle partitioning of dioxin should be more rationality. In addition, the results of removal efficiency of SCR show that the dioxin removal efficiency of particulate phase of original gas-particle partitioning are higher than gas phase (A: gas phase: 39.9%; particulate phase: 85.5%; B: gas phase: 95.1%; particulate phase: -57.1%), but the results of removal efficiency of adjusted gas-particle partitioning are contrary (A: gas phase: 62.7%; particulate phase: 52.2%; B: gas phase: 65.5%; particulate phase: -272%). In the SCR, dioxins of gas phase are reacted on the catalyst with oxygen and are converted into harmless carbon dioxide and water. Therefore, the negative removal efficiency of gas phase of the original gas-particle partitioning of dioxin is not rational. The particle would be adsorbed/desorbed from catalytic surface in the SCR, and caused the removal efficiency of particle are 52.2% and -272% in the sinter plant A and B, respectively. Based on those results, the removal efficiency of adjusting gas-particle partitioning of dioxin should be more rational. After adjusting gas-particle partitioning of dioxin, the dioxin of flue gas are mostly distributed in gas phase (93~99%) in the two sinter plants investigated. The gaseous ratios of adjusted gas-particle partitioning of dioxin are higher than the predicted (76~99%) and the original gas-particle partitioning of dioxin (71~87%). Those differences may cased by the difference of temperature between flue gas and sampling device, the characteristics of particle (concentration and size distribution), and the type of applied APCDs. Therefore, it caused severe adsorption of gaseous onto particles while sampling and caused the mis-estimation of the predicted gaseous ratios. Overall, this study provides important references for the correcting method of gas-particle partitioning of dioxin in the sinter flue gas and effective evaluating the removal efficiency of APCDs.
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