| 摘要 |
<p>1494487 Drying sludge HOECHST AG 3 Dec 1974 [4 Dec 1973] 52316/74 Heading F4G [Also in Division B1] A method for drying sludge comprises bringing superheated steam into direct contact with the sludge and preferably a portion of the steam which corresponds to the amount of water evaporated from the sludge in the drying process is drawn off and condensed whilst the remainder is recycled back to the drier. As shown in Fig. 1 sludge is introduced into a drier 1, and steam is passed thereto from a heater 3. The steam passing from the drier is split into two streams and the aforesaid portion passes into a condenser 8. In the apparatus of Fig. 2 the sludge is pre-heated in a heat exchanger 13 which is heated by fluid from the steam condenser in the form of a waste heat boiler 21. A paddle mixer 14 then mixes moist sludge with dried sludge from a cyclone separator 17 in a ratio of 1 : 1 and the mixture passes to a grinding drying device 15 and a series connected conveying drier 16 through which steam from a generator 3 is passed. Dried material in the cyclone 17 which is not fed into the moist sludge travels through a bucket wheel 19 into a storage container. In a further embodiment the steam and sludge are fed together into a spray drier (Fig. 3, not shown). Incompletely burned gases formed in the drying process are led from the first condenser to the steam generator to be burnt therein. Various temperatures and pressures of the superheated steam are specified.</p> |
