PURPOSE: To draw out particles in a fluidization activation furnace in a short time without allowing the particles to remain on a perforated plate by presetting size of a bowlshaped cap put on the upper part of a hollow center pillar, numerical aperture in the specified region of the perforated plate and the inclined angle thereof respectively.

CONSTITUTION: A perforated plate 6 is positioned to the center part for dividing the inside of a furnace into two parts and fixed to the upper part of a hollow center pillar 2 having an inflow port of particles in the upper part and an inversed bowlshaped cap 5 is put on the vertex of the center pillar. The inner diameter of the cap 5 is regulated to 1.2W3 times of the outer diameter of the center pillar and in the perforated plate 6 positioned in the under side of the cap 5 in the interval of 5W50mm, the numerical aperture in a range within 1.2W1.5 times of the other diameter of the cap in the center side is regulated to 1.2W3.0 times in comparison with the other part and the perforated plate is fixed so that it has inclination of 2W10° toward the center piller fixing part. Furthermore the hollow center piller 2 is covered with a steam jacket 8 to pass steam for cooling and also the outer side is wound with a refractory insulator 9 to prevent heat radiation.