Patent ID: 7880109

Claim:
A classification apparatus comprising: a pair of electrodes including a first and a second electrodes opposed to each other to generate an electric field for classifying charged fine particles according to electric mobility to form a classification region, the first electrode attracting the charged fine particles; a sheath gas supply portion for supplying a non-charged gas as a sheath gas to the classification region from one end of the classification region; an aerosol supply portion having an introduction port provided on the second electrode side and on the upstream side in the sheath gas flow for supplying a charged aerosol through the introduction port; a larger-size particle discharge portion having a discharge port provided on the second electrode side and on the downstream side in the sheath gas flow for discharging charged fine particles having particle sizes larger than a predetermined particle size among the classified charged fine particles in the charged aerosol together with part of the sheath gas; and an outlet provided on the other end side of the classification region and downstream of the larger-size particle discharge portion in the sheath gas flow for discharging remaining charged fine particles together with the sheath gas, thereby removing the remaining charged fine particles having particle sizes smaller than the particle sizes of the particles removed by the larger-size particle discharge portion.