System for drying moist sludge

Abstract

A system of drying moist sludge includes a drier as a main component. The drier is composed of a lower gas fluidizing section and an upper high speed fluidizing section. Moist sludge to be be dried is introduced into a mixer in which each particle is coated with the moist sludge, and the coated particles are supplied to the gas fluidizing section. Fine particles flown away from the gas fluidizing section are fluidized in the high speed fluidizing section while they are dried by heating elements. After completion of the drying operation, dried sludge particles are collected in a dust collector. Subsequently, fine dried sludge particles are conducted to a bag type dust collecting unit from which they are discharged to a sludge hopper. A part of the coarse dried sludge particles collected in the dust collector is supplied to the gas fluidizing section, a part of the same is supplied to the mixer to be mixed with moist sludge, and the balance is delivered to the sludge hopper. The gas exhausted from the bag type dust collecting unit is introduced into the gas fluidizing section as fluidizing gas. A part of the exhausted gas is extracted to the outside by a quantity substantially equal to that of the gas vaporized from the moist sludge.