| 摘要 |
<p>A vessel for expanding particles of polystyrene etc. in steam where the steam inlets comprise a series of interchangeable or masked orifice plates set in a false base or in a part of the vessel walls surrounded by a steam pre-entry collar. A screw feed system is described for introducing dense or pre-expanded beads, having one zone with long pitch flights and a wide throat feed hopper for accepting pre-expanded pellets, and a separate hopper further upstream along the screw to accept dense pellets where the screw flight pitch is less and a flight root collar controls the swept volume. Precautions are taken against pre-expansion of the feed by backflow of steam from within the main expansion chamber. Esp. for mfg. expanded polystyrene beads with batch densities varying from 10 to 100 kg./m3. by varying the rate of steam admission, while maintaining the steam inlet pressure at e.g. 0.02 bar gauge pressure to hold 100-105 degrees C, without local super heating. Suitable for a pre-expansion/post-expansion treatment cycle.</p> |
