| 摘要註: |
本研究主要針對添加硝酸鈣、碳酸鈣及氧化鈣，在不同操作條件下，對流體化床焚化爐床質結塊去流體化，及重金屬截留與逸散之影響。最初，先探討在不同操作溫度(700℃、800℃、900℃)、操作氣速(U/Umf= 1.1、1.3、1.5)、床質粒徑(0.545 mm、0.770 mm、0.920 mm)及鈉金屬濃度(0.5%、0.7%、0.9%、1.1%)下，床質結塊去流體化時間，與添加鈣化物後，床質結塊去流體化時間比較，發現當添加鈣化物後，床質結塊去流體化時間明顯延長，且三種鈣化物中，硝酸鈣延緩燒結能力最為明顯，氧化鈣延緩效果較低。 而重金屬被截留於床質中之多寡，主要由床質石英砂吸附重金屬之能力影響。由實驗結果發現，床質對鉛、鉻、鎘之吸附效率，分別為鉻>鉛>鎘，且當添加鈣化物時，由於鈣化物可延緩結塊去流體化發生，維持床質良好之流體化品質，使床質可大量吸附重金屬，故可提升床質截留重金屬之總量，其中，在某些操作條件(如900℃、0.545 mm、0.5%鈉濃度)，焚化操作時間過長或過短，鈣化物延緩效用較不明顯之情形下，以碳酸鈣及氧化鈣截留較多重金屬，其餘條件下，硝酸鈣有較佳重金屬截留量。 而飛灰重金屬逸散濃度高低，主要由重金屬本身揮發性之高低，及床質截留重金屬多寡，有較大之關係。鉛、鉻、鎘其揮發性由高至低，分別為鎘>鉛>鉻，故鎘於氣相中之逸散濃度為三者中最高。當添加鈣化物後，由於提升床質截留重金屬之效果，故間接減少重金屬後續逸散問題，其中，以硝酸鈣減少重金屬逸散濃度之效果最佳。 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. |