US 6,978,725 B2 · Process and apparatus for treating biogenic residues, particularly sludges

Abstract

The invention relates to a process and apparatus for treating biogenic residues, particularly sludges, preferably in the area of a clarification plant. Biogenic residues with a variable dry substance are subjected to aerobic drying until an energy-independent thermal treatment can be carried out. During the drying process, evaporated water is discharged in an odor-free condition without releasing freely volatile components, the dried sludge is intermediately stored a number of times and then utilized in preferably a number of successive thermal treatment steps. The two-stage cleaning of the stream of waste gas includes a dust collection unit and an adsorption unit. The waste heat is recycled through a heat exchanger to generate heat and electricity. The apparatus for carrying out the process includes a wet sludge storage container (1), a low temperature drying system (2), storage containers (3, 5) for intermediate storage of the dried biogenic residues, and a thermal treatment system with one or more thermal treatment steps (7, 8). Cleaning of the flue gas takes place preferably by means of a primary cleaning step (10) and a secondary cleaning step (11) for adsorption, for example, with clarified water. Energy recovery (9) from the hot waste gas is ideally carried out before the flue gas cleaning.

Claims20

Dependent claims

Process for treating biogenic residues, particularly sludges, preferably in the area of a sewage treatment plant, characterized by the following process steps:

(a) Collecting biogenic residues with variable dry substance content followed by aerobic drying in a temperature range up to a maximum of 60–70° C.;
(b) Maintaining the drying step until reaching a level of drying of the biogenic residues which permits energy-independent utilization;
(c) Discharging with the moist stream of air only the amount of water evaporated during drying without the release of freely volatizing compounds;
(d) storing the dried material in primary intermediate storage, particularly for equalization of different drying stages;
(e) storing the dried material in a secondary intermediate storage as a buffer;
(f) thermally treating the material in a number of successive thermal treatment steps;
(g) discharging residues of the treatment from each of the thermal treatment steps;
(h) Cleaning the streams of material arising during thermal treatment in primary and secondary cleaning steps, the material stream being filtered in the primary step, especially by means of dust collection, and by adsorption of the stream in the secondary cleaning step;
and
(i) recovering energy from all material streams brought out of the process by conducting the energy to a heat transfer medium.

7 more elements

Dependencies are inferred from the claim text.

Process and apparatus for treating biogenic residues, particularly sludges

Life of this patent

Process and apparatus for treating biogenic residues, particularly sludges

Life of this patent

Abstract

Claims20