| 摘要 |
<p><PICT:1067199/C1/1> A floating cover for a tank containing gas-evolving materials such as a sewage sludge tank 10, comprises a dome 22 supported with its centre clear of the tank contents by an annular buoyancy chamber 32, gas being withdrawn (e.g. to a burner) through a conduit 29 and through a conduit 34, bonnet 36 and relief valve (not shown). If desired the bonnet 36 may also open into the tank. The dome comprises a sheet 22 reinforced by ribs 221 and is located by rollers 41 and vertical guide strips (not shown). The chamber 32 is formed by a wall 30 and cover 33, and may be sealed for pressurizing or may be vented at 35. One or more motor-driven mixers 23 each comprising a tube 24, bars 48 and deflector 28, are provided, counterweights 31 being employed if necessary. The mixing pattern is as shown in full or dotted lines according to the direction of rotation of the mixer. Stops 45 limit the descent of the cover. The tank 10, which is preferably circular, has a sludge feed pipe 13, treated material being withdrawn through an elbow 16 whose height is adjusted by rotating conduit 14. Residual sludge is withdrawn through conduit 15, and a bottom draw off (not shown) may also be provided.</p> |
