| 摘要 |
A rotary drum dryer (12) has devices for cooling shielding flights (44) located in the combustion zone of the drum. The devices comprise cooling flights (46) which rotate with the drum to scoop up relatively small amounts of virgin aggregate from aggregate accumulated in the lower portion of the drum and to shower this aggregate over the outer radial surface of the shielding flights (44) upon further rotation of the drum, thereby cooling the shielding flights without substantially decreasing the mean temperature of the aggregate. Cooling efficiency is enhanced by the continuous cascading of fresh aggregate over the shielding flights from the cooling flights (46) through a substantial portion of the drum's rotation. The cooling flights and shielding flights preferably cooperate to limit or even prevent the showering of materials into the burner flame (24) and thus inhibit burner flame quenching and accompanying emissions. Particularly preferred cooling flights take the form of auxiliary flights which can be easily adapted to existing shielding flight designs.
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