Experimental study on aggregation of PM10from coal combustion by magnetic seeding in uniform magnetic field

Aggregation experiments on fly ash particles in the size range of 0.023-9.314 μm from Dongsheng bituminous coal combustion were conducted by magnetic seeding in a uniform magnetic field. The modalities of the aggregates between magnetic seeds and fly ash particles, and the influence of particle size, magnetic flux density, particle residence time and mass concentration on aggregation were examined. Experimental results showed that the fly ash particles are connected by magnetic seeds. Removal efficiencies of all sized particles can be increased by magnetic seeding, which is more obvious for the smaller particles. The aggregation by magnetic seeding can be enhanced by increasing the magnetic flux density, the particle mass concentration, the particle residence time in magnetic field and the mass ratio of magnetic seeds to fly ash, so that total particle removal efficiency is raised. When particles are saturatedly magnetized, the increase in magnetic flux density has no effect on particle aggregation. Keeping the mass ratio of magnetic seeds to fly ash, the particle number median diameter decreases with increase in the total particle removal efficiency, and keeping other conditions constant, the rising of the mass ratio causes an increase in particle number median diameter. Numerical simulation results indicated that the total particle removal efficiency attains 80% and particle number median diameter decrease from 0.151 μm to 0.098 when particle mass concentration is 40 g·m-3.