Patent EP-1217059-A1 (EP)
Inventor: GROSJEAN PHILIPPE
IPC: F23G7/00
Filed: 2000-12-22
Abstract: The process for the treatment of crushing residues and sludge, heats the residue to give a solid matter rich in cleaned carbon and a gas byproduct rich in hydrocarbons. The solid material is processed mechanically to extract metal matter and treated carbon, followed by heating which also disposes of the combustible gases. The final heat stage gives decontaminated cinders and an exhaust vapor. To process crushing residue and sludge, the material has a light granular fraction, with particles ≥ 13 mm. The sludges are from cleaning stations or from dredging. The heating stage is at a temperature to give a mass ratio of 1:1 between the cleaned carbon and the developed gas. The calorific value of the residues is 3500-4500 kcal/kg and of the sludge is 650-750 kcal/kg. The heat level is set to produce a gas with a calorific value of 6500-7500 kcal/kg and a cleaned carbon with a calorific value of 1000-2000 kcal/kg. The final heat stage has successive steps through at least one cyclone, at least one combustion chamber, at least one boiler, past an injection of lime, active carbon and at least one rod filter. The exhaust vapors from the heating stages are controlled to determine the concentrations of heavy metals, dioxins and furanes. The co-combustion of the carbon and the produced gas gives a mass ratio of 1:1 at a temperature of 1400 degrees C. The final temperature achieved is set according to the mass ratio of the sludge and the cleaned carbon, at a level of 1050-1250 degrees C or 1100 degrees C to give a mass ratio between the sludge and cleaned carbon of 5. An Independent claim is included for an assembly to process crushing residues and dredging sludge with a heating stage (13) to convert the light residues into a solid material rich in cleaned carbon, and a gas rich in hydrocarbons in a mass ratio of 1:1. A mechanical separation stage (16-19) separates a major fraction of metals present. A feed station (22-28) takes in dredging sludge, to be passed to a mixing station (20) to be mixed with the mechanically-cleaned solid material. The mixture is injected (32) into a high temperature rotary kiln (31), together with combustion air and a combustible gas to the burner. A twin-wall conveyor (33) takes the decontaminated cinders from the kiln, with indirect water cooling. The exhaust fumes from the kiln are scrubbed (36-40,47) before release (46,41) into the atmosphere, to retain the carried dust particles (42,43) and the calorific value of the exhaust fumes is exploited (44,45). Preferred Features: The metal separator has a 3 mm screen (16), followed by two crusher cylinders in a cascade configuration, preferably open at 500 microns m (17) and 250 microns m (18), for the crushed material to drop by gravity to a further 500 microns m screen (19). The feed station for the sludge has at least one hopper with an array of plungers. The cleaning system for the exhaust fumes has at least one cyclone (36) followed by a boiler (37) with an ante-chamber for post-combustion. The boiler is followed by a reactor to neutralize the fumes (38) and retain heavy metals by the injection of lime wash (40) and preferably active carbon (39). The output from the reactor is passed to a rod filter (47). The boiler is a vapor generator leading to a turbine (44), coupled to an alternator to generate electricity. The retained dust is carried by a mass conveyor with insulation (42) at the cyclone, boiler and filter, leading to a big bag disposal point (43).