In the concentration of materials, e.g., a solution of polymers, by discharging the material from an expansion nozzle into an evaporating chamber, the degree of the concentration is increased so that the concentrated material is no longer fluid. Such operation is made feasible by disposing screw conveying means in the discharge of the evaporating chamber for withdrawal of the material. Efficiency of the concentration is increased. The material can be further concentrated in evaporating chambers through which the conveying means carry the material.
The discharge apparatus comprises an at least four-shaft screw pump having engaging shafts (1,2,3,4) which rotate in opposite directions in pairs. The viscous product to be processed is caught up over a large area and removed by the screws. A double shaft screw pump is connected downstream of the actual collection zone as a pressure build-up zone. The two center screws (2, 3) of the collection zone merge equiaxially into the screw shafts (2a, 3a) of the pressure build-up zone. The collection zone and the pressure build-up zone are combined into one constructional unit. At least one screw shaft is driven. The resulting high viscosity product strands (7) are caught up by the screws in the collection zone and are moved on into the pressure build-up zone. The double shaft screw pump is used for the build up of a high operational pressure and thus provides the prerequisite for the subsequent connection of further procedural stages. The universal possibilities of use of this discharge apparatus are to be stressed in particular.
