Method and apparatus for drying granular materials

摘要

The present invention discloses a method and an apparatus for drying granular materials by submitting them to dielectric heating by means of electromagnetic waves such as microwave, high frequency, etc. The granular materials to be dried are heated to the prescribed temperature with electromagnetic waves under a reduced pressure of a range not producing any glow discharge and then dried to the prescribed moisture percentage while passing through a pressure reducing process of a vacuum of higher degree. An apparatus for it is provided with a reduced pressure drying tank (1) having an electromagnetic wave generator (2), a main drying tank (30) communicated with said reduced pressure drying tank (1), and suction air sources (20), (20') which are provided respectively in the reduced pressure drying tank (1) and the main drying tank (30).