| 摘要 |
<p>The pneumatic conveying system is used where continuous flow is required, e.g. in tunnels where packing or stopping material has to be supplied fast and continuously over lengthy periods to ensure successful packing or sealing. The seals (5) at the top and bottom of the filling bunker are switched in a sequence, which ensures that they always operate when no material is in flow and thus are not exposed to wear. The switching sequence starts with the top gate open, and the filling screw feeds material into the bunker until the level gauge signals full. The screw is halted, the gate closed and the control valve opened. This operates the bottom gate seal (5) and the screw feeder (6) to fill the surge or buffer bunker (7), and thence via screw (8) into the blow-line (9). Compressed air is supplied (10) when the feeder screw (8) starts, and the bunker is emptied down to the lower gauge (4).</p> |
