Agglomeration characteristics during fluidized bed combustion of salty wastewater

• Agglomeration is sensitive to operational parameters and salt contents.
• Low-melting eutectics are not produced until the bed temperature exceeds 700 °C.
• Al2O3 is most effective in the inhibition of agglomeration.
• Additives inhibit agglomeration through physical effects within 800 °C.
• Increasing additive amounts leads to better inhibition results on agglomeration.

Fluidized bed combustion is a well-established and widely used technology for treatment of combustible wastewater. However, agglomeration is always encountered in industrial practice when dealing with wastewater that is rich in alkali metals. The objective of this present paper is to illustrate the agglomeration behaviors during fluidized bed incineration of salty wastewater. Various operational parameters were presented, viz. salt content, bed temperature, fluidizing gas velocity, static bed height, bed materials, and different additives. On the basis of SEM/EDX and XRD analysis of agglomerate samples, the mechanisms of agglomerate formation as well as the inhibition mechanisms of agglomeration for different additives were also discussed. The results show that agglomeration is promoted by the increasing of salt content, bed temperature, bed height, particle size, and by the decline of fluidizing gas velocity. All the additives tested, including CaCO3, Al2O3, Fe2O3 and Kaolin, are effective to different extents in inhibiting agglomeration. Physical effects were found to be the main inhibition mechanisms of agglomeration when the bed temperature is below 850 °C. Moreover, better results were also observed with increasing of additive amounts.

Figure optionsDownload as PowerPoint slide