Inhibition of agglomeration by calcium-based zeolite as bed material during the combustion of reed black liquor in fluidized bed

摘要

In this study, a series of reed BL combustion experiments were carried out in a lab-scale fluidized bed with calcium-based zeolite as bed material at ranging of temperatures from 700 to 900 degrees C. The objective of this work is to investigate the effect of calcium-based zeolite on inhibiting agglomeration. The mechanisms of inhibiting agglomeration as well as agglomeration formation were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) analyses of representative agglomerates. The results show that the reed black liquor (BL) is burned out more completely in fluidized bed above 800 degrees C. The increasing of combustion temperature can promote the agglomeration of bed material. The molten Na2O center dot 3SiO(2) produced in the combustion of reed BL is the main binder leading to bed agglomeration. The Na2O center dot 3CaO center dot 6SiO(2) (melting point is 1030 degrees C) produced by the reaction of Na2O center dot 3SiO(2) and calcium-based zeolite, contributes to the inhibition of agglomeration significantly. The defluidization does not occur within 4h below 900 degrees C in the experiments, which indicates that calcium-based zeolite has significant effect on inhibiting agglomeration. This work provides bases for industry application of straw BL using fluidized bed alkali recovery technology.