A part of fine particles with average size of 2.5 μm in the atmosphere is directly or indirectly coming from the emission of coalfired thermal power plants

the disposal of particles with size 10 μm and 2.5 μm through electrostatic precipitator（EP）

in large-scale coal-fired power plants

however

is yet short of quantitative analysis data at present.Hence

field test has been carried out in flue gas duct before and after the EP of one 200 MW unit

obtaining the concentration of fly ash particles

particle size distribution

and staged dust removal efficiency of the EP.Study shows that the effectiveness of EP for removal particles with size greater than 10 μm to be good

but the dust removal efficiency to be rapidly decreased for particles with size less than 5μm

the dust removal efficiency only to be 90% for particles with size of 2.5μm.thus

resulting in emission of considerable amount of small particles into the atmosphere environment.