| 摘要 |
<p>In a heat-proof tank is a rotary cylindrical drum on whose periphery are 2, 3 or more pairs of needles or radially projecting points, parallel and side by side in rows along the whole periphery. Each pair supports a pebble conveyed by a belt, which projects its downstream end between each pair of needles. The belt is in the horizontal plane through the drum axis. The sense of rotation of the needles brings the pebbles first upwards, then onto the opposite curve and down to where an endless belt against the drum prevents them from falling; they slide finally on to a conveyor which removes them from the drier. The hot air stream from below remains particularly in the upper zone, due to valves within the drum and suitably actuated.</p> |
