Furnaces – Process – Incinerating refuse
Patent
1992-12-14
1994-03-29
Favors, Edward G.
Furnaces
Process
Incinerating refuse
110229, 110236, 110238, F23G 700
Patent
active
052974960
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the combined treatment of waste materials of two types A and B. A being waste material having a relatively high energy content and B being a water containing waste material having a relatively low energy content.
It is known from DE-A 3635068 to pyrolyze waste material, in particular soil polluted with oil. This process is carried out at a temperature of 400.degree.-300.degree. C. The gaseous components produced during the pyrolysis are used as fuel gas. It is disclosed that with the process not only waste material and sludge from purification installations, but also waste oil and polluted soil may be processed at the same time. The just mentioned materials are first dried, gas is removed at a temperature of about 600.degree. C. and at a temperature above 1200.degree. C. the material is incinerated and brought into a ceramic form. The produced gas is first reduced in general by using a cokes bed, then washed and, subsequently, used as fuel. The residue of the pyrolysis contains cokes, which absorbs harmful substances such as heavy metals. By this absorption the residue is environmetally unharmful. During the after-combustion, which is performed after the pyrolysis, additives such as combustible materials or fly ash may be added in order to obtain an inert or ceramic product.
EP-A-0 168 532 and EP-A- 0 217 4433 discloses methods for processing sludges such as dredging mud, possibly mixed with industrial sludge, purification sludge and similar materials, or with powdery combustion residues such as fly ash, wherein the sludge is converted into a plastic mass by drying and/or mixing, said mass being brought into shape of individual pieces, which pieces are made to ceramic bodies by drying and baking. This drying and baking is carried out under oxidizing conditions and under a specific gradual increase of temperature. After a drying step the pieces (pellets) are first heated at a temperature in the range of 500.degree.-900.degree. C., e.g. 700.degree. C. and then at a temperature of about 1100.degree. C., e.g. 1100.degree.-1160.degree. C. This process yields a ceramic product which is environmetally safe.
A problem of the just mentioned process is that a substantial amount of energy should be supplied, in particular for the sintering step.
Surprisingly, it has been found that this problem can be solved by the combined treatment of waste materials of two types A and B. A being waste material having a relatively high energy content and B being a water containing waste material having a relatively low energy content.
SUMMARY OF THE INVENTION
According to the invention this treatment comprises the following steps: residue. mixture C, carbonaceous residue is used in such an amount that less than about 80% of the totally required baking energy is contained in mixture C.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of the process of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
In the process of the invention material A contains preferably more than 40 wt. %, in particular more than about 60 wt. % of organic material, said percentages being based on dry matter. Examples of material A are oil sludge and sludge of purification plants. Such a sludge may contain e.g. 40-90 wt. % of organic material, based on dry matter. A feature of purification sludge is the presence of organic material in the form of fibrous material. Fibrous material may comprise e.g. 20-60 wt. % of the sludge on a dry basis.
In the process according to the invention material B contains preferably less than about 30 wt. %, in particular less than 20 wt. % of organic material, said percentages being based on dry matter. Examples of material B are polluted soil and dredging mud such as harbour mud, but also mud from rivers and lakes. In general, material of this type contains about 2-30 wt. % of organic material on a dry basis. As opposed to purification sludge of type A, dredging mud and polluted soil comprise a "short" material and not a
REFERENCES:
patent: 4599954 (1986-07-01), Williams
patent: 4762527 (1988-08-01), Beshore et al.
patent: 4938155 (1990-07-01), Williams
patent: 5035189 (1991-07-01), Lunsford
Bouman Johannes
Quaak Marinus P.
Ecotechniek B.V.
Favors Edward G.
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