Patent ID: 8651032

Claim:
A classification device comprising: a stationary classifier having a cylinder shape and hung down from a device top portion; a rotary classifier disposed inside the stationary classifier; a cylindrical deflection ring hung down from the device top portion between the stationary classifier and the rotary classifier to form a downward flow; a rectifying cone having a downward convexly curved cone shape and disposed under the stationary classifier; and a classification zone outer circumference housing which covers a classification zone composed at least of the stationary classifier, the rotary classifier, the deflection ring, the rectifying cone; the rotary classifier including a large number of rotary fins arranged in a circumferential direction, each rotary fin having a length direction of a plate facing a vertical direction and disposed at an arbitrary angle with respect to a direction of a center axis of the device, characterized in that: the stationary classifier includes stationary fin groups attached multistageously and each having a plurality of stationary fins disposed annularly with respect to the center axis of the device, each of the stationary fins being inclined down toward the direction of the center axis of the device; an inclination angle of each stationary fin is limited to a range of 50° to 70° with respect to a horizontal direction; a setting pitch P between the stationary fins and a width L of each stationary fin in a direction of particles flowing are combined so that a value of P/L is in a range defined by an upper limit line P/L=0.042×(θ−50)+0.65 in a range 50°<θ<70°, a lower limit line P/L=0.4 in a range 50°<θ<60° and a lower limit line P/L=0.019×(θ−60)+0.4 in a range 60°<θ<70° where θ is an inclination angle of each stationary fin, P is the setting pitch between the stationary fins in a multistageous direction, and L is the width of each stationary fin in the direction of particles flowing; when an ascending solid-gas two-phase flow composed of a mixture of solid particles and a gas enters between the classification zone outer circumference housing and the stationary fin groups and passes between the stationary fins inclined down, the solid-gas two-phase flow collides with surfaces of the stationary fins and changes into a downward flow so that coarse particles with large mass on this occasion fall down toward the rectifying cone side located in a lower zone while solid particles not falling down are carried with an air flow and flow toward the deflection ring and rotary fin side, and a ratio of Vmax and Vave (Vmax/Vave) is set to be no larger than 2.5, where the Vmax is a maximum flow velocity of a rotary fin inlet flow velocity and the Vave is an average flow velocity thereof.