Removal of fine particles from coal combustion in the combined effect of acoustic agglomeration and seed droplets with wetting agent

The characteristics of the interaction between fine particles and droplets in acoustic field were investigated experimentally in an acoustic agglomeration chamber. A novel technique to promote fine particles removal in the coupling effect of acoustic field and seed droplet with wetting agent was presented. The results showed that fine particle removal efficiency in the acoustic field correlates well with the wettability of wetting agent. As the relative contact angle decreases from 83 degrees to 0 degrees, fine particle removal efficiency increased by 18% at the sound pressure level (SPL) of 150 dB. The stage removal efficiencies with primary alcohol ethoxylate (JFC) and fluorinated surfactant (FS-310) solution droplets addition were close to those with water droplets addition in the acoustic field, but the stage removal efficiencies with sodium dodecyl sulfonic salt (SDS) and modified polysilanol surfactant (Silanol w22) solution droplets addition were much higher than those with water droplets addition. Particles can be separated effectively in acoustic field with wetting agent droplets addition, especially in a low intensity acoustic field. The removal efficiency was increased by 25% with SDS solution droplets addition than without droplets addition in acoustic field at the SPL of 130 dB. The wettability of fine particle surface was changed by wetting agent, making the coagulation processes irreversible in acoustic field. Therefore, fine particle removal efficiency was highly improved in the combined effect of acoustic wave and wetting agent solution droplets. (C) 2015 Elsevier Ltd. All rights reserved.