Abstract

A plant (1) for drying and solid state polycondensing a moisture-containing polymeric material (M) in granular form, comprising a conduit (2) for feeding the material to be treated in a longitudinal direction (L), at least one treatment zone (7) for treating the polymeric material, means (6) for blowing an inert gas into the conduit, radiating means (8) for emitting an alternating electromagnetic field in the radio-frequency band and comprising a plurality of applicators (9) located in correspondence of said treatment zone and external to the conduit in longitudinally offset positions; said applicators are connected to the terminals of an electromagnetic wave generator (10) and comprise pairs of opposed radiating elements (11, 11') which are adapted to generate an alternating electromagnetic field in the conduit; the pairs of radiating elements defining magnetic dipoles with opposite polarities along the conduit. Further claimed is a method of drying and solid state polycondensing a polymeric material in granular form obtained by polycondensation using the plant.

IPC Classes  ?

• B29B 9/16 - Auxiliary treatment of granules
• B29B 13/08 - Conditioning or physical treatment of the material to be shaped by using wave energy or particle radiation

Abstract

A device for generating an alternating radio-frequency electromagnetic field in a working area comprises an applicator for emitting the electromagnetic field , an oscillator for providing an alternate voltage (V RF) and electric current (I RF) having a predetermined value and frequency to the applicator, power supply means for supplying a substantially DC voltage (V CC) to the oscillator, control means for controlling the electrical parameters of the AC voltage, the AC current and/or the frequency provided to the applicator by the oscillator. The control means comprise an input port connected to the electric power network (N), a first electronic control circuit which is connected to the input port for substantially instantaneously varying the electrical parameters and instantaneous control of the field emission power, a second electronic control circuit) for regulating the oscillator. The first electronic circuit has an output connected to the power supply means. A plant comprises the device.

IPC Classes  ?

• A23B 2/08 - Preservation of foods or foodstuffs, in general by heating using irradiation or electric treatment using microwaves or dielectric heating
• H05B 6/48 - Circuits
• H05B 6/50 - Circuits for monitoring or control