Dust Particle Migration Velocity in Electrostatic Precipitation

The apparent migration velocity in an electrostatic precipitator (EP) is calculated on the assumption that the theoretical particle migration velocity is not a function of the distance between the discharge electrode and the collecting electrode (discharge distance). Recently it has been reported that experimental values of migration velocity are dependent upon the discharge distance. In order to clarify the relationship between this parameter and apparent migration velocity, particle migration velocity was studied taking into account both the charging and motion time constants. Average apperent migration velocity was newly defined, and was compared with experimental values. The results of these investigations may be summarised as follows : (1) A certain distance is necessarary for a particle to reach its theoretical migration velocity, and there are instances where this distance exceeds the discharge distance. (2) Under these conditions, the average migration velocity is proportional to the square root of the discharge distance. (3) Apparent migration velocity in the transitional range can be decided by the use of the average migration velocity, and experimental results agree well with values of average migration velocity.