Method and apparatus for bulk material treatment

DETAILED DESCRIPTION Surprisingly it has now been found that contrary to the treatment theories usually held in the art hitherto, the intensity of drying in the case of pasta can be greatly increased without harm if, according to the invention, the individual particles or pieces of bulk material are turned and displaced relatively to one another during treatment.
According to the use proposed by the present invention, it is provided that the pasta pieces are kept freely in motion in the drying air relatively to one another and relatively to the air flow, preferably with formation of a throughflow fluidised bed.
In contrast to the stationary treatment employed hitherto, the use of which in pre-drying has been accepted almost as a dogma, even with a first test apparatus it was found that moving treatment made possible an unexpected improvement as regards intensity and correspondingly as regards the dimensions of the installation.
Preferably the pre-drying includes at least one treatment stage, of which at least one, namely the first treatment stage, takes place in a fluidised bed.
Thus when drying pasta it is possible to dispense with the shaker pre-dryer i.
e.
the crust formation on the outer surface practised hitherto, thus providing better conditions for the drying work as a whole.
If the first stage of the pre-dryer operates with a throughflow fluidised bed, the mechanical stressing of the pasta pieces is so slight that their shapes are retained even without prior surface crusting.
In other words, the freshly pressed pasta article has sufficient strength for subsequent drying.
Surprisingly, the throughflow fluidised bed which has been used in almost all branches of industry for decades has been found to be the best solution.
By a throughflow fluidised bed there is meant not simply blowing through a bed of material.
In the technical world "fluidised bed" denotes a state of affairs wherein the air forces are approximately as great as or greater than the gravitational forces acting on the particles of bulk material