Chi Kai Hsien, Chang Shu Hao, Chang Moo Been
Graduate Institute of Environmental Engineering, National Central University, Chungli 320, Taiwan.
Environ Sci Technol. 2008 Mar 15;42(6):2111-7. doi: 10.1021/es702396y.
Previous study indicates that the polychlorinated dibenzo-p-dioxin and -dibenzofurans (PCDD/F) concentration measured in the stack gas of the Waelz plant investigated reached 194 ng-TEQ/(N m3) (TEQ = toxic equivalence), due to the relatively high potential of PCDD/F formation and a low PCDD/F removal efficiency (<70%) achieved with the baghouse filter (BF). In September 2006, the Taiwan government setthe PCDD/F emission limit for existing Waelz plants as 1.0 ng-I-TEQO/(N m3). The retrofit technology for reducing PCDD/F emissions from the existing Waelz plant was evaluated at the same time. Carbon-type adsorbent injection technology was adopted in early 2006 to reduce the emission of dioxin-like compounds at the Waelz plant investigated. Flue gases and ambient air samplings were conducted during the two stages of retrofit to evaluate the removal efficiency of dioxin-like compounds at the Waelz plant investigated. At stage 1, by applying adsorbent injection + single baghouse filter (SBF), the PCDD/F and polychlorinated biphenyl (PCB) concentrations measured in the stack gas at the Waelz plant were 4.62 ng-TEQ/(N m3) and 0.08 ng-TEQ(WHO)/(N m3) (TEQ(WHO) = World Health Organization TEQ), respectively, as the adsorbent injection rate was controlled at 40 kg/h (or 540 mg/ (N m3)). At stage 2, the PCDD/F and PCB concentration measured at stack gas, achieved with adsorbent injection + dual baghouse filter (DBF) system, were further reduced to 0.235 + 0.04 ng-I-TEQ/(N m3) (I-TEQ = International TEQ) and 0.004 + 0.002 ng-TEQ(WHO)/(N m3) with the adsorbent injection rate at 16 kg/h (or 215 mg/(N m3)). In the meantime, the atmospheric PCDD/F concentrations measured in the vicinity area of the Waelz plant were greatly reduced from 568-1465 to 48.9-130 fg-I-TEQ/m3. Higher removal efficiency (>99.8%) achieved at a lower adsorbent injection rate (16 kg/h) of the adsorbent injection + DBF system also significantly reduced the total PCDD/-F and PCB emission flows (per kg of electric arc furnace dust treated) to 1925 ng-I-TEQ and 30.5 ng-TEQ(WHO), respectively.
先前的研究表明，在所调查的韦尔兹工厂的烟囱气体中测得的多氯二苯并 - 对 - 二噁英和多氯二苯并呋喃（PCDD/F）浓度达到了194纳克毒性当量/（标准立方米）（TEQ = 毒性当量），这是由于PCDD/F形成的可能性相对较高，并且采用布袋除尘器（BF）实现的PCDD/F去除效率较低（<70%）。2006年9月，台湾政府将现有韦尔兹工厂的PCDD/F排放限值设定为1.0纳克国际毒性当量/（标准立方米）。同时对降低现有韦尔兹工厂PCDD/F排放的改造技术进行了评估。2006年初采用了碳型吸附剂注入技术来降低所调查的韦尔兹工厂中二噁英类化合物的排放。在改造的两个阶段进行了烟气和环境空气采样，以评估所调查的韦尔兹工厂中二噁英类化合物的去除效率。在第1阶段，通过应用吸附剂注入 + 单布袋除尘器（SBF），在所调查的韦尔兹工厂烟囱气体中测得的PCDD/F和多氯联苯（PCB）浓度分别为4.62纳克毒性当量/（标准立方米）和0.08纳克世界卫生组织毒性当量/（标准立方米）（TEQ（WHO） = 世界卫生组织毒性当量），此时吸附剂注入速率控制在40千克/小时（或540毫克/（标准立方米））。在第2阶段，采用吸附剂注入 + 双布袋除尘器（DBF）系统时，烟囱气体中测得的PCDD/F和PCB浓度进一步降至0.235 + 0.04纳克国际毒性当量/（标准立方米）（I - TEQ = 国际毒性当量）和0.004 + 0.002纳克世界卫生组织毒性当量/（标准立方米），吸附剂注入速率为16千克/小时（或215毫克/（标准立方米））。与此同时，在韦尔兹工厂附近区域测得的大气PCDD/F浓度从568 - 1465大幅降至48.9 - 130飞克国际毒性当量/立方米。在较低的吸附剂注入速率（16千克/小时）下，吸附剂注入 + DBF系统实现了更高的去除效率（>99.8%），这也显著降低了PCDD/F和PCB的总排放流量（每处理1千克电弧炉粉尘），分别降至1925纳克国际毒性当量和30.5纳克世界卫生组织毒性当量。
