| 摘要 |
PCT No. PCT/DK91/00175 Sec. 371 Date Feb. 8, 1992 Sec. 102(e) Date Feb. 8, 1992 PCT Filed Jun. 27, 1991 PCT Pub. No. WO92/00250 PCT Pub. Date Jan. 9, 1992.A method and a system serve to completely or partially dehydrate sludge by evaporation which originates from e.g. sewage. The sludge is dried with addition of heat in a drying chamber (2), the sludge being transported on an endless travelling grate (3) from an inlet opening (8) in the drying chamber (2) to a discharge opening (9) in it. The sludge is deposited on the grate in a plurality of juxtaposed sludge strings (18) by means of an extruder (6), in which the sludge is preheated to almost 100 DEG C. prior to extrusion. The extruded strings (18) are then heated with such an intensity that the water in the sludge immediately begins to boil, and that a zone of preferably saturated water steam is formed at any rate in the immediate vicinity of the sludge. This provides a light and porous, dried sludge product which is in no way either burnt or scorched, and which constitutes excellent fuel as well as excellent compost. The system has a simple and compact construction and is inexpensive to produce, just as it works at moderate operation costs. |
