Characterizing the Emissions of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans from Secondary Aluminum Smelters

• Main Authors: Ya-Hsin Wang, 王雅馨
• Other Authors: Shui-Jen Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/39566959540026535193

碩士 === 國立屏東科技大學 === 環境工程與科學系 === 92 === Two secondary aluminum smelters (secondary ALSs) were sampled and measured for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) to investigate the congener profiles of PCDD/Fs in the stack flue gases and emission factors and emission rates from the stack flue gases. Each total five stack flue gases and one bottom ash and fly ash was sampled from these two secondary ALSs (A and B) during March 3~5, 2003 and January 27~29, 2004. Furthermore, five flue gas samples were sampled from the fore of the bag filter. Each sample was last for 2~3 hours. The results are as the follows. The PCDD/F I-TEQ concentration in the stack flue gases of A was 10.6 ng I-TEQ/Nm3. 1,2,3,4,6,7,8-HpCDD and OCDD were the most abound congeners in PCDDs while 2,3,7,8-TeCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,6,7,8-HpCDF and OCDF were the most abound ones in PCDFs. The mean PCDD/F emission factor was 536 μg/ton-feedstock (RSD: 44.5﹪), while the corresponding I-TEQ emission factor was 55.7 μg I-TEQ/ton-feedstock (RSD: 84.7％). The mean PCDD/F emission rate was 812 mg I-TEQ/hr (RSD: 73.6％). The PCDD/F I-TEQ concentration in the stack flue gases of B was 1.45 ng I-TEQ/Nm3. 1,2,3,4,6,7,8-HpCDD and OCDD were the most abound congeners in PCDDs while 2,3,4,7,8-PeCDF, 1,2,3,4,6,7,8-HpCDF, 2,3,7,8-TeCDF and 1,2,3,7,8-PeCDF were the most abound ones in PCDFs. The mean PCDD/F emission factor was 280 μg/ton-feedstock (RSD: 39.8﹪), while the corresponding I-TEQ emission factor was 40.4 μg I-TEQ/ton-feedstock (RSD:45.5％). The PCDD/F I-TEQ concentration in the stack flue gases of A was 7.3 times higher than that of B. It may be result from that the feedstock rate of A was 37.6 times higher than that of B, the intrinsic differences in their involved feeding materials, furnace operating conditions, and air pollution control devices (APCDs). The PCDD/F I-TEQ contents in the bottom ash and fly ash of A were 0.162 and 5.59 ng I-TEQ/g, respectively. 1,2,3,4,6,7,8-HpCDD, OCDD, 1,2,3,4,6,7,8-HpCDF and OCDF were the most abound congeners in bottom ash while 1,2,3,4,6,7,8-HpCDF and OCDF were the most abound ones in fly ash. The PCDD/F I-TEQ contents in the bottom ash and fly ash of B were 0.00761 and 0.172 ng I-TEQ/g, respectively. OCDD、1,2,3,4,6,7,8-HpCDF and OCDF were the most abound congeners in bottom ash while 1,2,3,4,6,7,8-HpCDF and OCDF were the most abound ones in fly ash. By comparing the PCDD/F congener profiles of bottom ash and fly ash, the fraction of PCDFs of fly ash was much higher than that of bottom ash. Furthermore, the PCDD/F contents of fly ash was higher than that of bottom ash. It reveals that de novo mechanism increases the PCDD/F contents of fly ash. The removal efficiencies of PCDD/Fs by bag filters of these two secondary ALSs (A and B) were 5.94﹪and 5.88﹪, respectively. The elimination of PCDD/Fs by bag filter is very limit. The characteristics of PCDD/F emissions from local secondary ALSs, which were established in this study could be an useful information for control PCDD/Fs in the future.