| 摘要 |
The counterflow drum mixer includes an elevated virgin aggregate inlet end and an opposite asphaltic product discharge end. A burner lies intermediate the ends and defines a combustion volume. Shield flights surround the combustion volume defining an annular chamber with the drum wall. Recycle material is supplied to the annular chamber at the upstream end of the combustion volume for heating by convection and conduction in the annular chamber. The virgin aggregate material flows through a drying zone, into the combustion volume and between the shield flights into the annular chamber for contact with and conductive heating of the recycle material. Radiant heat transfer from the combustion volume along radii of the drum to the annular chamber is prevented. Virgin aggregate and recycle material in the annular chamber is prevented from entering the combustion volume by the shape of the shield flights and the rotation of the drum which enables the virgin aggregate in the combustion volume to shield the recycle material from radiant heat. The combined virgin aggregate and recycle material is mixed with liquid asphalt in the mixing zone to form the asphaltic product.
|
