本研究針對燃煤電廠及水泥廠進行汞質量流布與平衡調查，及其煙道氣之汞排放特性進行探討，並同時採集其製程副產物，用以深究循環經濟下，因燃煤電廠之設備操作影響汞之流向，而水泥廠接收不穩定汞濃度之飛灰做為再生物料使用，於此情形下之汞質量流布。本研究燃煤電廠之煙道氣汞濃度介於0.010 ~ 0.141 μg/Nm3之間，其中以元素汞為主要排放汞物種，且粒狀汞之排放濃度相對穩定，但粒狀物上的汞含量介於0.005 ~ 0.030 mg Hg/g PM，遠高於飛灰之汞含量。電廠中主要汞來源為煤炭，輸入超過98%之總汞輸入量，而海水平均貢獻1.4%之總汞輸入量；而汞主要以飛灰及脫硫海水為主要輸出形式，分別佔31.4% ~ 91.2%與2.33% ~ 63.4%。汞質量流布變化藉由飛灰之特性分析瞭解，飛灰之汞富集能力與其捕捉氯及硫之多寡有關，更進一步由煤炭氯之含量得知，氯高度限制飛灰之汞富集能力，因高溫下產生之HCl可直接與Hg0反應，但硫因為高溫含氧燃燒使得SOx生成，其與汞在吸附點位上為競爭關係，須將硫進一步轉化才能協助捕捉Hg0。水泥廠汞輸入主要以石灰石(17.4 g/hr)為主，其次為鐵渣(9.23 g/hr)，再者為煤灰(6.71g/hr)，由此可見煤灰的使用，改變了水泥廠汞輸入結構；而輸出以熟料為大宗，輸出流率為3.01 g/hr並佔總輸出之66.3%，而煙道氣之汞輸出為1.53 g/hr，佔輸出之33.7%。造成汞質量輸入/輸出之差距以及較低之汞排放濃度與係數(煙囪之汞排放濃度為4.78 μg/Nm3，汞排放係數為7.6 mg Hg/ton clinker)之原因，可能源自於飛灰具有較高之汞富集能力，並透過飛灰回流系統將汞留存於系統之中，因此若是電廠之汞輸出以飛灰為主，於其再利用過程中，將改變水泥生產系統之汞輸入結構，並增加汞輸入量(煤灰汞輸入占總輸入之16.4%)，值得進一步探討。;This study investigates the characteristics of mercury emitted from a coal-fired power plant and a cement plant. Also, the feeding materials and products of the processes are sampled to investigate how the circular economy affects the distribution and mass balance of mercury in the cement plant. For the coal fired power plant, the HgT concentration emitted from the stack ranges from 0.010 to 0.141 μg /Nm3 while the emission of HgP is relatively stable. The mercury content on the particulate matter ranges from 0.005 to 0.030 mg Hg/g PM, which is much higher than the mercury content in fly ash. The majority of mercury input is from coal, accounting for 98% of input and the rest is from seawater applied for SOx removal. The mercury output include fly ash and desulfurized seawater, accounting for 31.4% ~ 91.2% and 2.33% ~ 63.4%, respectively. The variation of mercury mass distribution is investigated by analyzing the characteristics of fly ash and the mercury enrichment of fly ash is related to the chlorine and sulfur contents. Due to the high operating temperature and the presence of oxygen, the chlorine would be transferred to HCl which can directly oxidize Hg0 or incorporate with fly ash to form Hgp, and sulfur would be oxidized to sulfur oxide which would compete for adsorption sites with Hg0. Reactions can change the characteristic of sulfur to assist capturing Hg0. As for the cement plant investigated, the main source of mercury input is limestone (17.4 g/hr), followed by iron slag (9.23 g/hr) and the third is fly ash from coal combustion (6.71g/hr). The use of coal-fired ash changes the mercury input structure of cement plant and also increases the mercury input. The output includes clinker (3.01 g/hr) and the flue gas (1.53 g/hr). The difference in mercury mass input/output and the low mercury emission concentration (4.78 μg/Nm3) and low mercury emission factor (7.6 mg Hg/ton) may be due to the fact that fly ash has a high mercury enrichment capability, and retains significant amount of mercury in the system through the fly ash recycling process Therefore, if the mercury output of the power plant is mainly fly ash, the mercury input structure in the cement plant system will change and the mercury input will increase (coal ash accounts for 16.4% of the total mercury input), and is worthy of further investigation.
