利用超重力旋轉填充床對都市垃圾焚化飛灰進行水洗及碳酸化以達穩定化和再利用

Abstract

本研究的重點是利用超重力旋轉填充床對都市垃圾焚化飛灰進行水洗以及碳酸化，使飛灰達到穩定化並進行再利用。本研究的目標包括，探究超重力旋轉填充床水洗去除飛灰中的氯鹽的效果；利用RPB在捕集二氧化碳的同時，對飛灰進行碳酸化並研究其動力學；對於碳酸化後的飛灰作為膠凝材料，進行水泥取代以達到再利用的效果，並研究水泥砂漿的性質特徵。針對溫室氣體減量這一世界性的環境目標，以都市垃圾經焚化爐燃燒後所得的飛灰殘渣進行二氧化碳的捕集，研究證明超重力旋轉填充床技術可以很好地進行二氧化碳吸附，通過超重力旋轉床可將液體切割為更小的液滴，能更高效地進行反應，超重力焚化飛灰的碳酸化程序最高碳酸化程度可達到89.66%，捕碳容量約為0.253 kg /kg飛灰反應後水體的酸鹼值可降至6.07左右，提高超重力旋轉填充床的轉速可提高碳酸化轉化率。同時，碳酸化進程中所包含的水洗過程可高效地溶出飛灰中所含的可溶性氯鹽於水體中，可使固體中所含氯鹽降低83.85%。由於飛灰的主要組成成分與波特蘭水泥接近，且毒性溶出分析符合相關標準。本研究針對碳酸化反應後的飛灰添加水泥砂漿進行水泥取代，飛灰的添加對水泥的需水量及凝固時間都有一定的影響，且均符合標準。碳酸化後的取代樣呈現較好的抗壓強度，在取代率為5%時呈現較好的抗壓強度。

This study focused on the use of a rotating packed bed (RPB) for wet extraction and carbonation of municipal solid waste incinerator (MSWI) fly ash to stabilize and utilize. The objectives of this study include evaluating the extraction efficiency of chloride from MSWI fly ash with RPB; capturing CO2 during the carbonation process of fly ash and confirming the reaction kinetics by RPB; replacing cement by carbonated fly ash. MSWI fly ash was selected as feedstock in this research due to its high calcium content and high CO2 capture capacity. The optimal conversion of fly ash by experiment was 89.81% with a capacity of 0.253 kg-CO2 per kg-fly ash. The results showed that rotating speed of RPB can increase carbonation efficiency significantly. Meanwhile, the extraction process contained in the carbonation process can efficiently dissolve the 83.85% soluble chloride salt from fly ash. In this study, fly ash after carbonation reaction was used to replace cement. The replacement of fly ash has certain influence on the water demand and setting time of cement, but all meet the standards. The compressive strength of cement replaced by carbonated fly ash was higher than the cement replaced by fresh fly ash in all curing age, which revealed the best strength at a substitution ratio of 5%.