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

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 °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 °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 NOx 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. Tem...