The Effects of Submicrometer Dust Charging and Coagulation on ESP Efficiency by Using Alternating Electric Field

Although submicrometer dust of 0.01-1 ?m is a great hazard to the human being and the environment, the collection efficiency of which by using an electrostatic precipitator is still low at present. The high density ions (1.97 × 10 9 cm -3 ), which are produced by the synergistic effect of the high gas particle momentum of 9.82 × 10 -22 g ·m ·s -1 in the flue and ionized in the strong electric field, provide many ions for submicrometer dust charging and coagulation. In this paper, the new method of homopolarity submicrometer dust coagulation in an alternating electric field was investigated. The experimental results showed that in the conditions of reduced alternating electric field strength of 7 Td and frequency of 100 Hz, for a median particle size of 0.2-?m silicon powder, the mass percent of particles of < 0.2 ?m decreased from 71% to 53%. The changing rate was 25.4%, whereas the mass changing rate of the particles of 5-10 ?m increased by 1.62 times. For a median particle size of 6-?m talcum powder, the mass percent of particles of < 0.2 ?m decreased from 22% to 11%. The changing rate was 50%, whereas particles of 5-10 ?m increased by 18%. The experimental results showed that the coagulation in an alternating electric field will be an effective method to collect submicrometer dust in high velocity flow field.