Release of K and Cl and Emissions of NOx and SO2 during Reed Black Liquor Combustion in a Fluidized Bed

摘要

For predicting and relieving ash-related problems and harmful gas emissions during fluidized bed combustion, release of K and Cl and emissions of NOx and SO2 during reed black liquor (BL) combustion in a fluidized bed were investigated in this study. The effects of bed material (calcium-based zeolite and limestone) and bed temperatures (700-900 degrees C) were also studied. The results showed that higher temperature favored the K release for both calcium-based zeolite and limestone, and calcium-based zeolite caused lower K release due to the formation of K3Al(SO4)(3), KAl(SO4)(2), and K2O-Al2O3-SiO2 eutectic compounds. Cl was mainly released in the form of HCl above 700 degrees C. Moreover, high temperature facilitated Cl release for calcium-based zeolite, whereas it had a complicated effect on Cl release for limestone. Although higher temperature increased the NO emission for both calcium-based zeolite and limestone, limestone resulted in higher NOx emission due to the conversion of fuel N to NOx under CaO catalysis. Temperature had a slight effect on SO2 emission for calcium-based zeolite, whereas it decreased the SO2 emission for limestone. Reed BL combustion generated lower SO2 emissions with the help of Na2CO3 and K2CO3, and limestone resulted in much lower SO2 emission with the help of CaCO3 and CaO.