Acoustic coagulation of fine particles from WFGD

The objective of this study is employing acoustic coagulation to induce agglomeration of fine and ultrafine particles after wet flue gas desulfurization (WFGD) and analyzing its effectiveness and characteristic based on numerical simulation. Matters such as calcium sulfate and calcium sulfite in WFGD can form very fine particles. Smoluchoski's equation is employed as the simulating model. Orthokinetic coagulation, hydrodynamic coagulation and Brownian coagulation are taken into account to form the agglomeration kernel. An improved sectional arithmetic is introduced to achieve sectional size adjusting automatically according to the mass concentration of particles, so that section size is fine where the mass concentration is large to guarantee computational accuracy, but coarse where the mass concentration is small to save computation time. Besides, mass conservation rate is introduced to estimate the calculation error in the compute of mass concentration. Simulation results show that the overall number concentration decreased more than 40% after acoustic wave acting on the flue gas for 2 second; Increasing sound intensity level (SIL) is more effective to coagulation than increasing frequency; There exists an optimal acoustic wave frequency within 1500~2000Hz; Coarse particles are more sensitive to acoustic wave frequency than fine particles.