Drying drum for used asphalt granules - having injection unit allowing carefully zoned heating in counter-current using diverse lifting flights for heat transfer by rotation from upwardly slanting gas jet avoiding overheating, blue smoke emission and asphalt cracking

摘要

The drum (1) dries recovered asphalt granules in counter-current by a form of indirect heating. The drum has various fittings in functionally classified regions, which resemble, e.g., lifting and mixing flights. In the novel design, an externally-produced hot gas stream is directed by an injection unit (2) to heat the upper internal drum wall and flights in the heating region (I). The absorbed heat energy is delivered to the rolling granules as the drum rotates. Gravity keeps the rolling granules in the lower regions, away from the hot gas jet. Cooled gases leaving a sec. heating region (II) blow through a deluge of asphalt granules, hence preheating them.