Efficiency of heat transfer and thermal expansion of tubular heat exchange members in an indirectly heated rotary heater

摘要

Recycled asphalt product is heated within an indirectly heated recycled asphalt product heater by passing heated gases through heat exchange members within a drum while the recycled asphalt product is moved through the drum from one end to the other end of the drum. The heat exchange members provide conduits for the heated gases, the conduits extending from an inlet adjacent a source of heated gases to an outlet communicating with an exhaust, each conduit following a looped path and having two or more segments each with a longitudinal length extending from adjacent one end of the drum to adjacent the other end of the drum. The segments are arranged serially in a serpentine configuration, are generally parallel to one another, and are spaced apart radially within the interior of the drum. Each inlet is coupled with the source of heated gases for longitudinal movement of the inlet relative to the drum along an inlet site adjacent the source of heated gases, and each outlet is connected to the drum for affixing the outlet against longitudinal movement relative to the drum at an outlet site adjacent one of the ends of the drum. The configuration and orientation of the conduits enable longitudinal expansion and contraction of the conduits in response to heating and cooling of the conduits, while the outlets remain essentially stationary at the outlet site.