Patent ID: 7654396

Claim:
A classifier comprising: a rotating fin executing a classification of solid particles on the basis of a centrifugal force; a tubular downward flow forming member provided in an outer peripheral side of the rotating fin; and a bowl-shaped recovery cone arranged in a lower side of said rotating fin and the downward flow forming member; a housing accommodating said rotating fin, the downward flow forming member and the recovery cone, in which a contraction flow region is formed between the housing and the recovery cone, a two-phase flow is constituted by mixture of said solid particles blown up through the contraction flow region from the lower side of the recovery cone and a gas, the particles in said two-phase flow are separated into fine particles and coarse particles by bringing the two-phase flow into collision with said downward flow forming member in an upper portion of said housing so as to form a downward flow, and thereafter conducting the downward flow to said rotating fin side, and the fine particles are taken out while passing through the portion between the rotating fins rotating together with the air flow, wherein a circulating swirl flow development suppressing portion for suppressing a development of a circular swirl flow generated at its position is provided in an upper side of said contraction flow region and at an outer peripheral position of said downward flow forming member in such a manner as to have a lower end portion in a side wall upper portion of said housing and have an upper end portion in an outer peripheral portion of the upper surface plate, and in the case that a distance from a side wall of said housing to said downward flow forming member is set to L, a horizontal width from the side wall of the housing to an upper end portion of said circulating swirl flow development suppressing portion is set to W, and a vertical height from said upper surface plate to a lower end portion of said circulating swirl flow development suppressing portion is set to H3, a ratio W/L is regulated to be equal to or more than 0.15: and a ratio H3/L is regulated in a range between 0.15 and 1.