The effects of calcium compounds on agglomeration/defluidization and emission of heavy metals in the fluidized bed incineration

• Main Authors: Ming-Chih Tsai, 蔡明智
• Other Authors: Chiou-liang Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/93318045524892433792

碩士 === 國立高雄大學 === 土木與環境工程學系碩士班 === 99 === The major objective of the study focuses on the effect of Ca(NO3)2, CaCO3 and CaO, inhibit the generation of agglomeration, and control the heavy metals (Pb, Cr, Cd) emission in different operation conditions. First, comparing the defluidization time, weather the calcium compounds in the wastes or not, in different fluidized parameters, including temperature (700℃, 800℃ and 900℃), gas velocity (U/Umf = 1.1, 1.3 and 1.5), sand particle size (0.545 mm, 0.770 mm and 0.920 mm) and the concentration of Na (0.5%, 0.7%, 0.9% and 1.1%). The results indicate that addition of Ca inhibit agglomeration significantly, and increase the defluidization time, and Ca(NO3)2 has the best inhibition ability. Second, the fluidized medium (silica sand) can absorb a high proportion of heavy matals in the incineration process; in addition, the extent of absorption ability follows the sequence: Cr>Pb>Cd. The results indicate that when add the calcium compounds to the wastes, it can inhibit the generation ofagglomeration, and maintain high quality of the fluidization, so it can increase the amount of heavy metalsin the silica sands. On the other hand, when the ability of inhibition agglomeration significantly by adding the calcium compounds, Ca(NO3)2 increasing the quantity of heavy metals in the silica sand are the best; otherwise, CaO and CaCO3 are better than Ca(NO3)2. Finally, the volatility of heavy metals and the amount of heavy metals by the silica sands absorbed, are influenced the heavy metals emission. The volatility of heavy metals follow the sequence: Cd>Pb>Cr, so Cd has the highest concentration in the gas phase. Furthermore, add the calcium compounds to the wastes, increasing the quantity of heavy metals in the silica sands, so it can help decrease the emission concentration of the heavy metals, and Ca(NO3)2 has the lowest emission concentration.