Electrostatic precipitator migration velocity

It can be shown that for fine particles (dp < 10 (tm) in an electrostatic precipitator the migration velocity of the particle is usually much higher than the corresponding particle terminal velocity in the gravitational field. For this reason, fine particles are commonly separated by electrostatic precipitation. 

Electrostatic Precipitators The principles and operation of electrical precipitators are discussed in Sec. 17 under Gas-Sohds Separations. Precipitators are admirably suited to the collection of fine mists and mixtures of mists and solid particulates. Tube-type precipitators have been used for many years for the collection of acid mists and the removal of tar from coke-oven gas. The first practical installation of a precipitator by Cottrell was made on sulfuric acid mist in 1907. Most older installations of precipitators were tube-type rather than plate-type. However, recently two plate-type wet precipitators employing water sprays or overflowing weirs have been introduced by Mikropul Corporation [Bakke,/. Air Pollut. Control Assoc., 25, 163 (1975)] and by Fluid Ionics. Such precipitators operate on the principle of making all particles conductive wnen possible, which increases the particle migration velocity and collection efficiency. Under these conditions, particle dielectric strength becomes a much more impor-... 

Typical gas and migration velocities in electrostatic precipitators as used in the cement industry are listed in Table 10. These figures are based on a dust content of less than about 0.1 g/Nm (dry) in the cleaned gas. 

Table 10 Gas velocity and particle migration velocity in electrostatic precipitators for cement works...

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