Mechanistic Influence of Chemical Agglomeration Agents on Removal of Inhalable Particles from Coal Combustion

Abstract

Particle pollution has been a research topic attracting the attention of the researchers around the world because inhalable particles are hazardous to humans and the environment. The major resource of particle pollution is the combustion of coal and biomass. Dust collectors, electrostatic precipitators, and bag filters are required to remove particles from flue. Because of the large specific surface areas of inhalable particles, they easily agglomerate to form larger aggregates; therefore, improving the capture efficiency of dust collectors is of importance. Herein, chemical agglomeration agents were sprayed into a turbulent agglomeration chamber to improve the removal efficiency of inhalable particles. The results showed that the total removal efficiency of inhalable particles was 59.2% for the three-composition agglomeration agents of kappa carrageenans/Tween-80/NH4Cl (KC/TW/NH4Cl). The mean particle diameter increased from 2.8 μm before agglomeration to above 10.0 μm after agglomeration. In the agglomeration process, nonionic TW accelerates the wetting properties, in which the polymer, KC, or anion polyacrylamide, promotes prolongation of the contact time between droplets and particles. Two different removal mechanisms are proposed to explain the effect of chemical agglomeration agents. Immersion agglomeration described the agglomeration process of only fine particles, and distribution agglomeration supported the capture of large particles for fine ones in polydispersed aerosols.