Drying hopper and powder drying method using the same

摘要

Disclosed is a drying hopper comprising, disposed in its lower position, a cone portion having diameters gradually decreasing toward a lower end thereof, in which a high temperature gas is injected toward powder descending in the cone portion to thereby dry the powder, wherein said drying hopper comprises a cone portion 11 having a slant, circular wall, said cone portion 11 having a plurality of vertically spaced rows of nozzles 20, formed through the circular wall, disposed at predetermined intervals in a circumferential direction of the circular wall; a plurality of vertically spaced ring-like shells 21 fluidtightly attached to an external surface of the circular wall of the cone portion 11 with interstices therebetween in positions such that said plurality of rows of nozzles 20 are respectively, at gas inlets thereof, covered by said plurality of ring-like shells 21; and a plurality of gas feed pipes 22 respectively connected to said plurality of ring-like shells 21 in communicating relationship. By virtue of this drying hopper, powder, e.g., polyethylene powder, can be dried to a solvent content as small as 20 ppm by weight or less by low cost, simple operations.