The invention relates to an apparatus for conditioning of bulk material, such as shavings or chips, especially of the vegetable type, such as wood-chips, for the production of fibers or pulp for making paper or cardboard or making fiberboards.
It is known to produce the pulp necessary for paper-making by a process in which wood chips or other vegetable substances are used. These wood chips, which can be approximately 20 to 40 mm long and up to approximately 20 mm wide, are defibered, so as then to be processed further in the appropriate way. To achieve as high a fiber quality as possible, the wood chips can be conditioned in a silo by means of low-pressure or high pressure steam.
The conditioned bulk material is discharged by means of a clearing unit through one or more orifices provided in the silo bottom, via screw conveyors, and is delivered to the defibration mill. During interruptions in operation, for example, during operating faults and the like, blockages in the silo occur as a result of the swelling of the wood-chips. Such agglomerations can be eliminated only by knocking, poking, etc. Moreover, the bulk material tends to form bridges, with a result that the discharge of the material from the silo becomes irregular and can even be blocked completely. Also, the temperature of the wood-chips is uneven and is unsatisfactory in view of the subsequent process steps. Considerable steam losses occur as a result of the formation of bridges and channels in the bulk material. Another disadvantage is that, because of the irregular steam distribution or varying retention time, the wood-chips change irregularly and their properties are thereby impaired, so that during subsequent use problems of quality can arise and additional costs are incurred.