Single screw extruder being based on the so-called barrier

A spray dryer device for spray drying a sample dissolved in an organic solvent is disclosed, comprising a circulation line in which an inert gas is circulated by a blower, a heater for heating the inert gas to a specified temperature, a main drying chamber provided with a spray nozzle through which the sample dissolved in the organic solvent is sprayed into the inert gas, a collector in which the powdered sample produced in the main drying chamber is collected, and a condenser in which the gaseous organic solvent is condensed and recovered. The powdered sample is obtained in this spray dryer device for spray drying organic solvents by spraying the organic solvent through the spray nozzle into the main drying chamber in which the oxygen concentration is held to a low value by the introduction of the inert gas.

The spray dryer device for spray drying the sample dissolved in the organic solvents is designed to obtain samples in powder form by spraying a sample dissolved in an organic solvent through a nozzle into a drying chamber.

In recent years, single screw extruder being based on the so-called barrier screw concept have gained acceptance to an increasing extent. In a so-called barrier screw, the screw channel is divided in a solid matter channel and a melt channel by way of a further side bar. Compared with the primary side bar, being known from conventional screws, the smaller formed barrier side bar allows a transverse flow of melt from the solid matter channel into the melt channel. The cross-section of the melt channel increases in a downstream direction whereas the cross-section of the solid matter channel continuously decreases in the downstream direction as to maintain the desired conveying effect of the screw. Due to the so-called barrier zone particularly the heat transfer from the barrel and the screw surface to the granulate not yet melted is improved.