Acoustic Agglomeration Of Fine Particles From WFGD

As China’s energy consumption continue increasing, pollution problem rised by fine particles is becoming a serious environmental problem. Particles from flue gas make an important contribution to fine particle pollution in China. It is difficult to remove fine particles effectively by conventional dust remover. Fine particles enwrapped with desulfurization reaction products will be formed after the wet flue gas desulfurization (WFGD). Numerical simulation of coagulation fine particles from the WFGD in acoustic field has been studied in this thesis.Orthokinetic and hydrodynamic are chosen as coagulation mechanism based on the existing acoustic agglomeration model in this study. Brownian coagulation kernel has also been considered simultaneously for accuracy of the computation. The initial particle size distribution of the numerical computation is confirmed between0.2μm and10μm, which is based on experimental measurement data of flue gas after the WFGD from plant station. Sectional arithmetic is developed to improve computation precision. With the developed sectional arithmetic, group size is connected to particle mass concentration to adjust group magnitude automatically. The simulation results show that improvement of frequency cannot lead obvious increase of total number decrement rate of fine particles while sound intensity level does. High sound intensity level is more effective on agglomeration of fine particles. Considering investment cost and particle’s mass concentration distribution, acoustic with frequency of1500Hz and sound intensity level of160dB is optimal.A cyclone agglomeration chamber is promoted based on the structure type of cyclone separator to improve dwell time and agglomeration efficiency of fine particles. Simulation result by computation method of The Euler-Lagrange shows that dwell time of particles with diameter1μm in the agglomeration chamber is1.2s when inlet velocity is12m/s.Euler two-fluid model and population balance model are coupled to simulate the agglomeration chamber. Reductions of particle number concentration in outlet and pressure loss due to the use of agglomeration chamber under various conditions are analyzed. The results show that reductions of particle number concentration on the outlet of the cyclone agglomeration chamber increase with improvement of frequency and sound intensity level; The inlet gas velocity has impact on agglomeration effect and flue gas volume that can be handled; Pressure loss due to the use of agglomeration chamber is low and has little impact on the flue gas system.