Impact of CaO and CaCO3 addition on agglomeration/defluidization and heavy metal emission during waste combustion in fluidized-bed

In this study, CaO and CaCO 3 were used as additives to investigate the inhibition of agglomeration/defluidization and adsorption of Pb and Cd. The results showed that defluidization time may be prolonged when CaO or CaCO 3 is added to the artificial waste. Before defluidization, Pb and Cd emissions were not intensified significantly in the existence of Na; however, after defluidization, the emission of Pb and Cd increased significantly. The heavy metal emission concentration was lower when CaO or CaCO 3 was added to the artificial waste than when only Na was added. CaCO 3 showed a stronger defluidization inhibition effect because of the longer defluidization time. For different parameters, the heavy metal emission concentration appeared to decrease with an increase in the operating temperature; however a change in the gas velocity did not affect the heavy metal emission. In addition, an increase in the bed material size considerably reduces the defluidization time. A small bed material size is more favored as the large specific surface area in this case allows for the adsorption of a greater amount of heavy metal and more efficient mixing with waste.