Influence of a combined external field on the agglomeration of inhalable particles from a coal combustion plant

The removal of inhalable particles less than 2.5 μm in diameter, generated from coal combustion plants, presents a serious challenge in air pollution abatement. These particles can penetrate deep into the lungs and are difficult to remove by cyclones, electrostatic precipitators, and other conventional separation devices. This work studies the combination of acoustic fields and gas–solid jet action on inhalable particle agglomeration. SEM images of aerosols with and without the combined fields demonstrate that the inhalable particles are removed by the formation of large aggregates. The removal efficiency using these combined fields is up to 45.4%. The large particles entrained in the jet enhance the agglomeration of the inhalable particles. Furthermore, the inhalable particles have an optimum agglomeration size distribution at 1416 Hz. For gas–solid jets, gas turbulence energy encourages particles to collide with acoustic wave excitation; combined fields are beneficial for commercial industrial applications. With increasing jet velocity, the removal efficiency initially increases and then decreases. Maximum removal efficiency occurs at a 25 m s− 1 jet velocity. The use of different relative humidities (RHs) permits highly efficient mass removal for particles smaller than 2 μm or greater than 9 μm in diameter.